Practical Mod Perl

mod_perl embeds the popular programming language Perl in the Apache web server, giving rise to a fast and powerful web programming environment. Practical mod_perl is the definitive book on how to use, optimize, and troubleshoot mod_perl.

New mod_perl users will learn how to quickly and easily get mod_perl compiled and installed. But the primary purpose of this book is to show you how to take full advantage of mod_perl: how to make a mod_perl-enabled Web site as fast, flexible, and easily-maintainable as possible. The authors draw from their own personal experience in the field, as well as the combined experience of the mod_perl community, to present a rich and complete picture of how to set up and maintain a successful mod_perl site.

This book is also the first book to cover the "next generation" of mod_perl: mod_perl 2.0, a completely rewritten version of mod_perl designed for integration with Apache 2.0, which for the first time supports threads.

The book covers the following topics, and more:

• Configuring mod_perl optimally for your web site
• Porting and optimizing programs for a mod_perl environment
• Performance tuning: getting the very fastest performance from your site
• Controlling and monitoring the server to circumvent crashes and clogs
• Integrating with databases efficiently and painlessly
• Debugging tips and tricks
• Maximizing security

Written for Perl web developers and web administrators, Practical mod_perl is an extensive guide to the nuts and bolts of the powerful and popular combination of Apache and mod_perl. From writing and debugging scripts to keeping your server running without failures, the techniques in this book will help you squeeze every ounce of power out of your server. True to its title, this is the practical guide to mod_perl.

This book gives detailed instructions on how to use, optimize, and troubleshoot mod_perl. It shows how to get this Apache module running quickly and easily.

Important: The content in this book is for expired mod_perl technology, which hasn't been supported since 2010 and will not be useful unless you have to support an old server that uses mod_perl.

mod_perl embeds the popular programming language Perl in the Apache web server, giving rise to a fast and powerful web programming environment. Practical mod_perl is the definitive book on how to use, optimize, and troubleshoot mod_perl.

New mod_perl users will learn how to quickly and easily get mod_perl compiled and installed. But the primary purpose of this book is to show you how to take full advantage of mod_perl: how to make a mod_perl-enabled Web site as fast, flexible, and easily-maintainable as possible. The authors draw from their own personal experience in the field, as well as the combined experience of the mod_perl community, to present a rich and complete picture of how to set up and maintain a successful mod_perl site.

This book is also the first book to cover the "next generation" of mod_perl: mod_perl 2.0, a completely rewritten version of mod_perl designed for integration with Apache 2.0, which for the first time supports threads.

The book covers the following topics, and more:

• Configuring mod_perl optimally for your web site
• Porting and optimizing programs for a mod_perl environment
• Performance tuning: getting the very fastest performance from your site
• Controlling and monitoring the server to circumvent crashes and clogs
• Integrating with databases efficiently and painlessly
• Debugging tips and tricks
• Maximizing security

Written for Perl web developers and web administrators, Practical mod_perl is an extensive guide to the nuts and bolts of the powerful and popular combination of Apache and mod_perl. From writing and debugging scripts to keeping your server running without failures, the techniques in this book will help you squeeze every ounce of power out of your server. True to its title, this is the practical guide to mod_perl.

mod_perl embeds the popular programming language Perl in the Apache web server, giving rise to a fast and powerful web programming environment. Practical mod_perl is the definitive book on how to use, optimize, and troubleshoot mod_perl.

New mod_perl users will learn how to quickly and easily get mod_perl compiled and installed. But the primary purpose of this book is to show you how to take full advantage of mod_perl: how to make a mod_perl-enabled Web site as fast, flexible, and easily-maintainable as possible. The authors draw from their own personal experience in the field, as well as the combined experience of the mod_perl community, to present a rich and complete picture of how to set up and maintain a successful mod_perl site.

This book is also the first book to cover the next generation of mod_perl: mod_perl 2.0, a completely rewritten version of mod_perl designed for integration with Apache 2.0, which for the first time supports threads.

The book covers the following topics, and more: Configuring mod_perl optimally for your web sitePorting and optimizing programs for a mod_perl environmentPerformance tuning: getting the very fastest performance from your siteControlling and monitoring the server to circumvent crashes and clogsIntegrating with databases efficiently and painlesslyDebugging tips and tricksMaximizing securityWritten for Perl web developers and web administrators, Practical mod_perl is an extensive guide to the nuts and bolts of the powerful and popular combination of Apache and mod_perl. From writing and debugging scripts to keeping your server running without failures, the techniques in this book will help you squeeze every ounce of power out of yourserver. True to its title, this is the practical guide to mod_perl.

Stas Bekman is the author of The mod_perl Guide, the Open Source document that is the basis for this book. Stas is a member of the Apache Software Foundation and is a multiple speaker at the O'Reilly Open Source Conference. Stas is also a regular author for Perl.com.

Eric Cholet is a member of the Apache Software Foundation and the Paris Perl Mongers. He is technical director of Logilune, a Paris-based company that he co-founded in 1987, and a speaker at the O'Reilly Open Source Conference.

Preface; What You Need to Know; Who This Book Is For; How This Book Is Organized; Reference Sections; Filesystem Conventions; Apache and Perl Versions; Typographic Conventions; Command Interpreter Program (Shell) Conventions; Installing Perl Modules; How to Contact Us; Acknowledgments; Part I: mod_perl Administration; Chapter 1: Introducing CGI and mod_perl; 1.1 A Brief History of CGI; 1.2 The Apache 1.3 Server Model; 1.3 The Development of mod_perl 1.0; 1.4 Apache 1.3 Request Processing Phases; 1.5 References; Chapter 2: Getting Started Fast; 2.1 Installing mod_perl 1.0 in Three Steps; 2.2 Installing mod_perl on Unix Platforms; 2.3 Configuring and Starting the mod_perl Server; 2.4 Installing mod_perl for Windows; 2.5 Preparing the Scripts Directory; 2.6 A Sample Apache::Registry Script; 2.7 A Simple mod_perl Content Handler; 2.8 Is This All We Need to Know About mod_perl?; 2.9 References; Chapter 3: Installing mod_perl; 3.1 Configuring the Source; 3.2 Building mod_perl (make); 3.3 Testing the Server (make test); 3.4 Installation (make install); 3.5 Installation Scenarios for Standalone mod_perl; 3.6 Building mod_perl with Other Components; 3.7 Installing mod_perl with the CPAN.pm Interactive Shell; 3.8 Installing mod_perl on Multiple Machines; 3.9 Installation into a Nonstandard Directory; 3.10 How Can I Tell if mod_perl Is Running?; 3.11 General Notes; 3.12 References; Chapter 4: mod_perl Configuration; 4.1 Apache Configuration; 4.2 mod_perl Configuration; 4.3 The Startup File; 4.4 Apache Configuration in Perl; 4.5 Validating the Configuration Syntax; 4.6 The Scope of mod_perl Configuration Directives; 4.7 Apache Restarts Twice; 4.8 Enabling Remote Server Configuration Reports; 4.9 Tips and Tricks; 4.10 Configuration Security Concerns; 4.11 General Pitfalls; 4.12 References; Chapter 5: Web Server Control, Monitoring, Upgrade, and Maintenance; 5.1 Starting the Server in Multi-Process Mode; 5.2 Starting the Server in Single-Process Mode; 5.3 Using kill to Control Processes; 5.4 Using apachectl to Control the Server; 5.5 Validating Server Configuration; 5.6 Setuid root Startup Scripts; 5.7 Preparing for Machine Reboot; 5.8 Upgrading a Live Server; 5.9 Three-Tier Server Scheme: Development, Staging, and Production; 5.10 Web Server Monitoring; 5.11 Server Maintenance Chores; 5.12 References; Chapter 6: Coding with mod_perl in Mind; 6.1 Before You Start to Code; 6.2 Exposing Apache::Registry Secrets; 6.3 Namespace Issues; 6.4 Perl Specifics in the mod_perl Environment; 6.5 CHECK and INIT Blocks; 6.6 Apache::Registry Specifics; 6.7 Transition from mod_cgi Scripts to Apache Handlers; 6.8 Loading and Reloading Modules; 6.9 Handling the "User Pressed Stop Button" Case; 6.10 Handling Server Timeout Cases and Working with $SIG{ALRM}; 6.11 Generating Correct HTTP Headers; 6.12 Method Handlers: The Browse and See, Browse and View Example; 6.13 References; Part II: mod_perl Performance; Chapter 7: Identifying Your Performance Problems; 7.1 Looking at the Big Picture; 7.2 Asking the Right Questions; 7.3 References; Chapter 8: Choosing a Platform for the Best Performance; 8.1 Choosing the Right Operating System; 8.2 Choosing the Right Hardware; 8.3 References; Chapter 9: Essential Tools for Performance Tuning; 9.1 Server Benchmarking; 9.2 Perl Code Benchmarking; 9.3 Process Memory Measurements; 9.4 Apache::Status and Measuring Code Memory Usage; 9.5 Code Profiling Techniques; 9.6 References; Chapter 10: Improving Performance with Shared Memory and Proper Forking; 10.1 Sharing Memory; 10.2 Forking and Executing Subprocessesfrom mod_perl; 10.3 References; Chapter 11: Tuning Performance by Tweaking Apache's Configuration; 11.1 Setting the MaxClients Directive; 11.2 Setting the MaxRequestsPerChild Directive; 11.3 Setting MinSpareServers, MaxSpareServers, and StartServers; 11.4 KeepAlive; 11.5 PerlSetupEnv; 11.6 Reducing the Number of stat( ) Calls Made by Apache; 11.7 Symbolic Links Lookup; 11.8 Disabling DNS Resolution; 11.9 Response Compressing; 11.10 References; Chapter 12: Server Setup Strategies; 12.1 mod_perl Deployment Overview; 12.2 Standalone mod_perl-Enabled Apache Server; 12.3 One Plain and One mod_perl-Enabled Apache Server; 12.4 One Light Non-Apache and One mod_perl-Enabled Apache Server; 12.5 Adding a Proxy Server in httpd Accelerator Mode; 12.6 The Squid Server and mod_perl; 12.7 Apache's mod_proxy Module; 12.8 mod_rewrite Examples; 12.9 Getting the Remote Server IP in the Backend Server in the Proxy Setup; 12.10 Frontend/Backend Proxying with Virtual Hosts; 12.11 HTTP Authentication with Two Servers and a Proxy; 12.12 When One Machine Is Not Enough for Your RDBMS DataBase and mod_perl; 12.13 Running More than One mod_perl Server on the Same Machine; 12.14 SSL Functionality and a mod_perl Server; 12.15 Uploading and Downloading Big Files; 12.16 References; Chapter 13: TMTOWTDI: Convenience and Habit Versus Performance; 13.1 Apache::Registry PerlHandler Versus Custom PerlHandler; 13.2 Apache::args Versus Apache::Request::param Versus CGI::param; 13.3 Buffered Printing and Better print( ) Techniques; 13.4 Interpolation, Concatenation, or List; 13.5 Keeping a Small Memory Footprint; 13.6 Object Methods Calls Versus Function Calls; 13.7 Using the Perl stat( ) Call's Cached Results; 13.8 time( ) System Call Versus $r->request_time; 13.9 Printing Unmodified Files; 13.10 Caching and Pre-Caching; 13.11 Caching with Memoize; 13.12 Comparing Runtime Performance of Perl and C; 13.13 References; Chapter 14: Defensive Measures for Performance Enhancement; 14.1 Controlling Your Memory Usage; 14.2 Coding for a Smaller Memory Footprint; 14.3 Conclusion; 14.4 References; Chapter 15: Improving Performance Through Build Options; 15.1 Server Size as a Function of Compiled-in Features; 15.2 mod_status and ExtendedStatus On; 15.3 DYNAMIC_MODULE_LIMIT Apache Build Option; 15.4 Perl Build Options; 15.5 Architecture-Specific Compile Options; 15.6 References; Chapter 16: HTTP Headers for Optimal Performance; 16.1 Date-Related Headers; 16.2 Content Headers; 16.3 Content Negotiation; 16.4 HTTP Requests; 16.5 Avoiding Dealing with Headers; 16.6 References; Part III: Databases and mod_perl; Chapter 17: Databases Overview; 17.1 Volatile Databases; 17.2 Non-Volatile Databases; 17.3 References; Chapter 18: mod_perl Data-Sharing Techniques; 18.1 Sharing the Read-Only Data in and Between Processes; 18.2 Sharing Data Between Various Handlers; 18.3 References; Chapter 19: DBM and mod_perl; 19.1 mod_perl and DBM; 19.2 Resource Locking; 19.3 Flawed Locking Methods; 19.4 Locking Wrappers Overview; 19.5 Tie::DB_Lock; 19.6 Examples; 19.7 References; Chapter 20: Relational Databases and mod_perl; 20.1 Persistent Database Connections with Apache::DBI; 20.2 Improving Performance; 20.3 DBI Debug Techniques; 20.4 References; Part IV: Debugging and Troubleshooting; Chapter 21: Error Handling and Debugging; 21.1 Warnings and Errors Explained; 21.2 Debugging Code in Single-Server Mode; 21.3 Tracing System Calls; 21.4 Tracing mod_perl-Specific Perl Calls; 21.5 Debugging Perl Code; 21.6 Analyzing Dumped core Files; 21.7 Hanging Processes: Detection and Diagnostics; 21.8 Useful Debug Modules; 21.9 Looking Inside the Server; 21.10 References; Chapter 22: Troubleshooting mod_perl; 22.1 Configuration and Startup; 22.2 Code Parsing and Compilation; 22.3 Runtime; 22.4 Shutdown and Restart; Chapter 23: Getting Help and Online Resources; 23.1 How to Report Problems; 23.2 Mailing List Etiquette; 23.3 Resources; Part V: mod_perl 2.0; Chapter 24: mod_perl 2.0: Installation and Configuration; 24.1 What's New in Apache 2.0; 24.2 What's New in Perl 5.6.0-5.8.0; 24.3 What's New in mod_perl 2.0; 24.4 Installing mod_perl 2.0; 24.5 Configuring mod_perl 2.0; 24.6 Resources; Chapter 25: Programming for mod_perl 2.0; 25.1 Migrating to and Programming with mod_perl 2.0; 25.2 New Apache Phases and Corresponding Perl*Handlers; 25.3 I/O Filtering; Part VI: Appendixes; Appendix A: mod_perl Recipes; A.1 Emulating the Authentication Mechanism; A.2 Reusing Data from POST Requests; A.3 Redirecting POST Requests; A.4 Redirecting While Maintaining Environment Variables; A.5 Handling Cookies; A.6 Sending Multiple Cookies with the mod_perl API; A.7 Sending Cookies in REDIRECT Responses; A.8 CGI::params in the mod_perlish Way; A.9 Sending Email from mod_perl; A.10 mod_rewrite in Perl; A.11 Setting PerlHandler Based on MIME Type; A.12 Singleton Database Handles; A.13 Terminating a Child Process on Request Completion; A.14 References; Appendix B: Apache Perl Modules; B.1 Development-Stage Modules; B.2 Modules to Aid Debugging; B.3 Control and Monitoring Modules; B.4 Server Configuration Modules; B.5 Authentication-Phase Modules; B.6 Authorization-Phase Modules; B.7 Access-Phase Modules; B.8 Type Handlers; B.9 Trans Handlers; B.10 Fixup Handlers; B.11 Generic Content-Generation Modules; B.12 Application-Specific Content-Generation Modules; B.13 Database Modules; B.14 Toolkits and Frameworks for Content-Generation and Other Phases; B.15 Output Filters and Layering Modules; B.16 Logging-Phase Handlers; B.17 Core Apache Modules; B.18 Other Miscellaneous Modules; Appendix C: ISPs Providing mod_perl Services; C.1 Users Sharing a Single Web Server; C.2 Users Sharing a Single Machine; C.3 Giving Each User a Separate Machine (Colocation); C.4 Giving Each User a Virtual Machine; Appendix D: The Template Toolkit; D.1 Fetching and Installing the Template Toolkit; D.2 Overview; D.3 Typical Uses; D.4 Template Toolkit Language; D.5 Processing Templates; D.6 Apache/mod_perl Handler; D.7 Apache::Template Module; D.8 Hangman Application; D.9 References; Appendix E: The AxKit XML Application Server; E.1 Installing and Configuring AxKit; E.2 Your First AxKit Page; E.3 Dynamic Content; E.4 More XPathScript Details; E.5 XSLT; E.6 Putting Everything Together; E.7 More Reasons to Use AxKit; Appendix F: HTTP Status Codes; F.1 HTTP/1.0 Status Codes; F.2 HTTP/1.1 Status Codes; F.3 References; Colophon;