Here's a couple of thoughts on this: First, on the migration subject. Migration is a difficult issue, in this case complicated by the fact that users depend on generated artifacts. Saying that manual mapping of existing Java code to Schema interfaces is allowed doesn't do much in solving it. You still have to map 100 Java classes to their Schema counterparts and in more realistic scenarios, the number is 1000+. That's logic that you will have to maintain and update as time goes by, and why would you write this logic in an XML or text config file rather than writing it in Java, when writing logic is what Java is good at. I actually have first-hand experience with the problem of mapping existing Java classes to existing Schema classes and in the end it may be something to make the user feel more confortable, but not a solution to a real-world problem.
On the generic XML library, isn't XmlBeans is the best example of this? We support Java typed access, DOM, SAX, StAX, XmlCursor (it serves the same purpose as DOM, but much faster), Xpath/Xquery. We don't support everything you may think of, but what we do support is pretty well integrated. That gives the user the freedom and power to combine whatever tools are best without the penalty of having to convert between formats and lose data in the process. Now the trouble with making it general is that the integration will not be as seamless, since you need specific statically-bound methods to make it very usable (like a .getJDomNode() where you currently have .getDomNode() or JDOM-typed parameters to factory methods). To overcome that and to make the performance acceptable you would have to bake any new model in the XmlBeans code directly. And even with "just" the models we currently support, you get penalized on performance. But, let's take heart from the fact that Java itself was criticized for performance reasons at the beginning, but users loved the simplicity and power that it offered them and eventually the performance got better and better until here we are today ;-) Sorry for the long post, Radu -----Original Message----- From: Jean-Christophe Pazzaglia [mailto:[EMAIL PROTECTED] Sent: Wednesday, October 26, 2005 1:31 AM To: [email protected] Subject: Re: Migrating from castor to XMLBeans Hi Dennis, Very good analysis of the strengths and weaknesses of frameworks that I fully support, (if you look carefully my post you'll notice an interrogation mark near SAX) [can I integrate it in my lectures :) ?] However, I do believe that a library can cover the spectrum from generic document model (DOM) to specific data binding (java or xml centric). Upto a certain extent Castor was able to use both approach, however since it does not keep the original document (correct me if I am wrong) which implied that it was impossible to add DOM features and quite difficult to add xpath alike accessor. (which motivated my switch to XMLBeans) > AFAIK, it also requires developers to use classes generated from > schema for the data binding operation, making it one of the few data > binding frameworks that offers no support whatsoever for working with > ordinary Java classes. Maybe someone can imagine a way to integrate standard classes into an XMLBeans framework, this will probably imply to automatically generate a schema from the classes (should not be too difficult) and to provide on demand the XML document. Specific annotations or interfaces may enable to modify the generic binding. Ideally, the document should be tagged to keep track that, in this case, the main data representation is in java and that any modification of the document should be done in the object too (which may be more problematic). The questions are : - is it worst the job ? - will it not be more difficult for the developer ? - will the performance overhead be not too prohibitive ? Sorry for the noise :) jc side note : how can you agree with someone who is willing to replace reflection with compiled code :P ? Dennis Sosnoski wrote: > Hi jc, > > This seems a lot like saying "it's really annoying to have to use > cars, boats, and planes to get places - why don't people just build a > single device that replaces all of these?" :-) > > There are a lot of overlaps between the different frameworks for > working with XML in Java, but also a lot of differences. At the parser > level, SAX and StAX are fundamentally different. The document model > differences are more cosmetic - DOM, JDOM, dom4j, XOM, etc. are all > basically just variations of a tree API. When you get to data binding, > the differences are again very real. > > I see mapped binding approachs as being fundamentally Java-centric, > where you add the XML data binding in an aspect-oriented fashion to > your existing Java classes. Castor used this approach originally, and > still supports it, but JiBX offers greater flexibility (as well as > much better performance than Castor). JAXB 2.0 also offers limited > support for mapped bindings, using annotations in code. > > The other type of approach is code generation from schema, which is > inherently schema-centric. Most data binding frameworks support this > approach, though with different limitations on the schema constructs > supported. > > XMLBeans really crosses the framework classes, in that it combines a > document model with data binding (perhaps more accurately, it builds a > data binding facade on a document model architecture). This gives it > unique strengths, especially for developers who need to access the > full structure of the XML but also want to access typed data values > through Java objects. It also makes for some weaknesses - XMLBeans > generally uses a lot more memory than conventional data binding > frameworks, and operates considerably slower (especially when reading > or writing data through the data bound objects). AFAIK, it also > requires developers to use classes generated from schema for the data > binding operation, making it one of the few data binding frameworks > that offers no support whatsoever for working with ordinary Java classes. > > - Dennis > > Jean-Christophe Pazzaglia wrote: > >> Hi, >> >> I am involved on XML Programming since 98 >> and back in 99 (my first lecture on the topic) >> I was already wondering why someone was not >> able to provide a common framework to 'program' XML. >> >> 6 years later it seems that we still have to use different libraries >> for different needs, I moved to XMLBeans from Castor because I >> thought that XMLBean was more promising (notably the integration with >> xpath and that it keeps the original document, >> while probably Castor is better as doing customized and schemaless >> mapping) >> and I am still fighting integrating code using DOM with my XMLBean >> library, so I am simply wondering : >> >> is it not possible to have one framework (let's say XMLBean++) able >> to provide the solution (e.g integrating JAX*) , providing handy >> switch between the different programming model (so I can use it as a >> SAX(?)/DOM/JDOM provider and switch idiom when needed [I know it may >> not be so simple >> ...]) >> >> jc >> >> >> >> from >> >> >> >>> Your best choice is probably JiBX (http://www.jibx.org). JiBX is the >>> fastest XML data binding framework (https://bindmark.dev.java.net/), >>> and lets you work with existing classes. You can use the binding >>> generator from the tools subproject to generate a default binding >>> from your existing classes, then customize that if necessary to get >>> exactly what you want. >>> >>> If you have questions about JiBX, join up on the JiBX users mailing >>> list (http://sourceforge.net/mail/?group_id=69358) and send the >>> questions there. >>> >>> - Dennis >>> >>> Zhong ZHENG wrote: >>> >>> >>>> Hi, >>>> >>>> Thanks for your advice. But the format of my XML file is already >>>> defined, although i did not create schemas. If necessary, i may >>>> create schema for my XML. But i do not want to use >>>> XMLBeans-generated classes. So is it possible to do the data >>>> binding by using my own java beans? >>>> >>>> Regards. >>>> >>>> On 10/22/05, *Giedrius Trumpickas* <[EMAIL PROTECTED] >>>> <mailto:[EMAIL PROTECTED]>> wrote: >>>> >>>> If you don't have schemas defined for your XML and have already >>>> existing beans use: >>>> >>>> http://xstream.codehaus.org/ >>>> >>>> Giedrius >>>> >>>> >>>> >>>> -- >>>> >>>> ZHENG Zhong >>>> >>>> 1 Avenue Alphand >>>> 75116 Paris, France >>>> +33 6 76 80 45 90 >>>> >>> >>> -------------------------------------------------------------------- >>> - >>> To unsubscribe, e-mail: [EMAIL PROTECTED] >>> For additional commands, e-mail: [EMAIL PROTECTED] >>> >>> >> >> >> >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > -- Jean-Christophe Pazzaglia, PhD <[EMAIL PROTECTED]> Network Security Team Tel: (+33) 4-93-00-26-78 PGP Key available : http://www.eurecom.fr/~pazzagli/publickey.pgp -- Institut Eurécom - Office 029 http://www.eurecom.fr/ 2229 Route des Crêtes BP 193 06904 Sophia Antipolis, France Fax: (+33) 4-93-00-26-27 --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
