# MessageRequestProperties

**Kind:** Interface

**Source:** [`packages/microservices/listener-metadata-explorer.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/listener-metadata-explorer.ts#L30)

**Part of:** [Microservices](subsystem-packages-microservices)

`MessageRequestProperties` describes the request and reply message patterns associated with a microservice listener. It groups the inbound `requestPattern` with the corresponding outbound `replyPattern`, allowing metadata exploration tools to identify request-response communication contracts.

## Properties

| Property | Type |
|---|---|
| `requestPattern` | `PatternMetadata` |
| `replyPattern` | `PatternMetadata` |

## Diagram

```mermaid
graph LR
  Listener[Microservice Listener Metadata] --> Properties[MessageRequestProperties]
  Properties --> Request[requestPattern: PatternMetadata]
  Properties --> Reply[replyPattern: PatternMetadata]
  Request --> Incoming[Incoming request message]
  Reply --> Outgoing[Reply message]
```

## Usage

```ts
import type { MessageRequestProperties } from './listener-metadata-explorer';

const messageRequest: MessageRequestProperties = {
  requestPattern: {
    pattern: 'users.get',
  },
  replyPattern: {
    pattern: 'users.get.reply',
  },
};

// Use the metadata when inspecting or documenting listener contracts.
console.log(
  `Request pattern: ${messageRequest.requestPattern.pattern}`,
);
console.log(
  `Reply pattern: ${messageRequest.replyPattern.pattern}`,
);
```

## AI Coding Instructions

- Keep `requestPattern` and `replyPattern` paired when representing request-response message handlers.
- Use valid `PatternMetadata` objects for both fields; do not substitute raw strings unless the metadata type explicitly permits them.
- Preserve the distinction between request and reply patterns when inspecting listener metadata or generating documentation.
- Update consumers of listener metadata if the shape or semantics of either pattern changes.