Software Engineering Aspects of Web Based Development Cathy Huttenhoff Software Engineer Senior Seminar Fall 2009

Abstract Initially there was no need for web development because there was no such thing as the internet. But as this was created, the need for a new form of development grew. This form of development corresponded to the new form of programming. In order for a program to be written using software engineering, it must follow a software development process. There are several processes to choose from and each is different. The processes used to create web pages and web applications are similar to the ones that were originally used to develop other programs but have crucial differences including software security, load issues and security.

Overview Background Concurrency Unpredictable Load Security Multi-Modal Interface Software Engineering Process

Background Internet  Grew to popularity in the 1990s Old model didn't take into account new demands New demands  Concurrency  Unpredictable loads  Security  Multi-Modal Interface

Concurrency Originally only one user at a time. Some lag acceptable. Only a few commands at a time. Now many users at once. Users demand less lag time. Now the few commands multiplied by many users.

Unpredictable Load Websites don't know how many viewers/users they will have.  Could have 100 today  And 100,000 tomorrow System must be able to handle loads of any size. Visitor count  Int overflow Twitpocalypse

Security Physical access vs. Remote Access Malicious Programs  Virus  Worms  Spyware Microsoft Windows  Release patches for security Financial Transaction  Don't want personal information stolen.

Multi-Modal Interface “Multimodal interfaces process two or more combined user input modes, such as speech, pen, touch, manual gestures, and gaze, in a coordinated manner with multimedia system output.” People want more technology. People want to be able to do more on their technology.  Web pages on Blackberries & Cell Phones

Software Engineering Process Requirements Design Implementation Verification / Testing Maintenance Figure 1 : Waterfall Method

Requirements Speed Concurrency Different numbers of users User Interface  Purchaser of software will be especially concerned about this.

Design Low coupling  Different parts of a system  Different pages of a website Store information on users computer vs. in master database Independent parts using cookies

Cookies In computing, a cookie is a small piece of text stored on a user's computer by a web browser. A cookie consists of one or more name-value pairs containing bits of information such as user preferences, shopping cart contents, the identifier for a server-based session, or other data used by websites. It is sent by a web server to a web browser and then sent back unchanged by the browser each time it accesses that server.

Implementation Transforming diagrams into the base code. Create a Graphical User Interface (GUI)  Put code a methods into that page  Post back vs not post back Web development environment vs by hand  Visual Studios.Net  DreamWeaver

Testing Black box vs. White box  Easier to test Beta versions  Open up to users  Get public to do testing  Only need an internet connection  No special software to install Good bug tracking system  Online

Maintenance Easier to offer tech. support  Only one version  Don't have to support multiple versions Easier to fix bugs  When a bug fix is found, then the page is updated  Don't have to wait for the next patch release date

Conclusion New Demands  Concurrency  Unpredictable Load  Security  Multi-Modal Interface Software Engineering Process  Requirements  Design  Implementation  Verification / Testing  Maintenance

Questions?

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