cadmium-docs-legacy/CPEs/proposed/CPE4 - Basic chats.md

CPE#4 - Basic chats

0. Table of content

• CPE#4 - Basic chats
  • 0. Table of content
  • 1. Introduction
  • 2. Requirements
  • 3. Message type identifiers
  • 4. Errors
    • 4.1. Error types
  • 5. Event types
    • 5.1. Media types
  • 6. Use cases
    • 6.1. Exchanging messages
    • 6.2. Exchanging media
    • 6.3. Read messages
    • 6.4. Typing message
    • 6.5. Message history API
      • 6.5.1. History retrieving
  • 7. Business Rules
    • 7.1. Typing message notification
    • 7.2. Message/Media ID
  • 8. JSON Schema
    • Event Entity
      • Content sections
    • Send message (urn:cadmium:chat:message)
      • Request
      • Response
    • Read message notification (urn:cadmium:chat:read)
      • Request
    • Edit message notification (urn:cadmium:chat:message:edit)
      • Request
    • Delete message notification (urn:cadmium:chat:message:delete)
      • Request
    • Sync history of user chats (urn:cadmium:chat:history:sync)
      • Request
      • Response

1. Introduction

This extension is intended for organizing chats between some entities.

2. Requirements

• Exchanging text messages
• Typing status
• Message reading
• Sharing files/media
• Forwards and replies to messages
• Stickers/GIF
• Message reactions

3. Message type identifiers

• urn:cadmium:chat:message - regular message
• urn:cadmium:chat:read - read message notification
• urn:cadmium:chat:typing - typing message notification
• urn:cadmium:chat:message:edit - edit message notification
• urn:cadmium:chat:message:delete - delete message notification
• urn:cadmium:chat:history:sync - sync history of user chats

4. Errors

• Ratelimit system: disabled
• Authorization: enabled

4.1. Error types

• urn:cadmium:chat:private:banned - Sending messages to user is prohibited, because he banned the sender of current message - in case if we send the message to user entity.

5. Event types

• urn:cadmium:chat:event:message - message with text and optional media

5.1. Media types

• urn:cadmium:chat:media:photo - a photo
• urn:cadmium:chat:media:audio - an audio or voice message
• urn:cadmium:chat:media:video - a video or rounded video message
• urn:cadmium:chat:media:file - any other file type
• urn:cadmium:chat:media:sticker - a sticker
• urn:cadmium:chat:media:gif - an animated GIF

6. Use cases

6.1. Exchanging messages

1. C1->S - Sending message:

   {
       "id": "abcd",
       "type": "urn:cadmium:chat:message",
       "to": ["@user2@cadmium.org"],
       "payload": {
           "type": "urn:cadmium:chat:event:message",
           "content": {
               "text": "hello world",
           }
       }
   }
   

   S->C1 - Successful response:

   {
       "id": "abcd",
       "type": "urn:cadmium:chat:message",
       "from": "cadmium.org",
       "ok": true,
       "payload": {
           "eventID": "3b5135a5-aff5-4396-a629-a254f383e82f",
           "originServerTimestamp": 1599327584
       }
   }
   

   S->C1 - Error response:

   {
       "id": "abcd",
       "type": "urn:cadmium:chat:message",
       "from": "cadmium.org",
       "ok": false,
       "payload": {
           "errID": "urn:cadmium:chat:private:banned",
           "errText": "The user has banned you"
       }
   }
   

2. S->C2:

   {
       "id": "abcd",
       "type": "urn:cadmium:chat:message",
       "from": "@user1@cadmium.im",
       "ok": true,
       "payload": {
           "eventID": "3b5135a5-aff5-4396-a629-a254f383e82f",
           "originServerTimestamp": 1599327584,
           "type": "urn:cadmium:chat:event:message",
           "content": {
               "text": "hello world",
           }
       }
   }
   

6.2. Exchanging media

1. Upload the media to Content Service (explanation out of scope of this document)
2. Send message containing the metadata of uploaded media:

C1->S:

 {
     "id": "abcd",
     "type": "urn:cadmium:chat:message",
     "to": ["@user2@cadmium.im"],
     "payload": {
         "type": "urn:cadmium:chat:event:message",
         "content": {
             "text": "",
             "media": [
                 {
                     "id": "4a771ac1-f0b2-4a4a-9700-f2a26fa2bb67@content.cadmium.im"
                 }
             ]
         }
         
     }
 }

S->C1:

{
     "id": "abcd",
     "type": "urn:cadmium:chat:message",
     "from": "cadmium.im",
     "ok": true,
     "payload": {
         "messageID": "7a1b9a72-1677-4476-9b22-ef7fdbcff52e",
         "originServerTimestamp": 1599329232
     }
 }

Note: The Cadmium server will validate media ID which was provided by client. If it doesn't exist or invalid, server will respond with corresponding error.

3. Receive message with media on other side:

S->C2:

{
     "id": "defg",
     "type": "urn:cadmium:chat:message",
     "from": "@user1@cadmium.im",
     "ok": true,
     "payload": {
         "messageID": "7a1b9a72-1677-4476-9b22-ef7fdbcff52e",
         "originServerTimestamp": 1599329232,
         "type": "urn:cadmium:chat:event:message",
         "content": {
             "text": "",
             "media": [
                 {
                     "id": "4a771ac1-f0b2-4a4a-9700-f2a26fa2bb67@content.cadmium.im",
                     "type": "urn:cadmium:chat:media:photo",
                     "attrs": {
                         "width": 512,
                         "height": 512 
                     },
                     "size": 96413, // 96kb
                 }
             ]
         }
     }
 }

6.3. Read messages

1. Read message

   {
       "id": "abcd",
       "type": "urn:cadmium:chat:read",
       "to": ["@user1@cadmium.org"],
       "payload": {
           "messageID": "7a1b9a72-1677-4476-9b22-ef7fdbcff52e",
       }
   }
   

   Response:

   {
       "id": "abcd",
       "type": "urn:cadmium:chat:read",
       "from": "cadmium.im",
       "ok": true,
       "payload": {}
   }
   

2. Receive notification about message reading on other side:

   {
       "id": "defg",
       "type": "urn:cadmium:chat:read",
       "from": "@user2@cadmium.im",
       "ok": true,
       "payload": {
           "messageID": "7a1b9a72-1677-4476-9b22-ef7fdbcff52e"
       }
   }
   

6.4. Typing message

1. Typing message

   {
       "id": "abcd",
       "type": "urn:cadmium:chat:typing",
       "to": ["@user1@cadmium.org"],
   }
   

2. Receive notification about typing message on other side:

   {
       "id": "defg",
       "type": "urn:cadmium:chat:typing",
       "from": "@user2@cadmium.im",
       "ok": true
   }
   

6.5. Message history API

6.5.1. History retrieving

7. Business Rules

7.1. Typing message notification

• Client sends typing notification message every second when he is typing. If there is no notifications about typing more than one second then consider that user is stopped the typing.

7.2. Message/Media ID

• This is typically Federated Entity ID of message/media (as described and reserved in core specs) which was stored in server's database/content service storage.

8. JSON Schema

Event Entity

interface Event {
    id: EntityID; // the message id (stored in chat timeline) - not required when sending
    type: string; // the type of event
    originServerTimestamp: number; // unix timestamp of received message on the origin server (not required when sending)
    content: Content; // the payload of message (depends on type)
}

interface Content {}

Content sections

• urn:cadmium:chat:events:types:message:

  interface MessageContent : Content {
      text: string; // the text (body) of message
      mentioned?: boolean; // is current entity was mentioned in this message
      media?: Media[]; // media content
  	forwardedFrom?: EntityID | string; // entity from which this message was forwarded (may be hidden, so instead client need to show the display name of entity)
  	replyTo?: EntityID; // message id to which this message is replying
  }
  
  interface Media {
      id: string; // media ID
      type: string; // type of media
      size: number; // size of media in bytes
      fileName?: string; // filename of media (with optional extension by dot)
      attrs: MediaAttrs; // media payload (additional attributes)
  }
  
  // Media attributes definitions
  
  interface MediaAttrs {}
  
  // urn:cadmium:chats:media:audio
  interface AudioAttrs : MediaAttrs {
      voice: bool; // whether it is voice message
      duration: number; // duration of audio
      title?: string; // audio title
      artist?: string; // audio artist
      voiceWaveForm?: []byte; // voice wave form
  }
  
  // urn:cadmium:chats:media:sticker
  interface StickerAttrs : MediaAttrs {
      associatedEmoji: string; // the associated emoji with this 
      stickerSetID: string; // id of sticker set which is associated with this sticker
      isAnimated: boolean; // is client need to animate this sticker
  }
  
  // urn:cadmium:chats:media:video
  interface VideoAttrs : MediaAttrs {
      isVideoMessage: bool; // is this a rounded video message
      duration: number; // duration of video
      width: number; // width of video
      height: number; // height of video
  }
  
  // urn:cadmium:chats:media:photo
  interface PhotoAttrs : MeditAttrs {
      width: number; // width of photo
      height: number; // height of photo
  }
  
  interface GeolocationAttrs : MediaAttrs {
  	lat: number; // the GPS latitude
      lon: number; // the GPS longitude
  }
  

Send message (urn:cadmium:chat:message)

Request

interface SendMessageReq {
    type: string;
	content: Content;
}

Response

interface SendMessageResponsePayload {
    id: EntityID; // the message id (stored in chat timeline)
    originServerTimestamp: number; // unix timestamp of sent message on the origin server
}

Read message notification (urn:cadmium:chat:read)

Request

interface ReadMessageNotif {
    eventID: EntityID; // the read message id
}

Edit message notification (urn:cadmium:chat:message:edit)

Request

interface EditMessageNotif {
    eventID: EntityID; // edited message id
    updatedContent: Content; // new content of message
}

Delete message notification (urn:cadmium:chat:message:delete)

Request

interface DeleteMessageNotif {
    eventID: EntityID; // deleted message id
}

Sync history of user chats (urn:cadmium:chat:history:sync)

Request

interface ChatsHistorySyncReq {
    since: EntityID; // event from which need to sync the history
	limit: number; // count of events which need to return
	includeChatInfo: boolean; // include chat/user info mentioned in events into response
	chatID?: EntityID; // get history of specific chat
	direction?: SyncDirection; // in case of getting history of specific chat
}

enum SyncDirection {
	Up = "UP", // previous events from 'since' event
	Down = "DOWN" // next events from 'since' event
}

Response

interface ChatsHistorySyncResp {
    nextBatch: EntityID; // next 'since' value for client
	events: Event[]; // synced events
	chats?: Chat[]; // chats mentioned in events
	users?: User[]; // users mentioned in events
}

interface Event {
	eventID: EntityID; // event id in timeline
	from: EntityID; // event author
	chatID: EntityID; // related chat id
	type: string; // type of event
	timestamp: number; // origin timestamp of event
	originServer: EntityID; // origin server author of event
	content: Content; // content of event
}