Abstract: A determination as to whether to store a data item at a computer connected to a distributed storage network of computers is made in dependence on a policy document associated with that data item. The policy document is constructed in accordance with a Document Type Definition expressed in extensible Markup Language (XML). This provides a more flexible method of system managed storage.

Abstract: Messages are generated by a first device which messages together have the purpose of identifying a predetermined number of devices which satisfy a test condition included in each message. These messages are sent respectively to on-line devices neighboring the first device. To ensure that no more devices than necessary are identified by the messages, each message includes a variable which is referred to as a token bucket which indicates the number of devices to be discovered by the message. Additionally, each message includes a unique identifier. When one device receives a discovery message sent from another device, it determines if it satisfies the test condition and if so it sends an acceptance message to the originating device, decrements the token bucket in the message and forwards on any remaining tokens to another neighbor. The process stops once all tokens have been disposed of in this way.