Contents   Index

Communication State Transitions

Well, if the bandwidth is so much greater when connected than otherwise, why do we even bother? Well, we want mobility and as they put in [24]:

"...with an increasing degree of mobility, the bandwidth of a connection, and as a consequence the amount of data which can be transferred in adequate time, decrease."

Figure 2.1: Different states

Furthermore, disconnected operation may be the result of a network or communication media failure that makes it impossible for the client to stay in contact with the server--an unvoluntary disconnection. The transitions between communication states are shown in Figure 2.1. The transitions between connected and weakly connected are not so common; normally the user of the mobile computer makes a voluntary disconnection before traveling from one place (domain) to another, and then reconnects on arrival. The use of mobile computers is discussed in Section 2.3. As mentioned earlier, (see page ) the mobile clients should experience no degradation of consistency when fully connected, and thus consistency should be restored upon reentering connected mode of operation.

  Contents   Index