62 lines
4 KiB
Markdown
62 lines
4 KiB
Markdown
Friendica Message Flow
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===
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This page documents some of the details of how messages get from one person to another in the Friendica network.
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There are multiple paths, using multiple protocols and message formats.
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Those attempting to understand these message flows should become familiar with (at the minimum) the [DFRN protocol document](https://github.com/friendica/friendica/blob/stable/spec/dfrn2.pdf) and the message passing elements of the OStatus stack (salmon and Pubsubhubbub).
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Most message passing involves the file include/items.php, which has functions for several feed-related import/export activities.
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When a message is posted, all immediate deliveries to all networks are made using include/notifier.php, which chooses how (and to whom) to deliver the message.
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This file also invokes the local side of all deliveries including DFRN-notify.
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mod/dfrn_notify.php handles the remote side of DFRN-notify.
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Local feeds are generated by mod/dfrn_poll.php - which also handles the remote side of DFRN-poll protocol.
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Salmon notifications arrive via mod/salmon.php.
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Push (pubsubhubbub) feeds arrive via mod/pubsub.php
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DFRN-poll feed imports arrive via src/Worker/OnePoll.php as a scheduled task, this implements the local side of the DFRN-poll protocol.
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### Scenario #1. Bob posts a public status message
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This is a public message with no conversation members so no private transport is used.
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There are two paths it can take - as a bbcode path to DFRN clients, and converted to HTML with the server's PuSH (pubsubhubbub) hubs notified.
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When a PuSH hub is operational, dfrn-poll clients prefer to receive their information through the PuSH channel.
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They will fall back on a daily poll in case the hub has delivery issues (this is quite common when using the default Google reference hub).
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If there is no specified hub or hubs, DFRN clients will poll at a configurable (per-contact) rate at up to 5-minute intervals.
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Feeds retrieved via dfrn-poll are bbcode and may also contain private conversations which the worker has permissions to see.
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### Scenario #2. Jack replies to Bob's public message. Jack is on the Friendica/DFRN network.
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Jack uses dfrn-notify to send a direct reply to Bob.
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Bob then creates a feed of the conversation and sends it to everybody involved in the conversation using dfrn-notify.
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PuSH hubs are notified that new content is available.
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The hub or hubs will then retrieve the latest feed and transmit it to all hub subscribers (which may be on different networks).
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### Scenario #3. Mary replies to Bob's public message. Mary is on the Friendica/DFRN network.
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Mary uses dfrn-notify to send a direct reply to Bob.
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Bob then creates a feed of the conversation and sends it to everybody involved in the conversation (excluding himself, the conversation is now sent to both Jack and Mary).
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Messages are sent using dfrn-notify.
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Push hubs are also notified that new content is available.
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The hub or hubs will then retrieve the latest feed and transmit it to all hub subscribers (which may be on different networks).
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### Scenario #4. William replies to Bob's public message. William is on the OStatus network.
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William uses salmon to notify Bob of the reply.
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Content is html embedded in salmon magic envelope.
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Bob then creates a feed of the conversation and sends it to all Friendica participants involved in the conversation using dfrn-notify (excluding himself, the conversation is sent to both Jack and Mary).
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Push hubs are notified that new content is available.
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The hub or hubs will then retrieve the latest feed and transmit it to all hub subscribers (which may be on different networks).
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### Scenario #5. Bob posts a private message to Mary and Jack.
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Message is delivered immediately to Mary and Jack using dfrn_notify.
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Public hubs are not notified.
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Requeueing is attempted in case of timeout.
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Replies follow the same flow as the public replies except that hubs are not notified and message is never made available in the public feed.
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The entire conversation is also made available to Mary and Jack (and nobody else) through their dfrn-poll personalised feed.
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