Abstract: A computer implemented process for identifying conflicts between policies for a method invocable by an object is described, in which the method is a member of at least one statically defined method grouping having a corresponding policy. The process comprises, for each method grouping, obtaining each method which is a member of the method grouping, associating therewith the corresponding method grouping policy, and comparing policies associated with methods which are members of two or more method groupings to identify conflicts.

Abstract: A method of providing a validatable data structure having a changeable part and an unchangeable part having respective content is described. The method comprises incorporating, in the unchangeable part, an identifier identifying the changeable part.

Abstract: A system is provided for disseminating resource allocation information from system resources to state-information observers comprising resource users and typically also at least one system resource manager. Each resource maintains state information about its identity and its allocation to one or more resource users. Each resource provides this information to a state-dissemination arrangement which disseminates it to each state-information observer. Each resource user uses the state information it receives from the state-dissemination arrangement to ascertain the resources allocated to it. Similarly, a system resource manager, when present, uses the state information it receives from the state-dissemination arrangement to ascertain the allocation of those resources that are of interest to the manager. A resource, resource user and resource manager for use in such a system are also provided.

Abstract: A system and method for automatically monitoring communications networks and for determining network configuration use data stream characterizations. The system comprises a plurality of measurement probes that passively probe the network and collect data packets carried by data streams in the network. The system further comprises characterization computational units that process the collected data packets and produce data stream characterizations from the collected data packets. The data stream characterizations represent individual data streams in an arbitrarily unique manner. The system still further comprises a configuration processing unit that compares data stream characterizations taken at different points in the network and determines data stream paths through the network based on data stream characterization matching.

Abstract: A system and method for distributing components across a plurality of resources is disclosed. Briefly described, one embodiment of distributing components across a plurality of resources in which the location of objects is limited by one or more constraints comprises providing a model which comprises at least one resource object and at least one component object, each object having at least one property which causes the object to attract or repel other objects, wherein properties allocated to the objects are dependent upon the constraints which apply to distribution of the components across the resources; distributing the objects within a model space; allowing the objects to move within the model space towards a stable solution; and distributing the components within the model space according to the distribution of the objects in the model space.

Abstract: A method is provided of combining first and second attribute sets each comprising at least one attribute/value pair by which a named attribute is assigned a value that comprises one of a end value and a further attribute set. The first attribute set is, for example, a resource description whilst the second attribute set defines specific attribute values. The method involves carrying out a merge operation that combines the attribute/value pairs of the first and second attribute sets according to their levels in their respective attribute trees with conflicts arising between attributes having the same path in each tree being resolved, on a top-down basis, according to predetermined rules.

Abstract: Data cells traversing an Asynchronous Transfer Mode (ATM) network (10) are passively monitored by probes at two spaced points (12,14). A filtering characteristic is applied to select cells comparatively infrequently, and timestamps or sequence numbers (or both) for the cells selected at each point are forwarded to a correlator (28). The correlator identifies similarities in the temporal patterns of intervals between timestamps received from each probe, and uses these similarities to identify and correlate timestamps relating to occurrence of the same cell at the two monitored points. The correlated timestamps are used to determine parameters indicative of the performance of the network, such as one-way delay, variation in that delay, and rate of cell loss.

Abstract: A configuration system for an application having a plurality of application components is described. The configuration system includes a configuration oracle/initiator that repeatedly asserts a desired state to the application components to operate in that desired state. The desired state is a predetermined state. The configuration oracle only asserts the desired state to the application components and does not control the manner in which each of the application components moves to the desired state. The configuration system also includes a configuration engine in each of the application components that causes the corresponding application components to move to the desired state upon receiving the state assertion of the desired state unless the configuration engine determines that the corresponding application component is already in the desired state. A method of configuring an application having a large number of application components is also described.

Abstract: The quality of service provided by a connection in transferring data units (19) between first and second points (A, B) across a network (10), is measured by a method involving monitoring the normal connection traffic at the first and second points (A, B) to detect the occurrence of the same events at each point (unit 22). An event is deemed to have occurred at a monitored network point when a predetermined set of criteria concerning one or more data units is satisfied by the connection data-unit traffic at the point concerned. Whenever an event is detected, an event report or "digest" is generated (unit 25), this digest including a signature based on the contents of the data units giving rise to the event. Digests from both monitored network points (A, B) are sent to a correlation unit (30) where digests relating to the occurrence of the same event at the two network points are matched up. The matched digest pairs are then passed to a measurement unit (31) to derive quality of service measurements.

Abstract: Monitoring apparatus is provided for monitoring an on-going input to detect and report events of a predetermined type as defined by a set of criteria stored by the apparatus. Detected events are reported in a report stream the data rate of which increases with the number of such events. The data rate of the report stream is regulated to lie within upper and lower bounds by changing the selectivity of the set of event-selection criteria. This changing of the selectivity of the critera is effected in such a manner that the events detected with more selective criteria constitute a subset of the events that would have been detected with a less selective criteria. In a preferred embodiment, changing the criteria selectivity is done by changing the length of a bit mask.