org.epics.pvmanager

Class ChannelHandler

java.lang.Object

org.epics.pvmanager.ChannelHandler

Direct Known Subclasses:

MultiplexedChannelHandler

public abstract class ChannelHandler
extends Object

Manages the connection for each channel of a data source.

Author:

carcassi

Constructor Summary

Constructors

Constructor and Description
ChannelHandler(String channelName) Creates a new channel handler.

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract void	addReader(ChannelHandlerReadSubscription subscription) Used by the data source to add a read request on the channel managed by this handler.
protected abstract void	addWriter(ChannelHandlerWriteSubscription subscription) Used by the data source to prepare the channel managed by this handler for write.
String	getChannelName() Returns the name of the channel.
Map<String,Object>	getProperties() Returns extra information about the channel, typically useful for debugging.
abstract int	getReadUsageCounter() Returns how many readers are open on this channel.
abstract int	getUsageCounter() Returns how many readers or writers are open on this channel.
abstract int	getWriteUsageCounter() Returns how many writers are open on this channel.
abstract boolean	isConnected() Returns true if it is connected.
protected abstract void	removeReader(ChannelHandlerReadSubscription subscription) Used by the data source to remove a read request.
protected abstract void	removeWrite(ChannelHandlerWriteSubscription subscription) Used by the data source to conclude writes to the channel managed by this handler.
protected abstract void	write(Object newValue, ChannelWriteCallback callback) Implements a write operation.

Methods inherited from class java.lang.Object

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

Constructor Detail

ChannelHandler

public ChannelHandler(String channelName)

Creates a new channel handler.

Parameters:

channelName - the name of the channel this handler will be responsible of

Method Detail

getProperties

public Map<String,Object> getProperties()

Returns extra information about the channel, typically useful for debugging.

Returns:

a property map

getChannelName

public String getChannelName()

Returns the name of the channel.

Returns:

the channel name; can't be null

getUsageCounter

public abstract int getUsageCounter()

Returns how many readers or writers are open on this channel.

Returns:

the number of open readers and writers

getReadUsageCounter

public abstract int getReadUsageCounter()

Returns how many readers are open on this channel.

Returns:

the number of open readers

getWriteUsageCounter

public abstract int getWriteUsageCounter()

Returns how many writers are open on this channel.

Returns:

the number of open writers

addReader

protected abstract void addReader(ChannelHandlerReadSubscription subscription)

Used by the data source to add a read request on the channel managed by this handler.

Parameters:

subscription - the data required for a subscription

removeReader

protected abstract void removeReader(ChannelHandlerReadSubscription subscription)

Used by the data source to remove a read request.

Parameters:

subscription - the subscription to remove

addWriter

protected abstract void addWriter(ChannelHandlerWriteSubscription subscription)

Used by the data source to prepare the channel managed by this handler for write.

Parameters:

subscription - the data required for the subscription

removeWrite

protected abstract void removeWrite(ChannelHandlerWriteSubscription subscription)

Used by the data source to conclude writes to the channel managed by this handler.

Parameters:

subscription - the subscription to remove

write

protected abstract void write(Object newValue,
         ChannelWriteCallback callback)

Implements a write operation. Writes the newValues to the channel and call the callback when done.

Parameters:

newValue - new value to be written

callback - called when done or on error

isConnected

public abstract boolean isConnected()

Returns true if it is connected.

Returns:

true if underlying channel is connected