Object-oriented software system construction

摘要

In a telecommunication switching system the telecommunication software is implemented by means of independent software components referred to as objects. The objects communicate with each other by messages and symbolic names only. A runtime system includes a runtime linker which registers the systems components and records a data pointer to the components data. To communicate with another object, a source object transmits an executable expression, called a message, to the runtime system. The message includes the symbolic name and the identity of the method of the destination object. The runtime system serves only a single processor or group of objects and calls the destination object, by means of the identity of the method and the data pointer if the destination object is within the group of objects served by the runtime system. In the case a destination object is located on another processor, the runtime system will broadcast the message to other processors. In each of the receiving processors, the runtime system searches its linker table for the symbolic name of the destination object of the message and if found calls the destination object on the basis of the method identification in the message and the data pointer information in the runtime linker. Interprocessor messages include a source processor designation and the run system of each of the processors records the name of the source processor and the symbolic name of the source object when an interprocessor message is received. This table is consulted before broadcasting a message to a non-resident destination object and a direct processor-to-processor communication is established, instead of a broadcast, if the symbolic name of the destination object is recorded together with the corresponding processor identification, in the destination table.