Trait SessionKeyExtractor 

pub trait SessionKeyExtractor {
    // Required method
    fn get_metadata(&self, key: &str) -> Option<String>;

    // Provided methods
    fn list_metadata_keys(&self) -> Vec<String> { ... }
    fn get_all_metadata(&self) -> HashMap<String, String> { ... }
}

Trait for extracting metadata from messages for session key generation.

This trait provides a completely generic interface for messages to expose metadata that can be used to generate session keys. It makes no assumptions about the message structure or domain.

Design

The trait uses a key-value interface where messages expose named metadata fields. Session key generators query for the metadata they need.

Example

use queue_runtime::sessions::SessionKeyExtractor;

struct MyMessage {
    user_id: String,
    resource_id: String,
}

impl SessionKeyExtractor for MyMessage {
    fn get_metadata(&self, key: &str) -> Option<String> {
        match key {
            "user_id" => Some(self.user_id.clone()),
            "resource_id" => Some(self.resource_id.clone()),
            _ => None,
        }
    }

    fn list_metadata_keys(&self) -> Vec<String> {
        vec!["user_id".to_string(), "resource_id".to_string()]
    }
}

Required Methods

fn get_metadata(&self, key: &str) -> Option<String>

Get a metadata value by key.

Returns None if the key doesn’t exist or has no value for this message.

Arguments

• key - The metadata key to retrieve

Returns

Optional string value for the requested key

Provided Methods

fn list_metadata_keys(&self) -> Vec<String>

List all available metadata keys for this message.

This is useful for debugging and introspection. Default implementation returns an empty list.

Returns

Vector of available metadata key names

fn get_all_metadata(&self) -> HashMap<String, String>

Get all metadata as a map (optional, for bulk operations).

Default implementation iterates over list_metadata_keys() and calls get_metadata() for each key.

Returns

HashMap of all available metadata

Implementors