What This Book Does Not Cover

Many factors affect application performance that are beyond the scope of this book. In the interest of full disclosure, we want to point these out:

• Database tuning: A relational database management system (RDBMS) requires a skilled database administrator (DBA) to ensure that the system is running optimally. This includes defining the configuration parameters of a database, including its growth parameters and the dimensions of its data pages. It also includes setting indexes on tables and ensuring that information can be retrieved from the database as fast as possible using efficient stored procedures. Finally, it includes making decisions on whether to cluster multiple database servers for optimum availability. These are complex topics that require specialized discussions, and they are not discussed in this book.

• Web-specific infrastructure/architecture: Web applications often run on a cluster of multiple servers, known as a server farm or Web farm. Load balancers are also frequently used for routing client requests so that the same server handles them. This book does not discuss how to set up these architectures. However, because Web farm architecture is so prevalent in many production systems, we frequently address optimization approaches that are specific to this architecture.

• Hardware (general): Clearly, hardware has a significant influence on the performance of the applications that it runs. Servers must be configured optimally to provide the right amount of processing power to its resident applications. Web applications and RDBMS systems alike run best on servers with strong processing power and high available memory. Hardware optimizations require a specialized focus and illustrations of real-world challenges that are not covered in this book.

• Network configuration: Web servers must obviously be networked in a way that makes them available to Internet-based clients . This requires skilled network administrators who can ensure that the Web server is installed where it can pipe high-bandwidth data to the outside world. At the same time, Web-based systems represent high-risk, vulnerable targets to hackers who want to penetrate the network or the Web application itself. This requires additional measures, such as the installation of firewalls and perimeter networks (also known as demilitarized zones or DMZs). These measures may indirectly impact the performance of a Web application, or they may influence its behavior (for example, by effectively placing a proxy between the Web server and its clients). Networking issues are not discussed in this book.