Flow PHP

Carrier

Carrier for propagating context across process boundaries.

A carrier is the transport mechanism for context propagation headers. Implementations handle specific transport types (HTTP headers, gRPC metadata, message queue headers, etc.).

Example implementation for PSR-7:

final class Psr7Carrier implements Carrier
{
    public function __construct(private RequestInterface $request) }

    public function get(string $key): ?string
    {
        $values = $this->request->getHeader($key);
        return $values[0] ?? null;
    }

    public function set(string $key, string $value): void
    {
        $this->request = $this->request->withHeader($key, $value);
    }

}

Methods

get() : null|string: Get a value by key.
set() : void: Set a value.

get()

Get a value by key.


    public
                    get(string $key) : null|string

Key lookup should be case-insensitive for HTTP header compatibility.

Parameters

$key : string: The key to look up

Return values

null|string —

The value, or null if not found

set()

Set a value.


    public
                    set(string $key, string $value) : void

Parameters

$key : string: The key to set
$value : string: The value to set