Posted by Wesley Chun (@wescpy), Developer Advocate, G Suite
While most chatbots respond to user requests in a synchronous way, there are scenarios when bots don't perform actions based on an explicit user request, such as for alerts or notifications. In today's DevByte video, I'm going to show you how to send messages asynchronously to rooms or direct messages (DMs) in Hangouts Chat, the team collaboration and communication tool in G Suite.
What comes to mind when you think of a bot in a chat room? Perhaps a user wants the last quarter's European sales numbers, or maybe, they want to look up local weather or the next movie showtime. Assuming there's a bot for whatever the request is, a user will either send a direct message (DM) to that bot or @mention the bot from within a chat room. The bot then fields the request (sent to it by the Hangouts Chat service), performs any necessary magic, and responds back to the user in that "space," the generic nomenclature for a room or DM.
Our previous DevByte video for the Hangouts Chat bot framework shows developers what bots and the framework are all about as well as how to build one of these types of bots, in both Python and JavaScript. However, recognize that these bots are responding synchronously to a user request. This doesn't suffice when users want to be notified when a long-running background job has completed, when a late bus or train will be arriving soon, or when one of their servers has just gone down. Recognize that such alerts can come from a bot but also perhaps a monitoring application. In the latest episode of the G Suite Dev Show, learn how to integrate this functionality in either type of application.
From the video, you can see that alerts and notifications are "out-of-band" messages, meaning they can come in at any time. The Hangouts Chat bot framework provides several ways to send asynchronous messages to a room or DM, generically referred to as a "space." The first is the HTTP-based REST API. The other way is using what are known as "incoming webhooks."
The REST API is used by bots to send messages into a space. Since a bot will never be a human user, a Google service account is required. Once you create a service account for your Hangouts Chat bot in the developers console, you can download its credentials needed to communicate with the API. Below is a short Python sample snippet that uses the API to send a message asynchronously to a space.
from apiclient import discovery
from httplib2 import Http
from oauth2client.service_account import ServiceAccountCredentials
SCOPES = 'https://www.googleapis.com/auth/chat.bot'
creds = ServiceAccountCredentials.from_json_keyfile_name(
'svc_acct.json', SCOPES)
CHAT = discovery.build('chat', 'v1', http=creds.authorize(Http()))
room = 'spaces/<ROOM-or-DM>'
message = {'text': 'Hello world!'}
CHAT.spaces().messages().create(parent=room, body=message).execute()
The alternative to using the API with service accounts is the concept of incoming webhooks. Webhooks are a quick and easy way to send messages into any room or DM without configuring a full bot, i.e., monitoring apps. Webhooks also allow you to integrate your custom workflows, such as when a new customer is added to the corporate CRM (customer relationship management system), as well as others mentioned above. Below is a Python snippet that uses an incoming webhook to communicate into a space asynchronously.
import requests
import json
URL = 'https://chat.googleapis.com/...&thread_key=T12345'
message = {'text': 'Hello world!'}
requests.post(URL, data=json.dumps(message))
Since incoming webhooks are merely endpoints you HTTP POST to, you can even use
curl to send a message to a Hangouts Chat space from the
command-line:
curl \
-X POST \
-H 'Content-Type: application/json' \
'https://chat.googleapis.com/...&thread_key=T12345' \
-d '{"text": "Hello!"}'
To get started, take a look at the Hangouts Chat developer documentation, especially the specific pages linked to above. We hope this video helps you take your bot development skills to the next level by showing you how to send messages to the Hangouts Chat service asynchronously.
