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Introduction
  What is REDS
  REDS in a Nutshell
  Credits
  License
  Download
  Contacts

What is REDS

REDS (REconfigurable Dispatching System) is a framework of Java classes to build publish-subscribe applications for large, dynamic networks.

Distributed publish-subscribe applications are organized as a collection of components, which interact by publishing messages and by subscribing to the classes of messages they are interested in. Publish-subscribe applications are built around a publish-subscribe middleware, which provides a dispatcher, responsible for collecting subscriptions and forwarding messages from publishers to subscribers, and a library to access the services of the dispatcher and implement application components.

REDS provides the client API to write publish-subscribe applications and defines a general framework of components, with clearly defined interfaces, to build a distributed dispatcher organized as a set of brokers linked in an overlay dispatching network, which collaborate to route messages from publishers to subscribers.

REDS' innovative features

With respect to other publish-subscribe middleware REDS provides several innovations:

REDS in a Nutshell

Components of an application built using REDS access the publish-subscribe services provided by REDS through an object that implement the DispatchingService interface. It provides methods to subscribe and unsubscribe to classes of messages, to publish messages, to receive subscribed messages, and to reply to them. REDS provides several implementations of the DispatchingService interface, which differ for the protocol used to access the REDS dispatcher. Developers using REDS may define their own format of messages and filters (used to define the classes of messages application components want to subscribe to) by extending the Message class and implementing the Filter interface. Otherwise, they can use the messages and filters already provided with REDS.

The REDS dispatcher is organized as a set of brokers linked together in an overlay dispatching network. Each REDS broker is internally structured in a set of modules grouped in two layers: the Overlay and the Routing layer. The former manages the overlay network that connects brokers, while the latter is in charge of routing messages on top of such overlay. Figure on the right shows the internal structure of a REDS broker.

Overlay

The goal of this layer is to implement the mechanisms to manage the overlay network that connects REDS brokers and to exchange messages on top of it. In particular, it embeds the protocols that keep the overlay network connected when the topology of the underlying network changes (e.g., because some peers leave a peer-to-peer network or as a consequence of mobility in MANETs).

Although in principle a single component could offer all the services above, our experience shows that it is worth separating the details of how data is transported among brokers, from those concerned with building and maintaining the overlay network itself. Therefore, in our architecture the routing layer interacts with a single component implementing the Overlay interface, but the REDS distribution provides also a GenericOverlay class, which implements the Overlay interface by delegating its services to the Transport and TopologyManager components.

Routing

This level offers the very publish-subscribe functionalities: it stores clients' subscriptions and uses the Overlay to route messages from publishers toward subscribers. It includes the following components:

Current version of REDS provides several classes that implements the interfaces defined above. By opportunely choosing them, programmers using REDS may adapt the behavior of the system to their needs. Programmers are also free to implement new versions of these components if none of them fits their specific needs. As an example, one could define a new component implementing the RoutingStrategy interface, which realizes a new routing strategy for messages and subscriptions. If correctly implemented, such component can be combined with existing ones to implement a fully functional, innovative dispatching network with a minimal effort.

For more information on REDS you can read the REDS paper.

Extensions (New!)

The new release of Reds (1.3) features new extensions to the publish subscribe model, namely Location-Aware and Context-Aware routing. The interested reader may find additional information in the Location and Context-Aware REDS papers. If have any question about those please write us! We are also actively developing REDS version 2 with a new routing model and new modules like self-optimization and message recovery modules. If you are interested preliminary versions of REDS2 are available on request.

Credits

REDS is the result of a research effort led by Gianpaolo Cugola and Gian Pietro Picco, which has been carried out at Politecnico di Milano, Italy. While the two researchers designed REDS and guided its development, the implementation of the current REDS prototype has been possible thanks to the contribution of Matteo Migliavacca, Fabrizio Buzzi, Sandro Calzoni, Luca Mottola, and Alessandro Monguzzi.

License

REDS is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation.

REDS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

Moreover, REDS is being provided with no support and without any obligation on the part of Politecnico di Milano, its trustees, faculty, staff, students, or employees, (collectively "Politecnico di Milano" herein) to assist in its use, correction, modification, or enhancement.

Politecnico di Milano will have no liability with respect to infringement of copyrights, trade secrets, patents, or other intellectual property rights or values by others' use of REDS. In no event will Politecnico di Milano be liable for lost revenue, lost profits, or any general, special, indirect or consequential damages under any theory of liability whatsoever.

Download

To use REDS you must a recent Java Development Kit installed. You can download last version of the JDK for the major platforms from the Sun's Java site. REDS should work with any recent version of the JDK. It has been developed and tested with JDK v1.4 both under Linux and Windows.

REDS V1.3 (Stable)

Current version of REDS is "1.3.0" (description above refers to this version). This version is the most tested, but is not maintained any more, only grave bugs, if any, may be backported. If you are interested in even older versions see the very old REDS page.

To compile reds yourself download the reds source package and read the README file included (you need ant).

REDS V1.5 (Experimental)

This version features a new, better design of the overlay modules and is currently used by us and our students, we suggest you'll give it a try and report back to us any problem you might encounter.

ManetTreeOverlayMgr V.1.0

The component that implements the Tree Overlay Manager for MANET environment (see "Tree Overlays for Publish-Subscribe in Mobile Ad Hoc Networks" for reference) is also provided as a separate package.

Contacts

For any question about REDS you can contact one of its authors: Gianpaolo Cugola and Gian Pietro Picco.