diff --git a/README.md b/README.md
index 8b13789..7b12932 100644
--- a/README.md
+++ b/README.md
@@ -1 +1 @@
-
+# Language Independent Interface Types For OpenTelemetry
diff --git a/src/opentelemetry/proto/agent/README.md b/src/opentelemetry/proto/agent/README.md
new file mode 100644
index 0000000..c54b9bc
--- /dev/null
+++ b/src/opentelemetry/proto/agent/README.md
@@ -0,0 +1,10 @@
+# OpenTelemetry Agent Proto
+
+This package describes the OpenTelemetry Agent protocol.
+
+## Packages
+
+1. `common` package contains the common messages shared between different services, such as
+`Node`, `Service` and `Library` identifiers.
+2. `trace` package contains the Trace Service protos.
+3. `metrics` package contains the Metrics Service protos.
\ No newline at end of file
diff --git a/src/opentelemetry/proto/agent/common/v1/common.proto b/src/opentelemetry/proto/agent/common/v1/common.proto
new file mode 100644
index 0000000..45cd8a4
--- /dev/null
+++ b/src/opentelemetry/proto/agent/common/v1/common.proto
@@ -0,0 +1,96 @@
+// Copyright 2019, 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.
+
+syntax = "proto3";
+
+// NOTE: This proto is experimental and is subject to change at this point.
+// Please do not use it at the moment.
+
+package opentelemetry.proto.agent.common.v1;
+
+import "google/protobuf/timestamp.proto";
+
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.agent.common.v1";
+option java_outer_classname = "CommonProto";
+
+// Identifier metadata of the Node that produces the span or tracing data.
+// Note, this is not the metadata about the Node or service that is described by associated spans.
+// In the future we plan to extend the identifier proto definition to support
+// additional information (e.g cloud id, etc.)
+message Node {
+  // Identifier that uniquely identifies a process within a VM/container.
+  ProcessIdentifier identifier = 1;
+
+  // Information on the OpenTelemetry Library that initiates the stream.
+  LibraryInfo library_info = 2;
+
+  // Additional information on service.
+  ServiceInfo service_info = 3;
+
+  // Additional attributes.
+  map<string, string> attributes = 4;
+
+  // TODO(songya): Add more identifiers in the future as needed, like cloud
+  // identifiers.
+}
+
+// Identifier that uniquely identifies a process within a VM/container.
+message ProcessIdentifier {
+
+  // The host name. Usually refers to the machine/container name.
+  // For example: os.Hostname() in Go, socket.gethostname() in Python.
+  string host_name = 1;
+
+  // Process id.
+  uint32 pid = 2;
+
+  // Start time of this ProcessIdentifier. Represented in epoch time.
+  google.protobuf.Timestamp start_timestamp = 3;
+}
+
+// Information on OpenTelemetry Library.
+message LibraryInfo {
+
+  enum Language {
+    LANGUAGE_UNSPECIFIED = 0;
+    CPP = 1;
+    C_SHARP = 2;
+    ERLANG = 3;
+    GO_LANG = 4;
+    JAVA = 5;
+    NODE_JS = 6;
+    PHP = 7;
+    PYTHON = 8;
+    RUBY = 9;
+  }
+
+  // Language of OpenTelemetry Library.
+  Language language = 1;
+
+  // Version of Agent exporter of Library.
+  string exporter_version = 2;
+
+  // Version of OpenTelemetry Library.
+  string core_library_version = 3;
+}
+
+// Additional service information.
+message ServiceInfo {
+
+  // Name of the service.
+  string name = 1;
+
+  // TODO(songya): add more fields as needed.
+}
diff --git a/src/opentelemetry/proto/agent/metrics/v1/metrics_service.proto b/src/opentelemetry/proto/agent/metrics/v1/metrics_service.proto
new file mode 100644
index 0000000..f6c3f36
--- /dev/null
+++ b/src/opentelemetry/proto/agent/metrics/v1/metrics_service.proto
@@ -0,0 +1,54 @@
+// Copyright 2019, 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.
+
+syntax = "proto3";
+
+package opentelemetry.proto.agent.metrics.v1;
+
+import "agent/common/v1/common.proto";
+import "metrics/v1/metrics.proto";
+import "resource/v1/resource.proto";
+
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.agent.metrics.v1";
+option java_outer_classname = "MetricsServiceProto";
+
+// Service that can be used to push metrics between one Application
+// instrumented with OpenTelemetry and an agent, or between an agent and a
+// central collector.
+service MetricsService {
+  // For performance reasons, it is recommended to keep this RPC
+  // alive for the entire life of the application.
+  rpc Export(stream ExportMetricsServiceRequest) returns (stream ExportMetricsServiceResponse) {}
+}
+
+message ExportMetricsServiceRequest {
+  // This is required only in the first message on the stream or if the
+  // previous sent ExportMetricsServiceRequest message has a different Node (e.g.
+  // when the same RPC is used to send Metrics from multiple Applications).
+  opentelemetry.proto.agent.common.v1.Node node = 1;
+
+  // A list of metrics that belong to the last received Node.
+  repeated opentelemetry.proto.metrics.v1.Metric metrics = 2;
+
+  // The resource for the metrics in this message that do not have an explicit
+  // resource set.
+  // If unset, the most recently set resource in the RPC stream applies. It is
+  // valid to never be set within a stream, e.g. when no resource info is known
+  // at all or when all sent metrics have an explicit resource set.
+  opentelemetry.proto.resource.v1.Resource resource = 3;
+}
+
+message ExportMetricsServiceResponse {
+}
diff --git a/src/opentelemetry/proto/agent/trace/v1/trace_service.proto b/src/opentelemetry/proto/agent/trace/v1/trace_service.proto
new file mode 100644
index 0000000..75d77a0
--- /dev/null
+++ b/src/opentelemetry/proto/agent/trace/v1/trace_service.proto
@@ -0,0 +1,83 @@
+// Copyright 2019, 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.
+
+syntax = "proto3";
+
+// NOTE: This proto is experimental and is subject to change at this point.
+// Please do not use it at the moment.
+
+package opentelemetry.proto.agent.trace.v1;
+
+import "agent/common/v1/common.proto";
+import "resource/v1/resource.proto";
+import "trace/v1/trace.proto";
+import "trace/v1/trace_config.proto";
+
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.agent.trace.v1";
+option java_outer_classname = "TraceServiceProto";
+
+// Service that can be used to push spans and configs between one Application
+// instrumented with OpenTelemetry and an agent, or between an agent and a
+// central collector or config service (in this case spans and configs are
+// sent/received to/from multiple Applications).
+service TraceService {
+  // After initialization, this RPC must be kept alive for the entire life of
+  // the application. The agent pushes configs down to applications via a
+  // stream.
+  rpc Config(stream CurrentLibraryConfig) returns (stream UpdatedLibraryConfig) {}
+
+  // For performance reasons, it is recommended to keep this RPC
+  // alive for the entire life of the application.
+  rpc Export(stream ExportTraceServiceRequest) returns (stream ExportTraceServiceResponse) {}
+}
+
+message CurrentLibraryConfig {
+  // This is required only in the first message on the stream or if the
+  // previous sent CurrentLibraryConfig message has a different Node (e.g.
+  // when the same RPC is used to configure multiple Applications).
+  opentelemetry.proto.agent.common.v1.Node node = 1;
+
+  // Current configuration.
+  opentelemetry.proto.trace.v1.TraceConfig config = 2;
+}
+
+message UpdatedLibraryConfig {
+  // This field is ignored when the RPC is used to configure only one Application.
+  // This is required only in the first message on the stream or if the
+  // previous sent UpdatedLibraryConfig message has a different Node.
+  opentelemetry.proto.agent.common.v1.Node node = 1;
+
+  // Requested updated configuration.
+  opentelemetry.proto.trace.v1.TraceConfig config = 2;
+}
+
+message ExportTraceServiceRequest {
+  // This is required only in the first message on the stream or if the
+  // previous sent ExportTraceServiceRequest message has a different Node (e.g.
+  // when the same RPC is used to send Spans from multiple Applications).
+  opentelemetry.proto.agent.common.v1.Node node = 1;
+
+  // A list of Spans that belong to the last received Node.
+  repeated opentelemetry.proto.trace.v1.Span spans = 2;
+
+  // The resource for the spans in this message that do not have an explicit
+  // resource set.
+  // If unset, the most recently set resource in the RPC stream applies. It is
+  // valid to never be set within a stream, e.g. when no resource info is known.
+  opentelemetry.proto.resource.v1.Resource resource = 3;
+}
+
+message ExportTraceServiceResponse {
+}
diff --git a/src/opentelemetry/proto/agent/trace/v1/trace_service_http.yaml b/src/opentelemetry/proto/agent/trace/v1/trace_service_http.yaml
new file mode 100644
index 0000000..8a8b86d
--- /dev/null
+++ b/src/opentelemetry/proto/agent/trace/v1/trace_service_http.yaml
@@ -0,0 +1,12 @@
+# This is an API configuration to generate an HTTP/JSON -> gRPC gateway for the
+# OpenTelemetry service using github.com/grpc-ecosystem/grpc-gateway.
+type: google.api.Service
+config_version: 3
+http:
+ rules:
+ - selector: opentelemetry.proto.agent.trace.v1.TraceService.Export
+   post: /v1/trace
+   body: "*"
+ - selector: opentelemetry.proto.agent.metrics.v1.MetricsService.Export
+   post: /v1/trace
+   body: "*"
\ No newline at end of file
diff --git a/src/opentelemetry/proto/metrics/v1/metrics.proto b/src/opentelemetry/proto/metrics/v1/metrics.proto
new file mode 100644
index 0000000..1580a9b
--- /dev/null
+++ b/src/opentelemetry/proto/metrics/v1/metrics.proto
@@ -0,0 +1,274 @@
+// Copyright 2019, 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.
+
+syntax = "proto3";
+
+package opentelemetry.proto.metrics.v1;
+
+import "google/protobuf/timestamp.proto";
+import "google/protobuf/wrappers.proto";
+import "resource/v1/resource.proto";
+
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.metrics.v1";
+option java_outer_classname = "MetricsProto";
+
+// Defines a Metric which has one or more timeseries.
+message Metric {
+  // The descriptor of the Metric.
+  MetricDescriptor metric_descriptor = 1;
+
+  // One or more timeseries for a single metric, where each timeseries has
+  // one or more points.
+  repeated TimeSeries timeseries = 2;
+
+  // The resource for the metric. If unset, it may be set to a default value
+  // provided for a sequence of messages in an RPC stream.
+  opentelemetry.proto.resource.v1.Resource resource = 3;
+}
+
+// Defines a metric type and its schema.
+message MetricDescriptor {
+  // The metric type, including its DNS name prefix. It must be unique.
+  string name = 1;
+
+  // A detailed description of the metric, which can be used in documentation.
+  string description = 2;
+
+  // The unit in which the metric value is reported. Follows the format
+  // described by http://unitsofmeasure.org/ucum.html.
+  string unit = 3;
+
+  // The kind of metric. It describes how the data is reported.
+  //
+  // A gauge is an instantaneous measurement of a value.
+  //
+  // A counter/cumulative measurement is a value accumulated over a time
+  // interval. In a time series, cumulative measurements should have the same
+  // start time, increasing values and increasing end times, until an event
+  // resets the cumulative value to zero and sets a new start time for the
+  // following points.
+  enum Type {
+    // Do not use this default value.
+    UNSPECIFIED = 0;
+
+    // Integer gauge. The value can go both up and down.
+    GAUGE_INT64 = 1;
+
+    // Floating point gauge. The value can go both up and down.
+    GAUGE_DOUBLE = 2;
+
+    // Histogram gauge measurement. The count and sum can go both up and
+    // down. Recorded values are always >= 0.
+    // Used in scenarios like a snapshot of time the current items in a queue
+    // have spent there.
+    GAUGE_HISTOGRAM = 3;
+
+    // Integer counter measurement. The value cannot decrease, if resets
+    // then the start_time should also be reset.
+    COUNTER_INT64 = 4;
+
+    // Floating point counter measurement. The value cannot decrease, if
+    // resets then the start_time should also be reset. Recorded values are
+    // always >= 0.
+    COUNTER_DOUBLE = 5;
+
+    // Histogram cumulative measurement. The count and sum cannot decrease,
+    // if resets then the start_time should also be reset.
+    CUMULATIVE_HISTOGRAM = 6;
+
+    // Some frameworks implemented Histograms as a summary of observations
+    // (usually things like request durations and response sizes). While it
+    // also provides a total count of observations and a sum of all observed
+    // values, it calculates configurable percentiles over a sliding time
+    // window. This is not recommended, since it cannot be aggregated.
+    SUMMARY = 7;
+  }
+  Type type = 4;
+
+  // The label keys associated with the metric descriptor.
+  repeated LabelKey label_keys = 5;
+}
+
+// Defines a label key associated with a metric descriptor.
+message LabelKey {
+  // The key for the label.
+  string key = 1;
+
+  // A human-readable description of what this label key represents.
+  string description = 2;
+}
+
+// A collection of data points that describes the time-varying values
+// of a metric.
+message TimeSeries {
+  // The set of label values that uniquely identify this timeseries. Applies to
+  // all points. The order of label values must match that of label keys in the
+  // metric descriptor.
+  repeated LabelValue label_values = 1;
+
+  // The data points of this timeseries. Point.value type MUST match the
+  // MetricDescriptor.type.
+  repeated Point points = 2;
+}
+
+message LabelValue {
+  // The value for the label.
+  string value = 1;
+  // If false the value field is ignored and considered not set.
+  // This is used to differentiate a missing label from an empty string.
+  bool has_value = 2;
+}
+
+// A timestamped measurement.
+message Point {
+  // Must be present for counter/cumulative metrics. The time when the
+  // cumulative value was reset to zero. The cumulative value is over the time
+  // interval (start_timestamp, timestamp]. If not specified, the backend can
+  // use the previous recorded value.
+  google.protobuf.Timestamp start_timestamp = 1;
+
+  // The moment when this point was recorded.
+  // If not specified, the timestamp will be decided by the backend.
+  google.protobuf.Timestamp timestamp = 2;
+
+  // The actual point value.
+  oneof value {
+    // A 64-bit integer.
+    int64 int64_value = 3;
+
+    // A 64-bit double-precision floating-point number.
+    double double_value = 4;
+
+    // A histogram value.
+    HistogramValue histogram_value = 5;
+
+    // A summary value. This is not recommended, since it cannot be aggregated.
+    SummaryValue summary_value = 6;
+  }
+}
+
+// Histogram contains summary statistics for a population of values. It may
+// optionally contain the distribution of those values across a set of buckets.
+message HistogramValue {
+  // The number of values in the population. Must be non-negative. This value
+  // must equal the sum of the values in bucket_counts if a histogram is
+  // provided.
+  int64 count = 1;
+
+  // The sum of the values in the population. If count is zero then this field
+  // must be zero.
+  double sum = 2;
+
+  // A Histogram may optionally contain the distribution of the values in the
+  // population. The bucket boundaries are described by BucketOptions.
+  message BucketOptions {
+    oneof type {
+      // Bucket with explicit bounds.
+      Explicit explicit = 1;
+    }
+
+    // Specifies a set of buckets with arbitrary upper-bounds.
+    // This defines size(bounds) + 1 (= N) buckets. The boundaries for bucket
+    // index i are:
+    //
+    // [0, bucket_bounds[i]) for i == 0
+    // [bucket_bounds[i-1], bucket_bounds[i]) for 0 < i < N-1
+    // [bucket_bounds[i], +infinity) for i == N-1
+    message Explicit {
+      // The values must be strictly increasing and > 0.
+      repeated double bounds = 1;
+    }
+
+    // TODO: If OpenMetrics decides to support (a, b] intervals we should add
+    // support for these by defining a boolean value here which decides what
+    // type of intervals to use.
+  }
+
+  // Don't change bucket boundaries within a TimeSeries if your backend doesn't
+  // support this.
+  BucketOptions bucket_options = 3;
+
+  message Bucket {
+    // The number of values in each bucket of the histogram, as described in
+    // bucket_bounds.
+    int64 count = 1;
+
+    // Exemplars are example points that may be used to annotate aggregated
+    // Histogram values. They are metadata that gives information about a
+    // particular value added to a Histogram bucket.
+    message Exemplar {
+      // Value of the exemplar point. It determines which bucket the exemplar
+      // belongs to.
+      double value = 1;
+
+      // The observation (sampling) time of the above value.
+      google.protobuf.Timestamp timestamp = 2;
+
+      // Contextual information about the example value.
+      map<string, string> attachments = 3;
+    }
+
+    // Exemplars are example points that may be used to annotate aggregated
+    // Histogram values.
+    Exemplar exemplar = 2;
+  }
+
+  // The sum of the values in the Bucket counts must equal the value in the
+  // count field of the histogram.
+  repeated Bucket buckets = 4;
+}
+
+// The start_timestamp only applies to the count and sum in the SummaryValue.
+message SummaryValue {
+  // The total number of recorded values since start_time. Optional since
+  // some systems don't expose this.
+  google.protobuf.Int64Value count = 1;
+
+  // The total sum of recorded values since start_time. Optional since some
+  // systems don't expose this. If count is zero then this field must be zero.
+  // This field must be unset if the sum is not available.
+  google.protobuf.DoubleValue sum = 2;
+
+  // The values in this message can be reset at arbitrary unknown times, with
+  // the requirement that all of them are reset at the same time.
+  message Snapshot {
+    // The number of values in the snapshot. Optional since some systems don't
+    // expose this.
+    google.protobuf.Int64Value count = 1;
+
+    // The sum of values in the snapshot. Optional since some systems don't
+    // expose this. If count is zero then this field must be zero or not set
+    // (if not supported).
+    google.protobuf.DoubleValue sum = 2;
+
+    // Represents the value at a given percentile of a distribution.
+    message ValueAtPercentile {
+      // The percentile of a distribution. Must be in the interval
+      // (0.0, 100.0].
+      double percentile = 1;
+
+      // The value at the given percentile of a distribution.
+      double value = 2;
+    }
+
+    // A list of values at different percentiles of the distribution calculated
+    // from the current snapshot. The percentiles must be strictly increasing.
+    repeated ValueAtPercentile percentile_values = 3;
+  }
+
+  // Values calculated over an arbitrary time window.
+  Snapshot snapshot = 3;
+}
+
diff --git a/src/opentelemetry/proto/resource/v1/resource.proto b/src/opentelemetry/proto/resource/v1/resource.proto
new file mode 100644
index 0000000..2200208
--- /dev/null
+++ b/src/opentelemetry/proto/resource/v1/resource.proto
@@ -0,0 +1,27 @@
+// Copyright 2019, 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.
+
+syntax = "proto3";
+
+package opentelemetry.proto.resource.v1;
+
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.resource.v1";
+option java_outer_classname = "ResourceProto";
+
+// Resource information.
+message Resource {
+  // Set of labels that describe the resource.
+  map<string,string> labels = 1;
+}
diff --git a/src/opentelemetry/proto/trace/v1/trace.proto b/src/opentelemetry/proto/trace/v1/trace.proto
new file mode 100644
index 0000000..3a586da
--- /dev/null
+++ b/src/opentelemetry/proto/trace/v1/trace.proto
@@ -0,0 +1,294 @@
+// Copyright 2019, 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.
+
+syntax = "proto3";
+
+package opentelemetry.proto.trace.v1;
+
+import "google/protobuf/timestamp.proto";
+import "google/protobuf/wrappers.proto";
+import "resource/v1/resource.proto";
+
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.trace.v1";
+option java_outer_classname = "TraceProto";
+
+// A span represents a single operation within a trace. Spans can be
+// nested to form a trace tree. Spans may also be linked to other spans
+// from the same or different trace. And form graphs. Often, a trace
+// contains a root span that describes the end-to-end latency, and one
+// or more subspans for its sub-operations. A trace can also contain
+// multiple root spans, or none at all. Spans do not need to be
+// contiguous - there may be gaps or overlaps between spans in a trace.
+//
+// The next id is 16.
+message Span {
+  // A unique identifier for a trace. All spans from the same trace share
+  // the same `trace_id`. The ID is a 16-byte array. An ID with all zeroes
+  // is considered invalid.
+  //
+  // This field is semantically required. Receiver should generate new
+  // random trace_id if empty or invalid trace_id was received.
+  //
+  // This field is required.
+  bytes trace_id = 1;
+
+  // A unique identifier for a span within a trace, assigned when the span
+  // is created. The ID is an 8-byte array. An ID with all zeroes is considered
+  // invalid.
+  //
+  // This field is semantically required. Receiver should generate new
+  // random span_id if empty or invalid span_id was received.
+  //
+  // This field is required.
+  bytes span_id = 2;
+
+  // This field conveys information about request position in multiple distributed tracing graphs.
+  // It is a list of Tracestate.Entry with a maximum of 32 members in the list.
+  //
+  // See the https://github.com/w3c/distributed-tracing for more details about this field.
+  message Tracestate {
+    message Entry {
+      // The key must begin with a lowercase letter, and can only contain
+      // lowercase letters 'a'-'z', digits '0'-'9', underscores '_', dashes
+      // '-', asterisks '*', and forward slashes '/'.
+      string key = 1;
+
+      // The value is opaque string up to 256 characters printable ASCII
+      // RFC0020 characters (i.e., the range 0x20 to 0x7E) except ',' and '='.
+      // Note that this also excludes tabs, newlines, carriage returns, etc.
+      string value = 2;
+    }
+
+    // A list of entries that represent the Tracestate.
+    repeated Entry entries = 1;
+  }
+
+  // The Tracestate on the span.
+  Tracestate tracestate = 3;
+
+  // The `span_id` of this span's parent span. If this is a root span, then this
+  // field must be empty. The ID is an 8-byte array.
+  bytes parent_span_id = 4;
+
+  // An optional resource that is associated with this span. If not set, this span
+  // should be part of a batch that does include the resource information, unless resource
+  // information is unknown.
+  opentelemetry.proto.resource.v1.Resource resource = 5;
+
+  // A description of the span's operation.
+  //
+  // For example, the name can be a qualified method name or a file name
+  // and a line number where the operation is called. A best practice is to use
+  // the same display name at the same call point in an application.
+  // This makes it easier to correlate spans in different traces.
+  //
+  // This field is semantically required to be set to non-empty string.
+  // When null or empty string received - receiver may use string "name"
+  // as a replacement. There might be smarted algorithms implemented by
+  // receiver to fix the empty span name.
+  //
+  // This field is required.
+  TruncatableString name = 6;
+
+  // Type of span. Can be used to specify additional relationships between spans
+  // in addition to a parent/child relationship.
+  enum SpanKind {
+    // Unspecified.
+    SPAN_KIND_UNSPECIFIED = 0;
+
+    // Indicates that the span covers server-side handling of an RPC or other
+    // remote network request.
+    SERVER = 1;
+
+    // Indicates that the span covers the client-side wrapper around an RPC or
+    // other remote request.
+    CLIENT = 2;
+  }
+
+  // Distinguishes between spans generated in a particular context. For example,
+  // two spans with the same name may be distinguished using `CLIENT` (caller)
+  // and `SERVER` (callee) to identify queueing latency associated with the span.
+  SpanKind kind = 7;
+
+  // The start time of the span. On the client side, this is the time kept by
+  // the local machine where the span execution starts. On the server side, this
+  // is the time when the server's application handler starts running.
+  //
+  // This field is semantically required. When not set on receive -
+  // receiver should set it to the value of end_time field if it was
+  // set. Or to the current time if neither was set. It is important to
+  // keep end_time > start_time for consistency.
+  //
+  // This field is required.
+  google.protobuf.Timestamp start_time = 8;
+
+  // The end time of the span. On the client side, this is the time kept by
+  // the local machine where the span execution ends. On the server side, this
+  // is the time when the server application handler stops running.
+  //
+  // This field is semantically required. When not set on receive -
+  // receiver should set it to start_time value. It is important to
+  // keep end_time > start_time for consistency.
+  //
+  // This field is required.
+  google.protobuf.Timestamp end_time = 9;
+
+  // A set of attributes, each with a key and a value.
+  message Attributes {
+    // The set of attributes. The value can be a string, an integer, a double
+    // or the Boolean values `true` or `false`. Note, global attributes like 
+    // server name can be set as tags using resource API. Examples of attributes:
+    //
+    //     "/http/user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36"
+    //     "/http/server_latency": 300
+    //     "abc.com/myattribute": true
+    //     "abc.com/score": 10.239
+    map<string, AttributeValue> attribute_map = 1;
+
+    // The number of attributes that were discarded. Attributes can be discarded
+    // because their keys are too long or because there are too many attributes.
+    // If this value is 0, then no attributes were dropped.
+    int32 dropped_attributes_count = 2;
+  }
+
+  // A set of attributes on the span.
+  Attributes attributes = 10;
+
+
+  // A time-stamped event in the Span.
+  message TimedEvent {
+    // The time the event occurred.
+    google.protobuf.Timestamp time = 1;
+
+    // A text annotation with a set of attributes.
+    message Event {
+      // A user-supplied name describing the event.
+      TruncatableString name = 1;
+
+      // A set of attributes on the event.
+      Attributes attributes = 2;
+    }
+
+    // The event.
+    Event event = 2;
+  }
+
+  // A collection of `TimeEvent`s. A `TimeEvent` is a time-stamped annotation
+  // on the span, consisting of either user-supplied key-value pairs, or
+  // details of a message sent/received between Spans.
+  message TimedEvents {
+    // A collection of `TimedEvent`s.
+    repeated TimedEvent timed_event = 1;
+
+    // The number of dropped timed events. If the value is 0, then no events were dropped.
+    int32 dropped_timed_events_count = 2;
+  }
+
+  // The included timed events.
+  TimedEvents time_events = 11;
+
+  // A pointer from the current span to another span in the same trace or in a
+  // different trace. For example, this can be used in batching operations,
+  // where a single batch handler processes multiple requests from different
+  // traces or when the handler receives a request from a different project.
+  message Link {
+    // A unique identifier of a trace that this linked span is part of. The ID is a 
+    // 16-byte array.
+    bytes trace_id = 1;
+
+    // A unique identifier for the linked span. The ID is an 8-byte array.
+    bytes span_id = 2;
+
+    // The Tracestate associated with the link.
+    Tracestate tracestate = 3;
+
+    // A set of attributes on the link.
+    Attributes attributes = 4;
+  }
+
+  // A collection of links, which are references from this span to a span
+  // in the same or different trace.
+  message Links {
+    // A collection of links.
+    repeated Link link = 1;
+
+    // The number of dropped links after the maximum size was enforced. If
+    // this value is 0, then no links were dropped.
+    int32 dropped_links_count = 2;
+  }
+
+  // The included links.
+  Links links = 12;
+
+  // An optional final status for this span. Semantically when Status
+  // wasn't set it is means span ended without errors and assume
+  // Status.Ok (code = 0).
+  Status status = 13;
+
+  // A highly recommended but not required flag that identifies when a
+  // trace crosses a process boundary. True when the parent_span belongs
+  // to the same process as the current span. This flag is most commonly
+  // used to indicate the need to adjust time as clocks in different
+  // processes may not be synchronized.
+  google.protobuf.BoolValue same_process_as_parent_span = 14;
+
+  // An optional number of child spans that were generated while this span
+  // was active. If set, allows an implementation to detect missing child spans.
+  google.protobuf.UInt32Value child_span_count = 15;
+}
+
+// The `Status` type defines a logical error model that is suitable for different
+// programming environments, including REST APIs and RPC APIs. This proto's fields
+// are a subset of those of
+// [google.rpc.Status](https://github.com/googleapis/googleapis/blob/master/google/rpc/status.proto),
+// which is used by [gRPC](https://github.com/grpc).
+message Status {
+  // The status code. This is optional field. It is safe to assume 0 (OK)
+  // when not set.
+  int32 code = 1;
+
+  // A developer-facing error message, which should be in English.
+  string message = 2;
+}
+
+// The value of an Attribute.
+message AttributeValue {
+  // The type of the value.
+  oneof value {
+    // A string up to 256 bytes long.
+    TruncatableString string_value = 1;
+    // A 64-bit signed integer.
+    int64 int_value = 2;
+    // A Boolean value represented by `true` or `false`.
+    bool bool_value = 3;
+    // A double value.
+    double double_value = 4;
+  }
+}
+
+// A string that might be shortened to a specified length.
+message TruncatableString {
+  // The shortened string. For example, if the original string was 500 bytes long and
+  // the limit of the string was 128 bytes, then this value contains the first 128
+  // bytes of the 500-byte string. Note that truncation always happens on a
+  // character boundary, to ensure that a truncated string is still valid UTF-8.
+  // Because it may contain multi-byte characters, the size of the truncated string
+  // may be less than the truncation limit.
+  string value = 1;
+
+  // The number of bytes removed from the original string. If this
+  // value is 0, then the string was not shortened.
+  int32 truncated_byte_count = 2;
+}
diff --git a/src/opentelemetry/proto/trace/v1/trace_config.proto b/src/opentelemetry/proto/trace/v1/trace_config.proto
new file mode 100644
index 0000000..467391c
--- /dev/null
+++ b/src/opentelemetry/proto/trace/v1/trace_config.proto
@@ -0,0 +1,77 @@
+// Copyright 2019, 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.
+
+syntax = "proto3";
+
+package opentelemetry.proto.trace.v1;
+
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.trace.v1";
+option java_outer_classname = "TraceConfigProto";
+
+// Global configuration of the trace service. All fields must be specified, or
+// the default (zero) values will be used for each type.
+message TraceConfig {
+
+  // The global default sampler used to make decisions on span sampling.
+  oneof sampler {
+    ConstantSampler constant_sampler = 1;
+
+    ProbabilitySampler probability_sampler = 2;
+
+    RateLimitingSampler rate_limiting_sampler = 3;
+  }
+
+  // The global default max number of attributes per span.
+  int64 max_number_of_attributes = 4;
+
+  // The global default max number of annotation events per span.
+  int64 max_number_of_timed_events= 5;
+
+  // The global default max number of attributes per timed event.
+  int64 max_number_of_attributes_per_timed_event = 6;
+
+  // The global default max number of link entries per span.
+  int64 max_number_of_links = 7;
+
+  // The global default max number of attributes per span.
+  int64 max_number_of_attributes_per_link = 8;
+}
+
+// Sampler that always makes a constant decision on span sampling.
+message ConstantSampler {
+  // How spans should be sampled:
+  // - Always off
+  // - Always on
+  // - Always follow the parent Span's decision (off if no parent).
+  enum ConstantDecision {
+    ALWAYS_OFF = 0;
+    ALWAYS_ON = 1;
+    ALWAYS_PARENT = 2;
+  }
+  ConstantDecision decision = 1;
+}
+
+// Sampler that tries to uniformly sample traces with a given probability.
+// The probability of sampling a trace is equal to that of the specified probability.
+message ProbabilitySampler {
+  // The desired probability of sampling. Must be within [0.0, 1.0].
+  double samplingProbability = 1;
+}
+
+// Sampler that tries to sample with a rate per time window.
+message RateLimitingSampler {
+  // Rate per second.
+  int64 qps = 1;
+}