issue 814 - Add binary content mode for NATS and JetStream protocols

Signed-off-by: stephen-totty-hpe <stephen.totty@hpe.com>

.github/workflows/integration.yaml

@@ -32,6 +32,13 @@ jobs:
         ports:
           - 4222:4222
 
+      jetstream:
+        image: bitnami/nats:latest
+        env: 
+          NATS_EXTRA_ARGS: "--jetstream --port 4223"
+        ports:
+          - 4223:4223
+
       amqp:
         image: scholzj/qpid-dispatch
         env:

protocol/nats_jetstream/v2/message.go

@@ -8,13 +8,24 @@ package nats_jetstream
 import (
 	"bytes"
 	"context"
+	"fmt"
+	"strings"
 
 	"github.com/nats-io/nats.go"
 
 	"github.com/cloudevents/sdk-go/v2/binding"
 	"github.com/cloudevents/sdk-go/v2/binding/format"
+	"github.com/cloudevents/sdk-go/v2/binding/spec"
 )
 
+const (
+	// see https://github.com/cloudevents/spec/blob/main/cloudevents/bindings/nats-protocol-binding.md
+	prefix            = "ce-"
+	contentTypeHeader = "content-type"
+)
+
+var specs = spec.WithPrefix(prefix)
+
 // Message implements binding.Message by wrapping an *nats.Msg.
 // This message *can* be read several times safely
 type Message struct {
@@ -24,8 +35,15 @@ type Message struct {
 
 // NewMessage wraps an *nats.Msg in a binding.Message.
 // The returned message *can* be read several times safely
+// The default encoding returned is EncodingStructured unless the NATS message contains a specversion header.
 func NewMessage(msg *nats.Msg) *Message {
-	return &Message{Msg: msg, encoding: binding.EncodingStructured}
+	encoding := binding.EncodingStructured
+	if msg.Header != nil {
+		if msg.Header.Get(specs.PrefixedSpecVersionName()) != "" {
+			encoding = binding.EncodingBinary
+		}
+	}
+	return &Message{Msg: msg, encoding: encoding}
 }
 
 var _ binding.Message = (*Message)(nil)
@@ -37,15 +55,91 @@ func (m *Message) ReadEncoding() binding.Encoding {
 
 // ReadStructured transfers a structured-mode event to a StructuredWriter.
 func (m *Message) ReadStructured(ctx context.Context, encoder binding.StructuredWriter) error {
+	if m.encoding != binding.EncodingStructured {
+		return binding.ErrNotStructured
+	}
 	return encoder.SetStructuredEvent(ctx, format.JSON, bytes.NewReader(m.Msg.Data))
 }
 
 // ReadBinary transfers a binary-mode event to an BinaryWriter.
 func (m *Message) ReadBinary(ctx context.Context, encoder binding.BinaryWriter) error {
-	return binding.ErrNotBinary
+	if m.encoding != binding.EncodingBinary {
+		return binding.ErrNotBinary
+	}
+
+	version := m.GetVersion()
+	if version == nil {
+		return binding.ErrNotBinary
+	}
+
+	var err error
+	for k, v := range m.Msg.Header {
+		headerValue := v[0]
+		if strings.HasPrefix(k, prefix) {
+			attr := version.Attribute(k)
+			if attr != nil {
+				err = encoder.SetAttribute(attr, headerValue)
+			} else {
+				err = encoder.SetExtension(strings.TrimPrefix(k, prefix), headerValue)
+			}
+		} else if k == contentTypeHeader {
+			err = encoder.SetAttribute(version.AttributeFromKind(spec.DataContentType), headerValue)
+		}
+		if err != nil {
+			return err
+		}
+	}
+
+	if m.Msg.Data != nil {
+		err = encoder.SetData(bytes.NewBuffer(m.Msg.Data))
+	}
+
+	return err
 }
 
 // Finish *must* be called when message from a Receiver can be forgotten by the receiver.
 func (m *Message) Finish(err error) error {
 	return nil
 }
+
+// GetAttribute implements binding.MessageMetadataReader
+func (m *Message) GetAttribute(attributeKind spec.Kind) (spec.Attribute, interface{}) {
+	key := withPrefix(attributeKind.String())
+	if m.Msg.Header != nil {
+		headerValue := m.Msg.Header.Get(key)
+		if headerValue != "" {
+			version := m.GetVersion()
+			return version.Attribute(key), headerValue
+		}
+	}
+	return nil, nil
+}
+
+// GetExtension implements binding.MessageMetadataReader
+func (m *Message) GetExtension(name string) interface{} {
+	key := withPrefix(name)
+	if m.Msg.Header != nil {
+		headerValue := m.Msg.Header.Get(key)
+		if headerValue != "" {
+			return headerValue
+		}
+	}
+	return nil
+}
+
+// GetVersion looks for specVersion header and returns a Version object
+func (m *Message) GetVersion() spec.Version {
+	if m.Msg.Header == nil {
+		return nil
+	}
+	versionValue := m.Msg.Header.Get(specs.PrefixedSpecVersionName())
+	if versionValue == "" {
+		return nil
+	}
+	return specs.Version(versionValue)
+}
+
+// withPrefix prepends the prefix to the attribute name
+func withPrefix(attributeName string) string {
+	return fmt.Sprintf("%s%s", prefix, attributeName)
+}

protocol/nats_jetstream/v2/message_test.go

@@ -3,16 +3,21 @@ package nats_jetstream
 import (
 	"context"
 	"encoding/json"
-	bindingtest "github.com/cloudevents/sdk-go/v2/binding/test"
 	"testing"
 
+	"github.com/cloudevents/sdk-go/v2/binding/spec"
+	bindingtest "github.com/cloudevents/sdk-go/v2/binding/test"
+
 	"github.com/cloudevents/sdk-go/v2/binding"
 	"github.com/cloudevents/sdk-go/v2/test"
 	"github.com/nats-io/nats.go"
 )
 
 var (
-	outBinaryMessage = bindingtest.MockBinaryMessage{}
+	outBinaryMessage = bindingtest.MockBinaryMessage{
+		Metadata:   map[spec.Attribute]interface{}{},
+		Extensions: map[string]interface{}{},
+	}
 	outStructMessage = bindingtest.MockStructuredMessage{}
 
 	testEvent     = test.FullEvent()
@@ -31,18 +36,44 @@ var (
 		Subject: "hello",
 		Data:    binaryData,
 	}
+	binaryConsumerMessage = &nats.Msg{
+		Subject: "hello",
+		Data:    testEvent.Data(),
+		Header: nats.Header{
+			"ce-type":            {testEvent.Type()},
+			"ce-source":          {testEvent.Source()},
+			"ce-id":              {testEvent.ID()},
+			"ce-time":            {test.Timestamp.String()},
+			"ce-specversion":     {"1.0"},
+			"ce-dataschema":      {test.Schema.String()},
+			"ce-datacontenttype": {"text/json"},
+			"ce-subject":         {"receiverTopic"},
+			"ce-exta":            {"someext"},
+		},
+	}
 )
 
 func TestNewMessage(t *testing.T) {
 	tests := []struct {
-		name             string
-		consumerMessage  *nats.Msg
-		expectedEncoding binding.Encoding
+		name                    string
+		consumerMessage         *nats.Msg
+		expectedEncoding        binding.Encoding
+		expectedStructuredError error
+		expectedBinaryError     error
 	}{
 		{
-			name:             "Structured encoding",
-			consumerMessage:  structuredConsumerMessage,
-			expectedEncoding: binding.EncodingStructured,
+			name:                    "Structured encoding",
+			consumerMessage:         structuredConsumerMessage,
+			expectedEncoding:        binding.EncodingStructured,
+			expectedStructuredError: nil,
+			expectedBinaryError:     binding.ErrNotBinary,
+		},
+		{
+			name:                    "Binary encoding",
+			consumerMessage:         binaryConsumerMessage,
+			expectedEncoding:        binding.EncodingBinary,
+			expectedStructuredError: binding.ErrNotStructured,
+			expectedBinaryError:     nil,
 		},
 	}
 	for _, tt := range tests {
@@ -52,17 +83,16 @@ func TestNewMessage(t *testing.T) {
 				t.Errorf("Error in NewMessage!")
 			}
 			err := got.ReadBinary(context.TODO(), &outBinaryMessage)
-			if err == nil {
-				t.Errorf("Response in ReadBinary should err")
+			if err != tt.expectedBinaryError {
+				t.Errorf("ReadBinary err:%s", err.Error())
 			}
 			err = got.ReadStructured(context.TODO(), &outStructMessage)
-			if err != nil {
+			if err != tt.expectedStructuredError {
 				t.Errorf("ReadStructured err:%s", err.Error())
 			}
 			if got.ReadEncoding() != tt.expectedEncoding {
 				t.Errorf("ExpectedEncoding %s, while got %s", tt.expectedEncoding, got.ReadEncoding())
 			}
-
 		})
 	}
 }

protocol/nats_jetstream/v2/options.go

@@ -22,6 +22,20 @@ func NatsOptions(opts ...nats.Option) []nats.Option {
 // ProtocolOption is the function signature required to be considered an nats.ProtocolOption.
 type ProtocolOption func(*Protocol) error
 
+func WithConsumerOptions(opts ...ConsumerOption) ProtocolOption {
+	return func(p *Protocol) error {
+		p.consumerOptions = opts
+		return nil
+	}
+}
+
+func WithSenderOptions(opts ...SenderOption) ProtocolOption {
+	return func(p *Protocol) error {
+		p.senderOptions = opts
+		return nil
+	}
+}
+
 type SenderOption func(*Sender) error
 
 type ConsumerOption func(*Consumer) error

protocol/nats_jetstream/v2/protocol.go

@@ -7,6 +7,7 @@ package nats_jetstream
 
 import (
 	"context"
+
 	"github.com/cloudevents/sdk-go/v2/binding"
 	"github.com/cloudevents/sdk-go/v2/protocol"
 
@@ -18,11 +19,11 @@ import (
 type Protocol struct {
 	Conn *nats.Conn
 
-	Consumer *Consumer
-	//consumerOptions []ConsumerOption
+	Consumer        *Consumer
+	consumerOptions []ConsumerOption
 
-	Sender *Sender
-	//senderOptions []SenderOption
+	Sender        *Sender
+	senderOptions []SenderOption
 
 	connOwned bool // whether this protocol created the nats connection
 }
@@ -55,11 +56,11 @@ func NewProtocolFromConn(conn *nats.Conn, stream, sendSubject, receiveSubject st
 		return nil, err
 	}
 
-	if p.Consumer, err = NewConsumerFromConn(conn, stream, receiveSubject, jsOpts, subOpts); err != nil {
+	if p.Consumer, err = NewConsumerFromConn(conn, stream, receiveSubject, jsOpts, subOpts, p.consumerOptions...); err != nil {
 		return nil, err
 	}
 
-	if p.Sender, err = NewSenderFromConn(conn, stream, sendSubject, jsOpts); err != nil {
+	if p.Sender, err = NewSenderFromConn(conn, stream, sendSubject, jsOpts, p.senderOptions...); err != nil {
 		return nil, err
 	}
 

protocol/nats_jetstream/v2/sender.go

@@ -91,10 +91,18 @@ func (s *Sender) Send(ctx context.Context, in binding.Message, transformers ...b
 	}()
 
 	writer := new(bytes.Buffer)
-	if err = WriteMsg(ctx, in, writer, transformers...); err != nil {
+	header, err := WriteMsg(ctx, in, writer, transformers...)
+	if err != nil {
 		return err
 	}
-	_, err = s.Jsm.Publish(s.Subject, writer.Bytes())
+
+	natsMsg := &nats.Msg{
+		Subject: s.Subject,
+		Data:    writer.Bytes(),
+		Header:  header,
+	}
+
+	_, err = s.Jsm.PublishMsg(natsMsg)
 
 	return err
 }