I also follow the WS-Commons mailing list and I've always wondered why they are using a separate XML Schema implementation :)
>From the little I know I can say that Xerces2/J has a pretty stable XML Schema implementation optimized for XML schema validation. Also I believe our implementation covers the XML Schema specs almost completely. And not to mention we are well on our way to supporting the XML Schema 1.1 spec :) Thanks, Hiranya Jayathilaka On Mon, Apr 6, 2009 at 8:59 AM, Michael Glavassevich <[email protected]>wrote: > Xerces has had its own XML Schema API [1][2] for years which has many > users. This API is implemented by Xerces-J, C++ and Perl, providing a > read-only view of the XML Schema component [3] model which is primarily > exposed through PSVI [4]. In Xerces-J the implementation is optimized for > schema validation. DOM is an intermediate representation in building it but > we throw it out at the end. Keeping it around would bloat memory usage and > doesn't fit into the programming model which is schema component centric > rather than schema document centric. > > I was aware that WS-Commons decided to develop its own API though I must > say I never understood why given all the choices which already existed > [1][5][6][7]. I just assumed that the community had its reasons, perhaps to > support some specific scenarios which don't fit well with the goals of these > other APIs. I wouldn't have guessed that it would have been due to ignorance > of their existence. Surely someone would have known about at least a few of > these before starting this WS-COMMONS project, right? > > Thanks. > > [1] http://www.w3.org/Submission/2004/SUBM-xmlschema-api-20040309/ > [2] http://xerces.apache.org/xerces2-j/javadocs/xs/index.html > [3] http://www.w3.org/TR/xmlschema-1/#concepts-data-model > [4] > http://xerces.apache.org/xerces2-j/javadocs/xs/org/apache/xerces/xs/ItemPSVI.html > [5] http://www.eclipse.org/modeling/mdt/?project=xsd#xsd > [6] http://xmlbeans.apache.org/docs/2.4.0/reference/index.html > [7] https://xsom.dev.java.net > > Michael Glavassevich > XML Parser Development > IBM Toronto Lab > E-mail: [email protected] > E-mail: [email protected] > > Benson Margulies <[email protected]> wrote on 04/05/2009 06:44:24 PM: > > > > Lawrence, > > > > Historically, that might have been the case or the intention, but > > there's nothing 'pull-y' about it today. If you feed it files, it > > builds dom and walks dom. If you feed it dom, it just walks dom. > > > > Now, I'm not an axis2 developer, I'm a cxf developer, but from > > inside the code I just can't see how it would be a problem. > > > > -benson > > > On Sun, Apr 5, 2009 at 6:22 PM, Lawrence Mandel <[email protected]> > wrote: > > > > Hi Benson, > > > > I may not be remembering correctly, but I thought that one of the > > reasons for developing XmlSchema in WS-COMMONS was to support a pull > > based model (Axiom). I completely agree that there should not be > > duplication of effort around these models at Apache. (Our collective > > time is better served solving other problems.) Do you foresee any > > issues (primarily with Axis2) with moving XmlSchema to a strictly > > DOM based model? Is this question even relevant? > > > > Thanks, > > > > Lawrence > > > > > From: > > > > Benson Margulies <[email protected]> > > > > To: > > > > [email protected] > > > > Cc: > > > > Daniel Kulp <[email protected]>, [email protected] > > > > Date: > > > > 04/05/2009 05:45 PM > > > > Subject: > > > > How many XML Schema libraries at ASF is too many XML Schema > Libraries? > > > > Sent by: > > > > [email protected] > > > > > > > > > Dear Xerces-J developers, > > > > At the moment, I'm the most active maintainer of Apache Xml Schema. > > This library, which lives inside the WS-COMMONS project, which lives > > inside the Web Services TLP, is a set of Java classes that form a > > data model for W3C XML Schema, together with code to walk DOM of > > schema documents and build the representation and visa versa. > > > > XmlSchema has no capability to validate a document against a schema. > > Typical applications, such as Apache CXF or Apache Axis, spend a > > fair amount of time converting back and forth between XmlSchema > > representation and the ordinary DOM for schema documents, if only to > > pass them into the SchemaFactory to tee up validation, or into some > > other library. > > > > While I haven't gone spelunking in the code of Xerces yet, the > > existence of the validation feature strikes me as strong > > circumstantial evidence the existence of some representation of schema. > > > > It strikes me that two Java class libraries for W3C XML Schema > > inside ASF is, prima facia, one too many. So, I'm sending this email > > to ask if the Xerces project has interest in working on exposing a > > documented API to the XML Schema data model. > > > > I was am more or less on the verge of putting a significant pulse of > > effort into modernization and performance enhancement of XmlSchema, > > and if the same effort could yield a more broadly useful result, I'd > > like to apply it there. > > > > I am imagining a scheme where the core representation is dom, using > > subclasses of DOM interfaces to supply convenience methods for safe > > and comprehensible access to the abstract data model. This could > > radically speed up code that needs to handle schema documents as DOM > > and also analyze and manipulate the abstract data model of the W3C > > Xml Schema. But, imagination aside, I think it would be good to > > focus energy on a shared solution. > > > > > > Regards, > > Benson Margulies > -- Thanks, Hiranya Jayathilaka I Blog Here: http://techfeast-hiranya.blogspot.com
