Design of Web-based Systems IS Development: lecture 10

Hardware of web-based systems Database and other computing resources Users directly accessing organisational resources Web server, including an organisation’s web pages. Sources of data for use via the web pages.

Software of web-based systems Browsers (can handle processing within web pages, e.g. using Javascript) Web server software Database connectivity e.g. ODBC Data in databases Can include scripts for linking databases to the web, e.g. ASP.

The distinctiveness of the web Data use not contained purely within organisational boundaries. Client-server model taken to an extreme - processing can take place on the browser or on the host computer. Requires extra software to link databases to the web and browsers to internal IS

Issues for Design of Systems Management of the interaction between analysts, developers and graphic designers. How much processing should take place on the client side, how much on the server side? How can the architecture of systems with many links be given a formal design?

Issues for the design of classes Web pages can be treated as boundary classes (like GUIs): but can also implement business rules (e.g. through Javascript). Forms and form elements can also be classes (aggregation relationship with web page). Form elements linked to server pages (also classes).

Business Objects Database design Design of Client Pages Design of Server Pages Design activities for web-based systems

Designing a Systems Architecture Appreciating how a whole web site links together. Analysing the need, if any, for external links. Documenting the links and how they are related to pages.

Role of UML techniques in web design (1) Understand system functionality: use case models. Build business classes and relationships: class diagram. Integrate web pages as boundary classes (incl. graphic design): architecture modelled as class diagram

Role of UML techniques in web design (2) Integrate server pages on to the class diagram Develop user interactions with the web site as sequence diagrams

One possible set of relationships Request submitted from form to server page. Server page runs a query with output to client page