Abstract: The invention relates to a database system comprising a plurality of stations (101, 102, . . . , 10n) communicating with one another. The data that is inserted or updated in an originating station is backed up in at least one other station referred to as a “receiving” station. Means are provided so that data of a determined kind can be backed up synchronously or asynchronously on another station depending on whether or not a pre-established criterion is satisfied. For example, data that is modified progressively is backed up asynchronously until the data has finished being modified, and is backed up synchronously once modification has been finished. Such data may be routing data in a telecommunications system.

Abstract: The method combines two known types of access: access by pointer and access by variable. These two types of access are made compatible by particular rules of managing the locks: "hold", "read lock", and "write lock". Application to software platforms, in particular those used for telecommunications systems.

Abstract: A method of isolating a memory location containing an obsolete value of a variable, in a shared memory of a computer, said location being referenced via a pointer for access in the context of a first transaction, a lock called a "hold" being placed on said location and being assigned to a single task, said hold preventing any other task from accessing said location. The method of the invention does not free the location containing the obsolete value, but it isolates it from transactions other than that transaction which possesses the first pointer. This allows the task owning the first pointer to continue to access said obsolete value. However, any transaction can access another value of the variable, without waiting, because the descriptor of said variable directs said transactions to a location which is freely accessible and contains said other value.

Abstract: A method of assigning transaction identifiers assigns an identifier that is unique to each transaction, each transaction operating on data distributed across various stations. The method determines a first field of the identifier, having either a temporary value identifiable as such and unique to the station executing the application process that requested opening of the transaction if opening of the transaction is requested during an initialization phase or a value assigned by a first manager process specific to the station executing the requesting application process if opening of the transaction is requested after the initialization phase. The method also determines a second field having either a temporary value identifiable as such and unique to the set of stations if the opening of the transaction is requested during the initialization phase or a value assigned by a second manager process common to the set of stations if opening of the transaction is requested after the initialization phase.

Abstract: A transactional protocol allocates write intention locks at the time of access to a transaction modifying data stored in a memory. These locks do not prohibit the allocation of read locks to other transactions. The other transactions can therefore read the old values of the variables until the new values are written into the memory when the transaction is closed. The time for which reading of data being modified is prohibited is restricted to the time to write the new values into the memory. This protocol is of particular benefit if the memory is a volatile memory and the modified data is backed up in another, non-volatile memory. In this case, the protocol further keeps up-to-date a table stored in the non-volatile memory and containing the identifiers of current transactions. This table is used to ensure that the data is consistent after failure of the volatile memory and contributes to maintaining a minimal time of prohibition of reading of data being modified.