This function manage to persistently store sensible parameters for configuring communication between the server and the client, as well as, any other persistent data you may need. Parameters remain set even if the client disconnects and then reconnects to R, as long R was not restarted.
parSocket(client, serverport = 8888, clientsocket = client, ...)the client identification. By default, it is the socket
identifier as it appears in [getSocketClients(). Since no attempt is made
to check if the client really exists and is connected, you can create fake
ones, outside of the socket server, to test your code for instance.
the port on which the server is running, 8888 by default. Not important for fake socket client configurations.
the Tcl name of the socket where the client is connected.
By default, it is the same as client name, but in case it was modified, do
provide a correct clientsocket string if you want to be able to activate a
redirection to it (see socketClientConnection()).
the parameters you want to change as named arguments. Non named
arguments are ignored with a warning. If you specify arg = NULL, the
corresponding variable is deleted from the environment.
Returns the environment where parameters and data for the client are stored. To access those data, see examples below.
You can assign the environment to a variable, and then, access its content
like if it was a list (e$var or e$var <- "new value"). To get a list of
the content, use ls(parSocket(client, port)), or
ls(parSocket(client, port), all.names = TRUE), but not
names(parSocket(client, port)). As long as you keep a variable pointing on
that environment alive, you have access to last values (i.e., changes done
elsewhere are taken into account). If you want a frozen snapshot of the
parameters, you should use myvar <- as.list(parSocket(client, port).
There is a convenient placeholder for code send by the client to insert
automatically the right socket and serverport in parSocket(): <<<s>>>.
Hence, code that the client send to access or change its environment is just
parSocket(<<<s>>>, bare = FALSE) or parSocket(<<<s>>>)$bare to set or get
one parameter. Note that you can set or change many parameters at once.
Currently, parameters are:
bare = TRUE|FALSE for "bare" mode (no prompt, no echo, no multiline; by default, bare = TRUE),
multiline = TRUE|FALSE: does the server accept code spread on multiple
lines and send in several steps (by default, yes, but works only if
bare = FALSE.
echo = TRUE|FALSE is the command echoed to the regular R console (by
default echo = FALSE).
last = "" string to append to each output (for instance to indicate that processing is done),
prompt = "> ", the prompt to use (if not in bare mode) and
continue = "+ " the continuation prompt to use, when multiline mode is
active. You can only cancel a multiline mode by completing the R code you are
sending to the server, but you can break it too by sending <<<esc>>> before
the next instruction. You can indicate <<<q>>> or <<<Q>>> at the very
beginning of an instruction to tell R to disconnect the connection after the
command is processed and result is returned (with <<<q>>>), or when the
instructions are received but before they are processed (with <<<Q>>>).
This is useful for "one shot" clients (clients that connect, send code and
want to disconnect immediately after that). The code send by the server to
the client to tell him to disconnect gracefully (and do some housekeeping) is
\\f send at the beginning of one line. So, clients should detect this and
perform the necessary actions to gracefully disconnect from the server as
soon as possible, and he cannot send further instructions from this moment
on.
For clients that repeatedly connect and disconnect, but want persistent data,
the default client identifier (the socket name) cannot be used, because that
socket name would change from connection to connection. The client must then
provide its own identifier. This is done by sending <<<id=myID>>> at the
very beginning of a command. This must be done for all commands! myID must
use only characters or digits. This code could be followed by <<<e>>>,
<<<h>>> or <<<H>>>. These commands are intended for R editors/IDE. The
first code <<<e>>> sets the server into a mode that is suitable to
evaluate R code (including in a multi-line way). The other code temporarily
configure the server to run the command (in single line mode only) in a
hidden way. They can be used to execute R code without displaying it in the
console (for instance, to start context help, to get a calltip, or a
completion list, etc.). The differences between <<<h>>> and <<<H>>> is
that the former waits for command completion and returns results of the
command to the client before disconnecting, while the latter disconnects from
the client before executing the command.
There is a simple client (written in Tcl) available in the /etc subdirectory of this package installation. Please, read the 'ReadMe.txt' file in the same directory to learn how to use it. You can use this simple client to experiment with the communication using these sockets, but it does not provide advanced command line edition, no command history, and avoid pasting more than one line of code into it.
startSocketServer(), sendSocketClients(), getSocketClients(),
socketClientConnection()
# NOT RUN {
# We use a fake socket client configuration environment
e <- parSocket("fake")
# Look at what it contains
ls(e)
# Get one data
e$bare
# ... or
parSocket("fake")$bare
# Change it
parSocket("fake", bare = FALSE)$bare
# Note it is changed too for e
e$bare
# You can change it too with
e$bare <- TRUE
e$bare
parSocket("fake")$bare
# Create a new entry
e$foo <- "test"
ls(e)
parSocket("fake")$foo
# Now delete it
parSocket("fake", foo = NULL)
ls(e)
# Our fake socket config is in SciViews:TempEnv environment
s <- search()
l <- length(s)
pos <- (1:l)[s == "SciViews:TempEnv"]
ls(pos = pos) # It is named 'SocketClient_fake'
# Delete it
rm(SocketClient_fake, pos = pos)
# Do some house keeping
rm(list = c("s", "l", "pos"))
# }
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