$http request vs $resource service – Performance comparison

In AngularJS, both $http and $resource are used to interact with external web services, but they serve different purposes and have distinct features. Here’s a detailed comparison between $http and $resource, with a focus on performance, use cases, and how they affect your AngularJS application.

1. Introduction to $http and $resource

• $http Service:
  • $http is a core AngularJS service that is used to make HTTP requests to a server. It provides a low-level API to communicate with RESTful APIs, send GET, POST, PUT, DELETE requests, and handle responses.
  • It provides a flexible and customizable way to interact with web services, but requires you to manually handle various aspects of the request, such as URLs, request headers, and parsing responses.
• $resource Service:
  • $resource is a higher-level AngularJS service that simplifies interacting with RESTful APIs. It is built on top of $http but provides a more structured approach, especially for RESTful resources.
  • $resource uses a declarative API to define RESTful endpoints, making it easier to perform common operations like GET, POST, PUT, and DELETE without having to write repetitive code.

2. Performance Considerations

While both $http and $resource are designed for making HTTP requests, they are optimized differently. Here’s a performance comparison based on different use cases:

2.1 Request Customization:

• $http:
  • $http is more flexible, allowing you to fully customize the request, including URL, method, headers, and body. This means you have complete control over the request, but it also means you have to handle more boilerplate code for each request.
  • It is best for cases where you need highly customized requests that don’t fit well with a RESTful API pattern.
• $resource:
  • $resource is designed specifically for RESTful APIs, so it’s less flexible than $http in terms of customization. It abstracts many of the manual steps required in $http and offers a more concise way to interact with standard REST endpoints.
  • For simple and standard use cases (CRUD operations on resources), $resource can be more efficient as it reduces the amount of boilerplate code needed to handle these operations.

2.2 Overhead:

• $http:
  • $http has minimal overhead because it directly interacts with the HTTP API. There’s no additional abstraction layer. Each request is manually configured, meaning you are in full control of what is being sent and received.
  • Since it’s lower-level, performance can be better for complex requests, but more code and effort are required.
• $resource:
  • $resource introduces an additional abstraction layer over $http. While this can make your code cleaner and more concise, it does incur some overhead due to this abstraction. For each resource method (e.g., get(), save(), query()), $resource generates an HTTP request internally, which adds a small performance cost compared to $http.
  • However, for typical CRUD operations, the performance difference is negligible for most use cases and is outweighed by the simplicity it offers in the code.

2.3 Caching:

• $http:
  • $http does not provide built-in support for caching. If you need to cache HTTP responses, you would have to implement caching manually, which could lead to additional complexity and performance overhead in the application.
• $resource:
  • $resource has built-in caching capabilities. It can automatically cache GET requests and serve the cached results for repeated calls to the same endpoint. This can be very helpful in situations where you need to repeatedly fetch the same resource without the need for an additional HTTP request, improving performance in certain scenarios.

2.4 Ease of Use:

• $http:
  • $http is very flexible but requires more manual coding to handle repetitive tasks, such as handling response data, error handling, and setting up the request headers.
  • For non-standard API calls or complex configurations (e.g., working with multipart forms, custom headers, etc.), $http is more suitable.
• $resource:
  • $resource abstracts much of the repetitive work involved in making requests to RESTful APIs. It allows you to declare the API endpoints as a resource and define CRUD operations in a more declarative way. This reduces the need for repetitive code and is highly beneficial for standard use cases.

2.5 Complex Scenarios:

• $http:
  • $http is more versatile and capable of handling more complex scenarios (e.g., custom headers, complex payloads, etc.). If you are working with APIs that don’t follow the RESTful pattern or need to perform non-REST operations (e.g., custom actions or multipart uploads), $http gives you full control over the request.
• $resource:
  • $resource is best suited for standard RESTful APIs where the operations map to basic CRUD actions. If the API requires operations beyond simple GET, POST, PUT, and DELETE requests, $resource may not be the best choice, and $http would be more appropriate.

2.6 Error Handling:

• $http:
  • $http provides a detailed response structure where you can handle errors, status codes, and response data manually. This gives you more control over error handling and custom actions based on different status codes.
• $resource:
  • $resource also provides error handling, but it is generally abstracted away in favor of simplicity. While $resource provides error callbacks, its error handling is not as customizable or fine-grained as $http. For more complex error handling scenarios, $http is preferred.

3. Which One Should You Use?

• Use $http if:
  • You need full control over the HTTP requests.
  • You are dealing with complex APIs or APIs that don’t follow RESTful conventions.
  • You need to handle custom HTTP headers, timeouts, or need a specific request setup.
  • You require complex error handling or customization beyond basic CRUD operations.
• Use $resource if:
  • You are working with a standard RESTful API and want a more concise, easier-to-manage solution.
  • You need to perform basic CRUD operations without much customization.
  • You want to take advantage of built-in caching features to reduce the number of requests made to the server.
  • You want to write less code and have a cleaner, more declarative way to handle REST resources.

4. Performance Summary:

• For Standard CRUD Operations:
  • $resource will typically perform equally well as $http for simple operations. The overhead added by $resource is minimal for typical use cases, and the code simplicity it offers is beneficial in most scenarios.
• For Complex Custom Requests:
  • $http is preferred when dealing with custom APIs or when you need more control over the request and response. The flexibility of $http allows for optimized performance in scenarios that don’t fit well with REST.
• Caching and Redundant Requests:
  • $resource offers automatic caching for GET requests, which can improve performance when repeatedly fetching the same data. If your app frequently requests the same resource, using $resource can save bandwidth and reduce server load.