diff --git a/packages/opentelemetry-api/src/api/propagation.ts b/packages/opentelemetry-api/src/api/propagation.ts
index 60a950e4d6..0e62ad76eb 100644
--- a/packages/opentelemetry-api/src/api/propagation.ts
+++ b/packages/opentelemetry-api/src/api/propagation.ts
@@ -15,9 +15,10 @@
  */
 
 import { Context } from '@opentelemetry/scope-base';
-import { Carrier } from '../context/propagation/carrier';
+import { defaultGetter, GetterFunction } from '../context/propagation/getter';
 import { HttpTextFormat } from '../context/propagation/HttpTextFormat';
 import { NOOP_HTTP_TEXT_FORMAT } from '../context/propagation/NoopHttpTextFormat';
+import { defaultSetter, SetterFunction } from '../context/propagation/setter';
 import { ContextAPI } from './context';
 
 const contextApi = ContextAPI.getInstance();
@@ -53,19 +54,29 @@ export class PropagationAPI {
    * Inject context into a carrier to be propagated inter-process
    *
    * @param carrier carrier to inject context into
+   * @param setter Function used to set values on the carrier
    * @param context Context carrying tracing data to inject. Defaults to the currently active context.
    */
-  public inject(carrier: Carrier, context = contextApi.active()): void {
-    return this._propagator.inject(context, carrier);
+  public inject<Carrier>(
+    carrier: Carrier,
+    setter: SetterFunction<Carrier> = defaultSetter,
+    context = contextApi.active()
+  ): void {
+    return this._propagator.inject(context, carrier, setter);
   }
 
   /**
    * Extract context from a carrier
    *
    * @param carrier Carrier to extract context from
+   * @param getter Function used to extract keys from a carrier
    * @param context Context which the newly created context will inherit from. Defaults to the currently active context.
    */
-  public extract(carrier: Carrier, context = contextApi.active()): Context {
-    return this._propagator.extract(context, carrier);
+  public extract<Carrier>(
+    carrier: Carrier,
+    getter: GetterFunction<Carrier> = defaultGetter,
+    context = contextApi.active()
+  ): Context {
+    return this._propagator.extract(context, carrier, getter);
   }
 }
diff --git a/packages/opentelemetry-api/src/context/propagation/HttpTextFormat.ts b/packages/opentelemetry-api/src/context/propagation/HttpTextFormat.ts
index 6e14f94868..efd1e4efab 100644
--- a/packages/opentelemetry-api/src/context/propagation/HttpTextFormat.ts
+++ b/packages/opentelemetry-api/src/context/propagation/HttpTextFormat.ts
@@ -15,7 +15,8 @@
  */
 
 import { Context } from '@opentelemetry/scope-base';
-import { Carrier } from './carrier';
+import { SetterFunction } from './setter';
+import { GetterFunction } from './getter';
 
 /**
  * Injects {@link Context} into and extracts it from carriers that travel
@@ -37,8 +38,10 @@ export interface HttpTextFormat {
    *     the wire.
    * @param carrier the carrier of propagation fields, such as http request
    *     headers.
+   * @param setter a function which accepts a carrier, key, and value, which
+   *     sets the key on the carrier to the value.
    */
-  inject(context: Context, carrier: Carrier): void;
+  inject(context: Context, carrier: unknown, setter: SetterFunction): void;
 
   /**
    * Given a {@link Context} and a carrier, extract context values from a
@@ -49,6 +52,8 @@ export interface HttpTextFormat {
    *     the wire.
    * @param carrier the carrier of propagation fields, such as http request
    *     headers.
+   * @param getter a function which accepts a carrier and a key, and returns
+   *     the value from the carrier identified by the key.
    */
-  extract(context: Context, carrier: Carrier): Context;
+  extract(context: Context, carrier: unknown, getter: GetterFunction): Context;
 }
diff --git a/packages/opentelemetry-api/src/context/propagation/NoopHttpTextFormat.ts b/packages/opentelemetry-api/src/context/propagation/NoopHttpTextFormat.ts
index 1f38729eb5..4978cc0fbc 100644
--- a/packages/opentelemetry-api/src/context/propagation/NoopHttpTextFormat.ts
+++ b/packages/opentelemetry-api/src/context/propagation/NoopHttpTextFormat.ts
@@ -15,7 +15,6 @@
  */
 
 import { Context } from '@opentelemetry/scope-base';
-import { Carrier } from './carrier';
 import { HttpTextFormat } from './HttpTextFormat';
 
 /**
@@ -23,9 +22,9 @@ import { HttpTextFormat } from './HttpTextFormat';
  */
 export class NoopHttpTextFormat implements HttpTextFormat {
   /** Noop inject function does nothing */
-  inject(context: Context, carrier: Carrier): void {}
+  inject(context: Context, carrier: unknown, setter: Function): void {}
   /** Noop extract function does nothing and returns the input context */
-  extract(context: Context, carrier: Carrier): Context {
+  extract(context: Context, carrier: unknown, getter: Function): Context {
     return context;
   }
 }
diff --git a/packages/opentelemetry-api/src/context/propagation/getter.ts b/packages/opentelemetry-api/src/context/propagation/getter.ts
new file mode 100644
index 0000000000..158bd0fdd1
--- /dev/null
+++ b/packages/opentelemetry-api/src/context/propagation/getter.ts
@@ -0,0 +1,31 @@
+/*!
+ * Copyright 2020, 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
+ *
+ *      https://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.
+ */
+
+export type GetterFunction<Carrier = any> = (
+  carrier: Carrier,
+  key: string
+) => unknown;
+
+/**
+ * Default getter which just does a simple property access. Returns
+ * undefined if the key is not set.
+ *
+ * @param carrier
+ * @param key
+ */
+export function defaultGetter(carrier: any, key: string): unknown {
+  return carrier[key];
+}
diff --git a/packages/opentelemetry-api/src/context/propagation/carrier.ts b/packages/opentelemetry-api/src/context/propagation/setter.ts
similarity index 65%
rename from packages/opentelemetry-api/src/context/propagation/carrier.ts
rename to packages/opentelemetry-api/src/context/propagation/setter.ts
index 7644ace1af..29c6abed73 100644
--- a/packages/opentelemetry-api/src/context/propagation/carrier.ts
+++ b/packages/opentelemetry-api/src/context/propagation/setter.ts
@@ -14,6 +14,18 @@
  * limitations under the License.
  */
 
-export type Carrier = {
-  [key: string]: unknown;
-};
+export type SetterFunction<Carrier = any> = (
+  carrier: Carrier,
+  key: string,
+  value: unknown
+) => void;
+
+/**
+ * Default setter which sets value via direct property access
+ *
+ * @param carrier
+ * @param key
+ */
+export function defaultSetter(carrier: any, key: string, value: unknown) {
+  carrier[key] = value;
+}
diff --git a/packages/opentelemetry-api/src/index.ts b/packages/opentelemetry-api/src/index.ts
index 2653d5af56..23f31f3ec6 100644
--- a/packages/opentelemetry-api/src/index.ts
+++ b/packages/opentelemetry-api/src/index.ts
@@ -16,8 +16,9 @@
 
 export * from './common/Logger';
 export * from './common/Time';
-export * from './context/propagation/carrier';
+export * from './context/propagation/getter';
 export * from './context/propagation/HttpTextFormat';
+export * from './context/propagation/setter';
 export * from './correlation_context/CorrelationContext';
 export * from './correlation_context/EntryValue';
 export * from './metrics/BoundInstrument';
diff --git a/packages/opentelemetry-api/test/noop-implementations/noop-tracer.test.ts b/packages/opentelemetry-api/test/noop-implementations/noop-tracer.test.ts
index fc623d2526..f1e28be91f 100644
--- a/packages/opentelemetry-api/test/noop-implementations/noop-tracer.test.ts
+++ b/packages/opentelemetry-api/test/noop-implementations/noop-tracer.test.ts
@@ -14,9 +14,11 @@
  * limitations under the License.
  */
 
+import { Context } from '@opentelemetry/scope-base';
 import * as assert from 'assert';
 import { NoopTracer, NOOP_SPAN, SpanKind } from '../../src';
-import { Context } from '@opentelemetry/scope-base';
+import { defaultGetter } from '../../src/context/propagation/getter';
+import { defaultSetter } from '../../src/context/propagation/setter';
 
 describe('NoopTracer', () => {
   it('should not crash', () => {
@@ -38,9 +40,9 @@ describe('NoopTracer', () => {
     const httpTextFormat = tracer.getHttpTextFormat();
     assert.ok(httpTextFormat);
 
-    httpTextFormat.inject(Context.ROOT_CONTEXT, {});
+    httpTextFormat.inject(Context.ROOT_CONTEXT, {}, defaultSetter);
     assert.deepStrictEqual(
-      httpTextFormat.extract(Context.ROOT_CONTEXT, {}),
+      httpTextFormat.extract(Context.ROOT_CONTEXT, {}, defaultGetter),
       Context.ROOT_CONTEXT
     );
   });
diff --git a/packages/opentelemetry-core/src/context/propagation/B3Format.ts b/packages/opentelemetry-core/src/context/propagation/B3Format.ts
index 2f2b7c9142..55681ddefe 100644
--- a/packages/opentelemetry-core/src/context/propagation/B3Format.ts
+++ b/packages/opentelemetry-core/src/context/propagation/B3Format.ts
@@ -15,9 +15,10 @@
  */
 
 import {
-  Carrier,
   Context,
+  GetterFunction,
   HttpTextFormat,
+  SetterFunction,
   TraceFlags,
 } from '@opentelemetry/api';
 import { getParentSpanContext, setExtractedSpanContext } from '../context';
@@ -42,7 +43,7 @@ function isValidSpanId(spanId: string): boolean {
  * Based on: https://github.com/openzipkin/b3-propagation
  */
 export class B3Format implements HttpTextFormat {
-  inject(context: Context, carrier: Carrier) {
+  inject(context: Context, carrier: unknown, setter: SetterFunction) {
     const spanContext = getParentSpanContext(context);
     if (!spanContext) return;
 
@@ -50,21 +51,21 @@ export class B3Format implements HttpTextFormat {
       isValidTraceId(spanContext.traceId) &&
       isValidSpanId(spanContext.spanId)
     ) {
-      carrier[X_B3_TRACE_ID] = spanContext.traceId;
-      carrier[X_B3_SPAN_ID] = spanContext.spanId;
+      setter(carrier, X_B3_TRACE_ID, spanContext.traceId);
+      setter(carrier, X_B3_SPAN_ID, spanContext.spanId);
 
       // We set the header only if there is an existing sampling decision.
       // Otherwise we will omit it => Absent.
       if (spanContext.traceFlags !== undefined) {
-        carrier[X_B3_SAMPLED] = Number(spanContext.traceFlags);
+        setter(carrier, X_B3_SAMPLED, Number(spanContext.traceFlags));
       }
     }
   }
 
-  extract(context: Context, carrier: Carrier): Context {
-    const traceIdHeader = carrier[X_B3_TRACE_ID];
-    const spanIdHeader = carrier[X_B3_SPAN_ID];
-    const sampledHeader = carrier[X_B3_SAMPLED];
+  extract(context: Context, carrier: unknown, getter: GetterFunction): Context {
+    const traceIdHeader = getter(carrier, X_B3_TRACE_ID);
+    const spanIdHeader = getter(carrier, X_B3_SPAN_ID);
+    const sampledHeader = getter(carrier, X_B3_SAMPLED);
     if (!traceIdHeader || !spanIdHeader) return context;
     const traceId = Array.isArray(traceIdHeader)
       ? traceIdHeader[0]
diff --git a/packages/opentelemetry-core/src/context/propagation/HttpTraceContext.ts b/packages/opentelemetry-core/src/context/propagation/HttpTraceContext.ts
index c1495579f1..12899eabf9 100644
--- a/packages/opentelemetry-core/src/context/propagation/HttpTraceContext.ts
+++ b/packages/opentelemetry-core/src/context/propagation/HttpTraceContext.ts
@@ -15,9 +15,10 @@
  */
 
 import {
-  Carrier,
   Context,
+  GetterFunction,
   HttpTextFormat,
+  SetterFunction,
   SpanContext,
   TraceFlags,
 } from '@opentelemetry/api';
@@ -63,7 +64,7 @@ export function parseTraceParent(traceParent: string): SpanContext | null {
  * https://www.w3.org/TR/trace-context/
  */
 export class HttpTraceContext implements HttpTextFormat {
-  inject(context: Context, carrier: Carrier) {
+  inject(context: Context, carrier: unknown, setter: SetterFunction) {
     const spanContext = getParentSpanContext(context);
     if (!spanContext) return;
 
@@ -71,14 +72,14 @@ export class HttpTraceContext implements HttpTextFormat {
       spanContext.spanId
     }-0${Number(spanContext.traceFlags || TraceFlags.UNSAMPLED).toString(16)}`;
 
-    carrier[TRACE_PARENT_HEADER] = traceParent;
+    setter(carrier, TRACE_PARENT_HEADER, traceParent);
     if (spanContext.traceState) {
-      carrier[TRACE_STATE_HEADER] = spanContext.traceState.serialize();
+      setter(carrier, TRACE_STATE_HEADER, spanContext.traceState.serialize());
     }
   }
 
-  extract(context: Context, carrier: Carrier): Context {
-    const traceParentHeader = carrier[TRACE_PARENT_HEADER];
+  extract(context: Context, carrier: unknown, getter: GetterFunction): Context {
+    const traceParentHeader = getter(carrier, TRACE_PARENT_HEADER);
     if (!traceParentHeader) return context;
     const traceParent = Array.isArray(traceParentHeader)
       ? traceParentHeader[0]
@@ -88,7 +89,7 @@ export class HttpTraceContext implements HttpTextFormat {
 
     spanContext.isRemote = true;
 
-    const traceStateHeader = carrier[TRACE_STATE_HEADER];
+    const traceStateHeader = getter(carrier, TRACE_STATE_HEADER);
     if (traceStateHeader) {
       // If more than one `tracestate` header is found, we merge them into a
       // single header.
diff --git a/packages/opentelemetry-core/src/context/propagation/composite.ts b/packages/opentelemetry-core/src/context/propagation/composite.ts
index c1a2906658..0979021fb6 100644
--- a/packages/opentelemetry-core/src/context/propagation/composite.ts
+++ b/packages/opentelemetry-core/src/context/propagation/composite.ts
@@ -14,7 +14,13 @@
  * limitations under the License.
  */
 
-import { Carrier, Context, HttpTextFormat, Logger } from '@opentelemetry/api';
+import {
+  Context,
+  GetterFunction,
+  HttpTextFormat,
+  Logger,
+  SetterFunction,
+} from '@opentelemetry/api';
 import { NoopLogger } from '../../common/NoopLogger';
 import { CompositePropagatorConfig } from './types';
 
@@ -42,10 +48,10 @@ export class CompositePropagator implements HttpTextFormat {
    * @param context Context to inject
    * @param carrier Carrier into which context will be injected
    */
-  inject(context: Context, carrier: Carrier) {
+  inject(context: Context, carrier: unknown, setter: SetterFunction) {
     for (const propagator of this._propagators) {
       try {
-        propagator.inject(context, carrier);
+        propagator.inject(context, carrier, setter);
       } catch (err) {
         this._logger.warn(
           `Failed to inject with ${propagator.constructor.name}. Err: ${err.message}`
@@ -63,10 +69,10 @@ export class CompositePropagator implements HttpTextFormat {
    * @param context Context to add values to
    * @param carrier Carrier from which to extract context
    */
-  extract(context: Context, carrier: Carrier): Context {
+  extract(context: Context, carrier: unknown, getter: GetterFunction): Context {
     return this._propagators.reduce((ctx, propagator) => {
       try {
-        return propagator.extract(ctx, carrier);
+        return propagator.extract(ctx, carrier, getter);
       } catch (err) {
         this._logger.warn(
           `Failed to inject with ${propagator.constructor.name}. Err: ${err.message}`
diff --git a/packages/opentelemetry-core/test/context/B3Format.test.ts b/packages/opentelemetry-core/test/context/B3Format.test.ts
index df7a1e6162..22c327819d 100644
--- a/packages/opentelemetry-core/test/context/B3Format.test.ts
+++ b/packages/opentelemetry-core/test/context/B3Format.test.ts
@@ -14,13 +14,18 @@
  * limitations under the License.
  */
 
-import { SpanContext, TraceFlags } from '@opentelemetry/api';
+import {
+  defaultGetter,
+  defaultSetter,
+  SpanContext,
+  TraceFlags,
+} from '@opentelemetry/api';
+import { Context } from '@opentelemetry/scope-base';
 import * as assert from 'assert';
 import {
-  setExtractedSpanContext,
   getExtractedSpanContext,
+  setExtractedSpanContext,
 } from '../../src/context/context';
-import { Context } from '@opentelemetry/scope-base';
 import {
   B3Format,
   X_B3_SAMPLED,
@@ -47,7 +52,8 @@ describe('B3Format', () => {
 
       b3Format.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, spanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(
         carrier[X_B3_TRACE_ID],
@@ -68,7 +74,8 @@ describe('B3Format', () => {
 
       b3Format.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, spanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(
         carrier[X_B3_TRACE_ID],
@@ -85,7 +92,8 @@ describe('B3Format', () => {
       };
       b3Format.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, emptySpanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(carrier[X_B3_TRACE_ID], undefined);
       assert.deepStrictEqual(carrier[X_B3_SPAN_ID], undefined);
@@ -99,7 +107,8 @@ describe('B3Format', () => {
 
       b3Format.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, spanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(
         carrier[X_B3_TRACE_ID],
@@ -115,7 +124,7 @@ describe('B3Format', () => {
       carrier[X_B3_TRACE_ID] = '0af7651916cd43dd8448eb211c80319c';
       carrier[X_B3_SPAN_ID] = 'b7ad6b7169203331';
       const extractedSpanContext = getExtractedSpanContext(
-        b3Format.extract(Context.ROOT_CONTEXT, carrier)
+        b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -131,7 +140,7 @@ describe('B3Format', () => {
       carrier[X_B3_SPAN_ID] = 'b7ad6b7169203331';
       carrier[X_B3_SAMPLED] = '1';
       const extractedSpanContext = getExtractedSpanContext(
-        b3Format.extract(Context.ROOT_CONTEXT, carrier)
+        b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -147,7 +156,7 @@ describe('B3Format', () => {
       carrier[X_B3_SPAN_ID] = 'b7ad6b7169203331';
       carrier[X_B3_SAMPLED] = true;
       const extractedSpanContext = getExtractedSpanContext(
-        b3Format.extract(Context.ROOT_CONTEXT, carrier)
+        b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -163,7 +172,7 @@ describe('B3Format', () => {
       carrier[X_B3_SPAN_ID] = 'b7ad6b7169203331';
       carrier[X_B3_SAMPLED] = false;
       const extractedSpanContext = getExtractedSpanContext(
-        b3Format.extract(Context.ROOT_CONTEXT, carrier)
+        b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -179,7 +188,7 @@ describe('B3Format', () => {
       carrier[X_B3_SPAN_ID] = undefined;
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          b3Format.extract(Context.ROOT_CONTEXT, carrier)
+          b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         ),
         undefined
       );
@@ -190,7 +199,7 @@ describe('B3Format', () => {
       carrier[X_B3_SPAN_ID] = undefined;
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          b3Format.extract(Context.ROOT_CONTEXT, carrier)
+          b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         ),
         undefined
       );
@@ -199,7 +208,7 @@ describe('B3Format', () => {
     it('returns undefined if b3 header is missing', () => {
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          b3Format.extract(Context.ROOT_CONTEXT, carrier)
+          b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         ),
         undefined
       );
@@ -209,7 +218,7 @@ describe('B3Format', () => {
       carrier[X_B3_TRACE_ID] = 'invalid!';
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          b3Format.extract(Context.ROOT_CONTEXT, carrier)
+          b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         ),
         undefined
       );
@@ -220,7 +229,7 @@ describe('B3Format', () => {
       carrier[X_B3_SPAN_ID] = 'b7ad6b7169203331';
       carrier[X_B3_SAMPLED] = '01';
       const extractedSpanContext = getExtractedSpanContext(
-        b3Format.extract(Context.ROOT_CONTEXT, carrier)
+        b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
@@ -271,7 +280,7 @@ describe('B3Format', () => {
         carrier[X_B3_TRACE_ID] = testCases[testCase];
 
         const extractedSpanContext = getExtractedSpanContext(
-          b3Format.extract(Context.ROOT_CONTEXT, carrier)
+          b3Format.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         );
         assert.deepStrictEqual(extractedSpanContext, undefined, testCase);
       });
diff --git a/packages/opentelemetry-core/test/context/HttpTraceContext.test.ts b/packages/opentelemetry-core/test/context/HttpTraceContext.test.ts
index bc74b8d682..778ea9029c 100644
--- a/packages/opentelemetry-core/test/context/HttpTraceContext.test.ts
+++ b/packages/opentelemetry-core/test/context/HttpTraceContext.test.ts
@@ -14,7 +14,12 @@
  * limitations under the License.
  */
 
-import { SpanContext, TraceFlags } from '@opentelemetry/api';
+import {
+  defaultGetter,
+  defaultSetter,
+  SpanContext,
+  TraceFlags,
+} from '@opentelemetry/api';
 import { Context } from '@opentelemetry/scope-base';
 import * as assert from 'assert';
 import {
@@ -46,7 +51,8 @@ describe('HttpTraceContext', () => {
 
       httpTraceContext.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, spanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(
         carrier[TRACE_PARENT_HEADER],
@@ -65,7 +71,8 @@ describe('HttpTraceContext', () => {
 
       httpTraceContext.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, spanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(
         carrier[TRACE_PARENT_HEADER],
@@ -80,7 +87,7 @@ describe('HttpTraceContext', () => {
       carrier[TRACE_PARENT_HEADER] =
         '00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01';
       const extractedSpanContext = getExtractedSpanContext(
-        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier)
+        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -94,7 +101,7 @@ describe('HttpTraceContext', () => {
     it('returns null if traceparent header is missing', () => {
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          httpTraceContext.extract(Context.ROOT_CONTEXT, carrier)
+          httpTraceContext.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         ),
         undefined
       );
@@ -104,7 +111,7 @@ describe('HttpTraceContext', () => {
       carrier[TRACE_PARENT_HEADER] = 'invalid!';
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          httpTraceContext.extract(Context.ROOT_CONTEXT, carrier)
+          httpTraceContext.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         ),
         undefined
       );
@@ -115,7 +122,7 @@ describe('HttpTraceContext', () => {
         '00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01',
       ];
       const extractedSpanContext = getExtractedSpanContext(
-        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier)
+        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
@@ -130,7 +137,7 @@ describe('HttpTraceContext', () => {
         '00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01';
       carrier[TRACE_STATE_HEADER] = 'foo=bar,baz=qux';
       const extractedSpanContext = getExtractedSpanContext(
-        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier)
+        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       assert.deepStrictEqual(
@@ -148,7 +155,7 @@ describe('HttpTraceContext', () => {
         '00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01';
       carrier[TRACE_STATE_HEADER] = ['foo=bar,baz=qux', 'quux=quuz'];
       const extractedSpanContext = getExtractedSpanContext(
-        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier)
+        httpTraceContext.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
@@ -200,7 +207,7 @@ describe('HttpTraceContext', () => {
         carrier[TRACE_PARENT_HEADER] = testCases[testCase];
 
         const extractedSpanContext = getExtractedSpanContext(
-          httpTraceContext.extract(Context.ROOT_CONTEXT, carrier)
+          httpTraceContext.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
         );
         assert.deepStrictEqual(extractedSpanContext, undefined, testCase);
       });
diff --git a/packages/opentelemetry-core/test/context/composite.test.ts b/packages/opentelemetry-core/test/context/composite.test.ts
index 55b4b8ea8f..396f566558 100644
--- a/packages/opentelemetry-core/test/context/composite.test.ts
+++ b/packages/opentelemetry-core/test/context/composite.test.ts
@@ -14,6 +14,12 @@
  * limitations under the License.
  */
 
+import {
+  defaultGetter,
+  defaultSetter,
+  HttpTextFormat,
+  SpanContext,
+} from '@opentelemetry/api';
 import { Context } from '@opentelemetry/scope-base';
 import * as assert from 'assert';
 import {
@@ -23,21 +29,20 @@ import {
   randomTraceId,
 } from '../../src';
 import {
-  setExtractedSpanContext,
   getExtractedSpanContext,
+  setExtractedSpanContext,
 } from '../../src/context/context';
 import {
   B3Format,
+  X_B3_SAMPLED,
   X_B3_SPAN_ID,
   X_B3_TRACE_ID,
-  X_B3_SAMPLED,
 } from '../../src/context/propagation/B3Format';
 import {
   TRACE_PARENT_HEADER,
   TRACE_STATE_HEADER,
 } from '../../src/context/propagation/HttpTraceContext';
 import { TraceState } from '../../src/trace/TraceState';
-import { HttpTextFormat, SpanContext } from '@opentelemetry/api';
 
 describe('Composite Propagator', () => {
   let traceId: string;
@@ -71,7 +76,7 @@ describe('Composite Propagator', () => {
       const composite = new CompositePropagator({
         propagators: [new B3Format(), new HttpTraceContext()],
       });
-      composite.inject(ctxWithSpanContext, carrier);
+      composite.inject(ctxWithSpanContext, carrier, defaultSetter);
 
       assert.strictEqual(carrier[X_B3_TRACE_ID], traceId);
       assert.strictEqual(carrier[X_B3_SPAN_ID], spanId);
@@ -87,7 +92,7 @@ describe('Composite Propagator', () => {
       const composite = new CompositePropagator({
         propagators: [new ThrowingPropagator(), new HttpTraceContext()],
       });
-      composite.inject(ctxWithSpanContext, carrier);
+      composite.inject(ctxWithSpanContext, carrier, defaultSetter);
 
       assert.strictEqual(
         carrier[TRACE_PARENT_HEADER],
@@ -114,7 +119,7 @@ describe('Composite Propagator', () => {
         propagators: [new B3Format(), new HttpTraceContext()],
       });
       const spanContext = getExtractedSpanContext(
-        composite.extract(Context.ROOT_CONTEXT, carrier)
+        composite.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       if (!spanContext) {
@@ -133,7 +138,7 @@ describe('Composite Propagator', () => {
         propagators: [new ThrowingPropagator(), new HttpTraceContext()],
       });
       const spanContext = getExtractedSpanContext(
-        composite.extract(Context.ROOT_CONTEXT, carrier)
+        composite.extract(Context.ROOT_CONTEXT, carrier, defaultGetter)
       );
 
       if (!spanContext) {
diff --git a/packages/opentelemetry-plugin-grpc/src/grpc.ts b/packages/opentelemetry-plugin-grpc/src/grpc.ts
index 3e08a5a168..f53cd493ae 100644
--- a/packages/opentelemetry-plugin-grpc/src/grpc.ts
+++ b/packages/opentelemetry-plugin-grpc/src/grpc.ts
@@ -124,11 +124,9 @@ export class GrpcPlugin extends BasePlugin<grpc> {
   }
 
   private _setSpanContext(metadata: grpcTypes.Metadata): void {
-    const carrier = {};
-    propagation.inject(carrier);
-    for (const [k, v] of Object.entries(carrier)) {
-      metadata.set(k, v as string);
-    }
+    propagation.inject(metadata, (metadata, k, v) =>
+      metadata.set(k, v as grpcTypes.MetadataValue)
+    );
   }
 
   private _patchServer() {
@@ -170,40 +168,45 @@ export class GrpcPlugin extends BasePlugin<grpc> {
                 JSON.stringify(spanOptions)
               );
 
-              context.with(propagation.extract(call.metadata.getMap()), () => {
-                const span = plugin._tracer
-                  .startSpan(spanName, spanOptions)
-                  .setAttributes({
-                    [AttributeNames.GRPC_KIND]: spanOptions.kind,
-                    [AttributeNames.COMPONENT]: GrpcPlugin.component,
+              context.with(
+                propagation.extract(call.metadata, (carrier, key) =>
+                  carrier.get(key)
+                ),
+                () => {
+                  const span = plugin._tracer
+                    .startSpan(spanName, spanOptions)
+                    .setAttributes({
+                      [AttributeNames.GRPC_KIND]: spanOptions.kind,
+                      [AttributeNames.COMPONENT]: GrpcPlugin.component,
+                    });
+
+                  plugin._tracer.withSpan(span, () => {
+                    switch (type) {
+                      case 'unary':
+                      case 'client_stream':
+                        return plugin._clientStreamAndUnaryHandler(
+                          plugin,
+                          span,
+                          call,
+                          callback,
+                          originalFunc,
+                          self
+                        );
+                      case 'server_stream':
+                      case 'bidi':
+                        return plugin._serverStreamAndBidiHandler(
+                          plugin,
+                          span,
+                          call,
+                          originalFunc,
+                          self
+                        );
+                      default:
+                        break;
+                    }
                   });
-
-                plugin._tracer.withSpan(span, () => {
-                  switch (type) {
-                    case 'unary':
-                    case 'client_stream':
-                      return plugin._clientStreamAndUnaryHandler(
-                        plugin,
-                        span,
-                        call,
-                        callback,
-                        originalFunc,
-                        self
-                      );
-                    case 'server_stream':
-                    case 'bidi':
-                      return plugin._serverStreamAndBidiHandler(
-                        plugin,
-                        span,
-                        call,
-                        originalFunc,
-                        self
-                      );
-                    default:
-                      break;
-                  }
-                });
-              });
+                }
+              );
             };
           }
         );
diff --git a/packages/opentelemetry-propagator-jaeger/src/JaegerHttpTraceFormat.ts b/packages/opentelemetry-propagator-jaeger/src/JaegerHttpTraceFormat.ts
index be166154c0..45a85b7f0f 100644
--- a/packages/opentelemetry-propagator-jaeger/src/JaegerHttpTraceFormat.ts
+++ b/packages/opentelemetry-propagator-jaeger/src/JaegerHttpTraceFormat.ts
@@ -15,11 +15,12 @@
  */
 
 import {
-  Carrier,
   Context,
   HttpTextFormat,
   SpanContext,
   TraceFlags,
+  SetterFunction,
+  GetterFunction,
 } from '@opentelemetry/api';
 import {
   getParentSpanContext,
@@ -53,7 +54,7 @@ export class JaegerHttpTraceFormat implements HttpTextFormat {
     this._jaegerTraceHeader = customTraceHeader || UBER_TRACE_ID_HEADER;
   }
 
-  inject(context: Context, carrier: Carrier) {
+  inject(context: Context, carrier: unknown, setter: SetterFunction) {
     const spanContext = getParentSpanContext(context);
     if (!spanContext) return;
 
@@ -61,13 +62,15 @@ export class JaegerHttpTraceFormat implements HttpTextFormat {
       spanContext.traceFlags || TraceFlags.UNSAMPLED
     ).toString(16)}`;
 
-    carrier[
-      this._jaegerTraceHeader
-    ] = `${spanContext.traceId}:${spanContext.spanId}:0:${traceFlags}`;
+    setter(
+      carrier,
+      this._jaegerTraceHeader,
+      `${spanContext.traceId}:${spanContext.spanId}:0:${traceFlags}`
+    );
   }
 
-  extract(context: Context, carrier: Carrier): Context {
-    const uberTraceIdHeader = carrier[this._jaegerTraceHeader];
+  extract(context: Context, carrier: unknown, getter: GetterFunction): Context {
+    const uberTraceIdHeader = getter(carrier, this._jaegerTraceHeader);
     if (!uberTraceIdHeader) return context;
     const uberTraceId = Array.isArray(uberTraceIdHeader)
       ? uberTraceIdHeader[0]
diff --git a/packages/opentelemetry-propagator-jaeger/test/JaegerHttpTraceFormat.test.ts b/packages/opentelemetry-propagator-jaeger/test/JaegerHttpTraceFormat.test.ts
index c8e5e1b406..fb56229ad4 100644
--- a/packages/opentelemetry-propagator-jaeger/test/JaegerHttpTraceFormat.test.ts
+++ b/packages/opentelemetry-propagator-jaeger/test/JaegerHttpTraceFormat.test.ts
@@ -14,7 +14,13 @@
  * limitations under the License.
  */
 
-import { Context, SpanContext, TraceFlags } from '@opentelemetry/api';
+import {
+  Context,
+  defaultGetter,
+  defaultSetter,
+  SpanContext,
+  TraceFlags,
+} from '@opentelemetry/api';
 import {
   getExtractedSpanContext,
   setExtractedSpanContext,
@@ -45,7 +51,8 @@ describe('JaegerHttpTraceFormat', () => {
 
       jaegerHttpTraceFormat.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, spanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(
         carrier[UBER_TRACE_ID_HEADER],
@@ -62,7 +69,8 @@ describe('JaegerHttpTraceFormat', () => {
 
       customJaegerHttpTraceFormat.inject(
         setExtractedSpanContext(Context.ROOT_CONTEXT, spanContext),
-        carrier
+        carrier,
+        defaultSetter
       );
       assert.deepStrictEqual(
         carrier[customHeader],
@@ -76,7 +84,11 @@ describe('JaegerHttpTraceFormat', () => {
       carrier[UBER_TRACE_ID_HEADER] =
         'd4cda95b652f4a1592b449d5929fda1b:6e0c63257de34c92:0:01';
       const extractedSpanContext = getExtractedSpanContext(
-        jaegerHttpTraceFormat.extract(Context.ROOT_CONTEXT, carrier)
+        jaegerHttpTraceFormat.extract(
+          Context.ROOT_CONTEXT,
+          carrier,
+          defaultGetter
+        )
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -91,7 +103,11 @@ describe('JaegerHttpTraceFormat', () => {
       carrier[UBER_TRACE_ID_HEADER] =
         '9c41e35aeb6d1272:45fd2a9709dadcf1:a13699e3fb724f40:1';
       const extractedSpanContext = getExtractedSpanContext(
-        jaegerHttpTraceFormat.extract(Context.ROOT_CONTEXT, carrier)
+        jaegerHttpTraceFormat.extract(
+          Context.ROOT_CONTEXT,
+          carrier,
+          defaultGetter
+        )
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -106,7 +122,11 @@ describe('JaegerHttpTraceFormat', () => {
       carrier[UBER_TRACE_ID_HEADER] =
         'ac1f3dc3c2c0b06e%3A5ac292c4a11a163e%3Ac086aaa825821068%3A1';
       const extractedSpanContext = getExtractedSpanContext(
-        jaegerHttpTraceFormat.extract(Context.ROOT_CONTEXT, carrier)
+        jaegerHttpTraceFormat.extract(
+          Context.ROOT_CONTEXT,
+          carrier,
+          defaultGetter
+        )
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -121,7 +141,11 @@ describe('JaegerHttpTraceFormat', () => {
       carrier[customHeader] =
         'd4cda95b652f4a1592b449d5929fda1b:6e0c63257de34c92:0:01';
       const extractedSpanContext = getExtractedSpanContext(
-        customJaegerHttpTraceFormat.extract(Context.ROOT_CONTEXT, carrier)
+        customJaegerHttpTraceFormat.extract(
+          Context.ROOT_CONTEXT,
+          carrier,
+          defaultGetter
+        )
       );
 
       assert.deepStrictEqual(extractedSpanContext, {
@@ -135,7 +159,11 @@ describe('JaegerHttpTraceFormat', () => {
     it('returns undefined if UBER_TRACE_ID_HEADER header is missing', () => {
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          jaegerHttpTraceFormat.extract(Context.ROOT_CONTEXT, carrier)
+          jaegerHttpTraceFormat.extract(
+            Context.ROOT_CONTEXT,
+            carrier,
+            defaultGetter
+          )
         ),
         undefined
       );
@@ -145,7 +173,11 @@ describe('JaegerHttpTraceFormat', () => {
       carrier[UBER_TRACE_ID_HEADER] = 'invalid!';
       assert.deepStrictEqual(
         getExtractedSpanContext(
-          jaegerHttpTraceFormat.extract(Context.ROOT_CONTEXT, carrier)
+          jaegerHttpTraceFormat.extract(
+            Context.ROOT_CONTEXT,
+            carrier,
+            defaultGetter
+          )
         ),
         undefined
       );
diff --git a/packages/opentelemetry-shim-opentracing/src/shim.ts b/packages/opentelemetry-shim-opentracing/src/shim.ts
index a919393486..c854f4f5b0 100644
--- a/packages/opentelemetry-shim-opentracing/src/shim.ts
+++ b/packages/opentelemetry-shim-opentracing/src/shim.ts
@@ -22,6 +22,7 @@ import {
   setActiveSpan,
 } from '@opentelemetry/core';
 import * as opentracing from 'opentracing';
+import { defaultSetter } from '@opentelemetry/api';
 
 function translateReferences(references: opentracing.Reference[]): api.Link[] {
   const links: api.Link[] = [];
@@ -134,7 +135,7 @@ export class TracerShim extends opentracing.Tracer {
   _inject(
     spanContext: opentracing.SpanContext,
     format: string,
-    carrier: api.Carrier
+    carrier: unknown
   ): void {
     const opentelemSpanContext: api.SpanContext = (spanContext as SpanContextShim).getSpanContext();
     if (!carrier || typeof carrier !== 'object') return;
@@ -144,6 +145,7 @@ export class TracerShim extends opentracing.Tracer {
       case opentracing.FORMAT_TEXT_MAP:
         api.propagation.inject(
           carrier,
+          defaultSetter,
           setExtractedSpanContext(
             api.Context.ROOT_CONTEXT,
             opentelemSpanContext
@@ -160,10 +162,7 @@ export class TracerShim extends opentracing.Tracer {
     }
   }
 
-  _extract(
-    format: string,
-    carrier: api.Carrier
-  ): opentracing.SpanContext | null {
+  _extract(format: string, carrier: unknown): opentracing.SpanContext | null {
     switch (format) {
       // tslint:disable-next-line:no-switch-case-fall-through
       case opentracing.FORMAT_HTTP_HEADERS: