Jerry, Yes, objects are a great way to implement services. It's better to think about software design, especially in the context of an SOA, in terms of functions rather than things.
Yes, an object has a function. But the business more naturally thinks about "getting customer data" than about "the customer is an object on which you perform a get function." It is important to design services that can be implemented using a variety of technologies, since most enterprises have a variety of technologies and languages, and more may come in the future. The choice of implementation should not be dictated by the design. Maybe that's a better way of putting it. Sure, objects and components have benefit. But thinking about services more abstractly can provide additional benefit. Eric ----- Original Message ---- From: Jerry Zhu <[EMAIL PROTECTED]> To: [email protected] Sent: Thursday, February 8, 2007 1:44:41 PM Subject: Re: [service-orientated-architecture] Booch on SOA & Architecture Eric, You said "things" maps to objects and "functions" map to services. Don't objects have data members and function members? So there are functions in objects and functions in services. You may say that functions in objects and function in services are different. I so I would like to know what is the different. I think that implementation of services w/o objects/components loses some key benefits - the very business value SOA provides at different level. The service level abstraction in your book describes objects are at the level below the level of service. Best Jerry --- Eric Newcomer <[EMAIL PROTECTED] com> wrote: > I do not think I said anything about objects being > "bad" for implementing services, nor would I say so. > They are a completely valid option. > > But an object is not a service, even though a > service can be implemented using one. And therefore > it's bad or any counterproductive to think of the > world in terms of "things" that maps to objects, > instead of as "functions" that map to services. > > A service is not a subset of an object, either, as > some would say. The concept of a service predates > the concept of an object and is more abstract. > > A good test is to ensure that a service design could > be implemented using an object, a message queue, a > procedure, stored procedure, database query, script, > etc. If the service design can only be implemented > using an object then the benefit of the abstraction > is lost. > > To me this is a conceptual problem, and a modeling > problem, not an implementation issue. People are so > used to thinking about software systems in terms of > objects that they often misunderstand services. > Some folks prefer to draw parallels but I prefer to > highlight differences since so many people tend to > equate the two. > > This is why UML and MDA are not well suited for Web > services, by the way, since their design center is > the class diagram. > > Eric > > > ----- Original Message ---- > From: Gregg Wonderly <[EMAIL PROTECTED]> > To: service-orientated- architecture@ yahoogroups. com > Sent: Thursday, February 8, 2007 12:53:42 AM > Subject: Re: [service-orientated -architecture] Booch > on SOA & Architecture > > Eric Newcomer wrote: > > Obviously someone who can't give up objects in > favor of services. > > Humm, does that mean that a service can never be an > object, but must be multiple > objects or multiple of something? I agree that all > "services" in an SOA may not > be software services, but for software based > services, what makes it bad for > them to be objects in implementation? > > Gregg Wonderly > > > > > > ____________ _________ _________ _________ _________ _________ _ > Get your own web address. > Have a HUGE year through Yahoo! Small Business. > http://smallbusines s.yahoo.com/ domains/? p=BESTDEAL ____________ _________ _________ _________ _________ _________ _ Get your own web address. Have a HUGE year through Yahoo! Small Business. http://smallbusines s.yahoo.com/ domains/? p=BESTDEAL ____________________________________________________________________________________ Yahoo! Music Unlimited Access over 1 million songs. http://music.yahoo.com/unlimited
