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\input texinfo
@c %**start of header
@setfilename lash-manual.info
@settitle LASH Audio Session Handler
@c %**end of header
@ifinfo
This is the LASH Audio Session Handler Reference Manual,
Edition @PACKAGE_VERSION@, @DATE@ for LASH version @PACKAGE_VERSION@.
Copyright @copyright{} 2002, 2003 Robert Ham (rah@@bash.sh)
Copyright @copyright{} 2005, 2006 Dave Robillard (drobilla@@connect.carleton.ca)
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''.
@end ifinfo
@titlepage
@title LASH Reference Manual
@subtitle Audio application session management and configuration
@subtitle Edition @PACKAGE_VERSION@, @DATE@
@subtitle Covering LASH @PACKAGE_VERSION@
@author Bob Ham (rah@@bash.sh)
@author Dave Robillard (drobilla@@connect.carleton.ca)
@page
@vskip 0pt plus 1filll
Copyright @copyright{} 2002, 2003 Robert Ham (rah@@bash.sh)
Copyright @copyright{} 2005, 2006 Dave Robillard (drobilla@@connect.carleton.ca)
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''.
@end titlepage
@node Top, Introduction, ,(dir)
@comment node-name, next, previous, up
@ifinfo
This is the LASH Audio Session Handler
Reference Manual, edition @PACKAGE_VERSION@, @DATE@ for LASH version @PACKAGE_VERSION@.
@url{http://www.nongnu.org/lash}
@end ifinfo
@menu
* Introduction:: What LASH is all about
* Copying LASH:: How you can copy and distribute the LASH source code
* Installation:: How to get LASH onto your computer
* Server:: How to use the LASH server, @command{lashd}
* Server interface:: How to use the simple LASH server interface, @command{lash_control}
* Client reference:: How to program LASH clients using @code{liblash}
Appendicies
* GNU Free Documentation License:: How you can copy and distribute this document.
@end menu
@contents
@node Introduction, Copying LASH, Top, Top
@comment node-name, next, previous, up
@chapter 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, @command{lashd}, an application
library, @code{liblash}, and a control program - either the command-line
@command{lash_control} or the GTK @command{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.
@section Nomenclature
In order to describe the system, we should introduce some terminology.
First of all, the @dfn{server} is the @command{lashd} server program, an
omni-present marshaller and database for storing arbitrary application
data. The @dfn{library} is the @samp{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 @dfn{client}.
The server deals with things in terms of collections of clients,
called @dfn{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 @dfn{server interface} that allows the
user to control the server. There are two server interface included
with the system, the @command{lash_control} command-line interface,
and the @command{lash_panel} GTK interface.
@node Copying LASH, Installation, Introduction, Top
@comment node-name, next, previous, up
@chapter Copying LASH
LASH is distributed under the GNU General Public License. A copy of
the license text is provided in the file @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.
@node Installation, Server, Copying LASH, Top
@chapter Installation
This chapter describes how to get LASH installed on your system.
@section 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 @url{http://www.alsa-project.org/}.
JACK is available from @url{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
@url{http://e2fsprogs.sf.net/}. The libxml2 library is available from
@url{http://www.xmlsoft.org/}.
The LASH Control client depends on the GNU Readline library, available
from @url{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 @url{ftp://ftp.gtk.org/pub/gtk/v2.0/}.
The LASH Synth client has an optional GUI which also uses the GTK+
2 toolkit.
@section Installation
First off, you need to download the package. It is available from
the LASH webpage, @url{http://www.nongnu.org/lash}. After you have
downloaded it, unpack the tarball into a directory using @command{tar
-xzf /where/ever/you/put/lash-@PACKAGE_VERSION@.tar.gz} and change into
the source directory with @command{cd lash-@PACKAGE_VERSION@}.
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.
@subsection Configuration
To configure the package, there is a shell
script named @file{configure} in the top source directory. It is a
standard GNU autoconf configure script, and so accepts the standard GNU
configuration options (such as @option{--prefix}, @option{--datadir},
etc.) To run it type @command{./configure} and add any options.
The non-standard options that the script recognises are described below.
Running the script with the @option{--help} option will also provide a
quick summary of the recognised options.
@subsubsection Configure script options
@table @option
@item --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.
@item --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.
@item --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 @file{audio-projects}.
@end table
@subsection Building
To build the package, simply type @command{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.
@subsection Installing
To install the package, type @command{make install}
in the top source directory. By default the package installation
prefix is @file{/usr/local} but the @option{--prefix} option to the
configure script will change this. The @command{lashd} server and
the clients that were built are installed in @file{@var{prefix}/bin}.
The @code{liblash} client library is installed in @file{@var{prefix}/lib}.
The C header files for the client library are installed under
@file{@var{prefix}/include}. This manual is installed under
@file{@var{prefix}/info}.
With @command{make install}, the package is installed with debugging
symbols in the object files. To save space, you can install with
@command{make install-strip} to install the object files without
debugging symbols.
@node Server, Server interface, Installation, Top
@comment node-name, next, previous, up
@chapter Server
The LASH server is called @file{lashd}.
@node Server interface, Client reference, Server, Top
@chapter Server interface
For a command line interface, run the command @command{lashd_control}.
There is a @command{help} command.
For a graphical interface, run the command @command{lash_panel}.
It should be relatively self-explanatory.
@node Client reference, Operational overview, Server interface, Top
@chapter Client reference
This chapter provides a programming guide and library reference for
programmers of LASH clients.
@menu
* Operational overview:: An overview of how servers and clients operate
* Types and functions:: A detailed description of types and function that LASH clients can use
* Event protocol:: A detailed description of the protocol used for client/server communication
@end menu
@node Operational overview, Types and functions, Client reference, Client reference
@section 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 @command{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 @dfn{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 @code{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 @code{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
@dfn{config}s 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 @code{uint32_t} integer due to byte-order conversions
done when sending data over the network.)
@subsection 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.
@subsubsection 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
@command{lash_panel} program (though this is not necessary, and it can
be started later at any time).
Unless the environment variable @code{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
@command{--lash-no-start-server} option on the client's command line.
If you're using a Bourne compatible shell like @code{bash} (if you don't
know, you probably are) you can disable auto-start with the following
command:
@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.
@subsubsection 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 @emph{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 @code{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 @dfn{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 @samp{project-1} in the directory
@file{/home/@var{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 @command{lash_panel} client running, the new project
will appear as a tab with the title @samp{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 @code{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.)
@subsubsection 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
@code{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, @samp{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 @command{lash_panel} client running, both clients
will now be visible in the clients list for @samp{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
@code{LASH_Alsa_Client_Name} event. The server regards this similarly
to the other client's JACK client name.
@subsubsection 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 @command{lash_panel}
(or use the @command{save} command in @command{lash_control}), and a
@code{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 @code{LASH_Config_File}
flag set,) so the server creates a directory under the project directory
for it to save in and then sends a @code{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 @code{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 @code{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 @code{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
@code{LASH_Save_Data_Set} event from the client, it tells the data store
to write the data to disk. The save is now complete.
@subsubsection 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 @code{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 @code{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
@option{--lash-no-autoresume} option on the client's command line.
@subsubsection 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 @command{lash_panel} program. Using the File->Open
menu item, the user selects the directory (not file!) where they saved
the project (by default @file{~/audio-projects/project-1}, but you
can save to a more descriptive name). The lash_panel client sends a
@code{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 @code{LASH_Restore_File} event with
the string as the directory name. The ALSA client does exactly the same,
except having its data restored through @code{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
@code{LASH_Jack_Client_Name} and @code{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.
@node Types and functions, Event protocol, Operational overview, Client reference
@section Types and functions
@subsection Server interaction
@deftypefun {lash_client_t *} lash_init (lash_args_t * @var{args}, const char * @var{client_class}, int @var{client_flags}, lash_protocol_t @var{protocol})
Open a connection to the server. Returns @code{NULL} on failure.
The @var{args} argument must be obtained using @code{lash_extract_args}.
The @var{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 @code{PACKAGE_NAME} macro that is automatically defined.
The @var{client_flags}
argument should be 0 or bitwise-OR'd values from this list:
@table @code
@item LASH_Config_Data_Set
The client wishes to save its data use the LASH config system. See @ref{Configs} and
@ref{Event protocol}.
@item LASH_Config_File
The client saves its data to a file. @xref{Event protocol}.
@item LASH_Server_Interface
The client is a server interface. @xref{Server interfaces}.
@item LASH_No_Autoresume
This flag is set by the @command{--lash-no-autoresume} command line option and
should not normally be set by clients themselves.
@item LASH_Terminal
The client is dependant on being run in a terminal.
@item LASH_No_Start_Server
Do not attempt to start LASH server.
This flag can be set by the @command{--lash-no-start-server} command line option.
@end table
The @var{protocol} argument should be the version of the high-level protocol that the client
implements See @ref{Protocol versioning} for information on how to contruct a @code{lash_protocol_t}
variable.
@end deftypefun
@deftypefun {lash_args_t *} lash_extract_args (int * @var{argc}, char *** @var{argv})
Extract LASH-specific arguments from argc/argv for use in @code{lash_init}. This should be done before the
client checks the arguments, obviously. Returned object must be cleaned up with lash_args_destroy.
@end deftypefun
@deftypefun {const char *} lash_get_server_name (lash_client_t * @var{client})
Get the hostname of the server.
@end deftypefun
@deftypefun {unsigned int} lash_get_pending_event_count (lash_client_t * @var{client})
Get the number of pending events.
@end deftypefun
@deftypefun {lash_event_t *} lash_get_event (lash_client_t * @var{client})
Retrieve an event. The event must be freed using @code{lash_event_destroy}.
Returns @code{NULL} if there are no events pending.
@end deftypefun
@deftypefun {unsigned int} lash_get_pending_config_count (lash_client_t * @var{client})
Get the number of pending configs.
@end deftypefun
@deftypefun {lash_config_t *} lash_get_config (lash_client_t * @var{client})
Retrieve a config. The config must be freed using @code{lash_config_destroy}.
Returns @code{NULL} if there are no configs pending.
@end deftypefun
@deftypefun void lash_send_event (lash_client_t * @var{client}, lash_event_t * @var{event})
Send an event to the server. The event must be created using
@code{lash_event_new} or @code{lash_event_new_with_type}. The library takes over
ownership of the memory and it should not be freed by the client.
@end deftypefun
@deftypefun void lash_send_config (lash_client_t * @var{client}, lash_config_t * @var{config})
Send some configuration data to the server. The config must be created using
@code{lash_config_new}, @code{lash_config_new_with_key} or
@code{lash_config_dup}. The library takes
over ownership of the memory (including the key, etc) and it should not be freed by the client.
@end deftypefun
@defmac lash_enabled (client)
Check whether the lash_client_t pointer @var{client} is not @code{NULL}, and if it
isn't, that the server is still connected.
@end defmac
@deftypefun int lash_server_connected (lash_client_t * @var{client})
Check whether the server is connected. Returns 1 if the server is still
connected or 0 if it isn't
@end deftypefun
@deftypefun void lash_jack_client_name (lash_client_t * @var{client}, const char * @var{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. @xref{Normal LASH_Jack_Client_Name}.
@end deftypefun
@anchor{lash_alsa_client_id}
@deftypefun void lash_alsa_client_id (lash_client_t * @var{client}, unsigned char @var{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. @xref{Normal LASH_Alsa_Client_ID}.
@end deftypefun
@subsection Protocol versioning
@anchor{Protocol versioning}
The event protocol (@xref{Event protocol},) is versioned with a major and minor component.
The @code{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.
@defmac LASH_PROTOCOL (major, minor)
Contruct a protocol version with a major component @var{major} and a minor
component @var{minor}.
@end defmac
@defmac LASH_PROTOCOL_GET_MAJOR (protocol)
Obtain the major component of a @code{lash_protocol_t} protocol version.
@end defmac
@defmac LASH_PROTOCOL_GET_MINOR (protocol)
Obtain the minor component of a @code{lash_protocol_t} protocol version.
@end defmac
@deftypefun const char * lash_protocol_string (lash_protocol_t @var{protocol})
Obtain a string representation of the protocol version @var{protocol}.
String representations are of the form ``@var{major}.@var{minor}''.
@end deftypefun
@subsection Events
@anchor{Events}
@deftypefun {lash_event_t *} lash_event_new (@var{void})
@end deftypefun
@deftypefun {lash_event_t *} lash_event_new_with_type (enum LASH_Event_Type @var{type})
@end deftypefun
@deftypefun void lash_event_destroy (lash_event_t * @var{event})
@end deftypefun
@deftypefun {enum LASH_Event_Type} lash_event_get_type (const lash_event_t * @var{event})
@end deftypefun
@deftypefun {const char *} lash_event_get_string (const lash_event_t * @var{event})
@end deftypefun
@deftypefun void lash_event_set_type (lash_event_t * @var{event}, enum LASH_Event_Type @var{type})
@end deftypefun
@deftypefun void lash_event_set_string (lash_event_t * @var{event}, const char * @var{string});
@end deftypefun
@subsubsection Server interface events
@anchor{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.)
@deftypefun {void} lash_event_get_client_id (const lash_event_t * @var{event}, uuid_t @var{id})
The event's client ID property will be copied into @var{id}.
@end deftypefun
@deftypefun {const char *} lash_event_get_string (const lash_event_t * @var{event})
@end deftypefun
@deftypefun void lash_event_set_client_id (lash_event_t * @var{event}, enum uuid_t @var{id})
@end deftypefun
@deftypefun {const char *} lash_event_get_project (const lash_event_t * @var{event})
@end deftypefun
@deftypefun void lash_event_set_project (lash_event_t * @var{event}, const char * @var{project_name});
@end deftypefun
@subsection Configs
@anchor{Configs}
@deftypefun {lash_config_t *} lash_config_new (@var{void})
@end deftypefun
@deftypefun {lash_config_t *} lash_config_dup (const lash_config_t * @var{config})
@end deftypefun
@deftypefun {lash_config_t *} lash_config_new_with_key (const char * @var{key})
@end deftypefun
@deftypefun void lash_config_destroy (lash_config_t * @var{config})
@end deftypefun
@deftypefun {const char *} lash_config_get_key (const lash_config_t * @var{config})
@end deftypefun
@deftypefun {const void *} lash_config_get_value (const lash_config_t * @var{config})
@end deftypefun
@deftypefun size_t lash_config_get_value_size (const lash_config_t * @var{config})
@end deftypefun
@deftypefun void lash_config_set_key (lash_config_t * @var{config}, const char * @var{key})
@end deftypefun
@deftypefun void lash_config_set_value (lash_config_t * @var{config}, const void * @var{value}, size_t @var{value_size})
@end deftypefun
@subsubsection Semi-typed configs
With these functions, no type checking is done; you can do
@code{lash_config_get_value_int} on a config that was set with
@code{lash_config_set_value_float}. The integer values are converted
to and from network byte order as appropriate.
@deftypefun uint32_t lash_config_get_value_int (const lash_config_t * @var{config})
@end deftypefun
@deftypefun float lash_config_get_value_float (const lash_config_t * @var{config})
@end deftypefun
@deftypefun double lash_config_get_value_double (const lash_config_t * @var{config})
@end deftypefun
@deftypefun {const char *} lash_config_get_value_string (const lash_config_t * @var{config})
@end deftypefun
@deftypefun void lash_config_set_value_int (lash_config_t * @var{config}, uint32_t @var{value})
@end deftypefun
@deftypefun void lash_config_set_value_float (lash_config_t * @var{config}, float @var{value})
@end deftypefun
@deftypefun void lash_config_set_value_double (lash_config_t * @var{config}, double @var{value})
@end deftypefun
@deftypefun void lash_config_set_value_string (lash_config_t * @var{config}, const char * @var{value})
@end deftypefun
@node Event protocol, Normal clients, Types and functions, Client reference
@section Event protocol
This section describes version 2.0 of the event protocol.
@menu
* Normal clients:: The protocol for normal LASH clients
* Server interfaces:: The protocol for server interfaces
@end menu
@node Normal clients, Server interfaces, Event protocol, Event protocol
@subsection Normal clients
This section deals with normal clients (as opposed to @ref{Server interfaces}.)
@table @code
@item LASH_Client_Name
@table @emph
@item To server, non-@code{NULL} string
Set the client's user-visible name.
@item To server, @code{NULL} string
Request the client's user-visible name.
@item From server
This will only be sent in response to a @code{LASH_Client_Name} with a
@code{NULL} string. The string will be @code{NULL} if the client has not
set a user-visible name, and the name itself if it has.
@end table
@item LASH_Jack_Client_Name
@anchor{Normal LASH_Jack_Client_Name}
@table @emph
@item To server, non-@code{NULL} string
Tell the server what name the client is connected to JACK with.
Clients should only ever send one non-@code{NULL} @code{LASH_Jack_Client_Name}
event. Note that you @emph{must} send this event @emph{after} calling
@code{jack_activate()}; otherwise, the server will not be able to connect
the client's ports.
@item To server, @code{NULL} string
Request the client name that the server thinks the client is connected to
JACK with.
@item From server
This will only be sent in response to a @code{LASH_Jack_Client_Name} with a
@code{NULL} string. The string will be @code{NULL} if the client has not
set a JACK client name, and the client name itself if it has.
@end table
@item LASH_Alsa_Client_ID
@anchor{Normal LASH_Alsa_Client_ID}
To communicate ALSA client IDs within events, use the first character
of a two character string of the form @code{@{ @var{id}, '\0' @}} as the
event string. A
convenience function, @code{lash_alsa_client_id}, exists to do this for you
(see @ref{lash_alsa_client_id}.)
@table @emph
@item To server, non-@code{NULL} string
Tell the server what ID the client is connected to ALSA with.
Clients should only ever send one non-@code{NULL} @code{LASH_Alsa_Client_ID}
event.
@item To server, @code{NULL} string
Request the client ID that the server thinks the client is connected to
ALSA with.
@item From server
This will only be sent in response to a @code{LASH_Alsa_Client_ID} with a
@code{NULL} string. The string will be @code{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.
@end table
@item LASH_Save_File
@table @emph
@item From server
Tell the client to save all its data to files within a specific directory.
The event string will never be @code{NULL} and will contain the name of the
directory in which the client should save its data. Clients must always
send a @code{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 @code{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 @code{fopen()},) preferably without user confirmation if you care
for their sanity.
@item From client
Tell the server that the client has finished saving its data within the
directory it was told to. The string is ignored.
@end table
@item LASH_Restore_File
@table @emph
@item From server
Tell the client to load all its data from files within a specific directory.
The event string will never be @code{NULL} and will contain the name of the
directory from which the client should load its data. Clients must always
send a @code{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 @code{LASH_Restore_File}
event back.
@item 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.
@end table
@item LASH_Save_Data_Set
@table @emph
@item 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 @code{LASH_Save_Data_Set}
event back to the server when it has finished sending its configs. The
event string will always be @code{NULL}.
@item From client
Tell the server that the client has finished sending its configs to the
server. The event string is ignored.
@end table
@item LASH_Restore_Data_Set
@table @emph
@item 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 @code{NULL}. The client must always send
a @code{LASH_Restore_Data_Set} back to the server when it has recieved
all of its configs.
@item From client
Tell the server that the client has finished recieving its configs from the
server. The event string is ignored.
@end table
@item LASH_Save
@table @emph
@item From client
Tell the server to save the project that the client is attached to.
@item From server
Never occurs.
@end table
@item LASH_Quit
@table @emph
@item From client
Tell the server to close all clients in the project that the client is attached to.
@item 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.
@end table
@end table
@node Server interfaces, GNU Free Documentation License, Normal clients, Event protocol
@subsection 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 @code{lash_event_t} type has
@code{project} and @code{client_id} properties which facilitate this. @xref{Server interface
events}. The @code{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 (@code{LASH_Project_Add},
@code{LASH_Client_Add}, @code{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.
@table @code
@c ***
@c *** LASH_Project_Add
@c ***
@item LASH_Project_Add
@table @emph
@item From interface
Restore a project from an existing directory. The event string should contain the
directory's name.
@table @code
@item project
Ignored.
@item client_id
Ignored.
@end table
@item From server
A new project has been added. The event string will contain the project's name.
@table @code
@item project
@code{NULL}
@item client_id
Undefined.
@end table
@end table
@c ***
@c *** LASH_Project_Remove
@c ***
@item LASH_Project_Remove
@table @emph
@item 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.
@table @code
@item project
The project to remove.
@item client_id
Ignored.
@end table
@item From server
A project has been removed.
@table @code
@item project
The project that has been removed.
@item client_id
Undefined.
@end table
@end table
@c ***
@c *** LASH_Project_Dir
@c ***
@item LASH_Project_Dir
@table @emph
@item From interface, non-@code{NULL} string
Move a project to a different directory. The directory name should be contained in
the event's string.
@table @code
@item project
The project to move.
@item client_id
Undefined.
@end table
@item From interface, @code{NULL} string
Request a project's directory.
@table @code
@item project
The project whose directory is being requested.
@item client_id
Undefined.
@end table
@item 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.
@table @code
@item project
The project whose directory is being declared.
@item client ID
Undefined.
@end table
@end table
@c ***
@c *** LASH_Project_Name
@c ***
@item LASH_Project_Name
@table @emph
@item From interface
Change a project's name. The new project name should be contained in the
event's string.
@table @code
@item project
The project name to change.
@item client_id
Undefined.
@end table
@item From server
A project's name has changed. The new project name is contained in the event's
string.
@table @code
@item project
The project name that has changed.
@item client ID
Undefined.
@end table
@end table
@c ***
@c *** LASH_Client_Add
@c ***
@item LASH_Client_Add
@table @emph
@item From interface
Should not occur
@item From server
A new client has been added.
@table @code
@item project
The project that the new client has been added to.
@item client ID
The new client's ID.
@end table
@end table
@c ***
@c *** LASH_Client_Name
@c ***
@item LASH_Client_Name
@table @emph
@item From interface, non-@code{NULL} string
Should not occur.
@item From interface, @code{NULL} string
Request a client's name.
@table @code
@item project
The client's project.
@item client ID
The client's ID.
@end table
@item 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.
@table @code
@item project
The client's project.
@item client ID
The client's ID.
@end table
@end table
@c ***
@c *** LASH_Jack_Client_Name
@c ***
@item LASH_Jack_Client_Name
@table @emph
@item From interface, non-@code{NULL} string
Should not occur.
@item From interface, @code{NULL} string
Request a client's JACK client name.
@table @code
@item project
The client's project.
@item client ID
The client's ID.
@end table
@item 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.
@table @code
@item project
The client's project.
@item client ID
The client's ID.
@end table
@end table
@c ***
@c *** LASH_Alsa_Client_ID
@c ***
@item LASH_Alsa_Client_ID
@table @emph
@item From interface, non-@code{NULL} string
Should not occur.
@item From interface, @code{NULL} string
Request a client's ALSA client ID.
@table @code
@item project
The client's project.
@item client ID
The client's LASH ID.
@end table
@item 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 @ref{Normal LASH_Alsa_Client_ID}.
@table @code
@item project
The client's project.
@item client ID
The client's LASH ID.
@end table
@end table
@c ***
@c *** LASH_Percentage
@c ***
@item 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.
@table @emph
@item From interface
Should not occur.
@item From server
The percentage of completion of the current operation. The percentage
is sent as a string, derived from @code{sprintf}ing an @code{int}.
@table @code
@item project
The project whose operation is being described.
@item client ID
Undefined.
@end table
@end table
@end table
@node GNU Free Documentation License, , Server interfaces, Top
@appendix Copying restrictions
@include fdl.texi
@bye
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