Inter Service Dependency Model

In any SOA ecosystem, there are bound to be numerous services. Some of the services in will be core services which will be used by most of the services. If this interdependency is not maintained, it may result in spaghettiof services. To have an ordered SOA architecture, one must rely on proven layered architecture which ensures robustness and independence of non adjacent layers.

To measure inter dependence of services, I have developed a simple but effective model, which I call Inter Service Dependency Model. This model is inspired by DSM (Design Structured Matrix.

In this model, services are viewed from provider and consumer perspective and emphasis is on maintaining layered based architecture principles in SOA ecosystem.



The matrix is divided into three distinct areas. The Solid BLACK region is the demarcation between RED and GREEN. One should fill value in GREEN and RED region cells to illustrate inter dependency of services. This dependency strength generically can be defined as



In a well designed SOA eco system following conditions should exist:

1. Matrix is populated only with Zero and Positive numbers
2. RED region is populated with Zero
3. Black region must not be populated ( pretty obvious)
4. GREEN region should be populated with positive numbers.

Above mentioned conditions still not address adjacent layer dependency only. To address that one should be able to figure out structure of GREENs and may also club services into layers.

Reference:

1. http://www.dsmweb.org/
2. http://ausweb.scu.edu.au/aw08/papers/edited/mehboob/paper.html
3. http://www.stsc.hill.af.mil/crosstalk/2005/11/0511SangalWaldman.html
4. http://www.lattix.com/technology/whatisdsm.php
5. http://en.wikipedia.org/wiki/Dependency_Structure_Matrix