[tcpsend] and [tcpconnect] will allow the recovery of information from remote servers, the usage of [tcpconnect] and [tcpsend] is mostly used to get data in the form of XML or JSON from another server so that the returned data can be used on the WebDNA site, stored in a database or used to communicate with a Payment Gateway.

To embed the results of a TCP session into a web page, use [tcpconnect] context in a template, with [tcpsend] contexts inside the [tcpconnect]. The TCPSend steps contained inside the context executes, and any returned value is displayed. Any WebDNA tags inside the context are first substituted for their real values before the TCPSend executes.

Each component inside the [tcpsend] context requires a "carriage return, line feed" at the end. This can be achieved in WebDNA by using the following string: [unurl]%0D%0A[/unurl]. The final line of the [tcpsend] context requires a DOUBLE "carriage return, line feed" ie: [unurl]%0D%0A%0D%0A[/unurl].

With the requirement of a secure connection by using &port=443&ssl=T in a request, the requirement for the addition of declaring the "HOST" within [tcpsend] becomes paramount.

Example WebDNA code:
Requesting json data without skipheader=t

[tcpconnect host=docs.webdna.us&port=443&ssl=T][!]
  [/!][tcpsend]GET /files/example.json HTTP/1.0[unurl]%0D%0A[/unurl][!]
    [/!]Host: docs.webdna.us[unurl]%0D%0A[/unurl][!]
    [/!][unurl]%0D%0A%0D%0A[/unurl][!]
  [/!][/tcpsend][!]
[/!][/tcpconnect]copy

Results:

HTTP/1.1 200 OK Date: Sun, 22 May 2022 22:57:11 GMT Server: Apache/2.4.41 (Ubuntu) MIME-Version: 1.0 Expires: Sun, May 22 2022 22:57:11 GMT Connection: close Content-Length: 264 Vary: Accept-Encoding Content-Type: text/html 
{"firstname":"John", "lastname":"Smith", "age":30, "car":null}, 
{"firstname":"Sally", "lastname":"Jones", "age":42, "car":"BMW"}, 
{"firstname":"Susan", "lastname":"Barlow", "age":29, "car":"Ford"}, 
{"firstname":"John", "lastname":"Lyons", "age":18, "car":"Toyota"}

If the expected return is a json object, then this result will fail due to the extra content before the json component.

Example WebDNA code:
Requesting json data WITH skipheader=t

[tcpconnect host=docs.webdna.us&port=443&ssl=T][!]
  [/!][tcpsend skipheader=t]GET /files/example.json HTTP/1.0[unurl]%0D%0A[/unurl][!]
    [/!]Host: docs.webdna.us[unurl]%0D%0A[/unurl][!]
    [/!][unurl]%0D%0A%0D%0A[/unurl][!]
  [/!][/tcpsend][!]
[/!][/tcpconnect]copy

Results:

{"firstname":"John", "lastname":"Smith", "age":30, "car":null}, 
{"firstname":"Sally", "lastname":"Jones", "age":42, "car":"BMW"}, 
{"firstname":"Susan", "lastname":"Barlow", "age":29, "car":"Ford"}, 
{"firstname":"John", "lastname":"Lyons", "age":18, "car":"Toyota"}

Now the returned json object can be used without error in javascript, or saved using WebDNA's [jsonstore]

Another example to get the change euro/dollar with an API:

The full URL is https://docs.webdna.us/files/example-exchange-rate.json?from=USD&to=EUR
For this one, we have to simulate a real browser
[text]varHOST=docs.webdna.us[/text]
[text]varGET=/files/example-exchange-rate.json?from=USD&to=EUR[/text]
[text]crlf=[unurl]%0D%0A[/unurl][/text]
[text]USexchange=[!]
  [/!][tcpconnect host=[varHOST]&port=443&ssl=T&timeout=20][!]
    [/!][tcpsend skipheader=T][!]
      [/!]GET [varGET] HTTP/1.0[crlf][!]
      [/!]Host: [varHOST][crlf][!]
      [/!]User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)[crlf][!]
      [/!][crlf][!]
    [/!][/tcpsend][!]
  [/!][/tcpconnect][!]
[/!][/text]

US$1.00 = [format .2f][middle startafter="rate":"&endbefore="][USexchange][/middle][/format] EURcopy

Results:
US$1.00 = 0.95 EUR