Creating sample BPEL business processes

An Assign activity is usually used for manipulating data. For example, Assign activity can be used for copying the contents of one variable to another.

Assign activity is mainly used for copying the XML data contained in one BPEL variable to another BPEL variable. The data in a variable is visible and shared among all process activities.

Partner Link represents a link to services. JDeveloper's Source tab allows you to make the changes to the sources if required. The following screenshot shows how the Copy Rules tab can be used for creating a copy rule and connecting the source and target types:

In the sample BPEL process being shown in the preceding screenshot, input data from an input string is being copied to an output string using the concat function of XPath.

XPath is language for navigating through elements and attributes in an XML document and finding information within an XML document. The syntax of XPath's concat function is as follows:

fn:concat(string,string,...)

It returns the concatenation of the strings. For example, concat("My","first","XPATH function!") gives the output as My first XPATH function.

While copying the value of an input string to an output string, use the concat function of XPath to combine the strings together to manipulate the data. The Assign activities in BPEL build the XPath queries.

It is recommended to use the drag-and-drop feature for copying and assembling functions. The source code example of the Assign activity is given as follows (you can view the source code from JDeveloper' Source tab):

<assign>
   <copy>
      <from expression="concat('BPEL working ',
         bpws:getVariableData('input', 'payload', '/p:input))"/>
      <to variable="output" part="payload" query="/p:result/p:message"/>
   </copy>
</assign>

Assign activity in BPEL can do the following:

The Assign syntax of the copy function is as follows:

<copy> <from...> <to...> </copy>