Level-aware C4 semantic types

Use level-aware semantic types to describe the architectural responsibilities of systems, containers, and components in AAL.

AAL C4 v0.2 — Level-Aware Semantics
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Semantic Types Overview

AAL C4 v0.2 introduces a level-aware semantic taxonomy. Semantic types are explicitly associated with valid C4 structural levels — they are no longer a single flat global list.

When you select an element in the Inspector, the Semantic Type dropdown shows only valid semantics for that element's structural type, grouped by category and searchable.

84
System Semantics
112
Container Semantics
113
Component Semantics
Design Rule: A semantic type should represent architectural responsibility, not a product/vendor name. Use repository (architectural role), not springdata (technology). This makes the AAL taxonomy durable as technologies change.

System Semantics

System semantics describe what role a Software System plays in the wider technology landscape. They are valid only on Software System elements.

84 semantic types across 13 categories.

Enterprise / Business

application
Application

A general-purpose business application system.

Example
system BillingApp "Billing Application" application
platform
Platform

An integration or application platform.

Example
system IntegrationPlatform "Integration Platform" platform
portal
Portal

A web portal system providing access to multiple services.

Example
system CustomerPortal "Customer Portal" portal
crm
CRM

A Customer Relationship Management system.

Example
system Salesforce "Salesforce" external crm
erp
ERP

An Enterprise Resource Planning system.

Example
system ERP "Enterprise Resource Planning" external erp
billing
Billing

A billing and invoicing system.

Example
system BillingPlatform "Billing Platform" billing
payments
Payments

A payments processing system.

Example
system PaymentSystem "Payment System" payments
commerce
Commerce

An e-commerce or commerce platform.

Example
system CommercePlatform "Commerce Platform" commerce
policyadmin
Policy Admin

A policy administration system (insurance).

Example
system PolicyAdmin "Policy Administration System" external policyadmin
coresystem
Core System

A core business system (core banking, core insurance).

Example
system CoreBanking "Core Banking System" external coresystem
workflow
Workflow

A workflow or BPM system.

Example
system ServiceNow "ServiceNow" external workflow
cms
CMS

A content management system.

Example
system ContentSystem "Content Management" external cms
dms
DMS

A document management system.

Example
system DocSystem "Document Management" external dms
casemanagement
Case Management

A case management system.

Example
system CaseSystem "Case Management System" external casemanagement

Identity / Security

identity
Identity

An identity provider or IdP (Okta, Auth0, Azure AD).

Example
system Okta "Okta" external identity
security
Security

A security platform.

Example
system SecurityPlatform "Security Platform" external security
fraud
Fraud

A fraud detection platform.

Example
system FraudPlatform "Fraud Detection Platform" external fraud
iam
IAM

An Identity and Access Management system.

Example
system IAM "IAM System" external iam
pki
PKI

A Public Key Infrastructure system.

Example
system PKI "PKI System" external pki
siem
SIEM

A Security Information and Event Management system.

Example
system SecurityMonitoring "Enterprise SIEM" external siem
soc
SOC

A Security Operations Center platform.

Example
system SOC "Security Operations Center" external soc

Integration

integrationplatform
Integration Platform

An enterprise integration platform.

Example
system IntegrationPlatform "Enterprise Integration" external integrationplatform
apiplatform
API Platform

An enterprise API platform.

Example
system CommonAPI "Enterprise API Platform" external apiplatform
messagingplatform
Messaging Platform

An enterprise messaging platform.

Example
system MessagingPlatform "Enterprise Messaging" external messagingplatform
eventplatform
Event Platform

An enterprise event platform.

Example
system EventPlatform "Enterprise Event Platform" external eventplatform
filetransferplatform
File Transfer Platform

A managed file transfer platform.

Example
system MFTPlatform "Managed File Transfer Platform" external filetransferplatform
partnerplatform
Partner Platform

A partner integration platform.

Example
system PartnerPlatform "Partner Integration Platform" external partnerplatform

Data

dataplatform
Data Platform

An enterprise data platform.

Example
system EnterpriseData "Enterprise Data Platform" dataplatform
analytics
Analytics

An analytics platform.

Example
system AnalyticsPlatform "Analytics Platform" analytics
datawarehouse
Data Warehouse

An enterprise data warehouse.

Example
system DataWarehouse "Enterprise Data Warehouse" external datawarehouse
datalake
Data Lake

An enterprise data lake.

Example
system EnterpriseLake "Enterprise Data Lake" external datalake
lakehouse
Lakehouse

An enterprise lakehouse.

Example
system EnterpriseLakehouse "Enterprise Lakehouse" external lakehouse
mdm
MDM

A Master Data Management platform.

Example
system Customer360 "Customer 360" external mdm
searchplatform
Search Platform

An enterprise search platform.

Example
system SearchPlatform "Enterprise Search" external searchplatform
reporting
Reporting

A reporting and BI platform.

Example
system ReportingPlatform "Reporting Platform" external reporting
datacontract
Data Contract Platform

A data contract platform enforcing schema and quality agreements between producers and consumers.

Example
system DataContracts "Data Contract Platform" datacontract
semanticlayer
Semantic / Metrics Layer

A semantic/metrics layer providing governed, reusable business metrics.

Example
system SemanticLayer "Semantic Metrics Layer" semanticlayer
datamesh
Data Mesh

A data mesh platform enabling domain-oriented, decentralized data ownership.

Example
system DataMesh "Data Mesh Platform" datamesh
reversetl
Reverse ETL

A reverse ETL platform syncing warehouse data back into operational tools.

Example
system ReverseETL "Reverse ETL Platform" reversetl

AI

aiplatform
AI Platform

An enterprise AI platform.

Example
system EnterpriseAI "Enterprise AI Platform" aiplatform
modelplatform
Model Platform

An AI model serving platform.

Example
system OpenAIPlatform "AI Model Platform" external modelplatform
agentplatform
Agent Platform

An AI agent platform.

Example
system AgentPlatform "Enterprise Agent Platform" agentplatform
mlplatform
ML Platform

A machine learning platform.

Example
system MLPlatform "ML Platform" external mlplatform
knowledgeplatform
Knowledge Platform

A knowledge management platform for AI.

Example
system KnowledgePlatform "Knowledge Platform" external knowledgeplatform
evalplatform
AI Eval Platform

A platform for evaluating, benchmarking, and regression-testing AI models and agents.

Example
system EvalPlatform "AI Evaluation Platform" evalplatform
ragplatform
RAG Platform

A retrieval-augmented generation platform combining ingestion, retrieval, and generation.

Example
system RAGPlatform "Enterprise RAG Platform" ragplatform
agentorchestration
Agent Orchestration

A multi-agent orchestration platform that coordinates autonomous agents and workflows.

Example
system AgentOrchestrator "Agent Orchestration Platform" agentorchestration
modelregistry
Model Registry

A model registry and catalog for versioning, lineage, and governance of AI models.

Example
system ModelRegistry "Model Registry" modelregistry
voiceai
Voice AI

A voice AI platform (speech-to-text, text-to-speech, voice agents).

Example
system VoiceAI "Voice AI Platform" voiceai
multimodalai
Multimodal AI

A multimodal AI platform handling text, image, audio, and video.

Example
system MultimodalAI "Multimodal AI Platform" multimodalai
a2aplatform
A2A / Agent Network

An agent-to-agent (A2A) network platform for inter-agent discovery and collaboration.

Example
system A2ANetwork "Agent-to-Agent Network" a2aplatform

Observability / Operations

observability
Observability

An observability platform (Datadog, New Relic).

Example
system Datadog "Observability Platform" external observability
monitoring
Monitoring

A monitoring platform.

Example
system MonitoringPlatform "Monitoring Platform" external monitoring
logging
Logging

A log management platform.

Example
system LoggingPlatform "Log Management" external logging
itsm
ITSM

An IT Service Management platform.

Example
system ServiceManagement "IT Service Management" external itsm
devops
DevOps

A DevOps platform.

Example
system DevOpsPlatform "DevOps Platform" external devops
cicd
CI/CD

A CI/CD platform.

Example
system CICDPlatform "Enterprise CI/CD Platform" cicd

Infrastructure / Cloud

cloudplatform
Cloud Platform

A cloud platform (AWS, Azure, GCP).

Example
system AWSPlatform "AWS Platform" cloudplatform
hostingplatform
Hosting Platform

A hosting platform.

Example
system HostingPlatform "Hosting Platform" external hostingplatform
containerplatform
Container Platform

A container orchestration platform (Kubernetes, ECS).

Example
system KubernetesPlatform "Container Platform" containerplatform
serverlessplatform
Serverless Platform

A serverless compute platform.

Example
system ServerlessPlatform "Serverless Platform" external serverlessplatform
networkplatform
Network Platform

A networking platform.

Example
system NetworkPlatform "Network Platform" external networkplatform
edgeplatform
Edge Platform

An edge computing platform.

Example
system EdgePlatform "Edge Platform" external edgeplatform

Legacy

legacy
Legacy

A legacy system (informational, not judgmental).

Example
system Ingenium "Ingenium PAS" external legacy
mainframe
Mainframe

A mainframe system (IBM z/OS, AS/400).

Example
system Mainframe "Core Mainframe" external mainframe
host
Host

A host system.

Example
system HostSystem "Host System" external host
monolith
Monolith

A monolithic system.

Example
system Monolith "Monolithic System" external monolith

SaaS / External Provider

saas
SaaS

An external SaaS platform (Salesforce, ServiceNow, Workday).

Example
system Salesforce "Salesforce" external saas
thirdparty
Third Party

A third-party service.

Example
system ThirdParty "Third Party Service" external thirdparty
partner
Partner

A partner system.

Example
system PartnerSystem "Partner System" external partner
government
Government

A government system.

Example
system GovernmentSystem "Government System" external government
bank
Bank

An external banking system.

Example
system ExternalBank "Partner Bank" external bank
paymentprovider
Payment Provider

A payment provider.

Example
system Stripe "Stripe" external paymentprovider
notificationprovider
Notification Provider

A notification provider.

Example
system Infobip "Infobip" external notificationprovider
identityprovider
Identity Provider

An identity provider service.

Example
system OktaIdP "Okta Identity Provider" external identityprovider

Platform Engineering

developerportal
Developer Portal / IDP

An internal developer platform and portal (Backstage-like) with golden paths and templates.

Example
system DeveloperPortal "Internal Developer Portal" developerportal
platformengineering
Platform Engineering

A platform engineering system providing shared capabilities to product teams.

Example
system PlatformEngineering "Platform Engineering" platformengineering

Real-Time / Streaming

realtimeplatform
Real-Time Platform

A real-time data and streaming platform (Kafka, Flink, Pulsar).

Example
system RealTimePlatform "Real-Time Platform" realtimeplatform

FinOps / Sustainability

finops
FinOps

A FinOps platform for cloud cost visibility, optimization, and unit economics.

Example
system FinOpsPlatform "FinOps Platform" finops
greenops
GreenOps / Sustainability

A sustainability platform tracking carbon footprint and energy efficiency.

Example
system GreenOps "GreenOps Platform" greenops

Supply Chain Security

zerotrust
Zero Trust

A zero-trust security platform enforcing identity-based access.

Example
system ZeroTrust "Zero Trust Platform" zerotrust
supplychainsecurity
Supply Chain Security

A software supply chain security platform (SBOM, SLSA, artifact signing).

Example
system SupplyChainSecurity "Supply Chain Security" supplychainsecurity
posturemanagement
Posture Management

A cloud security posture management (CSPM/CWPP) platform.

Example
system PostureManagement "Cloud Posture Management" posturemanagement
apisecurity
API Security

An API security platform for discovery, testing, and runtime protection.

Example
system APISecurity "API Security Platform" apisecurity
Invalid
Example
component LoginController "Login Controller" controller

"controller" is a Component semantic type, not a System semantic type. System semantics include crm, identity, coresystem, dataplatform, aiplatform, etc.

Container Semantics

Container semantics describe deployable/executable/runtime responsibilities inside a Software System. They are valid only on Container elements.

112 semantic types across 13 categories.

Experience & Channels

mobile
Mobile

A native mobile application (iOS, Android, React Native).

Example
container MobileApp "Mobile App" mobile
web
Web

A web application or browser-based interface.

Example
container WebPortal "Web Portal" web
spa
SPA

A single-page application.

Example
container AdminSPA "Administration UI" spa
desktop
Desktop

A desktop application (Windows, macOS, Linux).

Example
container TradingTerminal "Trading Desktop" desktop
device
Device

A physical device endpoint (POS terminal, kiosk, ATM).

Example
container PaymentTerminal "Payment Terminal" device
iot
IoT

An IoT gateway or edge device.

Example
container SensorGateway "IoT Gateway" iot
cli
CLI

A command-line interface tool.

Example
container OperationsCLI "Operations CLI" cli

Application & Compute

api
API

An application programming interface (REST, GraphQL, gRPC).

Example
container CustomerAPI "Customer API" api
bff
BFF

A Backend for Frontend — a specialized adapter between frontends and backend services.

Example
container BFF "Backend for Frontend" bff
service
Service

A background service or microservice.

Example
container NotificationService "Notification Service" service
microservice
Microservice

A microservice.

Example
container OrderMicroservice "Order Microservice" microservice
worker
Worker

A background-processing worker that consumes messages or jobs.

Example
container NotificationWorker "Notification Worker" worker
batch
Batch

A scheduled or on-demand batch processing workload.

Example
container ReconciliationBatch "Reconciliation Batch" batch
function
Function

A serverless function (AWS Lambda, Azure Functions, Cloud Run).

Example
container TokenFunction "Token Function" function
scheduler
Scheduler

A job scheduler or orchestration engine.

Example
container JobScheduler "Job Scheduler" scheduler
job
Job

A scheduled job.

Example
container CleanupJob "Cleanup Job" job
daemon
Daemon

A daemon process.

Example
container BackgroundDaemon "Background Daemon" daemon
processor
Processor

A data processor.

Example
container DataProcessor "Data Processor" processor
orchestrator
Orchestrator

An orchestration service.

Example
container WorkflowOrchestrator "Workflow Orchestrator" orchestrator

Integration & Messaging

gateway
Gateway

An API gateway that routes and transforms requests.

Example
container Gateway "API Gateway" gateway
apigateway
API Gateway

A dedicated API gateway.

Example
container APIGateway "API Gateway" apigateway
queue
Queue

A message queue for asynchronous point-to-point communication.

Example
container CommandQueue "Command Queue" queue
broker
Broker

A message broker that routes messages between publishers and subscribers.

Example
container MessageBroker "Message Broker" broker
eventbus
Event Bus

An enterprise event bus for publish/subscribe event distribution.

Example
container EventBus "Enterprise Event Bus" eventbus
stream
Stream

A data streaming platform (Kafka Streams, Kinesis, Pulsar).

Example
container KafkaStream "Transaction Stream" stream
topic
Topic

A messaging topic.

Example
container OrderTopic "Order Topic" topic
pubsub
Pub/Sub

A publish/subscribe channel.

Example
container NotificationPubSub "Notification Pub/Sub" pubsub
filetransfer
File Transfer

A managed file transfer service (MFT, SFTP gateway).

Example
container MFT "Managed File Transfer" filetransfer
adapter
Adapter

An integration adapter.

Example
container LegacyAdapter "Legacy Adapter" adapter
connector
Connector

An integration connector.

Example
container CRMConnector "CRM Connector" connector
proxy
Proxy

A reverse proxy.

Example
container ReverseProxy "Reverse Proxy" proxy

Data

database
Database

A relational or NoSQL database.

Example
container ClientDB "Client Database" database
relationaldb
Relational DB

A relational database (PostgreSQL, MySQL, Oracle).

Example
container CustomerDB "Customer Database" relationaldb
nosqldb
NoSQL DB

A NoSQL database (MongoDB, DynamoDB, Cassandra).

Example
container ProfileStore "Profile Store" nosqldb
cache
Cache

An in-memory cache (Redis, Memcached).

Example
container SessionCache "Session Cache" cache
objectstore
Object Storage

An object/blob storage service (S3, Azure Blob).

Example
container Documents "Object Storage" objectstore
filestore
File Store

A file storage service.

Example
container FileStore "File Store" filestore
datalake
Data Lake

A raw data lake for unstructured and semi-structured data.

Example
container EnterpriseLake "Enterprise Data Lake" datalake
warehouse
Warehouse

A structured analytics data warehouse (Snowflake, BigQuery).

Example
container AnalyticsWarehouse "Analytics Warehouse" warehouse
lakehouse
Lakehouse

A unified lakehouse combining lake and warehouse semantics.

Example
container DataLakehouse "Enterprise Lakehouse" lakehouse
search
Search Index

A search and indexing engine (Elasticsearch, OpenSearch).

Example
container SearchIndex "Search Index" search
vectorstore
Vector Store

A vector embedding store for similarity search (Pinecone, Weaviate).

Example
container KnowledgeVectors "Knowledge Vector Store" vectorstore
graphdb
Graph Database

A graph database (Neo4j, Amazon Neptune).

Example
container RelationshipGraph "Graph Database" graphdb
timeseriesdb
Time-Series DB

A time-series database (InfluxDB, TimescaleDB, Timestream).

Example
container MetricsStore "Metrics Store" timeseriesdb
featurestore
Feature Store

An ML feature store for serving and training features.

Example
container MLFeatures "Feature Store" featurestore
metadatarepository
Metadata Repository

A metadata repository.

Example
container MetadataRepo "Metadata Repository" metadatarepository
realtimedata
Real-Time Data

A real-time data store or materialized view for low-latency serving.

Example
container RealTimeData "Real-Time Data Store" realtimedata
metricsservice
Metrics / Semantic Layer

A governed metrics and semantic layer service (dbt metrics, Cube).

Example
container MetricsService "Metrics Service" metricsservice
datacontract
Data Contract

A data contract service enforcing producer/consumer schema agreements.

Example
container DataContract "Data Contract Service" datacontract
reversetl
Reverse ETL

A reverse ETL service syncing warehouse data to operational systems.

Example
container ReverseETL "Reverse ETL Service" reversetl

Security / Identity

identity
Identity

An identity service or IdP.

Example
container IdentityService "Identity Service" identity
authservice
Auth Service

An authentication service.

Example
container AuthService "Authentication Service" authservice
authorization
Authorization

An authorization service.

Example
container AuthZ "Authorization Service" authorization
waf
WAF

A web application firewall.

Example
container WebFirewall "Web Application Firewall" waf
firewall
Firewall

A network firewall.

Example
container NetworkFirewall "Network Firewall" firewall
secrets
Secrets Vault

A secrets management vault (HashiCorp Vault, AWS Secrets Manager).

Example
container SecretsVault "Secrets Vault" secrets
kms
KMS

A key management service for encryption keys.

Example
container KeyManagement "Key Management Service" kms
tokenservice
Token Service

A token issuance and validation service.

Example
container TokenService "Token Service" tokenservice
certificate
Certificate

A certificate management service.

Example
container CertManager "Certificate Manager" certificate
zerotrustgateway
Zero Trust Gateway

A zero-trust access gateway enforcing identity and context per request.

Example
container ZeroTrustGateway "Zero Trust Gateway" zerotrustgateway
sbom
SBOM Service

A software bill of materials generation and scanning service.

Example
container SBOMService "SBOM Service" sbom
dlp
DLP Service

A data loss prevention service for sensitive data classification and blocking.

Example
container DLPService "DLP Service" dlp
posture
Posture Management

A cloud security posture management service (CSPM/CWPP).

Example
container PostureService "Posture Management" posture

Platform

platform
Platform

A platform service.

Example
container AppPlatform "Application Platform" platform
runtime
Runtime

An application runtime.

Example
container Runtime "Application Runtime" runtime
containerplatform
Container Platform

A container orchestration platform (Kubernetes, ECS).

Example
container RuntimePlatform "Container Platform" containerplatform
serverless
Serverless

A serverless compute platform (Lambda, Cloud Run).

Example
container ServerlessBackend "Serverless Backend" serverless
cdn
CDN

A content delivery network (CloudFront, Cloudflare).

Example
container ContentDelivery "Content Delivery Network" cdn
loadbalancer
Load Balancer

A load balancer or traffic distributor.

Example
container ApplicationLB "Application Load Balancer" loadbalancer
reverseproxy
Reverse Proxy

A reverse proxy.

Example
container ReverseProxy "Reverse Proxy" reverseproxy
servicemesh
Service Mesh

A service mesh (Istio, Linkerd).

Example
container ServiceMesh "Service Mesh" servicemesh

AI / ML

ai
AI Service

A generative AI service or platform.

Example
container GenAIService "Generative AI Service" ai
model
Model

A foundation or language model serving endpoint.

Example
container FoundationModel "Language Model" model
agent
Agent

An AI agent runtime or orchestration service.

Example
container AgentRuntime "AI Agent Runtime" agent
mcpserver
MCP Server

A Model Context Protocol tool server.

Example
container MCPServer "MCP Server" mcpserver
embedding
Embedding

An embedding generation service for vector representations.

Example
container EmbeddingService "Embedding Service" embedding
guardrail
Guardrail

An AI guardrail, safety, or content-filtering service.

Example
container AIGuardrail "AI Guardrail Service" guardrail
promptservice
Prompt Service

A prompt management and optimization service.

Example
container PromptService "Prompt Service" promptservice
modelgateway
Model Gateway

A model gateway that routes and load-balances LLM requests.

Example
container ModelGateway "Model Gateway" modelgateway
inference
Inference

A model inference service.

Example
container InferenceService "Inference Service" inference
training
Training

A model training service.

Example
container TrainingService "Training Service" training
rag
RAG Pipeline

A retrieval-augmented generation pipeline (ingest, chunk, embed, retrieve, generate).

Example
container RAGPipeline "RAG Pipeline" rag
toolregistry
Tool Registry

A registry of tools/functions callable by AI agents (MCP tools, function calling).

Example
container ToolRegistry "Tool Registry" toolregistry
eval
Eval Service

An evaluation service for AI quality, regression, and benchmarking.

Example
container EvalService "AI Eval Service" eval
finetuning
Fine-Tuning

A model fine-tuning and adaptation service (LoRA, instruction tuning).

Example
container FineTuning "Fine-Tuning Service" finetuning
voice
Voice / Speech

A speech and voice service (STT, TTS, voice agents).

Example
container VoiceService "Voice Service" voice
multimodal
Multimodal

A multimodal service processing text, image, audio, and video.

Example
container MultimodalService "Multimodal Service" multimodal
agentmemory
Agent Memory

A persistent memory and context store for AI agents (short/long-term memory).

Example
container AgentMemory "Agent Memory Store" agentmemory
chunking
Chunking / Ingestion

A document chunking and ingestion service for RAG pipelines.

Example
container ChunkingService "Chunking & Ingestion" chunking
a2aserver
A2A Server

An agent-to-agent (A2A) server exposing an agent for inter-agent collaboration.

Example
container A2AServer "A2A Server" a2aserver
agentcoordinator
Agent Coordinator

A multi-agent coordinator that routes, delegates, and supervises agents.

Example
container AgentCoordinator "Multi-Agent Coordinator" agentcoordinator

Observability / Ops

observability
Observability

A combined observability platform.

Example
container ObservabilityStack "Observability Stack" observability
monitoring
Monitoring

A metrics collection and monitoring service.

Example
container MetricsCollector "Metrics Collector" monitoring
logging
Logging

A log aggregation and pipeline service.

Example
container LogPipeline "Log Pipeline" logging
tracing
Tracing

A distributed tracing collector (Jaeger, Zipkin, OTel).

Example
container TraceCollector "Trace Collector" tracing
metrics
Metrics

A metrics collection service.

Example
container MetricsService "Metrics Service" metrics
alerting
Alerting

An alerting service.

Example
container AlertingService "Alerting Service" alerting
healthcheck
Health Check

A health check service.

Example
container HealthCheck "Health Check Service" healthcheck

Legacy

legacy
Legacy

A legacy application.

Example
container LegacyApp "Legacy Application" legacy
monolith
Monolith

A monolithic application.

Example
container MonolithApp "Monolithic Application" monolith
mainframeapp
Mainframe App

A mainframe application.

Example
container MainframeApp "Mainframe Application" mainframeapp
batchlegacy
Batch Legacy

A legacy batch process.

Example
container LegacyBatch "Legacy Batch Process" batchlegacy

Platform Engineering

idp
Developer Portal

An internal developer portal with service catalog and golden paths.

Example
container DevPortal "Developer Portal" idp
goldenpath
Golden Path / Template

A golden-path template service providing scaffolding and standardized workflows.

Example
container GoldenPath "Golden Path Template" goldenpath

Real-Time / Streaming

realtime
Real-Time Service

A real-time service over persistent connections (WebSocket, SSE, WebRTC).

Example
container RealTimeService "Real-Time Service" realtime
websocket
WebSocket

A WebSocket service for bidirectional, low-latency communication.

Example
container WebSocketService "WebSocket Service" websocket
sse
SSE / Server-Sent Events

A server-sent events streaming endpoint.

Example
container SSEService "SSE Service" sse

FinOps / Sustainability

costoptimizer
Cost Optimizer

A cloud cost optimization and rightsizing service.

Example
container CostOptimizer "Cost Optimizer" costoptimizer
carbontracker
Carbon Tracker

A carbon and energy-efficiency tracking service.

Example
container CarbonTracker "Carbon Tracker" carbontracker

Edge / WebAssembly

wasm
WASM Runtime

A WebAssembly runtime for portable, sandboxed compute.

Example
container WASMRuntime "WASM Runtime" wasm
edgefunction
Edge Function

An edge compute function running close to users (Cloudflare Workers, Lambda@Edge).

Example
container EdgeFunction "Edge Function" edgefunction
wasmcomponent
WASM Component

A composable WebAssembly component (component model).

Example
container WASMComponent "WASM Component" wasmcomponent
Invalid
Example
container CRM "CRM" crm

"crm" is a System semantic type (unless explicitly configured as valid for Containers). Use Container semantics like api, web, database, eventbus, etc.

Component Semantics

Component semantics describe logical architectural responsibility inside a Container. They are valid only on Component elements. Components should represent architectural responsibilities, not individual implementation classes.

113 semantic types across 15 categories.

Entry / Interface

controller
Controller

An MVC or web controller that receives HTTP requests and delegates to services.

Example
component PolicyController "Policy Controller" controller
endpoint
Endpoint

An API endpoint handler.

Example
component UserEndpoint "User Endpoint" endpoint
handler
Handler

A request or event handler.

Example
component RegistrationHandler "Registration Handler" handler
resolver
Resolver

A GraphQL resolver.

Example
component UserResolver "User Resolver" resolver
listener
Listener

An event or message listener.

Example
component OrderListener "Order Listener" listener
receiver
Receiver

A message receiver.

Example
component EmailReceiver "Email Receiver" receiver
webhook
Webhook

A webhook handler that receives external callbacks.

Example
component PaymentWebhook "Payment Webhook Handler" webhook
commandhandler
Command Handler

A CQRS command handler.

Example
component RegistrationHandler "Registration Command Handler" commandhandler
queryhandler
Query Handler

A CQRS query handler.

Example
component CustomerQueryHandler "Customer Query Handler" queryhandler

Application / Business Logic

service
Service

A business service component.

Example
component AuthService "Auth Service" service
applicationservice
Application Service

An application service that orchestrates use cases.

Example
component PolicyService "Policy Service" applicationservice
domainservice
Domain Service

A domain service that encapsulates core domain logic.

Example
component CustomerDomain "Customer Domain Service" domainservice
domain
Domain

A domain module.

Example
component CustomerDomain "Customer Domain" domain
usecase
Use Case

A use case component.

Example
component RegisterUser "Register User Use Case" usecase
orchestrator
Orchestrator

An orchestrator that coordinates multi-step workflows.

Example
component RegistrationOrchestrator "Registration Orchestrator" orchestrator
workflow
Workflow

A workflow component.

Example
component OnboardingWorkflow "Onboarding Workflow" workflow
manager
Manager

A manager component that coordinates lifecycle operations.

Example
component SessionManager "Session Manager" manager
coordinator
Coordinator

A coordinator component.

Example
component SagaCoordinator "Saga Coordinator" coordinator
facade
Facade

A facade that simplifies access to complex subsystems.

Example
component CustomerFacade "Customer Facade" facade

Data Access

repository
Repository

A repository pattern abstraction over persistence or data access.

Example
component PolicyRepository "Policy Repository" repository
dao
DAO

A Data Access Object.

Example
component CustomerDAO "Customer Data Access Object" dao
dataaccess
Data Access

A data access component.

Example
component CustomerDataAccess "Customer Data Access" dataaccess
mapper
Mapper

A data mapper that translates between models.

Example
component PolicyMapper "Policy Mapper" mapper
orm
ORM

An Object-Relational Mapping component.

Example
component CustomerORM "Customer ORM" orm
query
Query

A query component.

Example
component CustomerQuery "Customer Query" query
projection
Projection

A read projection for CQRS read models.

Example
component CustomerProjection "Customer Projection" projection
datacontract
Data Contract

A data contract component enforcing schema agreements.

Example
component DataContract "Data Contract" datacontract
metric
Metric Definition

A governed metric definition component.

Example
component MetricDefinition "Metric Definition" metric
reversetl
Reverse ETL Sync

A reverse ETL sync component pushing warehouse data to ops tools.

Example
component ReverseETLSync "Reverse ETL Sync" reversetl

Integration

adapter
Adapter

An integration adapter that bridges external systems.

Example
component IngeniumAdapter "Ingenium Adapter" adapter
connector
Connector

An integration connector.

Example
component CRMConnector "CRM Connector" connector
client
Client

An external API client.

Example
component OktaClient "Okta Client" client
gateway
Gateway

An integration gateway component.

Example
component PaymentGateway "Payment Gateway" gateway
proxy
Proxy

A proxy component.

Example
component APIProxy "API Proxy" proxy
integration
Integration

A general integration component.

Example
component ExternalIntegration "External Integration" integration
publisher
Publisher

An event publisher.

Example
component PolicyEventPublisher "Policy Event Publisher" publisher
producer
Producer

A message producer.

Example
component OrderProducer "Order Producer" producer
consumer
Consumer

A message consumer.

Example
component NotificationConsumer "Notification Consumer" consumer
subscriber
Subscriber

A message subscriber.

Example
component EventSubscriber "Event Subscriber" subscriber

Security

authenticator
Authenticator

An authentication component.

Example
component UserAuthenticator "User Authenticator" authenticator
authorizer
Authorizer

An authorization component.

Example
component AccessAuthorizer "Access Authorizer" authorizer
validator
Validator

A validation component.

Example
component PayloadValidator "Payload Validator" validator
tokenvalidator
Token Validator

A token validation component.

Example
component TokenValidator "Token Validator" tokenvalidator
permission
Permission

A permission component.

Example
component PermissionCheck "Permission Check" permission
policy
Policy

An authorization policy component.

Example
component AuthorizationPolicy "Authorization Policy" policy
filter
Filter

A security filter component.

Example
component SecurityFilter "Security Filter" filter
interceptor
Interceptor

An interceptor component.

Example
component AuthInterceptor "Auth Interceptor" interceptor
policyengine
Policy Engine

An authorization policy engine (OPA, Cedar) evaluating rules.

Example
component PolicyEngine "Policy Engine" policyengine
sbom
SBOM Generator

A software bill of materials generator component.

Example
component SBOMGenerator "SBOM Generator" sbom
dlp
DLP Filter

A data loss prevention filter component.

Example
component DLPFilter "DLP Filter" dlp
posturecheck
Posture Check

A cloud security posture check component.

Example
component PostureCheck "Posture Check" posturecheck
secretsaccessor
Secrets Accessor

A component that accesses secrets from a vault.

Example
component SecretsAccessor "Secrets Accessor" secretsaccessor

Processing / Transformation

processor
Processor

A data processor.

Example
component EventProcessor "Event Processor" processor
transformer
Transformer

A data transformer.

Example
component DataTransformer "Data Transformer" transformer
parser
Parser

A parser component.

Example
component PayloadParser "Payload Parser" parser
serializer
Serializer

A serializer.

Example
component JsonSerializer "JSON Serializer" serializer
deserializer
Deserializer

A deserializer.

Example
component JsonDeserializer "JSON Deserializer" deserializer
enricher
Enricher

A data enricher that adds supplementary data.

Example
component ClientEnricher "Client Data Enricher" enricher
aggregator
Aggregator

A data aggregator.

Example
component MetricsAggregator "Metrics Aggregator" aggregator
normalizer
Normalizer

A data normalizer.

Example
component DataNormalizer "Data Normalizer" normalizer
converter
Converter

A data converter.

Example
component UnitConverter "Unit Converter" converter

Rules / Decisioning

rule
Rule

A business rule.

Example
component EligibilityRule "Eligibility Rule" rule
rulesengine
Rules Engine

A rules engine.

Example
component EligibilityRules "Eligibility Rules Engine" rulesengine
decision
Decision

A decision engine.

Example
component DecisionEngine "Decision Engine" decision
evaluator
Evaluator

A rule evaluator.

Example
component PolicyEvaluator "Policy Evaluator" evaluator
scorer
Scorer

A scoring component.

Example
component FraudScorer "Fraud Scorer" scorer

Cache / State

cacheclient
Cache Client

A cache client component.

Example
component CacheClient "Cache Client" cacheclient
sessionmanager
Session Manager

A session manager component.

Example
component SessionManager "Session Manager" sessionmanager
statemanager
State Manager

A state manager component.

Example
component StateManager "State Manager" statemanager
store
Store

A state store component.

Example
component StateStore "State Store" store

AI

agent
Agent

An AI agent component.

Example
component AgentPlanner "Agent Planner" agent
planner
Planner

An AI planner component.

Example
component AgentPlanner "Agent Planner" planner
tool
Tool

An AI tool component.

Example
component SearchTool "Search Tool" tool
tooladapter
Tool Adapter

An AI tool adapter component.

Example
component CRMTool "CRM Tool Adapter" tooladapter
prompt
Prompt

A prompt component.

Example
component SystemPrompt "System Prompt" prompt
promptbuilder
Prompt Builder

A prompt builder component.

Example
component PromptBuilder "Prompt Builder" promptbuilder
modelclient
Model Client

A model client component.

Example
component ModelClient "Model Client" modelclient
embeddingclient
Embedding Client

An embedding client component.

Example
component EmbeddingClient "Embedding Client" embeddingclient
retriever
Retriever

A knowledge retriever component.

Example
component KnowledgeRetriever "Knowledge Retriever" retriever
reranker
Reranker

A result reranker component.

Example
component ResultReranker "Result Reranker" reranker
guardrail
Guardrail

An AI guardrail component.

Example
component AIGuardrail "AI Guardrail" guardrail
memory
Memory

An AI memory component.

Example
component AgentMemory "Agent Memory" memory
contextbuilder
Context Builder

A context builder component.

Example
component ContextBuilder "Context Builder" contextbuilder
aieval
AI Evaluator

An AI evaluation component that runs quality and regression checks.

Example
component AIEvaluator "AI Evaluator" aieval
rag
RAG

A retrieval-augmented generation component.

Example
component RAGComponent "RAG Component" rag
chunker
Chunker

A document chunking and ingestion component for embeddings.

Example
component DocumentChunker "Document Chunker" chunker
toolregistry
Tool Registry

A registry of callable AI tools and functions.

Example
component ToolRegistry "Tool Registry" toolregistry
functioncaller
Function / Tool Caller

A component that invokes tools/functions on behalf of an agent (function calling).

Example
component FunctionCaller "Function Caller" functioncaller
agentcoordinator
Agent Coordinator

A multi-agent coordinator that routes and supervises agent execution.

Example
component AgentCoordinator "Agent Coordinator" agentcoordinator
voice
Voice Component

A speech/voice processing component (STT, TTS).

Example
component VoiceComponent "Voice Component" voice
multimodal
Multimodal Component

A multimodal component handling text, image, audio, or video.

Example
component MultimodalComponent "Multimodal Component" multimodal
mcpclient
MCP Client

A Model Context Protocol client that calls MCP tool servers.

Example
component MCPClient "MCP Client" mcpclient
a2aclient
A2A Client

An agent-to-agent client that collaborates with other agents.

Example
component A2AClient "A2A Client" a2aclient
finetuner
Fine-Tuner

A model fine-tuning and adaptation component.

Example
component FineTuner "Fine-Tuner" finetuner

Observability

logger
Logger

A logger component.

Example
component AuditLogger "Audit Logger" logger
tracer
Tracer

A tracer component.

Example
component RequestTracer "Request Tracer" tracer
metricscollector
Metrics Collector

A metrics collector component.

Example
component MetricsCollector "Metrics Collector" metricscollector
telemetry
Telemetry

A telemetry component.

Example
component TelemetryCollector "Telemetry Collector" telemetry
audit
Audit

An audit component.

Example
component AuditLogger "Audit Logger" audit

Scheduling / Background

scheduler
Scheduler

A scheduler component.

Example
component TaskScheduler "Task Scheduler" scheduler
job
Job

A job component.

Example
component CleanupJob "Cleanup Job" job
worker
Worker

A worker component.

Example
component BackgroundWorker "Background Worker" worker
task
Task

A task component.

Example
component BackgroundTask "Background Task" task

Platform Engineering

goldenpath
Golden Path

A golden-path component providing standardized workflows.

Example
component GoldenPath "Golden Path" goldenpath
scaffold
Scaffolder

A scaffolding component that generates service templates.

Example
component Scaffolder "Scaffolder" scaffold
plugin
Plugin

A platform plugin extending the developer portal.

Example
component PortalPlugin "Portal Plugin" plugin

Real-Time / Streaming

realtime
Real-Time Handler

A real-time handler over persistent connections.

Example
component RealTimeHandler "Real-Time Handler" realtime
websocket
WebSocket Handler

A WebSocket handler component.

Example
component WebSocketHandler "WebSocket Handler" websocket
sse
SSE Handler

A server-sent events handler component.

Example
component SSEHandler "SSE Handler" sse

FinOps / Sustainability

costanalyzer
Cost Analyzer

A cost analysis and unit-economics component.

Example
component CostAnalyzer "Cost Analyzer" costanalyzer
carbonreporter
Carbon Reporter

A carbon and energy reporting component.

Example
component CarbonReporter "Carbon Reporter" carbonreporter

Edge / WebAssembly

wasm
WASM Module

A WebAssembly module component.

Example
component WASMModule "WASM Module" wasm
edgehandler
Edge Handler

An edge compute handler running close to users.

Example
component EdgeHandler "Edge Handler" edgehandler
Invalid
Example
component DB "Database" database

"database" is a Container semantic type, not a Component semantic type. Use Component semantics like repository, dataaccess, store, etc.

Cross-Level Semantics

Some semantic types are valid at more than one C4 level. These are explicitly defined with allowedStructuralTypes rather than assumed to be globally valid.

platform
Platform
Valid at: system, container
workflow
Workflow
Valid at: system, component
identity
Identity
Valid at: system, container
datalake
Data Lake
Valid at: system, container
lakehouse
Lakehouse
Valid at: system, container
observability
Observability
Valid at: system, container
monitoring
Monitoring
Valid at: system, container
logging
Logging
Valid at: system, container
containerplatform
Container Platform
Valid at: system, container
legacy
Legacy
Valid at: system, container
monolith
Monolith
Valid at: system, container
datacontract
Data Contract Platform
Valid at: system, container, component
reversetl
Reverse ETL
Valid at: system, container, component
service
Service
Valid at: container, component
worker
Worker
Valid at: container, component
scheduler
Scheduler
Valid at: container, component
job
Job
Valid at: container, component
processor
Processor
Valid at: container, component
orchestrator
Orchestrator
Valid at: container, component
gateway
Gateway
Valid at: container, component
adapter
Adapter
Valid at: container, component
connector
Connector
Valid at: container, component
proxy
Proxy
Valid at: container, component
agent
Agent
Valid at: container, component
guardrail
Guardrail
Valid at: container, component
rag
RAG Pipeline
Valid at: container, component
toolregistry
Tool Registry
Valid at: container, component
voice
Voice / Speech
Valid at: container, component
multimodal
Multimodal
Valid at: container, component
agentcoordinator
Agent Coordinator
Valid at: container, component
goldenpath
Golden Path / Template
Valid at: container, component
realtime
Real-Time Service
Valid at: container, component
websocket
WebSocket
Valid at: container, component
sse
SSE / Server-Sent Events
Valid at: container, component
wasm
WASM Runtime
Valid at: container, component
sbom
SBOM Service
Valid at: container, component
dlp
DLP Service
Valid at: container, component

For example, identity is valid for both System (identity provider) and Container (identity service). agent is valid for both Container (AI agent runtime) and Component (AI agent component).