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Redirection

Redirection policies enable automatic URL forwarding from one location to another with configurable HTTP status codes. The CDN system supports both permanent and temporary redirections using flexible pattern matching.

Redirection Configuration​

HTTP Status Codes​

Redirection policies support standard HTTP redirect codes:

  • 301 Permanent Redirect: Indicates permanent URL change for SEO preservation
  • 302 Temporary Redirect: Indicates temporary URL change without SEO impact

![Figure Needed] Screenshot showing redirection policy configuration with HTTP status code selection

URL Pattern Matching​

Prefix Matching​

Prefix matching applies redirection when the URL starts with a specified path:

  • Directory Redirection: /images applies policy to all files within the /images directory
  • Specific File Redirection: /files/mydownload.zip applies policy only to mydownload.zip

Regular Expression Matching​

Regular expressions provide flexible pattern matching for complex redirection scenarios:

  • File Extension Matching: /video/.+\.mp4 matches all .mp4 files in the /video directory
  • Pattern-Based Routing: Advanced URL transformation using regex patterns

Regular Expression Syntax​

Perl-Style Syntax​

The CDN policy system uses Perl-style regular expression syntax with specific rules and capabilities.

Reference Resource: Regular-Expressions.info provides comprehensive regex documentation.

Special Characters​

Regular expressions use special characters that require escaping when used literally:

. [ { } ( ) \ * + ? | ^ $

Escaping Example:

  • Pattern: /animated$files (incorrect - $ is special character)
  • Correct: /animated\$files (escaped with backslash)

Wildcard Patterns​

Wildcard matching uses dots with repetition qualifiers:

  • .*: Matches zero or more characters
  • .+: Matches one or more characters
  • .?: Matches zero or one character

Character Ranges​

Square brackets define character ranges for pattern matching:

  • Individual Characters: [123456789] matches any single digit 1-9
  • Range Notation: [1-9] equivalent to above
  • Mixed Ranges: [a-zA-Z0-9] matches letters and digits
  • With Quantifiers: [a-z]+ matches one or more lowercase letters

Alternation Patterns​

Alternation allows matching multiple options using pipe notation:

Syntax: (pattern1|pattern2|pattern3)

Example: \.(mp4|ogg|swf) matches files with .mp4, .ogg, or .swf extensions

URL Anchoring Requirements​

Path Matching Rules​

Regular expressions must match complete URL paths:

  • Leading Slash Required: Patterns must match the leading / in paths
  • Complete Path Matching: Pattern filename.txt will not match anything
  • Start-to-End Matching: Pattern /file matches http://host/file but not http://host/file.txt

Practical Examples​

Exact Path Matching​

  • Pattern: /files/august
  • Matches: Only /files/august (not subdirectories)
  • Different from Prefix: Does not match /files/august/document.pdf

Subdirectory Pattern Matching​

  • Pattern: /files/.+/index.html
  • Matches: All index.html files under /files/ directory regardless of subdirectory

File Extension Filtering​

  • Pattern: /files/august/.+\.(mp4|ogg|swf)
  • Matches: All .mp4, .ogg, or .swf files in /files/august/
  • Note: Backslash escapes the dot to treat it as literal character

Policy Precedence​

Multiple Match Resolution​

When multiple redirection policies match a URL, the most specific policy is applied:

  1. Prefix vs Regex: Compare prefix length to regex leading text length
  2. Prefix Comparison: Longer prefix takes precedence
  3. Regex Comparison: Longest leading text before patterns takes precedence
  4. Subnet and Location: Additional criteria for equivalent matches

Specificity Examples​

Prefix Precedence​

  • /files/images/ (more specific) vs /files/ (less specific)
  • Longer prefix wins

Regular Expression Precedence​

  • /files/images/.+\.jpg vs /files/.+\.jpg
  • First pattern has longer leading text (/files/images/)

Implementation Best Practices​

Testing Procedures​

  • Test redirection policies with sample URLs before deployment
  • Verify both matching and non-matching scenarios
  • Check redirect status codes in browser developer tools

SEO Considerations​

  • Use 301 redirects for permanent URL changes to preserve search rankings
  • Use 302 redirects for temporary changes or A/B testing
  • Avoid redirect chains that impact performance

Performance Optimization​

  • Minimize complex regex patterns for better performance
  • Use prefix matching when possible for simpler scenarios
  • Monitor redirect usage through analytics to optimize patterns