---SOA:
   A service-oriented architecture is essentially a collection of services. These services communicate with each other. The communication can involve either simple data passing or it could involve two or more services coordinating some activity. Some means of connecting services to each other is needed.
---Service:
   A service is a function that is well-defined, self-contained, and does not depend on the context or state of other services.A service is the endpoint of a connection.
---Web Services refers to the technologies that allow for making connections.
---Questions:
   Are you familiar with SOA? 
   What is SOA? 
   What is a Web Service? 
   What is the difference between SOA and Web Services? 
   What is the difference between Web Services and SOAP? 
   What is the difference between SOAP and SOA?
---Most services are built on tools that provide the following components:
       Application and Service Components: Workflow, Business Process Execution, Orchestration

       Service Buses: Connectors, Caching, Policies, Scripting, Messaging
       Infrastructure Components: SOAP bindings, XML parsers, Message service bindings, clustering, replication and high availability
--ESB:
   An enterprise service bus (ESB) is a pattern of middleware that unifies and connects services, applications and resources within a business. it's a new way of looking at how to integrate applications, coordinate resources and manipulate information,
the ESB pattern enables the connection of software running in parallel on different platforms, written in different programming languages and using different programming models.