In the following example, the ssn field is copied from the CreditFlow process's input message into the ssn field of the credit rating service's input message.

<assign>
   <copy>
      <from variable="input" part="payload"
         query="/tns:CreditFlowRequest/tns:ssn"/>
      <to variable="crInput" part="payload" query="/tns:ssn"/>
   </copy>
</assign>

The following example shows how the BPEL file defines message type-based variables involved in this assignment:

<variable name="input" messageType="tns:CreditFlowRequestMessage"/>
<variable name="crInput"
          messageType="services:CreditRatingServiceRequestMessage"/>

The crInput variable is used as an input message to a credit rating service. Its message type, CreditFlowRequestMessage, is defined in the CreditFlowService.wsdl file, as shown in the following example:

<message name="CreditFlowRequestMessage">
<part name="payload" element="tns:CreditFlowRequest"/>
</message>

CreditFlowRequest is defined with a field named ssn. The message type CreditRatingServiceRequestMessage is defined in the CreditRatingService.wsdl file, as shown in the following example:

<message name="CreditRatingServiceRequestMessage">
   <part name="payload" element="tns:ssn"/>
</message>

The following example shows the BPEL 2.0 syntax for how the BPEL file defines message type-based variables involved in the assignment in the first assignment example. Note that /tns:CreditFlowRequest is not required.

<copy>
   <from>$input.payload/tns:ssn</from>
   <to>$crInput.payload</to>
</copy>

A BPEL process can also use element-based variables. The following example shows how to use element-based variables in BPEL 1.1. The autoloan field is copied from the loan application process's input message into the customer field of a web service's input message.

 <assign>  
      <copy>
        <from variable="input" part="payload" 
           query="/tns:invalidLoanApplication/autoloan:
            application/autoloan:customer"/>
        <to variable="customer"/>
      </copy>
</assign>

The following example shows how to use element-based variables in BPEL 2.0.

<assign>
   <copy>
      <from>$input.payload/autoloan:application/autoloan:customer</from>
      <to>$customer</to>
   </copy>
</assign>

The following example shows how the BPEL file defines element-based variables involved in an assignment:

    <variable name="customer" element="tns:customerProfile"/>