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Date: Sat, 19 Sep 2009 01:50:51 -0700 (PDT)
From: "Claus Ibsen (JIRA)" <jira@apache.org>
To: camel-dev@activemq.apache.org
Subject: [jira] Updated: (CAMEL-2026) Enable async request-reply by
 enhancing the CamelInvocationHandler so that it is serializable, so that
 camel-spring Proxies can be passed as callback objects
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     [ https://issues.apache.org/activemq/browse/CAMEL-2026?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Claus Ibsen updated CAMEL-2026:
-------------------------------

    Description: 
With minor alteration, the CamelInvocationHandler could be made serializable, and then camel-spring bean proxies could be passed as callback objects in method calls on other camel-spring proxies...enabling async request-reply via spring remoting.

I have achieved this by Wrapping the CamelInvocationHandler, subclassing the CamelProxyFactoryBean, and by attaching a processor to routes that can recieve BeanInvocations that have a callback object.  Integrated into the codebase, this could be much more straightforward, and not require a processor be attached. 

=================CamelInvocationHandlerWrapper
{code}
/**
 * Serializable wrapper for Camel/Spring remoting proxies.
 */
public class CamelInvocationHandlerWrapper implements InvocationHandler, Serializable {


    /*
   Findbugs will complain that inner dosent get set at deserialization time. This is ok.
   You need to have a CamelRemotingProcessor in your inbound camel route that will reset the handler.
    */
    private transient CamelInvocationHandler inner;
    private String serviceUrl;
    private static final long serialVersionUID = 7635312279175935612L;

    /**
     * Create a CamelInvocationHandlerWrapper.
     *
     * @param handler    the handler to use in this VM.
     * @param serviceUrl the serviceUrl to use to rebuild the CamelInvocationHandler if we are serialized and used in a different VM.
     */
    public CamelInvocationHandlerWrapper(CamelInvocationHandler handler, String serviceUrl) {
        this.inner = handler;
        this.serviceUrl = serviceUrl;
    }

    /**
     * {@inheritDoc}
     */
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        if (method.getDeclaringClass().equals(Object.class)) {
            return method.invoke(this, args);
        } else {
            if (inner == null) {
                throw new IllegalStateException("The inner CamelInvocationHandler is null, perhaps there was no CamelRemotingProcessor on your inbound route???");
            } else {
                return inner.invoke(proxy, method, args);
            }
        }

    }

    /**
     * Package Private so the CamelRemotingProcessor can rewire when we are passed remotely.
     *
     * @param context the current camel context.
     * @throws Exception if we cant build an endpoint for the service url or create a producer.
     */
    void rebuildInvocationHandler(CamelContext context) throws Exception {
        Endpoint endpoint = CamelContextHelper.getMandatoryEndpoint(context, serviceUrl);
        Producer producer = endpoint.createProducer();
        producer.start();
        inner = new CamelInvocationHandler(endpoint, producer, new MethodInfoCache(endpoint.getCamelContext()));
    }

    void setServiceUrl(String serviceUrl) {
        this.serviceUrl = serviceUrl;
    }
}
{code}
================Proxy Factory
{code}
/**
 * ProxyFactory that wraps a camel proxy in a serializable form.
 */
public class CamelProxyWrapperFactoryBean extends CamelProxyFactoryBean {


    /**
     * Override the CamelProxyFactoryBean to return a different proxy that uses a CamelInvocationHandlerWrapper.
     *
     * @return a Proxy backed by a CamelInvocationHandlerWrapper for the specified interface.
     * @throws Exception if we cant create the proxy.
     */
    @Override
    public Object getObject() throws Exception {
        Object proxy = super.getObject();
        CamelInvocationHandler handler = (CamelInvocationHandler) Proxy.getInvocationHandler(proxy);
        return Proxy.newProxyInstance(getObjectType().getClassLoader(), new Class[]{getObjectType()}, new CamelInvocationHandlerWrapper(handler, getServiceUrl()));
    }


}
{code}

========processor that "rewires" the transient CamelInvocationHandler by using the service url
{code}
public class CamelRemotingProcessor implements Processor {

    /**
     * Rebuild the CamelInvocationHandler if we were passed a Proxy that has a CamelInvocationHandlerWrapper as its handler.
     *
     * @param invocation the BeanInvocation whose args we check for the Proxy.
     * @param context    the current Camel Context.
     * @throws Exception if something blows up.
     */
    public void rewireProxy(BeanInvocation invocation, CamelContext context) throws Exception {
        Object[] args = invocation.getArgs();
        if (args != null) {
            for (Object arg : args) {
                if (Proxy.isProxyClass(arg.getClass())) {
                    InvocationHandler handler = Proxy.getInvocationHandler(arg);
                    if (handler instanceof CamelInvocationHandlerWrapper) {
                        CamelInvocationHandlerWrapper wrapper = (CamelInvocationHandlerWrapper) handler;
                        wrapper.rebuildInvocationHandler(context);
                    }
                }
            }
        }

    }

    /**
     * {@inheritDoc}
     */
    public void process(Exchange exchange) throws Exception {
        CamelContext context = exchange.getContext();
        BeanInvocation invocation = exchange.getIn().getBody(BeanInvocation.class);
        rewireProxy(invocation, context);
    }
}
{code}


  was:
With minor alteration, the CamelInvocationHandler could be made serializable, and then camel-spring bean proxies could be passed as callback objects in method calls on other camel-spring proxies...enabling async request-reply via spring remoting.

I have achieved this by Wrapping the CamelInvocationHandler, subclassing the CamelProxyFactoryBean, and by attaching a processor to routes that can recieve BeanInvocations that have a callback object.  Integrated into the codebase, this could be much more straightforward, and not require a processor be attached. 

=================CamelInvocationHandlerWrapper
/**
 * Serializable wrapper for Camel/Spring remoting proxies.
 */
public class CamelInvocationHandlerWrapper implements InvocationHandler, Serializable {


    /*
   Findbugs will complain that inner dosent get set at deserialization time. This is ok.
   You need to have a CamelRemotingProcessor in your inbound camel route that will reset the handler.
    */
    private transient CamelInvocationHandler inner;
    private String serviceUrl;
    private static final long serialVersionUID = 7635312279175935612L;

    /**
     * Create a CamelInvocationHandlerWrapper.
     *
     * @param handler    the handler to use in this VM.
     * @param serviceUrl the serviceUrl to use to rebuild the CamelInvocationHandler if we are serialized and used in a different VM.
     */
    public CamelInvocationHandlerWrapper(CamelInvocationHandler handler, String serviceUrl) {
        this.inner = handler;
        this.serviceUrl = serviceUrl;
    }

    /**
     * {@inheritDoc}
     */
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        if (method.getDeclaringClass().equals(Object.class)) {
            return method.invoke(this, args);
        } else {
            if (inner == null) {
                throw new IllegalStateException("The inner CamelInvocationHandler is null, perhaps there was no CamelRemotingProcessor on your inbound route???");
            } else {
                return inner.invoke(proxy, method, args);
            }
        }

    }

    /**
     * Package Private so the CamelRemotingProcessor can rewire when we are passed remotely.
     *
     * @param context the current camel context.
     * @throws Exception if we cant build an endpoint for the service url or create a producer.
     */
    void rebuildInvocationHandler(CamelContext context) throws Exception {
        Endpoint endpoint = CamelContextHelper.getMandatoryEndpoint(context, serviceUrl);
        Producer producer = endpoint.createProducer();
        producer.start();
        inner = new CamelInvocationHandler(endpoint, producer, new MethodInfoCache(endpoint.getCamelContext()));
    }

    void setServiceUrl(String serviceUrl) {
        this.serviceUrl = serviceUrl;
    }
}

================Proxy Factory

/**
 * ProxyFactory that wraps a camel proxy in a serializable form.
 */
public class CamelProxyWrapperFactoryBean extends CamelProxyFactoryBean {


    /**
     * Override the CamelProxyFactoryBean to return a different proxy that uses a CamelInvocationHandlerWrapper.
     *
     * @return a Proxy backed by a CamelInvocationHandlerWrapper for the specified interface.
     * @throws Exception if we cant create the proxy.
     */
    @Override
    public Object getObject() throws Exception {
        Object proxy = super.getObject();
        CamelInvocationHandler handler = (CamelInvocationHandler) Proxy.getInvocationHandler(proxy);
        return Proxy.newProxyInstance(getObjectType().getClassLoader(), new Class[]{getObjectType()}, new CamelInvocationHandlerWrapper(handler, getServiceUrl()));
    }


}

========processor that "rewires" the transient CamelInvocationHandler by using the service url
public class CamelRemotingProcessor implements Processor {

    /**
     * Rebuild the CamelInvocationHandler if we were passed a Proxy that has a CamelInvocationHandlerWrapper as its handler.
     *
     * @param invocation the BeanInvocation whose args we check for the Proxy.
     * @param context    the current Camel Context.
     * @throws Exception if something blows up.
     */
    public void rewireProxy(BeanInvocation invocation, CamelContext context) throws Exception {
        Object[] args = invocation.getArgs();
        if (args != null) {
            for (Object arg : args) {
                if (Proxy.isProxyClass(arg.getClass())) {
                    InvocationHandler handler = Proxy.getInvocationHandler(arg);
                    if (handler instanceof CamelInvocationHandlerWrapper) {
                        CamelInvocationHandlerWrapper wrapper = (CamelInvocationHandlerWrapper) handler;
                        wrapper.rebuildInvocationHandler(context);
                    }
                }
            }
        }

    }

    /**
     * {@inheritDoc}
     */
    public void process(Exchange exchange) throws Exception {
        CamelContext context = exchange.getContext();
        BeanInvocation invocation = exchange.getIn().getBody(BeanInvocation.class);
        rewireProxy(invocation, context);
    }
}


added code snippets

> Enable async request-reply by enhancing the CamelInvocationHandler so that it is serializable, so that camel-spring Proxies can be passed as callback objects
> -------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CAMEL-2026
>                 URL: https://issues.apache.org/activemq/browse/CAMEL-2026
>             Project: Apache Camel
>          Issue Type: Improvement
>          Components: camel-core, camel-spring
>    Affects Versions: 2.0.0
>            Reporter: Scott Clasen
>
> With minor alteration, the CamelInvocationHandler could be made serializable, and then camel-spring bean proxies could be passed as callback objects in method calls on other camel-spring proxies...enabling async request-reply via spring remoting.
> I have achieved this by Wrapping the CamelInvocationHandler, subclassing the CamelProxyFactoryBean, and by attaching a processor to routes that can recieve BeanInvocations that have a callback object.  Integrated into the codebase, this could be much more straightforward, and not require a processor be attached. 
> =================CamelInvocationHandlerWrapper
> {code}
> /**
>  * Serializable wrapper for Camel/Spring remoting proxies.
>  */
> public class CamelInvocationHandlerWrapper implements InvocationHandler, Serializable {
>     /*
>    Findbugs will complain that inner dosent get set at deserialization time. This is ok.
>    You need to have a CamelRemotingProcessor in your inbound camel route that will reset the handler.
>     */
>     private transient CamelInvocationHandler inner;
>     private String serviceUrl;
>     private static final long serialVersionUID = 7635312279175935612L;
>     /**
>      * Create a CamelInvocationHandlerWrapper.
>      *
>      * @param handler    the handler to use in this VM.
>      * @param serviceUrl the serviceUrl to use to rebuild the CamelInvocationHandler if we are serialized and used in a different VM.
>      */
>     public CamelInvocationHandlerWrapper(CamelInvocationHandler handler, String serviceUrl) {
>         this.inner = handler;
>         this.serviceUrl = serviceUrl;
>     }
>     /**
>      * {@inheritDoc}
>      */
>     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
>         if (method.getDeclaringClass().equals(Object.class)) {
>             return method.invoke(this, args);
>         } else {
>             if (inner == null) {
>                 throw new IllegalStateException("The inner CamelInvocationHandler is null, perhaps there was no CamelRemotingProcessor on your inbound route???");
>             } else {
>                 return inner.invoke(proxy, method, args);
>             }
>         }
>     }
>     /**
>      * Package Private so the CamelRemotingProcessor can rewire when we are passed remotely.
>      *
>      * @param context the current camel context.
>      * @throws Exception if we cant build an endpoint for the service url or create a producer.
>      */
>     void rebuildInvocationHandler(CamelContext context) throws Exception {
>         Endpoint endpoint = CamelContextHelper.getMandatoryEndpoint(context, serviceUrl);
>         Producer producer = endpoint.createProducer();
>         producer.start();
>         inner = new CamelInvocationHandler(endpoint, producer, new MethodInfoCache(endpoint.getCamelContext()));
>     }
>     void setServiceUrl(String serviceUrl) {
>         this.serviceUrl = serviceUrl;
>     }
> }
> {code}
> ================Proxy Factory
> {code}
> /**
>  * ProxyFactory that wraps a camel proxy in a serializable form.
>  */
> public class CamelProxyWrapperFactoryBean extends CamelProxyFactoryBean {
>     /**
>      * Override the CamelProxyFactoryBean to return a different proxy that uses a CamelInvocationHandlerWrapper.
>      *
>      * @return a Proxy backed by a CamelInvocationHandlerWrapper for the specified interface.
>      * @throws Exception if we cant create the proxy.
>      */
>     @Override
>     public Object getObject() throws Exception {
>         Object proxy = super.getObject();
>         CamelInvocationHandler handler = (CamelInvocationHandler) Proxy.getInvocationHandler(proxy);
>         return Proxy.newProxyInstance(getObjectType().getClassLoader(), new Class[]{getObjectType()}, new CamelInvocationHandlerWrapper(handler, getServiceUrl()));
>     }
> }
> {code}
> ========processor that "rewires" the transient CamelInvocationHandler by using the service url
> {code}
> public class CamelRemotingProcessor implements Processor {
>     /**
>      * Rebuild the CamelInvocationHandler if we were passed a Proxy that has a CamelInvocationHandlerWrapper as its handler.
>      *
>      * @param invocation the BeanInvocation whose args we check for the Proxy.
>      * @param context    the current Camel Context.
>      * @throws Exception if something blows up.
>      */
>     public void rewireProxy(BeanInvocation invocation, CamelContext context) throws Exception {
>         Object[] args = invocation.getArgs();
>         if (args != null) {
>             for (Object arg : args) {
>                 if (Proxy.isProxyClass(arg.getClass())) {
>                     InvocationHandler handler = Proxy.getInvocationHandler(arg);
>                     if (handler instanceof CamelInvocationHandlerWrapper) {
>                         CamelInvocationHandlerWrapper wrapper = (CamelInvocationHandlerWrapper) handler;
>                         wrapper.rebuildInvocationHandler(context);
>                     }
>                 }
>             }
>         }
>     }
>     /**
>      * {@inheritDoc}
>      */
>     public void process(Exchange exchange) throws Exception {
>         CamelContext context = exchange.getContext();
>         BeanInvocation invocation = exchange.getIn().getBody(BeanInvocation.class);
>         rewireProxy(invocation, context);
>     }
> }
> {code}

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