JESS: Jess as Web Service

[Juan Ondiviela]

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Hello, I'm trying to develop a Web Service under Tomcat and axis using Java. I'm just beginning so I deployed a service with the basic method "executeCommand". I've implemented a client which invokes this method... Until here everything works fine, the problem comes with the response via SOAP. Since the return value is a jess.Value object and it's not directly serializable,  I cannot get the right  answer at the client side (I receive a null object). I would like to know how could I solve this problem, I tried this code:

            Service  service = new Service();
            Call     call    = (Call) service.createCall();
  
            call.setTargetEndpointAddress( new java.net.URL(endpointURL) );
            call.setOperationName(new QName("urn:myJess","executeCommand"));
            call.addParameter( "arg1", XMLType.XSD_STRING, ParameterMode.IN);
            call.setReturnType( org.apache.axis.encoding.XMLType.XSD_ANYTYPE );
            QName qname = new QName( "urn:myJess", "Value" );

            call.registerTypeMapping(Value.class, qname,
            new org.apache.axis.encoding.ser.BeanSerializerFactory(Value.class, qname),
            new org.apache.axis.encoding.ser.BeanDeserializerFactory(Value.class, qname)); 
               
            Value ret = (Value) call.invoke( new Object[] { textToSend } );


and I added this to the wsdd file

          <beanMapping qname="myNS:Value"
                  xmlns:myNS="urn:myJess"
                  languageSpecificType="java:jess.Value"/>
          </service>
I think it doesn't work because jess.Value is not a Bean Class.

Then, I also tried

<typeMapping qname="typeNS:Value" 


      xmlns:typeNS="urn:myJess"
      languageSpecificType="java:"
      serializer="ValueSerFactory"
      deserializer="ValueDeserFactory"
      encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>


  </service>

but since all jess.Value attributes are declared private, I cannot compile the classes which implement serialization/deserialization of jess values.


Thank you very much, I'd be very grateful if could get this problem fixed.

    Juan

[Bob Garvey]

A SOAP implementation that I use achieves a simplification of SOAP
development by having only one method which is exposed and that method
is the same for any application so developed.  The one parameter of that
method is an array of (DOM) Elements and it returns an array of
Elements.  Because an Element can be the top node of a DOM tree any
information is able to be passed in the SOAP message and the
specification of methods is essentially eliminated.

A control element is one of the elements in the Element Array  to
further define the requirements of the call and is generally analogous
to the request which wraps the request parameters.  Another control
element is in the return array in which you can wrap return responses as
converted to strings via DOM which SOAP converts to xml.



Juan Ondiviela said the following on 4/10/2008 6:58 AM:

> Hello, I'm trying to develop a Web Service under Tomcat and axis using
> Java. I'm just beginning so I deployed a service with the basic method
> "executeCommand". I've implemented a client which invokes this
> method... Until here everything works fine, the problem comes with the
> response via SOAP. Since the return value is a jess.Value object and
> it's not directly serializable,  I cannot get the right  answer at the
> client side (I receive a null object). I would like to know how could
> I solve this problem, I tried this code:
>
>             Service  service = new Service();
>             Call     call    = (Call) service.createCall();
>
>             call.setTargetEndpointAddress( new
> java.net.URL(endpointURL) );
>             call.setOperationName(new
> QName("urn:myJess","executeCommand"));
>             call.addParameter( "arg1", XMLType.XSD_STRING,
> ParameterMode.IN);
>             call.setReturnType(
> org.apache.axis.encoding.XMLType.XSD_ANYTYPE );
>             QName qname = new QName( "urn:myJess", "Value" );
>
>             call.registerTypeMapping(Value.class, qname,
>             new
> org.apache.axis.encoding.ser.BeanSerializerFactory(Value.class, qname),
>             new
> org.apache.axis.encoding.ser.BeanDeserializerFactory(Value.class,
> qname));
>
>             Value ret = (Value) call.invoke( new Object[] { textToSend
> } );
>
>
> and I added this to the wsdd file
>
>           <beanMapping qname="myNS:Value"
>                   xmlns:myNS="urn:myJess"
>                   languageSpecificType="java:jess.Value"/>
>           </service>
> I think it doesn't work because jess.Value is not a Bean Class.
>
> Then, I also tried
>
> <typeMapping qname="typeNS:Value"
>
>
>       xmlns:typeNS="urn:myJess"
>       languageSpecificType="java:"
>       serializer="ValueSerFactory"
>       deserializer="ValueDeserFactory"
>       encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
>
>
>   </service>
> but since all jess.Value attributes are declared private, I cannot
> compile the classes which implement serialization/deserialization of
> jess values.
>
>
> Thank you very much, I'd be very grateful if could get this problem fixed.
>
>     Juan

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[Ernest Friedman-Hill]

Hi Juan,

This is why I just don't get the whole "web services" thing. At some  
point, it was intended as a lighter, simpler, portable replacement  
for things like CORBA, DCOM, and RMI, but it's turned into something  
vastly *more* complex, *more* heavyweight, and at least as, if not  
more, vendor-dependent. Struggling mightily to get this "easy to use"  
wrapper-builder to adapt itself to such a simple API should make you  
question the value of the whole process.

Anyway, to make this even more complex for you, Value is a  
polymorphic class; some Jess data types are returned as *subclasses*  
of Value.

In any case, only some types of Value objects (STRING, SYMBOL, FLOAT,  
INTEGER, LONG, maybe FACT_ID as an int) are going to be meaningful at  
the client end in a Web Services context, so if it were me, I'd just  
write a small Java wrapper around executeCommand() (that name is  
deprecated, by the way; use eval() instead) which either just  
returned these simple types as a String or, if you wanted to get  
fancy, returned your own simpler Value-like class which was more  
amenable to marshalling via SOAP.



On Apr 10, 2008, at 7:58 AM, Juan Ondiviela wrote:

> Hello, I'm trying to develop a Web Service under Tomcat and axis  
> using Java. I'm just beginning so I deployed a service with the  
> basic method "executeCommand". I've implemented a client which  
> invokes this method... Until here everything works fine, the  
> problem comes with the response via SOAP. Since the return value is  
> a jess.Value object and it's not directly serializable,  I cannot  
> get the right  answer at the client side (I receive a null object).  
> I would like to know how could I solve this problem, I tried this  
> code:
>
>             Service  service = new Service();
>             Call     call    = (Call) service.createCall();
>
>             call.setTargetEndpointAddress( new java.net.URL
> (endpointURL) );
>             call.setOperationName(new QName
> ("urn:myJess","executeCommand"));
>             call.addParameter( "arg1", XMLType.XSD_STRING,  
> ParameterMode.IN);
>             call.setReturnType
> ( org.apache.axis.encoding.XMLType.XSD_ANYTYPE );
>             QName qname = new QName( "urn:myJess", "Value" );
>
>             call.registerTypeMapping(Value.class, qname,
>             new org.apache.axis.encoding.ser.BeanSerializerFactory
> (Value.class, qname),
>             new org.apache.axis.encoding.ser.BeanDeserializerFactory
> (Value.class, qname));
>
>             Value ret = (Value) call.invoke( new Object[]  
> { textToSend } );
>
>
> and I added this to the wsdd file
>
>           <beanMapping qname="myNS:Value"
>                   xmlns:myNS="urn:myJess"
>                   languageSpecificType="java:jess.Value"/>
>           </service>
> I think it doesn't work because jess.Value is not a Bean Class.
>
> Then, I also tried
>
> <typeMapping qname="typeNS:Value"
>
> xmlns:typeNS="urn:myJess"
> languageSpecificType="java:"
> serializer="ValueSerFactory"
> deserializer="ValueDeserFactory"
> encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
>
> </service>but since all jess.Value attributes are declared private,  
> I cannot compile the classes which implement serialization/
> deserialization of jess values.
>
>
> Thank you very much, I'd be very grateful if could get this problem  
> fixed.
>
>     Juan

---------------------------------------------------------
Ernest Friedman-Hill
Informatics & Decision Sciences          Phone: [phone]
Sandia National Labs                FAX:   [phone]
PO Box 969, MS 9012                 ejfried@...
Livermore, CA 94550                 http://www.jessrules.com




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