Topaz - A Structured Web Server

Overview

Design and development of webservers must take requirements associated with future extensibility into account. Object technologies have a proven record in the area of large-scale system design. They are well adapted to extensibility requirements, especially when the required additions of functionality cannot be foreseen at design time. Secondly, they provide a basis for permanent in-service re-engineering of the support components, taking advantage of new capabilities and product deliveries.

Topaz demonstrates how use of object technology simplifies the design of web based services. Topaz builds on existing webserver technology using current CGI methods and techniques.

Benefits

The benefits of object invocation for webserver request processing as used in the Topaz architecture are:

1. Webserver interoperability mechanisms that can be used to leverage existing services built around object technologies such as CORBA.
2. Simple extensibility/upgradeability for the server developer and maintainer.
3. Better performance characteristics through using object mechanisms for service instantiation and load balancing.
4. Compatibility with existing standard web server systems: because of the way the structured web server architecture is designed, the basic object support mechanisms can be implemented in CGI and further object services added on to a single CGI middle tier.
5. A testbed for the Java technology developed within Jade, and for other projects involving the need to deliver live services or mobile code in some form.

The proposed webserver substructure architecture provides the benefits of:

• efficient use of finite webserver resources
• a straightforward mechanism for state maintenance across multiple requests
• automatic interoperation with object facilities occupying the CORBA world.

Approach

The approach is to decompose webserver functions into a set of CORBA objects. Incoming requests are intercepted and sent to a fine grained locator (FGL). FGL examines the existence of objects offering the requested service. If a service exists it will be used instantaneously. If not it will be instantiated on the fly, registered and then used. FGL holds a repository of existing services (types and instance).

The architecture of a Topaz structured web server in simple form, showing the Interceptor, Fine Grained Locator, and some of the service objects. Not shown is the Launcher which creates new service instances as required.

Dependencies

This project aims to build on the results of the ANSAweb (dead hyperlink - http://www.ansa.co.uk/ANSA/ISF/) project which delivered its results to ANSA sponsors in December of 1995.

Deliverables

1. Design presentation and document
2. Launcher program and code
3. Locator program and code
4. Demonstrator application
5. Performance testing
6. Technology transfer presentation
7. Final project document and summary.
8. Paper submission for WWW6 conference based on deliverable number 7.

Timescale

The proposed starting date is April, 1996. Estimated completion date is September, 1996.

Contact

For further details, please contact Mark Madsen (msm@ansa.co.uk) or Owen Rees (rtor@ansa.co.uk).