What is Temporal Nexus?

Nexus lets different teams share Temporal workflows across team, namespace, region, and cloud boundaries — without exposing internal implementation details.

The core idea in one sentence:

Team A can call Team B's workflows like a typed API — with full durability, retries, and fault-tolerance built in — without needing access to Team B's namespace or knowing how their code works.

The Problem Nexus Solves

Without Nexus

Siloed Teams

Each team works in their own Temporal namespace. There's no clean way for the Payments team to trigger an action in the Fraud Detection team's workflow without tight coupling or shared credentials.

Teams either share namespaces (messy) or build fragile HTTP bridges (unreliable).

With Nexus

Modular & Safe

The Fraud Detection team publishes a Nexus Service with a clear contract. The Payments team calls it from their workflow like any other operation.

Nexus handles routing, retries, security, and observability automatically — across any boundary.

What It Looks Like

Team A — Payments
W
PaymentWorkflow
Caller Namespace
Calls fraud.v1/checkTransaction
Waits for result (sync or async)
Nexus Endpoint
Routes securely
Retries + Auth
Team B — Fraud Detection
S
Nexus Service: fraud.v1
Handler Namespace
W
FraudCheckWorkflow
Runs internally, result returned

Key Facts

Durability

Up to 60 Days

Async Nexus Operations can run for up to 60 days in Temporal Cloud. The caller workflow is suspended until the result arrives.

Reliability

At-Least-Once

Nexus Machinery retries failed operations automatically. Pair with workflow ID policies to get exactly-once semantics.

Security

Built-in Auth

mTLS encryption and namespace allowlists control who can call what. No API keys flying around in code.

Boundaries

Cross-Everything

Works across teams, namespaces, regions (AWS & GCP), and clouds — with the same developer experience everywhere.

The Four Building Blocks

Nexus has four key concepts. These four concepts are the foundation of everything in Nexus.

1

Nexus Endpoint

The address you publish and route through

Think of an Endpoint like a URL for your team's services. It's a named entry point registered in the Nexus Registry that routes requests to a specific namespace and task queue.

It's not a general HTTP proxy — it's specifically designed for Nexus, with built-in auth, retries, and observability.

Endpoint: fraud-detection-prod
Routes to: fraud-ns / fraud-task-queue
2

Nexus Service

The contract you publish for others to consume

A Service is a named collection of Nexus Operations — like an API interface. Multiple services can run in the same worker. Callers import the service definition to get type safety.

Example: fraud.v1 service exposes checkTransaction, flagUser, and getScore operations.

3

Nexus Operation

The individual action — sync or async

Synchronous operations complete in under 10 seconds. The result comes back in the same HTTP round-trip. Great for quick lookups, scoring, or validations.

Caller → [Nexus RPC] → Handler → result → Caller
Duration: milliseconds to <10 seconds

Asynchronous operations start a Workflow and return an operation token. The caller workflow is suspended. When the handler workflow completes, a callback delivers the result.

Caller → [start] → Handler starts Workflow → [operation token]
...time passes (up to 60 days)...
Handler Workflow completes → [callback] → Caller resumes
4

Nexus Registry

The directory of all Endpoints in your account

Scoped to your Temporal Cloud account or self-hosted cluster. Teams register Endpoints here. The Registry is the source of truth for endpoint discovery, access control, and audit logging.

fraud-detection-prod
kyc-verification-v2
notifications-global
+ register new

How a Nexus Call Works

Walk through the step-by-step lifecycle of a Nexus Operation. Choose sync or async.

Caller Workflow
payments-ns
Nexus Endpoint
Routing + Auth
Handler Worker
fraud-ns
[ready] Press "Run Demo" to start the animation

Build It Step by Step

Walk through a real Nexus service from scratch using the samples-dotnet NexusSimple sample. Click each step.

select a step

      

Run a Real Example

Three official Nexus samples — pick your language and run locally in minutes.

samples-dotnet / NexusSimple

Defines a typed IHelloService interface with sync Echo and async SayHello (workflow-backed) operations across two namespaces.

View on GitHub

Setup

#Create two namespaces + a Nexus endpoint first (see README)
$git clone https://github.com/temporalio/samples-dotnet && cd samples-dotnet/src/NexusSimple

Run (3 terminals)

T1 $dotnet run handler-worker
T2 $dotnet run caller-worker
T3 $dotnet run caller-workflow
# Output: ¡Hola! Temporal 👋
samples-go / nexus

Go implementation of the same Hello/Echo pattern with sync and workflow-backed async operations.

View on GitHub
$git clone https://github.com/temporalio/samples-go && cd samples-go/nexus
T1 $go run ./handler/worker
T2 $go run ./caller/worker
T3 $go run ./caller/starter
samples-typescript / nexus-hello

TypeScript version using nexus-rpc and @temporalio/nexus.

View on GitHub Open in StackBlitz
$git clone https://github.com/temporalio/samples-typescript && cd samples-typescript/nexus-hello && npm install
T1 $npm run handler-worker
T2 $npm run caller-worker
T3 $npm run caller-workflow

Test Your Understanding

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