pip/pip-396.md

# PIP-396: Align WindowFunction's WindowContext with BaseContext

# Background knowledge

Pulsar Functions and Connectors provide a `BaseContext` object, enabling users to access the current execution environment, including logs, metrics, states, secrets, and other context-specific features.
The `WindowFunction`, designed to process multiple messages at once, offers a `WindowContext` object with similar functionality. However, `WindowContext` lacks certain features available in `BaseContext`.

# Motivation

Currently, the `WindowContext` interface does not include some critical methods provided by `BaseContext`, such as `getSecret` and `deleteState`. This limitation makes Window Functions feel less capable compared to standard Functions.

# Goals

## In Scope

- Enhance `WindowContext` by adding missing features from `BaseContext`.

## Out of Scope

# High-Level Design

The solution involves aligning `WindowContext` with `BaseContext` by extending the `WindowContext` interface and implementing missing methods in `WindowContextImpl`.

# Detailed Design

## Design & Implementation Details

Refer to implementation PR: https://github.com/apache/pulsar/pull/23628

The implementation strategy is straightforward:

- Update the `WindowContext` interface to extend the `BaseContext` interface.
- Remove duplicate method definitions in `WindowContext` already covered by `BaseContext`.
- Implement the following missing methods in the `WindowContextImpl` class:

```java
@Override
public String getSecret(String secretName) {
    return this.context.getSecret(secretName);
}

@Override
public CompletableFuture<Void> incrCounterAsync(String key, long amount) {
    return this.context.incrCounterAsync(key, amount);
}

@Override
public CompletableFuture<Long> getCounterAsync(String key) {
    return this.context.getCounterAsync(key);
}

@Override
public CompletableFuture<Void> putStateAsync(String key, ByteBuffer value) {
    return this.context.putStateAsync(key, value);
}

@Override
public CompletableFuture<ByteBuffer> getStateAsync(String key) {
    return this.context.getStateAsync(key);
}

@Override
public void deleteState(String key) {
    this.context.deleteState(key);
}

@Override
public CompletableFuture<Void> deleteStateAsync(String key) {
    return this.context.deleteStateAsync(key);
}

@Override
public void fatal(Throwable t) {
    this.context.fatal(t);
}
```

## Public-facing Changes

With this update, developers working on Window Functions can leverage the following new methods from WindowContext:

- getSecret
- incrCounterAsync
- getCounterAsync
- putStateAsync
- getStateAsync
- deleteState
- deleteStateAsync
- fatal

### Configuration

# Backward & Forward Compatibility

This update is fully backward-compatible. No existing methods in WindowContext are modified or removed, ensuring seamless integration with current implementations.