Hi Experts,
I need your suggestions and idea regarding the scenario we have designed for our EJB-based
Banking system. I would appreciate if you give me advice and/or share your experience on
this.
In our Banking System, we've got a Central Bank Manager in which we have provided all
the bank services such as transferring money, returning balance, paying bills etc. and
other subsystems say, Internet Bank or Telephone Bank will be served through this Central
Bank Manager. The old Manager was developed in a very poor designation and now we are
going to develop it using EJB.
The scenario we are currently consider is to developing each banking services as an
session object. Actually, we have two kind of services, Loginless services that needs no
authentication and even authorization and Loginfull services which requires that the
customer first log in and then uses any available service that desires.
I assume the former services as Stateless session bean while the later ones as stateful
session beans.
My Idea is that we can provide a Login SFSB in which we have a login() business method
that have been tagged with @Init and a logout() method tagged with @Remove. Also, this
SFSB has a getService(ServiceType) method in which we can lookup the actual service that
the customer needs.
as an example:
|
| //A servlet from Internet Bank that serves login process
|
| public void doGet(...){
| //acquire username and password
| String username = ...
| String password = ...
|
| // lookup Login SFSB remote interface
| BankSession bankSession = ctx.lookup(...);
|
| Boolean ok = bankSession.login(username,password);
| if(ok){
| httpSession.setAttribute("bankSession", bankSession);
| }else{
| //redirect to an error page
| throw new Exception("invalid username or password");
| }
| }
|
now if user is authenticated then we store a bankSession in his/her session. but inside
the BankSession we have a getService() method which is actually a service locator that
looks up any desired service.
| @Statefull
| public class BankSession implements BankSessionRemote{
| // to assign a session id
| private String sessionId;
|
| @Init
| public boolean login(....){
| //code to logging in
| }
| public <T extends BankService> T getService(Class<T> klass){
| try{
| Context c = new InitialContext();
| Object sessionBean = c.lookup(klass.getName());
| ((BankService)sessionBean).setSessionId(sessionId);
| return (T) sessionBean;
| }catch(NamingException x){
| return null;
| }
| }
|
| @Remove
| public void logout(){
| sessionId = null;
| //rest of codes...
| }
| }
|
now, consider in another servlet which is responsible for transferring money we have:
| public class TransferServlet....{
| public void doGet(...){
| BankSession bankSession =
httpSession.getAttribute("bankSession");
| Transfer transfer = bankSession.getService(Transfer.class);
| transfer.execute(...);
| }
| }
|
if point is each time the logout() is called or the EJB timed out exception is occurred or
this session bean is disposed in any way the customer is no longer able to get any other
service that requires authentication. so in this way, we can make sure that everything is
working safely.
And one more thing is that because we set the session id through the getService() method,
neither of those services will work if they are acquired individually through the RMI
rather than our BankSession SFSB.
But the thing is that I don't know whether or not we can store the session bean as an
attribute in HttpSession or generally, if we store it in any structure and pass that
session bean to various classes and servlets, is it still keep its own relation with the
remote server?
And secondly, Does the locator we provide in getService() method work fine?
I am anxious to know your valuable idea on this and again I appreciate any suggestion on
this matter.
Thank you very much in advance
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