SCA (Service Component Architecture)

Service Component Architecture (SCA):-
It's a set of specifications that defines an assembly model for composite services and also provides a programming model to build applications which are SOA-based.The composite service is having a well defined assembly of all the components involved in your application and ready to be deployed. You don't need to deploy the individual components separately. All will be handled by SCA. All the assembly information is stored in an SCA Descriptor.
SCA is part of OASIS (Organization for the Advancement of Structured Information Standards), a not-for-profit consortium that drives the development, convergence and adoption of open standards.

Service Component Architecture specifications:-
The set of specification can be split into four main elements: the assembly model specification, component implementation specifications, binding specifications, and the policy framework specification.
(i)Assembly model specification:-This model defines how to specify the structure of a composite application. It defines what services are assembled into a (Service Oriented Business Applications) SOBA and with which components these services are implemented. The assembly model is defined with XML files.
(ii)Component implementation specifications:- These specifications define how a component is actually written in a particular programming language ex:- Java , BPEL, C++ or C code.
(iii)Binding specifications:- these specifications define how the services and references using different transports type. Binding types can be configured for both external systems and internal wires between components. The SCA service binding type should only be used for communication between composites and components within an SCA domain.
(iv)Policy framework specification:-describing how to add non-functional requirements to services,such as security of service defination. Two kinds of policies exist: interaction and implementation policies. Interaction policies affect the contract between a service requestor and a service provider. Examples of such policies are message protection, authentication, and reliable messaging. Implementation policies affect the contract between a component and its container. Examples of such policies are authorization and transaction strategies.
Deployment and the Service Component Architecture:-
SCA composites are deployed within an SCA domain.

SCA vs SOA:-
SCA focuses on the assembly of various components to provide an easier design and deployment while SOA provides an architecture or style to design and develop the individual components.So, we create components with SOA and assemble them using SCA mainly to make the deployment easier.