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Developers and Practitioners

Developing bots for Hangouts Chat

June 13, 2018
Wesley Chun

Developer Advocate

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Do you feel like you live in a chat window, and wish it could do more? Google made Hangouts Chat generally available earlier this year to help. This messaging platform helps users easily collaborate from one place, and features archive and search, tighter G Suite integrations and the ability to create separate, threaded chat rooms. More importantly for developers, Chat includes a bot framework and API. Whether you want to automate common tasks, query information or perform other heavy-lifting, bots can help transform the way you work.

Speed up workflows with bots in Hangouts Chat 

In addition to plain text replies, Hangouts Chat can also display bot responses with richer user interfaces (UIs) called cards which can render header information, structured data, images, links, buttons and more. Users can also interact with these components, like updating displayed information. In the latest episode of the G Suite Dev Show, we talk about how to create a bot that features an updating interactive card.

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Pointers on building a Hangouts Chat bot The most important thing when bots receive a message is to determine the event type and take the appropriate action. Here are the types and how each work:

  • REMOVED_FROM_SPACE - A bot will perform any desired "paperwork" when it is added to or removed from a room or direct message (DM), generically referred to as a "space.” When added to a space, a bot will generally send a welcome message like, "Thank you for adding me to this room." No notifications are sent when a bot is removed from a space (because the bot has been removed… duh!). Developers typically just log that the bot has been removed. 
  • MESSAGE - Receiving an ordinary message sent by users is the most likely scenario. Most bots do "their thing" here in serving the request. 
  • CARD_CLICKED - The last event type occurs when a user clicks on an interactive card. Similar to receiving a standard message, a bot performs its requisite work, including possibly updating the card itself.
Below is some pseudocode summarizing these four event types and represents what a bot would likely do depending on the event type:


The bot pseudocode as well as the bot featured in the video respond synchronously. Bots performing more time-consuming operations, or those issuing out-of-band notifications, can send messages to spaces in an asynchronous way. This includes messages like notifications when a job is completed, alerts if a server goes down or pings to the Sales team when a new lead is added to the CRM (Customer Relationship Management) system.

Build your bot, your way 

While we demonstrate the bot implemented in JavaScript and Python in the video, one key takeaway is the flexibility of the platform: developers can use any language, any stack or any cloud to create and host their bot implementations. Bots only need to be able to accept HTTP POST requests coming from the Hangouts Chat service to function.

We recently delivered an overview of the bot framework at Google I/O 2018. This comprehensive tour of the framework includes live demos of sample bots in a variety of languages and platforms. Check it out:

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To get started, check out this post on the Google Developers blog or this post for a deeper dive into the Python App Engine version of the vote bot featured in the video.

You can learn more about developing bots for Hangouts Chat by reviewing the concept guides as well as this “how-to” on creating bots.

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