Distributed messaging system supporting stateful

Abstract

A distributed messaging system supporting stateful subscriptions is provided. A stateful publish-subscribe system extends the functionality of the content-based approach to include more general state-valued expressions. Stateful subscriptions may refer to one or more message histories and may include more complex expressions. Therefore, subscribers may receive different information than that provided in the published messages. A plurality of broker machines is provided to deliver messages sent by publishing clients toward subscribing clients based upon the contents of the messages and stateful transformations requested by the subscribing clients. Subscription specifications are analyzed by a compiler and converted into a collection of transform objects and view objects. The messaging system builds a structure containing all transform objects and view objects needed for all intermediate and subscribed views of all subscriptions. This messaging system uses this structure to allocate transform objects and view objects to broker machines in the overlay network.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is related to U.S. patent application Ser. No. ______, attorney docket no. YOR920040153US1, entitled “CONTINUOUS FEEDBACK-CONTROLLED DEPLOYMENT OF MESSAGE TRANSFORMS IN A DISTRIBUTED MESSAGING SYSTEM,” filed on an even date herewith, assigned to the same assignee, and incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] 1. Technical Field [0003] The present invention relates to data processing systems and, in particular, to messaging systems in a distributed processing environment. Still more particularly, the present invention provides a distributed messaging system supporting stateful subscriptions. [0004] 2. Description of Related Art [0005] A publish-subscribe messaging middleware is a system in which there are two types of clients. Publishers generate messages, also referred to as events, containing a topic and some data content. Subscribers request a criterion, also called a subscription, spe...

AI Technical Summary

Benefits of technology

[0010] The present invention solves the disadvantages of the prior art and provides a distributed messaging system supporting stateful subscriptions. A stateful publish-subscribe system extends the functionality of the content-based approach to include more general state-valued expressions. Stateful subscriptions may refer to one or more message histories and may include more complex expressions. Therefore, subscribers may receive different information than that provided in the published messages. A plurality of broker machines is provided to deliver messages sent by publishing clients toward subscribing clients based upon the contents of the messages and stateful transformations requested by the subscribing clients. These broker machines form an overlay network. Subscription specifications are analyzed by a compiler and converted into a collection of transform objects and view objects. The messaging system builds a structure containing all transform objects and view objects needed for all intermediate and subscribed views of all subscriptions. This messaging system uses this structure to allocate transform objects and view objects to broker machines in the overlay network.

Problems solved by technology

Publishers and subscribers are anonymous, meaning that publishers do not necessarily know how many subscribers there are or where they are and, similarly, subscribers do not necessarily know where publishers are.

This is a useful concept; however, in their current manifestations, mediators are complex to program, require external database services in order to store and access state, and groups of mediators cannot be automatically combined.

Such an approach is easier to program; however, it can be costly and slow if each new message results in a transaction involving a large number of subscribers.

However, this approach is restricting and limited.

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