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From Robert McIntosh <rob...@bull-enterprises.com>
Subject Re: [OT]: Struts, Web Development, J2EE, and what is too much?
Date Tue, 11 Mar 2003 23:08:18 GMT


Aaron O'Hara wrote:

>Thanks for you detailed reply.  Is it a safe to say that if all the
>following are true, EJBs may not be a wise choice:
>
>-- I want to provide DB Vendor specific queries that are optimized to
>take advantage of each vendor
>
>-- the application has only 1 front end, servlets/jsp
>
>-- There is only one "data store" and transactions do not span more than
>1.
>
>-- entity model is far different than object model
>
>I find that in my design, the object model differs greatly from
>database.  From an application's perspective, you design it so that it
>is usable and uses appropriate modeling based off of the requirements of
>the application.  For example, if you stored all email addresses in a
>separate table and had a contact table, you may decided that your object
>model will have an emailAddress field and not a foreign key reference to
>the record in an EmailAddress object.
>
I find this to occur in almost all applications I end up developing. 
Especially when the database already exists. Joining across tables is 
not something entity beans handle well... They also don't support stored 
procedures, if you are using them.

>
>>>From a database design point of view, you may interpret the requirements
>and design the database based on a number of different factors, such as
>normalization, performance, etc.  An application that is report-heavy
>may benefit from de-normalized design whereas an input-heavy may benefit
>from a highly normalized design.  Based on that line of thinking, one
>may decide to put all email addresses in a separate table.  (This is not
>a great example, since most contacts will have a unique address, but
>hopefully my point is still coming across).
>
>Given the above, does it make sense that EJBs are not necessary and I
>would not receive a great benefit from them?
>
I would say yes in your situation.

- Robert

>
>Thanks,
>
>Aaron
>
>-----Original Message-----
>From: Robert McIntosh [mailto:robert@bull-enterprises.com] 
>Sent: Tuesday, March 11, 2003 8:39 AM
>To: Struts Users Mailing List
>Subject: Re: [OT]: Struts, Web Development, J2EE, and what is too much?
>
>Tony made some good points, and my take is that from your requirements, 
>you may not need EJBs. However, if you layered your app sufficiently, 
>then if you end up needing them later on, it shouldn't be too much of a 
>problem. Of course I am assuming you are referring to Entity beans in 
>this case...
>
>As for when to use EJBs, what I have always recommended to our clients 
>is that EJBs are good for large scale applications that run on clustered
>
>machines and require transactions at the entity bean level. The 
>transactions are good if you have multiple apps and clients that are 
>modifying the same data. If your app is largely read only, it is the 
>only one interacting with the data and you aren't worried about 
>concurrent modifcation, then you probably don't need entity beans. Yes, 
>most app servers can cache and mark entity beans as read-only or mostly 
>read-only for performance, but there are other ways of doing the same
>thing.
>
>Another thing to consider is how your object model is designed. If you 
>have lots of inheritance, entity beans aren't going to fit you well. 
>Same can be said if you have complex query requirements (joins, 
>relationships that the object model doesn't support, etc.).
>
>Then again, in some cases as Nash pointed out, EJBs can be simplier from
>
>the perspective that any good app server can build the database for you 
>and with tools like XDoclet, you don't have to write deployment 
>descriptors and you don't have to maintain (i.e. code) the interfaces 
>for home, remote and local.
>
>- Robert
>
>Aaron O'Hara wrote:
>
>  
>
>>I know this question has probably been asked before, and that biased
>>publications have had their opinions on it, but I wanted to get some
>>feedback regarding some "real user experience" regarding the use of EJB
>>in a web application used along with Struts.
>>
>>I am creating a web application and I have decided to use struts.  The
>>application needs to be high performance, uses a single database (so it
>>doesn't have heterogeneous transactional db requirements).  I have
>>designed the application in layers, and it will only have a web
>>interface.  It's starting small, but will grow to have many functions.
>>Even though I'm confident that I need not invest in EJB's, I don't want
>>to develop the application to find out I should have used them (hence
>>why I'm creating this post).
>>
>>In what scenarios have people found the use of EJB beneficial?  When
>>have they been overkill?  Does struts integrate smoothly with EJBs?
>>
>>My fear is that I'll make the application overly complex by
>>    
>>
>implementing
>  
>
>>EJBs, but I'd like to hear from people with experience building large
>>web-only projects with struts.
>>
>>Thanks,
>>
>>Aaron
>>
>>
>>
>>
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>>
>
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