---
title: "Components"
description: "A Dex application runs on four components: your application, the server, the"
canonical_url: "https://docs.superdurable.io/components/"
source: "docs/content/components/index.mdx"
locale: "en"
---

# Components

A Dex application runs on four components: your application, the server, the
CLI, and Web. You write the application. Dex provides the rest.

| Component                                                             | What it does                                                                                                                         |
| --------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------ |
| [Application](https://docs.superdurable.io/components/application.md) | Your Workers and Clients. Workers host Flow definitions and run Steps and RPCs. Clients start Flows, call RPCs, and read Attributes. |
| [Server](https://docs.superdurable.io/components/server.md)           | server-zd stores Flow state and hands work to Workers.                                                                               |
| [CLI](https://docs.superdurable.io/components/cli.md)                 | **dexcli** runs a local Dex and operates Flows from a shell.                                                                         |
| [Web](https://docs.superdurable.io/components/web.md)                 | Dex Web is the operator UI for inspecting and acting on Flows.                                                                       |

## How they fit together

```text
Client  ──▶ server-zd ◀── Worker
Dex Web ──▶     │
dexcli  ──▶     ├──▶ object storage
                └──▶ PostgreSQL (Attribute Store sync)
```

Workers, Clients, Dex Web, and **dexcli** all connect to the server's API port.
A Worker opens outbound streams to the server and never listens for calls. The
server keeps Flow state in object storage. It can also write selected Attributes
to PostgreSQL for your own queries. See
[Keep data after the Flow](https://docs.superdurable.io/concepts/primitives/attribute.md#attribute-store-projection).

## Local and production

| Component   | Local development               | Production                                        |
| ----------- | ------------------------------- | ------------------------------------------------- |
| Server      | **dexcli dev** starts server-zd | **dex-server-zd serve** with object storage       |
| Web         | **dexcli dev** starts Dex Web   | A separate **dex-web** process, or **dexcli web** |
| Application | Your Worker process             | Your Worker service, scaled like any service      |

Each component page links to its [Developer Reference](https://docs.superdurable.io/reference.md), which has
the configuration, limits, and version details.