2.3 Summary

Ru-Brd

This chapter described two groups of design dimensions related to the successful development and deployment of networked applications. Service design dimensions affect the ways in which application services are structured, developed, and instantiated . Service configuration dimensions affect user or administrator abilities to vary the run-time placement and configuration of networked services after delivery and deployment.

Service design dimensions have a significant impact on how effectively applications use system and network resources. Efficient resource usage is closely linked to application response time, as well as to overall system performance and scalability. Performance is an important factor that's visible to end users. Though a coherent and modular design is less visible to end users, it's critical to a product's long- term success.

Good design simplifies maintenance and allows application functionality to evolve in response to market changes and competitive pressures without losing quality or performance. Fortunately, performance and modularity needn't be an either/or proposition. By carefully considering service design dimensions and applying ACE judiciously, you'll be able to create highly efficient and well-designed networked applications.

Even well-designed services and applications may need to adapt to a variety of deployment environments and user demands. Service configuration dimensions involve tradeoffs between design decisions associated with identifying a particular set of services and linking these services into the address space of one or more applications. To produce successful solutions, a networked application's flexibility must be weighed against its security, packaging, and complexity concerns.

When developing networked applications, the two sets of design dimensions in this chapter should be considered along with the dimensions described in Chapters 1 and 5 of C++NPv1. The ACE frameworks described in this book offer powerful tools to implement flexible and extensible designs with many combinations of tradeoffs and capabilities.

Ru-Brd