What is a Service?

More and more we start to see articles on the web which are comparing Service Management with Service Oriented Architecture. ITIL is an integrated set of best-practice recommendations with common definitions and terminology which support many IT processes such as Incident management, problem management, change management, configuration management, etc. There is plenty of literature on the web which explain what are these best practices, how we run a program, and how this framework relate to IT Governance.

On the other side, we have SOA, Service Oriented Architecture, which is often associated to BPM, Business process Management. A Business process is a set of automated or non-automated activities, or tasks, exchanging data, where we define flows, and assign roles. An SOA enable a BPM initiative by associating services to task. These services are generally speaking IT components launched by a set of specific SOA technologies such as SOAP, XML, HTTP, WSDL, etc.

When comparing Services in Service Management terms and Services in SOA terms, there is very often some sort of confusion.

ITIL is focused on the provision of services by the IT department to the customer/user. Now these services which are used by the user/customer can take the form of applications that they use (e.g. email services, components of HR systems, ERP and financial systems) or other services which are utilized, such as internet access, printing services, etc. SLAs are then determined for each particular service. Now ITIL encourages the IT department to view these services and determine the underlying technologies which are required to provision these services. For example, UNIX or Windows Servers, Network equipment, Printers, etc. and to identify each outside party that may then provide these underlying technologies. OLA and underpinning contracts are then used to ensure that these parties perform their duties so that the IT department can then fulfil their SLAs.

A SOA Service is defined as a unit of work to be performed on behalf of some computing entity, such as a human user or another program. SOA defines how two computing entities, such as programs, interact in such a way as to enable one entity to perform a unit of work on behalf of another entity. Service interactions are defined using a description language. Each interaction is self-contained and loosely coupled, so that each interaction is independent of any other interaction.

We observe that the SOA Service is much more granular that an IT Service and finally, the latest is maybe the aggregation of several SOA Services…

In other words, SOA and Service Management are not identical in terms of Services definition and this creates lots of confusion in the IT Community. Service Management can be utilized to manage an SOA implementation or solution or the ITIL processes could handle SOA Services as software/hardware components, but Service Management is not a subset of SOA.