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ADFm
February 28, 2012
Best practice invoking business services methods from JSF beans
Recently there was an increasing interest on OTN in best practices for invoking methods exposed on the ADF Business Components client interface. There exist two options to access methods exposed on ADF Business Components application modules and view objects from a managed bean through ADF.
- Call findDataControl(String) on the BindingContext and access the application module to invoke a method exposed on the Application Module or View Object client interface.
- Create a method binding on a PageDef level that binds to a method exposed on the Application Module or View Object client interface
Speaking of best practices, it’s the second option to use a method binding on the PageDef file that I recommend for the following reasons
- ADF is about abstracting the view and controller layer from the business service implementation details. A method binding instead exposes an ID (the name o the binding) to the JSF developer, which they use to access the binding from a managed bean using the OperationBinding API. Signature or name changes of a method exposed on the business service thus don't require a change in the managed bean(s) referencing it. All changes would be applied in metadata.
- ADF provides the OperationBinding class as an abstraction for business services methods. Configuring business service method access on the PageDef file using method bindings exposes a single and consistent API to application developers.
- Programmatic access to a method exposed on the business service require more lines of code than accessing the same method through the binding layer
- Direct business service access violates the recommendation to always work through the ADF binding layer and not to bypass it.
To access a method binding from a managed bean, use the following code
BindingContext bctx = BindingContext.getCurrent();
BindingContainer bindings = bctx.getCurrentBindingsEntry();
OperationBinding operationBinding =
bindings.getOperationBinding("name_of_method_binding");
//optional
operationBinding.getParamsMap().put("argumentName1",value1);
operationBinding.getParamsMap().put("argumentName2",value2);
//invoke method
operationBinding.execute();
if (!operationBinding.getErrors().isEmpty()) {
//check errors
List errors = operationBinding.getErrors();
...
}
//optional
Object methodReturnValue = operationBinding.getResult();
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Comments ( 2 )
i wonder how the second option is the best practice.
this technique has an issue if the method parameters change in any way (order, type, number), in this case only run time exception will be thrown and you will never be able to discover this at development time.
what do you think?
in my opinion, first option is the best to avoid such problem
operationBinding.getParamsMap().put("argumentName1",value1);
operationBinding.getParamsMap().put("argumentName2",value2);
then whenever the signature changes, you only need to change the two lines speaking to the map.