What are the important principles of SOA (Service oriented Architecture)?
Posted on: November 7, 2011
SOA is based on four important concepts:-
• Boundaries are well defined
In SOA, everything is formalized. The client who is consuming the service does not need to know
how the implementation of the service is done. If you look at some old methodologies of
communication like DCOM. Any changes at server level the client also has to change. Therefore,
the server and client implementation was so much bound that changes need to be done at all
places. In SOA, the rule is if you do enhancement you do not need to change anything at the
client. SOA based application only understands that there is an end point, contract, and bindings.
• Services evolve
Change is the law of nature and services will evolve. In SOA, services can be versioned and you
can host those services in new ends. For instance, you have a service called as “Search Tickets
(Ticket Number) “which gives details based on Ticket Number and its exposed on end point
“ep1”. Tomorrow you want make your Search Tickets service more useful by also providing an
extra option of allowing him to search by passenger name. Therefore, you just declare a new end
“ep2” with service “Search Tickets (Ticket Number, Passenger Name)”. So the client who is
consuming the service at end ep1 continues and at the other end, we have evolved our service by
adding new ends ep2.
• Services share only schemas and contracts
Services use Schemas to represent data and contracts to understand behavior. They do not use language dependent types or classes in order to understand data and behavior. XML is used to define schemas and contracts. Due to this, there is not heavy coupling between environments.
• Service compatibility is policy based
Policy describes the capabilities of the system. Depending on policies, the service can degrade to
match the service for the client. For instance your service needs to be hosted for two types of
client one which uses Remoting as the communication methodology while other client uses
DCOM. An ideal SOA service can cater to both of them according to there communication
policies.
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