org.transitime.ipc.rmi

Class RmiCallInvocationHandler

java.lang.Object

org.transitime.ipc.rmi.RmiCallInvocationHandler

All Implemented Interfaces:

java.lang.reflect.InvocationHandler

public class RmiCallInvocationHandler
extends java.lang.Object
implements java.lang.reflect.InvocationHandler

This code is called on the client side when RMI object is accessed. The RMI stub methods could be called directly but then one would have no control over the invocation. This is a great use of a proxy object with a custom InvocationHandler. We proxy the RMI stub and then when any of the remote methods are called this class' invocation handler adds logging, timing, and handles exceptions. This way we can make sure that a call will work properly even if the server or the registry is restarted or if there is some kind of temporary network problem.

Author:

SkiBu Smith

Constructor Summary

Constructors

Constructor and Description
RmiCallInvocationHandler(java.lang.Object delegate, RmiStubInfo info) Simple constructor.

Method Summary

Modifier and Type	Method and Description
static java.util.Set<java.lang.String>	getAgencies() Returns which agencies have processed RMI calls for.
static int	getCount(java.lang.String agencyId) For specified agency returns how many outstanding RMI calls are currently being processed by the agency server.
static int	getMaxConcurrentCallsPerProject()
static long	getTotalCount(java.lang.String agencyId) Total number of RMI requests sent by this web server to a particular agency server.
java.lang.Object	invoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) The invoke() method does all the work.
static void	setMaxConcurrentCallsPerProject(int maxConcurrentCalls) For if need to change max concurrent calls per project

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RmiCallInvocationHandler

public RmiCallInvocationHandler(java.lang.Object delegate,
                                RmiStubInfo info)

Simple constructor.

Parameters:

delegate -

info -

Method Detail

getMaxConcurrentCallsPerProject

public static int getMaxConcurrentCallsPerProject()

Returns:

current setting of max concurrent calls per project

setMaxConcurrentCallsPerProject

public static void setMaxConcurrentCallsPerProject(int maxConcurrentCalls)

For if need to change max concurrent calls per project

Parameters:

maxConcurrentCalls - New value for max concurrent calls per project

getAgencies

public static java.util.Set<java.lang.String> getAgencies()

Returns which agencies have processed RMI calls for.

Returns:

Enumeration of agency IDs

getCount

public static int getCount(java.lang.String agencyId)

For specified agency returns how many outstanding RMI calls are currently being processed by the agency server.

Parameters:

agencyId -

Returns:

getTotalCount

public static long getTotalCount(java.lang.String agencyId)

Total number of RMI requests sent by this web server to a particular agency server.

Parameters:

agencyId -

Returns:

invoke

public java.lang.Object invoke(java.lang.Object proxy,
                               java.lang.reflect.Method method,
                               java.lang.Object[] args)
                        throws java.lang.Throwable

The invoke() method does all the work. It calls the remote method but it also logs debug info such as how long the call took. Also handles exceptions. If there is an RMI RemoteException then will automatically try to rebind and then try again. This allows RMI to work even if there is a temporary problem like the RMI registry changing. If it is an exception thrown by the server object then that exception is propagated to the client. Also controls how many simultaneous RMI calls there are from this client to a project. If there are too many calls already happening then an exception will be thrown. This prevents a client such as a web server from opening up too many connections when the project gets bogged down.

Specified by:

invoke in interface java.lang.reflect.InvocationHandler

Throws:

java.lang.Throwable