com.ericsson.otp.erlang
Class OtpConnection

java.lang.Object
  extended by java.lang.Thread
      extended by com.ericsson.otp.erlang.AbstractConnection
          extended by com.ericsson.otp.erlang.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().


Nested Class Summary
 
Nested classes/interfaces inherited from class java.lang.Thread
java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler
 
Field Summary
protected  GenericQueue queue
           
protected  OtpSelf self
           
 
Fields inherited from class com.ericsson.otp.erlang.AbstractConnection
ChallengeAck, ChallengeReply, ChallengeStatus, connected, cookieOk, ctrlThreshold, defaultLevel, exit2Tag, exit2TTTag, exitTag, exitTTTag, groupLeaderTag, handshakeThreshold, headerLen, linkTag, nodeLinkTag, passThrough, peer, random, regSendTag, regSendTTTag, sendCookie, sendTag, sendThreshold, sendTTTag, socket, traceLevel, unlinkTag, version
 
Fields inherited from class java.lang.Thread
MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY
 
Method Summary
 void deliver(java.lang.Exception e)
          Deliver communication exceptions to the recipient.
 void deliver(OtpMsg msg)
          Deliver messages to the recipient.
 void exit(OtpErlangPid dest, OtpErlangObject reason)
          Send an exit signal to a remote process.
 void link(OtpErlangPid dest)
          Create a link between the local node and the specified process on the remote node.
 int msgCount()
          Return the number of messages currently waiting in the receive queue for this connection.
 OtpPeer peer()
          Get information about the node at the peer end of this connection.
 OtpErlangObject receive()
          Receive a message from a remote process.
 OtpErlangObject receive(long timeout)
          Receive a message from a remote process.
 OtpInputStream receiveBuf()
          Receive a raw (still encoded) message from a remote process.
 OtpInputStream receiveBuf(long timeout)
          Receive a raw (still encoded) message from a remote process.
 OtpMsg receiveMsg()
          Receive a messge complete with sender and recipient information.
 OtpMsg receiveMsg(long timeout)
          Receive a messge complete with sender and recipient information.
 OtpErlangObject receiveRPC()
          Receive an RPC reply from the remote Erlang node.
 OtpSelf self()
          Get information about the node at the local end of this connection.
 void send(OtpErlangPid dest, OtpErlangObject msg)
          Send a message to a process on a remote node.
 void send(java.lang.String dest, OtpErlangObject msg)
          Send a message to a named process on a remote node.
 void sendBuf(OtpErlangPid dest, OtpOutputStream payload)
          Send a pre-encoded message to a process on a remote node.
 void sendBuf(java.lang.String dest, OtpOutputStream payload)
          Send a pre-encoded message to a named process on a remote node.
 void sendRPC(java.lang.String mod, java.lang.String fun, OtpErlangList args)
          Send an RPC request to the remote Erlang node.
 void sendRPC(java.lang.String mod, java.lang.String fun, OtpErlangObject[] args)
          Send an RPC request to the remote Erlang node.
 void unlink(OtpErlangPid dest)
          Remove a link between the local node and the specified process on the remote node.
 
Methods inherited from class com.ericsson.otp.erlang.AbstractConnection
close, do_send, do_send, doAccept, doConnect, finalize, genChallenge, genDigest, getFlags, getTraceLevel, headerType, isConnected, read2BytePackage, readSock, recvChallenge, recvChallengeAck, recvChallengeReply, recvName, recvStatus, run, sendBuf, sendBuf, sendChallenge, sendChallengeAck, sendChallengeReply, sendExit, sendExit2, sendLink, sendName, sendStatus, sendUnlink, setFlags, setTraceLevel
 
Methods inherited from class java.lang.Thread
activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

self

protected OtpSelf self

queue

protected GenericQueue queue
Method Detail

deliver

public void deliver(java.lang.Exception e)
Description copied from class: AbstractConnection
Deliver communication exceptions to the recipient.

Specified by:
deliver in class AbstractConnection

deliver

public void deliver(OtpMsg msg)
Description copied from class: AbstractConnection
Deliver messages to the recipient.

Specified by:
deliver in class AbstractConnection

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.
msg - 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.