Page 254 - Using MIS

222 Chapter 6 The Cloud
Service-Oriented Architecture (SOA)

The cloud would be impossible without a design philosophy called the service-oriented
architecture (SOA). According to this philosophy, all interactions among computing devices
are defined as services in a formal, standardized way. This philosophy enables all the pieces of
the cloud to fit together, as you will see. However, understanding SOA (pronounced SO-ah) in
depth requires you to learn more computer science than you need as a business professional.
So, the best way for you to understand SOA is via a business analogy.

A SOA Analogy

Figure 6-12 shows a hypothetical arrangement of departments at AllRoad Parts. The Sales
Department receives order requests and follows a process to have them approved for ship-
ping. On request, the Credit Department verifies customer credit as needed to approve or-
ders, and the Inventory Department verifies the availability of the inventory needed to fulfill
an order.
In an informal, non-SOA-type organization, one salesperson would contact someone he
or she knows in Credit and ask something like, “Can you approve an allocation of $10,000 of
credit to the ABC Bicycle Company?” In response the credit person might say, “Sure,” and the
salesperson might note the name of the person who approved the amount. Some days he or she
might remember to record the date; other days, not so. Another salesperson might do some-
thing else, say contact a different person in Credit and ask something like, “I need $5,000 in
credit for Order 12345,” and that other person in Credit might say, “I don’t know, send the order
over, and if I can, I’ll write ‘Approved’ on it.” Other irregular, but similar, interactions could occur
between the Sales and the Inventory departments.
Such operations are definitely not service-oriented. People are asking for credit verification
in different ways and receiving responses in different ways. The process for approving an order
varies from salesperson to salesperson, and possibly from day to day with the same salesper-
son. The records of approvals are inconsistent. Such an organization will have varying levels of
process quality and inconsistent results, and should the company decide to open a facility in
another city, these operations cannot be readily duplicated, nor should they be.
Using SOA principles, each department would formally define the services that it provides.
Examples are:
For the Credit Department:

• CheckCustomerCredit
• ApproveCustomerCredit

Customers
Credit
Department
Sales Request / Response
Order
Requests

Sales
Department

Figure 6-12 Inventory Request / Response Inventory
Approval Request Interactions Department
Among Three Departments