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Content Transfer Encodings

Encode event payloads for safe transport over text-based protocols.

Overview

Content transfer encodings transform binary data into a text-safe representation. They're optional — without a content transfer encoding, the payload is sent as-is.

Content transfer encoding runs after both serialization and content encoding.

Supported Destinations

Encodings are applied by the destinations that carry an opaque payload over HTTP-style or SDK transports: http, soap, grpc, aws-eventbridge, aws-sns, aws-sqs, azure-eventgrid, azure-storage-queue, azure-webpubsub and gcp-cloud-tasks. All other destinations accept the property but do not apply it (the payload is sent unencoded).

Available Content Transfer Encodings

Encoding Config Description
Base64 base64 RFC 4648 Base64 encoding

Quick Example

Base64 encode for text-only transports: 

kete.routes.encoded.destination.content-transfer-encoding=base64

When to Use

Content transfer encoding is useful when:

  • The destination only accepts text (e.g., AWS SQS message bodies)
  • You're using a binary serializer (Protobuf, Avro, CBOR) over a text-based protocol
  • You're combining with content encoding (gzip + base64)

Processing Order

The encoding pipeline runs in this order:

  1. Serialization — event → bytes (e.g., JSON, Protobuf)
  2. Content Encoding — compress bytes (e.g., gzip)
  3. Content Transfer Encoding — encode bytes (e.g., base64)

See Also