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Eclipse: The Story of Web Tools Platform 0.7
J2EE Development the Eclipse Way - Its Scope, Design Principles, Architecture, Ecosystem, and Plans
By: Arthur Ryman
Oct. 19, 2005 08:30 PM
Finally, we're ready to run the JSP. Select hello-world.jsp in the Project Navigator and the Run on Server command from the context menu. You'll be prompted to define the server to be used for the project since this is the first launch. Select the Tomcat server you previously defined and make it the project's default. The Web1 module will be added to the server configuration and the server will start. A Web browser will then be launched with the URL for hello-world.jsp. Figure 4 shows the Web browser with the Web page generated by hello-world.jsp.
Debugging JSPs is also simple. To demonstrate debugging, let's add a Java scriptlet to the JSP. The scriptlet will retrieve a query parameter named "user" and display a welcome message. Listing 1 shows the modified JSP that includes the Java scriptlet.
Set a breakpoint on the line that begins String user = by double-clicking in the left margin. Select the file hello-world.jsp in the Project Explorer and invoke the Debug on Server command from the context menu. The server will restart in debug mode and the Debug Perspective will open with execution halted at the breakpoint. Figure 5 shows the Debug perspective when the JSP is passed the query parameter user=JDJ readers on the URL.
You can now step through Java scriptlets and explore Java variables as usual. In Figure 5, the variable user has been selected in the Variables view that shows its current value JDJ readers. Click the Resume icon to finish processing the JSP. Figure 6 shows the Web browser displaying the resulting Web page.
WTP 0.7 Features
The server tools let you define and control servers. Servers can be associated with projects, and can be started, stopped, started in debug mode, and controlled in other ways. Projects can be deployed to servers, or servers can be configured to access your Eclipse workspace content directly. WTP includes server support for Apache Tomcat, Apache Geronimo, and JBoss, as well as many other popular commercial and Open Source J2EE application servers. The server tools include an extension point so that new server types can be easily supported. You can add a new server type by providing either a simple XML configuration file or a Java plug-in.
The XML tools include source editors for XML, DTD, and XSD that are based on the SSE Framework. Besides source editing, graphical editing is also provided for XSD. The XML tools also include code generators for creating XML instance documents from DTD or XSD.
The Web Service tools include a WSDL editor, a Web Service Explorer, a Web Services Wizard, and WS-I Test Tools. The WSDL editor includes an SSE-based source editor and a graphical editor. XSD editing is seamlessly integrated with WSDL editing. The Web Service Explorer lets you search and publish to UDDI registries, and dynamically test WSDL-based Web Services. The Web Service Wizard ties together the full development lifecycle. It lets you deploy Java classes as Web Services, generate server and client code from WSDL, and generate test clients, as well as being integrated with the Web Service Explorer for publishing and discovery. The Web Service Interoperability (WS-I) Test Tools let you validate WSDL and SOAP for compliance with the WS-I profiles.
The J2EE tools let you create J2EE projects and artifacts like JSPs, servlets, and EJBs, as well as the J2EE deployment descriptors, and deploy these to app servers. The J2EE tools have an SSE-based JSP source editor and a J2EE Project Navigator that displays J2EE components as objects. This provides a higher-level view of your project resources, for example, by displaying all the files related to an EJB as a single EJB object.
The data tools include support for connecting to JDBC-based databases such as Cloudscape, Derby, and other commercial and Open Source databases, and exploring their tables. The data tools also include an SQL source editor that lets you easily execute SQL statements and view the results.
The WTP Noosphere
WTP components are organized along the lines of open standards. WTP classifies the world of standards along two dimensions - technology and formality.
The technology dimension ranges from neutral standards on one extreme to J2EE standards on the other. Technology neutral standards form the foundation of the Web. In fact, the Web has succeeded because it's defined in terms of formats (such as HTML and XML) and protocols (such as HTTP) that specify how systems interact, but don't specify how systems are implemented. This neutrality has allowed vendors to choose the most appropriate implementation technology and compete on the basis of the quality of their implementations. On the other hand, J2EE standards specify application portability rules for J2EE implementations. Both kinds of standard are essential for the viability of the Web.
The formality dimensions define how the standards are created. At one extreme we have the de jure standards bodies such as ISO and IEEE and at the other we have technologies that aren't associated with any formal standards definition organization, but have become de facto standards because of their popularity. Organizations such as W3C, OASIS, and JCP, which define the standards relevant to WTP, have formal processes and are near the de jure end of the spectrum. Popular Open Source technologies such as Struts and Hibernate are at the de facto end.
Figure 7 shows the world of standards classified along the technology and formality dimensions. The turf of WTP is, in principle, all the important standards that are relevant to Web application development. However, the charter of WTP focuses on the standards that are formally defined by recognized standards-definition organizations, i.e., those that cluster towards the de jure end of the spectrum. WTP consists of two sub-projects, Web Standard Tools (WST) and J2EE Standard Tools (JST) that cover the formally defined Web and J2EE standards.
The reasoning behind this scope is that WTP aims to be a platform that many vendors can build on. The formal standards form the building blocks that most vendors want. Support for this base layer of standards is, in a sense, the "table stakes" of any tool. Vendors can cooperate on this base layer and produce high-quality common components while sharing the development expense. Conversely, by not including the de facto standards, WTP leaves room for vendors to innovate and differentiate. For Open Source to succeed contributors must have a way to generate a profit otherwise they won't be able to continue contributing. We hope that this design will yield an excellent set of core Open Source J2EE tools for users, and a solid platform that supports a thriving aftermarket of extenders.
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