- Table of Contents
- 1. Introduction
- 2. Data Storage and Access Models
- 3. Task Models
- 4. Data Posting Models
- 5. Properties of Common Database Designs
- 6. Design Considerations
- 7. Conclusions
- 8. More Information
1. Introduction
In most software control applications, the question arises as to how data should be collected and transmitted among the software tasks that make up the control system. While some systems use a monolithic approach, performing all data acquisition, processing and user interface within a single task, this is generally considered to be an inferior design leading to limitations in performance and flexibility. Consequently, a well-designed modular application will be faced with the need to communicate process information among several tasks, each with different data requirements. This white paper explains some of the considerations involved in choosing a data model.
 | We focus here on real-time data, which often gets updated hundreds of times per second, in contrast to data in information systems and relational databases that is typically updated and accessed in time spans of minutes, hours, or days. A database used to handle real-time data is like a hub--a lively transfer point where data can be updated and sent virtually instantaneously, from and to many processes at the same time. At Cogent Real-Time Systems, Inc. we use the term "datahub" for this kind of database, and we refer to our datahub as the "Cascade DataHub." |