feat(otlp-transformer)!: accept ResourceMetrics instead of ResoruceMetrics[] in metrics serializers

experimental/CHANGELOG.md

@@ -62,6 +62,9 @@ All notable changes to experimental packages in this project will be documented
     * This type is scheduled for removal in a future version of this package, please treat all exporters as `SpanExporter`, `PushMetricExporter` or `LogRecordExporter`, based on their respective type.
 * feat(otlp-grpc-exporter-base)!: collapse base classes into one [#5031](https://github.com/open-telemetry/opentelemetry-js/pull/5031)
   * `OTLPGRPCExporterNodeBase` has been removed in favor of a platform-agnostic implementation (`OTLPExporterBase` from `@opentelemetry/otlp-exporter-base`)
+* feat(otlp-transformer)!: accept `ResourceMetrics` in serializers instead of `ResourceMetrics[]`
+  * (user-facing): `ProtobufMetricsSerializer` now only accepts `ResourceMetrics` instead of `ResourceMetrics[]` to align with `PushMetricExporter` requirements
+  * (user-facing): `JsonMetricsSerializer` now only accepts `ResourceMetrics` instead of `ResourceMetrics[]` to align with `PushMetricExporter` requirements
 
 ### :rocket: (Enhancement)
 

experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterBase.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { ExportResult, getEnv } from '@opentelemetry/core';
+import { getEnv } from '@opentelemetry/core';
 import {
   AggregationTemporality,
   AggregationTemporalitySelector,
@@ -28,7 +28,10 @@ import {
   AggregationTemporalityPreference,
   OTLPMetricExporterOptions,
 } from './OTLPMetricExporterOptions';
-import { IOtlpExportDelegate } from '@opentelemetry/otlp-exporter-base';
+import {
+  IOtlpExportDelegate,
+  OTLPExporterBase,
+} from '@opentelemetry/otlp-exporter-base';
 import { diag } from '@opentelemetry/api';
 
 export const CumulativeTemporalitySelector: AggregationTemporalitySelector =
@@ -117,37 +120,24 @@ function chooseAggregationSelector(
   }
 }
 
-export class OTLPMetricExporterBase implements PushMetricExporter {
-  public _delegate: IOtlpExportDelegate<ResourceMetrics[]>;
-  private _aggregationTemporalitySelector: AggregationTemporalitySelector;
-  private _aggregationSelector: AggregationSelector;
+export class OTLPMetricExporterBase
+  extends OTLPExporterBase<ResourceMetrics>
+  implements PushMetricExporter
+{
+  private readonly _aggregationTemporalitySelector: AggregationTemporalitySelector;
+  private readonly _aggregationSelector: AggregationSelector;
 
   constructor(
-    delegate: IOtlpExportDelegate<ResourceMetrics[]>,
+    delegate: IOtlpExportDelegate<ResourceMetrics>,
     config?: OTLPMetricExporterOptions
   ) {
-    this._delegate = delegate;
+    super(delegate);
     this._aggregationSelector = chooseAggregationSelector(config);
     this._aggregationTemporalitySelector = chooseTemporalitySelector(
       config?.temporalityPreference
     );
   }
 
-  export(
-    metrics: ResourceMetrics,
-    resultCallback: (result: ExportResult) => void
-  ): void {
-    this._delegate.export([metrics], resultCallback);
-  }
-
-  async shutdown(): Promise<void> {
-    await this._delegate.shutdown();
-  }
-
-  forceFlush(): Promise<void> {
-    return this._delegate.forceFlush();
-  }
-
   selectAggregation(instrumentType: InstrumentType): Aggregation {
     return this._aggregationSelector(instrumentType);
   }

experimental/packages/opentelemetry-exporter-metrics-otlp-http/test/browser/index-webpack.ts

@@ -16,8 +16,5 @@
 const testsContext = require.context('../browser', true, /test$/);
 testsContext.keys().forEach(testsContext);
 
-const testsContextCommon = require.context('../common', true, /test$/);
-testsContextCommon.keys().forEach(testsContextCommon);
-
 const srcContext = require.context('.', true, /src$/);
 srcContext.keys().forEach(srcContext);

experimental/packages/otlp-transformer/src/json/serializers.ts

@@ -43,11 +43,11 @@ export const JsonTraceSerializer: ISerializer<
 };
 
 export const JsonMetricsSerializer: ISerializer<
-  ResourceMetrics[],
+  ResourceMetrics,
   IExportMetricsServiceResponse
 > = {
-  serializeRequest: (arg: ResourceMetrics[]) => {
-    const request = createExportMetricsServiceRequest(arg, {
+  serializeRequest: (arg: ResourceMetrics) => {
+    const request = createExportMetricsServiceRequest([arg], {
       useLongBits: false,
     });
     const encoder = new TextEncoder();

experimental/packages/otlp-transformer/src/protobuf/serializers.ts

@@ -68,11 +68,11 @@ export const ProtobufLogsSerializer: ISerializer<
 };
 
 export const ProtobufMetricsSerializer: ISerializer<
-  ResourceMetrics[],
+  ResourceMetrics,
   IExportMetricsServiceResponse
 > = {
-  serializeRequest: (arg: ResourceMetrics[]) => {
-    const request = createExportMetricsServiceRequest(arg);
+  serializeRequest: (arg: ResourceMetrics) => {
+    const request = createExportMetricsServiceRequest([arg]);
     return metricsRequestType.encode(request).finish();
   },
   deserializeResponse: (arg: Uint8Array) => {

experimental/packages/otlp-transformer/test/metrics.test.ts

@@ -788,11 +788,11 @@ describe('Metrics', () => {
 
   describe('ProtobufMetricsSerializer', function () {
     it('serializes an export request', () => {
-      const serialized = ProtobufMetricsSerializer.serializeRequest([
+      const serialized = ProtobufMetricsSerializer.serializeRequest(
         createResourceMetrics([
           createCounterData(10, AggregationTemporality.DELTA),
-        ]),
-      ]);
+        ])
+      );
       assert.ok(serialized, 'serialized response is undefined');
       const decoded =
         root.opentelemetry.proto.collector.metrics.v1.ExportMetricsServiceRequest.decode(
@@ -873,11 +873,11 @@ describe('Metrics', () => {
 
   describe('JsonMetricsSerializer', function () {
     it('serializes an export request', () => {
-      const serialized = JsonMetricsSerializer.serializeRequest([
+      const serialized = JsonMetricsSerializer.serializeRequest(
         createResourceMetrics([
           createCounterData(10, AggregationTemporality.DELTA),
-        ]),
-      ]);
+        ])
+      );
 
       const decoder = new TextDecoder();
       const expected = {