Migratable Web Services
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
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.
- Dipl.-Inf. Beda Christoph Hammerschmidt (former)
Involved students (in alphabetical order):
- Ivo Iken (student research project)
- Frank Müller (student research project)
hammerschmidt / 25.06.2004