The embedded TclServer

The embedded TclServer

The readout software has embedded TclServer functionality. This means that it is possible for remote software to establish connections to the Readout software and issue arbitrary Tcl commands executed by Readout. This functionality allows one to:

• Write control panels that can run on systems remote to the Reaout program.
• Remotely update the values of state and run variables.
• Remotely inquire about the state of the system or the value of any of the variables (normal, const, state or run) defined by the software.

TclServer is enabled by using the -port switch on the command line that starts up the Readout. See Operating the readout software for the format of this switch.

Since remote software can perform arbitrary operations via the TclServer security is an issue. The TclServer initially comes up only accepting connections from the local system. The TclServer registers the serverauth command to control host based access to the TclServer.

The serverauth command can be used to:

• Enable access to the TclServer for a host based on its name or IP address:

  		 %  serverauth add hostorip
  	     

• Disallow access to a previously allowed host:

  	        %  serverauth remove hostorip
  	    

• Show the list of hosts that are authorized to connect to the TclServer:

  	        %  serverauth list
  	    

  Note that the list will be a set of doublets. Each doublet has the hostname and the correspond the IP address.

The embedded TclServer