Webservice Design Style : REST vs SOAP vs XML-RPC

REST(REpresentational State Transfer)

REST是並不是一種標準，只是一種Web Service的設計風格。RESTful則是另一個用來定義Web Service的名詞。

Representational State Transfer or REST basically means that each unique URL is a representation of some object. You can get the contents of that object using an HTTP GET, to delete it, you then might use a POST, PUT, or DELETE to modify the object (in practice most of the services use a POST for this).

It is not necessary to use XML as a data interchange format in REST. The format of information(representation) returned can be in XML, JSON, plain text or even in HTML format.

REST architecture is basically focused on two things : Resources and Interface.

嚴格來說REST符合以下幾個條件:

應用程式的狀態跟功能拆成 resources

每個 resource 使用獨一無二用來當作超連結的通用定位語法(在WWW中即URI)

所有 resources 共用一致的介面在 client 跟 resource 之間轉換狀態，包括:

• 一組有限的良好定義操作 well-defined operations (在HTTP中即 GET/POST/PUT/DELETE)
• 一組有限的內容格式 content types,也許包括 可執行的程式碼 code-on-demand (在WWW中即Javascript)

SOAP(Simple Object Access Protocol)

SOAP message are transferred forming the SOAP-Envelope. SOAP is widely criticized for it’s design complexity.

RPC(Remote Procedure Call)

在XML的世界裏頭，有兩種方式來實作RPC(Remote Procedure Call): 

1. XML-based RPC 

2. SOAP

RPC 應用程式曝露一或多個網路物件，每個有特定的 functions 可以呼叫。在 client 與物件溝通之前，它必須知道這個物件的知識來操作。

REST vs SOAP

The main advantages of REST web services are:

• Lightweight – not a lot of extra xml markup
• Human Readable Results
• Easy to build – no toolkits required

SOAP also has some advantages:

• Easy to consume – sometimes
• Rigid – type checking, adheres to a contract
• Development tools

Reference

1. http://maxivak.com/rest-vs-xml-rpc-vs-soap/

2. http://ihower.tw/blog/archives/1542
3. Why RESTful Design for the Cloud is Best, http://www.slideshare.net/galderz/restful-designjbw-summit2010