I would say that webservices are components but components may not be webservices. The key difference is the communication between software. There are three levels of intersoftware commnication:
First is function level that is function calls where data is exchange thro function signitures and return values. This level requires tightest coupling between software. Second is at component level where messages are used for data exchange. This level is asych communication. Third level is at application level where intercommunication is through mutual agreed XML schema. Webservices are components at this level therefore XML is key technology for webservices. The main advantage is that an enterprise information solution can have applications developed in different platforms and different time frames and even beyond orgnaizaiton boundaries. One trend in technology advance is the way intersoftware communication. COM and Java beans are through interface specification and webservies are through XML schema. Therefore the levels have moved from functions to components to applications and the degree to which coupling software is greately reduced. Jerry --- Anne Thomas Manes <[EMAIL PROTECTED]> wrote: > A web service is an application that exposes its > functionality through a > standards-based interface -- using WSDL and XML > Schema (and eventually > WS-Policy and other description languages) to > describe the interface and > SOAP as its protocol. One of the key advantages of > web services is that the > interface hides the implementation details. > > You can develop the application that implements the > service using any > programming language: .NET, Java, C++, C, PHP, Perl, > Python, Ruby, > JavaScript, Cobol, etc. You should select your > programming language based on > many factors, including application requirements, > time constraints, > developer skills, available frameworks, deployment > constraints, existing > license agreements, etc. > > Based on the selected programming language, you > should then follow best > practices for developing applications in that > language. Most language > communities agree that component-based development > frameworks provide > significant advantages, but there is often a lot of > disagreement as to which > component-based framework is the best. > > For example, there is a big debate in the Java > community regarding EJB > versus POJO (plain old Java objects). Lots of > developers reject the > complexity of the EJB component model. Instead they > use servlets, JSPs, and > ordinary JavaBeans, or they use an open source POJO > component framework such > as Spring or PicoJava. From my perspective, EJB > should be used for only a > small subset of applications that require complex > distributed transactions > or extremely high scalability. For most > applications, EJB is overkill and > the overhead out-weighs the potential scalability > advantages. > > COM+ is old technology and I strongly discourage you > from using it today. It > has been replaced by .NET Enterprise Services, and > it will shortly be > replaced again by Windows Communication Foundation > (WCF aka "Indigo"). In > WCF, you simply use the .NET component model and > annotate your code to add > additional infrastructure functionality such as > transactions and security. > > Anne > > On 2/28/06, kamhayfung <[EMAIL PROTECTED]> > wrote: > > > > I'm looking for formal definitions and comparisons > between (web) > > services and components (e.g. EJB, COM+) to > clarify whether or not > > components are the best or preferred technologies > to implement web > > services. > > > > Any pointers pls? > > > > Kam. > > > > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/service-orientated-architecture/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
