SOA is still an ambiguous topic, especially when it comes to terminology. Terminology is however one of the most important topics for successful SOA, because we require technical and semantic interoperability. Services (with their end users) need to be able to technically connect and need to be able to especially understand each other. Understanding then of course, requires among other things, common terminologies. Now, In order to shed some light into the SOA-terminology-darkness a simple and clear, yet rich, equation surrounding Enterprise Services (ES):
ES Methodology + ES Governance = ES Harmonization
Enterprise Service Methodology
.... ensures that the right thing is done. ES Methodology introduces common Repository-based Modeling and Design, conventions, models, patterns and rules for ‘design' consistency. The methodology forms the core of every single Enterprise Service definition and can directly be related to the correlated Enterprise Service Metamodel (Link on page 43). It allows a coherent, consistent and repeatable approach for the design of services. The premise is that if two or more person in an organization would individually build the same service that the result would exactly be the same service design. In summary, ES Methodology is all about effectiveness.
Important to note is that this methodology is not bound to SAP but - of course -easier to realize with our tools. A very good example here is our current engagement of Partner-delivered Enterprise Services, where we actively teach partners to build services along our methodology. These services can then ultimately be labeled and sold as Enterprise Services by Partners.
+ Enterprise Service Governance
... ensures doing the thing right. ES Governance introduces a dedicated review and control process with several quality gates or milestones for procedural consistency. Within each milestone central SOA architects look into specified artifacts and entities to control the proper application of the methodology. These review gates therewith ensure the design quality of the service. Governance also, for example, ensures that there are just not two people in an organization individually building the same service :P. In summary, ES Governance is all about efficiency.
Important to note is that I herewith refer to Governance of/ for Enterprise Services, not SOA Governance. Latter, is covering far more aspects, such as realizing change management with for example building/ changing skills & resources, establishing a SOA competence center with enterprise wide architectural planning, roadmaps and far more activities.
= Enterprise Service Harmonization
... is then the result of doing the right thing right. This means that mutually exclusive and collectively exhaustive ‘content or functionality' has been achieved within the organization. Mutually exclusive describes the fact that no Enterprise Services overlaps or in any way provides redundant functionality in comparison to another Enterprise Services. Each ES is a unique and easy to understand entity with a clear unique purpose. Collectively exhaustive describes that the overall set of all unique and redundancy free Enterprise Services provides all functionality that is necessary (or available) for the entire organization.
Differentiating now methodology and governance even further, one can say that SAPs Methodology is required for building Enterprise Services. SAPs Governance is considered a best practice. Why? Well, very simple. SAP is big. SAP has a huge set of functionality residing in multiple applications, with different people and various processes. That results in a very thorough and comprehensive governance approach and efforts to really ensure harmonization of our entire (to emphasize here again) entire content/ functionality. Considering a small independent software vendor with potentially only 30 employees this governance approach can be realized by one or two person, whereas SAP has a multitude of these. The methodology to built Enterprise Services is however exactly the same.
So again, our methodology is a must for ES and our governance a best practice. The efforts to achieve harmonization differs thus form organization to organization. Yet, harmonization is what every organization is striving for in an SOA. This is the ultimate difficulty and the ultimate goal.