zulip-xmpp/pm/xmpp-lib-decision.org

0.1.3 XMPP Event Model and Library Choice

• initial research and recommendation
• minimum viable raw xmpp
• event model we actually need
• recommendation
• summary

initial research and recommendation

Slixmpp is an MIT-licensed XMPP library for Python 3.11+.

It is a fork of SleekXMPP and uses Rust for some performance-sensitive modules. In practice that means:

• Python app, not Rust app
• usually installable via PyPI wheels
• if wheels are unavailable, cargo may be needed to build the extension module
• maintained enough to be a sane v0 choice

For this bridge, slixmpp is the best MVP pick.

minimum viable raw xmpp

If we do not use a library, we would need to implement the XMPP client plumbing ourselves:

• TCP + XML stream handling
• SASL auth
• TLS
• stanza parsing/serialization
• MUC join/leave semantics
• keepalive/reconnect handling
• duplicate/self-message suppression rules on top

Pros:

• maximum control
• fewer dependencies
• easier to trim down to exactly what we need

Cons:

• you are writing a mini XMPP client anyway
• more edge cases
• slower to reach a reliable relay
• easier to get auth/reconnect/MUC details subtly wrong

For v0, that trade is not worth it.

event model we actually need

event	use
connect/auth	establish session
self-presence	confirm MUC join before relaying
groupchat message	relay input
presence join/part	ignore or log only
subject/topic change	optional log only
disconnect/error	reconnect handling

recommendation

Use slixmpp for the XMPP side.

Why:

• it covers the protocol plumbing we do not want to hand-roll
• it is a straightforward bot/daemon fit
• it lets us focus on bridge behavior, not XML socket mechanics
• it is good enough for a single-room relay MVP

summary

Use slixmpp unless we deliberately choose to prototype a raw XMPP client first.

The bridge only needs a narrow slice of XMPP. Slixmpp gives us that slice without forcing us to reinvent session management, MUC join semantics, or reconnect logic.