FrontendImplementationDetails

Autotest Web Frontend Implementation details

Here we outline the building blocks and implementation details of the autotest web interface.

Overview

Here's a broad overview of how the system fits together:

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• The Django RPC server is an RPC server, written using the Django framework. It functions as a web server, accepting RPCs as HTTP POST requests, querying the MySQL database as necessary, and returning results. In a production environment, it runs within Apache using mod_python
  • The AFE server code lives under frontend/afe and uses the autotest_web database.
  • The TKO server code lives under new_tko/tko and uses the tko database.
  • In both servers, the RPC entry points are defined in rpc_interface.py.
  • All RPC POST requests go to a single URL, (afe|new_tko)/server/rpc/. They get dispatched to RPC methods by the code in rpc_handler.py. See Django documentation for an explanation of how HTTP requests get mapped to Python code using URLconfs.
  • Database models live in models.py. See Django documentation for an explanation of models.
• RPC calls and responses are encoded according to the JSON-RPC protocol.
  • JSON is a simple data representation format based on Javascript. See http://json.org.
  • JSON-RPC is a very simple standard for representing RPC calls and responses in JSON. See http://jsonrpc.org.
  • RPCs are made by sending a POST request to the server with the POST data containing the JSON-encoded request. The response text is a JSON-encoded response.
    • On the server, the code for serializing JSON lives at frontend/afe/simplejson. The code for forming and dispatching JSON-RPC requests lives at frontend/afe/json_rpc.
    • The CLI uses the same code for serializing JSON-RPC.
    • The GWT client uses GWT's builtin JSON library for serializing JSON. The code for handling JSON-RPC requests is in autotest.common.JsonRpcProxy and friends.
• The GWT client is a browser-based client for AFE and TKO (technically, there are two separate clients). It's written using Google Web Toolkit (GWT), a framework for writing browser apps in Java and having them compiled to Javascript. See http://code.google.com/webtoolkit.
  • More details...
• The CLI is a command-line Python application that makes calls to the RPC server. It lives under the cli directory. cli/atest is the main entry point.