Terminology

The SCA specifications 1 collectively define many terms that are used throughout the Tuscany SCA implementation, for example, SCADomain, Composite, Component, Service, Reference. Tuscany itself uses a few terms that are worth explaining.

Distributed Domain

An SCA Domain that is "distributed over a series of interconnected runtime nodes".

Runtime

A runtime groups together one or more (distributed) nodes. It describes the compute resources that will run the components of an SCA Domain.

Node

Provides an environment inside which SCA component instances execute. It's an operating system process, separate from other Nodes. Its form may be as simple as a single Java VM or it may take the more scalable and reliable form, such as a compute cluster.

Each node must be capable of supporting at least:

• one implementation type
• one binding type (which may be restricted to binding.sca)

A node must be able to expose the service endpoints required by the components it runs. It must be able to support the client technology for the references of associated components.

Node Domain

The part of a Distributed Domain that runs on a Node.

Component Instance

The running component that services requests. A single component definition in a SCDL file may give rise to one or more component instances depending on how the component is scoped (using the @Scope annotation).

References

1 http://www.osoa.org/display/Main/Service+Component+Architecture+Specifications