Using a Body With an HTTP Get Method Is Still a Bad Idea

The HTTP GET Method and Using a Body With the Request

The Hypertext Transfer Protocol (HTTP) has several methods, or "verbs," to allow clients and servers to communicate effectively. One of the most commonly used methods is the GET method, which retrieves data from a server. While HTTP specifications do not forbid sending a body with a GET request, doing so is non-standard and can lead to various problems.

Background: What Is the HTTP GET Method?

In HTTP, the GET method is designed to retrieve data from a server without causing any side effects. Typically, this data is fetched based on parameters sent as part of the URL's query string. For instance, in a URL like http://example.com/?key=value represents a parameter passed to the server.

Can a Body Be Sent With an HTTP GET Request?

Technically, yes. The HTTP/1.1 specification (RFC 7231) does not explicitly forbid including a body in a GET request. However, it states that a GET request body has no defined semantics, meaning that the server is under no obligation to understand or use it. In practice, the inclusion of a request body with GET has been a contentious issue.

Reasons Why Including a Body With GET Is Not a Good Idea:

1. Semantics Misalignment: HTTP methods have semantic meanings. A GET request signifies a read operation, with no side-effects, while request bodies typically convey data to be processed by the server. Sending a body with a GET muddies this clear distinction.
2. Server Incompatibility: Many servers and intermediaries might ignore the body of a GET request or even reject the request altogether.
3. Caching Issues: HTTP caching mechanisms rely on the predictability of request methods. A GET request with a body could disrupt these mechanisms because caches might not consider the body when determining a cache hit or miss.
4. Potential Security Concerns: As it's uncommon, systems might not anticipate or correctly handle a body in a GET request. This oversight could expose vulnerabilities.

Potential Reasons to Use a Body With GET:

1. Complex Querying: Some applications, especially those that require complex querying (like certain database searches), might find it more straightforward to convey this information in a body rather than a URL.
2. Uniformity in Design: If an application design uses bodies to send data in other methods (POST, PUT), one might consider using a body with GET for the sake of consistency.
3. Avoiding Long URLs: URLs can have length restrictions. For instance, Internet Explorer has a maximum URL length of 2048 characters. Using a body can help sidestep this limitation.

Alternatives to Sending a Body With GET:

1. Use the POST Method: If there's a need to send a significant amount of data to the server for processing and retrieval, the POST method might be more appropriate.
2. URL Encoding: For less complex data requirements, parameters can be URL-encoded and appended to the request URL.
3. Custom Headers: Some information can be passed using custom HTTP headers, avoiding the need for a body or long URLs.

Conclusion

While it's technically possible to send a body with an HTTP GET request, it's generally not recommended due to the potential for semantic confusion, technical incompatibilities, and other challenges. It's essential to weigh the pros and cons in the context of specific application needs and, when in doubt, adhere to standard practices to ensure the broadest compatibility and best user experience.