How to get DBconnection from a custom servlet

Question

Hi all:
In my JHeadstart Struts application, if we will using javascript to call a custom servlet program when some html event occur,
than how can we get db connection in our Servlet because we need get some database data through this Servlet,
we hope this Servlet can share dbconnection pool with JHeadstart that is consider for performance issue.
thanks a lot !

Answer 1

Ting Rung,
JHeadstart is based on the Model-View-Controller (MVC) principle. This means that the Model layer is responsible for communication with the database (and thus database connection pooling). Accessing the database directly from a JSP or Servlet is against the principles of MVC. JHeadstart uses BC4J as the technology to implement the model layer. By going through an BC4J Application Module to do some database action (for example calling a stored procedure as you mentioned in another thread) you automatically get the database connection pooling.
So, in the JHeadstart philosophy, we do not access the database from a servlet, instead we would do the following:
- write a method on the BC4J app module that performs the database action
- add a method to the apporpriate handler that calls this AM method
- write a custom Struts action that calls the handler method
Having said this, nobody will stop you from doing database access in a servlet. But JHeadstart might not be the right choice for you if you do not want to stick with the principles of MVC.
Here is a link that provides you with some more background information about MVC, may be it can help you deciding what the best approach for your application is:
http://java.sun.com/blueprints/guidelines/designing_enterprise_applications_2e/web-tier/web-tier5.html
You can also "google" on model-view-controller if you like.
Steven Davelaar,
JHeadstart Team.