package org.jgroups.blocks;
import org.jgroups.*;
import org.jgroups.util.*;
import java.lang.reflect.Method;
import java.util.*;
/**
* This class allows a programmer to invoke remote methods in all (or single)
* group members and optionally wait for the return value(s).
* An application will typically create a channel and layer the
* RpcDispatcher building block on top of it, which allows it to
* dispatch remote methods (client role) and at the same time be
* called by other members (server role).
* This class is derived from MessageDispatcher.
* Is the equivalent of RpcProtocol on the application rather than protocol level.
* @author Bela Ban
*/
public class RpcDispatcher extends MessageDispatcher {
protected Object server_obj=null;
/** Marshaller to marshall requests at the caller and unmarshal requests at the receiver(s) */
protected Marshaller req_marshaller=null;
/** Marshaller to marshal responses at the receiver(s) and unmarshal responses at the caller */
protected Marshaller rsp_marshaller=null;
protected MethodLookup method_lookup=null;
public RpcDispatcher() {
}
public RpcDispatcher(Channel channel, MessageListener l, MembershipListener l2, Object server_obj) {
super(channel, l, l2);
this.server_obj=server_obj;
}
public RpcDispatcher(Channel channel, Object server_obj) {
this(channel, null, null, server_obj);
}
public interface Marshaller {
/**
* Marshals the object into a byte[] buffer and returns a Buffer with a ref to the underlying byte[] buffer,
* offset and length.<br/>
* <em>
* Note that the underlying byte[] buffer must not be changed as this would change the buffer of a message which
* potentially can get retransmitted, and such a retransmission would then carry a ref to a changed byte[] buffer !
* </em>
* @param obj
* @return
* @throws Exception
*/
Buffer objectToBuffer(Object obj) throws Exception;
Object objectFromBuffer(byte[] buf, int offset, int length) throws Exception;
}
public static String getName() {return "RpcDispatcher";}
public Marshaller getRequestMarshaller() {return req_marshaller;}
public void setRequestMarshaller(Marshaller m) {
this.req_marshaller=m;
}
public Marshaller getResponseMarshaller() {return rsp_marshaller;}
public void setResponseMarshaller(Marshaller m) {
this.rsp_marshaller=m;
if(corr != null)
corr.setMarshaller(this.rsp_marshaller);
}
public Marshaller getMarshaller() {return req_marshaller;}
public void setMarshaller(Marshaller m) {setRequestMarshaller(m);}
public Object getServerObject() {return server_obj;}
public void setServerObject(Object server_obj) {
this.server_obj=server_obj;
}
public MethodLookup getMethodLookup() {
return method_lookup;
}
public void setMethodLookup(MethodLookup method_lookup) {
this.method_lookup=method_lookup;
}
/**
* Invokes a method in all members and expects responses from members contained in dests (or all members if dests is null).
* @param dests A list of addresses. If null, we'll wait for responses from all cluster members
* @param method_name The name of the target method
* @param args The arguments to be passed
* @param types The types of the arguments
* @param options A collection of call options, e.g. sync versus async, timeout etc
* @return RspList<T> A response list with results, one for each member in dests
* @throws Exception If the sending of the message threw an exception. Note that <em>no</em> exception will be
* thrown if any of the target members threw an exception, but this exception will be in the Rsp
* object for the particular member in the RspList
*/
public <T> RspList<T> callRemoteMethods(Collection<Address> dests, String method_name, Object[] args,
Class[] types, RequestOptions options) throws Exception {
MethodCall method_call=new MethodCall(method_name, args, types);
return callRemoteMethods(dests, method_call, options);
}
/**
* Invokes a method in all members and expects responses from members contained in dests (or all members if dests is null).
* @param dests A list of addresses. If null, we'll wait for responses from all cluster members
* @param method_call The method (plus args) to be invoked
* @param options A collection of call options, e.g. sync versus async, timeout etc
* @return RspList A list of return values and flags (suspected, not received) per member
* @throws Exception If the sending of the message threw an exception. Note that <em>no</em> exception will be
* thrown if any of the target members threw an exception, but this exception will be in the Rsp
* object for the particular member in the RspList
* @since 2.9
*/
public <T> RspList<T> callRemoteMethods(Collection<Address> dests,
MethodCall method_call,
RequestOptions options) throws Exception {
if(dests != null && dests.isEmpty()) { // don't send if dest list is empty
if(log.isTraceEnabled())
log.trace("destination list of " + method_call.getName() + "() is empty: no need to send message");
return new RspList();
}
if(log.isTraceEnabled())
log.trace(new StringBuilder("dests=").append(dests).append(", method_call=").append(method_call).
append(", options=").append(options));
Object buf=req_marshaller != null? req_marshaller.objectToBuffer(method_call) : Util.objectToByteBuffer(method_call);
Message msg=new Message();
if(buf instanceof Buffer)
msg.setBuffer((Buffer)buf);
else
msg.setBuffer((byte[])buf);
if(options != null) {
msg.setFlag(options.getFlags());
if(options.getScope() > 0)
msg.setScope(options.getScope());
}
RspList<T> retval=super.castMessage(dests, msg, options);
if(log.isTraceEnabled()) log.trace("responses: " + retval);
return retval;
}
/**
* Invokes a method in all members and expects responses from members contained in dests (or all members if dests is null).
* @param dests A list of addresses. If null, we'll wait for responses from all cluster members
* @param method_call The method (plus args) to be invoked
* @param options A collection of call options, e.g. sync versus async, timeout etc
* @return NotifyingFuture A future from which the results can be fetched
* @throws Exception If the sending of the message threw an exception. Note that <em>no</em> exception will be
* thrown if any of the target members threw an exception; such an exception will be in the Rsp
* element for the particular member in the RspList
*/
public <T> NotifyingFuture<RspList<T>> callRemoteMethodsWithFuture(Collection<Address> dests,
MethodCall method_call,
RequestOptions options) throws Exception {
if(dests != null && dests.isEmpty()) { // don't send if dest list is empty
if(log.isTraceEnabled())
log.trace(new StringBuilder("destination list of ").append(method_call.getName()).
append("() is empty: no need to send message"));
return new NullFuture<RspList<T>>(new RspList());
}
if(log.isTraceEnabled())
log.trace(new StringBuilder("dests=").append(dests).append(", method_call=").append(method_call).
append(", options=").append(options));
Object buf=req_marshaller != null? req_marshaller.objectToBuffer(method_call) : Util.objectToByteBuffer(method_call);
Message msg=new Message();
if(buf instanceof Buffer)
msg.setBuffer((Buffer)buf);
else
msg.setBuffer((byte[])buf);
if(options != null) {
msg.setFlag(options.getFlags());
if(options.getScope() > 0)
msg.setScope(options.getScope());
}
NotifyingFuture<RspList<T>> retval=super.castMessageWithFuture(dests, msg, options);
if(log.isTraceEnabled()) log.trace("responses: " + retval);
return retval;
}
/**
* Invokes a method in a cluster member and - if blocking - returns the result
* @param dest The target member on which to invoke the method
* @param method_name The name of the method
* @param args The arguments
* @param types The types of the arguments
* @param options The options (e.g. blocking, timeout etc)
* @return The result
* @throws Exception Thrown if the method invocation threw an exception, either at the caller or the callee
*/
public <T> T callRemoteMethod(Address dest, String method_name, Object[] args,
Class[] types, RequestOptions options) throws Exception {
MethodCall method_call=new MethodCall(method_name, args, types);
return (T)callRemoteMethod(dest, method_call, options);
}
/**
* Invokes a method in a cluster member and - if blocking - returns the result
* @param dest The target member on which to invoke the method
* @param call The call to be invoked, including method are arguments
* @param options The options (e.g. blocking, timeout etc)
* @return The result
* @throws Exception Thrown if the method invocation threw an exception, either at the caller or the callee
*/
public <T> T callRemoteMethod(Address dest, MethodCall call, RequestOptions options) throws Exception {
if(log.isTraceEnabled())
log.trace("dest=" + dest + ", method_call=" + call + ", options=" + options);
Object buf=req_marshaller != null? req_marshaller.objectToBuffer(call) : Util.objectToByteBuffer(call);
Message msg=new Message(dest, null, null);
if(buf instanceof Buffer)
msg.setBuffer((Buffer)buf);
else
msg.setBuffer((byte[])buf);
if(options != null) {
msg.setFlag(options.getFlags());
if(options.getScope() > 0)
msg.setScope(options.getScope());
}
T retval=(T)super.sendMessage(msg, options);
if(log.isTraceEnabled()) log.trace("retval: " + retval);
return retval;
}
/**
* Invokes a method in a cluster member and - if blocking - returns the result
* @param dest The target member on which to invoke the method
* @param call The call to be invoked, including method are arguments
* @param options The options (e.g. blocking, timeout etc)
* @return A future from which the result can be fetched. If the callee threw an invocation, an ExecutionException
* will be thrown on calling Future.get().
* @throws Exception Thrown if the method invocation threw an exception
*/
public <T> NotifyingFuture<T> callRemoteMethodWithFuture(Address dest, MethodCall call, RequestOptions options) throws Exception {
if(log.isTraceEnabled())
log.trace("dest=" + dest + ", method_call=" + call + ", options=" + options);
Object buf=req_marshaller != null? req_marshaller.objectToBuffer(call) : Util.objectToByteBuffer(call);
Message msg=new Message(dest, null, null);
if(buf instanceof Buffer)
msg.setBuffer((Buffer)buf);
else
msg.setBuffer((byte[])buf);
if(options != null) {
msg.setFlag(options.getFlags());
if(options.getScope() > 0)
msg.setScope(options.getScope());
}
return super.sendMessageWithFuture(msg, options);
}
protected void correlatorStarted() {
if(corr != null)
corr.setMarshaller(rsp_marshaller);
}
/**
* Message contains MethodCall. Execute it against *this* object and return result.
* Use MethodCall.invoke() to do this. Return result.
*/
@Override
public Object handle(MessageRequest request) throws Exception {
Message req = request.getMessage();
Object body;
MethodCall method_call;
if(server_obj == null) {
if(log.isErrorEnabled()) log.error("no method handler is registered. Discarding request.");
return null;
}
if(req == null || req.getLength() == 0) {
if(log.isErrorEnabled()) log.error("message or message buffer is null");
return null;
}
body=req_marshaller != null?
req_marshaller.objectFromBuffer(req.getBuffer(), req.getOffset(), req.getLength()) : req.getObject();
if(!(body instanceof MethodCall))
throw new IllegalArgumentException("message does not contain a MethodCall object") ;
method_call=(MethodCall)body;
if(log.isTraceEnabled())
log.trace("[sender=" + req.getSrc() + "], method_call: " + method_call);
if(method_call.getMode() == MethodCall.ID) {
if(method_lookup == null)
throw new Exception("MethodCall uses ID=" + method_call.getId() + ", but method_lookup has not been set");
Method m=method_lookup.findMethod(method_call.getId());
if(m == null)
throw new Exception("no method found for " + method_call.getId());
method_call.setMethod(m);
}
return method_call.invoke(server_obj);
}
}