com.cosylab.epics.caj.cas.util

Class DefaultServerImpl

java.lang.Object

com.cosylab.epics.caj.cas.util.DefaultServerImpl

All Implemented Interfaces:

Server

public class DefaultServerImpl
extends Object
implements Server

Default server implementation. Implementation keeps a hash-map of all registered PVs. When processVariableExistanceTest is called existance test is made on the hash-map. processVariableAttach metod simply retrieves PV from the hash-map.

Field Summary

Fields

Modifier and Type	Field and Description
protected Map	pvs Map of PVs.

Constructor Summary

Constructors

Constructor and Description
DefaultServerImpl()

Method Summary

Modifier and Type	Method and Description
MemoryProcessVariable	createMemoryProcessVariable(String name, DBRType type, Object initialValue) Convenience method to create and register new in-memory process variables.
ProcessVariable	processVariableAttach(String aliasName, ProcessVariableEventCallback eventCallback, ProcessVariableAttachCallback asyncCompletionCallback) This function is called every time that a client attaches to the PV.
ProcessVariableExistanceCompletion	processVariableExistanceTest(String aliasName, InetSocketAddress clientAddress, ProcessVariableExistanceCallback asyncCompletionCallback) This function is called by the server library when it needs to determine if a named process variable (PV) exists (or could be created) in the server tool.
void	registerProcessVaribale(ProcessVariable pv) Register process variable.
void	registerProcessVaribale(String aliasName, ProcessVariable pv) Register process variable.
ProcessVariable	unregisterProcessVaribale(String aliasName) Unregister process variable.

Methods inherited from class java.lang.Object

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

Field Detail

pvs

protected Map pvs

Map of PVs.

Constructor Detail

DefaultServerImpl

public DefaultServerImpl()

Method Detail

createMemoryProcessVariable

public MemoryProcessVariable createMemoryProcessVariable(String name,
                                                         DBRType type,
                                                         Object initialValue)

Convenience method to create and register new in-memory process variables.

Parameters:

name - process variable name.

type - process variable native type.

initialValue - process variable initial value (array expected).

Returns:

created and registered process variable.

registerProcessVaribale

public void registerProcessVaribale(String aliasName,
                                    ProcessVariable pv)

Register process variable. Note: if process variable with aliasName is already registered this will override it.

Parameters:

aliasName - process variable name.

pv - process variable instance.

registerProcessVaribale

public void registerProcessVaribale(ProcessVariable pv)

Register process variable. Note: if process variable with the same name is already registered this will override it.

Parameters:

pv - process variable instance.

unregisterProcessVaribale

public ProcessVariable unregisterProcessVaribale(String aliasName)

Unregister process variable.

Parameters:

aliasName - process variable name

Returns:

unregistered process variable, null if non unregistered.

processVariableAttach

public ProcessVariable processVariableAttach(String aliasName,
                                             ProcessVariableEventCallback eventCallback,
                                             ProcessVariableAttachCallback asyncCompletionCallback)
                                      throws CAStatusException,
                                             IllegalArgumentException,
                                             IllegalStateException

Description copied from interface: Server

This function is called every time that a client attaches to the PV. The name supplied here will be either a canonical PV name or an alias PV name. The request is allowed to complete asynchronously. It is a responsibility of the server tool to detect attempts by the server library to attach to an existing PV. If the PV does not exist then the server tool should create it. Otherwise, the server tool typically will return a pointer to the preexisting PV. The server tool is encouraged to accept multiple PV name aliases for the same PV here. In most situations the server tool should avoid PV duplication by returning a pointer to an existing PV if the PV alias name matches a preexisting PV's name or any of its aliases. In certain specialized rare situations the server tool may choose to create client private process variables that are not shared between clients. In this situation there might be several process variables with the same name. One for each client. For example, a server tool might be written that provides access to archival storage of the historic values of a set of process variables. Each client would specify its date of interest by writing into a client private process variable. Next the client would determine the current value of its subset of named process variables at its privately specified date by attaching to additional client private process variables.

Specified by:

processVariableAttach in interface Server

Parameters:

aliasName - the process variable alias name.

eventCallback - the process variable event callback (where PV reports value changes if interest is true).

asyncCompletionCallback - if asynchronous completion is required method should return null and call ProcessVariableExistanceCompletionCallback.processVariableAttachCompleted() method.

Returns:

requested ProcessVariable instance, null if operation is to be done asynchronously or exception is thrown in case of an error (non-existant PV, etc.).

Throws:

CAStatusException - 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.

See Also:

Server.processVariableAttach(java.lang.String, gov.aps.jca.cas.ProcessVariableEventCallback, gov.aps.jca.cas.ProcessVariableAttachCallback)

processVariableExistanceTest

public ProcessVariableExistanceCompletion processVariableExistanceTest(String aliasName,
                                                                       InetSocketAddress clientAddress,
                                                                       ProcessVariableExistanceCallback asyncCompletionCallback)
                                                                throws CAException,
                                                                       IllegalArgumentException,
                                                                       IllegalStateException

Description copied from interface: Server

This function is called by the server library when it needs to determine if a named process variable (PV) exists (or could be created) in the server tool. The request is allowed to complete asynchronously. The server tool is encouraged to accept multiple PV name aliases for the same PV here. NOTE: return ProcessVariableExistanceCompletion.DOES_NOT_EXIST_HERE if too many simultaneous asynchronous operations are pending against the server. The client library will retry the request at some time in the future.

Specified by:

processVariableExistanceTest in interface Server

Parameters:

aliasName - the process variable alias name.

clientAddress - the client which requested test.

asyncCompletionCallback - if asynchronous completion is required method should return ProcessVariableExistanceCompletion.ASYNC_COMPLETION and call ProcessVariableExistanceCompletionCallback.processVariableExistanceTestCompleted() method.

Returns:

process variable existance status.

Throws:

IllegalArgumentException - is thrown if the process variable name is invalid.

IllegalStateException - if the context has been destroyed.

CAException

See Also:

Server.processVariableExistanceTest(java.lang.String, java.net.InetSocketAddress, gov.aps.jca.cas.ProcessVariableExistanceCallback)