Clients

Generally the purpose of the client is to moderate communication between participants. For most approaches it is helpful to introduce a dedicated machine, a server, as an intermediary. In such a setup, then, the purpose of clients is to intermediate between participants and the server. In particular clients have to display text and graphics on the screen, collect user actions (users fill in forms, click on buttons, click into pictures etc.), and send these actions to the server, possibly to request new text and graphics.

Choosing a www-browser as a client has several advantages:

• They are almost always available. Not only in dedicated laboratories, but also in general purpose computer pools.
• They often have professional quality.
• Many of them are free.
• The design idea of www-clients is very close to what we are doing in the laboratory. Elements that are efficient for Internet-shopping can easily be recycled to mimic economic models in the laboratory.

Representation of Text and Graphic with a www-browser:

• Text can be represented as HTML.

  Alternatively text could also be represented as pdf. This may allow even more control about the layout of the screen but it may consume more resources. We never found it necessary.

• Graphics can be represented as GIF or PNG.

• Java and Java-Script can be used to implement any other conceivable task. So far we did never need it but it is perhaps good to know that the possibility exists.