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Hardware, Webservers and Mainframes

Question: Does the IBM 390 have the ability to implement the functionality of a web serverf?
Yes, an IBM 390 Mainframe, like other mainframes, has the ability to implement the functionality of a web server.
A web server essentially is a software application that serves web content (such as HTML pages, CSS files, images, JavaScript files, etc.) over the HTTP protocol to clients, typically web browsers. Most modern web servers support HTTPS, a secure variant of HTTP, which requires an additional SSL/TLS layer.
For IBM mainframes, a popular web server software is the IBM HTTP Server (IHS), which is based on Apache HTTP Server, a highly modular, open-source web server software. The IHS is able to serve static content, support CGI, forward requests to application servers, and implement many other features typical for a web server.
The mainframe also provides support for the WebSphere Application Server (WAS), which is more than just a web server. WAS is a full-fledged platform for running Java-based enterprise applications, including web applications. It can manage application runtime environments, provide load balancing and failover capabilities, handle large amounts of transactions, and maintain security and administrative services, among other things.
In terms of security, the IBM 390 Mainframe is equipped with various features to ensure secure web server operation. The mainframe environment is designed to support large-scale, mission-critical applications with robust security measures. The operating system z/OS, typically used in such mainframes, provides strong access controls, encryption capabilities, and security auditing tools. Moreover, the IBM Cryptographic Coprocessors can handle SSL/TLS encryption with minimal CPU overhead.
While the IBM 390 Mainframe can act as a web server, it's important to note that the strength of mainframe systems lies in their ability to process high volumes of transactions and provide robust, secure, and reliable service for mission-critical applications. Their full potential is often realized when they are used as back-end systems in combination with other, more front-facing web technologies.
IBM 390

Web Server Capacity

The explosive growth in the use of the World Wide Web has resulted in increased load on its constituent networks and servers, and stresses the protocols that the Web is based on. Improving the performance of the web has been the subject of much recent research, addressing various aspects of the problem such as better Web caching, HTTP protocol enhancements, better HTTP servers and proxies and server OS implementations.
To date most work on measuring Web software performance has concentrated on accurately characterizing Web server workloads in terms of request file types, transfer sizes, locality of reference in URLs requested and other related statistics. Some researchers have tried to evaluate the performance of Web servers and proxies using real workloads directly. However, this approach suffers from the experimental difficulties involved in non-intrusive measurement of a live system and the inherent irreproducibility of live workloads.
Recently, there has been some effort towards Web server evaluation through generation of synthetic HTTP client traffic, based on invariants observed in real Web traffic. Unfortunately, there are pitfalls that arise in generating heavy and realistic Web traffic using a limited number of client machines. These problems can lead to significant deviation of benchmarking conditions from reality and fail to predict the performance of a givenWeb server.
In a Web server evaluation testbed consisting of a small number of clientmachines, it is difficult to simulate many independent clients. Typically, a load generating scheme is used that equates client load with the number of client processes in the test system. Adding client processes is thought to increase the total client request rate. Unfortunately, some peculiarities of the TCP protocol limit the traffic generating ability of such a naive scheme. Because of this, generating request rates that exceed the server's capacity is nontrivial, leaving the effect of request bursts on server performance unevaluated. In addition, a naive scheme generates client traffic that has little resemblance in its temporal characteristics to real-world Web traffic. Moreover, there are fundamental differences between the delay and loss characteristics of WANs and the LANs used in testbeds. Both of these factors may cause certain important aspects of Web server performance to remain unevaluated. Finally, care must be taken to ensure that limited resources in the simulated client systems do not distort the server performance results.