Institut für Informationssysteme

Migratable Web Services

deutsche Version

Description of the project:

Web Services have continuously gained importance in business and research throughout the recent years. With XML (SOAP) based communication between web services and their clients the web service paradigm is almost independent from platforms, operating systems and programming languages. Discovering and binding of web services at runtime lead to a flexible and dynamic architecture. Although, Web services follow the classical client-server model: the client application has to discover the physical location (URIs) of relevant web services and binds to them. This look-up operation can be done using registries like the Universal Description, Discovery and Integration (UDDI). For the rest of the processing between client and service the connection remains static. Although UDDI supports the dynamic binding of a client to a web service it does not distinguish between different instances of the same web service. In some (business) scenarios this model is too inflexible and does not comply with business relations in the real world motivating the paradigm of migratable web services.
Migratable web services are instances of conventional web services that are able to change their executing host without loosing the actual state and the connection to their clients. Migratable web services exceed remote installation of code. As migratable web services have a client-dependent state we may have several different instances of the same web service. Like objects of the same class in object-oriented programming languages the web service instances share the same code but differ in their current state, e.g. the values of variables. To be more precise, a client is not bound to a web service directly but to its personal instance.

In this project we implement an Apache Axis based architecture which allows the seamless migration of arbitrary web service instances between hosts. The connection to the clients is not affected by migration processes as the physical client-server model is abstracted to a logical client server model. A JXTA based P2P grid is used by an infrequently requesting client to discover its personal instance of a web service after multiple unnoticed migrations.

Involved researcher:

Involved students (in alphabetical order):


hammerschmidt / 25.06.2004