Hi All, I am just trying to get the discussion open for XQuery DAS.
In the path of building XQuery DAS implementation, it will be helpful to have code structure which can support different XQuery Implementations and not stick to one. I am trying to use DB2 Express's XQuery support as its a freeware. (XQEngine has licensing issues, ) XQuery DAS uses Service Provider framework to invoke required service flavour of DAS, like XQuery/LDAP.(Thanks to Luciano, his sandbox has some api, impl separation) Further, we can consider different XQuery implementations like DB2 Express, Saxon,.... The Service Provider framework similar to above can be used here too, to customize the DAS instance for a particular XQuery Impl. Also, we need to consider the fact that connection to data source can be - database connection, file system connection,....and keep the api module generic enough to accomodate that. I am changing the das-api a bit around that. Attaching a brief class diagram. Please give comments, suggestions. Regards, Amita On 6/21/07, ant elder <[EMAIL PROTECTED]> wrote:
Unfortunately it looks like XQEngine is GPL so unusable, we can't even have code using it in SVN. The only alternative i can think of is Saxon, maybe others know of something else? ...ant On 6/21/07, Amita Vadhavkar <[EMAIL PROTECTED]> wrote: > > Hi, > Need some help marked with #. > > In the implementation of XQuery DAS, I am trying to start simple and then > gather requirements and features on the way and keep building. > > #For the first attempt, I am trying with sourceforge's XQEngine as the > XQuery engine, as it has no license restrictions. Has anybody any comment > about which implementation is better/worse? > > I want to create JIRA for XQuery DAS to attach first patch on the top of > code available in > https://svn.apache.org/repos/asf/incubator/tuscany/sandbox/lresende/das. > #Help! Need somebody to create a new Component - Java DAS XQuery. > > https://svn.apache.org/repos/asf/incubator/tuscany/sandbox/lresende/dashas > a clear separation of api vs. impelmentation. > > In the first patch, I am trying to implement > org.apache.tuscany.dasinterfaces from tuscany-das-api into > tuscany-das-xquery and also using > ServiceProvider framework to invoke xquery implementation. > > The code is very basic and working for single directory/single xml file 's > xquery expression > evaluation and there is nothing done for building a very basic DataObject > (in-progress) > The beginning of the mail thread has many features, here the features to > be > implemented in the order or importance, please add/comments to it. > > **************************************************************************************** > In the first attempt only xml files are considered and not databases > supporting XQuery. > As the development progresses - will attach a detailed design doc instead > of > having large mails - for easy review. > > Features List > 1) support connection to FileSystem (no authentication considered, only > mapped drive and directory) > 2) support xquery expessions as Command (using XQEngine to get result) > 3) mapping between result of xquery Command to DataObject (XQEngine can > emit > the xml , form a DataObject using XMLHelper) > 4) CRUD support - involves mapping from DataObject to xml document, change > summary to be added to file > 5) FLWOR expression as Command > 6) JOIN operation (use multiple files) > > Test Cases List > Ideally will have > 1 test case for each feature > > **************************************************************************************** > Hoping to make XQuery DAS useful to the community as an alternative to > other > DAS flavours. > > Regards, > Amita > > > On 6/15/07, Amita Vadhavkar <[EMAIL PROTECTED]> wrote: > > > > Hi All, > > After a while on RDB DAS beta1 , I am trying to do more on XQuery DAS. > > > > Tried to check different XQuery implementations available, below is > > summary: > > > > http://www.axyana.com///products.html Quizx/open - open source > > Quizx/db(XQuest) - not open source > > > > http://www.gnu.org/software/qexo/ - license? - kawa > > it compiles XQuery expressions and programs to Java bytecodes , this > does > > not have > > API to be used, so not of much use > > > > http://www.oracle.com/technology/sample_code/tech/xml/xmldb/jxqi.html- > > license will be a problem > > > > ***http://dsd.lbl.gov/nux/api/index.html - > > http://dsd.lbl.gov/nux/license.html > > has good set of APIs. I am not sure if the license poses some > restrictions > > on use. > > Looks like this will be a good choice to give first attempt for XQuery > > DAS. > > Any advise? > > > > http://saxon.sourceforge.net/ - only SAXON-B is fee and SAXON-SA is > > commercial,So may not be a good choice > > > > I am trying to start based on > > https://svn.apache.org/repos/asf/incubator/tuscany/sandbox/lresende/das/ > > This uses Service Provider API to separate different DAS > implementations. > > There is > > http://www.mail-archive.com/tuscany-dev@ws.apache.org/msg14428.htmlthread > > to discuss the high level approach to provide this. Please add your > comments > > there for refactoring approach. > > > > We can use the current mail thread for XQuery DAS specific comments. > Also, > > I will use > > a new page on > http://cwiki.apache.org/confluence/display/TUSCANYWIKI/Home > > > > to track detailed status for XQuery DAS. I will make sure not to link > this > > page > > to any other page, so as not to mess up with ongoing release. > > > > Regards, > > Amita > > > > > > On 4/4/07, Luciano Resende <[EMAIL PROTECTED]> wrote: > > > > > > Hi Amita > > > > > > Related to the features, I think it's fine to start simple and get > > > improvements gradatively as we progress... > > > > > > Some issues that you have identified: > > > - Config model more flexible to accommodate differences between > > > multiple implementation > > > - Factory issues, and the ability to get different implementations > > > Are already available in my sandbox [1] as part of the work I did to > > > accommodate multiple DAS implementations [2] > > > > > > It's probably good idea to keep a XQuery DAS page on the Wiki and keep > > > updating it with requirements, discussions and design we are taking... > > > > > > [1] - > > > > https://svn.apache.org/repos/asf/incubator/tuscany/sandbox/lresende/das/ > > > [2] - > > > http://www.mail-archive.com/tuscany-dev@ws.apache.org/msg14428.html > > > > > > On 3/26/07, Amita Vadhavkar <[EMAIL PROTECTED]> wrote: > > > > > > > > Hi All, > > > > I am trying to create a prototype for supporting XQuery-DAS. Below > are > > > > some points I have gathered so far. > > > > Please give your comments, add to the points. > > > > > > > > 1) Basic Features that can be supported:- > > > > >>Need to support associating path expression to xml data source. > > > > > > > > >>Parameter passing in path expression > > > > > > > > >>Support for FLWOR expressions - use of parameters, data source > name > > > > > > > > >>JOIN operation will involve multiple data sources and multiple > > > > expressions > > > > - need to support association > > > > for same. > > > > > > > > >>Support for XQuery update facility > > > > > > > > 2) Places where current das config/code needs to be modified:- > > > > >>Provide flexibility in config to support RDB/XQUery/xyz...Can have > > > > expansion to > > > > current config.xsd to support multiple connections of multiple > types? > > > like > > > > RDB/XQuery... > > > > > > > > >>Command - needs to take care of associating multiple data sources > > > with > > > > multiple expressions > > > > say, in RDB - its select from t1, t2... > > > > in XQuery - the FLWOR - we can say books.xml <-> expr1, stores.xml <-> > > > > expr2 > > > > and have a JOIN. > > > > > > > > >>Getting connection to data store - should be in Interface-Impl , > not > > > > directly in impl- like > > > > it is currently there in DASImpl not in DAS, to keep it generic. > > > > > > > > >>graph building related classes should also have separation of > > > interface > > > > and implementation. > > > > > > > > > > > > 3) What can be kept for in-future and what is MUST for the first > cut:- > > > > Need comments from you all. > > > > > > > > 4) Questions:- > > > > >>In RDB-DAS we do not support connection to multiple databases. > Even > > > > JIRA-952 talks > > > > only about multiple schemas. Is there any requirement for this/ > > > constraint > > > > due to which > > > > we need to stick to single database? > > > > > > > > >>Also, in future, there can be mix of data stores, RDB, XQuery, > .... > > > What > > > > are the pros/cons > > > > for supporting connection to multiple different types of datastores > > > > (like one RDB compliant, one XQuery compliant) > > > > > > > > 5) Link from ML - [DAS] Refactoring DAS to allow multiple > > > implementatons > > > > http://www.mail-archive.com/tuscany-dev@ws.apache.org/msg14428.html > > > > During the attempt to separate APIs from Impl, we can now decide on > > > the > > > > approach and structure the design. > > > > > > > > Regards, > > > > Amita > > > > > > > > > > > > > > > > -- > > > Luciano Resende > > > http://people.apache.org/~lresende > > > > > > > >
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