:title: LADI Session Handler
:docinfo: private-head,private-header
:keywords: LADI, JACK, jack-audio-connection-kit, session management

= LADISH

LADI Session Handler or simply ladish is a session management system
for https://jackaudio.org[JACK] applications on https://kernel.org/[GNU/Linux].
Its aim is to allow you to have many different audio programs running
at once, to save their setup, close them down and then easily reload
the setup at some other time. ladish doesn\'t deal with any kind of
audio or MIDI data itself; it just runs programs, deals with
saving/loading (arbitrary) data and connects JACK ports together.

The LADISH graphical interface (GTK+ based reference front end)
image:https://static.lwn.net/images/2013/audio-session/1-gladish-reteo.png["gladish screenshot", link="https://lwn.net/Articles/533594/", width="100%"]

The Claudia LADISH front end (Python + Qt based)
image:https://static.lwn.net/images/2013/audio-session/2-claudia.png["Claudia screenshot", link="https://lwn.net/Articles/533594/", width="100%"]

Features:

 * Save and restore sets of JACK (audio and MIDI) enabled
   applications.
 * Subgraph management, the Studio & Rooms concept.
   Provide JACK clients with virtual hardware ports, so projects can
   be transferred (or backups restored) between computers running
   different hardware and backups. 
   Allows to decouple projects (loaded in a Room) from
   hardware audio IO used in particular Studio.
   A virtual jack-multicore cable connects room IO ports
   to hardware IO ports.
 * Don't require session handling library to be used. There is no need
   of such library for restoring connections between JACK clients.
   LADISH is able to manage JACK apps that don\'t link to liblash (or liblo).
   This is known as L0 (level zero) in LADISH.
 * Seamless handling of apps that use ALSA sequencer ports.
   This is achieved by use of a2jmidid and libalsapid.so.
   The former creates jack-midi ports for the alsa sequencer ones.
   The latter reports the alsa application process ID to ladishd,
   so that ladishd can associate the a2jmidid-created ports with application.
 * Flow canvas based GUI. Positions of elements on the canvas are
   saved/restored.
 * Allow clients to use external storage to save their state. This
   includes storing internal state to non-filesystem place like memory
   of a hardware synth. This also includes storing client internal
   state (client project data) in a way that is not directly bound to
   ladish project.

Among project future goals are:

 * Support for pipewire setups (in addition to JACK1 and JACK2)
 * List of available JACK applications.
 * Hierarchical and/or tag-based organization of projects.
 * Support for applications that create more than one jack client per process
 * Support for applications that create use more than one jack client process
 * https://ladish.org/nsm-proto.html[Non Session Manager protocol] support
 * https://new-session-manager.jackaudio.org/api/index.html[New Session Manager protocol] support
 * Collaborate with the X11 window manager so window properties like
   window position, virtual desktop and screen (multimonitor) are
   saved/restored.
 * Distributed studio - network connected computers. Netjack
   configuration is part of the studio and thus is saved/restored.
   Saving/restoring state in multi-machine network
 * Ability to move entire sessions between computers,
   or post sessions on the Internet for download.
   Import/export operations, as opposed to save/load. Save/load
   operate in current system and may cause saving data outside of
   project itself (external storage). Import/export uses/produces
   "tarball" suitable for transferring session data over network to
   other computer or storing it in a backup archive.
 * Session versioning via Git

Tarballs:

 * https://dl.ladish.org/ladish/

GIT repositories:

 * https://gitea.ladish.org/LADI/ladish[Upstream development GIT repository] +
   Self-hosted upstream
 * https://github.com/LADI/ladish.git[Primary backup GIT repository at github.com] +
   Cloud hosted
 * https://repo.or.cz/ladish.git[Secondary backup GIT repository at repo.or.cz] +
   Cloud hosted

LADI Session Handler was forked from the
https://lac.linuxaudio.org/2009/cdm/Thursday/02_Alasuutari/02.pdf[D-Bus-ified LASH project].
Things that LADISH can do but LASH (D-Bus-ified or not) cannot:

 * Subgraph management, the Studio & Rooms concept.
   Allows to decouple projects (loaded in a Room) from
   hardware audio IO used in particular Studio.
   A virtual jack-multicore cable connects room IO ports
   to hardware IO ports.
 * Don't require session handling library to be used. There is no need
   of such library for restoring connections between JACK clients.
   LADISH is able to manage JACK apps that don\'t link to liblash (or liblo).
   This is known as L0 (level zero) in LADISH.
 * Seamless handling of apps that use ALSA sequencer ports.
   This is achieved by use of a2jmidid and libalsapid.so.
   The former creates jack-midi ports for the alsa sequencer ones.
   The latter reports the alsa application process ID to ladishd,
   so that ladishd can associate the a2jmidid-created ports with application.

See also:

 * https://gitea.ladish.org/LADI/ladish[LADI/ladish at Gitea]
 * https://github.com/LADI/[LADI at GitHub]
 * https://jackdbus.ladish.org/[jackdbus]
 * https://lac.linuxaudio.org/2009/cdm/Thursday/02_Alasuutari/02.pdf[Juuso ALASUUTARI, LASH Audio Session Handler: Past, Present, and Future]

For related discussions, you are invited to join
https://libera.chat/[Libera.Chat] channel #ladi
