Webservice and remote ejbs

[Bob Randall]

I have a requirement to call a remote ejb y in a different ear through ejb x in another ear using webservices on weblogic.

I have some of the steps for using ejb y as a remote service

create the stateless bean y remote interface, bean, home

For exposing the bean y as Web service endpoint interface

Do I need an entry <service-endpoint></service-endpoint> in ejb-jar.xml.

Use weblogic servicegen ant task to generate web-services.xml and put it in ear file specify ejb jar serviceName serviceURI targetNamespace

The webservices.xml looks like

<weblogic-webservices xmlns="http://www.bea.com/ns/weblogic/90">
<webservice-description>
<webservice-description-name>yService</webservice-description-name>
<port-component>
<port-component-name>yServicePort</port-component-name>
<service-endpoint-address>
<webservice-contextpath>/yService</webservice-contextpath>
<webservice-serviceuri>/yService</webservice-serviceuri>
</service-endpoint-address>
</port-component>
</webservice-description>
</weblogic-webservices>

My question is that from x bean can I use JAX-RPC to access y bean and if yes can I have some code sample.

[Peer Reynders]

Originally posted by Bob Randall:
Do I need an entry <service-endpoint></service-endpoint> in ejb-jar.xml.

y -> service provider

x -> service consumer

You will need a <service-endpoint> entry in the service provider ejb-jar.xml. The interface specified there must match the one listed in the webservices.xml <service-endpoint-interface> entry.

The webservices.xml <port-component> entry is also supposed to contain a <service-endpoint-interface> entry which specifies the same interface listed in the <service-endpoint> entry in the ejb-jar.xml. Furthermore you need an <service-impl-bean> entry which contains an <ejb-link> to the implementing ejb.

(service provider) webservices.xml excerpt

  <port-component> <!-- EJB service endpoint interface to wsdl-port mapping -->
    <port-component-name>BookQuoteEJB</port-component-name>
    <wsdl-port>mh:BookQuotePort</wsdl-port>
 
    <!-- For EJB service endpoint this must match the service-endpoint in the ejb-jar.xml -->
    <service-endpoint-interface>com.jwsbook.jaxrpc.BookQuote</service-endpoint-interface>
 
    <!-- bean implementing this interface is specified in ejb-jar.xml ejb-class -->
    <service-impl-bean>
      <!-- ejb-name from the ejb-jar.xml must reside in this JAR -->
      <ejb-link>BookQuoteEJB<ejb-link>
    </service-impl-bean>
    <handler>
      ...
    </handler>
  </port-component>

(service provider) ejb-jar.xml excerpt

  <session>
    ...
    <!-- Name for the EJB service endpoint to be used in the webservices.xml -->
    <ejb-name>BookQuoteEJB</ejb-name>
 
    <!-- service endpoint interface the bean is implementing -->
    <!-- MUST match service-endpoint-interface specified in web-services.xml -->
    <service-endpoint>com.jwsbook.jaxrpc.BookQuote</service-endpoint> 
 
    <!-- Bean �implementing� the service-endpoint -->
    <!-- interface - not in the Java sense, more in the EJB sense -->
    <ejb-class>com.jwsbook.jaxrpc.BookQuoteBean</ejb-class>
 
    <!-- EJB service endpoint MUST be Stateless -->
    <session-type>Stateless</session-type>
    ...
  </session>

(service consumer) ejb-jar.xml excerpt

  <entity>
    ...    
    <!-- HypotheticalEJB accesses BookQuoteEJB endpoint -->
    <!-- requiring a service-ref -->
    <ejb-name>HypotheticalEJB</ejb-name>
    ...
    <!-- Web service used by HypotheticalEJB -->
    <service-ref>
      ...
      <!-- Required JNDI lookup name -->
      <service-ref-name>service/BookQuoteService</service-ref-name> 
 
      <!-- Required interface to be returned by JNDI  -->
      <!-- for Dynamic Proxy, DII use javax.xml.rpc.Service  -->
      <service-interface>com.jwsbook.jaxrpc.BookQuoteService</service-interface>
 
      <!-- must be in JAR (WAR)  -->
      <wsdl-file>META-INF/wsdl/BookQuote.wsdl</wsdl-file>
      <jaxrpc-mapping-file>META-INF/mapping.xml</jaxrpc-mapping-file>
 
      <!-- WSDL service name (fully qualified) -->
      <service-qname>mh:BookQuoteService</service-qname>
 
      <!-- Only used if Service.getPort() is used -->
      <!-- Dynamic Proxy: one for each endpoint interface of the service used -->
      <port-component-ref>
        <service-endpoint-interface>com.jwsbook.jaxrpc.BookQuote</service-endpoint-interface>
 
        <!-- only when endpoint resides in the same EAR, in different JAR -->
        <!-- use qualified path relative to the archive file location -->
        <port-component-link>../ejb/BookQuote.jar#BookQuoteJSE</port-component-link> 
      </port-component-ref>
 
      <!-- Client-side handler -->
      <handler>
        ...
      </handler>
    </service-ref> 
    ...
  </entity>

Originally posted by Bob Randall:
My question is that from x bean can I use JAX-RPC to access y bean

Yes - however I suspect not in the manner that you are hoping. The J2EE 1.4 specification only guarantees that you can expose an SLSB as a web service and it guarantees that an EJB can access a web service. It does not guarantee that the EJB security and transaction semantics are maintained when an EJB accesses another EJB over a web services interface.

J2EE 1.4 does not provide for the propagation of EJB security and transactions over a web services connection.

Theoretically a vendor extension could propagate transactions through the use of WS-T ((Web services transactions)) and security information in SOAP headers or the HTTP session. In most cases however the service provider EJB simply manages its own transactions and its methods are simply exposed with <unchecked/>. It is possible to write your own JAX-RPC server and client side handlers so that you can perform your own client authentication before letting the call go through.

From the perspective of the service consumer EJB calling an EJB-based endpoint is no different than calling a servlet-based endpoint.