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Overview
A relational database is a flat information space. Using the WaterkenTM RDB Webizer, you can carve this flat space into a web of resources. The web expresses your access control logic. Below are the resource webs for the Coffeebreak application.
An
<http://waterken.com/coffeebreak/ACoffeeEditor>
authorizes the holder to view and edit a coffee resource.
An
<http://waterken.com/coffeebreak/Accountant>
authorizes the holder to view both a weekly sales list and a price list.
Web diagram
In a web diagram, each circle represents a resource and each arrow represents a link. Some resources contain SQL for accessing the underlying database; other resources are purely navigational aids. As in the WWW, all links are unidirectional. Starting from a given resource, you can only traverse links emanating from that resource.
Capability URI
A link in a web diagram is implemented by a capability URI. A capability URI contains a random, 128 bit number. A random, 128 bit number is unguessable. It is computationally infeasible for an attacker to gain access to a resource identified by a capability URI. Accessing such a resource is only possible for users who have been given the capability URI. The WaterkenTM RDB Webizer includes an HTTP server. The server ensures that only requests received on a valid capability URI are delivered to the corresponding resource.
Auditing access control
Using a web diagram, you can determine exactly what resources are accessible from any entry point by
following the arrows. The holder of an
<Accountant>
capability can access the price list and weekly sales resources. The holder of a price list resource
capability, however, cannot access either weekly sales,
<Accountant>,
or any
<ACoffeeEditor>.
The coffeehouse gives its accountant a capability for the
<Accountant> resource.
They link to the price list resource from their public website, so that customers can see the
menu. The business gives a manager access to the
<ACoffeeEditor> resource
for each coffee, so that he or she can edit prices. This tutorial discusses all of these resources.
The next page describes installing the code.
Copyright 2002 - 2003 Waterken Inc. All rights reserved.
