[chromedriver] Allow commands to be async.

chrome/test/chromedriver/README.txt

Index: chrome/test/chromedriver/README.txt
diff --git a/chrome/test/chromedriver/README.txt b/chrome/test/chromedriver/README.txt
index 35f0d5466f2fa0020a6ecaefd4bb1a36bb6e0f80..03154fecae8a75b8850a407f0586984ac924d40e 100644
--- a/chrome/test/chromedriver/README.txt
+++ b/chrome/test/chromedriver/README.txt
@@ -4,10 +4,12 @@ contribute.
 ChromeDriver is an implementation of the WebDriver standard,
 which allows users to automate testing of their website across browsers.
 
+See the user site at http://code.google.com/p/chromedriver.
+
 =====Getting started=====
 Build ChromeDriver by building the 'chromedriver2_server' target. This will
-create an executable binary in the build folder named 'chromedriver2_server.exe'
-on Windows or 'chromedriver2_server' on Mac and Linux.
+create an executable binary in the build folder named
+'chromedriver2_server[.exe]'.
 
 Once built, ChromeDriver can be used interactively with python.
 
@@ -31,26 +33,30 @@ more detailed instructions see the wiki:
 
 =====Architecture=====
 ChromeDriver is shipped separately from Chrome. It controls Chrome out of
-process through DevTools (WebKit Inspector). ChromeDriver is a standalone server
-executable which communicates via the WebDriver JSON wire protocol. This can be
-used with the open source WebDriver client libraries.
-
-When a new session is created, a new thread is started that is dedicated to the
-session. All commands for the session runs on this thread. This thread is
-stopped when the session is deleted. Besides, there is an IO thread and it is
-used to keep reading incoming data from Chrome in the background.
+process through DevTools. ChromeDriver is a standalone server which
+communicates with the WebDriver client via the WebDriver wire protocol, which
+is essentially synchronous JSON commands over HTTP. WebDriver clients are
+available in many languages, and many are available from the open source
+selenium/webdriver project: http://code.google.com/p/selenium.
+
+ChromeDriver has several threads. The webserver code, third_party/mongoose,
+spawns a thread for the server socket and a certain amount of request handling
+threads. When a request is received, the command is processed on the message
+loop of the main thread, also called the command thread. Commands may be handled
+asynchronously on the command thread, but the request handler threads
+will block waiting for the response. One of the commands allows the user to
+create a session, which includes spawning a dedicated session thread. Session
+commands will be dispatched to the session thread and handled synchronously
+there. Lastly, there is an IO/net thread on which the net/ code operates.
+This is used to keep reading incoming data from Chrome in the background.
 
 =====Code structure=====
-Code under the 'chrome' subdirectory is intended to be unaware of WebDriver and
-serve as a basic C++ interface for controlling Chrome remotely via DevTools.
-As such, it should not have any WebDriver-related dependencies.
-
 1) chrome/test/chromedriver
 Implements chromedriver commands.
 
 2) chrome/test/chromedriver/chrome
-Code to deal with chrome specific stuff, like starting Chrome on different OS
-platforms, controlling Chrome via DevTools, handling events from DevTools, etc.
+A basic interface for controlling Chrome via DevTools. Should not have
+knowledge about WebDriver, and thus not depend on chrome/test/chromedriver.
 
 3) chrome/test/chromedriver/js
 Javascript helper scripts.
@@ -71,6 +77,9 @@ An extension used for automating the desktop browser.
 8) chrome/test/chromedriver/third_party
 Third party libraries used by chromedriver.
 
+9) third_party/mongoose
+The webserver for chromedriver.
+
 =====Testing=====
 There are 4 test suites for verifying ChromeDriver's correctness: