MusicDB Websocket Server

This is the main module to run the MusicDB Server.

To start and run the server, the following sequence of function calls is necessary:

Initialize(mdbconfig, musicdatabase)
StartWebSocketServer()
Run()

This module maintain global instances of the following classes. Those objects can be used inside the thread the server runs. Usually the main thread. Using these objects saves a lot of memory. If the server is not started, the objects are all None.

• musicdb.lib.db.musicdb.MusicDatabase as database

• musicdb.mdbapi.mise.MusicDBMicroSearchEngine as mise

• musicdb.lib.cfg.musicdb.MusicDBConfig as cfg

musicdb.mdbapi.server.Initialize(configobj, databaseobj)

This function initializes the whole server. It initializes lots of global objects that get shared between multiple connections.

The following things happen when this method gets called:

1. Assign the configobj and databaseobj to global variables cfg and database to share them between multiple connections

2. Seed Python’s random number generator

3. Instantiate a global musicdb.mdbapi.mise.MusicDBMicroSearchEngine() object

4. Starting the upload, integration and import management via musicdb.taskmanagement.managementthread.StartTaskManagementThread()

5. Start the Audio Streaming Thread via musicdb.mdbapi.audiostream.StartAudioStreamingThread() (see Audio Streaming Server for details)

6. Start the Video Streaming Thread via musicdb.mdbapi.videostream.StartVideoStreamingThread() (see Audio Streaming Server for details)

7. Update MiSE cache via musicdb.mdbapi.mise.MusicDBMicroSearchEngine.UpdateCache()

Parameters

• configobj – MusicDBConfig that gets shared between connections

• databaseobj – MusicDatabase that gets shared between connections

Returns

None

Raises

• TypeError – When configobj is not of type MusicDBConfig

• TypeError – When databaseobj is not of type MusicDatabase

musicdb.mdbapi.server.Run()

This is the servers main loop.

Inside the loop all MusicDB Websocket Server events get handled by calling musicdb.lib.ws.server.MusicDBWebSocketServer.HandleEvents(). When a shutdown gets triggered the Shutdown() function gets called and the server stops.

The Shutdown() gets also called the user presses Ctrl-C This leads to a regular shutdown.

In as an exception occurs the Shutdown() gets called, too. In this case the exit-code will be 1.

musicdb.mdbapi.server.SIGTERM_Handler()

This function is the handler for the system signal TERM. It signals the server to shut down.

musicdb.mdbapi.server.Shutdown()

This function stops the server and all its dependent threads.

The following things happen when this function gets called:

1. Stopping task management via musicdb.taskmanagement.managementthread.StopTaskManagementThread()

2. Stop the Audio Streaming Thread via musicdb.mdbapi.audiostream.StopAudioStreamingThread()

3. Stop the Video Streaming Thread via musicdb.mdbapi.videostream.StopVideoStreamingThread()

4. Stop the websocket server

At the end, the program gets terminated. So, this function gets never left.

The exit code will be 0 if this was a regular shutdown. If the shutdown got forced, for example due to a critical error, the exit code is 1.

This function should also be called when Initialize() fails or when it raises an exception.

musicdb.mdbapi.server.SignalHandler(signum, stack)

This is the general signal handle for the MusicDB Server. This function reacts on system signals and calls the handler of a specific signal.

Parameters

• signum – signal number

• stack – current stack frame

Returns: Nothing

musicdb.mdbapi.server.StartWebSocketServer()

This function creates and starts the actual MusicDB Websocket Server.

Returns

True on success, otherwise False

musicdb.mdbapi.server.UpdateCaches()

This function handles the signal to refresh the server cache. Its task is to trigger updating the servers cache and to inform the clients to update.

On server side:

• The MiSE Cache gets updated by calling musicdb.mdbapi.mise.MusicDBMicroSearchEngine.UpdateCache()

To inform the clients a broadcast packet get sent with the following content: {method:"broadcast", fncname:"sys:refresh", fncsig:"UpdateCaches", arguments:null, pass:null}

Example

if(fnc == "sys:refresh" && sig == "UpdateCaches") {
    MusicDB_Request("GetTags", "UpdateTagsCache");                  // Update tag cache
    MusicDB_Request("GetFilteredArtistsWithAlbums", "ShowArtists"); // Update artist view
}