Batch Outgoing Message middleware

Introduction

batch-outgoing-message-middleware implements BotFramework class Middleware.

It is executed after the aura-bot recognizers, whenever a new turn is started. Then, it waits for the execution of all the middlewares and the rest of the components of aura-bot, and thus it is the last element to be executed.

The goal of this middleware is to handle all the activities within one response jointly, to avoid issues with activity.inputHint. setting also activity.channelData.hasMoreMessages field properly, if the channel request needs it (for example, if channelData version is lower than 2).

The source code of this middleware is included in Aura Bot Platform middlewares - Github repository.

The flow of the middleware is explained as follows:

1. First of all, batch-outgoing-message-middleware looks for any error stored in the TurnContext.

   • If there is no error, it would check if the bot is configured to use always batch processing of the activities being returned or if the channel needs it.

   • If some error exists in the TurnContext, nothing is done.

2. If there is no error and the bot or channel implies batch activities processing, it would get all the activities to be sent from TurnContext activities queue and handle them to:

   • Set inputHint properly in each activity. There are 3 different values, defined by BotFramework:

     • IgnoringInput: it should be sent when the answer of the bot counts on several activities in all of them but the last one, so it indicates the channel to ignore the messages of the user until the last activity arrives.

     • AcceptingInput: it should be sent in the last activity of the answer of the bot, except if there’s a prompt. It indicates the channel that could start handling user messages again.

     • ExpectingInput: it should be sent if the last activity of the answer of the bot if there’s a prompt in it, it indicates the channel that the bot has asked something to the user and it is waiting for her response.

   • It also includes in the channelData of each activity the proper value for hasMoreMessages field, if the channel is configured to use it and the channelData version of the request (from version 2 onwards).

3. Finally, it calls the AuraBotAdapter method to send all the stored activities. In case the size of the response for any activity is larger than allowed by the Direct Line protocol, that must not exceed 256K characters, the response is ignored and a generic text explaining that there are too many results is returned to the user (errors:error.message.oversize).