REST, SOAP or XML-RPC?

I am developing a webservice like module for our framework that will enable downloads of module code into the framework modules from a remote server. Basically what this should do is: 1. User requests a list of available stable modules from server 2. User clicks on install from the returned list 3. Client code will download a tgz/zip module and plonk it in the users modules directory (taken care of) 4. Framework then unzips/untars it and installs (taken care of) My question here is... For the server/client code, I am thinking around REST (much the same way as the PEAR channel server works). Is this the wisest choice? Should I rather go with FTP or a mail request or something? If I go for FTP, that will require the PHP FTP extension, how common is that in shared hosting environments? The file size of a typical module is around 100k, and we must take into account that this is in/for bandwidth starved Africa. Is REST/SOAP robust enough to do that? Any help would be greatly appreciated! --Paul