With the dramatic explosion of online information, the Internet is undergoing a transition from a data communication infrastructure to a global information utility. PDAs, wireless phones, Web-enabled vehicles, modem PCs, and high-end workstations can be viewed as appliances that "plug-in" to this utility for information. The increasing diversity of such appliances calls for an architecture for performance differentiation of information access. The key performance accelerator on the Internet is the caching and content distribution infrastructure. While many research efforts addressed performance differentiation in the network and on Web servers, providing multiple levels of service in the caching system has received much less attention. It has two main contributions. First, we describe, implement, and evaluate an architecture for differentiated content caching services as a key element of the Internet content distribution architecture. Second, we describe a control-theoretical approach that lays well-understood theoretical foundations for resource management to achieve performance differentiation in proxy caches. An experimental study using the Squid proxy cache shows that differentiated caching services provide significantly better performance to the premium content classes.

The increasing diversity of Internet appliances calls for an architecture for performance differentiation on information access. The World Wide Web is the dominant interface for information access today. Web proxy caching is the key performance accelerator in the Web infrastructure. While many research efforts have addressed performance differentiation in the network and on Web servers, providing multiple levels of service in proxy caches has received much less attention. This paper has two main contributions. First, we describe, implement and evaluate an architecture for differentiated content caching services as a key element of the Internet infrastructure. Second, we describe a control-theoretical approach that lays well-understood theoretical foundations for resource management to achieve performance differentiation in proxy caches. We describe our experiences with implementing the differentiated caching services scheme in Squid, a popular proxy cache used by many Internet service providers today. Experimental studies and analyses prove that differentiated caching services provide significant better performance to the premium content classes.

An emerging tapestry of computations will soon integrate systems around the globe. It will evolve without central control. Its complexity will be vast. We need new ideas, tools and methods to help map, understand and manage this tapestry. We contribute a light-weight architectural aspect that designers can use without compromising their own architectural preferences. Widespread use could help. The idea is for objects to provide Web-based interfaces to object-specific meta-data, state, and monitoring and control services. We discuss applications, implementation, scalability, performance, tradeoffs, and related work.