This paper presents an XML/TclTk implementation of a universal, user-configurable client that (1) reads user-programmed interconnections of distributed component programs as task instances, (2) dynamically renders an {interactive GUI of all interconnected components as a hierarchical taskflow, and (3) dynamically creates a schedule to execute component programs concurrently, serially, or not at all, depending on the user-defined runtime configuration of the taskflow topology. The client creates a taskflow-oriented programming environment, conceptually introduced in the companion paper and demonstrated in this paper.

The recursive schema of component instances is conveniently captured as an extension of XML in a {c}ollaborative {d}istributed {t}askflow {m}ark-up {l}anguage (cdtML) and consists of mainly two layers: (1) an encapsulated blackbox (single-task) or a whitebox (multi-task) layer, and (2) a task instance layer. The encapsulated task layer contains two parts: a definition layer and a body layer, with the definition layer serving as a readily accessible API for the task. A generic Tcl-XML parser reads both the cdtML schema and the user-created cdtML taskflow description and outputs a taskflow description in TclTk. This in turn generates the interactive GUI as the hierarchical taskflow, waiting for user inputs. User may choose to interact in any of the following ways: reconfigure the taskflow interconnections, view or edit data, descend/ascend the taskflow hierarchy, select the mode of execution, invoke the taskflow, abort the taskflow (if already executing), reset the state of the taskflow, etc.