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
• 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
• 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
  • Some Uses
  • A Warning
  • Conclusions
  • The My::Exception class in its entirety
  • Other Implementations

mod_perl Installation

• Installing mod_perl in 10 Minutes and 10 Command Lines
• 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
      • PERL_MARK_WHERE
      • 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 Installation with the CPAN.pm Interactive Shell
• Installing on multiple machines
• using RPM, DEB and other packages to install mod_perl
  • Static debian package
  • 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

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
  • <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
  • The Confusion with Global Variables in the 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
• 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 SQL DB and mod_perl
  • Servers' Requirements
  • The Problem
  • The Solution
    • Pros
    • Cons
  • Three Machines Model
• Do Not Run Everything on One mod_perl Server
• Do Not Put mod_ssl into a mod_perl Server
• Pros and Cons of Building mod_perl as DSO

Real World Scenarios

• 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
• One Light and One Heavy Server where All HTML is Perl-generated
  • Installation and Configuration
  • Tricks, Traps and Gotchas
• 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
  • 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
  • Use
  • 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
  • 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
• Testing the Code from the Shell
• I/O is different
• STDIN, STDOUT and STDERR streams
• Apache::print() and CORE::print()
• Global Variables Persistence
• Generating correct HTTP Headers
• NPH (Non Parsed Headers) scripts
• BEGIN blocks
• END 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
    • Developers Talk
    • Benchmarking a Graphic Hits Counter with Persistent DB Connections
    • Benchmarking Scripts with Execution Times Below 1 Second
    • Benchmarking PerlHandlers
  • Code Profiling Techniques
  • 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
  • Memory Swapping is Considered Bad
  • Increasing Shared Memory With mergemem
  • Forking and Executing Subprocesses from mod_perl
    • Spawning a Detachable Sub-Process
    • Gory Details About fork()
    • Executing system() in the Right Way
    • Avoiding Zombie Processes
  • OS Specific Parameters for Proxying
• Performance Tuning by Tweaking Apache Configuration
  • Tuning with ab - ApacheBench
  • Tuning with httperf
  • Tuning with the crashme Script
  • 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 versus Performance
  • Apache::Registry versus pure PerlHandler
    • The Light (Empty) Code
    • The Heavy Code
    • Processing and Results
    • Conclusions
  • CGI.pm versus Apache::Request
  • "Bloatware" modules
  • Apache::args versus Apache::Request::params
  • Using $|=1 Under mod_perl and Better print() Techniques.
  • Global vs Fully Qualified Variables
  • Avoid Importing Functions
  • Object Methods Calls Versus Function Calls
    • The Overhead with Light Subroutines
    • The Overhead with Heavy Subroutines
    • Are All Methods Slower than Functions?
  • Imported Symbols and Memory Usage
  • Concatenation or List
  • Using Perl stat() Call's Cached Results
• Apache::Registry and Derivatives Specific Notes
  • Be carefull with symbolic links
• Improving Performance by Prevention
  • Memory leakage
    • Reading In A Whole File
    • Copying Variables Between Functions
    • Work With Databases
  • Limiting the Size of the Processes
  • Keeping the Shared Memory Limit
  • Limiting the Resources Used by httpd Children
    • OS Specific notes
    • Debug
  • 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
    • Handling Timeouts
  • 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/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

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
  • 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 $x may be unavailable at - line 5.
  • Can't locate loadable object for module XXX
  • Can't locate object method "get_handlers"...
  • Missing right bracket at line ...
  • Can't load '.../auto/DBI/DBI.so' for module DBI
• Runtime
  • Preventing mod_perl Processes From Going Wild
  • Segfaults when using XML::Parser
  • My CGI/Perl Code Gets Returned as Plain Text Instead of Being Executed by the Webserver
  • Incorrect line number reporting in error/warn log messages
  • rwrite returned -1
  • Can't upgrade that kind of scalar ...
  • caught SIGPIPE in process
  • Client hit STOP or Netscape bit it!
  • Global symbol "$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
• Windows OS specific notes
  • Apache::DBI

Correct Headers - A quick guide for mod_perl users

• Correct Headers - A quick guide for mod_perl users
• 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
  • 3.) Avoiding dealing with them
• References and other literature
  • [1]
  • [2]
  • [3]
  • [4]
  • [5]
• VERSION
• AUTHOR

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

mod_perl and Relational Databases

• Why Relational (SQL) Databases
• Apache::DBI - Initiate a persistent database connection
  • Introduction
  • 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
• Flawed Locking Methods Which Must Not Be Used
• Lock 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 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
• 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
• Handling the 'User pressed Stop button' case
  • Detecting Aborted Connections
  • The Importance of Cleanup Code
    • Critical Section
    • Safe Resource Locking
    • Cleanup Code
• Handling Server Timeout Cases and Working with $SIG{ALRM}
• Looking inside the server
  • Apache::Status -- Embedded Interpreter Status Information
    • Minimal Configuration
    • Extended Configuration
    • Usage
    • Compiled Registry Scripts section seems to be empty.
  • mod_status
  • Apache::VMonitor -- Visual System and Apache Server Monitor
• Sometimes My Script Works, Sometimes It Does Not
• Code Debug
  • Locating and correcting Syntax Errors
  • Using Apache::FakeRequest to Debug Apache Perl Modules
  • Finding the Line Which Triggered the Error or Warning
  • Using print() for Debugging
  • Using print() and Data::Dumper for Debugging
  • The Importance of a Good Concise Coding Style
  • Introduction to the Perl Debugger
  • Interactive Perl Debugging under mod_cgi
  • Non-Interactive Perl Debugging under mod_perl
  • Interactive mod_perl Debugging
  • ptkdb and Interactive mod_perl Debugging
  • Debugging when Server Crashes on Startup before Writing to Log File.
• Debugging Hanging processes (continued)
  • Debugging core Dumping Code
• PERL_DEBUG=1 Build Option
• Apache::Debug
• Debug Tracing
• gdb says there are no debugging symbols
• Debugging Signal Handlers ($SIG{FOO})
• Code Profiling
• Devel::Peek
• How can I find out if a mod_perl script 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::GzipChain - compress HTML (or anything) in the OutputChain
• Apache::Filter - Alter the output of previous handlers
• Apache::Gzip - Auto-compress web files with Gzip
• Apache::PerlVINC - set a different @INC perl-location
• Apache::LogSTDERR
• Apache::RedirectLogFix
• Apache::SubProcess

Code Snippets

• Redirecting Errors to the Client Instead of error_log
• Emulating the Authentication Mechanism
• Caching POSTed Data
• Cache Control for Regular and Error Modes
• Convert a POST Request into a GET Request
• Redirect a POST Request, Forwarding the Content
• Reading POST Data, then Redirecting or Doing Something Else
• 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 Based On Query String and URI Implemented in Perl
• PerlTransHandler example
• 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
• 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
• Get help with Squid - Internet Object Cache
• Get help with CVS -- Concurrent Version Control

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
• ab - ApacheBench
• 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

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.
• Here is the Book-like version (PDF format). To read PDF files you can use: ghostview (gv), xpdf or acroread. You can use the pdf2ps utility to convert PDF to PostSscript format.

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