Offline instant messages on SQLite

OpenSim's offline-message module for standalones and grids, "Offline Message Module V2" (OpenSim/Addons/OfflineIM), keeps its messages through an IOfflineIMData storage plugin, and 0.9.3.0 ships that plugin for MySQL and PostgreSQL only. On a SQLite standalone the module cannot run: with StorageProvider = OpenSim.Data.SQLite.dll its service finds no storage class, throws "Could not find a storage interface in the given module", and because the exception comes out of a shared region module's Initialise, OpenSim stops at startup. The other module, OfflineMessageModule, needs an external web service (OfflineMessageURL, a PHP script).

This adds SQLiteOfflineIMData, a port of MySQLOfflineIMData: the same im_offline table, created by IM_Store.migrations the first time the handler opens the database, and the same generic-table access. The SQLite generic handler has no GetCount, so it is written here; DeleteOld uses datetime('now', '-14 days') where MySQL uses NOW() - INTERVAL 2 WEEK. Written 2026-09-27 for the ship plan's "offline IM on".

Apply to a fresh opensim-src

../sqlite-offlineim.diff creates both files (OpenSim/Data/SQLite/SQLiteOfflineIMData.cs and OpenSim/Data/SQLite/Resources/IM_Store.migrations). build/build_server.py applies it before Prebuild. By hand:

1. Apply the diff at the tree root (patch -p1 < sqlite-offlineim.diff, or git apply).
2. Re-run runprebuild (from cmd on Windows). prebuild.xml wildcards *.cs and Resources/*.migrations for this project, so the regenerated OpenSim.Data.SQLite.csproj includes both files.
3. Build OpenSim.Data.SQLite.csproj. The DLL is bin/OpenSim.Data.SQLite.dll; swap it in during a restart.

Deploy order on a running server: the DLL first, the config second. With the config below and an unpatched OpenSim.Data.SQLite.dll, OpenSim does not start.

Region config (bin/OpenSim.ini; config/paracosm.ini writes it)

[Messaging]
    OfflineMessageModule = "Offline Message Module V2"
    StorageProvider = OpenSim.Data.SQLite.dll
    ConnectionString = "URI=file:offlineim.db,version=3"

OfflineMessageURL stays unset (the service runs inside the simulator). Optional keys the service reads: MaxOfflineIMs (default 25 per recipient; the sender is told "Message not saved" past it), Realm (the table, default im_offline), ForwardOfflineGroupMessages (default true: group notices and invitations are kept too).

Tested (2026-09-27, offline; no OpenSim process was started)

Built with the whole series by build/build_server.py into a scratch folder; a test program in that bin/ drove the module and service through OpenSim's own classes:

• OfflineIMRegionModule.Initialise with the config above (the startup path): no exception.
• StoreMessage three times for one recipient, then a fourth refused with "Number of offline IMs has maxed out" at MaxOfflineIMs = 3.
• GetMessages returns the three intact (text, sender, UTF-8) and deletes them; a second call returns none.
• DeleteOld: a message aged 15 days is removed, a fresh one kept.
• The config as tools/make_config.py writes it, loaded by OpenSim's own ConfigurationLoader, starts the module and creates bin/offlineim.db.

Not tested: a message sent in a viewer to an avatar who is offline, and its delivery at that avatar's next login.