[Wsf-general] data services and resources

[Sanjiva Weerawarana]

Hi Sumedha,

> With some changes now data services supports following sql operations.
> 1. update
> 2. insert
> 3. delete
> 4. Select (with table joins)
> 5. create (creating tables, don't know how useful this will be. But with 
> few changes to code managed to get it working.)
> 
> Herewith I have attached the configuration files used for testing.

Excellent!

> Sample clients are available in svn 
> (https://wso2.org/repos/wso2/trunk/commons/data-services ) under the 
> package org.wso2.ws.dataservice.samples for all of the scenarios 
> mentioned above.
> But as of now, we do not have fully automated examples similar to ones 
> we find in axis2-samples or wsas. (I think this needs to be attended 
> before we write a tutorial for others.)

Can we support automatic ?wsdl generation from this? That's critical for 
success ... All you'd need to do is generate XML Schemas for the messages; 
the rest should be auto generated anyway from the AxisService we populate 
out of the dbs files. If you ask Deepal how he generates WSDL for POJOs 
that'll help figure out how to generate the schemas. Given our structure I 
think its quite easy.

> I would like to propose few changes to the specification.
> *1. We do not have a mechanism to specify parameter ordering. *
> 
> For example ordering is very important in the following query.
> 
>     <query id="addStudentInfo">
>        <!-- should appear in the correct order as in insert statement -->
>        <param name="id" sqlType="INTEGER"/>
>        <param name="name" sqlType="STRING"/>
>        <param name="deptNo" sqlType="INTEGER"/>
>        <param name="email" sqlType="STRING"/>
>        <sql>insert into student (id,name,deptNo,email) values 
> (?,?,?,?)</sql>
>      </query>
> 
> Right now in the code, it is assumed that user puts the 'param' elements 
> in the  correct ordering as how it should go into the insert statement.
> 
> We can have it like this or add an additional 'sequence/order' attribute 
> to 'param' element.

Hmmm. I think we need to implement the <with-param> stuff to complete the 
query invocation. At that time IMO its enough for v1.0 that we'll be 
putting out .. we can improve it later. Plus, that's critical for WSDL 
generation because that's what says how the binding will look.

> *2.  For queries returning large result sets,  we need to have some 
> mechanism to 'chunk' the result.*
> I am not 100% sure if this will workout, but I think we can use RM to 
> send chunks of the result set to client.

Yes .. but let's worry about this after getting a working model.

I doubt RM would work for this but HTTP chunking would. However, we 
probably want to allow users to select the start and end range or 
something like that too.

> *3. Response format for insert,update, delete*
> Out of CRUD operations only select statement generates an output (valuable).
> 
> As a work-a-round I have used following response format for other 
> operations.
> 
> <data:response xmlns:data="http://www.wso2.org/dataservices">
>     Your query executed successfully. Return code from the database was 1.
> </data:response>
> Along with the message, I have appended the return code (like the exit 
> code in C) from the database.
> 
> We need to come to an agreement on the suitability of this response format.

I don't think that's enough- what I'd like is to have some way to create 
an arbitrary XML element response. Essentially something like XSLT's 
xsl:element concept would work I think.

> *New Feature suggestion*
> (May be this is not the right time to suggest new features, with many 
> parts of the spec yet to be implemented ;-). But couldn't resist the 
> temptation. )
> 
> 1. Functionality to export returned data into various formats (eg. csv, 
> EDIFACT)
> In my last company we needed something like this to export some of our 
> data to third party integration tool (adaptris) & reporting tool 
> (clickview).

+1 ..

> The example section of the specification is bit outdated.  We need to 
> reorganize & update that part.

Yes- let's get the code working and then update the document with some 
real samples. We need to do finish <with-param> and ?wsdl before we can 
declare closure for an alpha level effort.

Sanjiva.
-- 
Sanjiva Weerawarana, Ph.D.
Founder, Chairman & CEO; WSO2, Inc.; http://www.wso2.com/
email: sanjiva at wso2.com; cell: +94 77 787 6880; fax: +1 509 691 2000

"Oxygenating the Web Service Platform."