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Introduction
Service-based software
The traditional development of software has focused on supply-side issues that are driven by software developers
of technology rather than end-users (Budgen et al., 2004, 2007). For recent years, however, the rapid growth of the internet
technology has changed the role of a service of modern business from the forms of service provided by conventional
businesses. Software, developed and delivered by software vendors, has begun to move from software products to more
profitable software services (IBM-SaaS, 2010). To deal with new demands of the end-users, software can be delivered as a
service focusing on the rapid changing needs of the end users.
Software as a Service (SaaS)
The Software as a Service (SaaS) is a service-based model (Budgen et al., 2007, 2004). The SaaS model consists
of three layers: service description, service integration and service transport. The service integration layer comprises five
service functions: description, discovery, negotiation, delivery and composition.
SaaS is based on a demand-led concept in which a desired service is assembled, delivered and consumed on
demand. By using the SaaS model, end-user services are composed out of smaller services (and so on recursively),
procured and paid for on demand. End-users can generate, compose and assemble a service by gathering services from a
number of service suppliers in order to meet the end-users’ needs at a specific point in time.
Information Broker for Heterogeneous Sources (IBHIS)
‘A proof of concept’ demonstration of the SaaS model is ‘The Information Broker for Heterogeneous Sources’
(IBHIS). The IBHIS project was undertaken by the members of the Pennine Group (researchers from the University of
Durham, Keele University and UMIST), in partnership with Social Service collaborators in Solihull and Keele’s Centre for
Health Planning and Management (Budgen et al., 2007). The aim of this project is to develop the IBHIS broker system to
be a fully service-based approach to large-scale healthcare data integration, gathering from distributed, heterogeneous and
autonomous data sources.
The IBHIS broker has demonstrated the overall set of concepts involved in SaaS by allowing services to be
located on the basis of the data that they provide. According to Figure 1, the IBHIS architecture consists of basic services
used in two forms: statically-bound service and dynamically-bound service. The statically-bound services are the set of
services that are known in advance. They are used within the information broker providing functional tasks, for instance
user interface, user access control mechanisms and query formulation. The dynamically-bound services are the set of
services that are termed as Data as a Service (DaaS). The DaaS is a service supplying information, used where the set of
related information sources is usually regulated dynamically. Consequently, the dynamically-bound services, needed to
perform a task, are determined, located and bound at the time of execution. They use the concept of a Data Access Service
(DAS) to form an interface between the ‘physical’ structure of the data sources, and the broker itself.
