Creating a single API entrypoint

[baddlan]

The Api-platform REST Admin makes a few requests to gather the services metadata before building its interface including the navigation
menu. It expects the root URL to return a basic list of services with an Entrypoint context.

http://api.ds.ca/

{
  "@context": "/contexts/Entrypoint",
  "@id": "/",
  "@type": "Entrypoint",
  "case": "/cases"
}

The Entrypoint context itself is called to fetch the URL of the JSON-LD Docs.

http://api.ds.ca/contexts/Entrypoint

{
  "@context": {
    "@vocab": "http://api.ds.ca/docs.jsonld#",
    "hydra": "http://www.w3.org/ns/hydra/core#",
    "case": {
      "@id": "Entrypoint/case",
      "@type": "@id"
    }
  }
}

The JSON-LD Docs file describes, in details, all the entrypoints that will be listed in the navigation
as well as the properties and operations of the microservices.

http://api.ds.ca/docs.jsonld

{
  "@context": {
    "@vocab": "http://api.ds.ca/docs.jsonld#",
    "hydra": "http://www.w3.org/ns/hydra/core#",
    "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
    "rdfs": "http://www.w3.org/2000/01/rdf-schema#",
    "xmls": "http://www.w3.org/2001/XMLSchema#",
    "owl": "http://www.w3.org/2002/07/owl#",
    "domain": {
      "@id": "rdfs:domain",
      "@type": "@id"
    },
    "range": {
      "@id": "rdfs:range",
      "@type": "@id"
    },
    "subClassOf": {
      "@id": "rdfs:subClassOf",
      "@type": "@id"
    },
    "expects": {
      "@id": "hydra:expects",
      "@type": "@id"
    },
    "returns": {
      "@id": "hydra:returns",
      "@type": "@id"
    }
  },
  "@id": "/docs.jsonld",
  "hydra:title": "Cases",
  "hydra:description": "The DigitalState Cases Api",
  "hydra:entrypoint": "/",
  "hydra:supportedClass": [
    {
      "@id": "#Case",
      "@type": "hydra:Class",
      "rdfs:label": "Case",
      "hydra:title": "Case",
      "hydra:supportedProperty": [
        {
          "@type": "hydra:SupportedProperty",
          "hydra:property": {
            "@id": "#Case/title",
            "@type": "rdf:Property",
            "rdfs:label": "title",
            "domain": "#Case",
            "range": "xmls:string"
          },
          "hydra:title": "title",
          "hydra:required": true,
          "hydra:readable": true,
          "hydra:writable": true
        }
      ],
      "hydra:supportedOperation": [
        {
          "@type": "hydra:Operation",
          "hydra:method": "GET",
          "hydra:title": "Retrieves Case resource.",
          "rdfs:label": "Retrieves Case resource.",
          "returns": "#Case"
        },
        {
          "@type": "hydra:ReplaceResourceOperation",
          "expects": "#Case",
          "hydra:method": "PUT",
          "hydra:title": "Replaces the Case resource.",
          "rdfs:label": "Replaces the Case resource.",
          "returns": "#Case"
        },
        {
          "@type": "hydra:Operation",
          "hydra:method": "DELETE",
          "hydra:title": "Deletes the Case resource.",
          "rdfs:label": "Deletes the Case resource.",
          "returns": "owl:Nothing"
        }
      ],
      "hydra:description": "Class CaseEntity"
    },
    {
      "@id": "#Entrypoint",
      "@type": "hydra:Class",
      "hydra:title": "The API entrypoint",
      "hydra:supportedProperty": [
        {
          "@type": "hydra:SupportedProperty",
          "hydra:property": {
            "@id": "#Entrypoint/case",
            "@type": "hydra:Link",
            "domain": "#Entrypoint",
            "rdfs:label": "The collection of Case resources",
            "range": "hydra:PagedCollection",
            "hydra:supportedOperation": [
              {
                "@type": "hydra:Operation",
                "hydra:method": "GET",
                "hydra:title": "Retrieves the collection of Case resources.",
                "rdfs:label": "Retrieves the collection of Case resources.",
                "returns": "hydra:PagedCollection"
              },
              {
                "@type": "hydra:CreateResourceOperation",
                "expects": "#Case",
                "hydra:method": "POST",
                "hydra:title": "Creates a Case resource.",
                "rdfs:label": "Creates a Case resource.",
                "returns": "#Case"
              }
            ]
          },
          "hydra:title": "The collection of Case resources",
          "hydra:readable": true,
          "hydra:writable": false
        }
      ],
      "hydra:supportedOperation": {
        "@type": "hydra:Operation",
        "hydra:method": "GET",
        "rdfs:label": "The API entrypoint.",
        "returns": "#EntryPoint"
      }
    },
    {
      "@id": "#ConstraintViolation",
      "@type": "hydra:Class",
      "hydra:title": "A constraint violation",
      "hydra:supportedProperty": [
        {
          "@type": "hydra:SupportedProperty",
          "hydra:property": {
            "@id": "#ConstraintViolation/propertyPath",
            "@type": "rdf:Property",
            "rdfs:label": "propertyPath",
            "domain": "#ConstraintViolation",
            "range": "xmls:string"
          },
          "hydra:title": "propertyPath",
          "hydra:description": "The property path of the violation",
          "hydra:readable": true,
          "hydra:writable": false
        },
        {
          "@type": "hydra:SupportedProperty",
          "hydra:property": {
            "@id": "#ConstraintViolation/message",
            "@type": "rdf:Property",
            "rdfs:label": "message",
            "domain": "#ConstraintViolation",
            "range": "xmls:string"
          },
          "hydra:title": "message",
          "hydra:description": "The message associated with the violation",
          "hydra:readable": true,
          "hydra:writable": false
        }
      ]
    },
    {
      "@id": "#ConstraintViolationList",
      "@type": "hydra:Class",
      "subClassOf": "hydra:Error",
      "hydra:title": "A constraint violation list",
      "hydra:supportedProperty": [
        {
          "@type": "hydra:SupportedProperty",
          "hydra:property": {
            "@id": "#ConstraintViolationList/violations",
            "@type": "rdf:Property",
            "rdfs:label": "violations",
            "domain": "#ConstraintViolationList",
            "range": "#ConstraintViolation"
          },
          "hydra:title": "violations",
          "hydra:description": "The violations",
          "hydra:readable": true,
          "hydra:writable": false
        }
      ]
    }
  ]
}

We need to dynamically merge the JSON output of each of those calls by inspecting the output of their counterparts in
each microservice

• Setup a Docker container with a NginX and PHP. Make sure NginX can read ENV variables in its config file.
  See https://github.com/openresty/docker-openresty
• The URLs of the microservies are passed to the container in an ENV variable.
• In NginX, create aliases to /, /docs.jsonld and contexts/Entrypoint so they refer to PHP scripts.
• Create PHP script(s) to read the microservices URLs from the ENV variable and then fetch the JSON-LD output of the
  URLs mentioned above from each microservice before combining it all together.