2.4 Assumptions and Preconditions

The following assumptions and preconditions apply to the transaction processing services protocols:

  • The system has to have access to a durable storage system where it can keep a log. The system holds state information for each running transaction in the log. Depending on the number of running transactions at a given time, the log size requirement can differ because the size of the log grows with the number of transaction states that it stores.

  • If the system spans across a computer network, the system has to be installed on all the computers that are involved.

  • The system has to be configured so that participants can access its services locally or remotely.

  • If the system components span across a computer network, the computers in the network has to be connected to each other via the durable network as described previously.

  • It is assumed that each transaction participant is trusted by the system. It is possible that a malicious participant can start several new transactions and never complete them, resulting in a filled log. Such a case forces the system to stop responding to new, incoming transaction requests until enough log space is available again.

Member protocols that are supported by the system, as listed in section 2.2, can have additional assumptions and preconditions when that protocol is being used. See the relevant member protocol specification for details.