在Rest Web服务请求中返回文件的正确方法是什么？

Question

I need to return a file in my webservice. I am bit in doubt of what is the best/correct/execpted way. (I am using JSON).

I can:

1. simply return the file (as normal download) with the correct mime type, etc. via HTTP
2. encode de file (eg: Base64 or other) and send it inside the JSON answer
3. return a json answer with the url where the file can be found.

Answer 1

All three are valid, depending on the client's needs, so why not make it the client's choice?

Let's say it's an image/jpeg file:

If the client sent the Accept: image/jpeg header, you return the file as a normal download.

If the client sent the Accept: image/jpeg header and the Accept-Encoding: base64 , you return it as a normal download, Base64 encoded.

If the client sends the Accept: text/uri-list header, you return a plain text response with the URI for the image stored somewhere else.

There are no standard mimetypes to return base64 or links inside json, but you can use some standard of your own and create a vnd mimetype, as long as you document it.