XPA Messaging provides seamless communication between Unix programs, including X, Tcl/Tk, and generic select() loops. It provides an easy way for users to communicate with these XPA-enabled programs by executing XPA client commands from a shell. Because XPA works both at the programming level and the shell level, it is a powerful tool for unifying any environment, offering flexibility in choosing the best level at which to access XPA services. A program becomes an XPA-enabled server by defining named points of public access through which data and commands can be exchanged with other client programs (and users). Using standard TCP sockets, XPA supports both single-point and broadcast messaging to and from these servers.
[incr Tcl] is a set of extensions to the Tcl language for object-oriented programming. [incr Tcl] (itcl) provides the extra language support needed to build large Tcl/Tk applications. It introduces the notion of objects, which act as building blocks for an application. Each object is a bag of data with a set of procedures or "methods" that are used to manipulate it. Objects are organized into "classes" with identical characteristics, and classes can inherit functionality from one another.
[incr Widgets] is an object-oriented mega-widget set which extends Tcl/Tk and is based on [incr Tcl] and [incr Tk]. This set of mega-widgets delivers many new, general purpose widgets like option menus, comboboxes, selection boxes, and various dialogs whose couterparts are found in Motif and Windows. Since [incr Widgets] is based on the [incr Tk] extension, the Tk framework of configuration options, widget commands, and default bindings is maintained. In other words, each [incr Widgets] mega-widget seamlessly blends with the standard Tk widgets. They look, act and feel like Tk widgets. In addition, all [incr Widgets] mega-widgets are object oriented and may themselves be extended, using either inheritance or composition.