Keyed Opaque Format

When applications require efficient opaque messages, and also require content matching, you can use the keyed opaque built-in format. Keyed opaque messages are optimized: though less efficient than the opaque built-in format, they are more efficient than an equivalent managed format.

Applications can use content matchers to match against the key field.

To optimize performance, built-in opaque formats limit the combined size of the data payload and the key. If you need to send larger payloads, define a static format with an opaque field and a string key field.