162 lines
6.9 KiB
Markdown
162 lines
6.9 KiB
Markdown
This file isn't comprehensive, and is only quick overview. It's probably
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only useful in conjunction with skimming the appropriate headers
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(`application/ChatProtocol.h`, `application/ChatProtocolMessages.h`) and one of
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the included add-ons.
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This file's mostly here mostly here to clear up some behaviors that might not be
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immediately clear.
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# Add-on structure
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An add-on should export a few functions, and offer at least one class inheriting
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ChatProtocol.
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Each add-on must export the following functions;
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* `ChatProtocol* protocol_at(int32 i)`
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* `int32 protocol_count()`
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* `const char* signature()`
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* `const char* friendly_signature()`
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* `uint32 version()`
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A single add-on can support multiple protocols (the Purple add-on being the
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only current example of this)― but generally returning a "1" from
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`protocol_count()` and only returning a protocol from `protocol_at(0)` should be
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all you need.
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For a full description of the ChatProtocol object, look through
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`application/ChatProtocol.h`.
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Each ChatProtocol can be treated as either an account's instance, or solely for
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retrieving general metadata from the `Icon()`, `Signature()`, etc. methods― so
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please don't start the connection from the constructor.
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## Connection details
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A ChatProtocol's `UpdateSettings()` method should be used to receive settings
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from the program and declare a separate connection thread, but it generally
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shouldn't actually start the connection nor this thread.
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The connection should be started when the user's status is set to
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`STATUS_ONLINE`― and correspondingly, the connection should be paused or
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terminated when it is `STATUS_OFFLINE`. The user should be able to easily toggle
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the connection this way without any real consequences. If this is impossible,
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then the add-on can send `IM_PROTOCOL_DISABLE` just as the user-status is set
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to offline.
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`STATUS_OFFLINE` is for a momentary pause, i.e., the server is down or the user
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toggled the connection. The ChatProtocol will remain existent and active.
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If the status is set to offline by the protocol (and not the user!) Cardie will
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automatically attempt a reconnect after some time by trying to set the status
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to `STATUS_ONLINE`, which should toggle the connection.
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`IM_PROTOCOL_DISABLE` deletes the ChatProtocol, and should only be sent to the
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app when an irrecoverable error requiring user intervention has happened, i.e.,
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a configuration error, incorrect password, etc. If possible, it's preferable to
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send the user a notification (with `IM_ERROR`) telling them about the problem,
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just before sending `IM_PROTOCOL_DISABLE`.
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## Templates
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Each ChatProtocol has to provide UI "templates" for some important dialogues
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through the `SettingsTemplate()` method. In order of importance, they are
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"account", "create_room", "join_room", and "roster".
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"account" is used for accounts settings (seen by the user when configuring their
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account), "create_room"/"join_room" for creating or joining a room respectively,
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and "roster" for adding/editing a contact on the roster.
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Here's a shorter version of the XMPP add-on's "account" settings:
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``
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BMessage('IMst') {
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setting[0] = BMessage(0x0) {
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name = string("username")
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description = string("Jabber identifier:")
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error = string("You can't log into an account without a username.")
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type = int32(0x43535452 or 1129534546)
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}
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setting[1] = BMessage(0x0) {
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name = string("password")
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description = string("Password:")
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error = string("You can't log into an account without a password.")
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type = int32(0x43535452 or 1129534546)
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is_secret = bool(true)
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}
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setting[2] = BMessage(0x0) {
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name = string("server")
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description = string("Server:")
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error = string("You can't add an account without a server.")
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type = int32(0x43535452 or 1129534546)
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}
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}
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``
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The template is a BMessage with sub-messages named "setting", each with, at
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least, an internal "name" (the slot used by Cardie in the message parameter of
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`UpdateSettings()`), a user-friendly label ("description"), and the slot type
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in "type"― currently `B_INT32_TYPE`,` B_STRING_TYPE`, and `B_BOOL_TYPE` are
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accepted.
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By default, slots are not required, and it's accepted for the user to skip them.
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To make a slot required, put an error message into "error", warning the user
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to change their ways.
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Also optionally accepted are "is_secret" to determine if entered text is
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visible and "default" for a default value.
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The internal names of "settings" in these templates determine the values you
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should expect to receive for some messages from the app, like `IM_JOIN_ROOM`.
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# Dealing with messages
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For documentation of each API message, look through
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`application/ChatProtocolMessages.h`. For an example add-on, take a look at
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`protocols/xmpp/`― though it might not be simple, it is feature-complete.
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When messages are received from or to the app, it will generally be a message
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of IM_MESSAGE with an int32 named "im_what" containing the value.
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"im_what" values (along with comprehensive descriptions of their meanings)
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can be found in `application/ChatProtocolMessages.h`.
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## Slots
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Here are standard message slots that are frequently used or required, along
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with their meanings:
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* chat_id Unique identifier for a chatroom. (e.g., room address)
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* chat_name Display-name for a chatroom. Uniqueness not required.
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* user_id Unique identifier for a user. (e.g., JID, Matrix username)
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* user_name Nick-name or display name for a user. Uniqueness not required.
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* body Used for message-text, or explanation of an action (inviting or banning a user, etc)
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user_names and chat_names can be changed at will
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(through `IM_CONTACT_INFO`/`IM_USER_SET_NAME`/`IM_ROOM_PARTICIPANTS` and
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`IM_ROOM_DATA`/`IM_ROOM_NAME_SET` respectively), but user_ids and chat_ids
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cannot be changed.
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If you have to, you can "change" a chat or user's ID, by faking the user leaving
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and re-joining the room. This should be avoided if possible, since it breaks
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continuity a bit.
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# Joining a room
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The basic structure for joining a room should be like this, with each line being
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a subsequent response to the previous message:
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* Cardie (`IM_JOIN_ROOM`/`IM_CREATE_CHAT`) → Protocol
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* Protocol (`IM_ROOM_JOINED`/`IM_CHAT_CREATED`) → Cardie
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* Cardie (`IM_GET_ROOM_METADATA` & `IM_GET_ROOM_PARTICIPANTS`) → Protocol
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* Protocol (`IM_ROOM_METADATA` & `IM_ROOM_PARTICIPANTS`) → Cardie
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Preferably, `IM_ROOM_METADATA` and `IM_ROOM_PARTICIPANTS` should only be used as
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above (in response to a request from Cardie) since they are silent and don't
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explicitly tell the user what's happened― whereas messages like
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`IM_ROOM_PARTICIPANT_JOINED` and `IM_ROOM_SUBJECT_SET` will inform the user of
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the change.
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You can send `IM_ROOM_PARTICIPANTS` multiple times in a row― users
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not mentioned in subsequent mentions are not implicitly removed from the
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user-list, you must send a separate `IM_ROOM_PARTICIPANT_LEFT` for each parting
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user.
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