OverpassClient - Overpass API Wrapper for OpenStreetMap

Overview

OverpassClient is designed to simplify interaction with the Overpass API, used for querying OpenStreetMap (OSM) data. This wrapper provides an easy-to-use interface for retrieving geographic objects like nodes, ways, and relations while handling common issues such as retries, timeouts, and network failures.

Why?

Interacting with the Overpass API directly can be complex due to common issues like network failures, timeouts, and data size concerns. This wrapper addresses those issues by:

• Automatic Retries: The client automatically retries failed requests with exponential backoff and Jitter.
• Network Resilience: It reduces downtime caused by intermittent network issues or server limitations.
• Error Handling: Gracefully handles Overpass-specific errors, retries, and timeouts, including a custom error class for different error scenarios.

This is ideal for developers who want to interact with OSM data without worrying about low-level request handling and retries.

Features

• Axios Integration: Uses Axios for making HTTP requests, providing flexibility and familiarity.
• Automatic Retries with Exponential Backoff and Jitter: Built-in retry logic that progressively delays retries with exponential backoff and jitter to avoid overwhelming the server.
• Observables: Handles asynchronous operations efficiently, with easy composition and transformation of the data flow.
• Node, Way & Relation Support: Supports querying node, way and relation data, enabling more accurate searches.
• Caching: Caches responses to optimize performance for repeated queries, using LRU cache.
• Flexible Querying: Easily query elements by ID, bounding box, or radius with customizable tag filters.

How It Solves Common Problems

1. Retries and Exponential Backoff:

   • If a request fails, the client automatically retries it with an exponentially increasing delay, including jitter between attempts, ensuring the server isn't overwhelmed.
   • This approach significantly improves reliability, especially when dealing with intermittent issues.

2. Handling Network and Server Failures:

   • The use of Observables, retry logic, and error handling ensures that transient failures (such as network glitches, rate limiting, or API downtime) don't lead to repeated failures, providing a smoother experience for users.

3. Simplified API:

   • The library abstracts away complex HTTP request handling and error management, allowing developers to focus on higher-level application logic rather than worrying about the specifics of interacting with the Overpass API.

Installation

npm install @andreasnicolaou/overpass-client

Usage

Importing the Library

import { OverpassClient } from '@andreasnicolaou/overpass-client';

Initialize the Library

this.overpassClient = new OverpassClient();

Query a specific element by ID

this.overpassClient.getElement('way', 452).subscribe((response) => {
  console.log(response);
});

Query elements within a bounding box

const tags = { amenity: ['cafe', 'restaurant'] };
const bbox: [number, number, number, number] = [48.85, 2.29, 48.87, 2.35]; // [minLat, minLon, maxLat, maxLon]
this.overpassClient.getElementsByBoundingBox(tags, bbox).subscribe((response) => {
  console.log(response);
});

Query elements within a radius from a center point

const lat = 48.85;
const lon = 2.35;
const radius = 500;
this.overpassClient.getElementsByRadius(tags, lat, lon, radius).subscribe((response) => {
  console.log(response);
});

API

| Method | Description | Parameters | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | clearCache() | Clear the LRU cache entirely. | None | | getElement(type: ElementType, id: number, outputFormat: string = 'out;') | Fetches a specific element (node, way, or relation) by its ID. | - type: The type of element ('node', 'way', 'relation').- id: The ID of the element.- outputFormat: The Overpass QL output format (default: 'out;'). | | getElementsByBoundingBox(tags: Record<string, string[]>, bbox: [number, number, number, number], elements: ElementType[] = ['node', 'way', 'relation'], outputFormat: string = 'out center;') | Fetches elements with specified tags within a given bounding box. | - tags: A dictionary of tag types and their possible values.- bbox: A bounding box in the format [minLat, minLon, maxLat, maxLon].- elements: The element types to include in the query (default: 'node', 'way', 'relation').- outputFormat: The Overpass QL output format (default: 'out center;'). | | getElementsByRadius(tags: Record<string, string[]>, lat: number, lon: number, radius: number, elements: ElementType[] = ['node', 'way', 'relation'], outputFormat: string = 'out center;') | Fetches elements with specified tags within a given radius from a point. | - tags: A dictionary of tag types and their possible values.- lat: Latitude of the center point.- lon: Longitude of the center point.- radius: Search radius in meters.- elements: The element types to include in the query (default: 'node', 'way', 'relation').- outputFormat: The Overpass QL output format (default: 'out center;'). |

References

• Overpass API - Public Instances
• Overpass Turbo

Contributing

Contributions are welcome! If you encounter issues or have ideas to enhance the library, feel free to submit an issue or pull request.