elisp: Network Processes
36.17.1 ‘make-network-process’
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The basic function for creating network connections and network servers
is ‘make-network-process’. It can do either of those jobs, depending on
the arguments you give it.
-- Function: make-network-process &rest args
This function creates a network connection or server and returns
the process object that represents it. The arguments ARGS are a
list of keyword/argument pairs. Omitting a keyword is always
equivalent to specifying it with value ‘nil’, except for ‘:coding’,
‘:filter-multibyte’, and ‘:reuseaddr’. Here are the meaningful
keywords (those corresponding to network options are listed in the
following section):
:name NAME
Use the string NAME as the process name. It is modified if
necessary to make it unique.
:type TYPE
Specify the communication type. A value of ‘nil’ specifies a
stream connection (the default); ‘datagram’ specifies a
datagram connection; ‘seqpacket’ specifies a sequenced packet
stream connection. Both connections and servers can be of
these types.
:server SERVER-FLAG
If SERVER-FLAG is non-‘nil’, create a server. Otherwise,
create a connection. For a stream type server, SERVER-FLAG
may be an integer, which then specifies the length of the
queue of pending connections to the server. The default queue
length is 5.
:host HOST
Specify the host to connect to. HOST should be a host name or
Internet address, as a string, or the symbol ‘local’ to
specify the local host. If you specify HOST for a server, it
must specify a valid address for the local host, and only
clients connecting to that address will be accepted.
:service SERVICE
SERVICE specifies a port number to connect to; or, for a
server, the port number to listen on. It should be a service
name that translates to a port number, or an integer
specifying the port number directly. For a server, it can
also be ‘t’, which means to let the system select an unused
port number.
:family FAMILY
FAMILY specifies the address (and protocol) family for
communication. ‘nil’ means determine the proper address
family automatically for the given HOST and SERVICE. ‘local’
specifies a Unix socket, in which case HOST is ignored.
‘ipv4’ and ‘ipv6’ specify to use IPv4 and IPv6, respectively.
:local LOCAL-ADDRESS
For a server process, LOCAL-ADDRESS is the address to listen
on. It overrides FAMILY, HOST and SERVICE, so you might as
well not specify them.
:remote REMOTE-ADDRESS
For a connection, REMOTE-ADDRESS is the address to connect to.
It overrides FAMILY, HOST and SERVICE, so you might as well
not specify them.
For a datagram server, REMOTE-ADDRESS specifies the initial
setting of the remote datagram address.
The format of LOCAL-ADDRESS or REMOTE-ADDRESS depends on the
address family:
- An IPv4 address is represented as a five-element vector
of four 8-bit integers and one 16-bit integer ‘[A B C D
P]’ corresponding to numeric IPv4 address A.B.C.D and
port number P.
- An IPv6 address is represented as a nine-element vector
of 16-bit integers ‘[A B C D E F G H P]’ corresponding to
numeric IPv6 address A:B:C:D:E:F:G:H and port number P.
- A local address is represented as a string, which
specifies the address in the local address space.
- An unsupported-family address is represented by a cons
‘(F . AV)’, where F is the family number and AV is a
vector specifying the socket address using one element
per address data byte. Do not rely on this format in
portable code, as it may depend on implementation defined
constants, data sizes, and data structure alignment.
:nowait BOOL
If BOOL is non-‘nil’ for a stream connection, return without
waiting for the connection to complete. When the connection
succeeds or fails, Emacs will call the sentinel function, with
a second argument matching ‘"open"’ (if successful) or
‘"failed"’. The default is to block, so that
‘make-network-process’ does not return until the connection
has succeeded or failed.
:stop STOPPED
If STOPPED is non-‘nil’, start the network connection or
server in the stopped state.
:buffer BUFFER
Use BUFFER as the process buffer.
:coding CODING
Use CODING as the coding system for this process. To specify
different coding systems for decoding data from the connection
and for encoding data sent to it, specify ‘(DECODING .
ENCODING)’ for CODING.
If you don’t specify this keyword at all, the default is to
determine the coding systems from the data.
:noquery QUERY-FLAG
Initialize the process query flag to QUERY-FLAG. 
Query
Before Exit.
:filter FILTER
Initialize the process filter to FILTER.
:filter-multibyte MULTIBYTE
If MULTIBYTE is non-‘nil’, strings given to the process filter
are multibyte, otherwise they are unibyte. The default is the
default value of ‘enable-multibyte-characters’.
:sentinel SENTINEL
Initialize the process sentinel to SENTINEL.
:log LOG
Initialize the log function of a server process to LOG. The
log function is called each time the server accepts a network
connection from a client. The arguments passed to the log
function are SERVER, CONNECTION, and MESSAGE; where SERVER is
the server process, CONNECTION is the new process for the
connection, and MESSAGE is a string describing what has
happened.
:plist PLIST
Initialize the process plist to PLIST.
The original argument list, modified with the actual connection
information, is available via the ‘process-contact’ function.
Info Catalog
elisp: Low-Level Network
elisp: Network Options