Introduce model translation and encoding interfaces

protocols/encodings/decoder.go

@@ -0,0 +1,35 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package encodings
+
+import "go.opentelemetry.io/collector/consumer/pdata"
+
+// MetricsDecoder converts another protocol to pdata.
+type MetricsDecoder interface {
+	// UnmarshalMetrics converts data in another protocol to pdata.
+	UnmarshalMetrics(bytes []byte) (pdata.Metrics, error)
+}
+
+// TracesDecoder converts another type of data to pdata.
+type TracesDecoder interface {
+	// UnmarshalTraces converts data in another protocol to pdata.
+	UnmarshalTraces(bytes []byte) (pdata.Traces, error)
+}
+
+// LogsDecoder converts another type of data to pdata.
+type LogsDecoder interface {
+	// UnmarshalLogs converts a data model of another protocol into pdata.
+	UnmarshalLogs(bytes []byte) (pdata.Logs, error)
+}

protocols/encodings/encoder.go

@@ -0,0 +1,32 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package encodings
+
+import "go.opentelemetry.io/collector/consumer/pdata"
+
+// MetricsEncoder converts pdata to another type.
+type MetricsEncoder interface {
+	MarshalMetrics(md pdata.Metrics) ([]byte, error)
+}
+
+// TracesEncoder converts pdata to another type.
+type TracesEncoder interface {
+	MarshalTraces(md pdata.Traces) ([]byte, error)
+}
+
+// LogsEncoder converts pdata to another type.
+type LogsEncoder interface {
+	MarshalLogs(md pdata.Logs) ([]byte, error)
+}

protocols/encodings/encodings.go

@@ -0,0 +1,38 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package encodings
+
+import "fmt"
+
+// Encoding is the format that a protocol is serialized to.
+type Encoding string
+
+const (
+	Protobuf Encoding = "protobuf"
+	JSON     Encoding = "json"
+	Thrift   Encoding = "thrift"
+)
+
+func (e Encoding) String() string {
+	return string(e)
+}
+
+type ErrInvalidEncoding struct {
+	Encoding Encoding
+}
+
+func (e *ErrInvalidEncoding) Error() string {
+	return fmt.Sprintf("unsupported encoding %q", e.Encoding)
+}

protocols/models/models.go

@@ -0,0 +1,51 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package models
+
+import (
+	"fmt"
+	"go.opentelemetry.io/collector/consumer/pdata"
+)
+
+type MetricsModelTranslator interface {
+	// MetricsFromModel converts a data model of another protocol into pdata.
+	MetricsFromModel(src interface{}) (pdata.Metrics, error)
+	// MetricsToModel converts pdata to data model.
+	MetricsToModel(md pdata.Metrics, out interface{}) error
+}
+
+type TracesModelTranslator interface {
+	// TracesFromModel converts a data model of another protocol into pdata.
+	TracesFromModel(src interface{}) (pdata.Traces, error)
+	// TracesToModel converts pdata to data model.
+	TracesToModel(md pdata.Traces, out interface{}) error
+}
+
+type LogsModelTranslator interface {
+	// LogsFromModel converts a data model of another protocol into pdata.
+	LogsFromModel(src interface{}) (pdata.Logs, error)
+	// LogsToModel converts pdata to data model.
+	LogsToModel(md pdata.Logs, out interface{}) error
+}
+
+// ErrIncompatibleType details a type conversion error during translation.
+type ErrIncompatibleType struct {
+	Model interface{}
+	// TODO: maybe do expected vs. actual?
+}
+
+func (i *ErrIncompatibleType) Error() string {
+	return fmt.Sprintf("model type %T is incompatible", i.Model)
+}

protocols/zipkinv2/encodings.go

@@ -0,0 +1,71 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package zipkinv2
+
+import (
+	"encoding/json"
+
+	zipkinmodel "github.com/openzipkin/zipkin-go/model"
+	"github.com/openzipkin/zipkin-go/proto/zipkin_proto3"
+
+	"go.opentelemetry.io/collector/consumer/pdata"
+	"go.opentelemetry.io/collector/protocols/encodings"
+	"go.opentelemetry.io/collector/protocols/models"
+)
+
+var (
+	_ encodings.TracesEncoder = (*Encoder)(nil)
+	_ encodings.TracesDecoder = (*Encoder)(nil)
+)
+
+type Encoder struct {
+	models.TracesModelTranslator
+	// Encoding is the format Zipkin is serialized to.
+	Encoding encodings.Encoding
+}
+
+func (z *Encoder) UnmarshalTraces(bytes []byte) (pdata.Traces, error) {
+	switch z.Encoding {
+	case encodings.Protobuf:
+		spans, err := zipkin_proto3.ParseSpans(bytes, false)
+		if err != nil {
+			return pdata.NewTraces(), err
+		}
+		return z.TracesFromModel(spans)
+	case encodings.JSON:
+		var spans []*zipkinmodel.SpanModel
+		if err := json.Unmarshal(bytes, &spans); err != nil {
+			return pdata.NewTraces(), err
+		}
+		return z.TracesFromModel(spans)
+	default:
+		return pdata.NewTraces(), &encodings.ErrInvalidEncoding{Encoding: z.Encoding}
+	}
+}
+
+func (z *Encoder) MarshalTraces(td pdata.Traces) ([]byte, error) {
+	switch z.Encoding {
+	// TODO
+	// case protocols.Protobuf:
+	case encodings.JSON:
+		var spans []*zipkinmodel.SpanModel
+		if err := z.TracesToModel(td, &spans); err != nil {
+			return nil, err
+		}
+		return json.Marshal(spans)
+	default:
+		return nil, &encodings.ErrInvalidEncoding{Encoding: z.Encoding}
+	}
+}

protocols/zipkinv2/models.go

@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package zipkinv2
+
+import (
+	zipkinmodel "github.com/openzipkin/zipkin-go/model"
+
+	"go.opentelemetry.io/collector/consumer/pdata"
+	"go.opentelemetry.io/collector/protocols/models"
+	"go.opentelemetry.io/collector/translator/trace/zipkin"
+)
+
+var (
+	_ models.TracesModelTranslator = (*Model)(nil)
+)
+
+type Model struct {
+	// ParseStringTags is true if string tags should be automatically converted to numbers.
+	ParseStringTags bool
+}
+
+func (z *Model) TracesFromModel(src interface{}) (pdata.Traces, error) {
+	if model, ok := src.([]*zipkinmodel.SpanModel); ok {
+		return zipkin.V2SpansToInternalTraces(model, z.ParseStringTags)
+	}
+	return pdata.NewTraces(), &models.ErrIncompatibleType{Model: src}
+}
+
+func (z *Model) TracesToModel(td pdata.Traces, out interface{}) error {
+	if model, ok := out.(*[]*zipkinmodel.SpanModel); ok {
+		sm, err := zipkin.InternalTracesToZipkinSpans(td)
+		if err != nil {
+			return err
+		}
+		*model = sm
+	}
+	return &models.ErrIncompatibleType{Model: out}
+}