HATEOAS:绝对或相对 URL?

问题描述

在使用 HATEOAS 设计 RESTful Web 服务时，将链接显示为完整 URL ("http://server:port/application/customers/1234") 与路径(/application/customers/1234")?

In designing a RESTful Web Service using HATEOAS, what are the pros and cons of showing a link as a complete URL ("http://server:port/application/customers/1234") vs. just the path ("/application/customers/1234")?

推荐答案

当人们说相对 URI"时，会有一种微妙的概念歧义.

There is a subtle conceptual ambiguity when people say "relative URI".

根据RFC3986 的定义，通用 URI 包含:

By RFC3986's definition, a generic URI contains:

  URI         = scheme ":" hier-part [ "?" query ] [ "#" fragment ]

  hier-part   = "//" authority path-abempty
              / path-absolute
              / path-rootless
              / path-empty

     foo://example.com:8042/over/there?name=ferret#nose
     \_/   \______________/\_________/ \_________/ \__/
      |           |            |            |        |
   scheme     authority       path        query   fragment

棘手的是，当省略了方案和权限时，路径"部分本身可以是绝对路径(以 / 开头)或无根"相对路径.示例:

The tricky thing is, when scheme and authority are omitted, the "path" part itself can be either an absolute path (starts with /) or a "rootless" relative path. Examples:

1. 绝对 URI 或完整 URI:"http://example.com:8042/over/there?name=ferret"
2. 这是一个相对uri，具有绝对路径:/over/there
3. 这是一个相对uri，带有相对路径:here or ./here or ../here或等

1. An absolute URI or a full URI: "http://example.com:8042/over/there?name=ferret"
2. And this is a relative uri, with absolute path: /over/there
3. And this is a relative uri, with relative path: here or ./here or ../here or etc.

因此，如果问题是服务器是否应该在静态响应中生成相对路径"，那么答案是否"，并且 此处提供详细原因.我认为大多数人(包括我)反对相对 URI"实际上是反对相对路径".

So, if the question was "whether a server should produce relative path in restful response", the answer is "No" and the detail reason is available here.I think most people (include me) against "relative URI" are actually against "relative path".

并且在实践中，大多数服务器端 MVC 框架可以轻松生成具有绝对路径的相对 URI，例如 /absolute/path/to/the/controller，以及问题变成了服务器实现是否应该在绝对路径前添加 scheme://hostname:port 前缀".就像OP的问题一样.我不太确定这个.

And in practice, most server-side MVC framework can easily generate relative URI with absolute path such as /absolute/path/to/the/controller, and the question becomes "whether the server implementation should prefix a scheme://hostname:port in front of the absolute path". Like the OP's question. I am not quite sure about this one.

一方面，我仍然认为建议服务器返回完整的 uri.但是，服务器应该永远不要硬编码hostname:port 像这样的源代码中的东西(否则我宁愿回退到具有绝对路径的相对 uri).解决方案是服务器端始终从 HTTP 请求的主机"标头中获取该前缀.不过不确定这是否适用于所有情况.

On the one hand, I still think server returning a full uri is recommended. However, the server should never hardcode the hostname:port thing inside source code like this (otherwise I would rather fallback to relative uri with absolute path). Solution is server-side always obtaining that prefix from HTTP request's "Host" header. Not sure whether this works for every situations though.

另一方面，客户端连接http://example.com:8042和绝对路径似乎不是很麻烦.毕竟，客户端在向服务器发送请求时已经知道该方案和域名了吧?

On the other hand, it seems not very troublesome for the client to concatenate the http://example.com:8042 and the absolute path. After all, the client already know that scheme and domain name when it send the request to the server right?

总而言之，我会说，建议使用绝对 URI，可能回退到具有绝对路径的相对 URI，永远不要使用相对路径.

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