com.bea.b2b.protocol
Interface PlugIn

public interface PlugIn

The PlugIn interface represents a generic logic plug-in. Logic plug-ins are individual components or modules that perform specialized processing of business messages as they pass through the c-hub. At run time, logic plug-ins can intercept, process, and output business messages.

Author:

Copyright © 2000, 2001 BEA Systems, Inc. All Rights Reserved.

Field Summary

static int	EXCEPTION_CONTINUE Indicates that processing should continue to the next logic plug-in if a PlugInException is thrown.
static int	EXCEPTION_STOP Indicates that processing should stop at this logic plug-in if a PlugInException is thrown.
static int	EXCEPTION_UNWIND Indicates that processing should unwind if a PlugInException is thrown.

Method Summary

int	exceptionProcessingModel() Gets the current setting of the exception processing model (continue, stop, or unwind).
java.lang.String	getName() Gets the name of this logic plug-in.
void	init(java.util.Hashtable properties) Initializes this logic plug-in one time using the specified initialization settings.
void	process(MessageEnvelope env) Processes the specified message envelope.
void	shutDown() Shuts down this logic plug-in.
void	unwind(MessageEnvelope env, java.lang.Throwable t) Unwinds changes made by this logic plug-in.

Field Detail

EXCEPTION_UNWIND

public static final int EXCEPTION_UNWIND

Indicates that processing should unwind if a PlugInException is thrown. The business message does not continue to the next logic plug-in in the chain.

Use this option to reject a business message; to prevent its further progress through the c-hub; and to undo any changes made by this plug-in, along with any changes made by previous plug-ins in the chain. If an exception is thrown and this is the exception processing model, then the unwind method in this logic plug-in, as well as the unwind methods in all previous plug-ins in the chain, are invoked in reverse order. In effect, unwinding cancels all changes made by the chain.

EXCEPTION_CONTINUE

public static final int EXCEPTION_CONTINUE

Indicates that processing should continue to the next logic plug-in if a PlugInException is thrown.

Use this option to allow a business message to continue through the c-hub even if an error occurs during the execution of this logic plug-in.

EXCEPTION_STOP

public static final int EXCEPTION_STOP

Indicates that processing should stop at this logic plug-in if a PlugInException is thrown. The business message does not continue to the next logic plug-in in the chain.

Use this option to reject a business message and prevent its further progress through the c-hub.

Method Detail

exceptionProcessingModel

public int exceptionProcessingModel()

Gets the current setting of the exception processing model (continue, stop, or unwind).

Returns:

int One of the following values:

EXCEPTION_UNWIND (0) if the chain should unwind if an exception is thrown.

EXCEPTION_CONTINUE (1) if the chain should ignore the exception and continue processing the business message with the next logic plug-in.

EXCEPTION_STOP (2) if processing should stop at this logic plug-in.

init

public void init(java.util.Hashtable properties)
          throws PlugInException

Initializes this logic plug-in one time using the specified initialization settings.

Parameters:

properties - Name-value pairs that specify initialization information.

Throws:

PlugInException - If an error occurred during initialization.

shutDown

public void shutDown()
              throws PlugInException

Shuts down this logic plug-in. Use method to provide for an orderly shutdown if the logic plug-in is being removed.

Throws:

PlugInException - If an error occurs during shutdown.

getName

public java.lang.String getName()

Gets the name of this logic plug-in.

process

public void process(MessageEnvelope env)
             throws PlugInException

Processes the specified message envelope.

The process() method is invoked when processing a business message at various stages. When invoked, each logic plug-in has access to the information about the business message up to that point of the processing. What may be changed, however, is limited.

Parameters:

env - Message envelope containing the business message information gathered up to this point. Provides a place to store additional information as needed for processing this business message.

Throws:

PlugInException - If an error occurred during processing.

unwind

public void unwind(MessageEnvelope env,
                   java.lang.Throwable t)

Unwinds changes made by this logic plug-in.

The unwind() method is invoked automatically when an exception occurred during execution of a subsequent logic plug-in in the chain. In that subsequent logic plug-in, the exception processing model was configured to unwind the entire chain if an exception was thrown. Developers should implement this message to undo any changes made by this logic plug-in. For example, if this logic plug-in adds a record to a database, this method should removing the record.

Parameters:

env - Message envelope that was passed to process, possibly containing extra information from subsequent logic plug-ins in the chain.

t - Exception that triggered the unwind.