diff --git a/.gitignore b/.gitignore
index d05eb758..df66b908 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .dart_tool
 .packages
-pubspec.lock
\ No newline at end of file
+pubspec.lock
+lib/src/sdk/trace/exporters/opentelemetry
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 00000000..63943155
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "lib/src/sdk/trace/exporters/opentelemetry-proto"]
+	path = lib/src/sdk/trace/exporters/opentelemetry-proto
+	url = git@github.com:open-telemetry/opentelemetry-proto.git
diff --git a/Makefile b/Makefile
index 1a8dac7d..ba84775d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,20 @@
-deps:
-	@pub get
+init:
+	git submodule update --init
+	pub get
+	pub global activate protoc_plugin
+	cd lib/src/sdk/trace/exporters && \
+		protoc --proto_path opentelemetry-proto \
+		--dart_out . \
+		opentelemetry-proto/opentelemetry/proto/common/v1/common.proto \
+		opentelemetry-proto/opentelemetry/proto/collector/trace/v1/trace_service.proto \
+		opentelemetry-proto/opentelemetry/proto/trace/v1/trace.proto \
+		opentelemetry-proto/opentelemetry/proto/resource/v1/resource.proto
 
-analyze-lib:
+analyze:
 	@dart analyze ./lib
-
-analyze-test:
 	@dart analyze ./test
 
-test: analyze-lib
+test:
 	@dart test ./test --chain-stack-traces
 
-.PHONY: deps analyze-lib analyze-test test
+.PHONY: init analyze test
diff --git a/README.md b/README.md
index f9bbdcaf..62a749eb 100644
--- a/README.md
+++ b/README.md
@@ -63,4 +63,8 @@ main() async {
 
   span.end();
 }
-```
\ No newline at end of file
+```
+
+## Development
+
+In order to generate protobuf definitions, you must have [protoc](https://github.com/protocolbuffers/protobuf/releases) installed and available in your path.
diff --git a/analysis_options.yaml b/analysis_options.yaml
index c55a1abe..b721915f 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -1 +1,4 @@
 include: package:workiva_analysis_options/v1.recommended.yaml
+analyzer:
+  exclude: 
+    - src/sdk/trace/exporters/opentelemetry
diff --git a/lib/sdk.dart b/lib/sdk.dart
index abc4044b..2e0c90d5 100644
--- a/lib/sdk.dart
+++ b/lib/sdk.dart
@@ -1,3 +1,6 @@
+export 'src/sdk/trace/exporters/collector_exporter.dart'
+  show 
+    CollectorExporter;
 export 'src/sdk/trace/exporters/console_exporter.dart'
   show 
     ConsoleExporter;
diff --git a/lib/src/api/trace/id_generator.dart b/lib/src/api/trace/id_generator.dart
index 2adefd65..85f5b800 100644
--- a/lib/src/api/trace/id_generator.dart
+++ b/lib/src/api/trace/id_generator.dart
@@ -1,8 +1,8 @@
 /// Generator capable of creating OTel compliant IDs.
 abstract class IdGenerator {
   /// Generate an ID for a Span.
-  String generateSpanId();
+  List<int> generateSpanId();
 
   /// Generate an ID for a trace.
-  String generateTraceId();
+  List<int> generateTraceId();
 }
diff --git a/lib/src/api/trace/span.dart b/lib/src/api/trace/span.dart
index d526ae03..092200df 100644
--- a/lib/src/api/trace/span.dart
+++ b/lib/src/api/trace/span.dart
@@ -1,6 +1,7 @@
-import 'package:opentelemetry/src/api/trace/span_status.dart';
-
+import 'package:fixnum/fixnum.dart';
 import 'span_context.dart';
+import 'span_status.dart';
+import 'tracer.dart';
 
 /// A representation of a single operation within a trace.
 ///
@@ -17,13 +18,13 @@ abstract class Span {
   SpanContext get spanContext;
 
   /// Get the time when the span was closed, or null if still open.
-  int get endTime;
+  Int64 get endTime;
 
   /// Get the time when the span was started.
-  int get startTime;
+  Int64 get startTime;
 
   /// The parent span id.
-  String get parentSpanId;
+  List<int> get parentSpanId;
 
   /// The name of the span.
   String get name;
@@ -40,6 +41,9 @@ abstract class Span {
   /// Retrieve the status of the [Span].
   SpanStatus get status;
 
+  /// Tracer responsible for creating the [Span].
+  Tracer get tracer;
+
   /// Marks the end of this span's execution.
   void end();
 }
diff --git a/lib/src/api/trace/span_context.dart b/lib/src/api/trace/span_context.dart
index 91907977..c131f745 100644
--- a/lib/src/api/trace/span_context.dart
+++ b/lib/src/api/trace/span_context.dart
@@ -3,10 +3,10 @@ import 'trace_state.dart';
 /// Representation of the context of the context of an individual span.
 abstract class SpanContext {
   /// Get the ID of the span.
-  String get spanId;
+  List<int> get spanId;
 
   /// Get the ID of the trace the span is a part of.
-  String get traceId;
+  List<int> get traceId;
 
   /// Get the state of the entire trace.
   TraceState get traceState;
diff --git a/lib/src/api/trace/tracer.dart b/lib/src/api/trace/tracer.dart
index 27ace663..cae02fcd 100644
--- a/lib/src/api/trace/tracer.dart
+++ b/lib/src/api/trace/tracer.dart
@@ -9,4 +9,7 @@ abstract class Tracer {
   /// Starts a new [Span] without setting it as the current span in this
   /// tracer's context.
   Span startSpan(String name, {Context context});
+
+  /// The Tracer's name.
+  String get name;
 }
diff --git a/lib/src/sdk/trace/exporters/collector_exporter.dart b/lib/src/sdk/trace/exporters/collector_exporter.dart
new file mode 100644
index 00000000..add55bcb
--- /dev/null
+++ b/lib/src/sdk/trace/exporters/collector_exporter.dart
@@ -0,0 +1,82 @@
+import 'package:http/http.dart' as http;
+
+import '../../../api/trace/span.dart';
+import '../../../api/trace/span_status.dart';
+
+import 'opentelemetry/proto/collector/trace/v1/trace_service.pb.dart';
+import 'opentelemetry/proto/common/v1/common.pb.dart';
+import 'opentelemetry/proto/resource/v1/resource.pb.dart';
+import 'opentelemetry/proto/trace/v1/trace.pb.dart' as pb;
+import 'span_exporter.dart';
+
+class CollectorExporter implements SpanExporter {
+  Uri uri;
+  http.Client client;
+  var _isShutdown = false;
+
+  CollectorExporter(this.uri, {http.Client httpClient}) {
+    client = httpClient ?? http.Client();
+  }
+
+  @override
+  void export(List<Span> spans) {
+    if (_isShutdown) {
+      return;
+    }
+
+    if (spans.isEmpty) {
+      return;
+    }
+
+    final pbSpans = <pb.Span>[];
+    for (var i = 0; i < spans.length; i++) {
+      pbSpans.add(_spanToProtobuf(spans[i]));
+    }
+
+    final body = ExportTraceServiceRequest(resourceSpans: [
+      pb.ResourceSpans(
+          resource: Resource(attributes: [
+            KeyValue(
+                key: 'service.name',
+                value: AnyValue(stringValue: spans[0].tracer.name))
+          ]),
+          instrumentationLibrarySpans: [
+            pb.InstrumentationLibrarySpans(spans: pbSpans)
+          ])
+    ]);
+
+    client.post(uri,
+        body: body.writeToBuffer(),
+        headers: {'Content-Type': 'application/x-protobuf'});
+  }
+
+  pb.Span _spanToProtobuf(Span span) {
+    pb.Status_StatusCode statusCode;
+
+    switch (span.status.code) {
+      case StatusCode.UNSET:
+        statusCode = pb.Status_StatusCode.STATUS_CODE_UNSET;
+        break;
+      case StatusCode.ERROR:
+        statusCode = pb.Status_StatusCode.STATUS_CODE_ERROR;
+        break;
+      case StatusCode.OK:
+        statusCode = pb.Status_StatusCode.STATUS_CODE_OK;
+        break;
+    }
+
+    return pb.Span(
+        traceId: span.spanContext.traceId,
+        spanId: span.spanContext.spanId,
+        parentSpanId: span.parentSpanId,
+        name: span.name,
+        startTimeUnixNano: span.startTime * 1000,
+        endTimeUnixNano: span.endTime * 1000,
+        status: pb.Status(code: statusCode, message: span.status.description));
+  }
+
+  @override
+  void shutdown() {
+    _isShutdown = true;
+  }
+}
diff --git a/lib/src/sdk/trace/exporters/console_exporter.dart b/lib/src/sdk/trace/exporters/console_exporter.dart
index 5ba63f13..fe98809a 100644
--- a/lib/src/sdk/trace/exporters/console_exporter.dart
+++ b/lib/src/sdk/trace/exporters/console_exporter.dart
@@ -9,10 +9,16 @@ class ConsoleExporter implements SpanExporter {
     for (var i=0; i < spans.length; i++) {
       final span = spans[i];
       print({
-        'traceId': span.spanContext.traceId,
-        'parentId': span.parentSpanId,
+        'traceId': span.spanContext.traceId
+            .map((x) => x.toRadixString(16).padLeft(2, '0'))
+            .join(),
+        'parentId': span.parentSpanId
+            .map((x) => x.toRadixString(16).padLeft(2, '0'))
+            .join(),
         'name': span.name,
-        'id': span.spanContext.spanId,
+        'id': span.spanContext.spanId
+            .map((x) => x.toRadixString(16).padLeft(2, '0'))
+            .join(),
         'timestamp': span.startTime,
         'duration': span.endTime - span.startTime,
         'status': span.status.code
diff --git a/lib/src/sdk/trace/exporters/opentelemetry-proto b/lib/src/sdk/trace/exporters/opentelemetry-proto
new file mode 160000
index 00000000..86724942
--- /dev/null
+++ b/lib/src/sdk/trace/exporters/opentelemetry-proto
@@ -0,0 +1 @@
+Subproject commit 8672494217bfc858e2a82a4e8c623d4a5530473a
diff --git a/lib/src/sdk/trace/id_generator.dart b/lib/src/sdk/trace/id_generator.dart
index 2b1f272e..1dfbca29 100644
--- a/lib/src/sdk/trace/id_generator.dart
+++ b/lib/src/sdk/trace/id_generator.dart
@@ -6,17 +6,17 @@ import '../../../src/api/trace/id_generator.dart' as api;
 class IdGenerator implements api.IdGenerator {
   static final Random _random = Random.secure();
 
-  static String _generateId(int byteLength) {
-    final buffer = StringBuffer();
+  static List<int> _generateId(int byteLength) {
+    final buffer = [];
     for (var i = 0; i < byteLength; i++) {
-      buffer.write(_random.nextInt(256).toRadixString(16).padLeft(2, '0'));
+      buffer.add(_random.nextInt(256));
     }
-    return buffer.toString();
+    return buffer.cast<int>();
   }
   
   @override
-  String generateSpanId() => _generateId(8);
+  List<int> generateSpanId() => _generateId(8);
 
   @override
-  String generateTraceId() => _generateId(16);
+  List<int> generateTraceId() => _generateId(16);
 }
diff --git a/lib/src/sdk/trace/span.dart b/lib/src/sdk/trace/span.dart
index 28963723..9ed83fb0 100644
--- a/lib/src/sdk/trace/span.dart
+++ b/lib/src/sdk/trace/span.dart
@@ -1,28 +1,28 @@
+import 'package:fixnum/fixnum.dart';
+
 import '../../api/trace/span.dart' as span_api;
 import '../../api/trace/span_context.dart';
 import '../../api/trace/span_status.dart';
+import '../../api/trace/tracer.dart';
 import 'span_processors/span_processor.dart';
 
 /// A representation of a single operation within a trace.
 class Span implements span_api.Span {
-  int _startTime;
-  int _endTime;
-  final String _parentSpanId;
+  Int64 _startTime;
+  Int64 _endTime;
+  final List<int> _parentSpanId;
   final SpanContext _spanContext;
   final SpanStatus _status = SpanStatus();
   final List<SpanProcessor> _processors;
+  final Tracer _tracer;
 
   @override
   String name;
 
   /// Construct a [Span].
-  Span(
-    this.name, 
-    this._spanContext, 
-    this._parentSpanId,
-    this._processors
-  ) {
-    _startTime = DateTime.now().toUtc().microsecondsSinceEpoch;
+  Span(this.name, this._spanContext, this._parentSpanId, this._processors,
+      this._tracer) {
+    _startTime = Int64(DateTime.now().toUtc().microsecondsSinceEpoch);
     for (var i = 0; i < _processors.length; i++) {
       _processors[i].onStart();
     }
@@ -32,17 +32,17 @@ class Span implements span_api.Span {
   SpanContext get spanContext => _spanContext;
 
   @override
-  int get endTime => _endTime;
+  Int64 get endTime => _endTime;
 
   @override
-  int get startTime => _startTime;
+  Int64 get startTime => _startTime;
 
   @override
-  String get parentSpanId => _parentSpanId;
+  List<int> get parentSpanId => _parentSpanId;
 
   @override
   void end() {
-    _endTime ??= DateTime.now().toUtc().microsecondsSinceEpoch;
+    _endTime ??= Int64(DateTime.now().toUtc().microsecondsSinceEpoch);
     for (var i = 0; i < _processors.length; i++) {
       _processors[i].onEnd(this);
     }
@@ -66,4 +66,7 @@ class Span implements span_api.Span {
 
   @override
   SpanStatus get status => _status;
+
+  @override
+  Tracer get tracer => _tracer;
 }
diff --git a/lib/src/sdk/trace/span_context.dart b/lib/src/sdk/trace/span_context.dart
index 9f35e5c2..c24ea27a 100644
--- a/lib/src/sdk/trace/span_context.dart
+++ b/lib/src/sdk/trace/span_context.dart
@@ -3,15 +3,15 @@ import '../../../src/api/trace/trace_state.dart';
 
 /// Representation of the context of the context of an individual span.
 class SpanContext implements span_context_api.SpanContext {
-  final String _spanId;
-  final String _traceId;
+  final List<int> _spanId;
+  final List<int> _traceId;
   final TraceState _traceState;
 
   @override
-  String get spanId => _spanId;
+  List<int> get spanId => _spanId;
 
   @override
-  String get traceId => _traceId;
+  List<int> get traceId => _traceId;
 
   @override
   TraceState get traceState => _traceState;
diff --git a/lib/src/sdk/trace/span_processors/batch_processor.dart b/lib/src/sdk/trace/span_processors/batch_processor.dart
index 31ad998c..4e91ca76 100644
--- a/lib/src/sdk/trace/span_processors/batch_processor.dart
+++ b/lib/src/sdk/trace/span_processors/batch_processor.dart
@@ -15,13 +15,13 @@ class BatchSpanProcessor implements SpanProcessor {
   final List<Span> _spanBuffer = [];
   Timer _timer; 
 
-  int _maxExportBatchSize = 512;
+  int _maxExportBatchSize;
   final int _maxQueueSize = 2048;
-  int _scheduledDelay = 5000;
+  int _scheduledDelay;
 
   BatchSpanProcessor(this._exporter, {int maxExportBatchSize, int scheduledDelay}) {
-    _maxExportBatchSize = maxExportBatchSize;
-    _scheduledDelay = scheduledDelay;
+    _maxExportBatchSize = maxExportBatchSize ?? 512;
+    _scheduledDelay = scheduledDelay ?? 5000;
   }
 
   @override
diff --git a/lib/src/sdk/trace/tracer.dart b/lib/src/sdk/trace/tracer.dart
index 14bd18da..c9e8fb54 100644
--- a/lib/src/sdk/trace/tracer.dart
+++ b/lib/src/sdk/trace/tracer.dart
@@ -9,17 +9,21 @@ import 'span_processors/span_processor.dart';
 
 /// An interface for creating [Span]s and propagating context in-process.
 class Tracer implements tracer_api.Tracer {
+  final String _name;
   final IdGenerator _idGenerator = IdGenerator();
   final List<SpanProcessor> _processors;
 
-  Tracer(this._processors);
+  Tracer(this._name, this._processors);
+
+  @override
+  String get name => _name;
 
   @override
   Span startSpan(String name, {Context context}) {
     context ??= Context.current;
 
-    String parentSpanId;
-    String traceId;
+    List<int> parentSpanId;
+    List<int> traceId;
     TraceState traceState;
     
     final spanId = _idGenerator.generateSpanId();
@@ -36,6 +40,6 @@ class Tracer implements tracer_api.Tracer {
 
     final spanContext = SpanContext(traceId, spanId, traceState);
 
-    return Span(name, spanContext, parentSpanId, _processors);
+    return Span(name, spanContext, parentSpanId, _processors, this);
   }
 }
diff --git a/lib/src/sdk/trace/tracer_provider.dart b/lib/src/sdk/trace/tracer_provider.dart
index 86d771f7..1edab1ac 100644
--- a/lib/src/sdk/trace/tracer_provider.dart
+++ b/lib/src/sdk/trace/tracer_provider.dart
@@ -22,7 +22,7 @@ class TracerProvider implements api.TracerProvider {
   @override
   Tracer getTracer(String name, {String version = ''}) {
     final key = '$name@$version';
-    return _tracers.putIfAbsent(key, () => Tracer(_processors));
+    return _tracers.putIfAbsent(key, () => Tracer(name, _processors));
   }
 
   @override
diff --git a/pubspec.yaml b/pubspec.yaml
index fe4a5341..8b14fc2c 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,7 +4,9 @@ environment:
   sdk: '>=2.7.0 <3.0.0'
 
 dependencies:
+  http: ^0.12.2
   logging: ^0.11.4
+  protobuf: ^2.0.0
 
 dev_dependencies:
   mockito: ^5.0.13
diff --git a/test/integration/sdk/span_test.dart b/test/integration/sdk/span_test.dart
index 3b83f785..0f735d07 100644
--- a/test/integration/sdk/span_test.dart
+++ b/test/integration/sdk/span_test.dart
@@ -3,6 +3,7 @@ import 'package:mockito/mockito.dart';
 import 'package:opentelemetry/src/sdk/trace/span.dart';
 import 'package:opentelemetry/src/sdk/trace/span_context.dart';
 import 'package:opentelemetry/src/sdk/trace/trace_state.dart';
+import 'package:opentelemetry/src/sdk/trace/tracer.dart';
 import 'package:test/test.dart';
 
 import '../../unit/mocks.dart';
@@ -11,14 +12,12 @@ void main() {
   test('span set and end time', () {
     final mockProcessor1 = MockSpanProcessor();
     final mockProcessor2 = MockSpanProcessor();
-    final span = Span('foo', SpanContext('trace123', '789', TraceState()), 'span456', [
-      mockProcessor1,
-      mockProcessor2
-    ]);
+    final span = Span('foo', SpanContext([1, 2, 3], [7, 8, 9], TraceState()),
+        [4, 5, 6], [mockProcessor1, mockProcessor2], Tracer('bar', []));
 
-    expect(span.startTime, isA<int>());
+    expect(span.startTime, isNotNull);
     expect(span.endTime, isNull);
-    expect(span.parentSpanId, 'span456');
+    expect(span.parentSpanId, [4, 5, 6]);
     expect(span.name, 'foo');
 
     verify(mockProcessor1.onStart()).called(1);
@@ -27,8 +26,8 @@ void main() {
     verifyNever(mockProcessor2.onEnd(span));
 
     span.end();
-    expect(span.startTime, isA<int>());
-    expect(span.endTime, isA<int>());
+    expect(span.startTime, isNotNull);
+    expect(span.endTime, isNotNull);
     expect(span.endTime, greaterThan(span.startTime));
 
     verify(mockProcessor1.onEnd(span)).called(1);
@@ -36,8 +35,8 @@ void main() {
   });
 
   test('span status', () {
-    final span =
-        Span('foo', SpanContext('trace123', '789', TraceState()), 'span456', []);
+    final span = Span('foo', SpanContext([1, 2, 3], [7, 8, 9], TraceState()),
+        [4, 5, 6], [], Tracer('bar', []));
 
     // Verify span status' defaults.
     expect(span.status.code, equals(StatusCode.UNSET));
diff --git a/test/integration/sdk/tracer_test.dart b/test/integration/sdk/tracer_test.dart
index 9973d464..e963f33e 100644
--- a/test/integration/sdk/tracer_test.dart
+++ b/test/integration/sdk/tracer_test.dart
@@ -5,30 +5,30 @@ import 'package:test/test.dart';
 
 void main() {
   test('startSpan new trace', () {
-    final tracer = Tracer([]);
+    final tracer = Tracer('bar', []);
 
     final span = tracer.startSpan('foo');
 
-    expect(span.startTime, isA<int>());
+    expect(span.startTime, isNotNull);
     expect(span.endTime, isNull);
-    expect(span.spanContext.traceId, isA<String>());
-    expect(span.spanContext.spanId, isA<String>());
+    expect(span.spanContext.traceId, isNotNull);
+    expect(span.spanContext.spanId, isNotNull);
   });
 
   test('startSpan child span', () {
-    final tracer = Tracer([]);
+    final tracer = Tracer('baz', []);
 
     final parentSpan = tracer.startSpan('foo');
     final context = setSpan(Context.current, parentSpan);
 
     final childSpan = tracer.startSpan('bar', context: context);
 
-    expect(childSpan.startTime, isA<int>());
+    expect(childSpan.startTime, isNotNull);
     expect(childSpan.endTime, isNull);
     expect(childSpan.spanContext.traceId, equals(parentSpan.spanContext.traceId));
     expect(childSpan.spanContext.traceState, equals(parentSpan.spanContext.traceState));
     expect(childSpan.spanContext.spanId, allOf([
-      isA<String>(),
+      isNotNull,
       isNot(equals(parentSpan.spanContext.spanId))
     ]));
   });
diff --git a/test/unit/api/context_utils_test.dart b/test/unit/api/context_utils_test.dart
index 555c3c49..92428a63 100644
--- a/test/unit/api/context_utils_test.dart
+++ b/test/unit/api/context_utils_test.dart
@@ -4,13 +4,15 @@ import 'package:opentelemetry/src/api/trace/context_utils.dart';
 import 'package:opentelemetry/src/sdk/trace/span.dart';
 import 'package:opentelemetry/src/sdk/trace/span_context.dart';
 import 'package:opentelemetry/src/sdk/trace/trace_state.dart';
+import 'package:opentelemetry/src/sdk/trace/tracer.dart';
 import 'package:test/test.dart';
 
 import '../mocks.dart';
 
 void main() {
-  final testSpanContext = SpanContext('123', '789', TraceState());
-  final testSpan = Span('foo', testSpanContext, '456', []);
+  final testSpanContext = SpanContext([1, 2, 3], [7, 8, 9], TraceState());
+  final testSpan =
+      Span('foo', testSpanContext, [4, 5, 6], [], Tracer('bar', []));
 
   group('getSpan', () {
     test('returns Span when exists', () {
diff --git a/test/unit/mocks.dart b/test/unit/mocks.dart
index 11f4b2ae..1b94a2a5 100644
--- a/test/unit/mocks.dart
+++ b/test/unit/mocks.dart
@@ -1,3 +1,4 @@
+import 'package:http/http.dart' as http;
 import 'package:mockito/mockito.dart';
 import 'package:opentelemetry/src/api/context/context.dart';
 import 'package:opentelemetry/src/api/trace/span.dart';
@@ -5,6 +6,7 @@ import 'package:opentelemetry/src/sdk/trace/exporters/span_exporter.dart';
 import 'package:opentelemetry/src/sdk/trace/span_processors/span_processor.dart';
 
 class MockContext extends Mock implements Context {}
+class MockHTTPClient extends Mock implements http.Client {}
 class MockSpan extends Mock implements Span {}
 class MockSpanExporter extends Mock implements SpanExporter {}
 class MockSpanProcessor extends Mock implements SpanProcessor {}
diff --git a/test/unit/sdk/exporters/collector_exporter_test.dart b/test/unit/sdk/exporters/collector_exporter_test.dart
new file mode 100644
index 00000000..f70d9614
--- /dev/null
+++ b/test/unit/sdk/exporters/collector_exporter_test.dart
@@ -0,0 +1,94 @@
+import 'package:mockito/mockito.dart';
+import 'package:opentelemetry/src/sdk/trace/exporters/collector_exporter.dart';
+import 'package:opentelemetry/src/sdk/trace/exporters/opentelemetry/proto/collector/trace/v1/trace_service.pb.dart';
+import 'package:opentelemetry/src/sdk/trace/exporters/opentelemetry/proto/common/v1/common.pb.dart';
+import 'package:opentelemetry/src/sdk/trace/exporters/opentelemetry/proto/resource/v1/resource.pb.dart';
+import 'package:opentelemetry/src/sdk/trace/exporters/opentelemetry/proto/trace/v1/trace.pb.dart'
+    as pb;
+import 'package:opentelemetry/src/sdk/trace/span.dart';
+import 'package:opentelemetry/src/sdk/trace/span_context.dart';
+import 'package:opentelemetry/src/sdk/trace/trace_state.dart';
+import 'package:opentelemetry/src/sdk/trace/tracer.dart';
+import 'package:test/test.dart';
+
+import '../../mocks.dart';
+
+void main() {
+  MockHTTPClient mockClient;
+  final uri =
+      Uri.parse('https://h.wdesk.org/s/opentelemetry-collector/v1/traces');
+
+  setUp(() {
+    mockClient = MockHTTPClient();
+  });
+
+  tearDown(() {
+    reset(mockClient);
+  });
+
+  test('sends spans', () {
+    final tracer = Tracer('bar', []);
+    final span1 = Span('foo', SpanContext([1, 2, 3], [7, 8, 9], TraceState()),
+        [4, 5, 6], [], tracer)
+      ..end();
+    final span2 = Span(
+        'baz',
+        SpanContext([1, 2, 3], [10, 11, 12], TraceState()),
+        [4, 5, 6],
+        [],
+        tracer)
+      ..end();
+
+    CollectorExporter(uri, httpClient: mockClient).export([span1, span2]);
+
+    final expectedBody = ExportTraceServiceRequest(resourceSpans: [
+      pb.ResourceSpans(
+          resource: Resource(attributes: [
+            KeyValue(key: 'service.name', value: AnyValue(stringValue: 'bar'))
+          ]),
+          instrumentationLibrarySpans: [
+            pb.InstrumentationLibrarySpans(spans: [
+              pb.Span(
+                  traceId: [1, 2, 3],
+                  spanId: [7, 8, 9],
+                  parentSpanId: [4, 5, 6],
+                  name: 'foo',
+                  startTimeUnixNano: span1.startTime * 1000,
+                  endTimeUnixNano: span1.endTime * 1000,
+                  status: pb.Status(
+                      code: pb.Status_StatusCode.STATUS_CODE_UNSET,
+                      message: null)),
+              pb.Span(
+                  traceId: [1, 2, 3],
+                  spanId: [10, 11, 12],
+                  parentSpanId: [4, 5, 6],
+                  name: 'baz',
+                  startTimeUnixNano: span2.startTime * 1000,
+                  endTimeUnixNano: span2.endTime * 1000,
+                  status: pb.Status(
+                      code: pb.Status_StatusCode.STATUS_CODE_UNSET,
+                      message: null))
+            ])
+          ])
+    ]);
+
+    verify(mockClient.post(uri,
+        body: expectedBody.writeToBuffer(),
+        headers: {'Content-Type': 'application/x-protobuf'})).called(1);
+  });
+
+  test('does not send spans when shutdown', () {
+    final tracer = Tracer('bar', []);
+    final span = Span('foo', SpanContext([1, 2, 3], [7, 8, 9], TraceState()),
+        [4, 5, 6], [], tracer)
+      ..end();
+
+    CollectorExporter(uri, httpClient: mockClient)
+      ..shutdown()
+      ..export([span]);
+
+    verifyNever(mockClient.post(uri,
+        body: anything,
+        headers: {'Content-Type': 'application/x-protobuf'}));
+  });
+}
diff --git a/test/unit/sdk/exporters/console_exporter_test.dart b/test/unit/sdk/exporters/console_exporter_test.dart
index 2ce46614..988f3b09 100644
--- a/test/unit/sdk/exporters/console_exporter_test.dart
+++ b/test/unit/sdk/exporters/console_exporter_test.dart
@@ -4,6 +4,7 @@ import 'package:opentelemetry/src/sdk/trace/exporters/console_exporter.dart';
 import 'package:opentelemetry/src/sdk/trace/span.dart';
 import 'package:opentelemetry/src/sdk/trace/span_context.dart';
 import 'package:opentelemetry/src/sdk/trace/trace_state.dart';
+import 'package:opentelemetry/src/sdk/trace/tracer.dart';
 import 'package:test/test.dart';
 
 List<String> printLogs = [];
@@ -24,18 +25,21 @@ void main() {
   });
 
   test('prints', overridePrint(() {
-    final span = Span('foo', SpanContext('trace123', 'span789', TraceState()), 'span456', [])
-    ..end();
+    final span = Span('foo', SpanContext([1, 2, 3], [7, 8, 9], TraceState()),
+        [4, 5, 6], [], Tracer('bar', []))
+      ..end();
 
     ConsoleExporter().export([span]);
 
-    final expected = RegExp(r'^{traceId: trace123, parentId: span456, name: foo, id: span789, timestamp: \d+, duration: \d+, status: StatusCode.UNSET}$');
+    final expected = RegExp(
+        r'{traceId: 010203, parentId: 040506, name: foo, id: 070809, timestamp: \d+, duration: \d+, status: StatusCode.UNSET}');
     expect(printLogs.length, 1);
     expect(expected.hasMatch(printLogs[0]), true);
   }));
 
   test('does not print after shutdown', overridePrint(() {
-    final span = Span('foo', SpanContext('trace123', 'span789', TraceState()), 'span456', []);
+    final span = Span('foo', SpanContext([1, 2, 3], [7, 8, 9], TraceState()),
+        [4, 5, 6], [], Tracer('bar', []));
 
     ConsoleExporter()
     ..shutdown()
diff --git a/test/unit/sdk/id_generator_test.dart b/test/unit/sdk/id_generator_test.dart
index 5349f8ed..0c658341 100644
--- a/test/unit/sdk/id_generator_test.dart
+++ b/test/unit/sdk/id_generator_test.dart
@@ -5,10 +5,10 @@ void main() {
   final generator = IdGenerator();
   
   test('generateSpanId is the correct length', () {
-    expect(generator.generateSpanId().length, equals(16));
+    expect(generator.generateSpanId().length, equals(8));
   });
 
   test('generateTraceId is the correct length', () {
-    expect(generator.generateTraceId().length, equals(32));
+    expect(generator.generateTraceId().length, equals(16));
   });
 }
diff --git a/test/unit/sdk/span_context_test.dart b/test/unit/sdk/span_context_test.dart
index 1ba36583..1966f3ab 100644
--- a/test/unit/sdk/span_context_test.dart
+++ b/test/unit/sdk/span_context_test.dart
@@ -5,10 +5,10 @@ import 'package:test/test.dart';
 void main() {
   test('spanContext getters', () {
     final traceState = TraceState();
-    final spanContext = SpanContext('trace123', 'span456', traceState);
+    final spanContext = SpanContext([1, 2, 3], [4, 5, 6], traceState);
 
-    expect(spanContext.traceId, equals('trace123'));
-    expect(spanContext.spanId, equals('span456'));
+    expect(spanContext.traceId, [1, 2, 3]);
+    expect(spanContext.spanId, [4, 5, 6]);
     expect(spanContext.traceState, same(traceState));
   });
 }
diff --git a/test/unit/sdk/span_test.dart b/test/unit/sdk/span_test.dart
index b2dd62c8..17d46930 100644
--- a/test/unit/sdk/span_test.dart
+++ b/test/unit/sdk/span_test.dart
@@ -1,11 +1,13 @@
 import 'package:opentelemetry/src/sdk/trace/span.dart';
 import 'package:opentelemetry/src/sdk/trace/span_context.dart';
 import 'package:opentelemetry/src/sdk/trace/trace_state.dart';
+import 'package:opentelemetry/src/sdk/trace/tracer.dart';
 import 'package:test/test.dart';
 
 void main() {
   test('span change name', () {
-    final span = Span('foo', SpanContext('trace123', '789', TraceState()), 'span456', []);
+    final span = Span('foo', SpanContext([1, 2, 3], [7, 8, 9], TraceState()),
+        [4, 5, 6], [], Tracer('bar', []));
     expect(span.name, 'foo');
 
     span.name = 'bar';