41.6. The Event orderer/event builder API

The event builder itself is a loadable Tcl package rather than a program. This allows experiment designers to:

41.6.1. Starting the event builder/orderer

The example below is a Tcl script fragment that shows how to start the event builder. The code assumes that the environment variable DAQROOT has been set to the top installation directory of the NSCLDAQ being used (version 10.2 or later).

Example 41-3. Starting the event builder

lappend auto_path [file join $::env(DAQROOT) TclLibs]   (1)
package require EventBuilder        (2)

EVB::Start    ?name?                      (3)
Adds the Tcl Library directory of the NSCLDAQ to the list of directories searched for packages. This could also have been done by defining the TCLLIBS environment variable. TCLLIBS is a space separated list of directories trees that will be added to auto_path when tclsh or wish starts.
Loads the event builder Tcl package. This package defines the ::EVB:: namespace. The event builder API lives in this namespace to prevent name conflicts with your application variables and procs.
Starts the event builder. The event builder will use the DAQ Port manager to allocate a Tcp/IP server port as well as to advertise itself to potential clients. The optional name parameter specifies the event builder name. Note that if you provide a duplicate name,the script will attempt to pop up a Tk dialog prompting you to continue or not.

When this proc has returned, the event builder is listening for connections on that port and the client library will be able to find the event builder.

This proc must be called prior to any other procs in the EVB:: namespace.