Reading from a URL, and reading Json, from your Tcl script

For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))

You can read from a URL in Tcl using the http package ... for example

  package require http

  set handle [::http::geturl http://www.wellho.co.uk/robots.txt]

And you can then collect the data:
  set body [::http::data $handle]

and the http status code:
  set stat [::http::ncode $handle]

and the headers:
  set headers [::http::meta $handle]

See [here] for the complete source code and sample output. The http::configure command gives a wide variety of configuration options too.

A further example - [here] - picks up json data via http, and converts it into a Tcl structure which it then displays. Of course, once you have the data, you can do just about anything with it.
(written 2015-03-12, updated 2015-03-15)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

T209 - Tcl/Tk - File and Directory Handling
  [779] The fragility of pancakes - and better structures - (2006-06-26)
  [785] Running external processes in Tcl and Tcl/Tk - (2006-06-29)
  [1407] Reading from another process in Tcl (pipes and sockets) - (2007-10-26)
  [1426] Buffering up in Tcl - the empty coke can comparison - (2007-11-10)
  [1467] stdout v stderr (Tcl, Perl, Shell) - (2007-12-10)
  [2467] Tcl - catching an error before your program crashes - (2009-10-22)
  [3192] Tcl - Some example of HOW TO in handling data files and formats - (2011-03-04)
  [3320] Reading the nth line from a file (Perl and Tcl examples) - (2011-06-09)
  [3429] Searching through all the files in or below a directory - Ruby, Tcl, Perl - (2011-09-09)
  [3617] The fileutil package and a list of file system commands in Tcl - (2012-02-18)
  [4523] Catching failed commands and not crashing the program in Tcl - (2015-10-10)
  [4524] Tcl - a new example for data reformatting - (2015-10-10)

T241 - Tcl/Tk - Tcl on the Web
  [1785] What is running on your network? (tcl and expect) - (2008-09-04)
  [2040] Error: Cant read xxxxx: no such variable (in Tcl Tk) - (2009-02-14)
  [2238] Handling nasty characters - Perl, PHP, Python, Tcl, Lua - (2009-06-14)
  [2429] Tcl scripts / processes on a web server via CGI - (2009-09-27)

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Using Object Oriented Tcl and the Tk toolkit together - real life example

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Server program written in Tcl using sockets

Some other Articles

Sockets, time handling and keyboard interrupt handling in C
Catching up on a week all in a single post (?)
Rail Conference, Nottingham
Server program written in Tcl using sockets
Reading from a URL, and reading Json, from your Tcl script
Using Object Oriented Tcl and the Tk toolkit together - real life example
Managing the window size (and layout) in Tcl/Tk
A new Tcl/tk example - a window to show system status
Test framework for TCL - Tcltest - some examples
Objects in Tcl - iTcl - updated first steps example

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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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