11.2 Term map

Quick glossary of Kamailio-specific terms used throughout the handbook. SIP-protocol terms (UAC, UAS, INVITE, etc.) are taken as known from RFC 3261.

Term	Means
AOR	Address Of Record — the SIP identity (alice@example.com) under which contacts are registered.
apiban	Community feed of known-bad SIP source IPs (apiban.org). Not a Kamailio core module — consumed by pulling its JSON into an htable, or by an external client that updates ipset/iptables.
AVP	Attribute-Value Pair — a script-accessible named variable, scope-bound to a transaction or branch. Survives async suspend/resume.
branch	One destination within a forked transaction. Each branch has its own outgoing buffer, lump set, retransmission state.
BINRPC	Binary RPC protocol over Unix socket. The default transport for kamcmd.
cell	A tm transaction record in shm. Holds branches, timers, refcount, hooks.
cfg DSL	The configuration language: kamailio.cfg. Pre-compiled to an AST at startup, executed per message.
child_init()	Module hook that runs once per worker after fork. Where per-process resources (interpreter state, DB connections) get set up.
contact	A SIP Contact URI, a binding from an AOR to a specific endpoint.
dialog	A call-level state record spanning multiple transactions. Maintained by the dialog module.
dispatcher set	A named, numbered group of destinations with a selection algorithm and probing config.
dmq	Distributed Message Queue. The peer-to-peer replication mesh across multiple Kamailio instances.
FFI	Foreign Function Interface — the C-to-script bridge used by KEMI to dispatch into Lua/Python/JS/Ruby interpreters.
htable	Generic shm hash table, the "poor man's Redis."
ipban	The transient htable shipped in the stock kamailio.cfg. Holds greylisted source IPs (populated when pike flags a flooder, expired via autoexpire); checked early in request_route to drop offenders.
KEMI	Kamailio Embedded Interface. The mechanism for writing routing logic in Lua, Python, JS, or Ruby.
KSR.*	The global namespace exposed in KEMI scripts. KSR.tm.t_relay() calls the registered C function.
lump	A queued message mutation (add or delete bytes at an offset). Applied in one pass at send time.
mod_init()	Module hook that runs once in the main process, before fork. Where shm is allocated and RPC commands are registered.
pike	Module that tracks per-source-IP request rate with a per-source counter over a sampling window in shm and flags floods.
pkg	Per-worker private memory heap. Lifetime is one message; not visible to other workers.
pseudo-variable	A script-side getter/setter on the sip_msg or runtime state. Names start with $ — $ru, $tu, $hdr(X), $var(x), $shv(x).
rank	Integer ID of a forked worker process. Used for RNG seeding, timer-slot selection, log disambiguation.
RPC	Remote Procedure Call. Kamailio's runtime introspection/control API. Exposed via BINRPC and JSON-RPC.
secfilter	Module that blacklists/whitelists SIP header content (User-Agent, From, To, domain, dst) and known SQL-injection patterns.
sip_msg	The C struct holding a parsed message: original buffer, header list, body, lump lists, flags. Lives in pkg, one per worker per message.
shm	Shared memory — one mmap()'d region accessible from every worker. Lifetime spans messages and workers.
$shv	Shared variable. A named global in shm.
$sht	htable accessor. $sht(table=>key) reads/writes an entry.
t_continue()	Resume a previously-suspended transaction with a result.
t_relay()	Forward a request statefully via tm. Creates the transaction.
t_suspend()	Pause the current transaction's progress, release the worker, allow asynchronous resume later.
tm	Transaction Module. Tracks SIP transactions in shm, manages retransmission and forking.
topos	Topology hiding module. Rewrites messages so the proxy is invisible to endpoints.
transaction	A SIP request plus all its responses, including retransmissions. The unit of state in tm.
usrloc	User Location module. The registrar's contact cache, backed optionally by DB.
WAIT timer	Per-transaction timer that lingers after a final response, absorbing retransmissions before cleaning up.
wheel (timer)	Time-bucketed array used by tm's timer process. O(1) to schedule, O(K) per tick where K is expirations.

Notation conventions used in code samples

• something() — module function callable from cfg.
• $xx or $xx(arg) — pseudo-variable, evaluated against the current sip_msg.
• kamcmd <method> — BINRPC command invoked from the host shell.
• event_route[<name>] — a runtime hook, dispatched by the runtime, not by an inbound message.
• KSR.<module>.<function> — KEMI-side call into a registered C function.

Where each concept is covered

If you're confused about…	See
Why there are so many processes	Chapter 2.1
Why $var doesn't survive across messages	Chapter 2.1, 2.2
Why remove_hf doesn't immediately remove the header	Chapter 3.3
Why kamailio.cfg can't be reloaded	Chapter 2.4
Why Lua globals aren't shared between workers	Chapter 5.3
Why dispatcher.reload mid-call can shift stickiness	Chapter 8.4
Why dmq is "eventually consistent"	Chapter 8.5
Why kamcmd is short but capable	Chapter 7.2

This concludes the handbook. The next time something in production looks strange, the path is: check kamcmd (chapter 7.2), read the relevant chapter on what's involved, and if needed, drop into the asipto devel-guide for the implementation details that this handbook deliberately summarised.

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