Product Requirements Document (PRD): Layer 4 - JSON Validation

Document Information

• Product: JsonRemedy Layer 4 - JSON Validation
• Version: 1.0
• Date: January 2025
• Status: Draft
• Owner: JsonRemedy Development Team

Executive Summary

Layer 4 (JSON Validation) serves as the “fast path” validation layer in the JsonRemedy pipeline, providing high-performance JSON parsing for content that has been successfully repaired by previous layers or was already valid. This layer leverages the Jason library to attempt standard JSON parsing and either returns parsed results or passes malformed content to subsequent layers for more aggressive processing.

Product Overview

Purpose

Layer 4 acts as a performance optimization checkpoint that:

• Validates JSON syntax using industry-standard parsing (Jason)
• Provides immediate results for valid JSON (fast path)
• Efficiently identifies content requiring further processing
• Maintains pipeline integrity through proper error handling

Position in Pipeline

Layer 1 → Layer 2 → Layer 3 → Layer 4 → Layer 5
Content   Structural  Syntax     JSON      Tolerant
Cleaning   Repair     Normal.    Validation Parsing

Layer 4 receives input from Layer 3 (Syntax Normalization) and either:

• Success Path: Returns parsed JSON to the pipeline caller
• Continue Path: Passes malformed content to Layer 5 (Tolerant Parsing)

Goals and Objectives

Primary Goals

1. Performance Optimization: Provide fast parsing for valid JSON content
2. Standard Compliance: Ensure RFC 7159/ECMA-404 JSON compliance validation
3. Pipeline Efficiency: Minimize processing overhead for already-valid content
4. Error Classification: Accurately identify content requiring further processing

Success Metrics

• Performance: Valid JSON parsing < 100μs for inputs under 10KB
• Accuracy: 100% compliance with JSON standards
• Throughput: Handle 1000+ validations/second under load
• Memory: < 2x input size memory overhead during parsing

Target Users

Primary Users

• JsonRemedy Pipeline: Automated processing system
• API Developers: Processing external JSON responses
• Configuration Systems: Validating config files
• Data Processing Pipelines: Handling JSON data streams

Use Cases

1. Clean JSON Processing: Fast path for already-valid JSON
2. Repaired Content Validation: Validating output from previous layers
3. Quality Gate: Ensuring JSON compliance before final output
4. Performance Critical Paths: High-throughput JSON validation

Functional Requirements

Core Functionality

FR-001: Jason Integration

• Requirement: Integrate Jason library for JSON parsing
• Details:
  • Use Jason.decode/2 for parsing operations
  • Configure appropriate decode options
  • Handle all Jason error types gracefully
• Priority: P0 (Critical)

FR-002: Fast Path Processing

• Requirement: Provide optimized parsing for valid JSON
• Details:
  • Attempt Jason parsing first
  • Return parsed Elixir terms on success
  • Complete within performance thresholds
• Priority: P0 (Critical)

FR-003: Pass-Through Behavior

• Requirement: Pass malformed JSON to next layer
• Details:
  • Return {:continue, input, context} for parse failures
  • Preserve input string exactly
  • Maintain all context information
• Priority: P0 (Critical)

FR-004: Context Preservation

• Requirement: Maintain repair context from previous layers
• Details:
  • Preserve existing repairs list
  • Maintain options and metadata
  • Update layer processing status
• Priority: P0 (Critical)

Input/Output Specifications

Input Requirements

• Type: String (binary)
• Format: Potentially valid JSON or malformed content
• Size: Up to 100MB (configurable)
• Encoding: UTF-8

Output Specifications

• Success: {:ok, parsed_json, updated_context}
• Continue: {:continue, input_string, preserved_context}
• Error: {:error, error_reason} (rare, only for system failures)

Error Handling

EH-001: Jason Decode Errors

• Requirement: Handle all Jason.DecodeError cases
• Behavior: Convert to continue result, preserve input
• Examples: Syntax errors, invalid escapes, truncated JSON

EH-002: System Errors

• Requirement: Handle unexpected system failures
• Behavior: Return error tuple with descriptive message
• Examples: Memory exhaustion, timeout conditions

EH-003: Input Validation

• Requirement: Validate input parameters
• Behavior: Handle nil, non-string, oversized inputs gracefully

Non-Functional Requirements

Performance Requirements

NFR-001: Parsing Speed

• Requirement: Valid JSON parsing performance targets
• Metrics:
  • < 10μs for simple JSON (< 1KB)
  • < 100μs for medium JSON (1KB - 10KB)
  • < 1ms for large JSON (10KB - 100KB)
• Priority: P0 (Critical)

NFR-002: Memory Efficiency

• Requirement: Minimize memory overhead
• Metrics:
  • < 2x input size peak memory usage
  • No memory leaks on repeated calls
  • Efficient garbage collection
• Priority: P1 (High)

NFR-003: Throughput

• Requirement: Support high-volume processing
• Metrics:
  • 1000+ validations/second sustained
  • Linear scaling with CPU cores
  • Minimal resource contention
• Priority: P1 (High)

Reliability Requirements

NFR-004: Error Recovery

• Requirement: Graceful handling of all error conditions
• Metrics:
  • No crashes on malformed input
  • Proper error classification
  • Consistent behavior under stress
• Priority: P0 (Critical)

NFR-005: Thread Safety

• Requirement: Safe concurrent usage
• Metrics:
  • No shared mutable state
  • Race condition prevention
  • Deterministic results
• Priority: P0 (Critical)

Security Requirements

NFR-006: Input Safety

• Requirement: Safe processing of untrusted input
• Details:
  • Prevent JSON bomb attacks
  • Input size limits
  • Memory usage controls
• Priority: P1 (High)

Technical Specifications

Architecture Design

Layer Integration

@behaviour JsonRemedy.LayerBehaviour

@impl true
def process(input, context) do
  case Jason.decode(input) do
    {:ok, parsed} -> 
      {:ok, parsed, update_context(context)}
    {:error, _jason_error} -> 
      {:continue, input, context}
  end
rescue
  error -> {:error, format_error(error)}
end

Configuration Options

• :jason_options - Options passed to Jason.decode/2
• :fast_path_optimization - Enable/disable optimizations
• :validate_encoding - UTF-8 validation before parsing
• :timeout_ms - Maximum parsing time
• :max_input_size - Input size limits

Dependencies

• Jason: Primary JSON parsing library
• JsonRemedy.LayerBehaviour: Interface compliance
• String: UTF-8 validation utilities

Data Structures

Repair Context

%{
  repairs: [repair_action()],
  options: keyword(),
  metadata: %{
    layer4_processed: boolean(),
    validation_time_us: non_neg_integer(),
    parsed_successfully: boolean()
  }
}

Layer Result

{:ok, json_value(), repair_context()} |
{:continue, String.t(), repair_context()} |
{:error, String.t()}

Implementation Plan

Phase 1: Core Implementation (Week 1)

• Basic Jason integration
• LayerBehaviour implementation
• Core process/2 function
• Basic error handling

Phase 2: Optimization (Week 2)

• Performance optimizations
• Configuration system
• Memory efficiency improvements
• Concurrent access safety

Phase 3: Testing & Validation (Week 3)

• Comprehensive test suite (40+ tests)
• Performance benchmarks
• Security testing
• Integration testing

Phase 4: Documentation & Polish (Week 4)

• API documentation
• Usage examples
• Performance guide
• Error handling guide

Testing Strategy

Unit Testing

• Coverage Target: 95%+ line coverage
• Test Categories: Basic validation, error handling, edge cases
• Performance Tests: Timing and memory validation
• Security Tests: Malicious input handling

Integration Testing

• Pipeline Integration: Test with all other layers
• Real-world Data: Test with actual JSON from various sources
• Stress Testing: High-volume concurrent processing

Property-Based Testing

• JSON Invariants: Valid JSON always parses
• Performance Properties: Timing characteristics
• Memory Properties: No leaks or excessive usage

Quality Assurance

Acceptance Criteria

1. Functional: All 40 essential test cases pass
2. Performance: Meets all NFR timing requirements
3. Reliability: Zero crashes on malformed input
4. Integration: Seamless pipeline operation

Quality Gates

• Code Review: All code reviewed by 2+ developers
• Performance Review: Benchmarks meet requirements
• Security Review: Input safety validation
• Documentation Review: Complete and accurate docs

Risk Assessment

Technical Risks

Operational Risks

Success Criteria

Definition of Done

• All functional requirements implemented
• All non-functional requirements met
• 40+ essential tests passing
• Performance benchmarks satisfied
• Documentation complete
• Security review passed

Launch Criteria

• Integration tests with full pipeline pass
• Performance meets production requirements
• Error handling robustness validated
• Code review and approval complete

Future Considerations

Potential Enhancements

1. Custom Validation Rules: Extend beyond basic JSON syntax
2. Schema Validation: JSON Schema compliance checking
3. Streaming Support: Large file processing optimization
4. Caching: Result caching for repeated inputs

Maintenance Requirements

• Dependency Updates: Regular Jason version updates
• Performance Monitoring: Ongoing benchmark tracking
• Security Updates: Address any discovered vulnerabilities
• Documentation Updates: Keep current with changes

Appendices

Appendix A: Jason Library Integration

• Configuration options mapping
• Error type handling matrix
• Performance optimization settings

Appendix B: Performance Benchmarks

• Target timing specifications
• Memory usage profiles
• Concurrent processing metrics

Appendix C: Security Considerations

• Input validation strategies
• Attack vector prevention
• Resource limit enforcement

Document Approval

• Technical Lead Review
• Architecture Review
• Security Review
• Product Owner Approval

Last Updated: January 2025
Next Review Date: February 2025