The conflict over the term "service" can lead to some confusing conversations between developers and operations staff. I have posted earlier on the definition of services in SOA. The ITIL definition is
"A service is a means of delivering value to customers by facilitating outcomes
customers want to achieve without the ownership of specific cost and risks. "
ITSMWatch
Two very different examples of a service in ITIL could be a payroll system and the resetting of a LAN password. The services of an IT organization should be available on a "service catalogue" and the clients of the IT organization can use this catalogue to choose and understand the services they receive.
This is different from an SOA service. An SOA service is a software component which:
• Hides its implementation,
• Is based on standards,
• Is location transparent,
• Is message coupled, and
• Is accessible through defined platform independent interfaces.
The main difference is that an SOA service is a software component in SOA. It is not the service that a help desk provides when they reset your password and it is generally smaller than a whole payroll system. An SOA service can be hidden away from the users in the cloud of application components. Ideally it is granular enough to have meaning to users but a user does not need to be able to interface with a service directly.
There can be coincidental overlap between an SOA service and an ITIL service. A service for paying a bill may also be presented directly to the users of an IT Department or organization and therefore be a service on their catalogue. This only seems to confound the issue. It is safer to assume that ITIL stalwarts and SOA engineers are talking about different things when they refer to a service.
IT Service Management (ITSM) under ITIL however can provide an appropriate means for providing governance for your SOA and for providing the operational platform for your SOA. SOA may contain more component parts than traditional systems and a disciplined approach to configuring, operating and changing these parts is required which is exactly what ITIL offers.
Interestingly ITIL also seems to redefine SOA as "Service Offerings and Agreements" and "Service Outage Analysis" which also makes life complicated.
Notes:
Some good articles on ITIL and SOA follow:
http://www.ca.com/Files/WhitePapers/soa_wp_jlong_33146.pdf
http://www.ibm.com/developerworks/ibm/library/ar-soaitil/
http://www.ebizq.net/blogs/bethgb/2009/03/can_itil_help_fix_soa.php
http://www.biske.com/blog/?p=467
The book I am reading which proffered the payroll as a service example is:
Klosterboer, Larry, 'Implementing ITIL Change and Release Management', IBM Press, 01 Dec 2008.
