Class OtpConnection

  • All Implemented Interfaces:
    java.lang.Runnable

    public class OtpConnection
    extends AbstractConnection
    Maintains a connection between a Java process and a remote Erlang, Java or C node. The object maintains connection state and allows data to be sent to and received from the peer.

    Once a connection is established between the local node and a remote node, the connection object can be used to send and receive messages between the nodes and make rpc calls (assuming that the remote node is a real Erlang node).

    The various receive methods are all blocking and will return only when a valid message has been received or an exception is raised.

    If an exception occurs in any of the methods in this class, the connection will be closed and must be explicitely reopened in order to resume communication with the peer.

    It is not possible to create an instance of this class directly. OtpConnection objects are returned by OtpSelf.connect() and OtpSelf.accept().

    • Method Detail

      • peer

        public OtpPeer peer()
        Get information about the node at the peer end of this connection.
        Returns:
        the Node representing the peer node.
      • self

        public OtpSelf self()
        Get information about the node at the local end of this connection.
        Returns:
        the Node representing the local node.
      • msgCount

        public int msgCount()
        Return the number of messages currently waiting in the receive queue for this connection.
      • receive

        public OtpErlangObject receive()
                                throws java.io.IOException,
                                       OtpErlangExit,
                                       OtpAuthException
        Receive a message from a remote process. This method blocks until a valid message is received or an exception is raised.

        If the remote node sends a message that cannot be decoded properly, the connection is closed and the method throws an exception.

        Returns:
        an object containing a single Erlang term.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
        OtpErlangExit - if an exit signal is received from a process on the peer node.
        OtpAuthException - if the remote node sends a message containing an invalid cookie.
      • receive

        public OtpErlangObject receive​(long timeout)
                                throws java.lang.InterruptedException,
                                       java.io.IOException,
                                       OtpErlangExit,
                                       OtpAuthException
        Receive a message from a remote process. This method blocks at most for the specified time, until a valid message is received or an exception is raised.

        If the remote node sends a message that cannot be decoded properly, the connection is closed and the method throws an exception.

        Parameters:
        timeout - the time in milliseconds that this operation will block. Specify 0 to poll the queue.
        Returns:
        an object containing a single Erlang term.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
        OtpErlangExit - if an exit signal is received from a process on the peer node.
        OtpAuthException - if the remote node sends a message containing an invalid cookie.
        java.lang.InterruptedException - if no message if the method times out before a message becomes available.
      • receiveBuf

        public OtpInputStream receiveBuf()
                                  throws java.io.IOException,
                                         OtpErlangExit,
                                         OtpAuthException
        Receive a raw (still encoded) message from a remote process. This message blocks until a valid message is received or an exception is raised.

        If the remote node sends a message that cannot be decoded properly, the connection is closed and the method throws an exception.

        Returns:
        an object containing a raw (still encoded) Erlang term.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
        OtpErlangExit - if an exit signal is received from a process on the peer node, or if the connection is lost for any reason.
        OtpAuthException - if the remote node sends a message containing an invalid cookie.
      • receiveBuf

        public OtpInputStream receiveBuf​(long timeout)
                                  throws java.lang.InterruptedException,
                                         java.io.IOException,
                                         OtpErlangExit,
                                         OtpAuthException
        Receive a raw (still encoded) message from a remote process. This message blocks at most for the specified time until a valid message is received or an exception is raised.

        If the remote node sends a message that cannot be decoded properly, the connection is closed and the method throws an exception.

        Parameters:
        timeout - the time in milliseconds that this operation will block. Specify 0 to poll the queue.
        Returns:
        an object containing a raw (still encoded) Erlang term.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
        OtpErlangExit - if an exit signal is received from a process on the peer node, or if the connection is lost for any reason.
        OtpAuthException - if the remote node sends a message containing an invalid cookie.
        java.lang.InterruptedException - if no message if the method times out before a message becomes available.
      • receiveMsg

        public OtpMsg receiveMsg()
                          throws java.io.IOException,
                                 OtpErlangExit,
                                 OtpAuthException
        Receive a messge complete with sender and recipient information.
        Returns:
        an OtpMsg containing the header information about the sender and recipient, as well as the actual message contents.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
        OtpErlangExit - if an exit signal is received from a process on the peer node, or if the connection is lost for any reason.
        OtpAuthException - if the remote node sends a message containing an invalid cookie.
      • receiveMsg

        public OtpMsg receiveMsg​(long timeout)
                          throws java.lang.InterruptedException,
                                 java.io.IOException,
                                 OtpErlangExit,
                                 OtpAuthException
        Receive a messge complete with sender and recipient information. This method blocks at most for the specified time.
        Parameters:
        timeout - the time in milliseconds that this operation will block. Specify 0 to poll the queue.
        Returns:
        an OtpMsg containing the header information about the sender and recipient, as well as the actual message contents.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
        OtpErlangExit - if an exit signal is received from a process on the peer node, or if the connection is lost for any reason.
        OtpAuthException - if the remote node sends a message containing an invalid cookie.
        java.lang.InterruptedException - if no message if the method times out before a message becomes available.
      • send

        public void send​(OtpErlangPid dest,
                         OtpErlangObject msg)
                  throws java.io.IOException
        Send a message to a process on a remote node.
        Parameters:
        dest - the Erlang PID of the remote process.
        msg - the message to send.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • send

        public void send​(java.lang.String dest,
                         OtpErlangObject msg)
                  throws java.io.IOException
        Send a message to a named process on a remote node.
        Parameters:
        dest - the name of the remote process.
        msg - the message to send.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • sendBuf

        public void sendBuf​(java.lang.String dest,
                            OtpOutputStream payload)
                     throws java.io.IOException
        Send a pre-encoded message to a named process on a remote node.
        Parameters:
        dest - the name of the remote process.
        payload - the encoded message to send.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • sendBuf

        public void sendBuf​(OtpErlangPid dest,
                            OtpOutputStream payload)
                     throws java.io.IOException
        Send a pre-encoded message to a process on a remote node.
        Parameters:
        dest - the Erlang PID of the remote process.
        payload - the encoded message to send.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • sendRPC

        public void sendRPC​(java.lang.String mod,
                            java.lang.String fun,
                            OtpErlangObject[] args)
                     throws java.io.IOException
        Send an RPC request to the remote Erlang node. This convenience function creates the following message and sends it to 'rex' on the remote node:
         { self, { call, Mod, Fun, Args, user } }
         

        Note that this method has unpredicatble results if the remote node is not an Erlang node.

        Parameters:
        mod - the name of the Erlang module containing the function to be called.
        fun - the name of the function to call.
        args - an array of Erlang terms, to be used as arguments to the function.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • sendRPC

        public void sendRPC​(java.lang.String mod,
                            java.lang.String fun,
                            OtpErlangList args)
                     throws java.io.IOException
        Send an RPC request to the remote Erlang node. This convenience function creates the following message and sends it to 'rex' on the remote node:
         { self, { call, Mod, Fun, Args, user } }
         

        Note that this method has unpredicatble results if the remote node is not an Erlang node.

        Parameters:
        mod - the name of the Erlang module containing the function to be called.
        fun - the name of the function to call.
        args - a list of Erlang terms, to be used as arguments to the function.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • receiveRPC

        public OtpErlangObject receiveRPC()
                                   throws java.io.IOException,
                                          OtpErlangExit,
                                          OtpAuthException
        Receive an RPC reply from the remote Erlang node. This convenience function receives a message from the remote node, and expects it to have the following format:
         { rex, Term }
         
        Returns:
        the second element of the tuple if the received message is a two-tuple, otherwise null. No further error checking is performed.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
        OtpErlangExit - if an exit signal is received from a process on the peer node.
        OtpAuthException - if the remote node sends a message containing an invalid cookie.
      • link

        public void link​(OtpErlangPid dest)
                  throws java.io.IOException
        Create a link between the local node and the specified process on the remote node. If the link is still active when the remote process terminates, an exit signal will be sent to this connection. Use unlink() to remove the link.
        Parameters:
        dest - the Erlang PID of the remote process.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • unlink

        public void unlink​(OtpErlangPid dest)
                    throws java.io.IOException
        Remove a link between the local node and the specified process on the remote node. This method deactivates links created with link().
        Parameters:
        dest - the Erlang PID of the remote process.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.
      • exit

        public void exit​(OtpErlangPid dest,
                         OtpErlangObject reason)
                  throws java.io.IOException
        Send an exit signal to a remote process.
        Parameters:
        dest - the Erlang PID of the remote process.
        reason - an Erlang term describing the exit reason.
        Throws:
        java.io.IOException - if the connection is not active or a communication error occurs.