Our design approach has been implement a small number of features well, rather than attempting to provide every feature technically feasible. This enables us to provide the levels of ease of use and dependability usually found with information appliances.
The functionality supported by the system can be considered from two main perspectives: the perspective of the owner of the Hermes display and the perspective of a visitor to the Hermes display.
Functionality available to the Owner
The system provides the owner of the Hermes display with two key functions: the ability to create a message to appear on the display, and, the ability to read messages left by visitors.
Typically, the owner will create a message to appear on their Hermes display by entering some appropriate text using the web interface shown in figure 2. The web interface can also be used to upload a graphical image for display, such as an animated GIF.
Initially, only the web interface could be used by the owner of the Hermes display in order to create messages. However, after a short period of use it became clear that it is often only when closing the office door that one thinks to leave a message. For this reason we added a feature to enable the owner to create a freehand message by using an interface on the door display itself. This process does, however, require the owner to authenticate themselves with the system; this would typically be achieved by the owner docking his or her iButton or entering a username/password via a simple GUI on the Hermes display.
The owner can read his or her messages remotely via a web browser (see figure 3).

Functionality available to the Visitor
A visitor is not permitted to read the messages left by other visitors for the owner of a Hermes display. In this respect, the system clearly reduces the public visibility of messages left by visitors compared with the traditional post-it note. It will be interesting to observe, over a prolonged evaluation, the extent to which different users react positively or negatively to this feature.
In the current implementation, a visitor must be co-located with a Hermes display in order to leave a message. The user simply has to tap on a ‘leave note’ button on the Hermes display and then use the attached pen to ‘scribble’ a message on the touch sensitive display. Once the user taps on the ‘finished’ button the display on the unit is updated to reflect the fact that the owner has an additional message waiting to be read.
Another area that we are keen to explore is the notion of anonymity. As with its traditional counterpart, the Hermes system does not require visitors to authenticate themselves in order to leave a message.
However, if the user does authenticate themselves then their identity is associated with the message and can be used to simplify the task of replying to the message by the owner (as illustrated by the bottom message shown in figure 3).
If a visitor does authenticate themselves then he or she is able to view any private message that has been left by the owner.
Authentication also enables the visitor to remotely view any messages left on their own Hermes display. By supporting this feature we are hoping to explore the reaction of users to the sharing of their Hermes display.