Class KVCoder<K, V>

Decode the input byte stream into a KV element.

Returns

the decoded element into a KV-typed object.

Encode the input element (a key-value pair) into a byte output stream. They key and value are encoded one after the other (first key, then value). The key is encoded with Context.needsDelimiters, while the value is encoded with the input context of the KVCoder.

For example:

let w1 = new Writer()
let data = {'key': 'k1', 'value': 'v1'}
new KVCoder(new StrUtf8Coder(), new StrUtf8Coder()).encode(data, w1, Context.needsDelimiters)
console.log(w1.finish())  // ==> prints  Uint8Array(6) [ 2, 107, 49, 2, 118, 49 ]
// Note that bytes with value 2 represent length prefixes, and other bytes represent the encoded strings.

Convert this coder into its protocol buffer representation for the Runner API. A coder in protobuf format can be shared with other components such as Beam runners, SDK workers; and reconstructed into its runtime representation if necessary.