Peter Hu

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since Apr 15, 2005
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Recent posts by Peter Hu

For condition branchings, sometimes it can get very complex. Like the conditions may have haierachy structure that involves multiple objects. I just use a combination of possible values as keys -

obj1-value1 + "|" + obj2-value1
obj1-value1 + "|" + obj2-value2
obj1-value1 + "|" + obj2-value3
obj1-value2 + "|" + obj2-value1
obj1-value2 + "|" + obj2-value2
obj1-value3 + "|" + obj2-value3
....
[ July 05, 2008: Message edited by: Peter Hu ]
It really depends on how you want to do the abstraction. You can even model the computer that has many parts - a CPU, memory chips, ... These parts can be sold as single items as well.
[ July 05, 2008: Message edited by: Peter Hu ]
Simply put, a Session Facade provides the client with a high level application service interface; while Business Delegate gears towards reducing the compexity of accessing a business function/component. Both of them can create a high level function thats interacts with multiple business objects to simplify the calling.

Both of them are designed to reduce the coupling between the client and the business components.

Client -> BDs -> BCs(distributed)

Client -> SF -> BCs(destributed or local)

Client -> SF -> BDs-> BCs(destributed or local)
--------------> BCs(destributed or local)
[ June 29, 2008: Message edited by: Peter Hu ]
Does IBM WSAD support DIME attachment? If it does, where can I find documentation on it?
14 years ago
I want to learn OOAD. If someone comes cross with a well-designed Java open source project, following good OO design principles with well-designed and balanced classes, applying proper design patterns and practicing OO design heuristics, please make a recommendation. I'll appreciate it.
From the structure perspect, I don't see much differency between them. They just describe similar things in different contexts. In J2EE, business delegate does sound better than facade.
You have to understand this directive in the correct context. It doesn't use it in the context of the servlet container but the developer. If you set it to true, it means you - the developer - understand the burden is on yourself to quarentee to write it thread safe; if it's false, that means you don't have to write thread safe code, the container does it for you.

Also the implemntation is up to the servelt container's vendor. STM is not dictated here. You can synchronize the incoming requests instead.
14 years ago
JSP
<jsp:getProperty> is an method call that executes on a java bean. <jsp:useBean> creates an object. It needs to know where to store this object - defining its scope. Ideally <jsp:getProperty> should have a scope control, say only searches in certain scope. But it doesn't.
14 years ago
JSP
Your issue is related to the scope of the objects. The page scope is just within the doGet or doPost method. Therefore pageContext can be accessed only from the page, i.e. the doGet or doPost method. When you declare a var using <@! > tag, it creates it in object scope that is outer doGet or doPost. An object scope var can not reference a local var inside a method.



[ May 26, 2006: Message edited by: Paul HG ]
[ May 26, 2006: Message edited by: Paul HG ]
14 years ago
JSP
The jspInit method is provided by the jsp convention. It's not the equivalent of the servlet init method, rather it provides the similar opportunety to do your initialization work. The servlet's init method still exists and lives well inside jsp. The reason jsp doesn't inherit directly, instead offers the jspInit, is that it wants to make sure the execution of init() is proper without being diverted accidentally by non-experienced programmers. If you want the config, override the init method.
14 years ago
JSP
Program Development in Java: Abstraction, Specification, and Object-Oriented Design. Addison Wesley, 2001 by Barbara Liskov, first female awarded a PHD in Computer science in USA. Remember one of the OO principles - LSP, she and Jeanette Wing first wrote in a paper.

But it seems not many people know her book, is it a good book? Or it just can't catch anybody's attention? Amazon has very high rating on this book, by just a few viewers through.
I am doing a project which front end needs to display different types of documents using applets from different vendors. All the applets use different set of parameters. Currently I use a Properties object to pass the parameters into an applet tag renderer for each type of applet. Is there any better way to encapsulate the difference between these applet parameters?

Thank you all for your suggestions and opinions.
If there is a business requirement change to an existing process, which results in an activity and/or other charts to be changed accordingly, is it possible to present both the old and new requirements on the same chart, and people can easily see where the changes are? How is this kind of changes(change of an existing process, not adding new requirements) normally present?
Does it need at least J2EE version 1.3 to host a WebService in WebSpehere application server?
15 years ago