NAME¶
transfer::transmitter - Data source
SYNOPSIS¶
package require
Tcl 8.4
package require
snit ?1.0?
package require
transfer::copy ?0.2?
package require
transfer::data::source ?0.2?
package require
transfer::connect ?0.2?
package require
transfer::transmitter ?0.2?
transfer::transmitter objectName ?
options...?
transfer::transmitter stream channel chan host
port ?
arg...?
transfer::transmitter stream file path host
port ?
arg...?
objectName method ?
arg arg ...?
objectName destroy
objectName start
objectName busy
DESCRIPTION¶
This package pulls data sources and connection setup together into a combined
object for the transmission of information over a socket. These objects
understand all the options from objects created by the packages
transfer::data::source and
transfer::connect.
API¶
PACKAGE COMMANDS¶
- transfer::transmitter objectName ?options...?
- This command creates a new transmitter object with an associated Tcl
command whose name is objectName. This object command is
explained in full detail in the sections Object command and
Object methods. The set of supported options is explained in
section Options.
The object command will be created under the current namespace if the
objectName is not fully qualified, and in the specified namespace
otherwise. The fully qualified name of the object command is returned as
the result of the command.
- transfer::transmitter stream channel chan host
port ?arg...?
- This method creates a fire-and-forget transfer for the data contained in
the channel chan, starting at the current seek location. The
channel is configured to use binary translation and encoding for the
transfer. The channel is automatically closed when the transfer has
completed.
If both host and port are provided an active connection
to the destination is made. If only a port is specified (with
host the empty string) then a passive connection is made
instead.
Any arguments after the port are treated as options and are used to
configure the internal transmitter object. See the section Options
for a list of the supported options and their meaning. Note however
that the signature of the command prefix specified for the -command
callback differs from the signature for the same option of the transmitter
object. This callback is only given the number of bytes and transfered,
and possibly an error message. No reference to the internally used
transmitter object is made.
The result returned by the command is the empty string if it was set to make
an active connection, and the port the internal transmitter object
is listening on otherwise, i.e when it is configured to connect
passively. See also the package transfer::connect and the
description of the method connect for where this behaviour comes
from.
- transfer::transmitter stream file path host
port ?arg...?
- This method is like stream channel, except that the data contained
in the file path is transfered.
OBJECT COMMAND¶
All objects created by the
::transfer::transmitter command have the
following general form:
- objectName method ?arg arg ...?
- The method method and its arg'uments determine the exact
behavior of the command. See section Object methods for the
detailed specifications.
OBJECT METHODS¶
- objectName destroy
- This method destroys the object. Doing so while a transmission is in
progress will cause errors later on, when the transmission completes and
tries to access the now missing data structures of the destroyed
object.
- objectName start
- This method initiates the data transmission, setting up the connection
first and then copying the information. The method will throw an error if
a transmission is already/still in progress. I.e. it is not possible to
run two transmissions in parallel on a single object, only in sequence.
Multiple transmitter objects are needed to manage parallel transfers, one
per transmission. Errors will also be thrown if the configuration of the
data source is invalid, or if no completion callback was specified.
The result returned by the method is the empty string for an object
configured to make an active connection, and the port the object is
listening on otherwise, i.e when it is configured to connect
passively. See also the package transfer::connect and the
description of the method connect for where this behaviour comes
from.
- objectName busy
- This method returns a boolean value telling us whether a transmission is
in progress ( True), or not (False).
OPTIONS¶
All transmitter objects support the union of the options supported by their
connect and data source components, plus two of their own. See also the
documentation for the packages
transfer::data::source and
transfer::connect.
- -blocksize int
- This option specifies the size of the chunks to be transmitted in one
block. Usage is optional, its default value is 1024.
- -command cmdprefix
- This option specifies the command to invoke when the transmission of the
information has been completed. The arguments given to this command are
the same as given to the completion callback of the command
transfer::copy::do provided by the package
transfer::copy.
- -mode mode
- This option specifies the mode the object is in. It is optional and
defaults to active mode. The two possible modes are:
- active
- In this mode the two options -host and -port are relevant
and specify the host and TCP port the object has to connect to. The host
is given by either name or IP address.
- passive
- In this mode the option -host has no relevance and is ignored
should it be configured. The only option the object needs is -port,
and it specifies the TCP port on which the listening socket is opened to
await the connection from the partner.
- -host hostname-or-ipaddr
- This option specifies the host to connect to in active mode, either
by name or ip-address. An object configured for passive mode
ignores this option.
- -port int
- For active mode this option specifies the port the object is
expected to connect to. For passive mode however it is the port
where the object creates the listening socket waiting for a connection. It
defaults to 0, which allows the OS to choose the actual port to
listen on.
- -socketcmd command
- This option allows the user to specify which command to use to open a
socket. The default is to use the builtin ::socket. Any compatible
with that command is allowed.
The envisioned main use is the specfication of tls::socket. I.e. this
option allows the creation of secure transfer channels, without making
this package explicitly dependent on the tls package.
See also section Secure connections.
- -encoding encodingname
- -eofchar eofspec
- -translation transspec
- These options are the same as are recognized by the builtin command
fconfigure. They provide the configuration to be set for the
channel between the two partners after it has been established, but before
the callback is invoked (See method connect).
- -string text
- This option specifies that the source of the data is an immediate string,
and its associated argument contains the string in question.
- -channel handle
- This option specifies that the source of the data is a channel, and its
associated argument is the handle of the channel containing the data.
- -file path
- This option specifies that the source of the data is a file, and its
associated argument is the path of the file containing the data.
- -variable varname
- This option specifies that the source of the data is a string stored in a
variable, and its associated argument contains the name of the variable in
question. The variable is assumed to be global or namespaced, anchored at
the global namespace.
- -size int
- This option specifies the size of the data transfer. It is optional and
defaults to -1. This value, and any other value less than zero signals to
transfer all the data from the source.
- -progress command
- This option, if specified, defines a command to be invoked for each chunk
of bytes transmitted, allowing the user to monitor the progress of the
transmission of the data. The callback is always invoked with one
additional argument, the number of bytes transmitted so far.
SECURE CONNECTIONS¶
One way to secure connections made by objects of this package is to require the
package
tls and then configure the option
-socketcmd to force
the use of command
tls::socket to open the socket.
# Load and initialize tls
package require tls
tls::init -cafile /path/to/ca/cert -keyfile ...
# Create a connector with secure socket setup,
transfer::transmitter T -socketcmd tls::socket ...
...
BUGS, IDEAS, FEEDBACK¶
This document, and the package it describes, will undoubtedly contain bugs and
other problems. Please report such in the category
transfer of the
Tcllib Trackers [
http://core.tcl.tk/tcllib/reportlist]. Please also
report any ideas for enhancements you may have for either package and/or
documentation.
KEYWORDS¶
channel, copy, data source, secure, ssl, tls, transfer, transmitter
CATEGORY¶
Transfer module
COPYRIGHT¶
Copyright (c) 2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>