On the Reference Architecture for SOA Adoption

While talking with various people and thinking over the case of S.O.A. (note not SOA) in order to explore in more depth the holistic view needed, i came across Hariharan’s post on Reference Architecture for SOA Adoption. Hariharan states:

Fundamental objective of SOA is aligning your IT capabilities with business goals. SOA is not just IT architecture nor business strategy. It should be perfect combination of IT infrastructure and business strategy. So, when we are planning for SOA adoption, we need a strong roadmap and blueprint. Reference architecture model will be a blueprint of SOA.
Reference architecture is like a drawing of your corporate building. Before and after construction, you need blueprint for verification and reference. Similar to that SOA reference architecture could be a reference model for your enterprise business system. Reference architecture should be defined properly during the SOA roadmap definition phase. Refer my last blog in which I was talking about SOA roadmap.
Fundamentally, while defining reference architecture model for corporate, we should consider the following components as part of architecture.
1. Infrastructure and components services
2. Third party communication and data sharing services
3. Business rules services
4. Business process services
5. Data sharing and transformation services
6. Identity and Security Services
7. Packaged Application access services
8. Integration and Event management services
9. Presentation Services
10. Registry and Repository
11. Messaging and Quality
12. Governance
Currently, if you look at the SOA market, there are many product and service providers comes up with its’ own SOA reference architecture. Many major SOA players like IBM, TIBCO, Web Methods, BEA Oracle and MGL has defined reference architecture based on their product catalog and services. If we refer, all has its own model with explanation which may puzzle the SOA adaptors to choose the right approach. One important point should be remembered that product vendor or service provider’s reference model may not suit for your requirements completely. We should consider that as just one of the reference point to finalize the vendor. We should design the right blueprint model for our corporate and SOA need. This is a crucial step that should be planned as part of the SOA implementation roadmap.

Good starting point. But more or less, again the ‘bird eye’ view needed for S.O.A., is not complete. The reason, is services (and actually web-services) oriented view. As stated here S.O.A. is more than integration. It is integration as well, as is about the following of strategies and the future of the in hand infrastructure. So as concerning the types 1,2,6,8 and 12, the reference architecture should avoid or be irrelevant (as possible) to the ‘marketing effect’ proposed by vendors, as stated here. This last issue is recognized in the above statement in the last paragraph when stating :

“Many major SOA players like IBM, TIBCO, Web Methods, BEA Oracle and MGL has defined reference architecture based on their product catalog and services. If we refer, all has its own model with explanation which may puzzle the SOA adaptors to choose the right approach. One important point should be remembered that product vendor or service provider’s reference model may not suit for your requirements completely”

but not enough explored. In any way, i am not against any vendor, or trying to construct a polemic view against them when referring to ‘marketing effect’. They are trying to do business and make money, extent their ROIs and so on. Thats ok. My point is that we must have in mind the inner or hidden points on every co-operator when making our business or working.

So keeping in hand the 12 above points, but we have to be more holistic and therefore more concrete and safe in our reference. This reference is going to be the ground to explore our enterprise niches and evolve through market changes. A nice starting point in what a reference architecture should look like, is proposed from OASIS, among others proposals and standards, in SOA Reference Architecture. Compliant to this reference is the Conceptual Integration Technical Reference Architecture from the Washington State Department of Information Services. In the conceptual Integration Technical R.A. there is this diagram:

The conceptual reference architecture depicted in the diagram above (and defined in this document) adopts the Service-Oriented Architecture Reference Model (SOA-RM) developed by the Organization for the Advancement of Structured Information Standards (OASIS).

The SOA-RM defines its purpose as follows:

“A reference model is an abstract framework for understanding significant relationships among the entities of some environment. It enables the development of specific architectures using consistent standards or specifications supporting that environment. A reference model consists of a minimal set of unifying concepts, axioms and relationships within a particular problem domain, and is independent of specific standards, technologies, implementations, or other concrete details.” ([SOA-RM], p. 4).

“The goal of this reference model is to define the essence of service oriented architecture, and emerge with a vocabulary and a common understanding of SOA. It provides a normative reference that remains relevant for SOA as an abstract and powerful model, irrespective of the various and inevitable technology evolutions that will impact SOA.” ([SOA-RM], p. 4).

As you can see, the Reference is quite abstract. While the SOA-RM is a powerful model that provides the first vendor-neutral, open-standard definition of the service-oriented approach to integration, its abstract nature means that it is not capable of providing the architectural guidance needed for the actual design of integration solutions (or integrated software systems). That guidance comes from the definition of a reference architecture that rests on the foundation of the reference model’s concepts. The reference architecture builds on those concepts by specifying additional relationships, further defining and specifying some of the concepts, and adding key (high-level) software components necessary for integration solutions.

In the diagram above, SOA-RM concepts are shaded yellow. Concepts and components particular to the conceptual reference architecture defined by this document are shaded cyan. Relationships between concepts (indicated by arrows) are defined in the SOA-RM if the arrows connect concepts shaded yellow. Relationships between cyan-shaded concepts or between cyan-shaded and yellow-shaded concepts are particular to the reference architecture.

In order to conclude with Hariharan’s 12 points, which they try to describe and define in a next detailed plan the web services characteristics, we need to have some preliminaries which should work as the base for the next step Hariharan’s analysis:

Firstly, in the context of the organisation in hand (for whom we will define a more solid S.O.A. Reference Architecture), there should be an analysis of the models that exist and the models that we will going to need in the near future (obtained from the strategic decisions in short and long term of the organisation). So analysis of Models of the various entities that play crucial role in the infrastructure. In general these entities lying into 2 main categories:

1. Data Modelling
2. Generic Entity Modelling

What are the nature and model of the data need to be interchanged inside the infrastructure? what formats, categories and relations (dependencies) they follow? This analysis some times maybe needed in a system’s view note. From the point of view that the main system A used in the organisation is handling this data inside it (e.g. time/date/currency/locationGIS/Post code etc…).

What are the main compound entities that they exist and should be interchanged inside the organisation’s infrastructure? How they depend on the predefined data models above? E.g. Customer, Order, Products etc which they will be analysed in the context of main data models and their dependencies and more over, they will incorporate any missing data (used) elements missing from the Data Modelling analysis, depicting relations hierarchies etc. (Usually any missing attributes for the Data Modelling, should be declared and bound on the Entities relations and modelling).

So, now, we can describe our flows (existing) and found the business and IT rules that are needed in order to be able to have some services on the fly or from compounding existing ones. These rules and analysis, will show as if there is a need for the ‘canonical modelling’ that we are using. Depends of coarse on the systems used, to be used and therefore from the strategic decisions taken by the organisation’s next steps (e.g. in Telco's double/triple play which demand an extension to the product models) and of coarse from the vendors compliant modelling schemes of the existing or new systems to be used. Therefore, Hariharan’s list is extending to:

A1.1. Existing Data Modelling
A1.2. Existing Entities Modelling
A1.3. To-Be Data Modelling
A1.4. To-Be Entities Modelling
1. Infrastructure and components services
2. Third party communication and data sharing services
3. Business rules services
4. Business process services
5. Data sharing and transformation services
6. Identity and Security Services
7. Packaged Application access services
8. Integration and Event management services
9. Presentation Services
10. Registry and Repository
11. Messaging and Quality
12. Governance

Now we have the flows parts. Again, having the A1.1-A1.4, we can construct the existing data and entities flows, meaning a more generic Business flows that although they correspond to business analysis, they include the IT –systems steps for complying with the Modelling restrictions by organisation’s infrastructure. These are not only services, although if we generalise the term service, we are in. There might be p2p systems interconnections, hidden to the business flow for demanding, retrieving and consolidating data and so on. \

So we should obtain also an

A2.1 Existing Flows
A2.2 New-proposed Flows

from this point we should be able, having

a) our system’s capabilities
b) our modelling rules

The candidate services, which comply with A2.1 and A2.2 and create the web services (or the RPCs, XMLs, SQLs and so on) for obtaining the repository of available actions. So the list becomes:

A1.1. Existing Data Modelling
A1.2. Existing Entities Modelling
A1.3. To-Be Data Modelling
A1.4. To-Be Entities Modelling
1. Infrastructure and components services
2. Third party communication and data sharing services
A2.1 Existing Flows
A2.2 New-proposed Flows
3. Business rules services
4. Business process services
5. Data sharing and transformation services
6. Identity and Security Services
A6.1. Services Decomposition Strategy
7. Packaged Application access services
8. Integration and Event management services
9. Presentation Services
10. Registry and Repository
11. Messaging and Quality
12. Governance and Orchestration

With these in mind we should be able to develop an Decomposition Strategy (A6.1 in the list) by which we should be able to deconstruct and reconstruct meaningful information from existing services, categorise all the possible services to be used in the organisation, be able to have loosely coupled services and explore with the best possible way under the organisation’s context the services orchestration abilities and of coarse re-usability. In all the above we should have in mind Mike Kavis post concerning the Top 10 Reasons Why People Make SOA Fail.

[

1. They fail to explain SOA's business value.
2. They underestimate the impact of organizational change.
3. They fail to secure strong executive sponsorship.
4. They attempt to do SOA "on the cheap."
5. They lack the required skills to deliver SOA.
6. They have poor project management.
7. They think of SOA as a project instead of an architecture.
8. They underestimate the complexity of SOA.
9. They fail to implement and adhere to SOA governance.
10. They let the vendors drive the architecture.

]

If you have any additions or need help constructing a more concrete and specific Reference model for your instance, give a drop. All comments are welcomed.