ComponentsActiveXBeansCorbaSoap

ComponentsActiveXBeansCorbaSoap - Components COM, ActiveX,...

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    Components COM, ActiveX,  JavaBeans CORBA and SOAP
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    Brad Cox’s IC analogy Software components should be like integrated circuits (ICs)  Or plumbing components? Why?  What are our desiderata for software components? Bertrand Meyer, in  Object Oriented Software Construction : 1. modular  (IC chips, disk drivers, are self-contained: packaged code) a)  compatible  (chips or boards that plug in easily, simple interfaces) b)  reusable  (same processor IC can serve various purposes) c)  extendible  (IC technology can be improved: inheritance) 1) reliable  (an IC works most of the time!) a)  correct  (it does what it's supposed to, according to  specification ) b)  robust  (it functions in abnormal conditions) 2) efficient  (ICs are getting faster and faster!) 3) inexpensive  (ICs prices are falling 4) portable  (ease of transferring to different platforms) 5) timely  (released when or before users want it) What do you think: will any software paradigm answer all our wishes?
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    Programming,  1996 European Conference on Object-Oriented  Programming “A software component is a unit of composition with  contractually specified interfaces and explicit context  dependencies only. A software component can be deployed  independently and is subject to composition by third parties.” Unit of composition – c ombine components to build systems Binary units – black boxes, not source code Contractually specified interfaces –  mechanism for interface  definition, such as Interface Definition Language Independent production – separation of concerns Deployed and composed by third parties – reusable units  assembled like parts supplied by manufacturers
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    Why a component based approach?  Consider two ends of a spectrum: Comm. off the shelf < --- > Custom-made What advantages of COTS software could  components offer to custom-made?  Advantages: Reuse, productivity Scalability Application of engineering techniques
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    Costs of components It takes significant effort to create a software component  that is effectively reusable.   How so? The component needs: to be fully documented;  more thorough testing;  robust input validity checking;  to pass back useful error messages as appropriate;  to be built with an awareness that it  will  be put to unforeseen  uses  a mechanism for compensating developers who invest the  (substantial) effort implied above. 
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    Distributed Component Technologies The goal:   - Integration of  services  for applications on various platforms - Interoperability : let disparate systems communicate 
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ComponentsActiveXBeansCorbaSoap - Components COM, ActiveX,...

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