根据Richardson成熟度模型，问题不是REST vs. RPC，而是多少REST?

从这个角度来看，REST标准的遵从性可以分为4个级别。

0级:从动作和参数的角度考虑。正如本文所解释的，这在本质上等同于JSON-RPC(本文对XML-RPC进行了解释，但两者的参数相同)。 第一级:从资源的角度考虑。与资源相关的所有内容都属于同一个URL 第2级:使用HTTP动词 第三级:HATEOAS

According to the creator of REST standard, only level 3 services can be called RESTful. However, this is a metric of compliance, not quality. If you just want to call a remote function that does a calculation, it probably makes no sense to have relevant hypermedia links in the response, neither differentiation of behavior based on the HTTP verb used. So, a such call inherently tends to be more RPC-like. However, lower compliance level does not necessarily mean statefulness, or higher coupling. Probably, instead of thinking REST vs. RPC, you should use as much REST as possible, but no more. Do not twist your application just to fit with the RESTful compliance standards.

RPC的基本问题是耦合。RPC客户端以多种方式与服务实现紧密耦合，在不破坏客户端的情况下更改服务实现变得非常困难:

客户需要知道过程名称; 程序参数顺序，类型和计数事项。在不破坏客户端实现的情况下，在服务器端改变过程签名(参数的数量、参数的顺序、参数类型等)并不是那么容易的; RPC样式只公开过程端点+过程参数。客户不可能决定下一步该做什么。

另一方面，在REST风格中，通过在表示(HTTP报头+表示)中包含控制信息来引导客户端是非常容易的。例如:

It's possible (and actually mandatory) to embed links annotated with link relation types which convey meanings of these URIs; Client implementations do not need to depend on particular procedure names and arguments. Instead, clients depend on message formats. This creates possibility to use already implemented libraries for particular media formats (e.g. Atom, HTML, Collection+JSON, HAL etc...) It's possible to easily change URIs without breaking clients as far as they only depend on registered (or domain specific) link relations; It's possible to embed form-like structures in representations, giving clients the possibility to expose these descriptions as UI capabilities if the end user is human; Support for caching is additional advantage; Standardised status codes;

在REST方面还有更多的区别和优势。

我过去一直是REST的忠实粉丝，它在纸上比RPC有很多优势。你可以给客户端提供不同的内容类型、缓存、HTTP状态代码的重用，你可以通过API引导客户端，如果API不是大部分都是自解释的，你可以在API中嵌入文档。

But my experience has been that in practice this doesn't hold up and instead you do a lot of unnecessary work to get everything right. Also the HTTP status codes often don't map to your domain logic exactly and using them in your context often feels a bit forced. But the worst thing about REST in my opinion is that you spend a lot of time to design your resources and the interactions they allow. And whenever you do some major additions to your API you hope you find a good solution to add the new functionality and you didn't design yourself into a corner already.

This often feels like a waste of time to me because most of the time I already have a perfectly fine and obvious idea about how to model an API as a set of remote procedure calls. And if I have gone through all this effort to model my problem inside the constraints of REST the next problem is how to call it from the client? Our programs are based on calling procedures so building a good RPC client library is easy, building a good REST client library not so much and in most cases you will just map back from your REST API on the server to a set of procedures in your client library.

正因为如此，今天对我来说，RPC感觉更简单、更自然。不过，我真正怀念的是一个一致的框架，它可以很容易地编写自描述和可互操作的RPC服务。因此，我创建了自己的项目，尝试新的方法使RPC对我自己更容易，也许其他人也会发现它有用:https://github.com/aheck/reflectrpc

首先，HTTP-REST是一种“具象状态传输”体系结构。这意味着很多有趣的事情:

您的API将是无状态的，因此更容易设计(在复杂的自动机中很容易忘记转换)，并与独立的软件部件集成。 你将被引导设计安全的读取方法，这将是容易缓存和集成。 你会被引导把写方法设计成幂等的方法，这样可以更好地处理超时。

其次，HTTP- rest完全兼容HTTP(请参阅前一部分中的“安全”和“幂等”)，因此您将能够重用HTTP库(适用于所有现有语言)和HTTP反向代理，这将使您能够实现高级功能(缓存、身份验证、压缩、重定向、重写、日志记录等)，而无需代码行。

最后但并非最不重要的是，根据HTTP 1.1的设计者(以及REST的发明者)的说法，使用HTTP作为RPC协议是一个巨大的错误:http://www.ics.uci.edu/~fielding/pubs/dissertation/evaluation.htm#sec_6_5_2

我认为，一如既往，这取决于……

REST具有广泛的公众支持的巨大优势，这意味着有大量的工具和书籍。如果你需要制作一个API，让来自不同组织的大量消费者使用，那么只有一个原因:它是受欢迎的。作为一种协议，它当然是完全失败的，因为有太多完全不同的方法来将命令映射到URL/动词/响应。

因此，当你编写一个需要与后端对话的单页web应用程序时，我认为REST太复杂了。在这种情况下，你不必担心长期的兼容性，因为应用程序和API可以一起发展。

I once started with REST for a single page web app but the fine grained commands between the web app and the server quickly drove me crazy. Should I encode it as a path parameter? In the body? A query parameter? A header? After the URL/Verb/Response design I then had to code this mess in Javascript, the decoder in Java and then call the actual method. Although there are lots of tools for it, it is really tricky to not get any HTTP semantics in your domain code, which is really bad practice. (Cohesion)

尝试为中等复杂的站点制作一个Swagger/OpenAPI文件，并将其与该文件中描述远程过程的单个Java接口进行比较。复杂性的增长是惊人的。

因此，对于单页web应用程序，我从REST切换到JSON-RPC。aI开发了一个小型库，在服务器上编码Java接口，并将其传送到浏览器。在浏览器中，这为为每个函数返回承诺的应用程序代码创建了一个代理。

同样，REST也有它的地位，因为它很有名，因此得到了很好的支持。认识到底层的无状态资源哲学和层次模型也很重要。然而，这些原则同样可以在RPC模型中使用。JSON RPC工作于HTTP之上，因此它在这方面具有与REST相同的优势。不同之处在于，当您不可避免地遇到这些不能很好地映射到这些原则的函数时，您不必被迫做大量不必要的工作。

最好在REST和JSON-RPC之间选择JSON-RPC，为web应用程序开发一个更容易理解的API。JSON-RPC是首选，因为它对方法调用和通信的映射很容易理解。

选择最合适的方法取决于约束条件或主要目标。例如，只要性能是一个主要特征，就建议使用JSON-RPC(例如，高性能计算)。但是，如果主要目标是不可知，以便提供一个通用的接口供其他人推断，则建议使用REST。如果两个目标都需要实现，建议同时包含两个协议。

The fact which actually splits REST from JSON-RPC is that it trails a series of carefully thought out constraints- confirming architectural flexibility. The constraints take in ensuring that the client as well as server are able to grow independently of each other (changes can be made without messing up with the application of client), the calls are stateless (the state is regarded as hypermedia), a uniform interface is offered for interactions, the API is advanced on a layered system (Hall, 2010). JSON-RPC is rapid and easy to consume, however as mentioned resources as well as parameters are tightly coupled and it is likely to depend on verbs (api/addUser, api/deleteUser) using GET/ POST whereas REST delivers loosely coupled resources (api/users) in a HTTP. REST API depends up on several HTTP methods such as GET, PUT, POST, DELETE, PATCH. REST is slightly tougher for inexperienced developers to implement.

JSON (denoted as JavaScript Object Notation) being a lightweight data-interchange format, is easy for humans to read as well as write. It is hassle free for machines to parse and generate. JSON is a text format which is entirely language independent but practices conventions that are acquainted to programmers of the family of languages, consisting of C#, C, C++, Java, Perl, JavaScript, Python, and numerous others. Such properties make JSON a perfect data-interchange language and a better choice to opt for.