Add otlpmetricgrpc.Expoter and otlpmetrichttp.Exporter (#4272)

* Add otlpmetricgrpc.Expoter and otlpmetrichttp.Exporter

* Update changelog

exporters/otlp/otlpmetric/otlpmetrichttp/client.go

@@ -41,17 +41,6 @@ import (
 	metricpb "go.opentelemetry.io/proto/otlp/metrics/v1"
 )
 
-// New returns an OpenTelemetry metric Exporter. The Exporter can be used with
-// a PeriodicReader to export OpenTelemetry metric data to an OTLP receiving
-// endpoint using protobufs over HTTP.
-func New(_ context.Context, opts ...Option) (metric.Exporter, error) {
-	c, err := newClient(opts...)
-	if err != nil {
-		return nil, err
-	}
-	return ominternal.New(c), nil
-}
-
 type client struct {
 	// req is cloned for every upload the client makes.
 	req         *http.Request

exporters/otlp/otlpmetric/otlpmetrichttp/exporter.go

@@ -0,0 +1,80 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otlpmetrichttp // import "go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
+
+import (
+	"context"
+
+	ominternal "go.opentelemetry.io/otel/exporters/otlp/otlpmetric/internal"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
+)
+
+// Exporter is a OpenTelemetry metric Exporter using protobufs over HTTP.
+type Exporter struct {
+	wrapped *ominternal.Exporter
+}
+
+// Temporality returns the Temporality to use for an instrument kind.
+func (e *Exporter) Temporality(k metric.InstrumentKind) metricdata.Temporality {
+	return e.wrapped.Temporality(k)
+}
+
+// Aggregation returns the Aggregation to use for an instrument kind.
+func (e *Exporter) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+	return e.wrapped.Aggregation(k)
+}
+
+// Export transforms and transmits metric data to an OTLP receiver.
+//
+// This method returns an error if called after Shutdown.
+// This method returns an error if the method is canceled by the passed context.
+func (e *Exporter) Export(ctx context.Context, rm *metricdata.ResourceMetrics) error {
+	return e.wrapped.Export(ctx, rm)
+}
+
+// ForceFlush flushes any metric data held by an exporter.
+//
+// This method returns an error if called after Shutdown.
+// This method returns an error if the method is canceled by the passed context.
+//
+// This method is safe to call concurrently.
+func (e *Exporter) ForceFlush(ctx context.Context) error {
+	return e.wrapped.ForceFlush(ctx)
+}
+
+// Shutdown flushes all metric data held by an exporter and releases any held
+// computational resources.
+//
+// This method returns an error if called after Shutdown.
+// This method returns an error if the method is canceled by the passed context.
+//
+// This method is safe to call concurrently.
+func (e *Exporter) Shutdown(ctx context.Context) error {
+	return e.wrapped.Shutdown(ctx)
+}
+
+// New returns an OpenTelemetry metric Exporter. The Exporter can be used with
+// a PeriodicReader to export OpenTelemetry metric data to an OTLP receiving
+// endpoint using protobufs over HTTP.
+func New(_ context.Context, opts ...Option) (*Exporter, error) {
+	c, err := newClient(opts...)
+	if err != nil {
+		return nil, err
+	}
+	exp := ominternal.New(c)
+	return &Exporter{exp}, nil
+}