---

summary: Cache presence incoming presence

...

Introduction

============

This module stores presence from users contact even when they are

offline, so that the client can see who is online faster when they sign

in, and won't have to wait for remote servers to reply.

Note that in its current form, the number of presence stanzas sent to a

client is doubled, as the client would get both the cached stanzas and

replies to presence probes. Also see [mod\_throttle\_presence].

By default, only binary (online or offline) state is stored. It can

optionally store the full presence but this requires much more memory.

Configuration

=============

Just enable the module.

    modules_enabled = {

        -- more modules

        "presence_cache";

    }

Advanced configuration

======================

To enable full stanza caching:

    presence_cache_full = false

TODO

====

-   Deduplication, i.e don's send stanzas that are identical to the last

    seen.

-   Cache invalidation or expiry, eg if a remote server goes down or is

    gone a long time.

-   Sending probes at some interval to keep the cache reasonably fresh.