Key Concepts:
·
POJOs
are used for the java Callout
·
No
Special libraries or compilation is required
·
Java
method must be static(technically public and static ) in order to be call by
OSB
·
Java
code must be packaged in a JAR file
·
The
same Java Callout JAR can be called from multiple proxy services
Using Java Primitives:
There are few following steps
1.
Create
simple java project ex: Java callout project and inside project create package
ex: com.oracle.osb.project . Inside project create a class file
SimpleCallout.java.
2.
Inside
class file create two methods
Ø One takes a string argument and
return hello and whatever given string argument. its typically Hello worlds type of scenario .
Ø And next one takes two arguments and
multiply both the arguments and returns product the two arguments.
3.
Java
Code :
public static String getGreeting(String name)
{
return "hello" + name;
}
public static int multiply(int a,int b)
{
return a*b;
}
}
4.
Basically
Compile this. Right click on Java callout project -> Build Path->Add
external archives.
5.
In
order to access oracle Service Bus project change Recourse to oracle Service
Bus.
6.
Create
OSB configuration project and inside configuration project create OSB project.
7.
Now
create 3 folders
Ø WSDLs
Ø Proxy services
Ø JAR
8.
Inside
WSDLs folder create wsdl file that defines the element.
Ø Define two elements getGreeting and
Multiplication.
Ø getGreeting takes string argument and
returns string back
Ø Multiplication takes two different
integer argument and return single integer result argument.
Ø Wsdl file look like
9.
Now
copy the Java callout.jar to JAR folder.
10.
Create proxy service inside proxy services
folder.
Ø Select general view and select WSDL
Web Services.
Ø Browse WSDL particular WSDL file and
port.
Ø Now go to Message fellow Create
Operational branch one for Greeting and another for Multiplication
Ø Select getGreeting Branch and drag
and drop Pipeline pair.
Ø Create stage in Request pipeline and
inside stage create Java callout.
Ø And go to Java callout properties
tabs. Browse to the jar file. ex: javacallout.jar and specific operation in
case is greeting.
Ø Now pass the arguments. Click on
expression and pass getGreeting argument. Ex: $body/proxy:getGreeting/in/text()
Ø Result come back . and map that into
greeting. Result value is greeting.
Ø In Response pipeline Create stage.
And inside stage create Assign and replace operation .
Ø Select Assign operation. Click on Expression
and write particular expression, Ex: <proxy:getGreetingResponse>
<out>{$greeting}</out>
</
proxy:getGreetingResponse>
Ø And variable is responseDoc.
Ø Now select Replace operation.
i.
XPath:
.
ii.
In
Variable: body
iii.
Expression
: $responseDoc
iv.
And
check Replace node contents
11.
Do
same steps for multiplication branch
12.
Message
Fellow Look Like
13. Now debug on server.
When to use a java call out:
Ø New to the oracle service bus
programmer.
Ø Custom Validation
Ø Custom Transformation
Ø Custom Authentication
Ø Lookups for message enrichment
Ø Custom routing rules
Best Practices :
Ø Keep JavaCallout JAR file small and
simple
Ø The JAR is dynamically loaded when
they are first referenced
Ø Large Java frame work libraries
should be on the system class of the server
Ø Avoid creating threads in JavaCallout
code
Ø POJOs must be thread safe
