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The latest version of IBM® WebSphere® Application Server -- Version 5.0.2 -- supports Web services in the Java™ 2 Enterprise Edition (J2EE) environment as defined by Java Community Process specifications JSR-109 and JSR-101. The latest version of WebSphere Studio Application Developer -- Version 5.1 -- supports WebSphere Application Server V5.0.2 and development of Web services for J2EE. This series of articles examines the support for J2EE Web services available in Application Developer V5.1 through a number of examples, with emphasis on the new level of support. Part 1 (this article) examines support for the server environment, while Part 2 examines support for the client environment.
The most important goal of Web services is interoperability. Perhaps the most important goal of J2EE is portability. The JSR-109 specification, "Web Services for J2EE, Version 1.0" produced by the Java Community Process (for more information, see Related Content), combines these two important goals for the J2EE environment. JSR-109 identifies the various roles and responsibilities required in producing and consuming Web services, the programming model and APIs for both the client and server, and the various artifacts required to support Web services for both the client and server. JSR-109 leverages the JAX-RPC or JSR-101 specification, "Java API for XML-Based RPC," to define parts of the overall J2EE environment, such as APIs and marshalling and unmarshalling. An excellent introduction to JSR-109 and JSR-101 can be found in the article Build interoperable Web services with JSR-109. In the rest of this article, "JSR-109" refers to content in either JSR-109 or JSR-101.
Particularly interesting is that JSR-109 defines two means for implementing a Web service which runs in a J2EE environment. The first extends the JSR-101 programming model, which defines a Web service as a Java class running in the Web container. The second uses a constrained implementation of a stateless session EJB in the EJB container. We will examine both means in this article.
Web services in Application Developer V5.1
Application Developer has supported Web services development since its introduction. Version 5.1 marks the first time, however, that support could be based on accepted specifications for the Java and J2EE environments which Application Developer targets, and it offers full support for JSR-109, both server and client. As with earlier versions, Application Developer 5.1 provides wizards for producing the server-side and client-side artifacts for Web services; it also includes specialized editors to manipulate some of the new J2EE Web services artifacts such as the server-side and client-side deployment descriptors. In this article, we will examine only the server-side tooling.
In addition to support for J2EE Web services, Application Developer includes support for the guidelines produced by the Web Services Interoperability Organization (WS-I). In particular, Application Developer is cognizant of WS-I's Basic Profile 1.0. For example, Application Developer supports the production of the document-literal and RPC-literal bindings as well as the more traditional RPC-encoded binding.
We will now look at examples that encompasses of server side development of Web services with Application Developer V5.1. We will focus on the differences from previous versions of the tool that result from support for JSR-109 or WS-I. The examples assume familiarity with basic Application Developer tasks such as creating projects of various types, creating and editing files of various types, running various wizards, including older versions of Web services wizards. If you are not familiar with such tasks, the help provided by Application Developer is quite extension and should assist you in getting started. You can also refer to articles on earlier versions of the tool. See the Resources section for more information.
The first example examines the process for turning a JavaBean into a Web
service in the Web container, to be consistent with earlier Web services
examples. The basic JavaBean we will use is a simplistic implementation of
ubiquitous stock quote service, and is shown in the following code
segment. The StockFullQuote JavaBean uses as a
return value what JSR-101 calls a "value type" data bean called
FullQuote, also shown in the code segment. For
use with the EJB example later in the article,
FullQuote must be serializable.
package wstest;
import java.util.Random;
public class StockFullQuote {
Random r = new Random();
public FullQuote getQuote(String symbol) {
int base = r.nextInt(100);
return new FullQuote(symbol, base+2, base+3, base+1);
}
}
package wstest;
public class FullQuote implements java.io.Serializable {
private String symbol;
private float current;
private float high;
private float low;
public FullQuote() {
}
protected FullQuote(String s, float c, float h, float l) {
symbol = s;
current = c;
high = h;
low = l;
}
public float getCurrent() {
return current;
}
public float getHigh() {
return high;
}
public float getLow() {
return low;
}
public String getSymbol() {
return symbol;
}
public void setCurrent(float float1) {
current = float1;
}
public void setHigh(float float1) {
high = float1;
}
public void setLow(float float1) {
low = float1;
}
public void setSymbol(String string) {
symbol = string;
}
} |
We will first create a Web project in which to develop and deploy the Web service. Application Developer allows two different forms of Web project; static Web projects are optimized for projects that contain static content such as HTML files; dynamic Web projects can contain dynamic components such as servlets and JSPs. We must create a dynamic Web project; we will call it "Services." Next we add the two JavaBeans described above the in the 'wstest' package to the Services project. When complete, the Navigator view of the Web perspective should look like Figure 1.
Figure 1. Services project after JavaBean creation
Next, we will use the new Web Services Wizard to turn the
FullStockQuote bean into a J2EE-compliant Web
service and generate all the necessary artifacts for deployment. As with
earlier versions of Application Developer, we start the wizard by
right-clicking on the StockFullQuote bean, then
selecting New => Other => Web Services => Web
Service => Next. The first panel of the wizard, named Web
Services, is the same as the previous versions of Application Developer;
you can simply click Next. In the next two panels, Service
Deployment Configuration and Web Service JavaBean Selection, all the
defaults are acceptable, so click Next in each. You should now see
the Web Service JavaBean Identity panel, shown in Figure 2.
Figure 2. Web Services Wizard: Web Service JavaBean Identity
Figure 2 contains the first indication of the support for J2EE Web services. In the Style and Use section of the panel, there are three combinations of style and use: Document/Literal and RPC/Literal are the two acceptable to WS-I, while RPC/Encoded is retained for older style Web services interactions. If we select either of the first two options and click Next, the wizard proceeds normally. If we select RPC/Encoded, however, the warning shown in Figure 3 is displayed to indicate the potential for interoperability problems due to the lack of compliance with WS-I. Instead, we select Document/Literal and click Finish to complete the creation of the Web service.
Figure 3. Web Services Wizard: Interoperability Warning
The Web services wizard proceeds to create all of the artifacts necessary for a J2EE Web service. Figure 4 shows the Navigator view of the Web perspective after the wizards has completed. The wizard has created the following Java classes:
- StockFullQuote_SEI
- This class defines the JSR-109 service endpoint interface (SEI) for
the Web service. It can be used by the client, or by implementers
trying to produce other implementations.Per JSR-109, the interfaces
extends
java.rmi.Remoteand has the same methods as the Web service JavaBean, in this casegetQuote(). - FullQuote_Deser, FullQuote_Ser, FullQuote_Helper
- These utility classes serve to allow Web service engines deserialize
and serialize the
FullQuoteJavaBean. The first two actually do the (de)serialization and the third is used to "find" the serializers and deserializers. These three utility classes are not mandated by JSR-109, but they are used by the WebSphere Web services runtime. While they are not referenced in any of the other artifacts, the runtime infers the class names from schema information in the WSDL file. If there were other complex data types in the SEI, the wizard would produce corresponding utility classes for them as well.
Figure 4. Services project after Web service creation
The wizard also produces a WSDL file for the Web service and, per JSR-109,
places it in the WEB-INF directory. The wizard
puts a copy of the file in a WSDL directory under Web Content for use by
other Application Developer tools like the WSDL Browser. If you open the
WSDL file StockFullQuote.wsdl, by default you
will open it with the new WSDL Editor. Figure 5 shows the graphical pane
of results of opening that file; Figure 5 does not show the lower panes of
the editor that offers textual details when you click on items in the
graph.
Figure 5. WSDL Editor showing StockFullQuote.wsdl
You can double click on the right-pointing blue arrow in the Types area, to expand the graphical definition of the schema, i.e., the types and elements defined for the Web service. If you expand everything by clicking on the + symbols, you will see the full schema as shown in Figure 6. You can switch between the graphical view in Figure 6 and a source view using the tabs at the lower left of the WSDL Editor.
Figure 6. WSDL Editor showing schema
Return to the graph in Figure 5 by clicking on the left-pointing blue arrow
at the upper left of the editor. Expand the service element in the
services area, then expand the PortType element, the operation and finally
expand the messages. Figure 7 shows a composite of the results of
expansion, after clicking the input for the
getQuote method on the top and clicking
output for the getQuote method on
the bottom. As before, if you click on any item, you will see details in
the lower panes of the editor. You can easily see that the WSDL service
element is named StockFullQuoteService (assigned by the wizard), and it
contains a WSDL port element named StockFullQuote which implements a WSDL
portType also named StockFullQuote.
Figure 7. WSDL Editor showing expanded WSDL service element
In Figure 4, you can also see the wizard has created Web services
deployment descriptor for the server,
webservices.xml and placed it in the
WEB-INF directory, as defined in JSR-109. The
deployment descriptor defines to the Web services environment the various
deployment aspects of Web services for that environment. You can
double-click on webservices.xml
to open it
with the new Web Services Editor. Figure 8 shows the editor viewing
webservices.xml for the Services project. The
tabs at the bottom of the editor let you navigate between the various
aspects of the deployment descriptor. Figure 8 shows the Web Services
view, where you can see the StockFullQuoteService produced by the wizard.
On the right side, you can see references to the WSDL file described above
and a mapping file, discussed below. You can also see a list of the ports,
in this case the single port, StockQuoteFull, defined for
StockFullQuoteService.
Figure 8. Web Services Editor for the Services project - Web Services view
Figure 9 shows the Ports Components view of the deployment descriptor. In
this case, we see the required service endpoint interface and
implementation bean information. In this case, since we've used a Java
bean in the Web container for the service implementation, the latter
contains a servlet link that associates the actual implementation class
defined in web.xml. The following snippet of
web.xml shows how the linkage works to define
the actual implementation of the service as the original
StockFullQuote
JavaBean.
<servlet>
<servlet-name>wstest_StockFullQuote</servlet-name>
<servlet-class>wstest.StockFullQuote</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet> |
For this simple service, no additional information is contained in
webservice.xml.
Figure 9. Web Services Editor for the Services project - Port Components view
JSR-109 requires a mapping deployment descriptor that contains information
to correlate the mapping between the Java interface for the Web service
and WSDL definition of the Web service. As you can see from Figure 4 and
Figure 8, the wizard generates the mapping deployment descriptor, in this
case called StockFullQuote_mapping.xml, and
references it appropriately in webservices.xml.
We will not examine the details, but Figure 10 shows a high level view of
the mapping file using Application Developer's XML Editor.
Figure 10. Mapping Deployment Descriptor
We will use Application Developer's Web Services Explorer to test the
StockFullQuote service. The Web Services Wizard probably already published
the Services project to a WebSphere V5.0.2 test server and started the
server; if that did not happen do so now. Launch the Web Services Explorer
(click the 
icon) and bring up the WSDL page (click on 
icon). In
the Navigator pane, click WSDL Main to bring up the Open WSDL pane. In
that pane, click Browse and you'll see the WSDL Browser dialog. In that
dialog, you can select the Services project and the StockFullQuote.wsdl
file and click Go, then click Go in the Open WSDL pane of the Explorer. In
the Navigator pane of the Explorer, expand the WSDL and components in it
until you see the getQuote operation; click getQuote and you should see
the Action pane appear as shown in Figure 11.
Figure 11. Web Services Explorer Action Pane
Now enter any string in the text input field labeled 'symbol' and click Go. The Status pane (see Figure 12) now shows the response from the Web service with a symbol of "xyz." If you want to see the details of the SOAP request and response, click on the Source link. Figure 13 shows the results. From those results we conclude the Web service has been successfully created and deployed in the Web container, compliant with JSR-109, all with little more than a few clicks.
Figure 12. Web Services Explorer Status Pane
Figure 13. Web Services Explorer Status Pane - Source
We now look at server side support for the EJB container. First create an
EJB project called "EJBServices." Put the EJB project in a different EAR
project than the projects associated with the Web container example; this
minimizes the server restarts needed. Within the EJB project create a
stateless session EJB called "StockFullQuoteEJB" in the package "wstest".
Copy the FullQuote Java class from the Services
project into the wstest package of the
EJBServices project. Add the following as a "business logic" to
StockFullQuoteEJBBean class, and promote the
getQuote method to the remote interface.
Random r = new Random();
public FullQuote getQuote(String symbol) {
int base = r.nextInt(100);
return new FullQuote(symbol, base+2, base+3, base+1);
} |
Now generate the deployment and RMIC code for the EJBServices project. Add the project to the server and start the server if it not already started. You may wish to test the EJB with the Universal Test Client to ensure the EJB is working properly. When you finish, the Navigator view of the EJBServices project looks like Figure 14
Figure 14. EJBServices project
To create a Web service from an EJB, we must first create a Web project will serve as the "router" for Web service requests directed at the EJB. Create a new dynamic Web project called MoreServices and deploy it in the same EAR as the EJBServices projects.
Now we will use the new Web Services Wizard to turn the EJB into a JSR-109 compliant Web service. In the J2EE Hierarchy view, right-click on the StockFullQuoteEJB bean and select New => Other => Web Services => Web Service => Next to start the wizard. In the Web Services panel, you should find the Web service type already selected as EJB Web service, so click Next. In the subsequent Service Deployment Configuration panel shown in Figure 15, ensure that the Router project is set to MoreServices and that the EJB Project is set to EJBServices, then click Next.
Figure 15. Web Services Wizard: Service Deployment Configuration
In the subsequent Web Service EJB Selection panel, shown in Figure 16, you will see the information needed to route requests from the servlet that receives the SOAP/HTTP request to the EJB. All the fields should be correct by default, so click Next.
Figure 16. Web Services Wizard: EJB Selection
The subsequent Web Services Java Bean Identity panel is the same format as for the Web container example above (see Figure 2). Some of the fields contain slightly different information to reflect the differences between the Web contain deployment and EJB contain deployment of Web services; for example, the WSDL files is place in the META-INF directory of the EJB project instead of the WEB-INF directory of the Web project. You should click Finish to let the wizard complete the necessary actions.
Figure 17 shows the EJBService project after the wizard has finished.
Packages without changes are collapsed. In the
wstest package, the wizard produces several
classes like those produced for the Web container example;
FullQuote_Deser,
FullQuote_Helper, and FullQuote_Ser
are identical. Because the "business interface" is identical to the Web
container example, the implementation
StockFullQuoteEJB_SEI is identical to that of
StockFullQuote_SEI above. The Java artifact,
StockFullQuoteEJB_RI fulfills the JSR-109
requirements for a remote interface that exposes both standard EJB methods
and the "business interface" methods.
Figure 17. EJBService project after Web service creation
Figure 17 also shows that the other required artifacts have been generated,
but in this case in the META-INF directory. You
can see the WSDL file, the mapping deployment descriptor file, and the Web
services deployment descriptor,
webservices.xml. Only that latter differs
significantly from those artifacts produced for the Web container, because
it is describing an EJB Web service implementation. As you can see in
Figure 18, the port component implementation details section indicate the
Web service is an EJB.
Figure 18. Port components in webservices.xml for EJBServices
We will use Application Developer's Web Services Explorer to test the
StockFullQuoteEJB service as well. You might need to restart the WebSphere
V5.0.2 test server. Launch the Web Services Explorer if it is not running
and browse to the MoreServices project and the
StockFullQuoteEJB.wsdl file and click
Go, then click Go in the Open WSDL pane. In the Navigator
pane of the Explorer, expand the WSDL and components in it until you see
the getQuote operation; click getQuote and you should see the
Action pane appear as shown in Figure 11. Enter a string in the text entry
field labeled symbol and click Go. You will see a result something
like that shown in Figure 19, indicating successful invocation of the EJB.
The results demonstrate that the Web service has been successfully created
and deployed in the EJB container, compliant with JSR-109, all with little
more than a few clicks.
Figure 19. Web Services Explorer Status Pane
As you can see, Application Developer V5.1 makes it very easy to create, deploy, and test interoperable Web services in a JSR-109 compliant environment like WebSphere V5.0.2. For both Web container and EJB container based Web services, Application Developer can create virtually all of the necessary artifacts. If changes in those artifacts are needed, Application Developer provides specialized editors to greatly simplify the task. Application Developer V5.1 can really accelerate your Web services development for the J2EE environment!
-
Java API for XML-Based RPC (JAX-RPC) [JSR-101]
-
WS-I's Basic Profile V1.0
-
WebSphere Application Server Version 5
Greg Flurry is a Senior Technical Staff Member in IBM's Emerging Technologies group in Austin, Texas. His responsibilities include advancing IBM's e-business technologies. You can contact Greg at flurry@us.ibm.com.
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