Status

Current state: Under Discussion

Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]

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Motivation

3.0 gives us the opportunity to make backward-incompatible changes. With that, now is a good time to change the default serde from `byte array` to `null`. This change will allow users to better catch serialization issues from the beginning, as it's likely that they need to be setting a default serde themselves or passing in a serde rather than relying on the byte array default. 

Public Interfaces

Within `StreamsConfig.java`, DEFAULT_KEY_SERDE_CLASS_CONFIG will default to null and DEFAULT_VALUE_SERDE_CLASS_CONFIG will default to null. That means that the following existing methods will return `null` if no default is set, whereas before they returned byte array.

// Will return null if no default is set through configs
public Serde defaultKeySerde() {
}

// Will return null if no default is set through configs
 public Serde defaultValueSerde() {
}

Proposed Changes

Where the default key and value serde used to be a byte array, it will now be null. Instead of throwing Null Pointer Exceptions, we'll throw a Streams Exception to remind the user that they need to set a serde through the default configs or pass one in.

Compatibility, Deprecation, and Migration Plan

• Users who currently rely on the default serdes being a byte array will need to update their applications to manually set the default serdes to byte array before upgrading to 3.0

Rejected Alternatives