I generate new project. The only thing I create is assign activity.
First deploy done but process don't work. I look to example hello and throw off generated tags and write new example like.
Next problem I solve is add query to because generated WSDL schema use complexType ulike hello example where only part is used.
When I assign straight from one variable to another everything is fine but when I try to assign expression concat('text', getVariableData('input', 'payload', '/tns:input')) process stop working.

<types>
<schema targetNamespace="http://eclipse.org/bpel/text" xmlns="http://www.w3.org/2001/XMLSchema">
<element name="textRequest">
<compexType>
<sequence>
<element name="input" type="string"/>
</sequence>
</compexType>
</element>
...

<message name="textRequestMessage">
<part name="payload" element="tns:textRequest"/>
</message>

BPEL
<bpws:assign name="textAssign">
<bpws:copy keepSrcElementName="yes">
<bpws:from>
<expression>concat('text ', concat('text', getVariableData('input', 'payload', '/tns:payload/input'))</expression>
</bpws:from>
<bpws:to part="payload" variable="output" query="/tns:payload/result"/>
</bpws:copy>
</bpws:assign>