Abstract: |
In this thesis, we present Omnix, a Peer-to-Peer (P2P) middleware framework. P2P middleware
provides an abstraction between the application and the underlying network by providing
higher-level functionality such as distributed P2P searches and direct communication
among peers.
P2P networks build an overlay network, a network on the network. The central idea of
this dissertation is to apply the well-established ISO OSI layered model on P2P middleware
systems. A layered P2P architecture helps to identify separate parts of a complex system,
allows changes to the system without affecting other layers and makes maintenance easier
due to modularization. The main advantages of having such a layered P2P middleware are:
independence from the underlying network and the P2P topology.
This dissertation proposes a P2P middleware architecture consisting of three layers: the
Transport Layer, the Processing Layer and the P2P Network Layer. The Transport Layer
(which can be compared to the Physical Layer of the OSI model) is responsible for providing
an abstraction to the network primitives provided by operating systems or libraries. This
makes Omnix independent from the underlying network protocols and the devices and allows
Omnix to run on heterogeneous devices. The Processing Layer (an analogy to the Data Link
layer) provides an error free connection to remote peers and allows additional services to
be plugged in. The P2P Network Layer comprises the routing algorithm, thus describes the
topology (or structure) of the P2P network.
Omnix has a pluggable architecture that allows different components to be plugged in
based on the requirements of an application, the capabilities of the device the application is
running on, the number of peers involved, etc. Custom-tailored P2P middleware systems can
be constructed, thus, increasing the flexibility of communication architectures that are built
upon it. Applications that use Omnix are provided an API that is not affected whenever the
underlying topology has to be changed or adapted.
Since testing P2P networks is hard to accomplish due to the large amount of peers required
to get significant results, Omnix provides a way of testing P2P applications using this
middleware framework. By replacing the communication layer by a virtual network, it is
possible to simulate a network of virtual peers on a single computer without the necessity of
changing the application on top of it.
Along with Omnix, several plugins are provided to demonstrate the versatility of the
framework. They provide the functionality to run Omnix on normal PCs, on handheld computers
(e.g., Compaq iPAQ) and on Java-enabled mobile phones. |
