[#BLZ-246] Transparent services invokation with java dynamic proxies

BlazeDS

Transparent services invokation with java dynamic proxies

Created: 09/26/08 12:28 PM Updated: 05/12/09 06:21 PM

Component/s:

Java AMF Client

Security Level:

Public (All JIRA Users )

File Attachments:

AMFClientFactory.java (2 kb)
2.

AMFClientProxy.java (2 kb)
3.

AMFClientProxy.java (2 kb)

Description

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Here are two simple classes to invoke existing services in a transparent manner thanks to java dynamic proxies.

This way you can call your services exactly the same way that if you were not using amf serialization (i.e same classloaders). It is the same thing that apache cxf simple frontend (http://cwiki.apache.org/CXF20DOC/simple-frontend.html) , but for Amf !

Here is a simple example of usage :

AMFClientFactory factory = new AMFClientFactory();
factory.setServiceName("contractService");
factory.setServiceClass(ContractService.class);
factory.setUrl("http://localhost:8081/xxxxx/messagebroker/amf");
ContractService service = (ContractService) factory.create();

List<Contract> contracts = service.findContractType();

If you use spring, the first part can be done by using a spring factory bean. It also supports basic authentication.

It opens a new connection on each method invokation, but it can easily be changed if it is not the best way to do it...

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Rémi Flament - [09/26/08 01:16 PM - edited ]

Here is a example of spring usage :

Spring configuration for AMF remote invokation :

<bean id="contractServiceFactory" class="AMFClientFactory">
<property name="serviceClass" value="xxxxx.xxxx.contract.api.ContractService" />
<property name="url" value="http://localhost:8081/xxxxx/messagebroker/amf" />
<property name="username" value="admin" />
<property name="password" value="admin" />
<property name="serviceName" value="contractService" />
</bean>

<bean id="contractService" class="xxxxx.xxxx.contract.api.ContractService" factory-bean="contractServiceFactory" factory-method="create"/>

Spring configuration local invokation :

        <bean id="contractService" class="xxxxx.xxxx.contract.impl.ContractServiceImpl" />

Java code :

        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext-client.xml");

        ContractService service = (ContractService) context.getBean("contractService");

        List<Contract> contracts = service.findContractType();

As you can see, the java code doesn't change at all when you switch from local invokation to amf remote invokation.

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Rémi Flament - [10/02/08 03:14 AM ]

Here is a fix for BLZ-248 : it checks the return type expected by the developper and it transforms the return double in an int if needed.

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Sebastien Guimont - [02/15/09 03:11 PM ]

When I try to code, I got a ClassCast exception related to object array as result of amfconnection.call that was other than Object[].

here's the correction I made in the AMFClientProxy.java file

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

AMFConnection connection = new AMFConnection();

if (username != null) {
String userpasswd = username + ":" + password;
String encoding = new String(new Base64().encode(userpasswd.getBytes()));
connection.addHttpRequestHeader("Authorization", "Basic " + encoding);
}

connection.connect(url);

Object[] params = args;
if (null == params) {
params = new Object[0];
}

Object callResult = connection.call(serviceName + "." + method.getName(), params);

connection.close();

// Creates a new array with the valid type from the call result
if (method.getReturnType().isArray()) {
Object[] arrayOfValidType = (Object[]) Array.newInstance(method.getReturnType().getComponentType(), ((Object[]) callResult).length);
System.arraycopy(callResult, 0, arrayOfValidType, 0, ((Object[]) callResult).length);
callResult = arrayOfValidType;
}

return callResult;
}

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MS - [02/20/09 05:24 AM ]

This is very helpful - thanks!

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jvroom - [02/24/09 03:18 PM ]

Mete can you take a look at this approach? Is it something that can be layered on top of our existing product or do we need to make product changes to enable this use case?