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18 Cards in this Set
- Front
- Back
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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 |
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service-oriented architecture |
- by combining a set of services it is possible to build applications, and this way structuring software |
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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 |
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properties of services |
- statelessness - location transparency |
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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 |
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location transparency |
- clients can use the service without knowing its location - components can be location transparent using a logical name instead a physical address |
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find, bind and invoke cycle |
- find the service in the repository - bind and invoke the service from the provider |
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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 |
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types of services |
- utility services - business services - coordination services |
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utility servides |
provide some generic functionality useful in a wide range of applications |
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usiness services |
implement a specifix business function |
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coordination services |
coordinate workflows composed of a number of individual services |
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other classification of services |
- task- oriented - entity - oriented |
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task-oriented services |
related to business activities (business processes) |
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entity-oriented services |
related to business entities (business objects) |
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service orchestration |
choose suitable service and then compose them into a workflow so the services are invoked in a proper sequence |
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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 |
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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 |
