com.ericsson.otp.erlang

Class OtpConnection

java.lang.Object

java.lang.Thread

com.ericsson.otp.erlang.AbstractConnection

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

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Method Summary

Modifier and Type	Method and Description
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, getFlags, getTraceLevel, isConnected, run, 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

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

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

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.

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.

msgCount

public int msgCount()

Return the number of messages currently waiting in the receive queue for this connection.

peer

public OtpPeer peer()

Get information about the node at the peer end of this connection.

Returns:

the Node representing the peer node.

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.

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.

self

public OtpSelf self()

Get information about the node at the local end of this connection.

Returns:

the Node representing the local node.

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(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.

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.

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.

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.

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.