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# LASH Audio Session Handler

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# 1. Introduction

LASH stands for LASH Audio Session Handler. It is a session management system for audio applications on GNU/Linux. It understands the JACK low latency audio API and the ALSA MIDI sequencer interface. The system is comprised of a server program, `lashd`, an application library, `liblash`, and a control program - either the command-line `lash_control` or the GTK `lash_panel`. The server and clients communicate over TCP sockets. There are three kinds of clients: normal clients (audio applications), user interfaces for the server, and connection patchbays.

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## 1.1 Nomenclature

In order to describe the system, we should introduce some terminology. First of all, the server is the `lashd` server program, an omni-present marshaller and database for storing arbitrary application data. The library is the ``liblash'` shared library. It contains all the functions that an application uses to communicate with the server and take part in the system. Such an application is called a client.

The server deals with things in terms of collections of clients, called projects. A project has a unique string name, a current directory and a list of clients that are in that project. The server can have one client that is a server interface that allows the user to control the server. There are two server interface included with the system, the `lash_control` command-line interface, and the `lash_panel` GTK interface.

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# 2. Copying LASH

LASH is distributed under the GNU General Public License. A copy of the license text is provided in the file ``COPYING'` along with the software source code, or you can get a copy by writing to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

In plain english, the GPL basically restricts you from restricting other people's use of the LASH source code (ie, all of LASH), and any additions you make to the code, including linking with the LASH library. If you use code from this software, your software must be relased under the GPL. If you modify this software and release it, your modifications must be released under the GPL. If you release software linked against the LASH library, your software must be released under the GPL.

Note that this in no way restricts those people who want to release non-free LASH clients. LASH operates using a well defined protocol over TCP sockets. The high-level protocol is described within this document and the lower-level bit-wise protocol can be garnered from the source itself.

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# 3. Installation

This chapter describes how to get LASH installed on your system.

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## 3.1 Dependencies

LASH depends on the ALSA library, the JACK library, a unique ID library called libuuid and the XML library libxml2. You need these installed before attempting to install LASH.

ALSA is available from http://www.alsa-project.org/.

JACK is available from http://jackit.sf.net/.

The libuuid library is included with the ubiquitous e2fsprogs package, but if this is not installed on your system, it is available from http://e2fsprogs.sf.net/. The libxml2 library is available from http://www.xmlsoft.org/.

The LASH Control client depends on the GNU Readline library, available from ftp://ftp.gnu.org/pub/gnu/readline/.

The LASH GTK Test Client, LASH Save Button, and LASH Panel all depend on the GTK+ 2 toolkit, available from ftp://ftp.gtk.org/pub/gtk/v2.0/. The LASH Synth client has an optional GUI which also uses the GTK+ 2 toolkit.

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## 3.2 Installation

First off, you need to download the package. It is available from the LASH webpage, http://www.nongnu.org/lash. After you have downloaded it, unpack the tarball into a directory using `tar -xzf /where/ever/you/put/lash-0.6.0.tar.gz` and change into the source directory with `cd lash-0.6.0`.

The package uses the GNU autotools for configuration and makefile creation. In order to install the package, you must complete three steps: configuration; building; and installing.

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### 3.2.1 Configuration

To configure the package, there is a shell script named ``configure'` in the top source directory. It is a standard GNU autoconf configure script, and so accepts the standard GNU configuration options (such as ``--prefix'`, ``--datadir'`, etc.) To run it type `./configure` and add any options. The non-standard options that the script recognises are described below. Running the script with the ``--help'` option will also provide a quick summary of the recognised options.

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#### 3.2.1.1 Configure script options

``--disable-gtk2 Prevents the configure script from'`

  checking for the presence of the GTK+ 2 toolkit and disables the building of any code that relies on it.

``--enable-debug Causes the library, server and clients to be built'`

  with debugging output. This is not very useful and only recommended for developers working on the LASH code itself.

``--with-default-dir=DIR Specifies the default directory, relative'`

  to \$HOME under which the server will create new project directories. Without this option, the value defaults to ``audio-projects'`.

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### 3.2.2 Building

To build the package, simply type `make` in the top source directory. This will build the server, the library and the clients that are compatible with the resources found by the configure script.

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### 3.2.3 Installing

To install the package, type `make install` in the top source directory. By default the package installation prefix is ``/usr/local'` but the ``--prefix'` option to the configure script will change this. The `lashd` server and the clients that were built are installed in ``prefix/bin'`. The `liblash` client library is installed in ``prefix/lib'`. The C header files for the client library are installed under ``prefix/include'`. This manual is installed under ``prefix/info'`.

With `make install`, the package is installed with debugging symbols in the object files. To save space, you can install with `make install-strip` to install the object files without debugging symbols.

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# 4. Server

The LASH server is called ``lashd'`.

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# 5. Server interface

For a command line interface, run the command `lashd_control`. There is a `help` command.

For a graphical interface, run the command `lash_panel`. It should be relatively self-explanatory.

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# 6. Client reference

This chapter provides a programming guide and library reference for programmers of LASH clients.

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## 6.1 Operational overview

In this section we give an overview of how the LASH system operates, describing the server and client objects and operations that make it work. The `lashd` server must be running in order for clients to participate in the system; clients cannot interoperate soley between themselves. The server maintains a list of connected clients and a list of projects with which these clients are associated.

The server and clients exchange events and configs over their connections. There is one, and only one, bi-directional connection between a client and the server. The transport for this connection is currently TCP.

An event is a very simple object having two relevant properties: a type and an optional arbitrary character string. The type defines what the event means to the recipient, and the string allows additional information to be included with it. For example, if a client wishes the server to save the current project, it sends a `LASH_Save` event to the server. While saving the project, the server may wish to tell a client to save its data in a certain directory. To so, it sends a `LASH_Save_File` event to the client with a string containing the name of a directory into which the client should save its data files.

Clients can save data on the server if they wish. To do this, the client declares that it wants to save data on the server when it initialises the server connection and then later sends one or more configs to the server. A config is also a very simple object. It has a client-unique character string key, and a value of arbitrary size and type (well, almost arbitrary; its size must be able to be described by a `uint32_t` integer due to byte-order conversions done when sending data over the network.)

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### 6.1.1 Session example

In this section we will examine a typical session in some detail, describing the server and client operations that take place. In the session, the server is started, a number of clients connect, the session is saved and then restored.

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#### 6.1.1.1 Starting up the server

Before all else, the user starts the server. It starts up and begins listening for connections from clients. It doesn't do much else.

To keep track of what is happening with LASH, the user can run the `lash_panel` program (though this is not necessary, and it can be started later at any time).

Unless the environment variable `LASH_NO_START_SERVER` is set any LASH client will automatically start the server if one isn't already running. Doing this you can simply run applications normally (e.g. from a terminal or your Applications menu) and have LASH automatically work without having to remember to start the server manually.

Starting the server can also be disabled by specifying the `--lash-no-start-server` option on the client's command line.

If you're using a Bourne compatible shell like `bash` (if you don't know, you probably are) you can disable auto-start with the following command:

`export LASH_NO_START_SERVER=1`

Some applications may also choose themselves whether to start the server (or have a configurable option), however risabling the automatic start (by any method) is not recommended if you want to gain the benefits of LASH. With auto launching enabled you don't need to worry about LASH until you actually want to save a session.

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#### 6.1.1.2 A client connection

The user then starts a JACK client program. It opens a connection to the server and provides it with all information that the server will need to run the application again. This information includes: the current directory that the user was in when they ran the program, the command line that started the application and the class of the client (a character string that the client application provides the initialisation routine that will never change over all initialisations.)

With this information is included a set of flags that describe the client to the server. This particular client saves data to files and wants the server to tell it where to save files when the project is saved, so it has the `LASH_Config_File` flag set.

The client library starts two threads for communication with the server, one for sending data and the other for recieving. It also sends, along with the client supplied data, a number of parameters that were extracted from the client's command line options before it checked them. This optionally includes the name of the project that the client should initially be associated with and a 128-bit, world-unique identifier for this particular client instance (the LASH ID.)

Server-side, the server wakes up to the fact that a new connection has arrived and immediately adds it to a list of open connections and then goes back to waiting. When the client sends the requisite information, the server looks at it and decides what to do with the client. This client has not requested a specific project to which it should be connected. However, there are no existing projects so the server creates a new project with the name ``project-1'` in the directory ``/home/user/audio-projects/project-1'` (assuming the user didn't specify a different default directory when running configure.) It also generates a new LASH ID for the client. It then adds the client to the new project and goes back to listening.

If the user has the `lash_panel` client running, the new project will appear as a tab with the title ``project-1'`, and the new client will appear in the client list for that project.

The client then connects up to the JACK server and, after having done this, sends a `LASH_Jack_Client_Name` event to the server with the name that it registered to JACK with as the string. This notifies the server that it is a JACK client and needs its JACK port connections saved and restored. The server will now pay attention to any activity regarding the client (ie, port creation and destruction and port connection and disconnection.)

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#### 6.1.1.3 Another client

The user then starts a second client that uses the ALSA sequencer interface and wishes to save data on the server. It connects to the server with a different class to the JACK client and with the `LASH_Config_Data_Set` flag set.

The server sees that this client also didn't specify a project, and so adds it to the first available project; the same one as the previous project, ``project-1'`. It also sees that the client wants to store data on the server, and so it creates a directory within the project directory for this data to be stored in and creates a database-style object to manage the client's data.

If the user has the `lash_panel` client running, both clients will now be visible in the clients list for ``project-1'`.

The client then connects to the ALSA sequencer and sends its client ID to the server in the first character of the string of a `LASH_Alsa_Client_Name` event. The server regards this similarly to the other client's JACK client name.

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#### 6.1.1.4 Saving the project

After the user has done some work in the two clients, they want to save their work. They click the Save button in `lash_panel` (or use the `save` command in `lash_control`), and a `LASH_Save` event is sent to the server. The server recieves this and then iterates through each client in the project and checks its flags. The JACK client saves data by itself (it has the `LASH_Config_File` flag set,) so the server creates a directory under the project directory for it to save in and then sends a `LASH_Save_File` event to the client with a string containing the name of the directory it made. The client recieves the event and saves its data into the specified directory.

Next, the server examines the ALSA client. It wishes to save data on the server, so the server sends a `LASH_Save_Data_Set` to the client. With all of the clients iterated through, it now saves all the information it needs to be able to restore them; their working directory, command line options, etc. In order to do this, it asks the JACK server to find the connections for the JACK client, and asks the ALSA sequencer to find the connections for the ALSA client. It uses the client name and ID that both clients sent to the server after opening their connections to the respective systems. All of this information is stored in a file under the project's directory. When this is done, the server goes back to listening for events and configs.

The client, meanwhile, has recieved the `LASH_Save_Data_Set` event and sends back a number of configs to the server. When it has sent all the data it wishes to be saved, it sends back a `LASH_Save_Data_Set` event. The server passes all of the configs to the object managing the data store for the ALSA client. When the server recieves the `LASH_Save_Data_Set` event from the client, it tells the data store to write the data to disk. The save is now complete.

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#### 6.1.1.5 Client resumption

Unfortunately for the user, the ALSA client crashes. The server detects that the client has disconnected, and puts the client on a list of lost clients for the project. The user then starts another copy of the client, which connects to the server in the same way it did before. This time, however, the server checks through the list of lost clients and finds that the class of the new client matches the class of the lost client and so it resumes the lost client using the new one. It gives it the 128-bit ID of the lost client, adds it to the project, and then sends a `LASH_Restore_Data_Set` event to the client. The client then cleans itself up, ready to recieve the data set. The server sends the client the configs, and then another `LASH_Restore_Data_Set` event. The client recieves this data and its state has been restored that of the client that crashed.

The user can stop this behaviour by specifying the ``--lash-no-autoresume'` option on the client's command line.

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#### 6.1.1.6 Restoring the project

The user has to go off and do other things, and so they close down the clients and the server. Some time later, the user comes back and wants to start working again so first, as always, they start up the server. They then start the `lash_panel` program. Using the File->Open menu item, the user selects the directory (not file!) where they saved the project (by default ``~/audio-projects/project-1'`, but you can save to a more descriptive name). The lash_panel client sends a `LASH_Restore` event to the server with the specified directory as the string. The server opens the file that it saved before, and reads in all the information about the project and its clients. It creates a new project with this information. The clients are created as lost clients, however.

The server then iterates through each client and starts a new copy of it using the information provided when the original client connected. It also adds some command line options that are extracted by the client library. These specify the LASH ID of the client, the project name that it should be connecting to and the server's hostname and port. It then goes back to waiting.

The new JACK client then connects to the server as normal. When the server recieves it connection, it checks the client against the project's list of lost clients. This time, however, it has its ID specified, so the server will only resume a client with a matching ID. Lo and behold, such a client exists. The server resumes the old JACK client, telling it to load its state from the files in the project directory that the client previously stored. It does so with a `LASH_Restore_File` event with the string as the directory name. The ALSA client does exactly the same, except having its data restored through `LASH_Restore_Data_Set` as described above.

Only one thing remains for the clients to be fully restored: the JACK and ALSA sequencer connections. This happens when the clients send their `LASH_Jack_Client_Name` and `LASH_Alsa_Client_ID` events. The connections are stored with the LASH ID rather than the JACK client name or ALSA client ID. When the client registers its name or ID, the connections are converted from the LASH ID to the JACK client name or ALSA client ID, and the connections are restored. It also pays attention to connections to other clients within the same project, converting between JACK client names, ALSA client IDs and LASH IDs as appropriate.

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## 6.2 Types and functions

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### 6.2.1 Server interaction

Function: lash_client_t * lash_init (lash_args_t * args, const char * client_class, int client_flags, lash_protocol_t protocol)

  Open a connection to the server. Returns `NULL` on failure.

  The args argument must be obtained using `lash_extract_args`.

  The client_class argument must be a string that will never change over invocations of the program. If using GNU automake, the best way to do this is to use the `PACKAGE_NAME` macro that is automatically defined.

  The client_flags argument should be 0 or bitwise-OR'd values from this list:

  `LASH_Config_Data_Set`

    The client wishes to save its data use the LASH config system. See Configs and Event protocol.

  `LASH_Config_File`

    The client saves its data to a file. See section Event protocol.

  `LASH_Server_Interface`

    The client is a server interface. See section Server interfaces.

  `LASH_No_Autoresume`

    This flag is set by the `--lash-no-autoresume` command line option and should not normally be set by clients themselves.

  `LASH_Terminal`

    The client is dependant on being run in a terminal.

  `LASH_No_Start_Server`

    Do not attempt to start LASH server. This flag can be set by the `--lash-no-start-server` command line option.

  The protocol argument should be the version of the high-level protocol that the client implements See Protocol versioning for information on how to contruct a `lash_protocol_t` variable.

Function: lash_args_t * lash_extract_args (int * argc, char *** argv)

  Extract LASH-specific arguments from argc/argv for use in `lash_init`. This should be done before the client checks the arguments, obviously. Returned object must be cleaned up with lash_args_destroy.

Function: const char * lash_get_server_name (lash_client_t * client)

  Get the hostname of the server.

Function: unsigned int lash_get_pending_event_count (lash_client_t * client)

  Get the number of pending events.

Function: lash_event_t * lash_get_event (lash_client_t * client)

  Retrieve an event. The event must be freed using `lash_event_destroy`. Returns `NULL` if there are no events pending.

Function: unsigned int lash_get_pending_config_count (lash_client_t * client)

  Get the number of pending configs.

Function: lash_config_t * lash_get_config (lash_client_t * client)

  Retrieve a config. The config must be freed using `lash_config_destroy`. Returns `NULL` if there are no configs pending.

Function: void lash_send_event (lash_client_t * client, lash_event_t * event)

  Send an event to the server. The event must be created using `lash_event_new` or `lash_event_new_with_type`. The library takes over ownership of the memory and it should not be freed by the client.

Function: void lash_send_config (lash_client_t * client, lash_config_t * config)

  Send some configuration data to the server. The config must be created using `lash_config_new`, `lash_config_new_with_key` or `lash_config_dup`. The library takes over ownership of the memory (including the key, etc) and it should not be freed by the client.

Macro: lash_enabled (client)

  Check whether the lash_client_t pointer client is not `NULL`, and if it isn't, that the server is still connected.

Function: int lash_server_connected (lash_client_t * client)

  Check whether the server is connected. Returns 1 if the server is still connected or 0 if it isn't

Function: void lash_jack_client_name (lash_client_t * client, const char * name)

  Tell the server the client's JACK client name. This is a convenience function that just sends a LASH_Jack_Client_Name event to the server. See Normal LASH_Jack_Client_Name.

Function: void lash_alsa_client_id (lash_client_t * client, unsigned char id);

  Tell the server the client's ALSA client ID. This just is a convenience function that just sends a LASH_Alsa_Client_ID event to the server. See Normal LASH_Alsa_Client_ID.

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### 6.2.2 Protocol versioning

The event protocol (See section Event protocol,) is versioned with a major and minor component. The `lash_protocol_t` type represents a version number in a 32-bit unsigned integer split 16:16. A protocol is comptible with the server's protocol if the major numbers are the same and the minor number is less than, or equal to, the server's minor number (ie, 1.0 is compatible with a server using 1.0, 1.1 is compatible with a server using 1.3, but neither 2.0 or 1.6 are compatible with a server using 1.4. The minor component may be dropped in the future.

Macro: LASH_PROTOCOL (major, minor)

  Contruct a protocol version with a major component major and a minor component minor.

Macro: LASH_PROTOCOL_GET_MAJOR (protocol)

  Obtain the major component of a `lash_protocol_t` protocol version.

Macro: LASH_PROTOCOL_GET_MINOR (protocol)

  Obtain the minor component of a `lash_protocol_t` protocol version.

Function: const char * lash_protocol_string (lash_protocol_t protocol)

  Obtain a string representation of the protocol version protocol. String representations are of the form "major.minor".

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### 6.2.3 Events

Function: lash_event_t * lash_event_new (void)

Function: lash_event_t * lash_event_new_with_type (enum LASH_Event_Type type)

Function: void lash_event_destroy (lash_event_t * event)

Function: enum LASH_Event_Type lash_event_get_type (const lash_event_t * event)

Function: const char * lash_event_get_string (const lash_event_t * event)

Function: void lash_event_set_type (lash_event_t * event, enum LASH_Event_Type type)

Function: void lash_event_set_string (lash_event_t * event, const char * string);

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#### 6.2.3.1 Server interface events

All events have a LASH ID and project name property. They are only relevant to server interfaces, however, which need to refer to clients other than themselves and to projects (server interfaces are never assigned to a project.)

Function: void lash_event_get_client_id (const lash_event_t * event, uuid_t id)

  The event's client ID property will be copied into id.

Function: const char * lash_event_get_string (const lash_event_t * event)

Function: void lash_event_set_client_id (lash_event_t * event, enum uuid_t id)

Function: const char * lash_event_get_project (const lash_event_t * event)

Function: void lash_event_set_project (lash_event_t * event, const char * project_name);

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### 6.2.4 Configs

Function: lash_config_t * lash_config_new (void)

Function: lash_config_t * lash_config_dup (const lash_config_t * config)

Function: lash_config_t * lash_config_new_with_key (const char * key)

Function: void lash_config_destroy (lash_config_t * config)

Function: const char * lash_config_get_key (const lash_config_t * config)

Function: const void * lash_config_get_value (const lash_config_t * config)

Function: size_t lash_config_get_value_size (const lash_config_t * config)

Function: void lash_config_set_key (lash_config_t * config, const char * key)

Function: void lash_config_set_value (lash_config_t * config, const void * value, size_t value_size)

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#### 6.2.4.1 Semi-typed configs

With these functions, no type checking is done; you can do `lash_config_get_value_int` on a config that was set with `lash_config_set_value_float`. The integer values are converted to and from network byte order as appropriate.

Function: uint32_t lash_config_get_value_int (const lash_config_t * config)

Function: float lash_config_get_value_float (const lash_config_t * config)

Function: double lash_config_get_value_double (const lash_config_t * config)

Function: const char * lash_config_get_value_string (const lash_config_t * config)

Function: void lash_config_set_value_int (lash_config_t * config, uint32_t value)

Function: void lash_config_set_value_float (lash_config_t * config, float value)

Function: void lash_config_set_value_double (lash_config_t * config, double value)

Function: void lash_config_set_value_string (lash_config_t * config, const char * value)

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## 6.3 Event protocol

This section describes version 2.0 of the event protocol.

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### 6.3.1 Normal clients

This section deals with normal clients (as opposed to Server interfaces.)

`LASH_Client_Name`
  To server, non-`NULL` string

    Set the client's user-visible name.

  To server, `NULL` string

    Request the client's user-visible name.

  From server

    This will only be sent in response to a `LASH_Client_Name` with a `NULL` string. The string will be `NULL` if the client has not set a user-visible name, and the name itself if it has.

`LASH_Jack_Client_Name`

  To server, non-`NULL` string

    Tell the server what name the client is connected to JACK with. Clients should only ever send one non-`NULL` `LASH_Jack_Client_Name` event. Note that you must send this event after calling `jack_activate()`; otherwise, the server will not be able to connect the client's ports.

  To server, `NULL` string

    Request the client name that the server thinks the client is connected to JACK with.

  From server

    This will only be sent in response to a `LASH_Jack_Client_Name` with a `NULL` string. The string will be `NULL` if the client has not set a JACK client name, and the client name itself if it has.

`LASH_Alsa_Client_ID`

  To communicate ALSA client IDs within events, use the first character of a two character string of the form `{ id, '\0' }` as the event string. A convenience function, `lash_alsa_client_id`, exists to do this for you (see lash_alsa_client_id.)

  To server, non-`NULL` string

    Tell the server what ID the client is connected to ALSA with. Clients should only ever send one non-`NULL` `LASH_Alsa_Client_ID` event.

  To server, `NULL` string

    Request the client ID that the server thinks the client is connected to ALSA with.

  From server

    This will only be sent in response to a `LASH_Alsa_Client_ID` with a `NULL` string. The string will be `NULL` if the client has not set an ALSA client ID, and a string containing the ALSA client ID as described above if it has.

`LASH_Save_File`
  From server

    Tell the client to save all its data to files within a specific directory. The event string will never be `NULL` and will contain the name of the directory in which the client should save its data. Clients must always send a `LASH_Save_File` event back to the server when they have finished saving their data. The client should not rely on the directory existing after it has sent its `LASH_Save_File` event back. It is valid behaviour for a client to save no files within the directory. Files should always be overwritten (ie, using the "w" flag with `fopen()`,) preferably without user confirmation if you care for their sanity.

  From client

    Tell the server that the client has finished saving its data within the directory it was told to. The string is ignored.

`LASH_Restore_File`
  From server

    Tell the client to load all its data from files within a specific directory. The event string will never be `NULL` and will contain the name of the directory from which the client should load its data. Clients must always send a `LASH_Restore_File` event back to the server when they have finished restoring their data. The client should not rely on the directory existing after it has sent its `LASH_Restore_File` event back.

  From client

    Tell the server that the client has finished restoring its data from within the directory it was told to. The string is ignored.

`LASH_Save_Data_Set`
  From server

    Tell the client to send all its configuration data to the server with a number of configs. The client must always send a `LASH_Save_Data_Set` event back to the server when it has finished sending its configs. The event string will always be `NULL`.

  From client

    Tell the server that the client has finished sending its configs to the server. The event string is ignored.

`LASH_Restore_Data_Set`
  From server

    Tell the client to immediately expect a stream of configs from the server. This event will only be sent if there are one or more configs to be sent. The event string will always be `NULL`. The client must always send a `LASH_Restore_Data_Set` back to the server when it has recieved all of its configs.

  From client

    Tell the server that the client has finished recieving its configs from the server. The event string is ignored.

`LASH_Save`
  From client

    Tell the server to save the project that the client is attached to.

  From server

    Never occurs.

`LASH_Quit`
  From client

    Tell the server to close all clients in the project that the client is attached to.

  From server

    The client should immediately quit without saving. No more events will be sent by the server and the client's connection will be terminated.

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### 6.3.2 Server interfaces

Server interfaces are treated very differently to normal interfaces. Events from and to server interfaces are, for the most part, in order to describe and manipulate existing projects and clients. For this reason, the `lash_event_t` type has `project` and `client_id` properties which facilitate this. See Server interface events. The `project` property contains the name of the project.

A server interface should start up with the default assumption that there are no projects. Upon connection, the server will send appropriate events (`LASH_Project_Add`, `LASH_Client_Add`, `LASH_Client_Name`, etc) that describe the current state of the system. From then on, events will be sent to keep the interface up to date with the server's state.

`LASH_Project_Add`
  From interface

    Restore a project from an existing directory. The event string should contain the directory's name.

    `project`

      Ignored.

    `client_id`

      Ignored.

  From server

    A new project has been added. The event string will contain the project's name.

    `project`

      `NULL`

    `client_id`

      Undefined.

`LASH_Project_Remove`
  From interface

    Close an open project. All of the project's clients will be told to quit and the project will be removed from the server's project list.

    `project`

      The project to remove.

    `client_id`

      Ignored.

  From server

    A project has been removed.

    `project`

      The project that has been removed.

    `client_id`

      Undefined.

`LASH_Project_Dir`
  From interface, non-`NULL` string

    Move a project to a different directory. The directory name should be contained in the event's string.

    `project`

      The project to move.

    `client_id`

      Undefined.

  From interface, `NULL` string

    Request a project's directory.

    `project`

      The project whose directory is being requested.

    `client_id`

      Undefined.

  From server

    A declaration of the project's directory; either because it has been requested or because the project has been moved. The directory name is contained in the event's string.

    `project`

      The project whose directory is being declared.

    `client ID`

      Undefined.

`LASH_Project_Name`
  From interface

    Change a project's name. The new project name should be contained in the event's string.

    `project`

      The project name to change.

    `client_id`

      Undefined.

  From server

    A project's name has changed. The new project name is contained in the event's string.

    `project`

      The project name that has changed.

    `client ID`

      Undefined.

`LASH_Client_Add`
  From interface

    Should not occur

  From server

    A new client has been added.

    `project`

      The project that the new client has been added to.

    `client ID`

      The new client's ID.

`LASH_Client_Name`
  From interface, non-`NULL` string

    Should not occur.

  From interface, `NULL` string

    Request a client's name.

    `project`

      The client's project.

    `client ID`

      The client's ID.

  From server

    A declaration of a client's name; either because it has been requested or because the client set the name. The name is contained in the event's string.

    `project`

      The client's project.

    `client ID`

      The client's ID.

`LASH_Jack_Client_Name`
  From interface, non-`NULL` string

    Should not occur.

  From interface, `NULL` string

    Request a client's JACK client name.

    `project`

      The client's project.

    `client ID`

      The client's ID.

  From server

    A declaration of a client's JACK client name; either because it has been requested or because the client set the name. The client name is contained in the event's string.

    `project`

      The client's project.

    `client ID`

      The client's ID.

`LASH_Alsa_Client_ID`
  From interface, non-`NULL` string

    Should not occur.

  From interface, `NULL` string

    Request a client's ALSA client ID.

    `project`

      The client's project.

    `client ID`

      The client's LASH ID.

  From server

    A declaration of a client's ALSA client ID; either because it has been requested or because the client set the ID. The ALSA client ID is contained in the event's string, as desribed in Normal LASH_Alsa_Client_ID.

    `project`

      The client's project.

    `client ID`

      The client's LASH ID.

`LASH_Percentage`

  This event exists to provide user feedback on the status of save operations and perhaps other operations in future. The server will first send a percentage of 0, then successive percentages up to and including 100. When the operation is complete, the server will send a percentage of 0 again.

  From interface

    Should not occur.

  From server

    The percentage of completion of the current operation. The percentage is sent as a string, derived from `sprintf`ing an `int`.

    `project`

      The project whose operation is being described.

    `client ID`

      Undefined.

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# A. Copying restrictions

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## A.1 GNU Free Documentation License

Version 1.2, November 2002

    Copyright © 2000,2001,2002 Free Software Foundation, Inc.
    51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

    Everyone is permitted to copy and distribute verbatim copies
    of this license document, but changing it is not allowed.

1. PREAMBLE

   The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

   This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

   We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

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11. FUTURE REVISIONS OF THIS LICENSE

    The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/.

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### A.1.1 ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

      Copyright (C)  year  your name.
      Permission is granted to copy, distribute and/or modify this document
      under the terms of the GNU Free Documentation License, Version 1.2
      or any later version published by the Free Software Foundation;
      with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
      A copy of the license is included in the section entitled ``GNU
      Free Documentation License''.

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with...Texts." line with this:

        with the Invariant Sections being list their titles, with
        the Front-Cover Texts being list, and with the Back-Cover Texts
        being list.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.

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# Table of Contents

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# About This Document

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