Package ch.psi.wica.controlsystem.epics.io

Class EpicsChannelReaderService

java.lang.Object

ch.psi.wica.controlsystem.epics.io.EpicsChannelReaderService

All Implemented Interfaces:

AutoCloseable

@Service
@ThreadSafe
public class EpicsChannelReaderService
extends Object
implements AutoCloseable

A service which offers the possibility to get the metadata or value associated with an EPICS channel.

Implementation Note:

The current implementation uses PSI's CA EPICS client library to obtain a single shared EPICS CA Context per class instance. The EPICS CA context and all associated resources are disposed of when the service instance is closed.

Constructor Summary

Constructors

Constructor	Description
EpicsChannelReaderService(EpicsChannelAccessContextSupplier epicsChannelAccessContextSupplier, EpicsChannelMetadataGetter epicsChannelMetadataGetter, EpicsChannelValueGetter epicsChannelValueGetter)	Returns a new instance that will read and/or write information from EPICS channels of interest using the supplied value getter.

Method Summary

Modifier and Type	Method	Description
void	close()	Disposes of all resources associated with this class instance.
WicaChannelMetadata	readChannelMetadata(EpicsChannelName epicsChannelName, long timeout, TimeUnit timeUnit)	Returns the metadata associated with a channel.
WicaChannelValue	readChannelValue(EpicsChannelName epicsChannelName, long timeout, TimeUnit timeUnit)	Returns the value of a channel.

Methods inherited from class java.lang.Object

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

Constructor Details

EpicsChannelReaderService

public EpicsChannelReaderService(@Autowired
 EpicsChannelAccessContextSupplier epicsChannelAccessContextSupplier,
 @Autowired
 EpicsChannelMetadataGetter epicsChannelMetadataGetter,
 @Autowired
 EpicsChannelValueGetter epicsChannelValueGetter)

Returns a new instance that will read and/or write information from EPICS channels of interest using the supplied value getter.

Parameters:

epicsChannelAccessContextSupplier - an object which can be used to obtain a Channel-Access context.

epicsChannelMetadataGetter - an object that can get and build the returned metadata.

epicsChannelValueGetter - an object that can get and build the returned value.

Method Details

readChannelMetadata

public WicaChannelMetadata readChannelMetadata(EpicsChannelName epicsChannelName,
 long timeout,
 TimeUnit timeUnit)

Returns the metadata associated with a channel.

This method incurs the network cost of establishing a channel to the remote data source and performing a synchronous GET operation.

Parameters:

epicsChannelName - the name of the channel.

timeout - the timeout to be applied when attempting to get the channel metadata from the underlying data source. If a timeout occurs the returned value will be WicaChannelMetadataUnknown.

timeUnit - the time units to be used.

Returns:

the metadata.

readChannelValue

public WicaChannelValue readChannelValue(EpicsChannelName epicsChannelName,
 long timeout,
 TimeUnit timeUnit)

Returns the value of a channel.

This method incurs the network cost of establishing a channel to the remote data source and performing a synchronous GET operation.

Parameters:

epicsChannelName - the name of the channel.

timeout - the timeout to be applied when attempting to get the channel value from the underlying data source. If a timeout occurs the returned value will be WicaChannelValueDisconnected.

timeUnit - the time units to be used.

Returns:

the value.

close

public void close()

Disposes of all resources associated with this class instance.

Specified by:

close in interface AutoCloseable