Examples of org.jgroups.blocks.GroupRequest

org.jgroups.blocks.GroupRequest
Sends a message to all members of the group and waits for all responses (or timeout). Returns a boolean value (success or failure). Results (if any) can be retrieved when done.
The supported transport to send requests is currently either a RequestCorrelator or a generic Transport. One of them has to be given in the constructor. It will then be used to send a request. When a message is received by either one, the receiveResponse() of this class has to be called (this class does not actively receive requests/responses itself). Also, when a view change or suspicion is received, the methods viewChange() or suspect() of this class have to be called.
When started, an array of responses, correlating to the membership, is created. Each response is added to the corresponding field in the array. When all fields have been set, the algorithm terminates. This algorithm can optionally use a suspicion service (failure detector) to detect (and exclude from the membership) fauly members. If no suspicion service is available, timeouts can be used instead (see execute()). When done, a list of suspected members can be retrieved.
Because a channel might deliver requests, and responses to different requests, the GroupRequest class cannot itself receive and process requests/responses from the channel. A mechanism outside this class has to do this; it has to determine what the responses are for the message sent by the execute() method and call receiveResponse() to do so.
Requirements: lossless delivery, e.g. acknowledgment-based message confirmation. @author Bela Ban

        Message msg;
        StateTransferRequest r=new StateTransferRequest(StateTransferRequest.RETURN_STATE, local_addr);
        RspList rsp_list;
        Rsp rsp;
        Address dest;
        GroupRequest req;
        int num_tries=0;




        try {
            msg=new Message(null, null, Util.objectToByteBuffer(r));
        }
        catch(Exception e) {
            if(log.isErrorEnabled()) log.error("exception=" + e);
            return null;
        }


        while(members.size() > 1 && num_tries++ < 3) {  // excluding myself
            dest=target != null? target : determineCoordinator();
            if(dest == null)
                return null;
            msg.setDest(dest);
            dests.removeAllElements();
            dests.addElement(dest);
            req=new GroupRequest(msg, corr, dests, GroupRequest.GET_FIRST, timeout_return_state, 0);
            req.execute();
            rsp_list=req.getResults();
            for(int i=0; i < rsp_list.size(); i++) {  // get the first non-suspected result
                rsp=(Rsp)rsp_list.elementAt(i);
                if(rsp.wasReceived())
                    return (byte[])rsp.getValue();
            }

View Full Code Here

//        return rsp_list.getResults();
//    }




    void sendMakeCopyMessage() throws Throwable {
        GroupRequest req;
        Message msg=new Message();
        StateTransferRequest r=new StateTransferRequest(StateTransferRequest.MAKE_COPY, local_addr);
        Vector dests=new Vector(11);


        for(int i=0; i < members.size(); i++)
             dests.addElement(members.elementAt(i));


        if(dests.size() == 0)
            return;


        try {
            msg.setBuffer(Util.objectToByteBuffer(r));
        }
        catch(Exception e) {
        }


        req=new GroupRequest(msg, corr, dests, GroupRequest.GET_ALL, timeout_return_state, 0);
        req.execute();
    }

View Full Code Here

    void sendGroupRequest() throws Throwable {
        Message msg=new Message();
        RspList lst;
  
        msg.putHeader(HDRNAME, new MyHeader(MyHeader.REQUEST));
        group_req=new GroupRequest(msg,
                                   this, // as Transport
                                   members, // all current members
                                   GroupRequest.GET_ALL);


        group_req.execute();

View Full Code Here

     <em>or</em> timeout time.
     @return RspList A list of responses. Each response is an <code>Object</code> and associated
     to its sender.
     */
    public RspList castMessage(Vector dests, Message msg, int mode, long timeout) {
        GroupRequest _req=null;
        Vector real_dests=dests != null? (Vector)dests.clone() : (Vector)members.clone();


        // This marks message as sent by us ! (used in up()
        // msg.addHeader(new MsgProtHeader(getName()));   ++ already done by RequestCorrelator


        _req=new GroupRequest(msg, _corr, real_dests, mode, timeout, 0);
        try {
            _req.execute();
        }
        catch(Exception e) {
            throw new RuntimeException("failed executing request " + _req, e);
        }


        return _req.getResults();
    }

View Full Code Here

    public Object sendMessage(Message msg, int mode, long timeout) throws TimeoutException, SuspectedException {
        Vector mbrs=new Vector();
        RspList rsp_list=null;
        Object dest=msg.getDest();
        Rsp rsp;
        GroupRequest _req=null;


        if(dest == null) {
            System.out.println("MessageProtocol.sendMessage(): the message's destination is null ! " +
                               "Cannot send message !");
            return null;
        }




        mbrs.addElement(dest);   // dummy membership (of destination address)




        _req=new GroupRequest(msg, _corr, mbrs, mode, timeout, 0);
        try {
            _req.execute();
        }
        catch(Exception e) {
            throw new RuntimeException("failed executing request " + _req, e);
        }


        if(mode == GroupRequest.GET_NONE)
            return null;




        rsp_list=_req.getResults();


        if(rsp_list.size() == 0) {
            if(log.isErrorEnabled()) log.error("response list is empty");
            return null;
        }

View Full Code Here

        Message msg;
        StateTransferRequest r=new StateTransferRequest(StateTransferRequest.RETURN_STATE, local_addr);
        RspList rsp_list;
        Rsp rsp;
        Address dest;
        GroupRequest req;
        int num_tries=0;




        try {
            msg=new Message(null, null, Util.objectToByteBuffer(r));
        }
        catch(Exception e) {
            if(log.isErrorEnabled()) log.error("exception=" + e);
            return null;
        }


        while(members.size() > 1 && num_tries++ < 3) {  // excluding myself
            dest=target != null? target : determineCoordinator();
            if(dest == null)
                return null;
            msg.setDest(dest);
            dests.removeAllElements();
            dests.addElement(dest);
            req=new GroupRequest(msg, corr, dests, GroupRequest.GET_FIRST, timeout_return_state, 0);
            req.execute();
            rsp_list=req.getResults();
            for(int i=0; i < rsp_list.size(); i++) {  // get the first non-suspected result
                rsp=(Rsp)rsp_list.elementAt(i);
                if(rsp.wasReceived())
                    return (byte[])rsp.getValue();
            }

View Full Code Here

//        return rsp_list.getResults();
//    }




    void sendMakeCopyMessage() throws Throwable {
        GroupRequest req;
        Message msg=new Message();
        StateTransferRequest r=new StateTransferRequest(StateTransferRequest.MAKE_COPY, local_addr);
        Vector dests=new Vector(11);


        for(int i=0; i < members.size(); i++)
             dests.addElement(members.elementAt(i));


        if(dests.size() == 0)
            return;


        try {
            msg.setBuffer(Util.objectToByteBuffer(r));
        }
        catch(Exception e) {
        }


        req=new GroupRequest(msg, corr, dests, GroupRequest.GET_ALL, timeout_return_state, 0);
        req.execute();
    }

View Full Code Here

TOP

Related Classes of org.jgroups.blocks.GroupRequest

org.jgroups.Address

org.jgroups.Message

org.jgroups.protocols.relay.SiteAddress

org.jgroups.protocols.STATE_TRANSFER

org.jgroups.stack.MessageProtocol

org.jgroups.tests.GroupRequestPull

org.jgroups.util.Rsp

org.jgroups.util.RspList

java.util.concurrent.TimeoutException

All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.