Handling

Handlers what actually consume message envelopes. When the router routes an envelope and returns a handler instance to the Consumer, the Consumer executes the handler by invoking its pre_handle(), handle(), and post_handle() methods respectively.

Handler

class rabbitleap.handling.Handler(envelope, **kwargs)

Base class for envelope handlers.

envelope is a reference to the given message envelope.

Subclasses MUST implement handle() method.

Methods:

initialize(): initialization hook used to initialize the handler with kwargs.

pre_handle(): pre handling method invoked before handle().

handle(): to be implemented by the subclasses for the actual handling logic.

post_handle(): post handling method invoked after handle().

Handler.initialize(**kwargs)

Initialize handler.

This method is an initialization hook for the handler.

Handler.pre_handle()

Pre handle message envelope.

This method is invoked by the Consumer before invoking handle(). It’s meant for validation and preparation before the actual handling.

Handler subclasses can override this method to add pre handling logic.

Handler.handle()

Handle message envelope.

This method is invoked by the Consumer after invoking pre_handle(). The actual envelope handling should happen in this method.

Handler subclasses MUST implement this method.

Handler.post_handle()

Post handle message envelope.

This method is invoked by the consumer after invoking handle(). It’s meant for clean up and logging after the actual handling

Handler subclasses can override this method to add post handling logic.

Message Handler

class rabbitleap.handling.MessageHandler(consumer, envelope, **kwargs)

Bases: rabbitleap.handling.Handler

Message handler.

This class extens the Handler class with methods used to reject and skip envelopes, also report handling error. It hold a reference to:class:.Consumer instance which does the execution.

Methods:

initialize(): initialization method, a hook initialize the handler with kwargs.

pre_handle(): pre handling method invoked before handle().

handle(): overridden by the subclass implementing the handling logic.

post_handle(): post handling method invoked after handle().

error(): a shortcut for Consumer.error() to raise HandlingError exception.

abort(): a shortcut for Consumer.abort() to reject message.

skip(): a shortcut for Consumer.skip() to skip message handling.

MessageHandler.abort(reason=None)

Abort handling the message.

This method is a shortcut for Consumer.abort().

NOTE: when called inside the handler, the handler should re-raise AbortHandling exception to the consumer if the exception is handled inside it.

Parameters:reason (str) – Reason for aborting handling the message.

MessageHandler.error(error_msg=None)

Raise HandlingError exception.

This method is a shortcut for Consumer.error().

Raise:HandlingError when called.

NOTE: when called inside the handler, the handler should re-raise HandlingError exception to the consumer, in case the exception is handled inside.

Parameters:error_msg (str) – Error message.

MessageHandler.skip(reason=None)

Skip handling the message.

This method is a shortcut for Consumer.skip().

NOTE: when called inside the handler, the handler should re-raise SkipHandling exception to the consumer if the exception is handled inside it.

Parameters:reason (str) – Reason for skipping handling the message.