Prerequisite
- Should have installed OSB
- Basics understanding of middleware technology.
Introduction
We can use XQuery/XSL in OSB to do the message transformation. But XQuery is preferred over the XSL because of the performance advantage. In this post I will show how to develop an xquery using the osb workshop eclipse.
XQuery - Introduction
XQuery is a light weight language which has got an xml like syntax. XQuery has 3 important parts as below
- Namespace declaration
- Set of function with their implementations
- Declaration of variables
- Mentioning the function with which the execution begins.
For further understanding of the XQuery you can refer
http://www.w3schools.com/xquery/xquery_intro.asp
Sample XQuery
Listing-1 xquery version "1.0" encoding "Cp1252";
Listing-2 (:: pragma parameter="$anyType1" type="xs:anyType" ::)
Listing-3 (:: pragma type="xs:anyType" ::)
Listing-4 declare namespace xf = "http://tempuri.org/OSB%20Project%203/sample/";
Listing-5 declare namespace ns1 = "http://tempuri.org/OSB%20Project%203/sample/inputaddress";
Listing-6 declare namespace ns2 = "http://tempuri.org/OSB%20Project%203/sample/outputaddress";
Listing-7
Listing-8 declare function xf:sample($requestDoc as element(*))
Listing-9 as element(*)
Listing-10 {
Listing-11 <ns2:Address>
Listing-12 <ns2:name>
Listing-13 {
Listing-14 $requestDoc/ns1:FirstName/text()
Listing-15 }
Listing-16 </ns2:name>
Listing-17 <ns2:phone>
Listing-18 {
Listing-19 $requestDoc/ns1:PhoneNumber/text()
Listing-20 }
Listing-21 </ns2:phone>
Listing-22 </ns2:Address>
Listing-23 };
Listing-24
Listing-25 declare variable $requestDoc as element(*) external;
Listing-26
Listing-27 xf:sample($requestDoc)
Explanation
Listing 1 - declaration of xquery
Listing 2 to 3 - comments
Listing 4 to 6 - Namespace declarations
Listing 8 to 9
This is the code snippet for the function 'sample' which takes 'requestDoc' which is of type element(*), that is the xml. It returns the type element(*) which is also an xml.
Listing 10 - shows the start of the xquery function
Listing 23 - shows the end of the xquery function
Listing 11 to 22 - the body of the function 'sample'
Here we are doing the transformation. What ever we write it in these lines will be the final output of the
xquery tranformation
Listing 14 or 19 - Here we are assigning the data obtained from request xml to the output response xml.
Listing 25 - declaring the request variable 'requestDoc' as 'external' as type 'element(*)'. So when we test this xquery from the OSB flow, we will bind the request xml with 'requestDoc' variable and we can transform the request xml to the response xml.
Listing 27 - This is the last line of the xquery where the execution of the xquery begins. Suppose if we have multiple functions, what ever function is given in the last line of xquery will be the entry point of execution.
Development of XQuery in OSB Workshop - Eclipse
Open the eclipse and create a project . Right click on the project and create a new xquery
Give some name
Now give the request binding variables.
Here I have added only one variable.
Give the 'Parameter Name' as 'requestDoc' and click on 'Add' so that we can add the request binding variable.
Similarly mention the response also
Now we have created the xquery. It will be now opened in the osb eclipse editor. The editor has 3 parts.
- Design
- Source
- Test
We can use 'Design' part if we have the source and destination schemas.
Now click on 'Source' and you can see the xquery source code.
Now modify the xquery as below
xquery version "1.0" encoding "Cp1252";
(:: pragma parameter="$anyType1" type="xs:anyType" ::)
(:: pragma type="xs:anyType" ::)
declare namespace xf = "http://tempuri.org/OSB%20Project%203/sample/";
declare namespace ns1 = "http://tempuri.org/OSB%20Project%203/sample/inputaddress";
declare namespace ns2 = "http://tempuri.org/OSB%20Project%203/sample/outputaddress";
declare function xf:sample($requestDoc as element(*))
as element(*)
{
<ns2:Address>
<ns2:name>
{
$requestDoc/ns1:FirstName/text()
}
</ns2:name>
<ns2:phone>
{
$requestDoc/ns1:PhoneNumber/text()
}
</ns2:phone>
</ns2:Address>
};
declare variable $requestDoc as element(*) external;
xf:sample($requestDoc)
Sample request xml for Testing
<ns1:AddressDetails xmlns:ns1="http://tempuri.org/OSB%20Project%203/sample/inputaddress">
<ns1:FirstName>Sajeev</ns1:FirstName>
<ns1:PhoneNumber>09962551082</ns1:PhoneNumber>
</ns1:AddressDetails>
Testing the application
Now Click on the 'Test' tab inside the xquery editor for testing
Now we have successfully created an xquery and tested it.
Testing the XQuery inside OSB Message Flow
Create a new sample osb project. If you are a beginner you can refer the below post
In the request flow drag one 'replace' node
Click on 'XPath' and enter the value as '*'
In Variable : body
Now click on 'Expresssion' and click on 'XQuery Resource' and browse to the sample xquery
and enter $body/* into the 'requestDoc'.
Now you can deploy the application and test it.
Conclusion
This topic is intended to give an introduction to Xquery development and using the same inside the osb message flow. You can better explore more.
Queries?
please contact Sajeev Ramakrishnan
@ sajurrk@gmail.com
@ saju_rrk@yahoo.com
JMS API architecture diagram
