Here are few workflow examples that invoke SOAP method calls.
You may find more examples in the "examples" directory of the source distribution of this plugin.
This workflow uses a sort WebService (refer to Linuxtoolbox Web Services) in order to sort the numbers "15 8 0" and "7 0 0".

Here is the original GWorkflowDL XML:
<?xml version="1.0" encoding="UTF-8"?>
<workflow xmlns="http://www.gridworkflow.org/gworkflowdl" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.gridworkflow.org/gworkflowdl http://www.gridworkflow.org/kwfgrid/src/xsd/gworkflowdl_2_1.xsd http://www.gridworkflow.org/gworkflowdl/operationclass http://www.gridworkflow.org/kwfgrid/src/xsd/gworkflowdl_operationclass_2_0.xsd"
ID="No_ID">
<!-- $Id: gworkflowdl_sort.xml 1359 2010-03-05 15:55:43Z andreas.hoheisel@first.fraunhofer.de $ -->
<description>little workflow example with condition, side effect, and places related to data classes</description>
<property name="occurrence.sequence" />
<property name="faultManagementPolicy">AbortOnActivityTerminated</property>
<place ID="begin">
<token ID="d1">
<data>
<value xmlns="" xsi:type="xsd:string">15
8
0</value>
</data>
</token>
<token ID="d2">
<data>
<value xmlns="" xsi:type="xsd:string">7
0
0</value>
</data>
</token>
</place>
<place ID="parameter">
<token ID="d3">
<data>
<param xmlns="" xsi:type="xsd:string">-n</param>
</data>
</token>
<token ID="d4">
<data>
<param xmlns="" xsi:type="xsd:string">-n</param>
</data>
</token>
</place>
<place ID="outputData" />
<place ID="hasBeenSorted" />
<transition ID="sort">
<description>sorts strings or numbers</description>
<property name="icon.url">http://fhrg.first.fraunhofer.de:8080/linuxtoolbox/images/text.png</property>
<inputPlace placeID="begin" edgeExpression="value" />
<inputPlace placeID="parameter" edgeExpression="params" />
<outputPlace placeID="outputData" edgeExpression="*" />
<outputPlace placeID="hasBeenSorted" />
<condition>string-length($value) > 0</condition>
<condition>$params/@xsi:type = "xsd:string"</condition>
<operation>
<oc:operationClass xmlns:oc="http://www.gridworkflow.org/gworkflowdl/operationclass" name="urn:dgrdl:service:sort">
<oc:operationCandidate type="soap" operationName="sort" resourceName="http://fhrg.first.fraunhofer.de:8080/linuxtoolbox/services/Sort?wsdl" selected="true" />
</oc:operationClass>
</operation>
</transition>
</workflow>This workflow invokes a "plus" service within a loop.

Here is the original GWorkflowDL XML:
<?xml version="1.0" encoding="UTF-8"?>
<workflow xmlns="http://www.gridworkflow.org/gworkflowdl"
xmlns:oc="http://www.gridworkflow.org/gworkflowdl/operationclass"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.gridworkflow.org/gworkflowdl http://www.gridworkflow.org/kwfgrid/src/xsd/gworkflowdl_2_1.xsd http://www.gridworkflow.org/gworkflowdl/operationclass http://www.gridworkflow.org/kwfgrid/src/xsd/gworkflowdl_operationclass_2_0.xsd"
ID="No_ID">
<description>small concrete workflow with loop</description>
<property name="occurrence.sequence" />
<place ID="begin">
<token>
<data>
<counter xmlns="" xsi:type="xsd:int">0</counter>
</data>
</token>
</place>
<place ID="addme">
<token>
<data>
<one xmlns="" xsi:type="xsd:int">1</one>
</data>
</token>
</place>
<place ID="result" />
<place ID="end" />
<transition ID="i_plus_plus">
<description>i++</description>
<property name="icon.url">http://fhrg.first.fraunhofer.de:8080/linuxtoolbox/images/plus.png</property>
<readPlace placeID="addme" edgeExpression="b" />
<inputPlace placeID="begin" edgeExpression="a" />
<outputPlace placeID="result" edgeExpression="$plusReturn" />
<operation>
<oc:operationClass>
<oc:operationCandidate type="soap" operationName="plus" resourceName="http://fhrg.first.fraunhofer.de:8080/linuxtoolbox/services/Calculator?wsdl" selected="true" />
</oc:operationClass>
</operation>
</transition>
<transition ID="continue">
<description>continue loop if plusReturn is less than 5</description>
<property name="icon.url">http://fhrg.first.fraunhofer.de:8080/linuxtoolbox/images/play.png</property>
<inputPlace placeID="result" edgeExpression="plusReturn" />
<outputPlace placeID="begin" edgeExpression="$plusReturn" />
<condition>$plusReturn < 5</condition>
</transition>
<transition ID="break">
<description>end loop if plusReturn is greater or equal 5</description>
<property name="icon.url">http://fhrg.first.fraunhofer.de:8080/linuxtoolbox/images/stop.png</property>
<property name="isQuasiLive">true</property>
<inputPlace placeID="result" edgeExpression="plusReturn" />
<outputPlace placeID="end" edgeExpression="$plusReturn" />
<condition>$plusReturn >= 5</condition>
</transition>
</workflow>