Build a Website

I need to have a prototype version of client-server based workflow design and work environment. The client, which is responsible for editing workflow by using browser (cross browser compatibility is also important) and interacting with server (submitting workflow to server or querying information such as the progress of the outgoing processes in server etc.). The client uses Draw2D ([login to view URL]) or any other workflow design library to create/edit the workflow and stores it in a special XML format such as IBM BPEL, MoML etc. The Dropbox or Google Drive could be also used to store designed workflow in a user bases. The basic design of the interface could follow the design of Kepler scientific workflow application ([login to view URL]) and actors (smallest part of the workflow which are connected via connections or lines) must be automatically inherited from Kepler application (written in Java). The web based work environment (client) will also interact with a database (MySQL, Postgres etc.) to store different versions (by using a versioning tool such as SVN, GIT etc.) of the created workflows and must also have a strong authentication system that uses OpenID. The server, which is responsible for running workflows (designed by the client) in a Linux based environment. The server will also interact with Kepler ([login to view URL]) scientific workflow environemnt to run the workflow. The information about the intermediate stages (run, finish, waiting or progress - %) of the workflow must be send to the client in a user defined interval. The server should be able to stop, run or pause the workflow by interacting with the client. Both client and server must follow some basic coding conventions and standards. The code must be clear, well documented, hierarchically structured and easily extendable. The whole project will be open source and run in a Linux based servers (probably RedHat or Centos based). To create the web services (interaction between client and server) Django can be used but i am also open to any other suggestions for technologies and third-party libraries. The final decision will be given after short discussion of the other available options that will be suggested by the developer.