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 SF Trackers [
http://sourceforge.net/tracker/?group_id=12883].
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>