Complex type support in process flow – XMLTYPE
By shawn wu on Mar 29, 2010
Before OWB 11.2 release, there are only 5 simple data types supported in process flow: DATE, BOOLEAN, INTEGER, FLOAT and STRING. A new complex data type – XMLTYPE is added in 11.2, in order to support complex data being passed between the process flow activities. In this article we will give a simple example to illustrate the usage of the new type and some related editors.
Suppose there is a bookstore that uses XML format orders as shown below (we use the simplest form for the illustration purpose), then we can create a process flow to handle the order, take the order as the input, then extract necessary information, and generate a confirmation email to the customer automatically.
Considering a simple user case here: we use an input parameter/variable with XMLTYPE to hold the XML content of the order; then we can use an Assign activity to retrieve the email info from the order; after that, we can create an email activity to send the email (Other activities might be added in practical case, but will not be described here).
1) Set XML content value
For testing purpose, we will create a variable to hold the sample order, and then this will be used among the process flow activities. When the variable is of XMLTYPE and the “Literal” value is set the true, the advance editor will be enabled.
Click the “Advance Editor” shown as above, a simple xml editor will popup. The editor has basic features like syntax highlight and check as shown below:
We can also do the basic validation or validation against schema with the editor by selecting the normalized schema. With this, it will be easier to provide the value for XMLTYPE variables.
2) Extract information from XML content
After setting the value, we need to extract the email information with the Assign activity. In process flow, an enhanced expression builder is used to help users construct the XPath for extracting values from XML content. When the variable’s literal value is set the false, the advance editor is enabled.
Click the button, the advance editor will popup, as shown below:
The editor is based on the expression builder (which is often used in mapping etc), an XPath lib panel is appended which provides some help information on how to write the XPath. The expression used here is: “XMLTYPE.EXTRACT(XML_ORDER,'/order/customer/email/text()').getStringVal()”, which uses ‘/order/customer/email/text()’ as the XPath to extract the email info from the XML document.
A variable called “EMAIL_ADDR” is created with String data type to hold the value extracted.
Then we bind the “VARIABLE” parameter of Assign activity to “EMAIL_ADDR” variable, which means the value of the “EMAIL_ADDR” activity will be set to the result of the “VALUE” parameter of Assign activity.
3) Use the extracted information in Email activity
We bind the “TO_ADDRESS” parameter of the email activity to the “EMAIL_ADDR” variable created in above step.
We can also extract other information from the xml order directly through the expression, for example, we can set the “MESSAGE_BODY” with value “'Dear '||XMLTYPE.EXTRACT(XML_ORDER,'/order/customer/name/text()').getStringVal()||chr(13)||chr(10)||' You have ordered '||XMLTYPE.EXTRACT(XML_ORDER,'/order/book/quantity/text()').getStringVal()||' '||XMLTYPE.EXTRACT(XML_ORDER,'/order/book/@id').getStringVal()”. This expression will extract the customer name, the quantity and the book id from the order to compose the message body.
To make the email activity work, we need provide some other necessary information, Such as “SMTP_SERVER” (which is the SMTP server used to send the emails, like “mail.bookstore.com”. The default PORT number is set to 25. You need to change the value accordingly), “FROM_ADDRESS” and “SUBJECT”. Then the process flow is ready to go.
After deploying the process flow package, we can simply run the process flow to check if the result is as expected (An email will be sent to the specified email address with proper subject and message body).
Note: In oracle 11g, there is an enhanced security feature - ACL (Access Control List), which restrict the network access within db, so we need to edit the list to allow UTL_SMTP work if you are using oracle 11g. Refer to chapter “Access Control Lists for UTL_TCP/HTTP/SMTP” and “Managing Fine-Grained Access to External Network Services” for more details.
In previous releases, XMLTYPE already exists in other OWB objects, like mapping/transformation etc. When the mapping/transformation is dragged into a process flow, the parameters with XMLTYPE are mapped to STRING. Now with the XMLTYPE support in process flow, the XMLTYPE will map to XMLTYPE in a more natural way, and we can leverage the new data type for the design.