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bpel:doXslTransform(style-sheet-uri node-set)

Returns the result of an XSL transformation of a single element node set using the specified style sheet.

Parameters:

style-sheet-uri

: URI for the XSL file.

node-set

: XPath node set providing the source document for the transformation.

Example syntax:

bpel:doXslTransform("project:/myStylesheets/A2B.xsl", $A)

Optional parameters (must appear in pairs if specified)

string

: XPath string parameter providing the qualified name of an XSLT parameter.

object

: XPath object parameter providing the value for the named XSLT parameter.

Examples

The following examples show complex document transformation and iterative document construction.

Example 1. Complex Document Transformation.

A common pattern in a WS-BPEL process involves receiving an XML document from one service, converting it to a different schema to form a new request message, and sending the new request to another service. Such document conversion can be accomplished using XSLT via the

bpel:doXslTransform

function, as shown in the following example.

<variables>
    <variable name="A" element="foo:AElement" />
    <variable name="B" element="bar:BElement" />
</variables>
...
<sequence>
    <invoke ... inputVariable="..." outputVariable="A" />
    <assign>
      <from>
           bpel:doXslTransform("urn:stylesheets:A2B.xsl", $A)
      </from>
      <to variable="B" />
    </assign>
    <invoke ... inputVariable="B" ... />
</sequence>

In the sequence, a service is invoked, and the result (

foo:AElement)

copied to variable A. The assign activity transforms the contents of variable A to

bar:BElement

, and copies the result to variable B. Variable B is used to invoke another service. The style sheet,

A2B.xsl

, contains the XSL rules for converting documents of schema

foo:AElement

to schema bar:BElement
.

Example 2. Iterative Document Construction.

Suppose that a document is constructed by repeatedly calling a service and accumulating the result in a variable, as shown in the following example:

<variables>
   <variable name="PO" element="foo:POElement" />
   <variable name="OutVar" element="foo:ItemElement" />
</variables>
<!-- ... PO is initialized ... -->
<!-- Iteratively add more items to PO until complete -->
<while>
   <condition>...</condition>
    <sequence>
       <!-- Fetch next chunk into OutVar -->
     <invoke ... inputVariable="..." outputVariable="OutVar"/>
      <assign>
         <copy>
          <from>
            <expression>
               bpel:doXslTransform
                 ( "urn:stylesheets:AddToPO.xsl",
                   $PO, "NewItem", $OutVar)
            </expression>
          </from>
          <to variable="PO" />
         </copy>
     </assign>
    </sequence>
</while>

The optional parameters given in the

doXslTransform

call specify that the XSLT parameter named

NewItem

is set with the value of the process variable

OutVar

. To allow the XSLT style sheet access to this value, it contains a global (top-level) parameter with a name matching that given in the third parameter of the function call shown above.

<xsl:transform version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform" ...>
     <!-- NewItem variable set by WS-BPEL process; 
        defaults to empty item -->
    <xsl:param name="NewItem">
        <foo:itemElement />
    </xsl:param>
        ...
</xsl:transform>

The style sheet contains a template that appends the value of global parameter NewItem (the value of

OutVar

from the process instance) to the existing list of items in the PO variable.

<!-- line 1 -->  <xsl:template match="foo:itemElement">
<!-- line 2 -->  <xsl:copy-of select="." />
<!-- line 3 -->    <xsl:if test="position()=last()">
<!-- line 4 -->      <xsl:copy-of select="$NewItem" />
<!-- line 5 -->    </xsl:if>
<!-- line 6 -->  </xsl:template>

This template copies all existing items in the source document (lines 1 & 2) and appends the contents of the XSLT parameter

NewItem

to the list of items (lines 3 & 4). It tests to see if the current node is at the end of the item list (line 3) and copies the

result-tree

fragment from the XSLT parameter

NewItem

to follow the last item (line 4).

If PO has a value of:

<foo:poElement>
     <foo:itemElement>item 1</foo:itemElement>
</foo:poElement>

at the beginning of an iteration of the while loop and the invoke activity returns a value of

<foo:itemElement>item 2</foo:itemElement>

, evaluation of the from expression will result in a value of:

<foo:poElement>
     <foo:itemElement>item 1</foo:itemElement>
     <foo:itemElement>item 2</foo:itemElement>
</foo:poElement>

When the copy operation completes, it becomes the new value of the PO variable.

Adding an XSL Style Sheet to Process Server

A style sheet that you reference in a

doXslTransform

function is automatically recognized by Process Developer and is added to a BPR archive for deployment.

BPEL Functions

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bpel:doXslTransform(style-sheet-uri node-set)

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