transfer::receiver(n)      Data transfer facilities      transfer::receiver(n)



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NAME
       transfer::receiver - Data source

SYNOPSIS
       package require Tcl  8.4

       package require snit  ?1.0?

       package require transfer::data::destination  ?0.2?

       package require transfer::connect  ?0.2?

       package require transfer::receiver  ?0.2?

       transfer::receiver object ?options...?

       transfer::receiver stream channel chan host port ?arg...?

       transfer::receiver stream file path host port ?arg...?

       objectName method ?arg arg ...?

       objectName destroy

       objectName start

       objectName busy

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DESCRIPTION
       This package pulls data destinations and connection setup together into
       a combined object for the reception of information coming in over a
       socket.  These objects understand all the options from objects created
       by the packages transfer::data::destination and transfer::connect.

API
   PACKAGE COMMANDS
       transfer::receiver object ?options...?
              This command creates a new receiver 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::receiver stream channel chan host port ?arg...?
              This method creates a fire-and-forget transfer for the data
              coming from the source at host/port (details below) and writing
              to 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 not closed when the transfer has
              completed. This is left to the completion callback.

              If both host and port are provided an active connection to the
              data source is made. If only a port is specified (with host the
              empty string) then a passive connection is made instead, i.e.
              the receiver then waits for a conneciton by the transmitter.

              Any arguments after the port are treated as options and are used
              to configure the internal receiver 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 receiver object.  This callback is only given
              the number of bytes and transfered, and possibly an error
              message. No reference to the internally used receiver 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
              receiver 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::receiver stream file path host port ?arg...?
              This method is like stream channel, except that the received
              data is written to the file path, replacing any prior content.

   OBJECT COMMAND
       All objects created by the ::transfer::receiver 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 reception is
              on progress will cause errors later on, when the reception
              completes and tries to access the now missing data structures of
              the destroyed object.

       objectName start
              This method initiates the data reception, setting up the
              connection first and then copying the received information into
              the destination.  The method will throw an error if a reception
              is already/still in progress.  I.e. it is not possible to run
              two receptions in parallel, only in sequence.  Errors will also
              be thrown if the configuration of the data destination 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
              reception is in progress (True), or not (False).

   OPTIONS
       All receiver objects support the union of the options supported by
       their connect and data destination components, plus one of their own.
       See also the documentation for the packages transfer::data::destination
       and transfer::connect.

       -command cmdprefix
              This option specifies the command to invoke when the reception
              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).

       -channel handle
              This option specifies that the destination of the data is a
              channel, and its associated argument is the handle of the
              channel to write the received data to.

       -file path
              This option specifies that the destination of the data is a
              file, and its associated argument is the path of the file to
              write the received data to.

       -variable varname
              This option specifies that the destination of the data is a
              variable, and its associated argument contains the name of the
              variable to write the received data to. The variable is assumed
              to be global or namespaced, anchored at the global namespace.

       -progress command
              This option, if specified, defines a command to be invoked for
              each chunk of bytes received, allowing the user to monitor the
              progress of the reception of the data. The callback is always
              invoked with one additional argument, the number of bytes
              received 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::receiver R -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 destination, receiver, secure, ssl, tls, transfer

CATEGORY
       Transfer module

COPYRIGHT
       Copyright (c) 2006 Andreas Kupries <andreas_kupries@users.sourceforge.net>




transfer                              0.2                transfer::receiver(n)
