J. Hu, I. Pyarale, and D. Schmidt. Applying the proactor pattern to high performance web services. In Proc. of the 10th International Conference on Parallel and Distributed Computing, Las Vegas, Nevada, October 1998.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....2 to be of any interest from the software designer point of view, it must be suitable for clean integration in the framework of XML based WWW applications. To clarify this point, we shall brie y introduce the use of an XML Access Control Processor (ACP) as a part of a componentbased Web service [5], where a set of reusable components are responsible of processing user requests. The sample UML Sequence Diagram shown in Figure 1 gives a general idea of the internal operation of our processor and of its integration in a Web server system. For the sake of simplicity, in this Section we shall ....

....of Figure 1 except the connection itself (1) take place on the server. Client side processing strategies (including client side caching, and caching proxy servers) have been traditionally used for HTML. However, clientside solutions have been found to be less apt at XML based Web services [5], where the contents to be transferred usually require extra processing. There may well be cases where negotiation could be envisioned between the client and the server as to the kinds of XML content transformations that are possible by the server and acceptable to the client; but it is clear that ....

J. Hu, I. Pyarale, and D. Schmidt. Applying the proactor pattern to high performance web services. In Proc. of the 10th International Conference on Parallel and Distributed Computing, Las Vegas, Nevada, October 1998.

....using blocking I O, event driven applications are at a disadvantage to obtain the desired behavior over this imperfect interface. Consequently, obtaining high performance requires that the application designer carefully manage event and thread scheduling, memory allocation, and I O streams [4, 9, 10, 21]. This monolithic event driven design is also difficult to modularize, as the code implementing each state is directly linked with others in the flow of execution. Nonblocking I O is provided by most OSs, but these interfaces typically do not scale well as the number of I O flows grows very ....

J. C. Hu, I. Pyarali, and D. C. Schmidt. Applying the Proactor pattern to high-performance Web servers. In Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems, October 1998.

.... monolithic event driven architecture described earlier. SEDA generalizes this approach by targeting a general purpose framework for highlyconcurrent applications. The JAWS web server [19] combines an eventdriven concurrency mechanism with a high level programming construct, the Proactor pattern [20], which is intended to simplify the development of event driven applications. Like SEDA, JAWS decouples event handling mechanisms from thread management; unlike SEDA, JAWS does not expose event queues or permit application specific load conditioning. Other systems have addressed aspects of the ....

J. C. Hu, I. Pyarali, and D. C. Schmidt. Applying the Proactor pattern to high-performance Web servers. In Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems, October 1998.

....concurrency is critical. Techniques often used by web servers, such as process per task or thread per task, do not scale to our needed degree of concurrency. Instead, we use asynchronous, event driven style of control ow in our DDS, similar to that espoused by modern high performance servers [5, 20] such as the Harvest web cache [8] and Flash web server [28] A convenient side e ect of this style is that layering is inexpensive and exible, as layers can be constructed by chaining together event handlers. Such chaining also facilitates interposition: a middleman event handler can be easily ....

J. C. Hu, I. Pyarali, and D. C. Schmidt. Applying the Proactor Pattern to High-Performance Web Servers. In Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems, Oct 1998.

....adopt an event driven approach to achieving robust high concurrency. Rather, they rely upon threads, and obtain scalability by growing the number of cluster nodes. The JAWS web server [13] combines an event driven concurrency mechanism with a high level programming construct, the Proactor pattern [14], which is intended to simplify the development of highly concurrent, event driven applications. While JAWS does not directly address fault isolation or clustering, the use of the Proactor pattern to describe the event driven programming model is a useful tool which could be applied to the task ....

James C. Hu, Irfan Pyarali, and Douglas C. Schmidt. Applying the Proactor Pattern to High-Performance Web Servers. In Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems, October 1998.

....to improve performance can be simplified significantly by leveraging OS features explicitly. For example, an optimized file I O system that automatically caches open files in main memory helps to reduce latency. Likewise, support for asynchronous event dispatching [9] and the Proactor pattern [8] can increase server throughput by reducing the context switching and synchronization overhead incurred from multi threading. This paper presents two complementary strategies for developing optimized Web servers. First, we present empirical results demonstrating that to achieve optimal ....

....of Web Server Performance JAWS is both a Web server and an OO framework [26] written in C that facilitates the development of flexible and adaptive high performance Web systems. The optimizations, OO design principles, and patterns used in JAWS are guided by results from our empirical analysis [6, 7, 8] of Web server performance bottlenecks over high speed ATM networks. Assuming sufficiently high network bandwidth and large file system caching, our experiments have identified the following determinants of Web server performance: Concurrency strategy and event dispatching: Request dispatching ....

[Article contains additional citation context not shown here]

James Hu, Irfan Pyarali, and Douglas C. Schmidt. Applying the Proactor Pattern to High-Performance Web Servers. In Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems. IASTED, October 1998.

....the drawbacks of synchronous multi threaded or reactive programming. To illustrate this pattern, consider a networking application that needs to perform multiple operations concurrently. For example, a highperformance Web server must concurrently process HTTP requests sent from multiple clients [1, 2]. Figure 1 shows a typical interaction between Web browsers and a Web server. When a user instructs a browser to open a URL, the browser 1: HTTP request Web Server Web Browser File System 3: read file 4: send file 2: parse request Figure 1: Typical Web Server Communication Software Architecture ....

J. Hu, I. Pyarali, and D. C. Schmidt, "Applying the Proactor Pattern to High-Performance Web Servers," in Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems, IASTED, Oct. 1998.

....the constraints of synchronous multithreaded or reactive programming. To illustrate these benefits, consider a networking application that needs to perform multiple operations concurrently. For example, a highperformance Web server must concurrently process HTTP requests sent from multiple clients [1, 2]. Figure 1 shows a typical interaction between Web browsers and a Web server. When a user instructs a browser to open a URL, the browser 1: HTTP request Web Server Web Browser File System 3: read file 4: send file 2: parse request Figure 1: Typical Web Server Communication Software Architecture ....

J. Hu, I. Pyarali, and D. C. Schmidt, "Applying the Proactor Pattern to High-Performance Web Servers," in Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems, IASTED, Oct. 1998.

....to improve performance can be simplified significantly by explicitly leveraging OS features. For example, an optimized file I O system that automatically caches open files in main memory helps to reduce latency. Likewise, support for asynchronous event dispatching [6] and the Proactor pattern [9] can increase server throughput by reducing context switching and synchronization overhead incurred from multi threading. This paper presents two complementary strategies for developing optimized Web servers. First, we present empirical results demonstrating that to achieve optimal performance, ....

....for Windows NT (JAWS NT) JAWS is both a Web server and an OO framework [26] written in C that facilitates the development of flexible and adaptive high performance Web systems. The optimizations, OO design principles, and patterns used in JAWS are guided by results from our empirical analysis [7, 8, 9] of Web server performance bottlenecks over highspeed ATM networks. Assuming sufficiently high network bandwidth and large file system caching, our experiments have identified the following determinants of Web server performance: Concurrency strategy and event dispatching: Request dispatching ....

[Article contains additional citation context not shown here]

James Hu, Irfan Pyarali, and Douglas C. Schmidt. Applying the Proactor Pattern to High-Performance Web Servers. In Proceedings of the 10th International Conference on Parallel and Distributed Computing and Systems. IASTED, October 1998.

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