sdk-go/v1/bindings/amqp/message.go

115 lines
2.9 KiB
Go

package amqp
import (
"bytes"
"context"
"errors"
"reflect"
"strings"
"pack.ag/amqp"
"github.com/cloudevents/sdk-go/v1/binding"
"github.com/cloudevents/sdk-go/v1/binding/format"
"github.com/cloudevents/sdk-go/v1/binding/spec"
)
const prefix = "cloudEvents:" // Name prefix for AMQP properties that hold CE attributes.
var (
// Use the package path as AMQP error condition name
condition = amqp.ErrorCondition(reflect.TypeOf(Message{}).PkgPath())
specs = spec.WithPrefix(prefix)
)
// Message implements binding.Message by wrapping an *amqp.Message.
type Message struct {
AMQP *amqp.Message
encoding binding.Encoding
}
func NewMessage(message *amqp.Message) *Message {
if message.Properties != nil && format.IsFormat(message.Properties.ContentType) {
return &Message{AMQP: message, encoding: binding.EncodingStructured}
} else if _, err := specs.FindVersion(func(k string) string {
s, _ := message.ApplicationProperties[k].(string)
return s
}); err == nil {
return &Message{AMQP: message, encoding: binding.EncodingBinary}
} else {
return &Message{AMQP: message, encoding: binding.EncodingUnknown}
}
}
// Check if amqp.Message implements binding.Message
var _ binding.Message = (*Message)(nil)
func (m *Message) Encoding() binding.Encoding {
return m.encoding
}
func (m *Message) Structured(ctx context.Context, encoder binding.StructuredEncoder) error {
if m.AMQP.Properties != nil && format.IsFormat(m.AMQP.Properties.ContentType) {
return encoder.SetStructuredEvent(ctx, format.Lookup(m.AMQP.Properties.ContentType), bytes.NewReader(m.AMQP.GetData()))
}
return binding.ErrNotStructured
}
func (m *Message) Binary(ctx context.Context, encoder binding.BinaryEncoder) error {
if len(m.AMQP.ApplicationProperties) == 0 {
return errors.New("AMQP CloudEvents message has no application properties")
}
version, err := specs.FindVersion(func(k string) string {
s, _ := m.AMQP.ApplicationProperties[k].(string)
return s
})
if err != nil {
return err
}
err = encoder.Start(ctx)
if err != nil {
return err
}
if m.AMQP.Properties != nil && m.AMQP.Properties.ContentType != "" {
err = encoder.SetAttribute(version.AttributeFromKind(spec.DataContentType), m.AMQP.Properties.ContentType)
if err != nil {
return err
}
}
for k, v := range m.AMQP.ApplicationProperties {
if strings.HasPrefix(k, prefix) {
attr := version.Attribute(k)
if attr != nil {
err = encoder.SetAttribute(attr, v)
} else {
err = encoder.SetExtension(strings.ToLower(strings.TrimPrefix(k, prefix)), v)
}
}
if err != nil {
return err
}
}
data := m.AMQP.GetData()
if len(data) != 0 { // Some data
err = encoder.SetData(bytes.NewReader(data))
if err != nil {
return err
}
}
return encoder.End()
}
func (m *Message) Finish(err error) error {
if err != nil {
return m.AMQP.Reject(&amqp.Error{
Condition: condition,
Description: err.Error(),
})
}
return m.AMQP.Accept()
}