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Stanford University CourseWork


Technical Overview back to index



1. Overview


CourseWork is a Java Servlet Web Application which provides course management services, including a coursehomepage, syllabus, announcements, schedule, on-line course materials, assignments, discussion boards, and a gradebook. This document describes the basic system architecture of the current implementation of CourseWork at Stanford University.

The CourseWork application is comprised of two tiers:

1) A servlet-based Web Application running under Apache Tomcat.
2) An Oracle 8i database.

Java Servlet Engine:
We are utilizing Apache Tomcat 3.2.3 as our Java Servlet engine. CourseWork has been tested using both Java 1.3 and Java 1.4.

SQL Database Component:
The database component of CourseWork was designed to run as a single user schema inside an Oracle 8i instance. We are currently using Oracle 8.1.7.

We are using the JDBC drivers which come with Oracle 8.1.7. We have used both the Thin driver and the OCI-8 driver. These drivers are contained in the file classes12.zip which comes with Oracle 8.1.7. We repackaged these as a JAR file to include inside the /lib directory of our web app, though that is not absolutely necessary if you want to manually adjust your CLASSPATH to include the zip file.

2. SQL Database

Coursework is supported by a single SQL database schema. The schema can be divided into a "Core" set of tables used by the entire CourseWork application, and individual sets of tables used by each tool.

Database schemas can be found here.

3. Web Application

The CourseWork web application is distributable as a single WAR (web application archive) file. We build the WAR file using the Apache Ant tool. The web application is comprised of a set of servlets, supporting Java packages, a library of JAR files, configuration files, static HTML files, and a set of templates which control the user interface for the application. These templates are used in conjunction with a templating engine called "Dynamic Templating Language", or DTL, that was developed here at Stanford University by Highwire Press. DTL will be discussed in more detail later in this document.

The CourseWork developer directory has the following structure:

/conf - configuration files for developer webapp
/devprodconf - conf files for the prod webapp on your dev server
/preprodconf - conf files for the preprod server
/prodconf - conf files for the production server(s)

/etc - web.xml file
/dtl - dtl templates
/lib - 3rd party JAR files
/src - CourseWork Java code
/web - static HTML files
build.xml - Ant build specifications
build - Ant build file

4. Java Code

The CourseWork Java code includes servlets and supporting Java packages.

A. Servlets
Several servlets control core functionality of CourseWork - creating and editing courses, site-level user administration, etc. These servlets include:

  • AdminCourse.java
  • AdminSite.java
  • AdminSitePerson.java
  • AdminTools.java
  • Bookmarker.java
  • CopyCourse.java
  • SessionTrack.java
  • DTL.java
  • MyCourses.java
  • MyProfile.java
  • Login.java
  • Logout.java

The remainder of the servlets are Tool servlets. Each tool typically has two servlets - the student view, <tool>.java, and the Admin View, Admin<tool>.java. For example, the Announcements tool is composed of Announcements.java and AdminAnnouncements.java.

B. Core Packages
The supporting Java packages are all under edu.stanford.coursework.*

There are two "core" packages which support core functionality throughout the CourseWork system: edu.stanford.coursework.core and edu.stanford.coursework.common. "Core" contains the four main objects for CourseWork - Nexus, Person, Tool, and Content. The Nexus object represents a course, a section of a course, or a department. The Person object represents a user of CourseWork. The Tool object represents a tool in the CourseWork system (as represented by a button in the NavBar). Finally, the Content object represents a single piece of content (either an uploaded file or a URL) used in CourseWork. Person, Tool, and Content objects can all be associated with one or more Nexus objects (except Content objects where the relationship is always to a single Nexus).

Most objects in CourseWork, including these core objects, have three associated java classes - the object, a controller, and an SQL file. The object contains constructor methods, get and set methods for each field, and a "toDTLObject" method which creates a DTL object from the object. The Controller class contains static methods to get, create, save, remove objects from the database, as well as other methods to manipulate objects. The SQL class contains static string fields for each of the SQL query statements used in preparedStatements to execute database transactions. For example, the Person object model is comprised of "Person.java", "PersonController.java" and "PersonSQL.java".

The
edu.stanford.coursework.common package contains other objects used throughout the CourseWork system besides the four core objects. These include an abstract "BaseServlet" class, a SessionController to read and modify a user's HttpSession, and the NavTrail object used to construct the "bread-crumb" trail at the top of each CourseWork page.

C. Tool Packages
Each tool also has an associated package:

  • edu.stanford.coursework.coursehome
  • edu.stanford.coursework.announcements
  • edu.stanford.coursework.syllabus
  • edu.stanford.coursework.schedule
  • edu.stanford.coursework.coursematerials
  • edu.stanford.coursework.assignments
  • edu.stanford.coursework.discussion
  • edu.stanford.coursework.grades

To create a new tool for CourseWork would require the introduction of a new package for the tool as well as the student and admin view servlets.

The object model used in the current CourseWork tool follows very closely the object model for the core objects, eg, Announcement.java, AnnouncementController.java, AnnouncementSQL.java.

For more information on particular Java packages, please consult the CourseWork Javadocs.

5. Dynamic Templating Language (DTL)

CourseWork utilizes a Java-based system called Dynamic Templating Language, or DTL, to render all HTML output. DTL was developed at Stanford's Highwire Press (www.highwire.org) and is included as part of the open source distribution of CourseWork as a JAR file (lib/dtl.jar). DTL allows the CourseWork code to create DTLObjects from regular Java objects and pass these to a DTL template, where tags within the template get replaced by the DTLObject variable definitions to create HTML output. DTL is extremely fast and efficient and contains rich functionality for doing variable replacements.

EXAMPLE:

[[VARDEF $COLOR]]#CCCCCC[[/VARDEF]]
This font color is <FONT COLOR=[[$COLOR]]>grey</FONT>.

Or in Java Code:
DTLObject mainDTL = new DTLObject();
mainDTL.put(“COLOR”, “#CCCCCC”);

For more instructions for how to use DTL, the following are available:

 


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