Question

在RESTful Web API一书中，作者建议公开一个配置文件并使用一种确认链接关系的内容类型。由JSON-LD扩展的Hydra似乎符合这些要求，我想在设计新API时使用它们。

我目前遇到了性能问题。假设我有一个在线自行车商店，我想要检索有关给定自行车车轮的信息。

根据Hydra规范，在我看来，我需要发送2个请求来获取有关车轮的详细信息。第一个要求是自行车本身：

GET /mybike HTTP/1.1
Host: wowbike.com

响应包含一个Hydra :: Link到轮子集合：

HTTP/1.1 200 OK
Content-Type: application/ld+json
{
  "@context" :
               {
                   "Bike": "/contexts/vocab#Bike"
               },
  "@id"      : "/mybike",
  "@type"    : "Bike",
  "size"     : "L",
  "wheels"   : "/mybike/wheels" // "wheels" is a "hydra:Link"
}

现在我可以向wheel资源发送第二个请求以获取详细信息：

GET /mybike/wheels HTTP/1.1
Host: wowbike.com

HTTP/1.1 200 OK
Content-Type: application/ld+json
{
    "@context":
               {
                   "Collection": "http://www.w3.org/ns/hydra/core#Collection",
                   "Wheel"     : "/contexts/vocab#Wheel"
               },
    "@type"   : "Collection",
    "@id"     : "/mybike/wheels",
    "member"  :
                [
                 {
                   "@id"   : "/mybike/wheels/firstwheel",
                   "@type" : "Wheel",
                   "color" : "blue"
                 },
                 {
                   "@id"   : "/mybike/wheels/secondwheel",
                   "@type" : "Wheel",
                   "color" : "white"
                 }
                ]
}

发送单个请求并获得如下所示的响应是否有效？

GET /mybike HTTP/1.1
Host: wowbike.com

HTTP/1.1 200 OK
Content-Type: application/ld+json
{
  "@context" : 
               {
                   "Collection": "http://www.w3.org/ns/hydra/core#Collection",
                   "Bike"      : "/contexts/vocab#Bike",
                   "Wheel"     : "/contexts/vocab#Wheel"
               },
  "@id"      : "/mybike",
  "@type"    : "Bike",
  "size"     : "L",
  "wheels"   :
               {
                  "@id"   : "/mybike/wheels",
                  "@type" : "Link",
                  "member":
                            [
                             {
                               "@id"   : "/mybike/wheels/firstwheel",
                               "@type" : "Wheel",
                               "color" : "blue"
                             },
                             {
                               "@id"   : "/mybike/wheels/secondwheel",
                               "@type" : "Wheel",
                               "color" : "white"
                             }
                            ]
               }

}

Answer 1

很高兴看到您考虑使用JSON-LD和Hydra。当然，可以在一个响应中获取所有数据。但是，您不必将集合的类型从Collection更改为Link。此外，您可能想稍微调整一下您的上下文。总而言之，您的回答看起来有点像这样：

{
  "@context": [
    "http://www.w3.org/ns/hydra/context.jsonld",
    { "@vocab": "/contexts/vocab#" }
  ],
  "@id": "/mybike",
  "@type": "Bike",
  "size": "L",
  "wheels": {
    "@id"   : "/mybike/wheels",
    "@type" : "Collection",
    "member": [
      {
        "@id"   : "/mybike/wheels/firstwheel",
        "@type" : "Wheel",
        "color" : "blue"
      },
      {
        "@id"   : "/mybike/wheels/secondwheel",
        "@type" : "Wheel",
        "color" : "white"
      }
    ]
  }
}

我在这里导入Hydra的上下文，然后覆盖默认词汇表，这意味着Hydra上下文中尚未定义的所有内容都通过将其附加到/contexts/vocab#来扩展。因此，Bike例如将扩展为/contexts/vocab#Bike。

顺便说一下。如果你使用它，你应该加入W3C Community Groupw working on Hydra。我们还有mailing list，您的所有问题都将得到解答。

可以在http://www.hydra-cg.com/#community

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使用JSON-LD和Hydra一次获取子资源的集合

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