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18 Cards in this Set

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services

an abstract description of some unit of business functionality usually described in terms that are meaningful from both a business and the technical perspective


- this defines a service as a logical entity


- in order to be used , a service must be implemented by a service provider and accessed over a network by a service consumer or service requester

service-oriented architecture

- by combining a set of services it is possible to build applications, and this way structuring software

characteristics of services

- have well defined interfaces


- using standard communication protocols


- services are discoverable through a repository


- reside on providers servers


- they are autonomous


- loosely coupled hiding implementations


- can be composed combined to build up more compex functionality


- aim to be reusable



properties of services

- statelessness


- location transparency



statelessness

- responds to each request as a one-off, without retaining any memory of previous requests


- this reduces complexity


-it also allows increased demand to be dealt with by simply deploying more copies ofthe service or component

location transparency

- clients can use the service without knowing its location


- components can be location transparent using a logical name instead a physical address

find, bind and invoke cycle

- find the service in the repository


- bind and invoke the service from the provider

elements of find, bind and invoke

- the consumer


- the service : each service has a description that specifies how the client can interact with it. The service description will define the signature of the service and may describe other aspect of the contract


- the provider; which is the platform on which the service is implemented.It accepts and executes requests from clients


- the registry (or locator) which allows the clients to find the service

types of services

- utility services


- business services


- coordination services

utility servides

provide some generic functionality useful in a wide range of applications

usiness services

implement a specifix business function

coordination services

coordinate workflows composed of a number of individual services



other classification of services

- task- oriented


- entity - oriented

task-oriented services

related to business activities (business processes)



entity-oriented services

related to business entities (business objects)

service orchestration

choose suitable service and then compose them into a workflow so the services are invoked in a proper sequence

composing services within SOA

- design workflow and specify what services will be needed


- using the registry, discover services


- from the candidates select the suitable set of services


- orchestrate the chosen services according to the workflow


- test the application and correct any faults

advantages of SOA

- agile and flexible response: SOA supports a flexible business model that can respond quickly to changes, new opportunities or competitive threats


- less duplication: if different parts of a business require the same function, it can be packaged as a service and made available for reuse


- integration of legacy applications: legacy software can be wrapped as a service and made to interoperate with other applications


- use of third-party services: systems can easily incorporate functions


- language independence: services written in different languages can interoperate using standard protocols