Context Mapping Skill

Map relationships between bounded contexts using Domain-Driven Design context mapping patterns. Produces Context Mapper DSL (CML) output and integration strategy recommendations.

When to Use This Skill

Keywords: context mapping, bounded contexts, upstream, downstream, ACL, anti-corruption layer, shared kernel, customer supplier, open host service, published language, conformist, partnership, CML, integration patterns, domain relationships

Use this skill when:

• After event storming when bounded contexts have been identified
• Defining integration strategies between domains
• Documenting domain relationships and dependencies
• Generating context map diagrams (Mermaid/PlantUML)
• Creating Context Mapper DSL (CML) output
• Planning team boundaries based on context relationships
• Identifying where anti-corruption layers are needed

Context Mapping Patterns

Eight strategic DDD patterns for defining context relationships:

Symmetric Patterns (Equal Relationship)

Pattern	Abbrev	Description	Use When
Shared Kernel	SK	Shared code/model between contexts	Two contexts need identical domain logic
Partnership	P	Equal collaboration, mutual dependency	Teams co-evolve, no clear upstream/downstream

Asymmetric Patterns (Upstream/Downstream)

Pattern	Abbrev	Description	Use When
Customer/Supplier	C/S	Upstream supplies, downstream consumes	Clear provider/consumer relationship
Conformist	CF	Downstream adopts upstream model	Downstream team has no leverage to negotiate
Anti-Corruption Layer	ACL	Downstream translates upstream model	Upstream model doesn't fit downstream needs
Open Host Service	OHS	Upstream provides formal API	Multiple consumers need standardized access
Published Language	PL	Standardized API format (OpenAPI, etc.)	Cross-team communication requires contract

No Integration

Pattern	Abbrev	Description	Use When
Separate Ways	SW	No integration, independent evolution	Contexts have no meaningful relationship

For detailed pattern descriptions with examples: See references/pattern-catalog.md

Pattern Selection Guide

Decision Flow

Do the contexts share code or data model?
├── Yes → Shared Kernel [SK]
└── No → Is there a clear data/service flow?
    ├── No → Do teams collaborate equally?
    │   ├── Yes → Partnership [P]
    │   └── No → Separate Ways [SW]
    └── Yes → Identify Upstream (provider) and Downstream (consumer)
        └── Can downstream influence upstream's model?
            ├── No → Does upstream model fit downstream needs?
            │   ├── Yes → Conformist [CF]
            │   └── No → Anti-Corruption Layer [ACL]
            └── Yes → Customer/Supplier [C/S]
                └── Does upstream serve multiple consumers?
                    ├── Yes → Add Open Host Service [OHS]
                    │   └── Needs contract? → Add Published Language [PL]
                    └── No → Basic C/S is sufficient

For detailed selection criteria: See references/pattern-selection.md

Context Mapper DSL (CML)

Basic Syntax

ContextMap <MapName> {
    contains <Context1>
    contains <Context2>

    // Asymmetric: Downstream [D] <- Upstream [U]
    <DownstreamContext> [D,<patterns>]<-[U,<patterns>] <UpstreamContext>

    // Symmetric: Both sides equal
    <Context1> [<patterns>]<->[<patterns>] <Context2>
}

Notation Reference

Symbol	Meaning
[D]	Downstream context
[U]	Upstream context
<-	Asymmetric relationship (upstream to downstream)
<->	Symmetric relationship
[D,C]	Downstream + Customer
[U,S]	Upstream + Supplier
[D,ACL]	Downstream with Anti-Corruption Layer
[U,OHS,PL]	Upstream with Open Host Service + Published Language
[SK]	Shared Kernel (symmetric)
[P]	Partnership (symmetric)
[CF]	Conformist

For complete CML syntax: See references/cml-syntax.md

Multi-Mode Execution

Mode Selection

Mode	Description	Use When
full	Systematically analyze all bounded contexts	Comprehensive mapping, larger domains
quick	Identify obvious relationships only	Quick overview, small domains
guided	Interactive, confirm each relationship	Learning, validation, uncertain relationships

Full Mode Protocol

1. Inventory - List all bounded contexts with aggregates
2. Dependency Scan - Identify data flow and service calls
3. Pattern Assignment - Apply selection criteria systematically
4. CML Generation - Produce complete context map
5. Diagram Generation - Create visual representation
6. Review Output - Mark uncertain relationships for human review

Quick Mode Protocol

1. Context List - Enumerate known bounded contexts
2. Obvious Relationships - Map clear upstream/downstream pairs
3. Basic CML - Generate minimal context map
4. Skip Ambiguous - Flag uncertain relationships for later

Guided Mode Protocol

1. Present Context Pair - Show two contexts to user
2. Ask Relationship - "Do these contexts interact?"
3. Determine Direction - "Which provides data/services?"
4. Select Pattern - Present pattern options with explanations
5. Confirm - Verify user agrees with classification
6. Repeat - Continue for all context pairs

Output Artifacts

1. Context Mapper DSL (CML) File

/* Context Map: <DomainName>
 * Generated: <date>
 * Source: Event storming session
 */

ContextMap <DomainName>Map {
    contains <Context1>
    contains <Context2>
    // ... relationships
}

2. Mermaid Diagram

graph LR
    subgraph "Core Domain"
        A[Context1]
    end
    subgraph "Supporting"
        B[Context2]
    end
    A -->|pattern| B

3. Integration Strategy Report

## Integration Strategies

### <Context1> -> <Context2>
- **Pattern:** Customer/Supplier
- **Direction:** Context1 (upstream) supplies Context2 (downstream)
- **Rationale:** <why this pattern>
- **Implementation:** <technical approach>
- **Team Impact:** <organizational considerations>

4. Team Topology Suggestions

Based on context relationships, suggest team boundaries following Team Topologies patterns (Stream-aligned, Platform, Enabling, Complicated Subsystem).

For team topology guidance: See references/team-topologies.md

Integration with Event Storming

Input from Event Storming

Context mapping consumes:

• Bounded Contexts - Named domain boundaries with primary aggregates
• Domain Events - Events that cross context boundaries
• Commands - Operations that trigger cross-context communication
• Actors - Users/systems that interact with multiple contexts

Workflow Integration

Domain Storytelling
    ↓ (understand business flow)
Event Storming
    ↓ (discover bounded contexts)
Context Mapping ← YOU ARE HERE
    ↓ (define relationships)
Modular Architecture
    ↓ (implement structure)
Fitness Functions
    (enforce boundaries)

Cross-Context Event Identification

When mapping contexts, identify:

1. Events crossing boundaries - Indicate integration needs
2. Shared aggregates - Potential Shared Kernel candidates
3. Translation requirements - ACL candidates
4. API contracts - OHS/PL candidates

Integration Strategies

For each pattern, there's a recommended technical implementation:

Pattern	Implementation Strategy
Shared Kernel	Shared NuGet package, common project reference
Customer/Supplier	Internal API, MediatR notifications
Anti-Corruption Layer	Adapter pattern, translation service
Open Host Service	REST API, gRPC service
Published Language	OpenAPI spec, Protobuf definitions
Partnership	Shared event bus, bilateral contracts
Conformist	Direct model adoption, no translation
Separate Ways	No integration code needed

For detailed implementation guidance: See references/integration-strategies.md

Example Output

E-Commerce Domain Context Map

/* Context Map: E-Commerce Platform
 * Generated: 2025-01-15
 * Bounded Contexts from event storming session
 */

ContextMap ECommercePlatform {
    contains OrderContext
    contains InventoryContext
    contains PaymentContext
    contains ShippingContext
    contains CustomerContext

    /* Order consumes inventory availability
     * Inventory owns stock truth, Order queries it
     */
    OrderContext [D,C]<-[U,S] InventoryContext

    /* Payment isolates external gateway
     * Gateway has foreign model, needs translation
     */
    PaymentContext [D,ACL]<-[U,OHS,PL] ExternalPaymentGateway

    /* Order and Shipping co-evolve
     * Both teams collaborate on fulfillment flow
     */
    OrderContext [P]<->[P] ShippingContext

    /* Customer data shared
     * CustomerInfo value object used by multiple contexts
     */
    OrderContext [SK]<->[SK] CustomerContext
    ShippingContext [SK]<->[SK] CustomerContext
}

Honest Limitations

What This Skill Does Well

• Systematic pattern identification from bounded contexts
• CML syntax generation for Context Mapper tooling
• Integration strategy recommendations based on patterns
• Team topology alignment suggestions
• Mermaid/PlantUML diagram generation

What Requires Human Input

• Team dynamics - Actual organizational politics and relationships
• Business priorities - Which integrations matter most
• Legacy constraints - Existing systems that limit options
• Change appetite - Organizational readiness for restructuring
• Trade-off decisions - When multiple patterns could work

All outputs clearly distinguish recommendations from requirements and flag uncertain classifications for human review.

Related Skills

• event-storming - Discover bounded contexts (prerequisite)
• domain-storytelling - Understand business flow (optional prerequisite)
• modular-architecture - Implement module structure (next step)
• adr-management - Document integration decisions
• architecture-documentation - Generate architecture diagrams

References

• Pattern Catalog - All 8 patterns with examples
• CML Syntax - Context Mapper DSL reference
• Pattern Selection - Decision guide
• Integration Strategies - Technical implementation
• Team Topologies - Organizational alignment

Version History

• v1.0.0 (2025-12-22): Initial release - Context mapping patterns, CML output, multi-mode execution

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Last Updated: 2025-12-22 Model: claude-opus-4-5-20251101