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 necessary 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

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Method Summary

Modifier and Type	Method and Description
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.
int	getFlags()
int	getTraceLevel() Get the trace level for this connection.
boolean	isConnected() Determine if the connection is still alive.
void	run()
void	setFlags(int flags)
int	setTraceLevel(int level) Set the trace level for this connection.

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

close

public void close()

Close the connection to the remote node.

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.

getFlags

public int getFlags()

getTraceLevel

public int getTraceLevel()

Get the trace level for this connection.

Returns:

the current trace level.

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.

run

public void run()

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

setFlags

public void setFlags(int flags)

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.