Eric,
many thanks for throwing light for me in this issue. Most of times, the more difficult responses to find, are not how are the things done, but rather why are not they done in different way. Most of reports, software comments, ... says what they do, but not why they do not apply a different approach. As you say, a nice issue to think about. Best regards, Adolfo. >From: "Schneider, Eric" <[EMAIL PROTECTED]> >Reply-To: "Struts Users Mailing List" <[EMAIL PROTECTED]> >To: "'Struts Users Mailing List'" <[EMAIL PROTECTED]> >Subject: RE: Object Relational Bridge is great ? A Basic Problem >Date: Mon, 8 Jul 2002 11:50:09 -0400 > >Adolfo, > >I understand what you are getting at, but there is a reason why this >framework doesn't exist. It's because it is an extremely difficult >problem. > >I have used a couple of O/R frameworks that come close to doing what you >describe. Instead of creating concrete classes with accessors for every >entity they use a generic class that allows you to access attributes by >calling getObjectForKey() and setObjectForKey(). But, still, this type of >framework requires an additional configuration layer of property files that >contain metadata information pertaining to database. > >Think of all the things this ER configuration layer must keep track of: >-entity to table name mapping >-object attribute to table column mapping (types, precision, is attribute >required, etc.) >-relationship descriptions (to-one, to-many, optionality, cardinality, >cascading deletes, etc.) > >On top of that, add business rules into the mix and it gets complex really >fast. Think of all the different ways you need to validate information. >Is >the validation different for a property based on whether you are inserting, >updating, or deleting? Where is this validation suppose to go? > >When you dig a bit deeper you quickly find out there is nothing 'Basic' >about good object relational frameworks. > >Food for thought. > >e. > > > -----Original Message----- > > From: Adolfo Miguelez [mailto:[EMAIL PROTECTED]] > > Sent: Monday, July 08, 2002 10:42 AM > > To: [EMAIL PROTECTED] > > Subject: RE: Object Relational Bridge is great ? A Basic Problem > > > > > > > > Thanks Eric, > > > > I will have it a look. Looks like interesting. > > > > However, a question more, for you or whoever. I would like to > > hear someone > > agreeing my suspicions that for most of O/R mapping > > frameworks, we need to > > create the object classes that map database tables by > > compiling code or > > using ant tasks. None (do not know Cayenne yet), is able to > > do for itself. > > > > I did get any feedback sharing my point and I wonder if I am missing > > something. > > > > Regards and thanks anyway, > > > > Adolfo > > > > > > > > >From: "Schneider, Eric" <[EMAIL PROTECTED]> > > >To: "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]> > > >Subject: RE: Object Relational Bridge is great ? A Basic Problem > > >Date: Mon, 8 Jul 2002 06:55:44 -0600 > > > > > >Adolfo, > > > > > >Have a look at this....maybe it better suits your needs. > > It's in alpha, > > >but > > >don't let that fool you. It's more mature than most OR > > tools I've looked > > >at. > > > > > >http://objectstyle.org/cayenne > > > > > >Eric > > > > > > > -----Original Message----- > > > > From: Adolfo Miguelez [mailto:[EMAIL PROTECTED]] > > > > Sent: Friday, July 05, 2002 5:50 PM > > > > To: [EMAIL PROTECTED] > > > > Subject: Re: Object Relational Bridge is great ? A Basic Problem > > > > > > > > > > > > > > > > Hi, > > > > > > > > as a newbie in O/R mapping tools, APIs and frameworks I find > > > > the following > > > > issue. All of the frameworks that I have browsed lacks from a > > > > basic problem: > > > > The classes that maps the corresponding tables in the > > > > database must be > > > > manually generated, either by hand (e.g. OJB) or by building > > > > the code (e.g. > > > > Jakarta Torque). > > > > > > > > This becomes a pain since it difficults to make an > > > > application that could > > > > "learn" for itself a data model and create its own classes. > > > > No way, AFAIK, > > > > for implementing general mechanism. > > > > > > > > I know about BCEL project, which is able to compile classes > > > > in runtime, and > > > > it could be really helpful to integrate with the previous > > > > ones and get > > > > automathic mechanims, but I do not any framework that take > > > > advantage of > > > > BCEL. > > > > > > > > The only way that I have seen to do something similar, is the > > > > mini-project > > > > SIMPER (Struts resources page), which is able to work out > > dynabeans > > > > (actually they are hashmaps in their guts), following a > > > > database schema, for > > > > it self. For me it has the problem that uses Servlets 2.3 > > > > filters and I am > > > > working with Servlets 2.2 specs. > > > > > > > > I just want to request your opinion or knowledge about a > > > > framework that can > > > > implement itself such a classes, or a framework which > > classes are not > > > > actually classes but hashmaps or something like that.... or > > > > even some one > > > > taking advantage of BCEL or analogous mechanism. I know is a > > > > difficult > > > > question, supposing that I am not mixing any concept up. > > > > > > > > :-) > > > > > > > > Thanks in advance, > > > > > > > > Adolfo > > > > > > > > >From: Adam Hardy <[EMAIL PROTECTED]> > > > > >Reply-To: "Struts Users Mailing List" > > > > <[EMAIL PROTECTED]> > > > > >To: Struts Users Mailing List <[EMAIL PROTECTED]> > > > > >Subject: Re: Object Relational Bridge is great ! > > > > >Date: Fri, 05 Jul 2002 18:15:45 +0200 > > > > > > > > > >Hi Fabrice, > > > > >did you check out JDO? If so, why didn't you prefer it? > > > > > > > > > > > > > > > > > > > >fabrice dewasmes wrote: > > > > >>Hi, > > > > >> > > > > >>no problem this time but i'd like to applause chuck > > > > Cavaness with both > > > > >>hands > > > > >>for the public review of his struts book. Chuck, you're > > > > clairvoyant : > > > > >>using > > > > >>Object relational bridge is a great idea. we've hesitated > > > > between torque, > > > > >>castor, and OJB and it appears that OJB has a really > > > > powerful API and > > > > >>allows > > > > >>all kind of relational mappings (1:1, 1:n, m:n, > > > > inheritance, polymorphism, > > > > >>...) it saves a lot of time and i think this is many more > > > > powerful than > > > > >>EJBs. > > > > >> > > > > >>I definitely recommend this persistence framework to any > > > > people beginning > > > > >>a > > > > >>struts project (or even non struts project) > > > > >> > > > > >>Fabrice > > > > >> > > > > > > > > > > > > > > > > > > > >-- > > > > >To unsubscribe, e-mail: > > > > ><mailto:[EMAIL PROTECTED]> > > > > >For additional commands, e-mail: > > > > ><mailto:[EMAIL PROTECTED]> > > > > > > > > > > > > > > > > > _________________________________________________________________ > > > > MSN Photos is the easiest way to share and print your photos: > > > > http://photos.msn.com/support/worldwide.aspx > > > > > > > > > > > > -- > > > > To unsubscribe, e-mail: > > > > <mailto:struts-user-> [EMAIL PROTECTED]> > > > > For > > > > additional commands, > > > > e-mail: <mailto:[EMAIL PROTECTED]> > > > > > > > > > > > > >************************************************************* > > ********* > > >This message, including any attachments, contains > > confidential information > > >intended for a specific individual and purpose, and is > > protected by law. > > >If you are not the intended recipient, please contact sender > > immediately by > > >reply e-mail and destroy all copies. 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