An Approach to Distribution of Object-Oriented Applications in Loosely Coupled Networks
针对松散耦合网络上的商业应用，提出一种两阶段方法：先生成类分片以保持封装和继承，再分配分片到站点以最小化站点间通信量，并通过原型验证可行性。
With the move to distributed systems and an increasing emphasis on the use of object-orientation for new system design, effective distribution of object-oriented applications is becoming an important concern for designers. Early research in this area has focused on object-clustering schemes for shared memory configurations that have limited value to business applications, which must be distributed over loosely coupled networks. These applications also exhibit the properties of simpler structural relationships and a large number of instances, demanding approaches closer to fragmentation and allocation instead of clustering. This paper develops an approach to distribution of object-oriented applications over geographically dispersed sites in loosely coupled networks–taking account of concerns such as encapsulation, inheritance, messaging, and implicit joins. The approach consists of two phases. First, we develop a scheme for generating class fragments, which ensures that encapsulation is not violated and inheritance is not stretched across sites. Second, considering the message-intensive operation of object-oriented systems, we devise models for allocation of class fragments to sites that minimize inter-site traffic. A nonarbitrary procedure to compile traffic volume estimates exploiting the notion of implicit joins in object-oriented applications provides the natural linkage between the two phases. A research prototype was implemented to establish feasibility of the proposals. Wedemonstrate usefulness of the approach by its application for distribution of a real-world information system.