CODEWITHSUNDEEP
jsonhttp-headers
Win Myo Htet
Win Myo Htet

Reputation: 5457

Using Json string in the Http Header

Recently I run into some weird issue with http header usage ( Adding multiple custom http request headers mystery) To avoid the problem at that time, I have put the fields into json string and add that json string into header instead of adding those fields into separate http headers.

For example, instead of 

request.addHeader("UserName", mUserName);
request.addHeader("AuthToken", mAuthorizationToken);
request.addHeader("clientId","android_client");

I have created a json string and add it to the single header

String jsonStr="{\"UserName\":\"myname\",\"AuthToken\":\"123456\",\"clientId\":\"android_client\"}";
request.addHeader("JSonStr",jsonStr);

Since I am new to writing Rest and dealing with the Http stuff, I don't know if my usage is proper or not. I would appreciate some insight into this.

Some links

http://lists.w3.org/Archives/Public/ietf-http-wg/2011OctDec/0133.html

Upvotes: 36

Views: 66473

Answers (5)

KarelHusa
KarelHusa

Reputation: 2263

In the design-first age the OpenAPI specification gives another perspective:

  • an HTTP header parameter may be an object, e.g. object X-MyHeader is

    {"role": "admin", "firstName": "Alex"}

  • however, within the HTTP request/response the value is serialized, e.g.

    X-MyHeader: role=admin,firstName=Alex

Upvotes: 3

jchook
jchook

Reputation: 7220

Yes, you may use JSON in HTTP headers, given some limitations.

According to the HTTP spec, your header field-body may only contain visible ASCII characters, tab, and space.

Since many JSON encoders (e.g. json_encode in PHP) will encode invisible or non-ASCII characters (e.g. "é" becomes "\u00e9"), you often don't need to worry about this.

Check the docs for your particular encoder or test it, though, because JSON strings technically allow most any Unicode character. For example, in JavaScript JSON.stringify() does not escape multibyte Unicode, by default. However, you can easily modify it to do so, e.g.

var charsToEncode = /[\u007f-\uffff]/g;
function http_header_safe_json(v) {
  return JSON.stringify(v).replace(charsToEncode,
    function(c) {
      return '\\u'+('000'+c.charCodeAt(0).toString(16)).slice(-4);
    }
  );
}

Source

Alternatively, you can do as @rocketspacer suggested and base64-encode the JSON before inserting it into the header field (e.g. how JWT does it). This makes the JSON unreadable (by humans) in the header, but ensures that it will conform to the spec.

Worth noting, the original ARPA spec (RFC 822) has a special description of this exact use case, and the spirit of this echoes in later specs such as RFC 7230:

Certain field-bodies of headers may be interpreted according to an internal syntax that some systems may wish to parse.

Also, RFC 822 and RFC 7230 explicitly give no length constraints:

HTTP does not place a predefined limit on the length of each header field or on the length of the header section as a whole, as described in Section 2.5.

Upvotes: 44

tu4n
tu4n

Reputation: 4450

Base64encode it before sending. Just like how JSON Web Token do it.
Here's a NodeJs Example:

const myJsonStr = JSON.stringify(myData);
const headerFriendlyStr = Buffer.from(myJsonStr, 'utf8').toString('base64');
res.addHeader('foo', headerFriendlyStr);

Decode it when you need reading:

const myBase64Str = req.headers['foo'];
const myJsonStr = Buffer.from(myBase64Str, 'base64').toString('utf8');
const myData = JSON.parse(myJsonStr);

Upvotes: 18

Win Myo Htet
Win Myo Htet

Reputation: 5457

From what I understand using a json string in the header option is not as much of an abuse of usage as using http DELETE for http GET, thus there has even been proposal to use json in http header. Of course more thorough insights are still welcome and the accepted answer is still to be given.

Upvotes: 5

Kevin Junghans
Kevin Junghans

Reputation: 17540

Generally speaking you do not send data in the header for a REST API. If you need to send a lot of data it best to use an HTTP POST and send the data in the body of the request. But it looks like you are trying to pass credentials in the header, which some REST API's do use. Here is an example for passing the credentials in a REST API for a service called SMSIfied, which allows you to send SMS text message via the Internet. This example is using basic authentication, which is a a common technique for REST API's. But you will need to use SSL with this technique to make it secure. Here is an example on how to implement basic authentication with WCF and REST.

Upvotes: 7

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