1transfer::transmitter(n) Data transfer facilities transfer::transmitter(n)
2______________________________________________________________________________
6
8 transfer::transmitter - Data source
9
11 package require Tcl 8.4
12 package require snit ?1.0?
14 package require transfer::copy ?0.2?
16 package require transfer::data::source ?0.2?
18 package require transfer::connect ?0.2?
20 package require transfer::transmitter ?0.2?
22 transfer::transmitter objectName ?options...?
24 transfer::transmitter stream channel chan host port ?arg...?
26 transfer::transmitter stream file path host port ?arg...?
28 objectName method ?arg arg ...?
30 objectName destroy
32 objectName start
34 objectName busy
36______________________________________________________________________________
38
40 This package pulls data sources and connection setup together into a
41 combined object for the transmission of information over a socket.
42 These objects understand all the options from objects created by the
43 packages transfer::data::source and transfer::connect.
44
46 PACKAGE COMMANDS
47 transfer::transmitter objectName ?options...?
48 This command creates a new transmitter object with an associated
49 Tcl command whose name is objectName. This object command is
50 explained in full detail in the sections Object command and Ob‐
51 ject methods. The set of supported options is explained in sec‐
52 tion Options.
53 The object command will be created under the current namespace
55 if the objectName is not fully qualified, and in the specified
56 namespace otherwise. The fully qualified name of the object
57 command is returned as the result of the command.
58 transfer::transmitter stream channel chan host port ?arg...?
60 This method creates a fire-and-forget transfer for the data con‐
61 tained in the channel chan, starting at the current seek loca‐
62 tion. The channel is configured to use binary translation and
63 encoding for the transfer. The channel is automatically closed
64 when the transfer has completed.
65 If both host and port are provided an active connection to the
67 destination is made. If only a port is specified (with host the
68 empty string) then a passive connection is made instead.
69 Any arguments after the port are treated as options and are used
71 to configure the internal transmitter object. See the section
72 Options for a list of the supported options and their meaning.
73 Note however that the signature of the command prefix specified
74 for the -command callback differs from the signature for the
75 same option of the transmitter object. This callback is only
76 given the number of bytes and transfered, and possibly an error
77 message. No reference to the internally used transmitter object
78 is made.
79 The result returned by the command is the empty string if it was
81 set to make an active connection, and the port the internal
82 transmitter object is listening on otherwise, i.e when it is
83 configured to connect passively. See also the package trans‐
84 fer::connect and the description of the method connect for where
85 this behaviour comes from.
86 transfer::transmitter stream file path host port ?arg...?
88 This method is like stream channel, except that the data con‐
89 tained in the file path is transfered.
90 OBJECT COMMAND
92 All objects created by the ::transfer::transmitter command have the
93 following general form:
94 objectName method ?arg arg ...?
96 The method method and its arg'uments determine the exact behav‐
97 ior of the command. See section Object methods for the detailed
98 specifications.
99 OBJECT METHODS
101 objectName destroy
102 This method destroys the object. Doing so while a transmission
103 is in progress will cause errors later on, when the transmission
104 completes and tries to access the now missing data structures of
105 the destroyed object.
106 objectName start
108 This method initiates the data transmission, setting up the con‐
109 nection first and then copying the information. The method will
110 throw an error if a transmission is already/still in progress.
111 I.e. it is not possible to run two transmissions in parallel on
112 a single object, only in sequence. Multiple transmitter objects
113 are needed to manage parallel transfers, one per transmission.
114 Errors will also be thrown if the configuration of the data
115 source is invalid, or if no completion callback was specified.
116 The result returned by the method is the empty string for an ob‐
118 ject configured to make an active connection, and the port the
119 object is listening on otherwise, i.e when it is configured to
120 connect passively. See also the package transfer::connect and
121 the description of the method connect for where this behaviour
122 comes from.
123 objectName busy
125 This method returns a boolean value telling us whether a trans‐
126 mission is in progress (True), or not (False).
127 OPTIONS
129 All transmitter objects support the union of the options supported by
130 their connect and data source components, plus two of their own. See
131 also the documentation for the packages transfer::data::source and
132 transfer::connect.
133 -blocksize int
135 This option specifies the size of the chunks to be transmitted
136 in one block. Usage is optional, its default value is 1024.
137 -command cmdprefix
139 This option specifies the command to invoke when the transmis‐
140 sion of the information has been completed. The arguments given
141 to this command are the same as given to the completion callback
142 of the command transfer::copy::do provided by the package trans‐
143 fer::copy.
144 -mode mode
146 This option specifies the mode the object is in. It is optional
147 and defaults to active mode. The two possible modes are:
148 active In this mode the two options -host and -port are relevant
150 and specify the host and TCP port the object has to con‐
151 nect to. The host is given by either name or IP address.
152 passive
154 In this mode the option -host has no relevance and is ig‐
155 nored should it be configured. The only option the ob‐
156 ject needs is -port, and it specifies the TCP port on
157 which the listening socket is opened to await the connec‐
158 tion from the partner.
159 -host hostname-or-ipaddr
161 This option specifies the host to connect to in active mode, ei‐
162 ther by name or ip-address. An object configured for passive
163 mode ignores this option.
164 -port int
166 For active mode this option specifies the port the object is ex‐
167 pected to connect to. For passive mode however it is the port
168 where the object creates the listening socket waiting for a con‐
169 nection. It defaults to 0, which allows the OS to choose the ac‐
170 tual port to listen on.
171 -socketcmd command
173 This option allows the user to specify which command to use to
174 open a socket. The default is to use the builtin ::socket. Any
175 compatible with that command is allowed.
176 The envisioned main use is the specfication of tls::socket. I.e.
178 this option allows the creation of secure transfer channels,
179 without making this package explicitly dependent on the tls
180 package.
181 See also section Secure connections.
183 -encoding encodingname
185 -eofchar eofspec
187 -translation transspec
189 These options are the same as are recognized by the builtin com‐
190 mand fconfigure. They provide the configuration to be set for
191 the channel between the two partners after it has been estab‐
192 lished, but before the callback is invoked (See method connect).
193 -string text
195 This option specifies that the source of the data is an immedi‐
196 ate string, and its associated argument contains the string in
197 question.
198 -channel handle
200 This option specifies that the source of the data is a channel,
201 and its associated argument is the handle of the channel con‐
202 taining the data.
203 -file path
205 This option specifies that the source of the data is a file, and
206 its associated argument is the path of the file containing the
207 data.
208 -variable varname
210 This option specifies that the source of the data is a string
211 stored in a variable, and its associated argument contains the
212 name of the variable in question. The variable is assumed to be
213 global or namespaced, anchored at the global namespace.
214 -size int
216 This option specifies the size of the data transfer. It is op‐
217 tional and defaults to -1. This value, and any other value less
218 than zero signals to transfer all the data from the source.
219 -progress command
221 This option, if specified, defines a command to be invoked for
222 each chunk of bytes transmitted, allowing the user to monitor
223 the progress of the transmission of the data. The callback is
224 always invoked with one additional argument, the number of bytes
225 transmitted so far.
226
228 One way to secure connections made by objects of this package is to re‐
229 quire the package tls and then configure the option -socketcmd to force
230 the use of command tls::socket to open the socket.
231 # Load and initialize tls
234 package require tls
235 tls::init -cafile /path/to/ca/cert -keyfile ...
236 # Create a connector with secure socket setup,
238 transfer::transmitter T -socketcmd tls::socket ...
239 ...
240
243 This package uses the TLS package to handle the security for https urls
244 and other socket connections.
245 Policy decisions like the set of protocols to support and what ciphers
247 to use are not the responsibility of TLS, nor of this package itself
248 however. Such decisions are the responsibility of whichever applica‐
249 tion is using the package, and are likely influenced by the set of
250 servers the application will talk to as well.
251 For example, in light of the recent POODLE attack [http://googleonli‐
253 nesecurity.blogspot.co.uk/2014/10/this-poodle-bites-exploiting-
254 ssl-30.html] discovered by Google many servers will disable support for
255 the SSLv3 protocol. To handle this change the applications using TLS
256 must be patched, and not this package, nor TLS itself. Such a patch
257 may be as simple as generally activating tls1 support, as shown in the
258 example below.
259 package require tls
262 tls::init -tls1 1 ;# forcibly activate support for the TLS1 protocol
263 ... your own application code ...
265
268 This document, and the package it describes, will undoubtedly contain
269 bugs and other problems. Please report such in the category transfer
270 of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please
271 also report any ideas for enhancements you may have for either package
272 and/or documentation.
273 When proposing code changes, please provide unified diffs, i.e the out‐
275 put of diff -u.
276 Note further that attachments are strongly preferred over inlined
278 patches. Attachments can be made by going to the Edit form of the
279 ticket immediately after its creation, and then using the left-most
280 button in the secondary navigation bar.
281
283 channel, copy, data source, secure, ssl, tls, transfer, transmitter
284
286 Transfer module
287
289 Copyright (c) 2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>
290tcllib 0.2 transfer::transmitter(n)