The ASP-NET (Application Service Providers NETwork) integration and interoperability platform constitutes the operational and management infrastructure that enables the integration and interoperability of separate online applications. The integration platform promotes interoperability through extensive use of XML-based standards and adoption of the Web services concept for the development of PSS. Important provisions of the integration platform also include: security, management and adaptation.
Web services can be described as software applications identified by a URL, whose interfaces and bindings are capable of being defined, described, and discovered as XML artefacts. A Web service supports direct interactions with other software applications using XML based messages exchanged via Internet-based protocols (e.g. HTTP). Web Services applications constitute loosely coupled Web components that encapsulate other software components and can bind to each other dynamically. Therefore they are characterised by support for just-in-time integration, dynamic service discovery and invocation and they promote encapsulation thus facilitating application development and reusing of existing infrastructure.
Applications integration and interoperability have a variety of definitions and as many solutions that address aspects of the problem. These solutions could be grouped in the following four broad categories, based on:
- File transfer,
- Shared database,
- Remote procedure call and
- Messaging bus.
The ASP-NET platform utilises a combination of the three last integration patterns named above. With the exception of the typical file exchange approach, the other three approaches have been used in various parts of the project architecture. The project developments utilise the shared database and remote procedure call, based on Web services, to achieve the basic integration between the applications.
The shared database approach is used as a method to solve semantic integration issues (i.e. shared identity management between applications) and as a means to avoid replication of information common in all three ASP-NET applications. An LDAP server assumes the role of the shared database, which is the standard repository for directory information (i.e. users, organisations, etc.).
The remote procedure call approach is based on the utilisation of Web services technology for the description of the shared (public) interfaces of the applications (using the WSDL standard), and the SOAP (over HTTP) standard is used for the exchange of information and the remote interface invocation.
The ASP-NET platform also contains a portal component. The portal services provide the aggregation and integration of the ASP-NET application services at the presentation layer (e.g., HTML) and constitute the central access point for their utilisation. Moreover, it is the site where the end-user is provided with the appropriate user interface for the personalisation of the services (e.g., selection of the applications, configuration of applications, configuration of delivery parameters, etc.).
The portal initiates the interaction between end-user and the application services according to the users personalisation parameters, and relays the handling of the service requests to the application services. During the handling of these transactions, the portal interacts with the security and the systems management components as well as with the application services involved. The portal has been built with the Java programming language.
The selected architecture ensures that the requirements imposed for the transparent integration of applications up to the presentation level are met. The constraints imposed to the application services by the integration, security and systems management infrastructure have been minimised, in order to provide a solution as open as possible. The developed platform facilitates the formation of networks of providers (ASP networks) to deliver and support software products and relevant services in the market.