> For the complete documentation index, see [llms.txt](https://docs.atsign.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.atsign.com/atsign-ai-architect/atsign-ai-architect-overview/nodes-and-connections.md). # Nodes and Connections ## Node Palette These nodes map your workflow visually. Each one represents an actor in your app or agentic system.

Description	When to use	Example
Person People or stakeholders	You want to model people's actions, permissions, or decision points.	A person logging into an admin dashboard, approving a workflow, or sending a secure message.
AI Agent AI Agent	You want to model automated reasoning, decision-making, or actions performed by an AI system.	An AI agent triaging support tickets, summarizing documents, or autonomously executing a multi-step workflow
Entity Businesses, groups of people, etc.	You need access for companies, tenants, departments, identity domains.	A healthcare provider, an insurance company, or a tenant account applying its own access rules.
Thing Physical or digital objects/devices	You’re modelling hardware, IoT devices, sensors, servers, or edge components.	A smart meter sending readings, a kiosk receiving updates, or a server reporting health status.
Process Anything that processes, runs, or executes: an app, service, or workflow	You want to show business logic, transformations, or background tasks.	A data validation step, a policy enforcement engine, or a message-routing workflow.
API External systems or platform integrations	You’re integrating with third-party services or exposing functionality programmatically.	A payment processor API, mapping service, or internal microservice endpoint.
Other Custom node type for anything else	You need to include concepts like storage, policies, models, or abstract systems.	A policy store, encryption module, AI model, or logging system.

## Connection Types These define how the nodes communicate with each other.

Connection	Description	When to use	Example
Default	Unsure? Let the LLM decide.	You're unsure which communication pattern fits, or the interaction doesn't clearly map to a specific type.	The LLM infers the best pattern based on context and intent
Async Comms	Asynchronous, non-blocking communication where the sender does not wait for a response and the receiver does not need to be online. Uses `Get/Put` semantics. Read more here.	Really handy if you cannot guarantee both the sender/ receiver will be online at the same time.	A device uploads data that is processed later, or a message is delivered when the recipient comes online.
Sync Comms	Synchronous communication where the sender waits for an immediate response. Uses `Notification` (Read more here) semantics and/or `Get/Put` (Read more here) semantics.	You need real-time interaction or confirmation.	A user request that must return a result immediately, like fetching account details_.
Notifications	One-way signals used to alert or inform. Uses `Notification` semantics Read more here.	You need to notify without requiring a response.	Push notifications, system alerts, or status updates sent to users or services.
RPC	Structured request/response interactions between systems. Ideal for complex operations where the other party may not be online at the time of execution (especially useful for policy-driven workflows). Supported in the `SDK` semantics. Read more here.	You want function-like calls across services with clear inputs and outputs.	Calling a billing service to calculate charges or a policy engine to validate access.
Data Stream	Ideal for long-running processes (such as LLM generation) where completion time is uncertain and results may need to stream incrementally. Uses the `stream` (Read more here) semantics or `notifications` (Read more here) semantics.	You’re handling live, ongoing data rather than discrete messages	Telemetry feeds, sensor data, logs, or real-time analytics pipelines.
TCP	Low-level, persistent network connections that enable lower latency communication (e.g., NoPorts SSH, MCP servers). Uses `Noports_Core` (Read more here) semantics.	You need a fast end-to-end encrypted TCP connection with raw network speed.	A custom protocol, legacy integration, or long-lived secure connection.

RPC