Package gov.aps.jca

Class Context

java.lang.Object

gov.aps.jca.Context

Direct Known Subclasses:

CAJContext

public abstract class Context
extends Object

The class representing a CA Context. A Context controls all IO operations and the circuits thru which Channels will be created and connected. Since CA 3.14 an application can create more than one context, thus ehancing IO control and Channels managment. Context are created thru the JCALibrary factory class.

See Also:

JCALibrary

Constructor Summary

Constructors

Constructor	Description
Context()

Method Summary

Modifier and Type	Method	Description
abstract void	addContextExceptionListener(ContextExceptionListener l)	Add a ContextExceptionListener to this context.
abstract void	addContextMessageListener(ContextMessageListener l)	Add a ContextMessageListener to this context.
abstract void	attachCurrentThread()	Attach the calling thread to the list of threads allowed to access this context and all its channels.
Channel	createChannel(String name)	Create a new Channel using this context to access a process variable.
Channel	createChannel(String name, short priority)	Create a new Channel using this context to access a process variable.
Channel	createChannel(String name, ConnectionListener l)	Create a new Channel using this context to access a process variable with a ConnectionListener to receive ConnectionEvent from the newly created Channel.
abstract Channel	createChannel(String name, ConnectionListener l, short priority)	Create a new Channel using this context to access a process variable with a ConnectionListener to receive ConnectionEvent from the newly created Channel.
abstract void	destroy()	Clear all ressources attached to this Context
void	dispose()
abstract void	flushIO()	Flush outstanding IO request to the servers.
abstract Channel[]	getChannels()	Get all channels of this context.
abstract ContextExceptionListener[]	getContextExceptionListeners()
abstract ContextMessageListener[]	getContextMessageListeners()
abstract Version	getVersion()
void	initialize()
abstract void	pendEvent(double time)	Process all pending events.
abstract void	pendIO(double timeout)	Process all pending IO operations.
abstract void	poll()	Flush the send buffer and process any outstanding CA background activity.
void	printInfo()	Prints detailed information about the Context to the standard output stream.
void	printInfo(PrintStream out)	Prints detailed information about the Context to the specified output stream.
abstract void	removeContextExceptionListener(ContextExceptionListener l)	Removes a ContextExceptionListener from this context.
abstract void	removeContextMessageListener(ContextMessageListener l)	Removes a ContextMessageListener from this context.
abstract boolean	testIO()	Tests if all synchronous (ie not specifying listeners) get and channel creation requests are completed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Context

public Context()

Method Detail

getVersion

public abstract Version getVersion()

Returns:

version of the context implementation.

initialize

public void initialize()
                throws CAException

Throws:

CAException

getContextMessageListeners

public abstract ContextMessageListener[] getContextMessageListeners()
                                                             throws IllegalStateException

Returns:

an array containing all ContextMessageListeners attached to this context.

Throws:

IllegalStateException - if the context has been destroyed.

addContextMessageListener

public abstract void addContextMessageListener(ContextMessageListener l)
                                        throws CAException,
                                               IllegalStateException

Add a ContextMessageListener to this context.

Parameters:

l - the listener to add

Throws:

IllegalStateException - if the context has been destroyed.

CAException

removeContextMessageListener

public abstract void removeContextMessageListener(ContextMessageListener l)
                                           throws CAException,
                                                  IllegalStateException

Removes a ContextMessageListener from this context.

Parameters:

l - the listener to remove

Throws:

IllegalStateException - if the context has been destroyed.

CAException

getContextExceptionListeners

public abstract ContextExceptionListener[] getContextExceptionListeners()
                                                                 throws IllegalStateException

Returns:

an array containing all ContextExceptionListeners attached to this context.

Throws:

IllegalStateException - if the context has been destroyed.

addContextExceptionListener

public abstract void addContextExceptionListener(ContextExceptionListener l)
                                          throws CAException,
                                                 IllegalStateException

Add a ContextExceptionListener to this context.

Parameters:

l - the listener to add

Throws:

IllegalStateException - if the context has been destroyed.

CAException

removeContextExceptionListener

public abstract void removeContextExceptionListener(ContextExceptionListener l)
                                             throws CAException,
                                                    IllegalStateException

Removes a ContextExceptionListener from this context.

Parameters:

l - the listener to remove

Throws:

IllegalStateException - if the context has been destroyed.

CAException

destroy

public abstract void destroy()
                      throws CAException,
                             IllegalStateException

Clear all ressources attached to this Context

Throws:

IllegalStateException - if the context has been destroyed.

CAException

createChannel

public Channel createChannel(String name)
                      throws CAException,
                             IllegalArgumentException,
                             IllegalStateException

Create a new Channel using this context to access a process variable.

Parameters:

name - the process variable to connect to.

Returns:

the new Channel.

Throws:

CAException - is thrown if a Channel Access error occured while creating the channel.

IllegalArgumentException - is thrown if the channel's name is null or empty.

IllegalStateException - if the context has been destroyed.

createChannel

public Channel createChannel(String name,
                             short priority)
                      throws CAException,
                             IllegalArgumentException,
                             IllegalStateException

Create a new Channel using this context to access a process variable.

Parameters:

name - the process variable to connect to.

priority - channel process priority

Returns:

the new Channel.

Throws:

CAException - is thrown if a Channel Access error occured while creating the channel.

IllegalArgumentException - is thrown if the channel's name is null or empty.

IllegalStateException - if the context has been destroyed.

createChannel

public Channel createChannel(String name,
                             ConnectionListener l)
                      throws CAException,
                             IllegalStateException

Create a new Channel using this context to access a process variable with a ConnectionListener to receive ConnectionEvent from the newly created Channel.

Parameters:

name - the process variable to connect to.

l - the ConnectionListener.

Returns:

the new Channel.

Throws:

CAException - is thrown if a Channel Access error occured while creating the channel.

IllegalStateException - if the context has been destroyed.

createChannel

public abstract Channel createChannel(String name,
                                      ConnectionListener l,
                                      short priority)
                               throws CAException,
                                      IllegalStateException

Create a new Channel using this context to access a process variable with a ConnectionListener to receive ConnectionEvent from the newly created Channel.

Parameters:

name - the process variable to connect to.

l - the ConnectionListener.

priority - channel process priority

Returns:

the new Channel.

Throws:

CAException - is thrown if a Channel Access error occured while creating the channel.

IllegalStateException - if the context has been destroyed.

getChannels

public abstract Channel[] getChannels()

Get all channels of this context.

Returns:

array of channels of this context.

pendIO

public abstract void pendIO(double timeout)
                     throws TimeoutException,
                            CAException,
                            IllegalStateException

Process all pending IO operations.

Parameters:

timeout - the timeout limit.

Throws:

TimeoutException - if all the IO couldn't be processed.

CAException - if a Channel Exception error occured while processing IOs.

IllegalStateException - if the context has been destroyed.

testIO

public abstract boolean testIO()
                        throws CAException,
                               IllegalStateException

Tests if all synchronous (ie not specifying listeners) get and channel creation requests are completed. It will only test request and channel created after the last pendIO() call.

Returns:

true if all pending IO request have been processed. False otherwise.

Throws:

CAException - if a Channel Access error occured while testing IOs

IllegalStateException - if the context has been destroyed.

pendEvent

public abstract void pendEvent(double time)
                        throws CAException,
                               IllegalStateException

Process all pending events.

Parameters:

time - the time during which the Context will process events.

Throws:

CAException - if a Channel Access error occured while pending events

IllegalStateException - if the context has been destroyed.

poll

public abstract void poll()
                   throws CAException,
                          IllegalStateException

Flush the send buffer and process any outstanding CA background activity.

Throws:

CAException - if a Channel Access error occured while testing IOs

IllegalStateException - if the context has been destroyed.

flushIO

public abstract void flushIO()
                      throws CAException,
                             IllegalStateException

Flush outstanding IO request to the servers.

Throws:

CAException - if a Channel Access error occured while flushing IOs

IllegalStateException - if the context has been destroyed.

attachCurrentThread

public abstract void attachCurrentThread()
                                  throws CAException,
                                         IllegalStateException

Attach the calling thread to the list of threads allowed to access this context and all its channels.

Throws:

IllegalStateException - if the context has been destroyed. or if the context doesn't support multiple threads.

CAException

printInfo

public void printInfo()
               throws IllegalStateException

Prints detailed information about the Context to the standard output stream.

Throws:

IllegalStateException - if the context has been destroyed.

printInfo

public void printInfo(PrintStream out)
               throws IllegalStateException

Prints detailed information about the Context to the specified output stream.

Parameters:

out - the output stream.

Throws:

IllegalStateException - if the context has been destroyed.

dispose

public void dispose()