Hi Sanjaya, The ultimate goal is to improve the usefulness of XInclude in Xerces. What you can do with the existing XPointer support is very limited and would be greatly improved if it supported a subset of XPath.
For example: Input: <?xml version="1.0"?> <root xmlns:xi="http://www.w3.org/2001/XInclude";> <xi:include href="groups.xml" xpointer="xpointer(groups/group [...@name='A2'])"/> </root> groups.xml: <?xml version="1.0"?> <groups> <group name="A1"> ... </group> <group name="A2"> ... </group> <group name="A3"> ... </group> ... </groups> Result: <?xml version="1.0"?> <root xmlns:xi="http://www.w3.org/2001/XInclude";> <group name="A2"> ... </group> </root> The first document could have to be written as: <?xml version="1.0" ?> <root xmlns:xi="http://www.w3.org/2001/XInclude";> <xi:include href="groups.xml" xpointer="element(/1/2)"/> </root> with the current version of Xerces though this requires that you always know the position of the elements that you want to select from the included document and would have to update the xpointer if it changes. Regarding the last() function, you can't compute it without looking ahead so wouldn't be one that we could support for XInclude since we need to make a decision on the startElement() event on whether it's included or not in the result. Thanks. Michael Glavassevich XML Parser Development IBM Toronto Lab E-mail: [email protected] E-mail: [email protected] Sanjaya Liyanage <[email protected]> wrote on 03/21/2010 06:31:34 AM: > Hai Michael, > What is the extend that xerces wants to reach through this > project?I mean if you can give me an idea about the ultimate goal of > this project bringing out an example it would be great for me to have > a proper approach to the project. > Thanks in advance. > Sanjaya Liyanage > > On Fri, Mar 19, 2010 at 12:45 AM, Sanjaya Liyanage > <[email protected]> wrote: > > Hi Michael, > > I went through the predicate functions like > > position(),last(),nodeName(number) and also had some hands on lab > > experience and it's amazing that the paths like SomeNode(position()<3 > > and position()>(last()-1)]) are also supported by the current > > xpath.But it is not supported to statements like (last() /2).I feel > > that this may be due to the ability of last() to return an odd > > number.But it is not even support for last()%2.Do you know any other > > way I can access these divisions and modulous divisions?. > > Thank you. > > Sanjaya Liyanage > > > > On Thu, Mar 18, 2010 at 10:21 PM, Sanjaya Liyanage > <[email protected]> wrote: > >> Hi Michael, > >> Thank you very much for directing me the proper way to gain > >> some good back ground knowledge even though you are so busy these > >> days.I'll follow the points you mentioned. > >> Thank you > >> Sanjaya Liyanage > >> > >> On Thu, Mar 18, 2010 at 5:59 PM, Michael Glavassevich > >> <[email protected]> wrote: > >>> Hi Sanjaya, > >>> > >>> I didn't have any specific functions in mind. I was thinking of an XPath > >>> subset such as: > >>> > >>> * XPath axes: child, descendant, descendant-or-self, self and associated > >>> abbreviations. > >>> * node() test and associated abbreviation (*) > >>> * predicate functions: position() and associated abbreviation > ([number]) and > >>> abbreviated attribute specifier (@) > >>> * predicate operators: equality, inequality, "and" and "or". > >>> * predicate number and string literals. > >>> > >>> This is one that was proposed when we were initially working on > XInclude. I > >>> think it would be a good start and possibly enough to keep you > busy over the > >>> summer, though you're certainly free to propose something else (e.g. > >>> including some functions you're interested in). > >>> > >>> Thanks. > >>> > >>> Michael Glavassevich > >>> XML Parser Development > >>> IBM Toronto Lab > >>> E-mail: [email protected] > >>> E-mail: [email protected] > >>> > >>> Sanjaya Liyanage <[email protected]> wrote on 03/12/2010 05:41:14 AM: > >>> > >>>> Hi Michael, > >>>> I think now I have got some decent knowledge on xpath and now > >>>> I'm going through Xpointer and Xlink.But I skipped going through the > >>>> xpath functions as there are plenty of them.Can you tell me whether > >>>> should I go through all of the xpath functions or can you specify some > >>>> vital functions which can be helpful me? > >>>> Thank you. > >>>> Sanjaya Liyanage > >>>> > >>>> On Tue, Mar 9, 2010 at 9:32 PM, Sanjaya Liyanage <[email protected]> > >>>> wrote: > >>>> > Hi Michael, > >>>> > Thank you very much for your clarification and it gave me a > >>>> > decent > >>>> > idea about what i looking for. > >>>> > regards > >>>> > Sanjaya. > >>>> > > >>>> > On Tue, Mar 9, 2010 at 7:00 PM, Michael Glavassevich > >>>> > <[email protected]> > >>>> > wrote: > >>>> >> > >>>> >> Hi Sanjaya, > >>>> >> > >>>> >> "//" [1] is a short form for the descendant or self axis, meaning it > >>>> >> selects any descendants which match the following part of the > >>>> expression not > >>>> >> just the immediate children. It doesn't make a difference for the > >>>> >> example > >>>> >> you posted because every "book" is an immediate child of > >>>> "bookstore", but if > >>>> >> the document had been: > >>>> >> > >>>> >> <bookstore> > >>>> >> <someotherelement> > >>>> >> > >>>> >> <book> > >>>> >> <title lang="eng">Harry Potter</title> > >>>> >> <price>29.99</price> > >>>> >> </book> > >>>> >> </someotherelement> > >>>> >> </bookstore> > >>>> >> > >>>> >> only the bookstore//book expression would select the "book" element. > >>>> >> The > >>>> >> bookstore/book expression would not select anything in this document > >>>> >> since > >>>> >> there is no "book" child immediately under "bookstore". > >>>> >> > >>>> >> Hope that makes sense. > >>>> >> > >>>> >> If you have more general questions about XPath the XSL > Mulberry mailing > >>>> >> list [2] is a very good resource and would encourage you to join > >>>> it and also > >>>> >> have a look in its archives. > >>>> >> > >>>> >> Thanks. > >>>> >> > >>>> >> [1] > >>>> >> > >>>> >> http://www.zvon.org/xxl/XSLTreference/Output/ > axis_descendant-or-self.html > >>>> >> [2] http://www.mulberrytech.com/xsl/xsl-list/ > >>>> >> > >>>> >> Michael Glavassevich > >>>> >> XML Parser Development > >>>> >> IBM Toronto Lab > >>>> >> E-mail: [email protected] > >>>> >> E-mail: [email protected] > >>>> >> > >>>> >> Sanjaya Liyanage <[email protected]> wrote on 03/09/2010 > 04:24:43 AM: > >>>> >> > >>>> >> > Hi Michael, > >>>> >> > First of all thank you very much for your reply and it > >>>> >> > really encouraged me.I already began to go through the Xpath as > >>>> >> > Xpointer is also built on xpath expressions.I refer w3school site( > >>>> >> > http://www.w3schools.com/xpath/default.asp) for gaining knowledge on > >>>> >> > xpath.But I came across a doubt about the expressions ' / ' and ' > >>>> >> > // ' .What is the difference between these two expressions. > >>>> >> > The example they use is, > >>>> >> > <?xml version="1.0" encoding="ISO-8859-1"?> > >>>> >> > > >>>> >> > <bookstore> > >>>> >> > > >>>> >> > <book> > >>>> >> > <title lang="eng">Harry Potter</title> > >>>> >> > <price>29.99</price> > >>>> >> > </book> > >>>> >> > > >>>> >> > <book> > >>>> >> > <title lang="eng">Learning XML</title> > >>>> >> > <price>39.95</price> > >>>> >> > </book> > >>>> >> > > >>>> >> > </bookstore> > >>>> >> > > >>>> >> > As they mention > >>>> >> > > >>>> >> > expression Result > >>>> >> > > >>>> >> > bookstore/book > >>>> >> > > >>>> >> > Selects all book elements that are children of bookstore > >>>> >> > > >>>> >> > bookstore//book > >>>> >> > > >>>> >> > Selects all book elements that are descendant of the bookstore > >>>> >> > element, no matter where they are under the bookstore element > >>>> >> > > >>>> >> > Can you please give me the idea? > >>>> >> > > >>>> >> > thank you > >>>> >> > sanjaya > >>>> >> > > >>>> >> > On Tue, Mar 9, 2010 at 10:20 AM, Michael Glavassevich > >>>> >> > <[email protected] > >>>> >> > > wrote: > >>>> >> > Hi Sanjaya, > >>>> >> > > >>>> >> > Welcome to the mailing list and thanks for your interest in Xerces. > >>>> >> > > >>>> >> > The XPointer project on the idea list from last year is still open > >>>> >> > if you'd like to work on it. Aside from becoming familiar with the > >>>> >> > relevant specifications I'd recommend taking a look at the existing > >>>> >> > XInclude / XPointer implementation in Xerces as well as the XPath > >>>> >> > support that is already in place. > >>>> >> > > >>>> >> > Feel free to ask questions here if you have any. > >>>> >> > > >>>> >> > Thanks. > >>>> >> > > >>>> >> > Michael Glavassevich > >>>> >> > XML Parser Development > >>>> >> > IBM Toronto Lab > >>>> >> > E-mail: [email protected] > >>>> >> > E-mail: [email protected] > >>>> >> > > >>>> >> > Sanjaya Liyanage <[email protected]> wrote on 03/03/2010 11:33:38 > >>>> >> > PM: > >>>> >> > > >>>> >> > > >>>> >> > > Hi, > >>>> >> > > I am so much interested about the project "Implement a > >>>> >> > > streamable subset of the XPointer xpointer() scheme for XInclude" > >>>> >> > > with subject id "xerces-xinclude-xpointer-enhancements" @ Gsoc > >>>> >> > > 2009 idea list.I had a determination to develop a xml > parser by my > >>>> >> > > own when I use libxml for one of my projects(When I > tried to create > >>>> >> > > a plug-in to Anjuta) and I think this Gsoc project will be a great > >>>> >> > > chance to gain a knowledge which may be helpful to achieve my > >>>> >> > > determination one day. > >>>> >> > > In these days I am paying my > >>>> >> > > attention to XPointer Framework and XPointer element() to have an > >>>> >> > > idea about how the Xinclude requirement are satisfied present > >>>> >> > > time.I hope this project idea will remain for Gsoc 2010 and please > >>>> >> > > let me know if you know anything that can be helpful me > to create a > >>>> >> > > proper background knowledge before the projects are really getting > >>>> >> > > started.Thank you all. > >>>> >> > > > >>>> >> > > regards > >>>> >> > > Sanjaya Liyanage. > >> > >
