com.ericsson.otp.erlang
Class AbstractConnection

java.lang.Object
  java.lang.Thread
      com.ericsson.otp.erlang.AbstractConnection

All Implemented Interfaces:

java.lang.Runnable

Direct Known Subclasses:

OtpConnection, OtpCookedConnection

public abstract class AbstractConnection
extends java.lang.Thread

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.

This abstract class provides the neccesary methods to maintain the actual connection and encode the messages and headers in the proper format according to the Erlang distribution protocol. Subclasses can use these methods to provide a more or less transparent communication channel as desired.

Note that no receive methods are provided. Subclasses must provide methods for message delivery, and may implement their own receive methods.

If an exception occurs in any of the methods in this class, the connection will be closed and must be reopened in order to resume communication with the peer. This will be indicated to the subclass by passing the exception to its delivery() method.

The System property OtpConnection.trace can be used to change the initial trace level setting for all connections. Normally the initial trace level is 0 and connections are not traced unless setTraceLevel() is used to change the setting for a particular connection. OtpConnection.trace can be used to turn on tracing by default for all connections.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

protected static int	ChallengeAck
protected static int	ChallengeReply
protected static int	ChallengeStatus
protected boolean	connected
protected boolean	cookieOk
protected static int	ctrlThreshold
protected static int	defaultLevel
protected static int	exit2Tag
protected static int	exit2TTTag
protected static int	exitTag
protected static int	exitTTTag
protected static int	groupLeaderTag
protected static int	handshakeThreshold
protected static int	headerLen
protected static int	linkTag
protected static byte	passThrough
protected OtpPeer	peer
protected static java.util.Random	random
protected static int	regSendTag
protected static int	regSendTTTag
protected OtpLocalNode	self
protected boolean	sendCookie
protected static int	sendTag
protected static int	sendThreshold
protected static int	sendTTTag
protected java.net.Socket	socket
protected int	traceLevel
protected static int	unlinkTag
protected static byte	version

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

protected	AbstractConnection(OtpLocalNode self, OtpPeer other) Intiate and open a connection to a remote node.
protected	AbstractConnection(OtpLocalNode self, java.net.Socket s) Accept an incoming connection from a remote node.

Method Summary

void	close() Close the connection to the remote node.
abstract void	deliver(java.lang.Exception e) Deliver communication exceptions to the recipient.
abstract void	deliver(OtpMsg msg) Deliver messages to the recipient.
protected void	do_send(OtpOutputStream header)
protected void	do_send(OtpOutputStream header, OtpOutputStream payload)
protected void	doAccept()
protected void	doConnect(int port)
protected void	finalize()
protected static int	genChallenge()
protected byte[]	genDigest(int challenge, java.lang.String cookie)
int	getFlags()
int	getTraceLevel() Get the trace level for this connection.
protected java.lang.String	headerType(OtpErlangObject h)
boolean	isConnected() Determine if the connection is still alive.
protected byte[]	read2BytePackage()
protected int	readSock(java.net.Socket s, byte[] b)
protected int	recvChallenge()
protected void	recvChallengeAck(int our_challenge)
protected int	recvChallengeReply(int our_challenge)
protected void	recvName(OtpPeer peer)
protected void	recvStatus()
void	run()
protected void	sendBuf(OtpErlangPid from, OtpErlangPid dest, OtpOutputStream payload) Send a pre-encoded message to a process on a remote node.
protected void	sendBuf(OtpErlangPid from, java.lang.String dest, OtpOutputStream payload) Send a pre-encoded message to a named process on a remote node.
protected void	sendChallenge(int dist, int flags, int challenge)
protected void	sendChallengeAck(byte[] digest)
protected void	sendChallengeReply(int challenge, byte[] digest)
protected void	sendExit(OtpErlangPid from, OtpErlangPid dest, OtpErlangObject reason)
protected void	sendExit2(OtpErlangPid from, OtpErlangPid dest, OtpErlangObject reason) Send an exit signal to a remote process.
protected void	sendLink(OtpErlangPid from, OtpErlangPid dest) Create a link between the local node and the specified process on the remote node.
protected void	sendName(int dist, int flags)
protected void	sendStatus(java.lang.String status)
protected void	sendUnlink(OtpErlangPid from, OtpErlangPid dest) Remove a link between the local node and the specified process on the remote node.
void	setFlags(int flags)
int	setTraceLevel(int level) Set the trace level for this connection.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, 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

Field Detail

headerLen

protected static final int headerLen

See Also:

Constant Field Values

passThrough

protected static final byte passThrough

See Also:

Constant Field Values

version

protected static final byte version

See Also:

Constant Field Values

linkTag

protected static final int linkTag

See Also:

Constant Field Values

sendTag

protected static final int sendTag

See Also:

Constant Field Values

exitTag

protected static final int exitTag

See Also:

Constant Field Values

unlinkTag

protected static final int unlinkTag

See Also:

Constant Field Values

regSendTag

protected static final int regSendTag

See Also:

Constant Field Values

groupLeaderTag

protected static final int groupLeaderTag

See Also:

Constant Field Values

exit2Tag

protected static final int exit2Tag

See Also:

Constant Field Values

sendTTTag

protected static final int sendTTTag

See Also:

Constant Field Values

exitTTTag

protected static final int exitTTTag

See Also:

Constant Field Values

regSendTTTag

protected static final int regSendTTTag

See Also:

Constant Field Values

exit2TTTag

protected static final int exit2TTTag

See Also:

Constant Field Values

ChallengeReply

protected static final int ChallengeReply

See Also:

Constant Field Values

ChallengeAck

protected static final int ChallengeAck

See Also:

Constant Field Values

ChallengeStatus

protected static final int ChallengeStatus

See Also:

Constant Field Values

connected

protected boolean connected

socket

protected java.net.Socket socket

peer

protected OtpPeer peer

self

protected OtpLocalNode self

cookieOk

protected boolean cookieOk

sendCookie

protected boolean sendCookie

traceLevel

protected int traceLevel

defaultLevel

protected static int defaultLevel

sendThreshold

protected static int sendThreshold

ctrlThreshold

protected static int ctrlThreshold

handshakeThreshold

protected static int handshakeThreshold

random

protected static java.util.Random random

Constructor Detail

AbstractConnection

protected AbstractConnection(OtpLocalNode self,
                             java.net.Socket s)
                      throws java.io.IOException,
                             OtpAuthException

Accept an incoming connection from a remote node. Used by OtpSelf.accept() to create a connection based on data received when handshaking with the peer node, when the remote node is the connection intitiator.

Throws:

java.io.IOException - if it was not possible to connect to the peer.

OtpAuthException - if handshake resulted in an authentication error

AbstractConnection

protected AbstractConnection(OtpLocalNode self,
                             OtpPeer other)
                      throws java.io.IOException,
                             OtpAuthException

Intiate and open a connection to a remote node.

Throws:

java.io.IOException - if it was not possible to connect to the peer.

OtpAuthException - if handshake resulted in an authentication error.

Method Detail

deliver

public abstract void deliver(java.lang.Exception e)

Deliver communication exceptions to the recipient.

deliver

public abstract void deliver(OtpMsg msg)

Deliver messages to the recipient.

sendBuf

protected void sendBuf(OtpErlangPid from,
                       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

protected void sendBuf(OtpErlangPid from,
                       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.

sendLink

protected void sendLink(OtpErlangPid from,
                        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.

sendUnlink

protected void sendUnlink(OtpErlangPid from,
                          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.

sendExit

protected void sendExit(OtpErlangPid from,
                        OtpErlangPid dest,
                        OtpErlangObject reason)
                 throws java.io.IOException

Throws:

java.io.IOException

sendExit2

protected void sendExit2(OtpErlangPid from,
                         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.

run

public void run()

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

setTraceLevel

public int setTraceLevel(int level)

Set the trace level for this connection. Normally tracing is off by default unless System property OtpConnection.trace was set.

The following levels are valid: 0 turns off tracing completely, 1 shows ordinary send and receive messages, 2 shows control messages such as link and unlink, 3 shows handshaking at connection setup, and 4 shows communication with Epmd. Each level includes the information shown by the lower ones.

Parameters:

level - the level to set.

Returns:

the previous trace level.

getTraceLevel

public int getTraceLevel()

Get the trace level for this connection.

Returns:

the current trace level.

close

public void close()

Close the connection to the remote node.

finalize

protected void finalize()

Overrides:

finalize in class java.lang.Object

isConnected

public boolean isConnected()

Determine if the connection is still alive. Note that this method only reports the status of the connection, and that it is possible that there are unread messages waiting in the receive queue.

Returns:

true if the connection is alive.

do_send

protected void do_send(OtpOutputStream header,
                       OtpOutputStream payload)
                throws java.io.IOException

Throws:

java.io.IOException

do_send

protected void do_send(OtpOutputStream header)
                throws java.io.IOException

Throws:

java.io.IOException

headerType

protected java.lang.String headerType(OtpErlangObject h)

readSock

protected int readSock(java.net.Socket s,
                       byte[] b)
                throws java.io.IOException

Throws:

java.io.IOException

doAccept

protected void doAccept()
                 throws java.io.IOException,
                        OtpAuthException

Throws:

java.io.IOException

OtpAuthException

doConnect

protected void doConnect(int port)
                  throws java.io.IOException,
                         OtpAuthException

Throws:

java.io.IOException

OtpAuthException

genChallenge

protected static int genChallenge()

genDigest

protected byte[] genDigest(int challenge,
                           java.lang.String cookie)

sendName

protected void sendName(int dist,
                        int flags)
                 throws java.io.IOException

Throws:

java.io.IOException

sendChallenge

protected void sendChallenge(int dist,
                             int flags,
                             int challenge)
                      throws java.io.IOException

Throws:

java.io.IOException

read2BytePackage

protected byte[] read2BytePackage()
                           throws java.io.IOException,
                                  OtpErlangDecodeException

Throws:

java.io.IOException

OtpErlangDecodeException

recvName

protected void recvName(OtpPeer peer)
                 throws java.io.IOException

Throws:

java.io.IOException

recvChallenge

protected int recvChallenge()
                     throws java.io.IOException

Throws:

java.io.IOException

sendChallengeReply

protected void sendChallengeReply(int challenge,
                                  byte[] digest)
                           throws java.io.IOException

Throws:

java.io.IOException

recvChallengeReply

protected int recvChallengeReply(int our_challenge)
                          throws java.io.IOException,
                                 OtpAuthException

Throws:

java.io.IOException

OtpAuthException

sendChallengeAck

protected void sendChallengeAck(byte[] digest)
                         throws java.io.IOException

Throws:

java.io.IOException

recvChallengeAck

protected void recvChallengeAck(int our_challenge)
                         throws java.io.IOException,
                                OtpAuthException

Throws:

java.io.IOException

OtpAuthException

sendStatus

protected void sendStatus(java.lang.String status)
                   throws java.io.IOException

Throws:

java.io.IOException

recvStatus

protected void recvStatus()
                   throws java.io.IOException

Throws:

java.io.IOException

setFlags

public void setFlags(int flags)

getFlags

public int getFlags()