Architecture Reviews

Architecture reviews evaluate system designs against quality attributes, identifying risks and improvement opportunities before and after implementation.

Types of Reviews

Type	When	Focus
Design Review	Before implementation	Validate approach
Code Review	During development	Implementation quality
Production Review	After deployment	Operational concerns
Periodic Review	Scheduled (quarterly)	Drift and tech debt

Design Review Process

Pre-Review Checklist

## Design Review Checklist

### Documentation Required
- [ ] System design document
- [ ] Architecture diagrams (C4 or similar)
- [ ] Data model
- [ ] API specifications
- [ ] Non-functional requirements

### Areas to Cover
- [ ] Functional requirements met
- [ ] Scalability approach
- [ ] Security considerations
- [ ] Reliability/availability
- [ ] Operational concerns
- [ ] Cost implications
- [ ] Team capability alignment

Review Meeting Structure

## Architecture Review Agenda

**Project:** Order Processing Redesign  
**Date:** 2024-02-15  
**Duration:** 90 minutes  
**Attendees:** Architecture team, project leads

### Agenda

1. **Context Setting** (10 min)
   - Business drivers
   - Current pain points
   - Success criteria

2. **Design Walkthrough** (30 min)
   - High-level architecture
   - Key components
   - Data flow

3. **Deep Dives** (30 min)
   - Scalability approach
   - Failure scenarios
   - Security model

4. **Risk Discussion** (15 min)
   - Identified risks
   - Mitigation strategies

5. **Outcomes** (5 min)
   - Decisions made
   - Action items
   - Follow-up needed

Review Frameworks

ATAM (Architecture Tradeoff Analysis Method)

## ATAM Review Template

### 1. Business Drivers
- Primary business goals
- Key stakeholders
- Success metrics

### 2. Architecture Presentation
- System overview
- Key architectural approaches
- Mapping to business drivers

### 3. Quality Attribute Scenarios

| ID | Attribute | Scenario | Response Measure |
|----|-----------|----------|------------------|
| QA1 | Performance | 1000 concurrent users | Response < 200ms |
| QA2 | Availability | Database failure | Failover < 30s |
| QA3 | Security | SQL injection attempt | Request blocked |
| QA4 | Modifiability | Add payment provider | < 2 days effort |

### 4. Architecture Analysis

#### Sensitivity Points
- Database is single point of failure
- Cache invalidation complexity

#### Tradeoff Points
- Eventual consistency vs. performance
- Microservices complexity vs. scalability

#### Risks
| Risk | Impact | Likelihood | Mitigation |
|------|--------|------------|------------|
| Data inconsistency | High | Medium | Saga pattern |
| Vendor lock-in | Medium | High | Abstract integrations |

### 5. Results
- Approved with conditions
- Required changes before implementation
- Follow-up review date

Lightweight Review Template

## Quick Architecture Review

**System:** Payment Integration  
**Reviewer:** @jsmith  
**Date:** 2024-02-10

### Summary
Integrating new payment provider (Stripe) alongside existing PayPal.

### Strengths
✅ Clean abstraction layer for payment providers  
✅ Idempotency handling for retries  
✅ Comprehensive error mapping  

### Concerns
⚠️ No circuit breaker for external calls  
⚠️ Webhook signature validation missing  
⚠️ PCI compliance not addressed  

### Recommendations
1. Add Polly circuit breaker (P1)
2. Implement webhook signature verification (P1)
3. Document PCI scope and controls (P1)
4. Add payment provider health checks (P2)

### Decision
**Conditional Approval** - Address P1 items before production

Review Criteria by Quality Attribute

Performance Review

## Performance Checklist

### Data Access
- [ ] N+1 query problems identified
- [ ] Appropriate indexes defined
- [ ] Connection pooling configured
- [ ] Query result caching considered

### Caching
- [ ] Cache strategy defined
- [ ] Cache invalidation approach
- [ ] Cache hit ratio targets
- [ ] Cache failure handling

### Async Processing
- [ ] Long operations are async
- [ ] Background job strategy
- [ ] Queue depth monitoring

### Benchmarks
- [ ] Load testing performed
- [ ] Performance baselines established
- [ ] Bottlenecks identified

Security Review

## Security Checklist

### Authentication & Authorization
- [ ] Authentication mechanism appropriate
- [ ] Authorization at correct granularity
- [ ] Token/session management secure
- [ ] Password policies enforced

### Data Protection
- [ ] Sensitive data encrypted at rest
- [ ] TLS for all communications
- [ ] PII handling compliant
- [ ] Data retention policies

### Input Validation
- [ ] All inputs validated
- [ ] SQL injection prevented
- [ ] XSS prevention
- [ ] CSRF protection

### Dependencies
- [ ] Dependencies scanned for vulnerabilities
- [ ] Update process defined
- [ ] Supply chain security considered

Reliability Review

## Reliability Checklist

### Failure Handling
- [ ] Single points of failure identified
- [ ] Failover mechanisms in place
- [ ] Graceful degradation strategy
- [ ] Circuit breakers implemented

### Data Integrity
- [ ] Transaction boundaries correct
- [ ] Idempotency for retries
- [ ] Data validation at boundaries
- [ ] Backup and recovery tested

### Monitoring
- [ ] Health checks implemented
- [ ] Key metrics identified
- [ ] Alerting configured
- [ ] Runbooks prepared

Review Outcomes

public enum ReviewOutcome
{
    Approved,               // Proceed as designed
    ApprovedWithConditions, // Proceed after addressing items
    MajorRevisionRequired,  // Significant changes needed
    Rejected                // Fundamental issues, redesign needed
}

public class ReviewResult
{
    public ReviewOutcome Outcome { get; set; }
    public List<ReviewFinding> Findings { get; set; }
    public List<ActionItem> ActionItems { get; set; }
    public DateTime? FollowUpDate { get; set; }
}

public class ReviewFinding
{
    public string Area { get; set; }
    public FindingSeverity Severity { get; set; }
    public string Description { get; set; }
    public string Recommendation { get; set; }
}

public enum FindingSeverity
{
    Critical,  // Must fix before proceeding
    Major,     // Should fix before production
    Minor,     // Nice to have
    Note       // Informational
}

Post-Review Actions

## Review Follow-Up Template

**Review Date:** 2024-02-15  
**Project:** Order Processing  
**Outcome:** Approved with Conditions

### Required Actions (Before Production)

| # | Finding | Owner | Due Date | Status |
|---|---------|-------|----------|--------|
| 1 | Add circuit breaker | @dev1 | 2024-02-22 | In Progress |
| 2 | Implement rate limiting | @dev2 | 2024-02-25 | Not Started |
| 3 | Security scan | @security | 2024-02-20 | Complete |

### Recommended Actions (Post-Production)

| # | Finding | Owner | Due Date | Status |
|---|---------|-------|----------|--------|
| 4 | Performance optimization | @dev1 | 2024-03-15 | Planned |
| 5 | Documentation update | @tech-writer | 2024-03-01 | Not Started |

### Follow-Up Review
- **Date:** 2024-02-28
- **Focus:** Verify P1 items addressed
- **Attendees:** @reviewer, @tech-lead

Key Takeaways

1. Structured Process: Use checklists and templates consistently
2. Right Timing: Review before significant investment
3. Quality Attributes: Focus on non-functional requirements
4. Actionable Outcomes: Clear findings and owners
5. Follow Through: Track action items to completion

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💡 Flashcard

What is ATAM and when should it be used?

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✅ Answer

ATAM (Architecture Tradeoff Analysis Method) is a structured approach for evaluating software architectures against quality attributes. Use it for significant systems where understanding tradeoffs between quality attributes (performance vs. security, etc.) is critical.

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💡 Flashcard

What are the key quality attributes to review in an architecture?

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✅ Answer

Performance (response time, throughput), Security (authentication, data protection), Reliability (availability, fault tolerance), Scalability (handling growth), Maintainability (ease of change), and Operability (monitoring, deployment).

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