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







transfer::receiver - Data source








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












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.













  

  
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.

  

  

  
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.

  

  

  
This method is like stream channel, except that the received data
      is written to the file path, replacing any prior content.










All objects created by the ::transfer::receiver command
    have the following general form:



  

  
The method method and its arg'uments determine the exact
      behavior of the command. See section Object methods for the
      detailed specifications.











  

  
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.

  

  
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.

  

  

  
This method returns a boolean value telling us whether a reception is in
      progress (True), or not (False).










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.



  

  
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.

  

  
This option specifies the mode the object is in. It is optional and
      defaults to active mode. The two possible modes are:







  

  
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.

  

  
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.







  

  
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.

  

  
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.

  

  
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.

  

  

  

  

  

  

  
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).

  

  
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.

  

  
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.

  

  
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.

  

  
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.












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 ...


    ...









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.








channel, copy, data destination, receiver, secure, ssl, tls,
    transfer








Transfer module








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








  

    0.2
    transfer