feat(metadata): implement GET Units of Measure API

cmd/core-metadata/res/uom.toml

@@ -1,9 +1,8 @@
-[Uom]
 Source="reference to source for all UoM if not specified below"
-  [Uom.Units]
-    [Uom.Units.temperature]
-    Source="www.weather.com"
-    Values=["C","F","K"]
-    [Uom.Units.weights]
-    Source="www.usa.gov/federal-agencies/weights-and-measures-division"
-    Values=["lbs","ounces","kilos","grams"]
+[Units]
+  [Units.temperature]
+  Source="www.weather.com"
+  Values=["C","F","K"]
+  [Units.weights]
+  Source="www.usa.gov/federal-agencies/weights-and-measures-division"
+  Values=["lbs","ounces","kilos","grams"]

go.mod

@@ -3,7 +3,7 @@ module github.com/edgexfoundry/edgex-go
 require (
 	bitbucket.org/bertimus9/systemstat v0.0.0-20180207000608-0eeff89b0690
 	github.com/edgexfoundry/go-mod-bootstrap/v2 v2.3.0-dev.12
-	github.com/edgexfoundry/go-mod-core-contracts/v2 v2.3.0-dev.14
+	github.com/edgexfoundry/go-mod-core-contracts/v2 v2.3.0-dev.15
 	github.com/edgexfoundry/go-mod-messaging/v2 v2.3.0-dev.13
 	github.com/edgexfoundry/go-mod-registry/v2 v2.2.0
 	github.com/edgexfoundry/go-mod-secrets/v2 v2.3.0-dev.5

go.sum

@@ -36,8 +36,8 @@ github.com/edgexfoundry/go-mod-bootstrap/v2 v2.3.0-dev.12 h1:bVTjv56lGmMpr6eECOA
 github.com/edgexfoundry/go-mod-bootstrap/v2 v2.3.0-dev.12/go.mod h1:h+vCqw+fw9GN+c/ZMDKW6Ik08uL/4mMJjqVIGepmoSU=
 github.com/edgexfoundry/go-mod-configuration/v2 v2.2.0 h1:AZeaAPJM5X93ITFgwbwluYDtYEJ7tkCMSlj35GwfLLU=
 github.com/edgexfoundry/go-mod-configuration/v2 v2.2.0/go.mod h1:YP17JhMnXTitowXE13QJwFaKo0oc03iyoKLjWAYl4FE=
-github.com/edgexfoundry/go-mod-core-contracts/v2 v2.3.0-dev.14 h1:dA5YAbVHBzzD3Qi7qc9Hyqnp174zyIEhv6PtDiSJHsA=
-github.com/edgexfoundry/go-mod-core-contracts/v2 v2.3.0-dev.14/go.mod h1:YdJ0iBWad86sgOs6am01mE3IAX6d22H08f/enVho4TU=
+github.com/edgexfoundry/go-mod-core-contracts/v2 v2.3.0-dev.15 h1:nDEOf1TXpnU0fx/aKWnJE8z49OQ2AzjnOdMaoZRLzh4=
+github.com/edgexfoundry/go-mod-core-contracts/v2 v2.3.0-dev.15/go.mod h1:YdJ0iBWad86sgOs6am01mE3IAX6d22H08f/enVho4TU=
 github.com/edgexfoundry/go-mod-messaging/v2 v2.3.0-dev.13 h1:Z7bpS0HK9fdKdAb4r264Ds1nnl1yfRQk7cJMTeh6tl4=
 github.com/edgexfoundry/go-mod-messaging/v2 v2.3.0-dev.13/go.mod h1:yLJ9EK4Feg409FDr0oP87LbaRLyOSGJk/ikaIfEDKcI=
 github.com/edgexfoundry/go-mod-registry/v2 v2.2.0 h1:dk9ul1t7INAiyZXeu/GrpinFE3qOekdy8uZOqEGgIiE=

internal/core/metadata/controller/http/uom.go

@@ -0,0 +1,46 @@
+//
+// Copyright (C) 2022 IOTech Ltd
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package http
+
+import (
+	"net/http"
+
+	bootstrapContainer "github.com/edgexfoundry/go-mod-bootstrap/v2/bootstrap/container"
+	"github.com/edgexfoundry/go-mod-bootstrap/v2/di"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/common"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/dtos/responses"
+
+	"github.com/edgexfoundry/edgex-go/internal/core/metadata/container"
+	"github.com/edgexfoundry/edgex-go/internal/pkg"
+	"github.com/edgexfoundry/edgex-go/internal/pkg/utils"
+)
+
+type UnitOfMeasureController struct {
+	dic *di.Container
+}
+
+func NewUnitOfMeasureController(dic *di.Container) *UnitOfMeasureController {
+	return &UnitOfMeasureController{
+		dic: dic,
+	}
+}
+
+func (uc *UnitOfMeasureController) UnitsOfMeasure(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	u := container.UnitsOfMeasureFrom(uc.dic.Get)
+	lc := bootstrapContainer.LoggingClientFrom(uc.dic.Get)
+
+	response := responses.NewUnitsOfMeasureResponse("", "", http.StatusOK, u)
+
+	utils.WriteHttpHeader(w, ctx, http.StatusOK)
+
+	switch r.Header.Get(common.Accept) {
+	case common.ContentTypeTOML:
+		pkg.EncodeAndWriteTomlResponse(u, w, lc)
+	default:
+		pkg.EncodeAndWriteResponse(response, w, lc)
+	}
+}

internal/core/metadata/controller/http/uom_test.go

@@ -0,0 +1,86 @@
+//
+// Copyright (C) 2022 IOTech Ltd
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package http
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/edgexfoundry/go-mod-bootstrap/v2/di"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/common"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/dtos/responses"
+	"github.com/pelletier/go-toml"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/edgexfoundry/edgex-go/internal/core/metadata/container"
+	"github.com/edgexfoundry/edgex-go/internal/core/metadata/uom"
+)
+
+func TestUnitOfMeasureController_UnitsOfMeasure(t *testing.T) {
+	testUoM := uom.UnitsOfMeasureImpl{
+		Source: "test global source",
+		Units: map[string]uom.Unit{
+			"unit1": uom.Unit{
+				Source: "test unit source",
+				Values: []string{"v1", "v2", "v3"},
+			},
+		},
+	}
+	dic := mockDic()
+	dic.Update(di.ServiceConstructorMap{
+		container.UnitsOfMeasureInterfaceName: func(get di.Get) interface{} {
+			return &testUoM
+		},
+	})
+
+	controller := NewUnitOfMeasureController(dic)
+	assert.NotNil(t, controller)
+
+	tests := []struct {
+		name             string
+		accept           string
+		expectedResponse any
+	}{
+		{"valid - json response", common.ContentTypeJSON, responses.NewUnitsOfMeasureResponse("", "", http.StatusOK, testUoM)},
+		{"valid - toml response", common.ContentTypeTOML, testUoM},
+	}
+
+	for _, testCase := range tests {
+		t.Run(testCase.name, func(t *testing.T) {
+			req, err := http.NewRequest(http.MethodGet, common.ApiUnitsOfMeasureRoute, http.NoBody)
+			req.Header.Set(common.Accept, testCase.accept)
+			require.NoError(t, err)
+
+			recorder := httptest.NewRecorder()
+			handler := http.HandlerFunc(controller.UnitsOfMeasure)
+			handler.ServeHTTP(recorder, req)
+
+			assert.Equal(t, http.StatusOK, recorder.Result().StatusCode, "HTTP status code not as expected")
+			if testCase.accept == common.ContentTypeJSON {
+				expectedBytes, err := json.Marshal(testCase.expectedResponse)
+				require.NoError(t, err)
+				assert.JSONEq(t, recorder.Body.String(), string(expectedBytes), "JSON response not as expected")
+
+				actualResponse := responses.UnitsOfMeasureResponse{}
+				err = json.Unmarshal(recorder.Body.Bytes(), &actualResponse)
+				require.NoError(t, err)
+
+				assert.Equal(t, common.ApiVersion, actualResponse.ApiVersion, "Api Version not as expected")
+				assert.Equal(t, http.StatusOK, actualResponse.StatusCode, "BaseResponse status code not as expected")
+				assert.Empty(t, actualResponse.Message, "Message should be empty when it is successful")
+			} else {
+				actualResponse := uom.UnitsOfMeasureImpl{}
+				err = toml.Unmarshal(recorder.Body.Bytes(), &actualResponse)
+				require.NoError(t, err)
+
+				assert.Equal(t, actualResponse, testCase.expectedResponse, "TOML response not as expected")
+			}
+		})
+	}
+}

internal/core/metadata/router.go

@@ -27,6 +27,10 @@ func LoadRestRoutes(r *mux.Router, dic *di.Container, serviceName string) {
 	r.HandleFunc(common.ApiConfigRoute, cc.Config).Methods(http.MethodGet)
 	r.HandleFunc(common.ApiMetricsRoute, cc.Metrics).Methods(http.MethodGet)
 
+	// Units of Measure
+	uc := metadataController.NewUnitOfMeasureController(dic)
+	r.HandleFunc(common.ApiUnitsOfMeasureRoute, uc.UnitsOfMeasure).Methods(http.MethodGet)
+
 	// Device Profile
 	dc := metadataController.NewDeviceProfileController(dic)
 	r.HandleFunc(common.ApiDeviceProfileRoute, dc.AddDeviceProfile).Methods(http.MethodPost)

internal/core/metadata/uom/uom.go

@@ -6,25 +6,21 @@
 package uom
 
 type UnitsOfMeasureImpl struct {
-	Uom ConfigurationStruct
-}
-
-type ConfigurationStruct struct {
-	Source string
-	Units  map[string]Unit
+	Source string          `json:"source,omitempty"`
+	Units  map[string]Unit `json:"units,omitempty"`
 }
 
 type Unit struct {
-	Source string
-	Values []string
+	Source string   `json:"source,omitempty"`
+	Values []string `json:"values,omitempty"`
 }
 
 func (u *UnitsOfMeasureImpl) Validate(unit string) bool {
-	if unit == "" || len(u.Uom.Units) == 0 {
+	if unit == "" || len(u.Units) == 0 {
 		return true
 	}
 
-	for _, units := range u.Uom.Units {
+	for _, units := range u.Units {
 		for _, v := range units.Values {
 			if unit == v {
 				return true

internal/pkg/encoding.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/edgexfoundry/go-mod-core-contracts/v2/clients/logger"
 	"github.com/edgexfoundry/go-mod-core-contracts/v2/common"
+	"github.com/pelletier/go-toml"
 )
 
 func EncodeAndWriteResponse(i interface{}, w http.ResponseWriter, LoggingClient logger.LoggingClient) {
@@ -29,7 +30,20 @@ func EncodeAndWriteResponse(i interface{}, w http.ResponseWriter, LoggingClient
 	// Problems encoding
 	if err != nil {
 		LoggingClient.Error("Error encoding the data: " + err.Error())
-		http.Error(w, err.Error(), http.StatusBadRequest)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+}
+
+func EncodeAndWriteTomlResponse(i interface{}, w http.ResponseWriter, lc logger.LoggingClient) {
+	w.Header().Set(common.ContentType, common.ContentTypeTOML)
+
+	enc := toml.NewEncoder(w)
+	err := enc.Encode(i)
+	// Problems encoding
+	if err != nil {
+		lc.Error("Error encoding the data: " + err.Error())
+		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 }

openapi/v2/core-metadata.yaml

@@ -1076,6 +1076,36 @@ components:
         serviceName:
           description: "Outputs the name of the service the response is from"
           type: string
+    Unit:
+      description: "express magnitudes of a physical quantity"
+      type: object
+      properties:
+        source:
+          type: string
+          description: "helps provide the location of documentation about the origins and details of the units specified"
+        values:
+          type: array
+          items:
+            type: string
+          description: "a list of arbitrary unit representation to be interpreted by the EdgeX data provider/consumer"
+    UnitsOfMeasure:
+      description: "Units of Measure definition"
+      type: object
+      properties:
+        source:
+          type: string
+          description: "top level location of documentation about the origins and details of the units specified"
+        units:
+          type: object
+          additionalProperties:
+            $ref: '#/components/schemas/Unit'
+    UnitsOfMeasureResponse:
+      allOf:
+        - $ref: '#/components/schemas/BaseResponse'
+      type: object
+      properties:
+        uom:
+          $ref: '#/components/schemas/UnitsOfMeasure'
   parameters:
     offsetParam:
       in: query
@@ -1103,6 +1133,15 @@ components:
         type: string
         format: uuid
       example: "14a42ea6-c394-41c3-8bcd-a29b9f5e6835"
+    acceptHeader:
+      in: header
+      name: Accept
+      description: "indicates which content types, expressed as MIME types, the client is able to understand"
+      schema:
+        type: string
+        enum:
+          - application/json
+          - application/toml
     labelsParam:
       in: query
       name: labels
@@ -1481,6 +1520,26 @@ components:
             profileName: "device-simple"
             serviceName: "device-simple"
             adminState: "UNLOCKED"
+    UnitsOfMeasureResponseExample:
+      value:
+        apiVersion: "v2"
+        statusCode: 200
+        uom:
+          source: "reference to source for all UoM if not specified below"
+          units:
+            "temperature":
+              source: "www.weather.com"
+              value:
+                - "C"
+                - "F"
+                - "K"
+            "weights":
+              source: "www.usa.gov/federal-agencies/weights-and-measures-division"
+              value:
+                - "lbs"
+                - "ounces"
+                - "kilos"
+                - "grams"
 paths:
   /device:
     parameters:
@@ -3767,6 +3826,39 @@ paths:
               examples:
                 500Example:
                   $ref: '#/components/examples/500Example'
+  /uom:
+    get:
+      summary: "Returns the Units of Measure definition"
+      parameters:
+        - $ref: '#/components/parameters/acceptHeader'
+      responses:
+        '200':
+          description: "OK"
+          headers:
+            X-Correlation-ID:
+              $ref: '#/components/headers/correlatedResponseHeader'
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/UnitsOfMeasureResponse'
+              examples:
+                UnitsOfMeasureResponse:
+                  $ref: '#/components/examples/UnitsOfMeasureResponseExample'
+            application/toml:
+              schema:
+                $ref: '#/components/schemas/UnitsOfMeasure'
+        '500':
+          description: "Internal Server Error"
+          headers:
+            X-Correlation-ID:
+              $ref: '#/components/headers/correlatedResponseHeader'
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+              examples:
+                500Example:
+                  $ref: '#/components/examples/500Example'
   /config:
     get:
       summary: "Returns the current configuration of the service."