How the design, placement and use of a public artefact facilitates, monitoring, cooperation and a global view on a task
1. The 'board': Story and Task cards (see Artefact as an audit trail) are pinned up in priority order on a pin board. The type, amount and order of the cards provides information to the group on what has been done, how much work is waiting of which types, and where this fits with other work to be completed. This provides a basic impression at-a-glance and more specific details on further inspection. Interaction with the board - e.g. selecting a card, re-ordering cards - provides information on what is going on, how the process is envisaged, who is doing what. This serves to provide the group with overall feedback on the project and to realise how individual work is coordinated with other work to do and the work of others. Developers take cards on at a time and work on them, passing them to the tracker when they are finished. When all the cards have gone (from the board and desks) the Iteration is finished.
2. The code:. Although not a single, public artefact the code is shared through applications that all can access. The developers see all parts of the code and can see what other people have done, through their machines. Again this promotes cooperation and an ability to see how ones own work relates to that of others in the working division of labour.
3. The Integration Flag: This flag (some people use a real flag) is raised to indicate that a pair are integrating the task they have just finished. This allows other members of the group to easily pick up when a pair have finished completing a task and are intergrating it with the rest of the group's work. Again this fosters a greater coordination and intergration of work.
In more traditional software development methods, such artifacts exist but as requirement and design documents that, while being public are not so visible, marked out and explicitly integrated as part of the work. Documents are often filed away and static in content, meaning on-going changes are not readily visible neither is the dynamic manner through which taks morph and change. In XP the relation of individual work to the group's is highlighted by the use of several public artefacts. Information is more ready for easy pick-up in the environment.
http://www.comp.lancs.ac.uk/computing/research/cseg/projects/pointer/patterns/publicArtefact/publicArtefact.html (legacy site)