Java WebServices with Axis

[Krishnan Raman]

Hi There,

I am using Axis 1.2 to implement Java web services. I have put a simple sample and it works with primitive data types in JBOSS.

Now I want to return a collection like ArrayList from a Web Service. When I try this, it shows me the following error.

{http://xml.apache.org/axis/}stackTrace:java.io.IOException: java.lang.IllegalArgumentException: object is not an instance of declaring class
at org.apache.axis.encoding.ser.BeanSerializer.serialize(BeanSerializer.java:275)
at org.apache.axis.encoding.SerializationContext.serializeActual(SerializationContext.java:1504)
at org.apache.axis.encoding.SerializationContext.serialize(SerializationContext.java:980)
at org.apache.axis.encoding.SerializationContext.serialize(SerializationContext.java:734)
at org.apache.axis.encoding.ser.ArraySerializer.serialize(ArraySerializer.java:425)
at org.apache.axis.encoding.SerializationContext.serializeActual(SerializationContext.java:1504)
at org.apache.axis.encoding.SerializationContext.serialize(SerializationContext.java:980)
at org.apache.axis.encoding.SerializationContext.serialize(SerializationContext.java:801)
at org.apache.axis.message.RPCParam.serialize(RPCParam.java:208)
at org.apache.axis.message.RPCElement.outputImpl(RPCElement.java:433)
at org.apache.axis.message.MessageElement.output(MessageElement.java:1208)
at org.apache.axis.message.SOAPBody.outputImpl(SOAPBody.java:139)
at org.apache.axis.message.SOAPEnvelope.outputImpl(SOAPEnvelope.java:478)
at org.apache.axis.message.MessageElement.output(MessageElement.java:1208)
at org.apache.axis.SOAPPart.writeTo(SOAPPart.java:315)
at org.apache.axis.SOAPPart.writeTo(SOAPPart.java:269)
at org.apache.axis.Message.writeTo(Message.java:539)
at org.apache.axis.transport.http.AxisServlet.sendResponse(AxisServlet.java:902)
at org.apache.axis.transport.http.AxisServlet.doPost(AxisServlet.java:777)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at org.apache.axis.transport.http.AxisServletBase.service(AxisServletBase.java:327)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
at java.lang.Thread.run(Thread.java:619)


Can anyone provide a sample on how to return a collection from a Web Service after serializing it.

Thanks
Krishnan

[William Brogden]

The answer is simple - NEVER try to return a collection, instead return an array. All collections have simple and fast methods to turn the contents into an array.

Think about it - does the client really need the functionality of a collection? Almost certainly not, and if they do there are always simple array to collection constructors.

Another point - what would a non-Java client do with a collection if you could get it serialized?

Bill

[Peer Reynders]

See also
Axis2 support for collections
Implementing Collections In WebServices