Reading client information and GET requests in Shiny

Shiny includes some very useful functionality that allows you to read information from a client's web browser, such as information from the URL (including GET search requests) and the size of plots in pixels.

All you need to do, as before, is run shinyServer() with a session argument. This causes, among other things, an object to be created that holds information about a client's session, named session$clientData.

The exact content of this object will depend on what is open on the screen. The following objects will always exist:

url_hostname   # hostname, e.g. localhost or chrisbeeley.net  
url_pathname = # path, e.g. / or /shiny  
url_port =     # port number (8100 for localhost, can optionally  
               # change when hosting, see chapter 5)  
url_protocol = # highly likely to be http:  
url_search =   # the...