I get the following error when I try to build ant
c:/ant build
error: javax.persistence.* does not exist

somebody suggested to put JPA in classpath in build.xml , but how to do that I do not know. Please explain in bit detail.

Thank you

You need the JPA spec as a minimum for compiling your code (you need to provide this on the compiler's classpath), but you also need some JPA implementation at runtime (this comes as a part of your EJB 3.0 complient app server).

One option is to find the needed JPA spec jar on your development-time app server, and add it to the classpath. Another option is to add the JPA spec jar to your application.

JPA website:
http://java.sun.com/javaee/technologies/persistence.jsp
EJB 3.0 spec (contains JPA spec):
http://java.sun.com/products/ejb/docs.html