Re: [wsbpel] Issue - 63 - Support of Array

[Ricky Ho <riho@cisco.com>]

I'm not saying existing XSD mechanism cannot handle the repetitive 
processing need.  As illustrated in my previous response to David, it shows 
how the code will look like using existing XSD mechanism.  I hope I have 
highlighted the code complexity which can be greatly simplified if array is 
supported directly in BPEL.

Putting code complexity aside, I'm actually more uncomfortable of 
introducing a new complex type purely for the flow processing logic.  I 
consider complex type should mainly be used to represent the business 
document structure being exchanged, and these complex types should be 
defined inside the WSDL.  In your suggestion, I'm wondering where should I 
put the newly defined complex type ??

Take a look at the proven programming language.  Most programming language 
doesn't treat Array as a new type.  For example in Java, you need to define 
a "Person" class to represent a person, but "Person[]" is implicit, you 
don't need to define another class called "PersonArray".

Rgds, Ricky

At 10:50 PM 9/15/2003 -0400, Francisco Curbera wrote:




>Hi Ricky,
>
>WSDL 1.1 tried to add some form of array support; the WS-I basic profile
>now recommends that you use regular XSD mechanisms for doing this (that is,
>use the minOccurs/maxOccurs xsd attributes in your elements.) Seems like a
>reasonable solution to me. The alternative of introducing in BPEL  new type
>definition mechanisms and also a new ad hoc iterative contruct (I think
>that is what you are proposing) seems a bit heavy handed to me.
>
>Regards,
>
>Paco
>
>
>
>
> 
>
>                       Ricky 
> Ho 
>
>                       <riho@cisco.com>         To: 
> wsbpel@lists.oasis-open.org
>                                                cc: 
 >
>                       09/15/2003 03:47         Subject:  Re: [wsbpel] 
> Issue - 63 - Support of Array
>                       PM 
 >
> 
>
>
>
>
>
>Ron,
>
>There are two language here.  "the type defintion language", and the
>"execution flow language".  BPEL try to focus in the later while rely on
>XML Schema to cover the former, which I completely agree.  However, I don't
>see XML Schema is supporting "array" since you cannot have repetitive
>elements at the root level.
>
>Let me illustrate using a programming language which usually cover both the
>"type definition" and "execution flow" portions.  Lets say there is a
>user-defined type
>
>class Person {
>         String name;
>         String[] nickNames;
>         int age;
>}
>
>Approach 1:
>=========
>If the programming language supports Array, then you can declare your
>variable as ...
>Person[] myCustomers;
>
>
>Approach 2:
>=========
>However, if the programming language doesn't support Array, then you have
>to first define another "type"
>class PersonArray {
>         Person[] persons;
>}
>Then you declare your variable
>PersonArray myCustomers;
>
>
>Fortunately, most programming language supports Array so approach 1 is OK.
>However, until BPEL supports Array, then we have to go with approach 2
>which is more clumsy and tedious.
>
>Best regards,
>Ricky
>
>At 08:30 AM 9/15/2003 -0700, Ron Ten-Hove wrote:
>       Ricky,
>
>          Is this not just a type definition problem, for which we have XML
>       Schema?
>
>          This does touch on another issue -- the lack of the ability to
>       build an XML document up through multiple uses of <assign>, which
>       would be necessary in your example. This is already on the issues
>       list as issue 11.
>
>       -Ron
>
>At 07:35 PM 9/15/2003 +0100, ws-bpel issues list editor wrote:
>
>       This issue has been added to the wsbpel issue list. The issues list
>       is posted as a Technical Committee document to the OASIS WSBPEL TC
>       pages on a regular basis. The current edition, as a TC document, is
>       the most recent document with the title in the "Issues" folder of the
>       WSBPEL TC document list - the next posting will include this issue.
>       The list editor's working copy, which will normally include an issue
>       when it is announced, is available at this constant URL.
>       Issue - 63 - Support of Array
>
>
>       Status: open
>       Date added: 15 Sep 2003
>       Submitter: Ricky Ho
>       Date submitted: 15 September 2003
>       Description: Can BPEL declare a variable as a "collection" for a
>       particular message type ? For example, if there is a <while> which
>       will receive multiple incoming messages into an array variable. How
>       does the BPEL look like ?
>
>       I'm not proposing to define a new data type system for BPEL. We
>       should leverage what is already in XML schema. Although in the XML
>       schema there is a construct to declare repetitive occurrence of
>       element structure, it is designed for describing the XML document
>       being exchanged ? There is a difference between "there are some
>       repetitive elements within a document" and "there are multiple
>       documents".
>
>       Therefore, I propose that we need to support "Array"
>
>       For example, if a seller is receiving multiple POMessage from
>       multiple buyers, (assuming the complex type of POMessage is already
>       defined), the BPEL will look like this ..
>
>
>
>       <process>
>          <variables>
>            <array name="poArray"
>       type="POMessage"/>
>          </variables>
>
>
>
>          <sequence>
>            <iterate array="poArray"
>       count="10">
>              <receive
>       partner="buyer" ... array="poArray"/>
>            </iterate>
>       ....
>          </sequence>
>       </process>
>
>
>       Links: Ricky Ho, 13 Sep 2003     Ricky Ho, 13 Sep 2003     Mark
>       Little, 15 Sep 2003     Ron Ten-Hove, 15 Sep 2003
>       Changes: 15 Sep 2003 - new issue
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