Exposing methods in SEI-based JAX-WS web services

Exposing methods in SEI-based JAX-WS web services

Use the @WebService and @WebMethod annotations on a service endpoint implementation to specify Java methods to expose as Java API for XML-Based Web Services (JAX-WS) web services.

JAX-WS technology enables the implementation of web services based on both the standard service endpoint interface and a Provider interface. When developing a JAX-WS web service starting from existing Java classes, known as the bottom-up approach, we must annotate the class with either the @WebService or @WebServiceProvider annotation to initially define the class as a web service.

Use the Provider interface is the dynamic approach to defining the JAX-WS services. To use the Provider interface, your class must implement the javax.xml.ws.Provider interface, and contain the @WebServiceProvider annotation. The Provider interface has one method, the invoke method, which uses generics in the Java programming language to control both the input and output types when working with various messages or message payloads.

In contrast, we can use Java annotations to describe the web services using the service endpoint interface (SEI) approach.

To initially define a web service, annotate the Java class with the @WebService annotation. We can also selectively annotate individual methods with the @WebMethod annotation to control their exposure as web services operations.

Because of ambiguities across multiple web services specifications regarding how methods are exposed as operations, use the following guidelines to help ensure consistent behavior regardless of the JAX-WS implementation that we use.
To define a basic web service, annotate the implementation class with the @WebService annotation.
To define the web services using an explicit SEI, explicitly reference a Java interface class using the endpointInterface attribute of the @WebService annotation.
Provide a reference to a WSDL file in the wsdlLocation attribute of the @WebService annotation. By specifying a pre-defined WSDL file, performance is improved. Also, discrepancies between the WSDL file and the annotations are reported to you by the runtime environment.
According to the JAX-WS 2.2 specification, if SOAP 1.2 is declared as the binding type and the wsdlLocation attribute is empty string, which is the default, the container cannot generate the WSDL automatically. So if we use ?wsdl to request the WSDL file, the following exception message is displayed:
CWWKW0037E: The WSDL that is compliant with the JAX-WS 2.2 specification cannot be generated.
If we want to display the WSDL file, we must manually generate the WSDL file, put it in the application and specify the wsdlLocation attribute with the correct location.
When we use an explicit SEI, all public methods in the SEI and inherited classes are always exposed. You only need to add @WebMethod annotations to further customize the methods that are already exposed.
Providing a reference in the @WebService annotation to an explicit SEI or to an existing WSDL file helps to remove possible ambiguities when exposing methods.
If we do not use an explicit SEI, follow these rules to ensure that your methods are exposed consistently:

Add an @WebService annotation to your implementation class and all its superclasses that contain methods to expose. Adding an @WebService annotation to a class exposes all public methods in that class that are not static or final.
If we want more granular control to expose only certain methods, use the @WebMethod annotation on selected methods. To ensure that a method is exposed, annotate it with the @WebMethod annotation. If we want to make sure that a method is not exposed, annotate it with the @WebMethod(exclude=true) annotation.
Behavior change for exposing methods that are not annotated:
The behavior of JAX-WS has changed regarding exposing methods as web services operations. This complies with recent clarifications to JAX-WS specifications.

Applications without an explicit SEI or WSDL that are migrated from prior versions might have additional operations exposed as the following shows. We can set a property so the JAX-WS runtime environment uses the legacy behavior. We might need this when migrating applications without a WSDL or an SEI so that additional methods are not exposed.
@WebService
public class Foo {
	@WebMethod
	public void a() {}	// exposed now, exposed before
	public void b() {}	// exposed now, not exposed before
}
Use the new interpretation, public methods in an implementation class and its superclasses are only exposed under the following conditions:

The containing class has an @WebService annotation.
The method does not have an @WebMethod(exclude=true) annotation.

Use the legacy interpretation, a method in an implementation class and its superclasses are only exposed under the following conditions:

The containing class has an @WebService annotation.
The method has no @WebMethod annotations AND no other methods have @WebMethod annotations.
The method has an @WebMethod or @WebMethod(exclude=false) annotation.

To specify that the JAX-WS runtime environment use the legacy @WebMethod behavior, configure the jaxws.runtime.legacyWebMethod=true property. We can configure this property as a Java Virtual achine (JVM) system property or as a property in the META-INF/MANIFEST.MF file of a web application archive (WAR) file. By default, this property is set to false and the application server uses the new behavior.

We might encounter a WSWS7054E error message if all of the following conditions are true:

Your web service application consists of unannotated methods.
The methods are not meant to be mapped to a web service operation.
The application does not reference an SEI nor package a WSDL file.
The error message contains information that is similar to the following text:
javax.xml.ws.WebServiceException: WSWS7054E:
 The Web Services Description Language (WSDL) file could not be generated for the XXXX Web service implementation
 class because of the following error: javax.xml.ws.WebServiceException: Unable to create JAXBContext
The JAX-WS tooling complies with the JAX-WS specification with respect to @WebMethod mapping principles. This change might affect applications that have been dependent on previously non-compliant default behavior. If the applications package and reference WSDL or an SEI and have ALL methods correctly annotated with the @WebMethod exclude flag in the SEI implementation, then this change does not affect you. However, if we are affected, add explicit annotations to your methods to ensure that they are excluded in WSDL generation. For example: @WebMethod(exclude=true) Also, we can package a WSDL with the application to eliminate the need for the run time to generate a WSDL on your behalf.
Behavior change for exposing static and final methods:

Static or final methods in a service without an explicit SEI are no longer exposed as web services operations. To expose them, package the WSDL with the application and set jaxws.runtime.legacyWebMethod=true.

Tasks

Identify the methods to expose as web services operations.
Review the rules for exposing methods as operations on classes annotated with the @WebService annotation.
Use the best practices for applying the @WebMethod and @WebService annotations in applications without SEIs to appropriately expose methods as operations within the web services.

We have used the @WebMethod annotation to specify which methods to expose as web services operations.

If we have upgraded the application server environment and we are experiencing problems, review the following troubleshooting information.
Client errors indicate a mismatch between the WSDL file and portType when using a JAX-WS tooling version 2.1.6 or higher environment
We might receive a client-side error message like the following message:
javax.xml.ws.WebServiceException: The Endpoint validation failed to validate due to the following errors:
:: Invalid Endpoint Interface ::
:: The number of operations in the WSDL portType does not match the number of methods in the SEI or web service
 implementation class.  wsdl operations = [...] dispatch operations = [....]
To correct this problem, we must regenerate client artifacts to match the WSDL file.

Be sure to regenerate the client side artifacts any time we receive an updated WSDL file. bprac
Clients that perform a ?WSDL operation on web services have non-dispatchable operations
After performing a ?WSDL operation, we might receive a WSDL file containing more operations than the JAX-WS runtime environment can dispatch. If the client tries to invoke any of the non-dispatchable operations, the client receives an error like the following message:
The endpoint reference (EPR) for the Operation not found is http://localhost:9086/example/BeanImpl2Service and the WSA 
Action = <WSA_action_from_server>. If this EPR was previously reachable, contact the server administrator.
Clients must only access the operations that the web service intends to expose. We can correct this problem in one of the following ways:

Modify the @WebMethod annotations in the web services application so that the resulting WSDL file exposes the correct set of operations.
Set the jaxws.runtime.legacyWebMethod property to false to ensure that all operations in the WSDL are dispatched.
What to do next

Develop Java artifacts for JAX-WS applications from JavaBeans.

Implement web services applications with JAX-WS
Developing JAX-WS web services with annotations
Generate Java artifacts for JAX-WS applications
JAX-WS annotations
Web services specifications and APIs
Java API for XML Web Services (JAX-WS) API documentation