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OCALA: An Architecture for Supporting Legacy Applications over Overlays

Joseph, Dilip
Kannan, Jayanth Kumar
Kubota, Ayumu
Lakshminarayanan, Karthik
Stoica, Ion
Wehrle, Klaus
Technical Report Identifier: CSD-05-1397

Abstract: The ever increasing demand of new applications coupled with the increasing rigidity of the Internet has led researchers to propose overlay networks as a means of introducing new functionality in the Internet. However, despite sustained efforts, few overlays are used widely. Providing support for legacy Internet applications to access such overlays would significantly expand the user base of the overlays, as the users can instantly benefit from the overlay functionality.

We present the design and implementation of OCALA, an Overlay Convergence Architecture for Legacy Applications. Unlike previous efforts, OCALA allows users to access different overlays simultaneously, as well as hosts in different overlays to communicate with each other. In addition, OCALA reduces the implementation burden on the overlay developers, by factoring out the functions commonly required to support legacy applications, such as tapping legacy traffic, authentication and encryption. Our implementation of OCALA as a proxy requires no changes to the applications or operating systems. We currently support two overlays, i3 and RON, on Linux and Windows XP/2000 platforms. We (and a few other research groups and end-users) have used the proxy over a eleven-month period with many legacy applications ranging from web browsers to remote desktop applications.