[Cisco] - Call URL with a Cisco router (WGET) using IP SLA or TCL script

If you need to call a URL from a Cisco router (example: call a Web Service which will send an email...) as you would do using a WGET on a UNIX or Windows computer, here are two ways of doing it: 

1. Using an IP SLA

ip sla 10
http raw http://core-layer.com version 1.1
frequency 60
http-raw-request
  GET /script.html?param1=1 HTTP/1.1\r\n
  Connection: keep-alive\r\n
  Authorization: Basic YWRtaW46cGFzc3dvcmQ=\r\n
  \r\n
   exit

​The section http-raw-request will allow you to add HTTP headers if needed: for example, « Authorization: » header will allow the router to authenticate to the web page. That header si followed by authentication type (here « Basic ») and the string encoded in Base64: « username:password ». Which gives YWRtaW46cGFzc3dvcmQ= for admin:password .

You can then start the SLA using ip sla schedule 10...

​2. Using a TCL script

The same kind of request can be created using a TCL script (saved in router's flash memory for example) and then directly called for the CLI with tclsh flash:script.tcl arg1 arg2 arg3 ... 

Here is an example of TCL script saved in flash:

source "tmpsys:lib/tcl/http.tcl"

set arg1 [lindex $argv 0]

http::geturl " http://core-layer.com/script.html?param1=$arg1" -headers "Connection keep-alive Authorization \"Basic YWRtaW46cGFzc3dvcmQ=\""

​Here are a couple comments on that script
  - Many TCL script examples will tell you to add the reference to http this way:

package require http

​
Yet, Cisco stores librairies in « tmpsys:lib/tcl/» hence the following command:

source "tmpsys:lib/tcl/http.tcl"

  - To add HTTP headers you have to add parameter -headers which is then followed by headers formatted this way:

Header1 Value1 Header2 Value2 Header3 Value3 ...

So you should always have an even number of strings after parameter -headers . If a header requires a value with spaces in it you have to escape " using \" .