Migrating Web based projects from Java to PHP

Question

At our work place after hours of coding, testing and QA we have successfully added a couple of software tools in our product line. We specialize in web based software solutions so in order to tap on more users we are now considering putting our developed solutions online for hosting and providing online access to all our clients for their products.

But what is coming in our way is that we have developed all these solutions in Java and compared to PHP Java hosting is very expensive. So we are now planing to migrate all these solutions to PHP while also maintaining their Java counterpart.

How we should start with these migration task?

We used AJAX in all our Java based solutions. Tech specs are

1. Front end web pages in JSP

2. Back end server side in Java using Apache Struts2

3. Database in MySQL

4. PDF report generation using iText PDF lib. for Java

NB: We have started a little with Code Igniter Framework in PHP.