Package com.singularsys.jep.misc.publishingvariable

Class VariableTableSubscriber

java.lang.Object

com.singularsys.jep.misc.publishingvariable.VariableTableSubscriber

All Implemented Interfaces:

Flow.Subscriber<VariableTableAction>

Direct Known Subclasses:

PublishingVariableTest.MyVariableTableSubscriber, VariableTableUpdater

public class VariableTableSubscriber
extends Object
implements Flow.Subscriber<VariableTableAction>

Convenience class for implementing a Subscriber of VariableTableActions. Depending on the action the appropriate method, like variableAdded(String, Object), is called. This class is intended to be extended by the user to provide the desired functionality. The default implementation of each method does nothing.

An example implementation that sends messages to a queue is:

public class MyVariableTableSubscriber extends VariableTableSubscriber {
    LinkedBlockingQueue<String> actions = new LinkedBlockingQueue<>();

    public MyVariableTableSubscriber() {
        super();
    }

    @Override
    protected void variableChanged(String name, Object oldValue, Object newValue) {
        actions.add("VAR_CHANGED " + name +" " + oldValue + " " + newValue);
    }

    @Override
    protected void variableAdded(String name, Object value) {
        actions.add("VAR_ADD " + name + " " + value);
    }

    @Override
    protected void constantAdded(String name, Object value) {
        actions.add("CONST_ADD " + name + " " + value);
    }

    @Override
    protected void variableRemoved(String name) {
        actions.add("VAR_DEL " + name);
    }

    @Override
    public void clearNonConstants() {
        actions.add("CLEAR_NON_CONST");
    }

    @Override
    protected void tableCleared() {
        actions.add("TBL_CLEAR");
    }

    @Override
    public void onComplete() {
        actions.add("COMPLETE");
    }

    @Override
    public void onError(Throwable throwable) {
        actions.add("ERROR "+throwable.toString());
    }
}

Constructor Summary

Constructors

Constructor	Description
VariableTableSubscriber()	Default Constructor that requests one item at a time.
VariableTableSubscriber(int numRequests)	Constructor with a specific number of initial requests.

Method Summary

Modifier and Type	Method	Description
void	cancel()	Cancels the subscription.
protected void	clearNonConstants()	Called when the non-constant variables have been removed.
protected void	constantAdded(String name, Object value)	Called when a constant is added
void	onComplete()	Method invoked when it is known that no additional Subscriber method invocations will occur for a Subscription that is not already terminated by error, after which no other Subscriber methods are invoked by the Subscription.
void	onError(Throwable throwable)	Method invoked upon an unrecoverable error encountered by a Publisher or Subscription, after which no other Subscriber methods are invoked by the Subscription.
void	onNext(VariableTableAction item)	Method invoked with the next item from the Publisher.
void	onSubscribe(Flow.Subscription subscription)	Method invoked when the Subscription is created.
protected void	tableCleared()	Called when the variable table has been cleared.
protected void	variableAdded(String name, Object value)	Called when a variable is added to the table.
protected void	variableChanged(String name, Object oldValue, Object newValue)	Called when a variable value has changed.
protected void	variableRemoved(String name)	Called when a variable is removed from the table.

Methods inherited from class java.lang.Object

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

Constructor Details

VariableTableSubscriber

public VariableTableSubscriber()

Default Constructor that requests one item at a time.

VariableTableSubscriber

public VariableTableSubscriber(int numRequests)

Constructor with a specific number of initial requests.

Parameters:

numRequests - the number of items to request

Method Details

onSubscribe

public void onSubscribe(Flow.Subscription subscription)

Method invoked when the Subscription is created. Requests the initial number of items specified by numRequests.

Specified by:

onSubscribe in interface Flow.Subscriber<VariableTableAction>

Parameters:

subscription - the subscription

onNext

public void onNext(VariableTableAction item)

Method invoked with the next item from the Publisher. Calls the appropriate method based on the action of the item. For example the variableChanged(String, Object, Object) method is called if the action is VARIABLE_VALUE_CHANGED.

Specified by:

onNext in interface Flow.Subscriber<VariableTableAction>

Parameters:

item - the item

onError

public void onError(Throwable throwable)

Method invoked upon an unrecoverable error encountered by a Publisher or Subscription, after which no other Subscriber methods are invoked by the Subscription. The default implementation does nothing.

Specified by:

onError in interface Flow.Subscriber<VariableTableAction>

Parameters:

throwable - the exception

onComplete

public void onComplete()

Method invoked when it is known that no additional Subscriber method invocations will occur for a Subscription that is not already terminated by error, after which no other Subscriber methods are invoked by the Subscription. The default implementation does nothing.

Specified by:

onComplete in interface Flow.Subscriber<VariableTableAction>

variableChanged

protected void variableChanged(String name,
 Object oldValue,
 Object newValue)

Called when a variable value has changed. Intended to be overridden by subclasses. Default implementation does nothing.

Parameters:

name - name of the variable

oldValue - previous value of the variable

newValue - value of the variable after the change

variableAdded

protected void variableAdded(String name,
 Object value)

Called when a variable is added to the table. Intended to be overridden by subclasses. Default implementation does nothing.

Parameters:

name - the name of the variable which has been added.

value - the value of the variable which has been added.

variableRemoved

protected void variableRemoved(String name)

Called when a variable is removed from the table. Intended to be overridden by subclasses. Default implementation does nothing.

Parameters:

name - the name of the variable which has been removed.

tableCleared

protected void tableCleared()

Called when the variable table has been cleared. Intended to be overridden by subclasses. Default implementation does nothing.

clearNonConstants

protected void clearNonConstants()

Called when the non-constant variables have been removed. Intended to be overridden by subclasses. Default implementation does nothing.

constantAdded

protected void constantAdded(String name,
 Object value)

Called when a constant is added

Parameters:

name - name of variable

value - value of variable

cancel

public void cancel()

Cancels the subscription.