Bandwidth Tolerance

Bandwidth Tolerance

INTRODUCTION

VISION
STATEMENT

THE PLATFORM
IS THE WEB

LOCATION
INDEPENDENCE

BANDWIDTH
TOLERANCE

EASY DATA
RETRIEVAL

YOU CAN TRUST
IT

IT JUST WORKS

Since the user is mobile, using different computers from time to time based on temporary expediency (such as geographical position, availability, or user interface style), inevitably some of these computers will be less well connected to the web than others. It's essential that the user can still get his work done when he's using poorly connected computers. Obviously, things will work less well when he's connected to the Internet via a 28.8K modem in Kuala Lumpur than when he's using an office PC on the same Ethernet as the server, but nevertheless they must still work well enough to be usable.

From the point of view of the user, this should mean that the system's behavior should match his reasonable expectations based on how he's connected. The system should work well when well-connected, without suffering because of the possibility of poor connections; and it should work adequately at other times.

From the point if view of system design, achieving this requires partitioning the work so as to place the minimum feasible demands on the low-bandwidth part of the connection. This is where a tool such as Java becomes essential. From this point of view, the primary purpose of Java is to let the system designer move computation into the user's workstation in order to move the interactive parts of the application closer to the user. Achieving bandwidth tolerance also requires designing the protocols so that the only data flowing over the low-bandwidth connection is data that the user needs to manipulate. For example, when the user displays an email message with large attached files, the files shouldn't be shipped to the workstation until (and unless) the user asks to see them.

The system designers must be continuously aware of the possiblity of low-bandwidth connectivity, and must engineer the system to tolerate it.