@loopback/docs/site/apidocs/rest.middlewaresequence.md

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---
lang: en
title: 'API docs: rest.middlewaresequence'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/rest
permalink: /doc/en/lb4/apidocs.rest.middlewaresequence.html
---

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[Home](./index.md) &gt; [@loopback/rest](./rest.md) &gt; [MiddlewareSequence](./rest.middlewaresequence.md)

## MiddlewareSequence class

A sequence implementation using middleware chains

<b>Signature:</b>

```typescript
export declare class MiddlewareSequence implements SequenceHandler 
```
<b>Implements:</b> [SequenceHandler](./rest.sequencehandler.md)

## Constructors

|  Constructor | Modifiers | Description |
|  --- | --- | --- |
|  [(constructor)(context, invokeMiddleware, options)](./rest.middlewaresequence._constructor_.md) |  | Constructor: Injects <code>InvokeMiddleware</code> and <code>InvokeMiddlewareOptions</code> |

## Properties

|  Property | Modifiers | Type | Description |
|  --- | --- | --- | --- |
|  [defaultOptions](./rest.middlewaresequence.defaultoptions.md) | <code>static</code> | [InvokeMiddlewareOptions](./express.invokemiddlewareoptions.md) |  |
|  [invokeMiddleware](./rest.middlewaresequence.invokemiddleware.md) |  | [InvokeMiddleware](./express.invokemiddleware.md) |  |
|  [options](./rest.middlewaresequence.options.md) |  | [InvokeMiddlewareOptions](./express.invokemiddlewareoptions.md) |  |

## Methods

|  Method | Modifiers | Description |
|  --- | --- | --- |
|  [handle(context)](./rest.middlewaresequence.handle.md) |  | Runs the default sequence. Given a handler context (request and response), running the sequence will produce a response or an error.<!-- -->Default sequence executes these groups of middleware:<!-- -->- <code>cors</code>: Enforces <code>CORS</code> - <code>openApiSpec</code>: Serves OpenAPI specs - <code>findRoute</code>: Finds the appropriate controller method, swagger spec and args for invocation - <code>parseParams</code>: Parses HTTP request to get API argument list - <code>invokeMethod</code>: Invokes the API which is defined in the Application controller method<!-- -->In front of the groups above, we have a special middleware called <code>sendResponse</code>, which first invokes downstream middleware to get a result and handles the result or error respectively.<!-- -->- Writes the result from API into the HTTP response (if the HTTP response has not been produced yet by the middleware chain. - Catches error logs it using 'logError' if any of the above steps in the sequence fails with an error. |