Question

As a second example, consider the communication paradigm referred to as queued RPC, as introduced in Rover [Joseph et al. 1997]. Rover is a toolkit to support distributed systems programming in mobile environments where participants in communication may become disconnected for periods of time. The system offers the RPC paradigm and hence calls are directed towards a given server (clearly space-coupled). The calls, though, are routed through an intermediary, a queue at the sending side, and are maintained in the queue until the receiver is available. To what extent is this time- uncoupled? Hint: consider the almost philosophical question of whether a recipient that is temporarily unavailable exists at that point in time.

Answer 1

Consider the given information:

It is given that the communication is made through queued Remote Procedure Call (RPC) and this is implemented through toolkit named as “Rover”.

This is the kit which supports the distributed system in a mobile environment. In this system, while the users are involved in the communication and they may be disconnected for a shorter period of time. For this, the RPC provides the paradigm and it act as intermediary queue on the sending side which stores calls made by the sender until the receiver becomes connected.

Extent of time-uncoupled property:

For the given case, let need to identify up to which extends the time-uncoupled is followed on communication paradigm.

The decision is based upon the point of interpretation of different lifetimes between sender and receiver on communication and the interpretations are as follows:

• If the interpretation is assumed that the receiver is not existed to receive the communication then, this is not the property of time uncoupled.

• If the interpretation is assumed that the receiver is present but not available at the given time which means that the server exists but disconnected due to some problem then, this follows property of time-uncoupled.