Typical Student-Oriented SIS Web Application Profile

This "typical" profile is compiled from responses provided to questions listed in the Making Design Decisions section of the companion document to this one, Object Oriented Development Methodology. This profile is not meant to describe the universe of SIS applications; it does describe a subset that makes up a large fraction of SIS projects. Other sections (to be completed) in this document will address other categories of SIS applications.

For "typical" student-oriented web applications implemented by SIS:

• A browser-based UI is preferred and appropriate
• Functionality includes retreival, insertion, and update of persistent data within constraints of business rules.
• The universe of potential users is about 40,000; high concurrent usage occurs for a small but critical subset of these applications
• A workflow component, high-usage periods, and/or time-window restrictions are common
• Application is inward-facing (access intended for UCB community members of varying roles)
• Role-based security and finely-grained permissions often apply
• Application is mission-critical
• Application is expected to have a long lifespan (15-30 years)

Technology Stack

The technology stack summarized in the chart below, and described in the following sub-sections is appropriate to the application profile described above.

Deployment Environment

Technology

JBoss, Apache HTTP Server

Comments

• JBoss includes an embedded Apache-Tomcat servlet container. It is selected in order to provide configurable (via the JMX micro-kernel) container services (e.g., connection pooling, transaction management, JMS, JNDI, web-services, etc.).
• Apache is deployed in front of the application server to:
  • handle SSL (https) more elegantly than the application server;
  • serve static content without engaging the application server (for better appliation performance); and,
  • to relieve the user of the need to use a port number in the application URL

Other Technologies Considered

Future Directions

View Layer

Technology

CSS, JSP, JSTL, XSLT, & JSF

Comments

• CSS - efficient, object-oriented HTML styling (UI look & feel)
• JSP - integration of HTML markup with back-end data & business logic functionality
• JSTL - JSP Standard Tag Library encapsulates common web application functionality as a set of simple tags.
• XSLT - where multiple output-targets or rendering modes are required
• JSF - A technology to move toward for its event-driven callback architecture, which more closely and elegantly mimics desktop GUI programming within a web-browser context; and because excellent visual-programming tools for this technology are being implemented.

Other Technologies Considered

Future Directions

Web Application MVC Layer

Technology

Spring

Comments

This is choice of the Sakai project, toward which SIS is aiming new development projects.

Other Technologies Considered

Struts - used successfully in SIS, but not Sakai choice

Future Directions

Beehive is a new Apache project that is likely to evolve into a more robust MVC framework for web applications and web services.

Business Logic Layer

Technology

• EJB session & message-driven beans
• POJOs ("plain old Java objects") - business logic implemented in easily repurposable classes

Comments

A thin EJB session-bean facade to leverage container services (pooling, etc.); while business logic itself is delegated to POJO ("plain old Java objects") that can be repurposed easily behind alternate facades as need dictates. Message-driven beans for asyncronous functionality.

Other Technologies Considered

Future Directions

Persistence Layer

Technology

Hibernate

Comments

• This is choice of the Sakai project, toward which SIS is aiming new development projects.
• EJB 3.0 entity beans will converge with Hibernate

Other Technologies Considered

EJB entity beans - used successfully by SIS, but not a good technology in which to invest at this time given Sakai choice and future direction of EJB specification (v. 3.0 is expected to look much like Hibernate).

Future Directions

Workflow Layer

Technology

Message-driven Beans (JMS)

Comments

Loosely coupled, reliable, and asynchronous communication between message-driven EJBs (cf. this definition of message-driven beans).

Other Technologies Considered

Future Directions