Rest Api | Api Usage | Elasticsearch Tutorial

Introduction to REST API

REST (Representational State Transfer) is an architectural style for designing networked applications. It relies on a stateless, client-server, cacheable communications protocol -- the HTTP. REST is often used in conjunction with JSON or XML to provide a lightweight communication format.

Understanding REST Concepts

Key concepts in REST include:

Resources: Anything that can be named, such as a document, image, temporal service (e.g., "today's weather in Los Angeles"), a collection of other resources, a non-virtual object (e.g., a person), and so on.
HTTP Methods: The primary or most-commonly-used HTTP methods are POST, GET, PUT, PATCH, and DELETE.
Endpoints: The URL of the API server that provides access to the resources.

Setting Up a REST API

To set up a REST API, you'll need a server and a client. The server hosts the API, and the client makes requests to it.

Example of a basic REST API using Node.js and Express:

const express = require('express');
const app = express();
const port = 3000;

app.use(express.json());

let items = [{ id: 1, name: 'Item 1' }, { id: 2, name: 'Item 2' }];

app.get('/items', (req, res) => {
  res.json(items);
});

app.post('/items', (req, res) => {
  const newItem = { id: items.length + 1, ...req.body };
  items.push(newItem);
  res.status(201).json(newItem);
});

app.listen(port, () => {
  console.log(`Server running on port ${port}`);
});

Elasticsearch and REST API

Elasticsearch is a distributed, RESTful search and analytics engine. It's used for a variety of use cases such as log and event data analysis, full-text search, and more. Elasticsearch API allows you to interact with your Elasticsearch cluster.

Basic Elasticsearch REST API Operations

Below are some basic operations that you can perform using Elasticsearch REST API:

Indexing a Document

You can index a document using a PUT request:

PUT /my-index/_doc/1
{
  "name": "John Doe",
  "age": 29,
  "occupation": "Software Developer"
}

Retrieving a Document

To retrieve a document, use a GET request:

GET /my-index/_doc/1

Updating a Document

To update a document, use a POST request:

POST /my-index/_update/1
{
  "doc": {
    "age": 30
  }
}

Deleting a Document

To delete a document, use a DELETE request:

DELETE /my-index/_doc/1

Advanced Elasticsearch REST API Operations

Searching Documents

Elasticsearch provides a powerful search API that allows you to query your data in various ways. Here's an example of a basic search query:

GET /my-index/_search
{
  "query": {
    "match": {
      "occupation": "Software Developer"
    }
  }
}

Aggregations

Aggregations in Elasticsearch allow you to perform complex data analysis. Here's an example of a simple aggregation:

GET /my-index/_search
{
  "aggs": {
    "average_age": {
      "avg": {
        "field": "age"
      }
    }
  }
}

Conclusion

In this tutorial, we covered the basics of REST APIs, how to set one up, and how to use Elasticsearch's REST API for various operations. REST APIs are a powerful way to interact with web services, and understanding how to use them effectively is a crucial skill for modern developers.

Comprehensive Tutorial on REST API