mod_perl Guide

Table of Contents:

Introduction. Incentives. Credits.

• What is mod_perl
  • mod_cgi
  • C API
  • Perl API
  • Apache::Registry
  • Apache::PerlRun
• What will you learn
• High-Profile Sites Running mod_perl
• References and Acknowledgments

Guide's Overview

• What's inside?

Perl Reference

• A Must Read!
• perldoc's Rarely Known But Very Useful Options
• Tracing Warnings Reports
• Variables Globally, Lexically Scoped And Fully Qualified
  • Symbols, Symbol Tables and Packages; Typeglobs
    • Lexical Variables and Symbols
  • Additional reading references
• my() Scoped Variable in Nested Subroutines
  • The Poison
  • The Diagnosis
  • The Remedy
• Understanding Closures -- the Easy Way
• When You Cannot Get Rid of The Inner Subroutine
  • Remedies for Inner Subroutines
• use(), require(), do(), %INC and @INC Explained
  • The @INC array
  • The %INC hash
  • Modules, Libraries and Program Files
  • require()
  • use()
  • do()
• Using Global Variables and Sharing Them Between Modules/Packages
  • Making Variables Global
  • Making Variables Global With strict Pragma On
  • Using Exporter.pm to Share Global Variables
  • Using the Perl Aliasing Feature to Share Global Variables
  • Using Non-Hardcoded Configuration Module Names
• The Scope of the Special Perl Variables
• Compiled Regular Expressions
• Exception Handling for mod_perl
  • Trapping Exceptions in Perl
  • Alternative Exception Handling Techniques
  • Better Exception Handling
    • A Little Housekeeping
    • An Exception Class
  • Catching Uncaught Exceptions
    • Using $SIG{__DIE__}
    • Overriding the Core die() Function
  • A Single UnCaught Exception Class
  • Some Uses
  • Conclusions
  • The My::Exception class in its entirety
  • Other Implementations

mod_perl Installation

• A Summary of a Basic mod_perl Installation
• The Gory Details
  • Source Configuration (perl Makefile.PL ...)
    • Configuration parameters
      • APACHE_SRC
      • DO_HTTPD, NO_HTTPD, PREP_HTTPD
      • Callback Hooks
      • EVERYTHING
      • PERL_TRACE
      • APACHE_HEADER_INSTALL
      • PERL_STATIC_EXTS
      • APACI_ARGS
      • APACHE_PREFIX
    • Environment Variables
      • APACHE_USER and APACHE_GROUP
    • Reusing Configuration Parameters
    • Discovering Whether Some Option Was Configured
    • Using an Alternative Configuration File
    • perl Makefile.PL Troubleshooting
      • "A test compilation with your Makefile configuration failed..."
      • Missing or Misconfigured libgdbm.so
      • About gdbm, db and ndbm libraries
      • Undefined reference to `PL_perl_destruct_level'
  • mod_perl Building (make)
    • make Troubleshooting
      • Undefined reference to 'Perl_newAV'
      • Unrecognized format specifier for...
  • Built Server Testing (make test)
    • Manual Testing
    • make test Troubleshooting
      • make test fails
      • mod_perl.c is incompatible with this version of Apache
      • make test......skipping test on this platform
      • make test Fails Due to Misconfigured localhost Entry
  • Installation (make install)
  • Building Apache and mod_perl by Hand
• Installation Scenarios for Standalone mod_perl
  • The All-In-One Way
  • The Flexible Way
  • Build mod_perl as a DSO inside the Apache Source Tree via APACI
    • libperl.so and libperl.a
  • Build mod_perl as a DSO outside the Apache Source Tree via APXS
• Installation Scenarios for mod_perl and Other Components
  • mod_perl and mod_ssl (+openssl)
  • mod_perl and mod_ssl Rolled from RPMs
  • mod_perl and apache-ssl (+openssl)
  • mod_perl and Stronghold
    • Note For Solaris 2.5 users
  • mod_perl and Raven SSL
    • Dynamic (DSO) mod_perl and Raven SSL Installation
    • Static mod_perl and dynamic Raven SSL Installation
  • mod_perl and mod_php
• mod_perl Installation with the CPAN.pm Interactive Shell
• Installing on multiple machines
• using RPM and other packages to install mod_perl
  • A word on mod_perl RPM packages
  • Getting Started
  • Compiling RPM source files
  • Mix and Match RPM and source
  • Installing a single apache+mod_perl RPM
  • Compiling libapreq (Apache::Request) with the RH 6.0 mod_perl RPM
  • Installing separate Apache and mod_perl RPMs
  • Testing the mod_perl API
• Installation Without Superuser Privileges
  • Installing Perl Modules into a Directory of Choice
  • Making Your Scripts Find the Locally Installed Modules
  • The CPAN.pm Shell and Locally Installed Modules
  • Making a Local Apache Installation
  • Manual Local mod_perl Enabled Apache Installation
    • Resource Usage
  • Local mod_perl Enabled Apache Installation with CPAN.pm
• Automating installation
• How can I tell whether mod_perl is running?
  • Checking the error_log
  • Testing by viewing /perl-status
  • Testing via telnet
  • Testing via a CGI script
  • Testing via lwp-request
• General Notes
  • Is it possible to run mod_perl enabled Apache as suExec?
  • Should I Rebuild mod_perl if I have Upgraded Perl?
  • Perl installation requirements
  • mod_auth_dbm nuances
  • Stripping Apache to make it almost a Perl-server
  • Saving the config.status Files with mod_perl, php, ssl and Other Components
  • What Compiler Should Be Used to Build mod_perl?
• OS Related Notes
• Pros and Cons of Building mod_perl as DSO

mod_perl Configuration

• Server Configuration
• Apache Configuration
  • Configuration Directives
  • .htaccess files
  • <Directory>, <Location> and <Files> Sections
  • How Directory, Location and Files Sections are Merged
  • Sub-Grouping of <Location>, <Directory> and <Files> Sections
  • Options Directive
• mod_perl Configuration
  • Alias Configurations
    • Running CGI, PerlRun, and Registry Scripts Located in the Same Directory
  • <Location> Configuration
  • Overriding <Location> Setting in "Sub-Location"
  • PerlModule and PerlRequire Directives
  • Perl*Handlers
  • The handler subroutine
  • Stacked Handlers
  • Perl Method Handlers
  • PerlFreshRestart
  • PerlSetVar, PerlSetEnv and PerlPassEnv
  • PerlSetupEnv
  • PerlWarn and PerlTaintCheck
  • MinSpareServers MaxSpareServers StartServers MaxClients MaxRequestsPerChild
• The Startup File
  • The Sample Startup File
  • What Modules You Should Add to the Startup File and Why
  • The Confusion with use() in the Server Startup File
• Apache Configuration in Perl
  • Usage
  • Enabling
  • Caveats
  • Verifying
  • Strict <Perl> Sections
  • Debugging
  • References
• Validating the Configuration Syntax
• Enabling Remote Server Configuration Reports
• Publishing Port Numbers other than 80
• Configuring Apache + mod_perl with mod_macro
• General Pitfalls
  • My CGI/Perl Code Gets Returned as Plain Text Instead of Being Executed by the Webserver
  • My Script Works under mod_cgi, but when Called via mod_perl I Get a 'Save-As' Prompt
  • Is There a Way to Provide a Different startup.pl File for Each Individual Virtual Host
  • Is There a Way to Modify @INC on a Per-Virtual-Host or Per-Location Basis.
  • A Script From One Virtual Host Calls a Script with the Same Path From the Other Virtual Host
  • the Server no Longer Retrieves the DirectoryIndex Files for a Directory
• Configuration Security Concerns
• Apache Restarts Twice On Start
• Knowing the proxy_pass'ed Connection Type
• Adding Custom Configuration Directives

Controlling and Monitoring the Server

• Restarting Techniques
• Server Stopping and Restarting
• Speeding up the Apache Termination and Restart
• Using apachectl to Control the Server
• Safe Code Updates on a Live Production Server
• An Intentional Disabling of Live Scripts
• SUID Start-up Scripts
  • Introduction to SUID Executables
  • Apache Startup SUID Script's Security
  • Sample Apache Startup SUID Script
• Preparing for Machine Reboot
• Monitoring the Server. A watchdog.
• Running a Server in Single Process Mode
• Starting a Personal Server for Each Developer
• Wrapper to Emulate the Server Perl Environment
• Server Maintenance Chores
  • Handling Log Files
    • Log Rotation
    • Non-Scheduled Emergency Log Rotation
• Swapping Prevention
• Preventing mod_perl Processes From Going Wild
  • All RAM Consumed

Choosing the Right Strategy

• Do it like I do it!?
• mod_perl Deployment Overview
• Alternative architectures for running one and two servers
  • Standalone mod_perl Enabled Apache Server
  • One Plain Apache and One mod_perl-enabled Apache Servers
  • One light non-Apache and One mod_perl enabled Apache Servers
• Adding a Proxy Server in http Accelerator Mode
• Implementations of Proxy Servers
  • The Squid Server
  • Apache's mod_proxy
• When One Machine is not Enough for RDBMS DataBase and mod_perl
  • Servers' Requirements
  • The Problem
  • The Solution
    • Pros
    • Cons
  • Three Machines Model
• Running More than One mod_perl Server on the Same Machine.
• SSL functionality and a mod_perl Server

Real World Scenarios

• Assumptions
• Standalone mod_perl Enabled Apache Server
  • Installation in 10 lines
  • Installation in 10 paragraphs
  • Configuration
• One Plain and One mod_perl enabled Apache Servers
  • Configuration and Compilation of the Sources.
    • Building the httpd_docs Server
    • Building the httpd_perl Server
  • Configuration of the servers
    • Basic httpd_docs Server Configuration
    • Basic httpd_perl Server Configuration
• Running Two webservers and Squid in httpd Accelerator Mode
• Running One Webserver and Squid in httpd Accelerator Mode
• mod_proxy
  • Concepts and Configuration Directives
    • ProxyPass
    • ProxyPassReverse
    • Security Issues
  • Buffering Feature
  • Setting the Buffering Limits on Various OSs
    • IOBUFSIZE Source Code Definition
    • ProxyReceiveBufferSize Configuration Directive
    • Hacking the Code
  • Caching Feature
  • Build Process
• Front-end Back-end Proxying with Virtual Hosts
• Getting the Remote Server IP in the Back-end server in the Proxy Setup
  • Build
  • Usage
  • Security
  • Caveats
  • mod_proxy_add_forward Module's Order Precedence
• HTTP Authentication With Two Servers Plus a Proxy
• mod_rewrite Examples
• Caching in mod_proxy

CGI to mod_perl Porting. mod_perl Coding guidelines.

• Document Coverage
• Before you start to code
• Exposing Apache::Registry secrets
  • The First Mystery
  • The Second Mystery
• Sometimes it Works, Sometimes it Doesn't
  • An Easy Break-in
  • Thinking mod_cgi
  • Regular Expression Memory
• Script's name space
• @INC and mod_perl
• Reloading Modules and Required Files
  • Restarting the server
  • Using Apache::StatINC for the Development Process
  • Using Apache::Reload
    • Register Modules Implicitly
    • Register Modules Explicitly
    • Special "Touch" File
    • Caveats
    • Availability
  • Configuration Files: Writing, Dynamically Updating and Reloading
    • Writing Configuration Files
    • Reloading Configuration Files
    • Dynamically updating configuration files
  • Reloading handlers
• Name collisions with Modules and libs
• More package name related issues
• __END__ and __DATA__ tokens
• Output from system calls
• Using format() and write()
• Terminating requests and processes, the exit() and child_terminate() functions
• die() and mod_perl
• Return Codes
• Testing the Code from the Shell
• I/O is different
• STDIN, STDOUT and STDERR streams
• Redirecting STDOUT into a Scalar
• Apache::print() and CORE::print()
• Global Variables Persistence
• Generating correct HTTP Headers
• NPH (Non Parsed Headers) scripts
• BEGIN blocks
• END blocks
• CHECK Blocks
• Command Line Switches (-w, -T, etc)
  • Warnings
  • Taint Mode
  • Other switches
• The strict pragma
• Passing ENV variables to CGI
• -M and other time() file tests under mod_perl
• Apache and syslog
• File tests operators
• Filehandlers and locks leakages
• Code has been changed, but it seems the script is running the old code
• The Script Is Too Dirty, But It Does The Job And I Cannot Afford To Rewrite It.
• Apache::PerlRun--a closer look
• Sharing variables between processes
• Transitioning from Apache::Registry to Apache handlers
  • Starting with mod_cgi Compatible Script
  • Converting into Perl Content Handler
  • Converting to use Apache Perl Modules
  • Conclusion

Performance Tuning

• The Big Picture
• System Analysis
  • Software Requirements
  • Hardware Requirements
• Essential Tools
  • Benchmarking Applications
    • Benchmarking Perl Code
    • Benchmarking a Graphic Hits Counter with Persistent DB Connections
    • Benchmarking Response Times
      • ApacheBench
      • httperf
      • http_load
      • the crashme Script
    • Benchmarking PerlHandlers
  • Code Profiling Techniques
  • Measuring the Memory of the Process
  • Measuring the Memory Usage of Subroutines
• Know Your Operating System
  • Sharing Memory
    • How Shared Is My Memory?
    • Calculating Real Memory Usage
    • Are My Variables Shared?
    • Preloading Perl Modules at Server Startup
    • Preloading Registry Scripts at Server Startup
    • Modules Initializing at Server Startup
      • Initializing DBI.pm
      • Initializing CGI.pm
  • Increasing Shared Memory With mergemem
  • Forking and Executing Subprocesses from mod_perl
    • Forking a New Process
    • Freeing the Parent Process
    • Detaching the Forked Process
    • Avoiding Zombie Processes
    • A Complete Fork Example
    • Starting a Long Running External Program
    • Starting a Short Running External Program
    • Executing system() or exec() in the Right Way
  • OS Specific Parameters for Proxying
• Performance Tuning by Tweaking Apache Configuration
  • Configuration Tuning with ApacheBench
  • Choosing MaxClients
  • Choosing MaxRequestsPerChild
  • Choosing MinSpareServers, MaxSpareServers and StartServers
  • Summary of Benchmarking to tune all 5 parameters
  • KeepAlive
  • PerlSetupEnv Off
  • Reducing the Number of stat() Calls Made by Apache
• TMTOWTDI: Convenience and Habit vs. Performance
  • Apache::Registry PerlHandler vs. Custom PerlHandler
  • "Bloatware" modules
  • Apache::args vs. Apache::Request::param vs. CGI::param
  • Using $|=1 Under mod_perl and Better print() Techniques.
  • Global vs. Fully Qualified Variables
  • Object Methods Calls vs. Function Calls
    • The Overhead with Light Subroutines
    • The Overhead with Heavy Subroutines
    • Are All Methods Slower than Functions?
  • Imported Symbols and Memory Usage
  • Interpolation, Concatenation or List
  • Using Perl stat() Call's Cached Results
• Apache::Registry and Derivatives Specific Notes
  • Be Careful with Symbolic Links
• Improving Performance by Prevention
  • Memory leakage
    • Reading In A Whole File
    • Copying Variables Between Functions
    • Work With Databases
  • Keeping the Shared Memory Limit
  • Limiting the Size of the Processes
  • Limiting Other Resources Used by Apache Child Processes
    • OS Specific notes
  • Limiting the Number of Processes Serving the Same Resource
  • Limiting the Request Rate Speed (Robot Blocking)
• Perl Modules for Performance Improvement
  • Sending Plain HTML as Compressed Output
  • Caching Components with HTML::Mason
• Efficient Work with Databases under mod_perl
  • Persistent DB Connections
    • Preopening Connections at the Child Process' Fork Time
    • Caching prepare() Statements
  • mod_perl Database Performance Improving
    • Analysis of the Problem
    • Optimizing Database Connections
    • Utilizing the Database Server's Cache
    • Eliminating SQL Statement Parsing
    • Conclusion
• Using 3rd Party Applications
  • Proxying the mod_perl Server
• Upload and Download of Big Files
• Apache/mod_perl Build Options
  • mod_perl Process Size as a Function of Compiled in C Modules and mod_perl Features
• Perl Build Options
  • -DTWO_POT_OPTIMIZE and -DPACK_MALLOC Perl Build Options
  • -Dusemymalloc Perl Build Option
• Architecture Specific Compile Options

Frequent mod_perl problems

• Coverage
• my() scoped variable in nested subroutines
• Segfaults caused by PerlFreshRestart

Warnings and Errors Troubleshooting Index

• General Advice
• Building and Installation
• Configuration and Startup
  • libexec/libperl.so: open failed: No such file or directory
  • install_driver(Oracle) failed: Can't load '.../DBD/Oracle/Oracle.so' for module DBD::Oracle
  • Invalid command 'PerlHandler'...
  • RegistryLoader: Translation of uri [...] to filename failed
  • "Apache.pm failed to load!"
• Code Parsing and Compilation
  • Value of $x will not stay shared at - line 5
  • Value of $x may be unavailable at - line 5.
  • Can't locate loadable object for module XXX
  • Can't locate object method "get_handlers"...
  • Missing right bracket at line ...
  • Can't load '.../auto/DBI/DBI.so' for module DBI
• Runtime
  • "exit signal Segmentation fault (11)" with mysql
  • foo ... at /dev/null line 0
  • Preventing mod_perl Processes From Going Wild
  • Segfaults when using XML::Parser
  • My CGI/Perl Code Gets Returned as Plain Text Instead of Being Executed by the Webserver
  • Incorrect line number reporting in error/warn log messages
  • rwrite returned -1
  • Can't upgrade that kind of scalar ...
  • caught SIGPIPE in process
  • Client hit STOP or Netscape bit it!
  • Global symbol "$foo" requires explicit package name
  • Use of uninitialized value at (eval 80) line 12.
  • Undefined subroutine &Apache::ROOT::perl::test_2epl::some_function called at
  • Callback called exit
  • Out of memory!
  • server reached MaxClients setting, consider raising the MaxClients setting
  • syntax error at /dev/null line 1, near "line arguments:"
  • Can't call method "register_cleanup" (CGI.pm)
• Shutdown and Restart
  • Evil things might happen when using PerlFreshRestart
  • Constant subroutine XXX redefined
  • Can't undef active subroutine
  • [warn] child process 30388 did not exit, sending another SIGHUP
  • Processes Get Stuck on Graceful Restart
  • httpd keeps on growing after each restart
• Windows OS specific notes
  • Apache::DBI

Issuing Correct HTTP Headers

• SYNOPSIS
• The Origin of this Chapter
• DESCRIPTION
• 1) Why Headers
• 2) Which Headers
  • 2.1) Date Related Headers
  • 2.1.1) Date
  • 2.1.2) Last-Modified
  • 2.1.3) Expires and Cache-Control
  • 2.2) Content Related Headers
  • 2.2.1) Content-Type
  • 2.2.2) Content-Length
  • 2.2.3) Entity Tags
  • 2.3) Content Negotiation
  • 2.3.1) Vary
• 3) Requests
  • 3.1) HEAD
  • 3.2) POST
  • 3.3) GET
  • 3.4) Conditional GET
• 4.) Avoiding Dealing with Headers
• References
  • [1]
  • [2]
  • [3]
  • [4]
  • [5]
• Other resources

Protecting Your Site

• The Importance of Your site's Security
• Illustrated Security Scenarios
  • Non authenticated access for internal IPs, Authenticated for external IPs
• Authentication code snippets
  • Forcing re-authentication
  • OK, AUTH_REQUIRED and FORBIDDEN in Authentication handlers
• Apache:Auth* modules

mod_perl and Relational Databases

• Why Relational (SQL) Databases
• Apache::DBI - Initiate a persistent database connection
  • Introduction
  • When should this module be used and when shouldn't it be used?
  • Configuration
  • Preopening DBI connections
  • Debugging Apache::DBI
  • Database Locking Risks
  • Troubleshooting
    • The Morning Bug
    • Opening connections with different parameters
    • Cannot find the DBI handler
    • Apache:DBI does not work
    • Skipping connection cache during server startup
    • Debugging code which deploys DBI
• mysql_use_result vs. mysql_store_result.
• Optimize: Run Two SQL Engine Servers
• Some useful code snippets to be used with relational Databases
  • Turning SQL query writing into a short and simple task
  • The My::DB module
  • My::DB Module's Usage Examples

mod_perl and dbm files

• Where and Why to use dbm files
• mod_perl and dbm
• Locking dbm Handlers and Write Lock Starvation Hazards
• Flawed Locking Methods Which Must Not Be Used
• Locking Wrappers Overview
• Tie::DB_Lock
• DB_File::Lock2

mod_perl for ISPs. mod_perl and Virtual Hosts

• ISPs providing mod_perl services - a fantasy or a reality
  • Virtual Servers Technologies
• Virtual Hosts in the guide

Debugging mod_perl

• Warning and Errors Explained
  • Curing The "Internal Server Error"
  • Helping error_log to Help Us
  • The Importance of Warnings
    • diagnostics pragma
• Handling the 'User pressed Stop button' case
  • Detecting Aborted Connections
  • The Importance of Cleanup Code
    • Critical Section
    • Safe Resource Locking and Cleanup Code
• Handling Server Timeout Cases and Working with $SIG{ALRM}
• Looking inside the server
  • Apache::Status -- Embedded Interpreter Status Information
    • Minimal Configuration
    • Extended Configuration
    • Usage
    • Compiled Registry Scripts section seems to be empty.
  • mod_status
  • Apache::VMonitor -- Visual System and Apache Server Monitor
• Sometimes My Script Works, Sometimes It Does Not
• Code Debug
  • Locating and correcting Syntax Errors
  • Using Apache::FakeRequest to Debug Apache Perl Modules
  • Finding the Line Which Triggered the Error or Warning
  • Using print() for Debugging
  • Using print() and Data::Dumper for Debugging
  • The Importance of a Good Concise Coding Style
  • Introduction to the Perl Debugger
  • Interactive Perl Debugging under mod_cgi
  • Non-Interactive Perl Debugging under mod_perl
  • Interactive mod_perl Debugging
  • ptkdb and Interactive mod_perl Debugging
  • Debugging when Server Crashes on Startup before Writing to Log File.
• Hanging Processes: Detection and Diagnostics
  • Hanging because of the OS Problem
  • An Example of Code that Might Hang a Process
  • Detecting hanging processes
  • Determination of the reason
    • Using the Perl Trace
    • Using the System Calls Trace
    • Using the Interactive Debugger
• Debugging Hanging processes (continued)
  • Debugging core Dumping Code
• PERL_DEBUG=1 Build Option
• Apache::Debug
• Debug Tracing
• gdb says there are no debugging symbols
• Debugging Signal Handlers ($SIG{FOO})
• Code Profiling
• Devel::Peek
• How can I find out if a mod_perl code has a memory leak
• Debugging your code in Single Server Mode
• Apache::DumpHeaders - Watch HTTP Transaction Via Headers
• Apache::DebugInfo - Log Various Bits Of Per-Request Data

Workarounds for some known bugs in browsers.

• Preventing QUERY_STRING from getting corrupted because of &entity key names
• IE 4.x does not re-post data to a non-port-80 URL

Apache::* modules

• Apache::Session - Maintain session state across HTTP requests
• Apache::DBI - Initiate a persistent database connection
• Apache::Watchdog::RunAway - Hanging Processes Monitor and Terminator
• Apache::VMonitor -- Visual System and Apache Server Monitor
• Apache::GTopLimit - Limit Apache httpd processes
• Apache::Request (libapreq) - Generic Apache Request Library
• Apache::RequestNotes - Allow Easy, Consistent Access to Cookie and Form Data Across Each Request Phase
• Apache::PerlRun - Run unaltered CGI scripts under mod_perl
• Apache::RegistryNG -- Apache::Registry New Generation
• Apache::RegistryBB -- Apache::Registry Bare Bones
• Apache::OutputChain -- Chain Stacked Perl Handlers
• Apache::Filter - Alter the output of previous handlers
• Apache::GzipChain - compress HTML (or anything) in the OutputChain
• Apache::Gzip - Auto-compress web files with Gzip
• Apache::PerlVINC - Allows Module Versioning in Location blocks and Virtual Hosts
• Apache::LogSTDERR
• Apache::RedirectLogFix
• Apache::SubProcess

Code Snippets

• Redirecting Errors to the Client Instead of error_log
• Reusing Data from POST request
• Redirecting POST Requests
• Redirecting While Maintaining Environment Variables
• Terminating a Child Process on Request Completion
• More on Relative Paths
• Watching the error_log File Without Telneting to the Server
• Accessing Variables from the Caller's Package
• Handling Cookies
• Sending Multiple Cookies with the Perl API
• Sending Cookies in REDIRECT Response
• Passing and Preserving Custom Data Structures Between Handlers
• Passing Notes Between mod_perl and other (non-Perl) Apache Modules
• Passing Environment Variables Between Handlers
• CGI::params in the mod_perl-ish Way
• Subclassing Apache::Request
• Sending Email from mod_perl
• A Simple Handler To Print The Environment Variables
• mod_rewrite in Perl
• URI Rewrite in PerlTransHandler
• Setting PerlHandler Based on MIME Type
• SSI and Embperl -- Doing Both
• Getting the Front-end Server's Name in the Back-end Server
• Authentication Snippets
• Emulating the Authentication Mechanism
• An example of using Apache::Session::DBI with cookies
• Using DESTROY to Finalize Output
• Setting Environment Variables For Scripts Called From CGI.
• Mysql Backup and Restore Scripts

Choosing an Operating System and Hardware

• Is it important?
• Choosing an Operating System
  • Stability and Robustness
  • Memory Management
  • Memory Leaks
  • Sharing Memory
  • Cost and Support
  • Discontinued Products
  • OS Releases
• Choosing Hardware
  • Machine Strength Demands According to Expected Site Traffic
    • Single Strong Machine vs Many Weaker Machines
  • Internet Connection
  • I/O Performance
  • Memory
  • CPU
  • Bottlenecks
    • Solving Hardware Requirement Conflicts
  • Conclusion

mod_perl Advocacy

• Thoughts about scalability and flexibility
• The boss, the developer and advocacy
• A summary of perl/cgi discussion at slashdot.org

Getting Help and Further Learning

• READ ME FIRST
• Contacting me
• Get help with mod_perl
• Get help with Perl
• Get help with Perl/CGI
• Get help with Apache
• Get help with DBI and SQL
• Get help with Squid - Internet Object Cache
• Get help with CVS -- Concurrent Version Control
• Get help with Performance and Scalability
• Get help with Unix OS flavors -- Unix OS related resources

Appendix A: Downloading software and documentation

• Coverage
• Perl
• CPAN Downloads
• Apache
• mod_perl
• Squid - Internet Object Cache
• thttpd - tiny/turbo/throttling HTTP server
• mod_throttle_access
• mod_proxy_add_forward
• httperf -- webserver Benchmarking tool
• http_load -- another webserver Benchmarking tool
• ab -- ApacheBench
• Daquiri -- yet another webserver Benchmarking tool
• High-Availability and Load Balancing Projects
  • mod_backhand -- Load Balancing for Apache
  • mod_redundancy
  • High-Availability Linux Project
  • lbnamed - a Load Balancing Name Server Written in Perl
  • Network Address Translation and Networks: Virtual Servers (Load Balancing)
  • Linux Virtual Server Project
  • Efficient Support for P-HTTP in Cluster-Based Web Servers
  • IP Filter
• Apache::Request
• DataBases
• libgtop

Changes:

• The Guide's Changes file.

Download:

• The latest CVS snapshots of the POD sources and the build script you can build the HTMLs from, are available from http://www.stason.org/guide-snapshots/.
• This release's HTML files, POD sources and build script are available from my directory at CPAN or its mirrors or search.cpan.org.
• Here is the Book-like version (PDF format).
  IMPORTANT: When you download a file with .gz extension many browsers do you a "favor" and uncompress it, but forget to remove the .gz extension. Just remove this extension if your tools complain that the file is broken if you try to uncompress it again.
  To read PDF files you can use: ghostview (gv), xpdf or acroread (with acroread you can search the text and us the hyperlinks). You can use the pdf2ps utility to convert PDF to PostSscript format.

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