# Patterns for shared messages

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You can store your events, commands and queries in any folder in your EventCatalog.

Here are some common usecases:

* [Messages defined by the service](/docs/development/guides/messages/common/shared-messages-across-boundaries.md#messages-defined-by-the-service)
* [Messages defined at a domain level](/docs/development/guides/messages/common/shared-messages-across-boundaries.md#define-messages-at-a-domain-level)
* [Messages defined at a system level](/docs/development/guides/messages/common/shared-messages-across-boundaries.md#define-messages-at-a-system-level)

### Messages defined by the service[​](#messages-defined-by-the-service "Direct link to Messages defined by the service")

If you want to keep your message definition close to the service that producers or consumes it you can store them in the `/services` folder.

In the example below the `OrderPlaced` event, `AddOrder` command and `GetOrder` query are defined in the `/services/Orders` folder.

```
services/
  Orders/
    events/
      OrderPlaced/
        index.mdx
    commands/
      AddOrder/
        index.mdx
    queries/
      GetOrder/
        index.mdx
```

### Define messages at a domain level[​](#define-messages-at-a-domain-level "Direct link to Define messages at a domain level")

If you want to share messages across multiple services you can define them in the `/domains` folder.

In the example below the `OrderPlaced` event, `AddOrder` command and `GetOrder` query are defined in the `/domains/Orders` folder.

```
domains/
  Orders/
     <!-- The domain documentation -->
    index.mdx
    <!-- Here we store our /events, /commands and /queries -->
    events/
      OrderPlaced/
        index.mdx
```

### Define messages at a system level[​](#define-messages-at-a-system-level "Direct link to Define messages at a system level")

If you want to share messages across all your domains you can define them in the root of your catalog.

In the example below the `OrderPlaced` event, `AddOrder` command and `GetOrder` query are defined in the root of your catalog.

```
events/
  OrderPlaced/
    index.mdx
commands/
  AddOrder/
    index.mdx
queries/
  GetOrder/
    index.mdx
```