Abstract: A tool (30) for graphically defining an expression is disclosed. The tool comprises a graphic user interface (GUI) component (31) and an expression generator component (32) adapted to read a graphic definition of an expression provided by a user through the GUI component. The GUI component is responsive to user input to define one or more tree structures comprising a hierarchical series of nodes, and one or more lists comprising a plurality of items, each list item being associated with respective node of an associated tree. The expression generator component analyzes the graphic definition and generates an expression based on the structure of the or each tree and any list items associated with respective nodes of a tree.

Abstract: A message broker data processing apparatus comprising: a unit for receiving published messages on a topic from a plurality of publisher applications; a unit for processing the received messages; and a unit for distributing the processed messages to a subscriber application; wherein the unit for receiving includes a plurality of publication point data processing nodes, each of which receives published messages on the topic from a publisher application.

Abstract: A method for allocating resources of a service provider to a plurality of users of the service provider in a data processing system wherein the resources are maintained in a resource pool when not allocated to a user and comprise a plurality of first and second resources, each second resource being associated with a first resource for use together with the associated first resource, and wherein, to invoke performance of a service by the service provider, a user issues a first resource request, requesting a first resource, one or more second resource requests, requesting one or more second resources, and, following receipt of the requested resources, issues a service request including the received first resource and at least one received second resource, requesting performance of the service, the method comprising steps of: dispensing dummy resources to a user in response to first and second resource requests, each dummy resource representing a resource requested by the user; and in response to the service req

Abstract: An improved graphics system for a graphical user interface in which a plurality of screen objects are displayed is disclosed. Conventional systems comprises targeting means for determining a screen object targeted by the pointer; and selection means for reading a pointer selection and for selecting a screen object. The invention is characterized by the selection means comprising means for selecting a screen object which has been continuously targeted for a predetermined time (pi).

Abstract: A message broker data processing apparatus has a unit for receiving published messages on a topic from a publisher application; a unit for processing the received messages; and a unit for distributing the processed messages to subscriber applications; wherein the unit for distributing includes a plurality of subscription point data processing nodes, a first subscription point data processing node distributes messages to a subscriber application which has previously registered a subscription request identifying the first subscription point data processing node with the broker apparatus.

Abstract: In a graphics system for a graphical user interface in which a plurality of screen objects are displayed, a method of targeting a screen object comprises determining a screen object targeted by a pointer and reading a pointer selection and selecting a targeted scream object. The method being characterized by generating, according to the proximity of the pointer position to a screen object, a weighting associated with each screen object, the weighting being in inverse proportion to the displayed size of the associated screen object; and wherein the determination is adapted to determine the targeted screen object according to the respective weightings associated with the scream objects.

Abstract: A message broker data processing apparatus for receiving messages from a sender application, processing the received messages and deciding which receiver application to forward the processed messages. An incoming stream of messages is received from a sender application, with each message being arranged as a tuple having at least one field. The incoming stream of messages is collated with data stored in a database, the data being also arranged as tuples having at least one field. The stream of message is processed so that a resultant stream of messages becomes directed to at least one receiving application.

Abstract: A value selector component for a graphical user interface control comprising: means for reading successive pointer movements when said user interface control is in focus; and means responsive to pointer movement in one direction to control a value and responsive to pointer movement in another direction to control a rate of change of the value in response to the movement in the one direction.

Abstract: A method for allocating resources of a service provider to a plurality of users of the service provider in a data processing system wherein the resources are maintained in a resource pool when not allocated to a user and comprise a plurality of first and second resources, each second resource being associated with a first resource for use together with the associated first resource, and wherein, to invoke performance of a service by the service provider, a user issues a first resource request, requesting a first resource, one or more second resource requests, requesting one or more second resources, and, following receipt of the requested resources, issues a service request including the received first resource and at least one received second resource, requesting performance of the service, the method comprising steps of: dispensing dummy resources to a user in response to first and second resource requests, each dummy resource representing a resource requested by the user; and in response to the service req

Abstract: A computer filing system includes a data access and allocation mechanism including a directory and a plurality of indexed data files or hash tables. The directory is preferably a radix tree including directory entries which contain pointers to respective ones of the hash tables. Using a plurality of hash tables avoids the whole database ever having to be re-hashed all at once. If a hash table exceeds a preset maximum size as data is added, it is replaced by two hash tables and the directory is updated to include two separate directory entries each containing a pointer to one of the new hash tables. The directory is locally extensible such that new levels are added to the directory only where necessary to distinguish between the hash tables. Local extensibility prevents unnecessary expansion of the size of the directory while also allowing the size of the hash tables to be controlled.

Abstract: Provided is a data processing system and a method for generating states of a model defined within a modelling application. The modelling application generates a state of the model based on the values of a number of input variables. A modification means alters the values of the input variables, and provides those altered values to the modelling application to cause a new state of the model to be generated. The modification means repeats the production of altered values such that a set of states of the model is generated. A display means produces a graphical representation of each state of the model in the set and displays the graphical representations on a display device.