Le Subscribe: Publish and Subscribe on the Web at Extreme Speed


Nowadays there is a proliferation of selective dissemination of information applications. This is due to the fact that there is more and more dynamic information available through the Web. For example, we can easily find in the Web information concerning stocks, sales, tickets, documents. Web users would like to be notified when new relevant information is produced. A user may be interested in receiving a notification when a given stock reaches a certain value.

We expect this trend to accelerate with time as new devices and communication infrastructures are continuously being introduced, network access technologies are merging (i.e., PDA and mobile phone) and, interoperability between different media is increasing. For instance the third generation mobile networks (3G UMTS) offers much higher bandwidths services than are currently possible. This will further increase the potential for information services and increase the need for highly targeted information dissemination systems. Examples of information services include user-profile-based content delivery, subscription-based notification and targeted advertissement distribution to network participants. In wireless network, push-based messaging including audio, short message service (SMS), e-mail, multimedia messaging, picture messages or pushed advertisement are emerging scenarios.

A system supporting these applications has to be capable of managing millions of users, manage high volatility of users' interests and fliter large quantities of events per unit of time (this number will depend on the application domain). A good candidate paradigm for such applications is the publish and subscribe paradigm. This paradigm is a simple to use interaction model that consists of information providers (publishers), who publish information to the system, and of information consumers (subscribers) who subscribe to issues of interest within the system. The role of publish and subscribe system is to timely send the right information to the right person. Publish and subscribe systems are composed of two main components: the filtering engine and the notification component. The former one computes the subscriptions matching an event while the latter one is responsible for the notification processing.

A big challenge to build content based publish-subscribe systems is to solve the trade-off between (matching) performance and the expressiveness of the publication and subcriptions language they can support. Our research work focuses on designing scalable pattern-matching algorithms which enable powerful subscription languages on complex data. These algorithms are the heart of our two publish and subscribe prototypes called Le Subscribe and WebFilter. Both prototypes aim at Large-scale and High-throughput subscriptions processing for selective information dissemination on the Internet and in Wireless environments.

The main main features of Le Subscribe are:
A new prototype called WebFilter extends Le Subscribe to enable XML processing. It has the following features:
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