Menene HATEOAS da Richardson Maturity Model?

Question

IT Interview Practice · Accepted Answer

**Richardson Maturity Model (RMM)** yana ba da maki kan yadda API yake "RESTful" a matakai huɗu, kuma **HATEOAS** shi ne matakin sama — ƙuntatawar da yawancin mutane ke tsallakewa.

## Matakai huɗu

```text
Level 0 — "The Swamp of POX": one URI, one method (RPC over HTTP).
          POST /api  { "action": "getUser", "id": 42 }
Level 1 — Resources: many URIs, but still one verb.
          POST /users/42  ,  POST /users/42/delete
Level 2 — HTTP Verbs: proper methods + status codes (where most "REST" APIs live).
          GET /users/42 → 200 ,  DELETE /users/42 → 204
Level 3 — Hypermedia Controls (HATEOAS): responses link to what you can do next.
```

Yawancin APIs na "REST" a production suna **Level 2** — resources, methods, da status codes daidai. Yawanci hakan ya isa, kuma manufa ce mai ma'ana sosai.

## HATEOAS (Level 3)

**HATEOAS** = *Hypermedia As The Engine Of Application State*. Manufar: response yana haɗa **links** da ke gaya wa client waɗanne ayyuka ke akwai na gaba, don haka client yana kewaya API ta bin links maimakon hardcode ɗin URLs — kamar mutum yana bin links a shafin web maimakon haddar kowane URL.

```http
GET /orders/1001 HTTP/1.1
```
```http
HTTP/1.1 200 OK
Content-Type: application/json

{
  "id": 1001,
  "status": "pending",
  "total": 250,
  "_links": {
    "self":   { "href": "/orders/1001" },
    "pay":    { "href": "/orders/1001/payment", "method": "POST" },
    "cancel": { "href": "/orders/1001/cancel",  "method": "POST" }
  }
}
```

Saboda order yana `pending`, server yana bayar da links na `pay` da `cancel`. Da zarar an biya, waɗannan links suna ɓacewa kuma link na `refund` zai iya bayyana — **server ne ke jagorantar canjin yanayi (state transitions)**, kuma client kawai yana bin duk links ɗin da aka ba shi.

## Me ya sa yake da wuya

Alkawari shi ne decoupling: clients ba sa hardcode ɗin URLs, don haka server na iya sake tsara su cikin 'yanci. A aikace yawancin clients suna hardcode duk da haka, HATEOAS yana ƙara rikitarwa ta gaske, kuma tsare-tsare ba su taɓa zama ma'aunin gama gari ba (HAL, JSON:API, Siren duk suna gasa). Amfanin ba safai yake cancanta farashin ba.

## Me ya sa yake da muhimmanci

Wannan tambaya ce ta gargajiya ta matakin senior domin tana rarrabe mutanen da suka **fahimci REST kamar yadda aka ayyana shi da farko** da waɗanda ke amfani da "REST" a hankali don nufin "JSON a kan HTTP". Fahimtar da take da daraja ba karanta matakai huɗu ba ce — hankali ne na cewa **Level 2 shi ne wurin dadi mai amfani** yayin da ka sani cewa REST na gaske (ma'anar Fielding) *yana bukatar* HATEOAS, da iya bayyana *dalilin da ya sa masana'antu galibi ke yin watsi da shi*: fa'idar decoupling gaskiya ce amma ba safai ake samun ta ba domin clients suna hardcode ɗin URLs ko da yaya, kuma ƙarin rikitarwa tare da tsare-tsaren hypermedia masu gasa ba sa biya ga APIs na yau da kullum. Nuna ka san menene HATEOAS *shi*, iya nuna misali na zahiri na links da yanayi ke jagoranta, da iya jayayya cikin gaskiya game da farashi/fa'ida — maimakon nacewa da ƙa'ida cewa kowane API dole ya zama Level 3 — shi ne ainihin hankali mai daidaituwa, bisa gogewa da masu hira ke bincike.

Matakai huɗu

HATEOAS (Level 3)

Me ya sa yake da wuya

Me ya sa yake da muhimmanci

Tambayoyi masu alaƙa