The application layer is specific code written to answer some particular questions about a system. The utility layer understands global system structures and language constructs to simplify the job of data analysis and presentation. The kernel understands event format and acts in behalf of applications to examine data collected by the accountant. The tripartite division of the analyst into the kernel, utility layer and applications layer simplifies the job of maintenance, use, and extension of the system. This means the event history log maintained by the accountant can be examined after particularly mysterious crashes to determine what the system had been doing lately. Object systems that use Metric continuously transmit event data. The standard format of events enables the accountant to receive events from different environments in a straightforward fashion, and makes the job of data handling easier for the analyst.Īnother advantage of Metric's simplicity is its economy of use: object system probes use about 100 microseconds to transmit data to the analyst. Most failures in the object system are unlikely to interfere with the functioning of the Metric system. Metric's robustness is a direct consequence of its simplicity, its simple communications protocols and the independence of its parts prevent failures in the Metric system from interfering with the user's object system. The contextual information intrinsic to an event supports its independence-the event carries with it the information necessary to describe what it is all about. In this way they provide context about what is happening in the system, and a succession of events provides a rich history of what has occurred in the system under study. Events are not counts of some system activity, they are a mini-snapshot of the state of the system when some activity begins or ends. Measurement events, small packets of standardly formatted measurement data, are used in a way that emphasizes their independence, history and context in a running system. The system is divided into three parts: object system probes that transmit measurement events, the accountant that receives and stores those events, and the analyst that manipulates the data for the user. Metric is used to instrument stand alone and distributed computer systems (it works in an environment of about 90 machines total and is used by about 15 machines). Metric is a distributed software measurement system that communicates measurement data over the PARC computer network, the Ethernet. The development support software for these microprocessors is based on a design methodology, according to which the support and application software is developed on a host general purpose computer, while software debugging and testing are performed directly on the targhet computer, with the aid of proper debugging tools. The paper discusses the requirements of an industrial design environment and shows how the problems of microprocessor programming are solved by means of an integrated software development support for 8-bit and 16-bit microprocessors. The use of these tools should be considered even in microprocessor applications in order to obtain the same advantages in this design area which is continuously growing in complexity. On large computers, many software tools are available in order to improve reliability of software packages and programmer productivity. It has been shown that the most of the total product cost is spent during the maintenance phase. Recently, software development issues have received a lot of attention. However, the use of microprocessors causes several problems concerning software development and programming in general. The use of VLSI technology allows an economical and efficient solution of typical exchange problems (i.e., fault tolerance, equipment flexibility). The introduction of microprocessors in the design of electronic switching systems is consistent with present tendencies toward distributed processing.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |