Change code in an android program to call xml instead pf protobuffers

I am looking for someone to help change. the code in an application I have. Currently the application uses google protobuffers to receive data from the server. I wish to change the code of the program so instead of using the protobuffers it uses the xml / api to load data into the android app. (the app does a web request and an xml file is returned) The api is in the attached document please see the document for instructions