convert readme to reStructured Text and add some more details

Author: Mike Dirolf

README

@@ -0,0 +1,79 @@
+
+=========================
+Mongo AppEngine Connector
+=========================
+:Info: See `the mongo site <http://www.mongodb.org>`_ for more  information.  See `github <http://github.com/mongodb/mongo-appengine-connector/tree>`_ for the latest source.
+:Author: Mike Dirolf <mike@10gen.com>
+
+About
+=====
+The Mongo AppEngine Connectory provides a drop-in replacement for App Engine's
+datastore API, using MongoDB as a backend.
+
+Usage
+=====
+This adaptor has been tested against revision 41 from Google
+AppEngine's svn repository. The following patch (generated by `svn
+diff`) shows how to modify the AppEngine code in order to use MongoDB::
+
+> Index: dev_appserver.py
+> ===================================================================
+> --- dev_appserver.py    (revision 41)
+> +++ dev_appserver.py    (working copy)
+> @@ -37,6 +37,7 @@
+>  SCRIPT_DIR = os.path.join(DIR_PATH, 'google', 'appengine', 'tools')
+>
+>  EXTRA_PATHS = [
+> +  "PATH/TO/MONGO-APPENGINE-CONNECTOR/DIRECTORY",
+>    DIR_PATH,
+>    os.path.join(DIR_PATH, 'lib', 'antlr3'),
+>    os.path.join(DIR_PATH, 'lib', 'django'),
+> Index: google/appengine/tools/dev_appserver.py
+> ===================================================================
+> --- google/appengine/tools/dev_appserver.py (revision 41)
+> +++ google/appengine/tools/dev_appserver.py (working copy)
+> @@ -75,7 +75,7 @@
+>  from google.appengine.api import apiproxy_stub_map
+>  from google.appengine.api import appinfo
+>  from google.appengine.api import datastore_admin
+> -from google.appengine.api import datastore_file_stub
+> +import datastore_mongo_stub
+>  from google.appengine.api import mail_stub
+>  from google.appengine.api import urlfetch_stub
+>  from google.appengine.api import user_service_stub
+> @@ -3001,7 +3001,7 @@
+>
+>    apiproxy_stub_map.apiproxy = apiproxy_stub_map.APIProxyStubMap()
+>
+> -  datastore = datastore_file_stub.DatastoreFileStub(
+> +  datastore = datastore_mongo_stub.DatastoreMongoStub(
+>        app_id, datastore_path, history_path, require_indexes=require_indexes)
+>    apiproxy_stub_map.apiproxy.RegisterStub('datastore_v3', datastore)
+
+The path added to *dev_appserver.py* should be replaced with the path
+where this directory is located on your machine. This patch should then be
+applied against a clean version of the AppEngine svn repository.
+
+Other Notes
+===========
+You must have a copy of the `PyMongo distribution <http://pypi.python.org/pypi/pymongo/>`_
+installed in order to use the AppEngine Connector.
+
+Right now, the Connection cannot be configured. It attempts to
+connect to a standalone MongoDB instance on localhost:27017.
+
+Transactions are unsupported. When any operation requiring
+transactions is performed a warning will be logged and the operation
+will be performed transaction-less.
+
+DateTime values get rounded to the nearest millisecond when saved to
+MongoDB. This is a limitation of MongoDB's date representation, and is
+not specific to this adaptor.
+
+In order to actually create indexes the dev_appserver must be run with
+the --require-indexes option. Running with this option will probably
+add significant overhead, since each time the dev_appserver checks to
+see if it should create an index a query is performed.
+
+Index creation ignores the "Ancestor" option. This option would just create an
+index on '_id', which (soon) MongoDB creates automatically anyway.