JAVA to SAP Integration - Delivering data to SAP from JSF web application

For this, you need a Java library called "SAP JCo" (=Java Connector), the current version number is 3 and you can download it from the SAP Service Marketplace (you need a customer ID though). There are two directions you can connect SAP and Java:

1.) You can call ABAP FMs from Java Programm.
* Go to SAP transaction se37 and make sure your FM (in my example "Z_YOUR_FM" is marked as "remote".
* Use some Java-Code like this:
Properties properties = new Properties();
properties.setProperty(DestinationDataProvider.JCO_ASHOST, "your.sap.xyt");
properties.setProperty(DestinationDataProvider.JCO_SYSNR,  "00");
properties.setProperty(DestinationDataProvider.JCO_CLIENT, "123"); // use own SAP client number
properties.setProperty(DestinationDataProvider.JCO_USER,   "user");
properties.setProperty(DestinationDataProvider.JCO_PASSWD, "password");
properties.setProperty(DestinationDataProvider.JCO_LANG,   "en");
File file = new File("sapconnection.jcoDestination");
FileOutputStream stream = new FileOutputStream(file, false);
properties.store(stream, "SAP connection properties");
stream.close();

JCoDestination destination = JCoDestinationManager.getDestination("sapconnection");
System.out.println(destination.getAttributes());

JCoRepository repository = destination.getRepository();
JCoFunction processTisTask = repository.getFunction("Z_YOUR_FM");
JCoParameterList importParameter = processTisTask.getImportParameterList();
JCoStructure data = importParameter.getStructure("DATA");
data.setValue("FIELD1", 1);
data.setValue("FIELD2", "two");
importParameter.setValue("DATA", data);
processTisTask.execute(destination);

2.) You can run a Java Programm as a Server that can be accessed from SAP.
* First create a connection (aka "destination") via SAP transaction "sm59"
* Create an ABAP FM in se37 and mark it as remotely callable.
* Use Java code similar to this:
JCoServer server = JCoServerFactory.getServer(SERVER_NAME);
JCoServerFunctionHandler handler = new YourHandler();
DefaultServerHandlerFactory.FunctionHandlerFactory factory =
  new DefaultServerHandlerFactory.FunctionHandlerFactory();
factory.registerHandler("Z_YOUR_FM", handler);
server.setCallHandlerFactory(factory);
server.start();

public class YourHandler implements JCoServerFunctionHandler {
  @Override
  public void handleRequest(JCoServerContext serverCtx, JCoFunction function)
      throws AbapException {
    String test = function.getImportParameterList().getString("TEST");
    // ...
  }
}
* Run your Java server program.
* In SAP check via sm59 that your program is found.
* When you now call your FM from ABAP code like this:
 CALL FUNCTION 'Z_YOUR_FM' DESTINATION dest EXPORTING ...
where "dest" is the destination that you created in sm59. Your Java-Handler gets called.

Thank you so much SprudeVI, That was very helpful.

As you have showed how to create a connection to SAP and insert a record into Z_YOUR_FM ( I assume it is a table right ?). (execuse me if I am wrong as my SAP skills limited at this time)

Whre did you use

could you please also try to show how would you read data from SAP tables?

Is it possible to deliver IDOCs from java program where my SAP team processes those IDocs at a later point in time or daily batch processesor (as long as my java program delivers IDocs to them ?

If it is too many questions in one question, please let me know I would not mind opening separate questions.

thank you.