Software Design

Technical Components of an E-commerce System

2010-04-11T03:37:00.000-07:00

The Internet has had such a huge impact on the world (in business, media and society) that it is easy to overlook the technology that preceded it, that enabled it and that has evolved subsequently. In eCommerce terms, though, this does not mean that this technology is any less valid. Remember, we are trying to find the right tools for the right job.

Networks

Networks are electronic/data highways which link computers together for the purpose of sharing resources. They are characterised by:

· the type of data transmission technology they use;

· whether they carry voice, data, or voice and data;

· whether they are public or private (i.e. who can use them);

· the nature of connection - dial-up, dedicated or virtual connections;

· the types of physical links (such as optical fiber, coaxial cable, and copper wire).

The type of data transmission refers to the protocol they use, i.e. the set of rules for communicating that the end points in a connection use when they exchange signals. Both endpoints must understand and observe the protocol. The Internet uses TCP/IP protocols, which includes TCP (Transmission Control Protocol) and IP (Internet Protocol), HTTP, FTP and other protocols, each with a defined set of capabilities.

Local Area Networks (LANS)

LANs link a number of computers by relatively short lengths of cable, usually within the same room or building . Typically, a more powerful computer, called a server, will serve data and applications to a number of desktop PCs. Due to the short length of the cables, data transmission is very fast (MegaBits or even GigaBits per second). Company LANs are usually controlled by a member of the IT department called the network administrator.

It is important to recognise LANs as part of the communications infrastructure because they are often the basis of a company's IT systems. As such, any implementation of eCommerce will require integration of the LAN with external communications media. A LAN that uses Internet.Protocols is, essentially, an intranet, and can support applications run on the Internet if appropriate server software is installed.

The purpose of an intranet is to allow everyone to share information and facilitate group work processes. Like any other network, it holds file directories and allows resource sharing. Intranets are still very much in their infancy as regards the level of sophistication around the types of applications and information held on them. According to recent research completed by InformationWeek the most common applications on intranets are policy and procedure manuals, document sharing and corporate phone directories.

The intranet must have a firewall to prevent unauthorised access from outside the company. Firewalls are hardware/software combinations that allow people from outside an intranet to access data on the Internet, but keep intruders from getting onto the intranet. Depending on how secure a site needs to be and how much time, money and resources can be spent on a firewall, there are many kinds that can be built. Most of them, however, incorporate the following elements:

proxy servers;
routers;
bastion hosts.

Wide Area Networks (WANs)

WANs connect a number of computers, or LANs using long-distance connections. The connections may be along private cables, microwave or satellite links or may be leased from a network provider, such as an Internet Service Provider (ISP) or a telecoms operator. A WAN may contain a number of switching and relaying computers called 'nodes' or 'gateways'. A connection between two major nodes is called a 'backbone'. The Internet itself is a very large WAN. The extension of a simple LAN to the WAN is also the basis for the similar extension of the concept of the intranet to an extranet, which is a key component of business-to-business eCommerce. Essentially an extranet is a private network that uses the Internet protocols and the public telecommunication system to securely share part of a business's information or operations with suppliers, vendors, partners, customers, or other businesses. An extranet can be viewed as part of a company's intranet that is extended to users outside the company. Therefore, the same benefits that Internet technologies have brought to the Internet and to corporate intranets are now being made available to accelerate business between businesses.

An extranet requires security and privacy. These require firewall server management (in much the same way as intranets) and, increasingly, the use of Virtual Private Networks (VPN's - see below) that are able to tunnel securely through the public network.

The reasons why extranets are, potentially, so important to the area of business-to-business eCommerce, are that they allow organisations to:

· exchange large volumes of data using EDI;

· share product catalogues exclusively with wholesalers or distributors;

· collaborate with other companies on joint development efforts;

· jointly develop and use training programs with other companies;

· provide or access services provided by one company to a group of other companies, such as an online banking application managed by one company on behalf of affiliated banks;

· share news of common interest exclusively with trading partner companies.

Virtual Private Networks

Historically, organisations that needed to construct networks that would serve multiple sites, or maybe allow communication with their clients or suppliers, would achieve this by constructing a virtual private network,or VPN.

With the advent of the Internet, along with relatively cheap broadband access technologies, interest in constructing VPNs across the Internet has grown considerably because it has the potential to offer a VPN service at significantly lower cost than would be the case with networks constructed from dedicated leased lines. However, the very public nature of the Internet means that, although it is possible still to construct trusted VPNs in this environment, many users require a higher degree of assurance that their communications over the VPN will be secure. Hence, this has given rise to the use of technologies that allow secure VPNs to be constructed. The basic concept behind a secure VPN is that all communications taking place across the VPN are encrypted, thus preventing the data from being read in any meaningful form, even if a potential eavesdropper is able to examine the data packets being transmitted on the network. The devices communicating over the network, or the network users, or both, may well also need to be authenticated, to ensure that only trusted individuals or equipment can be attached to the network. Most current implementations of secure VPNs are based on a family of encryption technologies known as IPSec, which is used to construct a secure 'tunnel' across the Internet that can carry the client's data.

VPN technology is accessible to business users in a variety of forms. The telecommunications service providers have offered trusted VPN services for a number of years and, increasingly, are also offering secure VPN services. In both cases, the offering is a managed service, having the advantage of off-loading the maintenance and management of the network from the user. Perhaps the most interesting aspect of secure VPNs is that it is possible for these services to be provided and managed by the businesses that use them. As they rely on encryption technology that can be installed either as software in a PC or as add-ons to existing LANs, VPN services can potentially be used by all sizes of business user, from the SME up to the multi-national.

VPNs can significantly improve the security of communication within a distributed organisation. This can be important for:

· Internal communications within the organisation;

· Communications with client or trading partners, where confidentiality of commercially sensitive information may be a requirement;

· Providing secure networking for home workers.

The same secure VPN technology can also be applied as a means of overcoming the present shortcomings in wireless LAN security; if all information transmitted over the wireless LAN is properly encrypted using the IPSec mechanisms, it is no longer a concern that an eavesdropper might be able to 'see' the data packets being communicated, since it will be impossible to decrypt the data. Secure VPNs can, in many ways, be viewed as a means of making the other networking technologies safer to use in a commercial environment; hence, coupled with the other technologies mentioned in earlier sections, VPNs become an essential factor in delivering the benefits that can accrue from these technologies.

A major benefit with managed VPN services is that they significantly reduce the costs associated with constructing and managing a wide area data network. This can be significant for all sizes of business. Even the larger multinationals often cannot afford the expense of running a truly private WAN, whereas the established telecommunications suppliers can offer a managed service at a much more affordable cost.

Virtual private network technology is not only available today from companies specialising in VPNs, but also from operating system vendors (e.g. Microsoft) and traditional firewall vendors. There is limited interoperability between products from different vendors today, since standards are only now being finalised. Therefore, the user is likely to need software from the same vendor for both end points of the tunnels. The key standard that is emerging is IPsec (secure IP), whilst others include SOCKS and Layer 2 Tunneling Protocol (L2TP). The L2TP standard combines attributes of Microsoft's Point to Point Tunneling Protocol (PPTP) and Cisco's L2F (layer 2 forwarding.)

The development of E-Commerce in the context of business developments.

Communication

1. Options:

· Telephone: dial-up or leased line

· ISDN: basic rate or primary rate

· Value Added Networks

· X.400: ISO standard secure messaging

· Networks: local area networks, wide area networks or intranets

· Internet: messaging, file transfer, Telnet, World Wide Web, XML

2. Standards:

· Standards are the means by which data is sent in an agreed format by eCommerce trading partners.

· In Electronic Data Interchange (EDI), standards pertain specifically to the syntax used to prepare messages for exchange. They enable, for example, one accounts system to understand an electronic version of an invoice sent out by another accounts system because the relevant pieces of data (e.g. invoice number) are always located in the same part of the message.

· In the case of EDI, these standards are generally nationally and

· The means which data is sent in an agreed format by E-commerce trading partners.

E.g.:

· EDI: syntax used to prepare message for exchange

· Gif and JPG: graphic standards

· World Wide Web:HTML, PERL, Javascript, Java, Software

3. The e-commerce software function includes:

· Data extraction from relevant application or data entry

· Data encoding to agreed standard format

· Data transmission to recipients.

· Data receipt by recipients.

· Data decoding for internal applications.

· Data insertion into relevant applications

Business-to-Business E-commerce

Key areas in B2B e-commerce:

Electronic Data Interchange (EDI)
Enhanced messaging: e-mail, voice-mail, fax
Teleconferencing
Integrated Systems: intranets/extranets, database publishing, workflow

Supply Chain E-commerce

Key areas in B2B e-commerce:

Stock control
Just-in-time delivery
Transportation
Warehouse management
Automatic Identification: Barcodes, Transponders

Business-to-Consumer E-commerce

B2C e-commerce application includes:

Database application
Kiosks
Internet store fronts
Downloadable software and software support
Internet auctions
Advertising on the Internet
Interactive TV

Impact of E-commerce on the Business

The impact of E-commerce to business includes:

Instantaneous means of data exchange
Exchange information efficiently and accurately
Convenience in time and geographic.
Reducing manual and paper-based operations
Re-thinking and simplifying the information flow
Using the information flow in new and dynamic ways.

Business Process Re-design

BPR focuses on radically changing the way internal processes are conducted in order to increase profitability and competitiveness.
E-commerce provides an opportunity to radically re-engineer business processes, even those that may have already been subject to such an activity.
Workflow is used to within the BPR project to help rationalise internal business procedures.
Flexible Working is an approach to organising the way people work together, from employees to top management and the way they interact with trading partners. It consist of:

Teleworking : Working a day or more from home and the rest at the office
Mobile working : Profession that requires the person to move from place to place and yet maintain contact with an office.
Virtual Teams : Teleworking extended to a group of people working on one task or project.

E Commerce

2010-04-11T03:28:00.000-07:00

1.0 Defining E-Commerce

· E-commerce covers any form of business transaction or information exchange that is executed using any form of information and communications technology. This embraces business-to-business; business-to-consumer; and government-to-nation; as well as exchange of tools like the Internet and the World Wide Web, intranets, extranets, electronic mail and Electronic Data Interchange. (UK’s e-centre)

· Brief history of E-Commerce;

§ look at what drives E-Commerce;

§ look at the components of an E-Commerce system;

§ list the range of E-Commerce techniques; identifying them within different business contexts;

§ start to look at the impact of E-Commerce on the organisation.

· The application of advanced information technology to increase the effectiveness of the business relationships between trading partners. (Automotive Industry Action Group in North America)

The enablement of a business vision supported by advanced information technology improves efficiency and effectiveness within the trading process. (E-Commerce Innovation Centre at Cardiff University)

The development of E-Commerce in the context of technological developments of the IT world today;

As the current environment provides affordable, more powerful and user-friendly systems, this has promoted the need of a system as a tool provider for business.

The development of EDI (Electronic Data Interchange) brought about data to transfer from one system to another. EDI was widely used in the 1980s and early 1990s. The latter developments were of the X.400 and the Internet.

2.0 Electronic commerce (E-commerce)

· The process of buying, selling, transferring, or exchanging products, services and/or information via computer networks, including the Internet

· The origins of e-commerce first started with innovations such as electronic fund transfer (EFT) in which funds could be routed electronically form one organisation to another

· Then came Electronic Data Interchange (EDI), a technology used to electronically transfer routine documents, which expanded electronic transfers from financial transactions to other types of transaction processing such as ordering

· EDI required having expensive dedicated and private lines between the trading parties

· Internet and WWW overcome the shortcomings of EDI

Electronic Business

· A broader definition of EC, includes not just the buying and selling of goods and services, but also servicing customers, collaborating with business partners, and conduction electronic transactions within an organisation.

· E-Business is the use of the Internet and other information technologies to support commerce and improve business performance.

· Some view e-business as comprising those activities that do not involve buying and selling over Internet, such as collaboration and intrabusiness activities.

4.0 Types of EC organisations

· Brick and Mortar Organization - Old-economy organizations that perform most of their business off-line, selling physical products by means of physical agents. Purely physical organization.

· Virtual (Pure-Play) Organization – Organization that conduct their business activities solely.

· Click and mortar organization – organization that conduct some e-commerce activities, but do their primary business in the physical world.

5.0 World Wide Web

· Created in the early 1990s Tim Berners-Lee

· Software that allows users to exchange information as it was designed to help scientists share online information using a single, unified interface.

· Mid-1993, Marc Andressen, an undergraduate of University of Illinois, wrote a program called Mosaic, which made using the web as easy as pointing and clicking at pictures and underlined words

· Mosaic was the first graphical browser that was launched with 150 websites holding a few thousand web-pages.

· 1995 there were about 10,000 sites, a number that had grown to 4 - 5 m by mid-1999.

· Commercial use of the Internet has skyrocketed, with companies using the Internet to communicate with each other, with their customers, with their partners and with their suppliers.

6.0 Electronic markets

Classification of EC by the nature of the transactions / interactions:

1. Business-to-business (B2B) – all of the participants are businesses or other organizations e.g suppliers

2. Business-to-Consumer (B2C) / e-tailing – includes retail transactions of products and services from businesses to individual shoppers

3. Business-to-business-to-consumer (B2B2C) – a business provides some product or service to a client business that maintain its own customers

4. Consumer-to-business (C2B) – individuals who use the Internet to sell products or services to organisations, or individuals seek sellers to bid on products or services they need

5. Consumer-to-consumer (C2B) - consumers ell directly to other consumers

6. Peer-to-peer applications – technology that enables networked peer computers to share data and processing with each other directly, can be used in C2C, B2B, and B2C ecommerce

7. Mobile-commerce (m-commerce) – e-commerce transactions and activities conducted in a wireless environment

8. Intra-business EC – includes all internal organisational activities that involve the exchange of goods, services, or information among various units and individuals in an organisation

9. Location-based commerce (l-commerce) – m-commerce transactions targeted to individuals in specific locations, at specific times

10. Business-to-employees (B2E) – organisations deliver services, information or products to its individual employees

11. Collaborative commerce (c-commerce) – individuals or groups communicate or collaborate online

1. E-learning – online delivery of information for the purposes of training or education

2. Exchange-to-exchange (E2E) – electronic exchanges formally connect to one another for the purpose of exchanging information

3. E-government – a government entity buys or provides goods services, or information to businesses (G2B)or individual citizens (G2C)

7.0 Benefits

· Global reach – expands the marketplace to national and international markets. With minimal capital outlay, a company can easily and quickly locate the best supplier, more customers, and the most suitable business partners worldwide.

· Cost reduction – decrease the cost of creating, processing, distributing, storing, and retrieving paper-based information.

· Supply chain Improvements – supply chain inefficiencies, such as excessive inventories and delivery delays can be minimized with EC.

· Extended hours – 24/7/365 the business always open on the Web, with no overtime or other extra costs.

8.0 Limitations

· costs of a technological solution

· some protocols are not standardized around the world

· reliability for certain processes

· insufficient telecommunications bandwidth

· Software tools are not fixed but constantly evolving (ie. Netscape 3,4,4.7,4.75 etc.)

· some vendors require certain software to show features on their pages, which is not common in the standard browser used by the majority

· Difficulty in integrating e-Commerce infrastructure with current organizational IT systems

7.0 E-Marketplace

An online marketplace where buyers and sellers meet to exchange goods, services, money or information.

E-markets may be supplemented by interorganizational or intraorganizational information systems

· integrating digital and non-digital sales and production information

· access limitations of dial-up, cable, ISDN, wireless

Naming

2010-03-03T21:38:00.000-08:00

Every programming language has its own set of rules and conventions for the kinds of names that you're allowed to use, and the Java programming language is no different. The rules and conventions for naming your variables can be summarized as follows:

Variable names are case-sensitive. A variable's name can be any legal identifier — an unlimited-length sequence of Unicode letters and digits, beginning with a letter, the dollar sign "$", or the underscore character "_". The convention, however, is to always begin your variable names with a letter, not "$" or "_". Additionally, the dollar sign character, by convention, is never used at all. You may find some situations where auto-generated names will contain the dollar sign, but your variable names should always avoid using it. A similar convention exists for the underscore character; while it's technically legal to begin your variable's name with "_", this practice is discouraged. White space is not permitted.
Subsequent characters may be letters, digits, dollar signs, or underscore characters. Conventions (and common sense) apply to this rule as well. When choosing a name for your variables, use full words instead of cryptic abbreviations. Doing so will make your code easier to read and understand. In many cases it will also make your code self-documenting; fields named cadence, speed, and gear, for example, are much more intuitive than abbreviated versions, such as s, c, and g. Also keep in mind that the name you choose must not be a keyword or reserved word.
If the name you choose consists of only one word, spell that word in all lowercase letters. If it consists of more than one word, capitalize the first letter of each subsequent word. The names gearRatio and currentGear are prime examples of this convention. If your variable stores a constant value, such as static final int NUM_GEARS = 6, the convention changes slightly, capitalizing every letter and separating subsequent words with the underscore character. By convention, the underscore character is never used elsewhere.

· Identifier- a string of characters used to identify (or name) some element of a programme. The kind of elements that can be named depends on the programming language; it may be a variable, a data structure, a procedure, a statement, a higher-level unit, or the programme itself.

· Name-a notation for indicating an entity in a programme or system.

· Reserved word-a word that has a specific role in the context in which it occurs, and therefore cannot be used for other purposes.

· Keyword-a symbol in a programming language that has a special meaning for the compiler or interpreter.

· Compiler-a programme that translates high-level language into absolute code, or sometimes into assembly language

· Interpreter-a language processor that analyses a line of code and then carries out the specified action, rather than producing a machine-code translation to be executed later.

Variable types

2010-03-03T21:29:00.000-08:00

4 byte: The byte data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters. They can also be used in place of int where their limits help to clarify your code; the fact that a variable's range is limited can serve as a form of documentation.

4 short: The short data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive). As with byte, the same guidelines apply: you can use a short to save memory in large arrays, in situations where the memory savings actually matters.

4 int: The int data type is a 32-bit signed two's complement integer. It has a minimum value of -2,147,483,648 and a maximum value of 2,147,483,647 (inclusive). For integral values, this data type is generally the default choice unless there is a reason (like the above) to choose something else. This data type will most likely be large enough for the numbers your program will use, but if you need a wider range of values, use long instead.

4 long: The long data type is a 64-bit signed two's complement integer. It has a minimum value of -9,223,372,036,854,775,808 and a maximum value of 9,223,372,036,854,775,807 (inclusive). Use this data type when you need a range of values wider than those provided by int.

4 float: The float data type is a single-precision 32-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion, but is specified in section 4.2.3 of the Java Language Specification. As with the recommendations for byte and short, use a float (instead of double) if you need to save memory in large arrays of floating point numbers. This data type should never be used for precise values, such as currency. For that, you will need to use the java.math.BigDecimal class instead. Numbers and Strings covers BigDecimal and other useful classes provided by the Java platform.

4 double: The double data type is a double-precision 64-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion, but is specified in section 4.2.3 of the Java Language Specification. For decimal values, this data type is generally the default choice. As mentioned above, this data type should never be used for precise values, such as currency.

4 boolean: The boolean data type has only two possible values: true and false. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defined.

4 char: The char data type is a single 16-bit Unicode character. It has a minimum value of '\u0000' (or 0) and a maximum value of '\uffff' (or 65,535 inclusive).

Analysis Concepts & Principles

2009-03-19T04:50:00.000-07:00

1.0 Requirements Analysis

Requirements Analysis is the process of understanding the customer needs and expectations from a proposed system or application and is a well-defined stage in the Software Development Life Cycle model.
Requirements are a description of how a system should behave or a description of system properties or attributes.
It can alternatively be a statement of ‘what’ an application is expected to do, not ‘how’.
Software engineering task that bridges the gap between system level requirements engineering and software design.
Software requirements analysis may be divided into give areas of effort

Problem recognition
Evaluation and synthesis
Modeling
Specification
Review

Requirements analysis encompasses those tasks that go into determining the requirements of a new or altered system, taking account of the possibly conflicting requirements of the various stakeholders, such as users.
Requirements analysis is critical to the success of a project.
It is sometimes referred to loosely by names such as requirements gathering, requirements capture, or requirements specification.
The term “requirements analysis” can also be applied specifically to the analysis proper.
Requirements must be measurable, testable, related to identified business needs or opportunities, and defined to a level of detail sufficient for system design.
Five common errors in requirements analysis:

Customers do not really know what they want
Requirements change during the course of the project
Customers have unreasonable timelines
Communication gaps exist between customers, engineers and project managers
The development team does not understand the politics of the customer’s organization

2.0 Requirements Elicitation for Software

Before requirements can be analyzed, modeled, or specified they must be gathered through an elicitation process.

Initiating the Process

The most commonly used requirements elicitation technique is to conduct a meeting or interview

Facilitated Application Techniques

This approach encourages the creation of a joint team of customers and developers who work together to identify the problem, propose elements of solution, negotiate different approaches and specify a preliminary set of solution requirements

Quality Function Deployment

A technique that translates the needs of the customer into technical requirements for software
QFD identifies three types of requirements

Normal requirements – the objectives and goals that are stated for a product or system during meeting with the customer
Expected requirements – these requirements are implicit to the product or system and may be so fundamental that the customer does not explicitly state them
Exciting requirements – these features go beyond the customer’s expectations and prove to be very satisfying when present

Interviews

A “traditional” means of eliciting requirements.
It is important to understand the advantages and limitations of interviews and how they should be conducted.

Use-Cases

As requirements are gathered as part of informal meetings, FAST, or QFD, the software engineer can create a set of scenarios that identify a thread of usage for the system to be constructed.

Prototype

A valuable tool for clarifying unclear requirements.
They can act in a similar way to scenarios by providing users with a context within which they can better understand what information they need to provide.
There is a wide range of prototyping techniques, from paper mock-ups of screen designs to beta-test versions of software products, and a strong overlap of their use for requirements elicitation and the use of prototypes for requirements validation.

3.0 Analysis Principles

All analysis methods are related by a set of operational principles

The information domain of a problem must be represented and understood
The functions that the software is to perform must be defined
The behavior of the software must be represented
The models that depict information, function, and behavior must be partitioned in a manner that uncovers detail in a layered fashion
The analysis process should move from essential information toward implementation detail

In addition to these operational analysis principles, a set of guiding principles for requirements engineering are suggested as

Understand the problem before you begin to create the analysis model
Develop prototypes that enable a user to understand how human/machine interaction will occurs
Record the origin of an the reason for every requirement
Use multiple view of requirements
Rank requirements
Work to eliminate ambiguity

4.0 Specification

Specification principles

Separate functionality from implementation
Develop a model of the desired behavior of a system that encompasses data and functional response of a system to various stimuli from the environment
Establish the context in which software operates by specifying the manner in which other systems components interact with software
Define the environment in which the system operates and indicate how “a highly intertwined collection of agents react to stimuli in the environment (changes to objects) produced by those agents”
Create a cognitive model rather than a design or implementation model. The cognitive model describes a system as perceived by its user community
Recognize that “the specifications must be tolerant of incompleteness and augmentable.” A specification is always a model-an abstraction-of some real situation that is normally quite complex. Hence, it will be incomplete and will exist at many level of detail
Establish the content and structure of a specification in a way that will enable it to be amenable to change

Representation

Representation format and content should be relevant to the problem
Information contained within the specification should be nested
Diagrams and other notational forms should be restricted in number and consistent in use
Representations should be revisable

The software requirements specification

Is produced at the culmination of analysis task.
The function and performance allocated to software as part of system engineering are refined by establishing a complete information description, a detailed functional description, a representation of system behavior, an indication of performance requirements and design constraints, appropriate validation criteria, and other information pertinent to requirements.
Format of software requirements specification:

Introduction
Information description
Functional description
Behavioral description
Validation criteria
Bibliography and appendix

5.0 Specification Review

A review of the Software Requirements Specification is conducted by both the software developer and the customer.
Because the specification forms the foundation of the development phase, extreme care should be taken into conducting the review.
Once the review is complete, the Software Requirements Specification is “signed-off” by both the customer and developer.

The specification becomes a “contract” for software development

CASE Tool

2009-03-19T04:46:00.000-07:00

1.0 Introduction

· CASE tool is an acronym for ‘Computer Aided Software engineering’ – the automation of step-by-step methodologies for software and systems development to reduce the amount of repetitive work the developer needs to do.

· Computer-aided Software Engineering (CASE), in the field software engineering is the scientific application of a set of tools and methods to software which results in high-quality, defect-free, and maintainable software products.

· It also refers to methods for the development of information systems together with automated tools that can be used in the software development process.

· Generally, a CASE tool environment may be expected to provide the following:

Automated graphics facilities for producing charts and diagrams in support of modeling activities
Screen and report generators to assist in designing the dialogue/presentation of the proposed information systems
Data dictionaries providing a central repository for all definitions used by the development team
Reporting facilities ranging from project management statistics through to design inconsistencies
Analysis and cross-referencing tools to ensure integration of model views
Code generators and documentation generators utilising the deliverables of the modeling activities to develop working systems

2.0 How CASE tools try to increase quality and productivity

1. Enforcing a standard development methodology and design principle

2. Providing a central repository for all design components and making them available to all the design team

3. By improving communications between the designers and end-users using graphical representations of the system design

4. Automating tedious and error-prone analysis and design activities thus proving consistency between views

5. By automating code generation (to a certain degree), testing and version/change control activities

3.0 Classification of CASE tools

· CASE tools are often classified as upper CASE tools, lower CASE tools or Integrated CASE (I-CASE) tools. These terms refers refers to the functions supported by the tool

· An upper CASE tool supports front-end activities that focus upon capturing analysis and design information in the early stages of systems development. These CASE tools support, specifically, the modelling activities vital to the analysios and design stages of a development project

· Lower CASE tools support the back-end activities of a development project. By this we mean those activities concerning aspects of physical design, programming and implementation.

· I-CASE is used to desribe a tool that combines elements of both Upper CASE and Lower CASE tools into a single integrated development support environment

Upper CASE tool

Modeling Features, Analysis tools, Cross referencing tools, Central Repository, Documenetation generators

Logical

I-CASE tool

Modeling Features, Analysis tools, Cross referencing tools, Code generators, Testing, Screen/Report generators, Central Repository, Documentation generators

Lower CASE tool

Code generators, Testing Screen/Report generators, Central Repository, Documentation generators

Physical

· CASE tools can be classified based on functionality. Some of these is listed below:

Ø Management tools: PERT tools, estimation tools

Ø Editing tools: Test editors, diagram editors, word processors

Ø Configuration management tools: Version management system, change management systems

Ø Prototyping tools: Very high-level languages, user interface generators

Ø Method supports tools: Design editors, data dictionaries, code generators

Ø Language processing tools: Compiler, Interpreters

Ø Program analysis tools: Cross-reference generators, static analyzers, dynamic analyzers

Ø Testing tools: Test data generators, file comparators

Ø Debugging tools

Ø Documentation tools

Ø Re-engineering tools: Cross-reference system, program restructuring systems

· Existing CASE Environments can be classified along 4 different dimensions :

Life-Cycle Support
Integration Dimension
Construction Dimension
Knowledge Based CASE dimension

4.0 CASE Workbenches

· CASE workbenches are collections of integrated tools, which support a specific software life cycle stage.

· CASE tools to support analysis & design, programming and testing are widely used in industry.

· The integration mechanism can be either public or proprietary

Ø Public: the users can add their own tools to a workbench. Such a workbench is an open system

Ø Proprietary: the addition of third-party tools is usually impossible. Such a workbench is closed system

· The advantages of open workbenches are as follows:

New specialist tools can be added
The outputs from tools can be used by other systems, for example, a configuration management system
More complex tools can be gradually introduced
Different tool vendors can be used

· Programming Workbenches: Is a set of integrated tools to support the process of program development.

· A typical programming workbench includes the following tools:

· Language compiler

· Structured editor: to create and edit source programs

· Linker: to link object code components

· Loader: to load an executable program into the computer memory

· Cross-referencer: to produce a cross-reference listings of source programs

· Static analyzer: to analyze source programs in order to find anomalies

· Dynamic analyzer: to analyze how many times each statement of a source program has been executed when the program was run

· Interactive degugger: to trace and control the execution of user program

· Analysis & Design Workbenches: Typical components of an analysis & design workbench are:

· Diagramming editors: Are used to create DFDs, ERDS charts etc. The editor is not just a drawing tool but understands the meaning of different symbols/objects. It captures information about these objects and saves this information in a central repository.

· Checking facilities: Are used to ensure that models created by analysts/designers are internally consistent and complete and all models are consistent with one another (externally consistent)

· Query language facilities: Is used to browse the repository and examine completed designs

· Data dictionary facilities: Are used to maintain information about the objects used in various diagrams

· Report generation facilities: Are used to automatically generate system documentation

· Form generation tools: Are used to specify screen and document formats

· Skeleton code generators: Are used to generate code or code segments automatically from the design stored in the central repository

· Import/Export facilities: Allow the interchange of information with other development tools

· Testing Workbenches: Testing workbenches are open collections of testing tools. A typical testing workbench consists of:

· Test manager: to record testing

· Test data generator: to generate test cases

· Oracle: to generate predictions of expected results

· File comparators: to compare results of program test

· Report generator: to automatically generate system documentation

· Dynamic analyzer: to analyze how many times each statement of a source program has been executed when the program was run. It is useful to produce an execution profile of the tested program to achieve the proper coverage for white box testing

· Simulator: to simulate an environment (Eg; hardware, users) for tested programs. Simulators are very useful when testing real-time systems

5.0 Benefits of CASE tools

1.	Project Management and control is improved: CASE tools can aid the project management and control aspects of a development environment. Some CASE tools allow for integration with industry-standard project management methods (such as PRINCE). Others incorporate project management tools such as PERT charts and critical path analysis. By its very nature, a CASE tool provides the vehicle for managing more effectively the development activities of a project.
2.	System Quality is improved: CASE tools promote standards within a development environment. The use of graphical tools to specify the requirements of a system can also help remove the ambiguities that often lead to poorly defined systems. Therefore, if used correctly, a CASE tool can help improve the quality of the specification, the subsequent design and the eventual working system.
3.	Consistency checking is automated: Large amounts of information about a business area and its requirement are gathered during the analysis phase of an information systems development project. Using a manual system to record and cross reference this information is both time-consuming and inefficient. One of the advantages of using CASE tool is that all data definitions and other relevant information can be stored in a central repository that can then be used to cross check the consistency of the different views being modelled.
4.	Productivity is increased: One of the most obvious benefits of a CASE tool is that it may increase the productivity of the analysis team. If used properly, the CASE tool will provide a support environment enabling analysts to share information and resources, manage the project effectively and produce supporting documentation quickly.
5.	The maintenance effort is better supported: It has been argued that CASE tools help reduce the maintenance effort required to support the system once it is operational. CASE tools can be used to provide comprehensive and up-to-date documentation – this is obviously a critical requirement for any maintenance effort. CASE tools should result in better systems being developed in the first place.

6.0 Problems associated with CASE tools

1.	Need for organization - wide commitment: To be used effectively, CASE tools require the commitment of the organisation. Every member of the development team must adhere to the standards, rules and procedures laid down by the CASE tool environment.
2.	Unrealistic expectations: CSE tools cannot replace experienced business/systems analysts and designers. They cannot automatically design a system nor can they ensure that the business requirements are met. Analysts and designers still need to understand the business environment and identify the system requirements. CASE tools can only support the analytical skills of the developers, not replace them.
3.	Long learning curve: CASE is technical software. It will take time for the development team to get use to flow and use it effectively for development work.
4.	Costs of CASE tools: CASE tools are complicated software packages and are, therefore, expensive to buy. In addition to the initial costs, there are many ‘soft’ costs that have to be considered. These ‘soft costs’ include integration of the new tool, customising the new tool, initial and on-going training of staff, hardware costs and consultancy provided by the CASE tool vendor.

Common CASE risks and associated controls include:

Inadequate Standardization : Linking CASE tools from different vendors (design tool from Company X, programming tool from Company Y) may be difficult if the products do not use standardized code structures and data classifications. File formats can be converted, but usually not economically. Controls include using tools from the same vendor, or using tools based on standard protocols and insisting on demonstrated compatibility. Additionally, if organizations obtain tools for only a portion of the development process, they should consider acquiring them from a vendor that has a full line of products to ensure future compatibility if they add more tools.
Unrealistic Expectations : Organizations often implement CASE technologies to reduce development costs. Implementing CASE strategies usually involves high start-up costs. Generally, management must be willing to accept a long-term payback period. Controls include requiring senior managers to define their purpose and strategies for implementing CASE technologies.
Quick Implementation : Implementing CASE technologies can involve a significant change from traditional development environments. Typically, organizations should not use CASE tools the first time on critical projects or projects with short deadlines because of the lengthy training process. Additionally, organizations should consider using the tools on smaller, less complex projects and gradually implementing the tools to allow more training time.
Weak Repository Controls : Failure to adequately control access to CASE repositories may result in security breaches or damage to the work documents, system designs, or code modules stored in the repository. Controls include protecting the repositories with appropriate access, version, and backup controls.

7.0 Example of CASE tools

· SELECT Enterprise : SELECT Enterprise is described as ‘ a dedicated modeling toolset for building scaleable client/server applications’ . it provides integrated business process modeling, use case and object modeling based upon the UML development environment.

· ORACLE Designer 2000 : ORACLE designer is one of the products offered by the ORACLE corporation. It is described as ‘a model-based development toolset utilising a multi-user, repository-based environment’ . The definitions of all model elements (Eg; entities, table definitions) are centrally stored in a repository, making them available to all members of the development team when and where they require them. Designer 2000 supports a number of complementary analysis techniques : process models, entity relationship diagrams, data flow diagrams etc.

· Rational Rose : Rational Rose is a CASE toolset designed to support the UML development environment. The main benefits of rational Rose are described as multi-language support (C++, JAVA, VB, ADA), integrates with other industry standard environments and has a platform-independent development environment.

Variable, Control Structure and Calculation.

2009-03-11T08:32:00.000-07:00

Introduction

4 Every programming language, like languages such as English, has rules which must be followed. The rules that defines the legal sequences of symbolic elements in a language is refers as SYNTAX. The building blocks of programming language are keywords (While_Loop, Repeat_Untill) which have a special meaning in the programming language.

4 Pseudocode is one of the tools that can be used to write a preliminary plan which can be developed into a computer program.

o It is not a standard language, its purpose is to describe the algorithm in a form that can easily be understood and then translated into the actual programming code required.

4 The syntax of the language to be used and the fine detail of the program are ignored until writing the source code.

Variable Types and Names

4 Variable is a unit of storage that can be modified during programme execution, usually by assignment or read operations.

4 A variable is generally denoted by an identifier or by name.

· The name denotes a modifiable unit of storage.

· Attributes of the variable:

The address in memory where the data is stored
The actual data stored which can change during the execution of the program
The name of the variable or identifier

Software Process Models (Cont)

2009-03-10T19:09:00.000-07:00

3.3 Prototyping Model

· A prototype is a working model that is functionally equivalent to a component of the product.

· In many instances the client only has a general view of what is expected from the software product.

· In such a scenario where there is an absence of detailed information regarding the input to the system, the processing needs and the output requirements, the prototyping model may be employed.

· This model reflects an attempt to increase the flexibility of the development process by allowing the client to interact and experiment with a working representation of the product.

· The developmental process only continues once the client is satisfied with the functioning of the prototype.

· At that stage the developer determines the specifications of the client’s real needs.

· A prototype is an initial version of a software system which is used to demonstrate concepts, try out design options, and generally, to find out more about the problem and its possible solutions.

· It is based on the idea of developing an initial implementation, exposing this to user comment and refining this through many versions until an adequate system has been developed.

· There are two type of prototyping approaches:

o Evolutionary Prototyping

o ‘Throw-Away’ Prototyping

· This approach extends the requirements analysis process with the intention of reducing overall life-cycle costs.

· The principal function of the prototype is to clarify requirements and provide additional information for managers to assess process risks.

· After evaluation, the prototype is thrown-away.

· It is not used as a basis for further system development.

3.4 Incremental Model

· The waterfall model requires users to commit to a set of requirements and designers to commit to particular design strategies.

· Changes to the requirements during development require rework of the requirements, design and implementation.

· However, the advantages of the waterfall model are that it is a simple management model and its separation of design and implementation should lead to robust systems which are amenable to change.

· The prototyping approach to development allows requirements and design decisions to be delayed but also leads to software which may be poorly structured, difficult to understand and maintain.

· Incremental development is an in-between approach which combines the advantages of both of these models.

· Incremental approach to development is a mean of reducing rework in the development process and giving users some opportunities to delay decisions on their detailed requirements until they had some experience with the system.

· The first increment is usually the core product which addresses the basic requirements of the system.

· This maybe either be used by the client or subjected to detailed review to develop a plan for the next increment.

· This plan addresses the modification of the core product to better meet the needs of the customer, and the delivery of additionally functionality.

· More specifically, at each stage:

o The client assigns a value to each build not yet implemented

o The developer estimates cost of developing each build

o The resulting value-to-cost ratio is the criterion used for selecting which build is delivered next

· Essentially the build with the highest value-to-cost ratio is the one that provides the client with the most functionality (value) for the least cost.

· Using this method the client has a usable product at all of the development stages.

· When the services in an increment have a well-defined specification, a waterfall model may be used. If the specification is unclear, prototyping can be used.

· Advantages:

1.	Customers do not have to wait until the entire system is delivered until they gain value from it. The first increment satisfies their most critical requirements so the software can be immediately used.
2.	Customers can use the early increments as a form of prototype and gain experience which informs the requirements for later system increments
3.	There is a lower risk of overall project failure. Although problems may be encountered in some increments, it is likely that some will be successfully delivered to the customer
4.	As the highest priority services are delivered first and later increments are integrated with them, it is inevitable that the most important system services receive the most testing. This means that customers are less likely to encounter software failures in the most important parts of the system

· Problems

Increments should be relatively small and each increment should deliver some system functionality. It may be therefore be difficult to map the customer’s requirements onto increments of the right size.

Most system require a set of basic facilities which are used by different parts of the system. As requirements are not defined in detail until an increment is to be implemented, it is difficult to identify common facilities that all increments require

3.5 Spiral Model

· Originally proposed by Boehm (1988)

· The software process is represented as a spiral.

· Each loop in the spiral represents a phase of the software process. E.g. the innermost loop might be concerned with system feasibility, the next loop with system requirements definition, the next loop with system design and so on.

· The evolutionary process begins at the centre position and moves in a clockwise direction.

· Each traversal of the spiral typically results in a deliverable.

· An important distinction between the spiral model and other software models is the explicit consideration of risk.

· There are no fixed phases such as specification or design phases in the model and it encompasses other process models.

Each loop in the spiral is split into 4 sectors

History of Programming

2009-03-10T05:58:00.000-07:00

What is a Programming Language?

· Programming language is a set of words, symbols, and codes that enables a programmer to communicate a solution algorithm to a computer.

· It is needed to allow human begins and computers to talk to each other.

· A programmer can use a variety of programming languages to code a program.

· A program development tool consists of user-friendly software products designed to assist both programmers and non-technical users with the creation of information system solutions.

Generation of Programming Language

· The first generation of language was the machine language. The machine language instruction uses a series of binary digits or a combination of numbers and letters that represents binary digits. Instructions and addresses were numerical.

· The second generation of language was the symbolic instructions or mnemonics and addresses. To convert the assembly language source program into machine language, you use an assembler. Example, IBM, BAL and VAX macro.

· The third generation language was the programmer concentration of structured programming and database management. It is a procedural language that requires the program instruction to tell the computer what to accomplish and how to do it. Example, FORTRAN, ADA, COBOL, Pascal, C and BASIC.

· The fourth generation (4GL) was the non-procedural type language. The programmer only specifies what the program should accomplish without explaining how. Example. SQL, Postscript, and relational database orientation.

· The fifth generation (5GL) was concerned on Artificial Intelligence and Fuzzy Logic.

Introduction to Java

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Objective

§              Understand and learn the basic structure of Java like variable declaration, data type and operator.

Activities

§              An overview of how the Java run-time works, byte code, need for a JVM.

§              Understand a simple Java applet and application and show students how to compile and execute.

§              Cover the basics of the character set, identifiers, primitive types and literals.

§              An overview of how operators and expressions are written.

Objective

§              Understand Java IO package and learn how to use it to get input from keyboard.

Activities

§              How to declare variables and default initial values.

§              Understand about type compatibility and conversion (Integer.parseInt(), Double.parseDouble()).

§              How to declare InputStreamReader and BufferedReader class and use it to read user input.

Visual Basic Simple Animation

2009-03-09T04:32:00.001-07:00

How to make a program with visual basic 2008

2009-03-09T04:26:00.000-07:00

Software Process Models

2009-03-07T05:27:00.000-08:00

Introduction

·A structured set of activities required to develop a software system

1.Specification

2.Design and Implementation

3.Validation

4.Evolution

·A software process model is an abstract representation of a process.

·It presents a description of a process from some particular perspective.

·Software process is a set of activities and associated results which lead to the production of a software product

·These may involve the development of software from scratch although it is increasingly the case that new software is developed by extending and modifying existing systems

·Software processes are complex and, like all intellectual processes are reliable on human judgments

·Because of the need for judgments and creativity, attempts to automate software processes have met with limited success

·CASE tools can support some process activities but there is no possibility, at lest for the next few years, of more extensive automation where software takes over creative design from the engineers involve in software process

·One reason why there is limited scope for process automation is the immense diversity of software processes

·There is no ideal process and different organizations have developed completely different approaches to software development

·The software process model maybe define

d as a simplified description of a software process, presented from a particular perspective.

·In essence, each stage of the software process is identified and a model is then employed to represent the inherent activities associated within that stage.

·Consequently, a collection of ‘local’ models may be utilised in generating the global picture representative of the software process.

·Examples of models include the workflow model, the data-flow model, and the role model.

1.The workflow model shows the sequence of activities in the process along with their inputs, outputs and dependencies. The activities in the model represent human actions.

2.The dataflow model represents the process as a set of activities each of which carries out some data transformation. It shows how the input to the process such as specification is transformed to an output such as design. The activities here maybe lower than in a workflow model. They may represent transformations carries out by people or computers.

3.The role model represents the roles of people involved in the software process and the activities for which they are responsible.

2.0 Approaches to Software Development

2.1 Traditional approaches

·In this model, ‘traditional’ tends to mean ‘unstructured’ and somewhat non-specific.

·This approach is characterized by the lack of user involvement, the use of text-based, as opposed to diagrammatic, documentation and an emphasis on how things are going to be achieved rather than what is going to be achieved.

·Although there is a stage-by-stage approach, it is difficult to see how the stages link together.

·There is no business case or defined acceptance criteria for the system, which makes it rather difficult to gauge success or failure

·On the other hand, this method of working suited many analysts and users. It allows the analyst to use ‘intuitive’ methods of working and made limited demands on the user’s time. The documentation was relatively easy to understand. Many traditional approaches follow a ‘Waterfall’ style of system development.

2.2 Structured approaches

·Structured methods have largely taken over from the traditional approach in the development of IS projects. Most of these methods offer a set of techniques and tools to carry out the system development work within a defined framework. Structured approaches are largely characterized by: User involvement, Separation of logical & physical work, Emphasis on data, Diagrammatic documentation and Defined structure.

·In general, structured methods are considered to offer improvements over traditional methods but there are drawbacks and criticisms. The users and analysts/ developers need to be trained to understand the documentation. This is important as there is no value whatsoever in producing documentation to be reviewed and signed off if it is not fully understood. The users also need to accept that the amount of time required from them will be much increased. Structured system Analysis & Design Method (SSADM) is an example of a structured method.

·Structured methods use tools such as Data Flow diagram (DFD) to model process, Entity Relationship Diagram (ERD) to model data, Entity Life History (ELH) to model behavior and decision tables / trees to model logic.

2.3 Evolutionary approaches

·This approach has prototyping as a central method that is used to develop systems. The approach interleaves the activities of specification, development and validation. An initial system is rapidly developed from very abstract specifications. This is then refined with customer input to produce a system which satisfies the customer’s needs. The system may then be delivered. Alternatively, it may be re-implemented using a more structured approach to produce a more robust and maintainable system. Example of such approach is the Incremental development and Spiral model.

2.4 Formal transformation

·This approach is based on producing a formal mathematical system specification and transforming this specification, using mathematical methods, to a program. These transformations are ‘correctness-preserving’. This means that it is assured that the developed program meets its specifications.

3.0 Models

3.1 The ‘Waterfall’ Model

·Also known as the software life-cycle model (classic life-cycle, liner sequential model).

·Cascade from one phase to another. Systematic and sequential approach to software development.

·Presents a highly structured method of software development that starts at the system level and progresses through analysis, design, coding, testing and maintenance.

.The stages of the model are as follows:

· However, the ‘waterfall-model’ is a suitable model for large projects. It becomes a very useful model if the requirements are clearly understood.

gather requirements
developer & customer define overall objectives, identify areas needing more investigation – risky requirements
quick design focusing on what will be visible to user – input & output formats
use existing program fragments, program generators to throw together working version
prototype evaluated and requirements refined
process iterated until customer & developer satisfied

then throw away prototype and rebuild system to high quality
alternatively can have evolutionary prototyping – start with well understood requirements

The V-model of a system development process incorporates test plans into it activities.
Drawbacks:

Customer may want to hang onto first version, may want a few fixes rather than rebuild.
First version will have compromises.
Developer may make implementation compromises to get prototype working quickly.

Later on developer may become comfortable with compromises and forget why they are inappropriate

Introduction to Software Principles (Cont)

2009-03-07T05:15:00.000-08:00

1.0 Software Characteristics

Software is a general term for the various kinds of programs used to operate computers and related devices.

Software can be thought of as the variable part of a computer and hardware the invariable part.

Software is a logical rather than a physically system element.

Therefore, software has characteristics that differ considerably from those of hardware:

1. Software is tangible

2. Software is developed or engineered, it is not manufactured in the classical sense

3. Software doesn’t “wear out”

4. Most software is custom-built, rather than being assembled from e

xisting components

2.0 Software Myths

Myths are misleading attitudes that have caused

serious problems for managers and technical people.

However, old attitudes and habits are difficult to modify, and remnants of software myths are still believed.

There are three category of software myths:

Management Myth

Managers with software responsibility, like man

agers in most discipline, are often under pressure to maintain budgets, keep schedules from slipping, and often improve quality.

Software manager often grasps at belief in a software myth, if that belief will lessen the pressure.

Myth

·We already have a book that’s full of standards an

d procedures for building software. Won’t that provide my people with everything they need to know?

·My people do have state-of-the-art software development tools. After all, we buy them the newest computers

·If we get behind schedule, we can add more programmers and catch up. This is sometimes called the ‘Mongolian horde concept.

Customer Myth

A customer who requests computer software may be a person at the next desk, a technical group down the hall, the marketing/sales department, or an outside company that has requested software under contract.

In many cases, customer believes myths about software because software responsible managers and practitioners do little to correct misinformation. Myths lead to false expectations (by the customer) and ultimately dissatisfaction with the

developers.

Myth

·A general statement of objectives is sufficient to begin writing programs – we can fill in the details later

·Project requirements continually change,

but change can be easily accommodated because software is flexible.

Practitioner’s Myths

Myths that are still believed by software practitioners have been fostered by decades of programming culture.

During the early days of software, programming was viewed as an art.

Old ways and attitudes die hard.

Myth

·Once we write the program and get it to work, our job is done

·Until I get the program running, I really have no way of assessing its quality

·The only deliverable for a successful project is the working program

3.0 Software Components

·Algorithms

·Programming languages : Low level, High-level and Very-high level

·Non-procedural languages

·Language translators : Interpreters, Compilers

·Data Structures

·Library routines : Functions & Subroutines

4.0 Attributes of good software

5.0 Software Applications

·Software may be applied in any situation for which a pre-specified set of procedural steps (eg; Algorithms) has been defined. Information content and determinancy are important factors in determining the nature of a software application. Content refers to the meaning and form of incoming and outgoing information. Information determinacy refers to the predictability of the order and timing of information.

·The following software areas indicate the breadth of potential applications:

a)System Software

b)Real-time software

c)Business Software

d)Engineering and scientific software

e)Embedded software

f)Personal computer software

g)Web-based software

h)Artificial Intelligence software

6.0 Key Challenges Facing Software Engineering

·Software engineering in the 21st century faces three key challenges:

The legacy challenge: Challenge of maintaining and updating this software in such a way that excessive costs are avoided and essential business services continue to be delivered.

The heterogeneity challenge: Challenge of developing techniques to build dependable software which is flexible enough to cope with this heterogeneity

The delivery challenge: Challenge of shortening delivery times for large and complex systems without compromising system quality.

·Each of the above is not necessarily independent.

·For example, it may be necessary to make rapid changes to a legacy system to make it accessible across a network.

·To address these challenges, new tools and techniques are required as well as innovative ways of combining and using existing methods.

The problems with software

1.Poor quality systems

2.Non-conformance to requirements

3.High maintenance costs

4.Schedule overruns

5.Cost overruns

The reasons for the problems

1.Poor user requirement capture

2.The lifecycle forces the problems backwards

3.Maintenance has a low priority

4.Very little data collection

5.Very little or no QA

Introduction to Software Principles

2009-03-06T10:11:00.000-08:00

1.0 Introduction

· Computer software has become a driving force. It is the engine that drives business decision-making. It serves as the basis for modern scientific investigation and engineering problem solving. It is a key factor that differentiates modern products and services. It is embedded in systems of all kinds : transportation, medical, telecommunications, military, industrial processes, entertainment, office products …etc.

· Computer software is the product that software engineers design and build. It encompasses programs that execute within a computer of any size and architecture, documents that encompass hard-copy and virtual forms, and data that combine numbers and text but also include representations of pictorial, video and audio information.

· Today, software takes a dual role : It is a product and, at the same time, the vehicle for delivering a product.

2.0 Software Engineering

· Is an engineering discipline which is concerned with all aspects of software production from the early stages of system specification through to maintaining the system after it has gone into use. It is concerned with the practicalities of developing and delivering useful software.

3.0 Software Products

· Software Engineers are concerned with developing software products. There are two types of software product:

1. Generic products : These are stand-alone systems which are produced by a development organization and sold on the open market. Sometimes they are referred as ‘shrink-wrapped software’. Eg; databases, word processors, graphic packages etc. The organization which develops the software controls the software specification

2. Bespoke (or customized) products : These are systems developed specifically by a software contractor for a customer. Eg; Control systems for electronic devices, systems written to support a particular business process, air traffic control systems etc. The specification is usually developed and controlled by the organization (customer) buying the software

4.0 Software Process

· Is a set of activities and associated results which produce a software product. These activities are mostly carried out by software engineers. There are four fundamental process activities which are common to all software processes. These activities are:

1. Software Specification: The functionality of the software and constraints on its operation must be defined

2. Software development: The software to meet the specification must be produced

3. Software Validation: The software must be validated to ensure that it does what the customer wants

4. Software evolution: The software must evolve to meet changing customer needs

5.0 Process Maturity

· The Software Engineering Institute (SEI) has developed a comprehensive model that is predicted on a set of Software Engineering capabilities that should be present as organizations reach different levels of process maturity

· SEI uses an assessment questionnaire and a five-point grading scheme to determine an organizations current state of process maturity. The grading scheme determines compliance with a Capability Maturity Model (CMM) that defines key activities required at different levels of process maturity.

The SEI approach provides a measure of the global effectiveness of a company’s software engineering practices and establishes five process maturity levels, which are defined in the following manner

Multiple Document Interface (MDI)

2009-03-05T09:18:00.000-08:00

MDI Applications

MDI (Multiple Document Interface) Application is an application in which we can view and work with several documents at once. Example of an MDI application is Microsoft Excel. Excel allows us to work with several documents at once. In contrast, SDI (Single Document Interface) applications are the applications which allows us to work with a single document at once. Example of a single document application is Microsoft Word in which only one document is visible at a time. Visual Basic .NET provides great support for creating and working with MDI applications. In general, MDI applications are mostly used by financial services organizations where the user needs to work with several documents at once.

Creating MDI Applications

Let's create an MDI application. Open a new Windows Application in Visual Basic .NET. The application will open with a default form, Form1. Add another form, Form2 to this application by right-clicking on the project name in Solution Explorer window and selecting Add->Add Windows Form. You can add some controls to Form2. For this application we will make From1 as the MDI parent window and Form2 as MDI child window. MDI child forms are important for MDI Applications as users interact mostly through child forms. Select Form1 and in it's Properties Window under the Windows Style section, set the property IsMdiContainer to True. Setting it to true designates this form as an MDI container for the child windows. Once you set that property to true the form changes it's color. Now, from the toolbox drag a MainMenu component onto Form1. We will display child windows when a menu item is clicked. Name the top-level menu item to File with submenu items as New Child Window, Arrange Child Windows and Exit. The whole form should look like the image below.

With this application a new child window is displayed each time the New Child Window menu item is clicked, all child windows will be arranged when you click Arrange Child Windows menu item. To get the desired result, open the code designer window and paste the following code.

When you run the application and click "New Child Window" menu item, a new child window is displayed. Five child windows will be displayed as we declared an array of five in code. The image below displays the output.

When you click on "Arrange Child Windows" menu item, all child windows are arranged. It looks like the image below.

Creating Multiple Forms in VB .NET

It's a rare programme that only has one form in it. Most programmes will have other forms. These other forms can be used for things like Find and Replace searches, extra formatting capabilities, to set Options for the programme, and a whole lot more besides. VB.NET let's you add as many forms as you want to your project. But the process is not quite so simple. We'll see how to do it, though.
· Start a New project
· This will create a form called Form1
· To create a second form, click the Project menu
· From the drop down menu, click Add Windows Form
· The Add New Item dialogue box appears:

Loops

For Loop
The For loop is the most popular loop. For loops enable us to execute a series of expressions multiple numbers of times. The For loop in VB .NET needs a loop index which counts the number of loop iterations as the loop executes. The syntax for the For loop looks like thisThe image below displays output from above code.

While loop

While loop keeps executing until the condition against which it tests remain true. The syntax of while loop looks like this:

Example on While loop

Do Loop

The Do loop can be used to execute a fixed block of statements indefinite number of times. The Do loop keeps executing it's statements while or until the condition is true. Two keywords, while and until can be used with the do loop. The Do loop also supports an Exit Do statement which makes the loop to exit at any moment. The syntax of Do loop looks like this:

Example on Do loop

The image below displays output from above code

To stop the programme from running, you can do one of the following:

2009-03-02T06:22:00.000-08:00

1. Click the Red X at the top right of your Form
2. Click Debug > Stop Debugging from the menu bar
3. Press Shift + F5 on your keyboard

All right, we're getting somewhere. We now have a form with textboxes and labels, something that looks like a form people can fill in. But those labels are not exactly descriptive, and our textboxes have the default text in them. So how can we enter our own text for the labels, and get rid of that default text for the textboxes?
To do those things, we need to discuss something called a Property.
Properties
You have noticed the area to the right of the design environment, the area with all the textboxes in a grid, the one that has those daunting names like "AccessibleDescription", "AccessibleName", "AccessibleRole". That's the Properties box.
Click anywhere on the form that is not a label or a textbox, somewhere on the form's grey areas. The form should have the little sizing handles now, indicating that the form is selected.
On the right of the design environment there should be the following Properties box:

If your Properties box says "Textbox1 Textbox" or "Label1 Label" then you haven't yet selected the Form. Click away from the textbox or label until the Properties box reads "Form1 Form"
What you are looking at is a list of the properties that a form has: Name, , BackColor, Font, Image, Text, etc. Just to the right of these properties are the values for them. These values are the default values, and can be changed. We're going to change the value of the Text property.
First, you might want to display the list of Properties in a more accessible form. You can display the list properties alphabetically. To do that, click the Alphabetic icon at the top of the Properties box, as in the image below

This will make the properties easier to find.
Before we change any in the Properties box, let's clear up what we mean by "Property".
What is a Property?
Those controls you added to the form (textboxes and labels), and the form itself, are called control objects. You can think of controls as things, something solid that you can pick up and move about. Controls (things) have properties. If your television were a control, it too would have properties: an On/Off button property, a colour property, a volume property, and a ... well, what other properties would your television have? Think about it.
The properties of your television will have values. The On/Off button would have just two values - On or Off. The volume property could have a range of values, from zero to ten, for example. If the value of the volume property was set to ten, the loudest value, then you'd probably have some very angry neighbours!
In VB.NET, you can change a property of a control from the Properties Box. (You can also change a property using code, which you'll do quite a lot.) If we go back to our Form object, and the properties and values it has, we can see how to change them using the Properties Box. We'll change only one of these values for now - the value of the Text property . So, do this:
•Locate the word "Text" in the Property box, as in the image below

"Text" is a Property of Form1. Don't be confused by the word "Form1" next to the word "Text". All this means is that the current value of the Text property is set to the word "Form1". This is the default.
To change this to something of your own, do this:
•Click inside the area next to "Text", and delete the word "Form1" by hitting the backspace key on your keyboard
•When "Form1" has been deleted, type the words "My First Form"

•Click back on the form itself (the one with the labels and textboxes), or hit the return key on your keyboard
•The words "My First Form" will appear as white text on a blue background at the top of the form

As you can see, your new text has gone at the top of the form, in white on the blue background.
So the Text Property of a form is for setting the caption you want to display in the title bar at the top.
The Text Property
Changing the values of some properties is fairly easy. We'll now change the Text properties of our labels, and the Text properties of our Textboxes.
Click on Label1 so that it has the sizing handles, and is therefore selected. Examine the Property box for the Label:
You can see that the Label control has quite a few different properties to the Form control. Think back to your television as an control. It will have different buttons and knobs to your DVD Player control. A label has different "buttons and knobs" to the Form's "buttons and knobs".
But the Label has a lot of properties that are the same. The Text property of a Label does what you'd expect it to do: adds text to your label. We'll do that now:
•With label1 selected, click inside the area next to "Text", and delete the word "Label1" by hitting the backspace key on your keyboard
•Type in the words "First Name"
•Click back onto the grey form, or hit the return key on your keyboard
•Label1 has now changed its text caption to read "First Name"
•If you've made a typing error, go back to the first step above and try again
•Your form should now look like this:
Now, change the Text property of the other two labels. Change them to these values:
Label2: Last Name
Label3: Telephone Number
When Label3 has been changed, you might notice that the words "Telephone Number" won't fit on to the Label. That's because the label is too small, and needs to be resized. Drag the sizing handles out until you see both the words.
The form might look a little squashed, though. Is there anything we can do to make it bigger? Well, it just so happens there is.
The Form can be resized just like the Label and the textboxes. Click anywhere on the form that is not a textbox or a label. If you look closely around the Form's edges, you'll notice our old friends the sizing handles. To make the form bigger, just stretch them like you did the labels and the textboxes. Play around with the size of the form until you're happy with it. You can now reposition and resize the textboxes and labels so that things don't look too squashed. Your form might look like this one:

Click on Debug > Start to have a look at your programme. Or Press F5 on your keyboard. Click Debug > Stop Debugging to get back to the design environment. (Or press Shift + F5, or just click the red X at the top right of the form.)

Saving your work
If you have a look in the top right of the Design Environment, you'll see the Solution Explorer. (If you can't see it, click View > Solution Explorer.)

The Solution Explorer shows you all the files you have in your project (Notice that the name of your project is at the top of the tree - "My First Project"). But this is not the whole story. When you save your project, a lot of other files are also created. If you use Windows Explorer (part of the Windows Operating system, and not the VB NET software), you can see all those files

If you wanted to open up your project from here, you would double click the file called "First Form.vbproj".
In Visual Basic .NET an awful lot more files are created for a project than there are with Visual Basic 6. This is due to the Object Oriented nature of NET.
To actually save your work as you go along, do one of the following:
•Click File > Save All from the menu bar
•Press Ctrl + Shift + S on your keyboard
•Click the icon in the Toolbar (the stack of floppy disks)
If you save often then you won't lose any of your work if anything goes wrong with your computer.

Variables
Variables are used to store data. A variable has a name to which we refer and the data type, the type of data the variable holds. VB .NET now needs variables to be declared before using them. Variables are declared with the Dim keyword. Dim stands for Dimension.
Example

Data Types in VB .NET
The Data types available in VB .NET, their size, type, description are summarized in the table below.
Access Specifiers
Access specifiers let's us specify how a variable, method or a class can be used. The following are the most commonly used one's:
Public: Gives variable public access which means that there is no restriction on their accessibility
Private: Gives variable private access which means that they are accessible only within their declaration content
Protected: Protected access gives a variable accessibility within their own class or a class derived from that class
Friend: Gives variable friend access which means that they are accessible within the program that contains their declaration
Protected Friend: Gives a variable both protected and friend access
Static: Makes a variable static which means that the variable will hold the value even the procedure in which they are declared ends
Shared: Declares a variable that can be shared across many instances and which is not associated with a specific instance of a class or structure
ReadOnly: Makes a variable only to be read and cannot be written

Adding Controls Using the Toolbox

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Create two more textboxes by double clicking on the textbox icon in the toolbar (Or Right-click on the selected textbox and choose Copy. Then Right-click on the Form and choose Paste.)
Resize them to the same size as your first one
Line them up one below the other with space in between
Try to create something that looks like the one below

Adding a Label to your Form
Let's add some labels near the textboxes so that your users will know what they are for.
•Locate the label control in the toolbox
•Double click the label icon
•A new label is added to your form
•It should look like the one below

The square sizing handles are surrounding the label, and that indicates that a control is selected. Once a control is selected you can do things to it, like resizing the control or moving it.
•Move your Label to the left of the first textbox
•If the label stretches over the textboxes, resize it just as you did with the textboxes (You'll notice that the height of the label can be changed, unlike the textbox.)
.Create two more labels, and position them to the left of the textboxes.
•You should now have a form like this one

To see what your Form looks like as a programme, click Debug > Start from the menu bar. Or press F5 on your keyboard:

Adding Controls Using the Toolbox

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Things like buttons, textboxes, and labels are all things that you can add to your Forms. They are know as Controls, and are kept in the Toolbox for ease of use.
The Toolbox can be found on the left of the screen. In the picture below, you can see the toolbox icon next to Form1

To display all the tools, move your mouse over the toolbox icon. You'll see the following automatically appear:

There are five categories of tools available: Data, Components, Windows Forms, Clipboard Ring, and General. The toolbox you'll be working with is the Windows Forms toolbox. To see the tools, click on the words "Windows Forms". You'll see a long list of tools:

As you can see, there are an awful lot of tools to choose from! Click the black arrow, and scroll down to see even more. For this first section, we'll only be using the ones at the top: the Button, the TextBox and the Label.
If you want to keep the toolbox displayed, click the Pin icon next to the X. To close the toolbox, simply move your mouse away.
In the next part, we'll see how to add a textbox to the form.

Adding a Tool (Control) to your Form

Let's start by adding a textbox to our form. With the tools displayed, do the following:
•Locate the TextBox tool
•Double click the icon
•A textbox is added to your form
The textbox gets added to the top left position of your form. To move it down, hold your mouse over the textbox and drag to a new position

Notice the small squares around the textbox. These are sizing handles. Move your mouse over one of them. The mouse pointer turns into an extended line with arrowheads. Hold your left mouse button down and drag outwards. The textbox is resized. Play around with the sizing handles until you're happy with the size of your textbox.
One thing you will notice is that you can't make the size any higher, but you can make it wider. The reason why you can't make it any higher is because the default action of a textbox is to have it contain only a single line of text. If it's only going to contain one line of text, Microsoft reasoned, there's no reason why you should be able to change its height. A textbox can only be made higher if it's set to contain multiple lines of text. You'll see how to do this soon.
You should now have a textbox on your form that looks something like this one:

Understanding VB.NET Development

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At the bottom of the screen, there are two buttons: "New Project" and "Open Project". To get started, click the "New Project" button. When you do, you'll see this dialogue box appear:

If you look in the Name textbox at the bottom, you'll see it says "WindowsApplication1". This is the default name for your projects. It's not a good idea to keep this name. After all, you don't want all of your projects to be called "WindowsApplication1", "WindowsApplication2", etc. So click inside this textbox and change this Name to the following:
My First Project
Keep the Location the same as the default. This is a folder inside of your "My Documents" folder called "Visual Studio Projects". A new folder will then be created for you, and its name will be the one you typed in the "Name" textbox. All of your files for your first project are then saved in this folder.
Click the OK button, and the Visual Basic NET design time environment will open.
In the Visual Basic NET design time environment, the first thing to concentrate on is that funny grey square with all the dots on it. That's called a form. It's actually the pretty bit of your programme, the part that others will see when they launch your masterpiece. Granted, it doesn't look too attractive at the moment, but you'll soon discover ways to lick it into shape. Here's what it looks like:

In case you're wondering what those little dots are for, they are there purely for your benefit. They allow you to align things like textboxes and labels with a degree of precision. They won't appear when you run the form. If you don't believe me, try this:
•From the menu bar, click Debug
•From the drop down menu, click Start
•Alternatively, press the F5 key on your keyboard
•Your programme is launched
Congratulations! You have now created your very first programme. It should look like this:

As you can see, all of the dots are gone!
Click the Red X on the form to stop it from running. You will then be returned to the form with the dots on it.
If you compare the first form with the one above, you'll see they look quite different. That's because the one above is actually a real programme, something you could package and sell to unsuspecting village idiots.
So what's going on? Why the two different views? Well, Visual Basic has two distinct environments, a Design environment and a Debug environment. Design Time is where you get to play about with the form, spruce it up, add textboxes, and buttons, and labels (and code, of course ); Debug is where you can test your programme and see how well it performs. Or doesn't perform, as is usually the case.
But don't worry about the terminology, for the time being. Just be aware that there's a two step process to VB programming: designing and debugging.
So, let's get on and do some designing! Before we can start designing a form, though, we need some tools. And where are tools kept? In a toolbox!

How To Name Controls?

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Name the controls with three-letter prefix that helps identify what kind of control is in use. Use unabbreviated words with mixed case to complete the name, eg frmPropertiesCheck. Table 1.1 below lists standard prefixes for commonly used controls.

What is Event-Driven Programming?

Whenever any user action occurs in an application, Windows generates one or more messages that are sent to the application. This is called Windows messaging. User actions are called events, like clicking a button that fires a click event in Visual Basic and if the user presses the spacebar, the KeyPress event is fired. The programmer must handle the event by writing code (explicit instructions) that specifies how to handle the user action or event. This code, called an event procedure or a method, is written in an object’s code window.

How to Run and Test Programs?

The easiest way to test is to simply run the program. The system then builds a solution by converting your code and form design into executable code. As a part of the build process, errors may be identified. Once the solution is built and contains no errors, you can then run it.

Program can be run with or without the Debugger. The Debugger is helpful in finding problems with the program code.

SUMMARY

• Microsoft Visual Basic .NET is a set of programming tools that allows you to create applications for the Windows operating systems and for Internet.
• Programs in Visual Basic are event-driven. User initiates an event by clicking the mouse or pressing a key.
• The code written by a programmer to respond to an event is called a method.
• The Solution Explorer lists all files and modules that make up an application. It may contain information about more than one project.
• A Toolbar provides easy access to frequently performed commands. A number of specialized toolbars can be displayed to make other commands readily available.
• The Toolbox initially contains many controls that you can add to your forms. More controls can be added to the Toolbox that offers greater capabilities.
• The Properties windows list the properties information for a selected form or object.
• Standard prefixes have been developed for naming commonly used controls.
• It is important to give descriptive name to all objects. Build the names with appropriate three-letters prefix followed by one or more words starting with uppercase letters. The word(s) should describe the control’s use.
• A Visual Basic project consists of all forms, controls, code, and other items that make up an application. Use the Solution Explorer to views those components.
• Programs in Windows are based on messages that generate events for the application. Each event executes code contained in the event’s method

Exercise

1. When a user clicks the mouse or keys in a letter it is called a(n) _____________.

2. Code executed when an even occurs is called a(n) ________________.

3. To run a program in Visual Basic, you can select an item from the ___________ menu.

4. An input box is used to collect ______________ from the user to use in the program.

5. One way to obtain “context-sensitive” help is to select a keyword, property, or control and press the _______________ key on the keyboard.

6. GUI stands for _______________________________________ .

7. IDE stands for _______________________________________ .

8. The form is sometimes called the _____________________ of a project, because the user interacts with the application through the form.

9. The Solution Explorer window lists all ____________ and ______________ used in the project or projects

This is how a basic empty VB.NET IDE will look like.

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Figure 1

It is important to understand the functions of all the elements in the IDE

Elements are:

1.MenuBar : common to any Windows application. Listing all action that can be performed.
2.ToolBar : common to any Windows application. Shortcuts to actions in Menubar.
3.Solution Explorer : lists all forms and modules used in the project or in the projects that make up the complete application.
4.Properties Window : to view and make changes to the properties of the objects in the application.
5.ToolBox : contains all the control that can be implemented in a development of an application
6.Form : can be Windows forms or Web Forms. The interface of a system with the user.

INTRODUCTION TO MS VB.NET PROGRAMMING CONCEPTS

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.NET Defined

Before getting deeply into the subject we will first know how Businesses are related to Internet, what .NET means to them and what exactly .NET is built upon. As per the product documentation from a Business perspective, there are three phases of the Internet. The First phase gets back to the early 1990's when Internet first came into general use and which brought a big revolution for Businesses. In the First phase of the Internet Businesses designed and launched their Website's and focused on the number of hits to know how many customers were visiting their site and interested in their products, etc. The Second phase is what we are in right now and in this phase Businesses are generating revenue through Online Transactions. We are now moving into the Third phase of the Internet where profit is the main priority. The focus here is to Businesses effectively communicate with their customers and partners who are geographically isolated, participate in Digital Economy and deliver a wide range of services. How can that be possible? The answer, with .NET.

What is .NET ?

Many people reckon that it's Microsoft's way of controlling the Internet, which is false. .NET is Microsoft's strategy of software that provides services to people any time, any place, on any device. An accurate definition of .NET is, it's an XML Web Services platform which allows us to build rich .NET applications, which allows users to interact with the Internet using wide range of smart devices (tablet devices, pocket PC's, web phones etc), which allows to build and integrate Web Services and which comes with many rich set of tools like Visual Studio to fully develop and build those applications.

Microsoft Visual Basic allows us to create professional looking applications for Windows and Internet pretty much very easily. The graphical user interface (GUI) lets the text and graphics communicate with the computer.

1.1 What’s VB.NET?

VB.NET is the following version of VB 6.0. Microsoft .NET is a new programming and operating framework introduced by Microsoft. All .NET supported languages access a common .NET library to develop applications and share common tools to execute applications. Programming with Visual Basic using .NET is called VB.NET. Visual Basic .NET is a major component of Microsoft Visual Studio .NET suite. The .NET version of Visual Basic is a new improved version with more features and additions. After these new additions, VB qualify to become a full object-oriented language such as C++.

1.2 What is IDE?

An integrated development environment (IDE), also known as integrated design environment and integrated debugging environment, is a type of computer software that assists computer programmers to develop software.IDEs normally consist of a source code editor, a compiler and/or interpreter, build-automation tools, and (usually) a debugger. Sometimes a version control system and various tools to simplify the construction of a GUI are integrated as well.

Visual Basic is a Windows development language, thus it is importanat to be familiar with th ecommon features found in Windows applications. A user is expected to see items such as menus, toolbars, and Minimize and Maximize buttons.