If you want to access an Cloud Endpoints API from a Python client, you need
to use the [Google APIs Python Client Library](https://github.com/google/google-api-python-client).
If the API doesn't require any authentication, your client can access the API as
shown in the following example code:

```python
import pprint

from googleapiclient.discovery import build


def main():
  # Build a service object for interacting with the API.
  api_root = 'https://guestbook.appspot.com/_ah/api'
  api = 'guestbook'
  version = 'v0.2'
  discovery_url = '%s/discovery/v1/apis/%s/%s/rest' % (api_root, api, version)
  service = build(api, version, discoveryServiceUrl=discovery_url)

  # Fetch all greetings and print them out.
  response = service.greetings().list().execute()
  pprint.pprint(response)

  # Fetch a single greeting and print it out.
  response = service.greetings().get(id='9001').execute()
  pprint.pprint(response)


if __name__ == '__main__':
  main()
```

In the example code:

- `api_root` is the frontend root URL under which your API methods are exposed. Usually, the URL is `https://YOUR_PROJECT_ID.appspot.com/_ah/api` where `YOUR_PROJECT_ID` represents your Google Cloud
- `api` is the name of the API.
- `version` is the version of the backend API.

### Accessing an API requiring Authentication

If the backend API requires authentication, you need use both the
[Google APIs Python Client Library](https://github.com/google/google-api-python-client)
and the [OAuth2.0 Client Library](https://github.com/google/oauth2client).

Your client can get the required authorization and access the API
by using code similar to the following:

```python
import argparse
import pprint
import sys

from googleapiclient import discovery
import httplib2
import oauth2client
from oauth2client import tools


CLIENT_ID = 'YOUR_CLIENT_ID'
CLIENT_SECRET = 'YOUR_CLIENT_SECRET'
SCOPE = 'https://www.googleapis.com/auth/userinfo.email'
USER_AGENT = 'my-cmdline-tool/1.0'
OAUTH_DISPLAY_NAME = 'My Commandline Tool'


def main(argv):
  # Parse command line flags used by the oauth2client library.
  parser = argparse.ArgumentParser(
      description='Auth sample',
      formatter_class=argparse.RawDescriptionHelpFormatter,
      parents=[tools.argparser])
  flags = parser.parse_args(argv[1:])

  # Acquire and store oauth token.
  storage = oauth2client.file.Storage('guestbook.dat')
  credentials = storage.get()

  if credentials is None or credentials.invalid:
    flow = oauth2client.client.OAuth2WebServerFlow(
        client_id=YOUR_CLIENT_ID,
        client_secret=YOUR_CLIENT_SECRET,
        scope=SCOPE,
        user_agent=USER_AGENT,
        oauth_displayname=OAUTH_DISPLAY_NAME)
    credentials = tools.run_flow(flow, storage, flags)
  http = httplib2.Http()
  http = credentials.authorize(http)

  # Build a service object for interacting with the API.
  api_root = 'https://guestbook.appspot.com/_ah/api'
  api = 'guestbook'
  version = 'v0.2'
  discovery_url = '%s/discovery/v1/apis/%s/%s/rest' % (api_root, api, version)
  service = discovery.build(
      api, version, discoveryServiceUrl=discovery_url, http=http)

  # Fetch all greetings and print them out.
  response = service.greetings().list().execute()
  pprint.pprint(response)

  # Fetch a single greeting and print it out.
  response = service.greetings().get(id='9001').execute()
  pprint.pprint(response)


if __name__ == '__main__':
  main(sys.argv)
```

Notice that `SCOPE` must be set as shown. For information about
`YOUR_CLIENT_ID` and
`YOUR_CLIENT_SECRET`, see
[Creating client IDs](https://docs.cloud.google.com/endpoints/docs/frameworks/python/creating-client-ids.md.txt).