org.mule.runtime.extension.api.runtime.source

Class PollingSource<T,A>

java.lang.Object

org.mule.runtime.extension.api.runtime.source.Source<T,A>

org.mule.runtime.extension.api.runtime.source.PollingSource<T,A>

Type Parameters:

T - the generic type for the generated message's payload

A - the generic type for the generated message's attributes

public abstract class PollingSource<T,A>
extends Source<T,A>

A Special kind of Source which automatically handles polling, idempotency and watermarking. As a result of the poll, many items can be obtained and dispatched for execution, each one as a standalone Message.

The SDK will automatically add a <scheduling-strategy> parameter and the runtime will use that strategy to automatically schedule executions of the poll(PollContext) method. The PollContext will be used to dispatch the obtained items, optionally enabling features like watermarking and idempotency.

Since:

1.1

Field Summary

Fields

Modifier and Type	Field and Description
static String	IDS_ON_UPDATED_WATERMARK_OS_NAME_SUFFIX
static String	OS_NAME_MASK
static String	OS_NAME_PREFIX
static String	RECENTLY_PROCESSED_IDS_OS_NAME_SUFFIX
static String	UPDATED_WATERMARK_ITEM_OS_KEY
static String	WATERMARK_ITEM_OS_KEY
static String	WATERMARK_OS_NAME_SUFFIX

Constructor Summary

Constructors

Constructor and Description
PollingSource()

Method Summary

Modifier and Type	Method and Description
protected abstract void	doStart() Implement this method to perform custom starting logic.
protected abstract void	doStop() Implement this method to perform custom stopping logic.
abstract void	onRejectedItem(Result<T,A> result, SourceCallbackContext callbackContext) If one of the items dispatched through PollContext.accept(Consumer) were rejected (either by watermarking, idempotency, server overload, etc.), this method is to be used to released any resources associated to the given result.
void	onStart(SourceCallback<T,A> sourceCallback) This method will be invoked by the runtime to make the source start producing messages.
void	onStop() This method will be invoked by the runtime to make the source stop producing messages.
abstract void	poll(PollContext<T,A> pollContext) This method is responsible for obtaining the items to be dispatched and communicate them through the pollContext using the PollContext.accept(Consumer) method.

Methods inherited from class java.lang.Object

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

Field Detail

OS_NAME_PREFIX

public static final String OS_NAME_PREFIX

See Also:

Constant Field Values

OS_NAME_MASK

public static final String OS_NAME_MASK

See Also:

Constant Field Values

WATERMARK_OS_NAME_SUFFIX

public static final String WATERMARK_OS_NAME_SUFFIX

See Also:

Constant Field Values

RECENTLY_PROCESSED_IDS_OS_NAME_SUFFIX

public static final String RECENTLY_PROCESSED_IDS_OS_NAME_SUFFIX

See Also:

Constant Field Values

IDS_ON_UPDATED_WATERMARK_OS_NAME_SUFFIX

public static final String IDS_ON_UPDATED_WATERMARK_OS_NAME_SUFFIX

See Also:

Constant Field Values

WATERMARK_ITEM_OS_KEY

public static final String WATERMARK_ITEM_OS_KEY

See Also:

Constant Field Values

UPDATED_WATERMARK_ITEM_OS_KEY

public static final String UPDATED_WATERMARK_ITEM_OS_KEY

See Also:

Constant Field Values

Constructor Detail

PollingSource

public PollingSource()

Method Detail

onStart

public final void onStart(SourceCallback<T,A> sourceCallback)
                   throws org.mule.runtime.api.exception.MuleException

This method will be invoked by the runtime to make the source start producing messages.

Each generated message will be passed back to the runtime through the given sourceCallback for processing.

This method should throw an exception if the source fails to start, but any other exception encountered during the process of generating messages, should be communicated to the runtime through the SourceCallback.onConnectionException(ConnectionException)} method.

Only the runtime should invoke this method. Do not do it manually

Specified by:

onStart in class Source<T,A>

Parameters:

sourceCallback - a SourceCallback

Throws:

org.mule.runtime.api.exception.MuleException - If the source fails to start.

onStop

public final void onStop()

This method will be invoked by the runtime to make the source stop producing messages.

This method should not fail. Any exceptions found during the stop process should be logged and correctly handled by the source, but after invoking this method the source must:

• Stop producing messages
• Free any allocated resources
• Be capable of being restarted

Only the runtime should invoke this method. Do not do it manually

Specified by:

onStop in class Source<T,A>

doStart

protected abstract void doStart()
                         throws org.mule.runtime.api.exception.MuleException

Implement this method to perform custom starting logic. Remember that the runtime is polling automatically

Throws:

org.mule.runtime.api.exception.MuleException

doStop

protected abstract void doStop()

Implement this method to perform custom stopping logic.

poll

public abstract void poll(PollContext<T,A> pollContext)

This method is responsible for obtaining the items to be dispatched and communicate them through the pollContext using the PollContext.accept(Consumer) method.

See the PollContext documentation for more information on how to use it and the options available

Parameters:

pollContext - the polling context

onRejectedItem

public abstract void onRejectedItem(Result<T,A> result,
                                    SourceCallbackContext callbackContext)

If one of the items dispatched through PollContext.accept(Consumer) were rejected (either by watermarking, idempotency, server overload, etc.), this method is to be used to released any resources associated to the given result.

Parameters:

result - a rejected item

callbackContext - the associated SourceCallbackContext