journal-gateway-client 0.8.0

Python client library for the Journal Gateway protocol

journal-gateway-client

Python service-side library for the Journal Gateway protocol. Use this package in the service that accepts gateway WebSocket connections, validates gateway tokens, receives tool and skill catalogs, and calls tools on connected gateways.

If you want to run the customer-side gateway process, install the npm package journal-gateway instead.

Install

Requires Python 3.11 or newer.

pip install journal-gateway-client

Quick Start

import asyncio
import os

from journal_gateway_client import GatewayServer, TokenValidationResult


async def validate_token(token: str) -> TokenValidationResult | None:
    if token == os.environ["JOURNAL_GATEWAY_TOKEN"]:
        return TokenValidationResult(organization_id="org_123")
    return None


async def main() -> None:
    server = GatewayServer(validate_token=validate_token, port=8080)

    server.on_gateway_connected = lambda gateway: print(
        "gateway connected", gateway.id, gateway.organization_id
    )
    server.on_gateway_updated = lambda gateway: print(
        "gateway catalog updated", gateway.id
    )
    server.on_gateway_disconnected = lambda gateway: print(
        "gateway disconnected", gateway.id
    )

    await server.start()

    # After a gateway for org_123 connects and publishes the postgresql integration:
    result = await server.call_tool_for_org(
        "org_123",
        "postgresql",
        "execute_sql",
        {"sql": "SELECT 1"},
    )
    print(result.content)

    await server.stop()


asyncio.run(main())

The library never prints to stdout by itself. Route callbacks into your own logger, metrics, and tracing stack. If on_socket_error is not provided, unexpected socket errors go to the journal_gateway_client logger, which is silent by default unless your application configures logging.

Key APIs

• start() / stop(): start or stop the WebSocket server.
• call_tool(integration_id, tool_name, arguments, timeout=60.0): call a tool on any connected gateway that exposes the integration.
• call_tool_for_org(organization_id, integration_id, tool_name, arguments, timeout=90.0): call a tool for one organization, with candidate gateway selection and retry on connection-level failure.
• get_tools_for_org(organization_id): list deduplicated tools for an organization.
• get_versions(gateway_id), get_tools(gateway_id), get_skills(gateway_id): explicitly pull catalog data from a specific gateway.
• connected_gateways: inspect currently connected gateways.

Callbacks

Set these attributes on the server instance:

• on_gateway_connected(gateway): fired after authentication and initial catalog pull.
• on_gateway_updated(gateway): fired when MCP tools or skills change.
• on_gateway_disconnected(gateway): fired after a connected gateway disconnects.

Constructor callbacks:

• get_trace_context: returns W3C trace context for each tool call.
• on_socket_error(error, gateway | None): receives socket-level failures such as connection resets.

Trace Propagation

from opentelemetry import propagate


def get_trace_context() -> dict[str, str] | None:
    carrier: dict[str, str] = {}
    propagate.inject(carrier)
    if "traceparent" not in carrier:
        return None
    return {
        "traceparent": carrier["traceparent"],
        "tracestate": carrier.get("tracestate"),
    }


def on_socket_error(error: Exception, gateway) -> None:
    logger.error(
        "gateway socket error",
        exc_info=error,
        extra={"gateway_id": gateway.id if gateway else None},
    )


server = GatewayServer(
    validate_token=validate_token,
    port=8080,
    get_trace_context=get_trace_context,
    on_socket_error=on_socket_error,
)

get_trace_context is called for each tool call. The returned W3C trace context is sent to the gateway and used as the parent for remote tool execution spans.

Version Compatibility

Journal Gateway packages release in lockstep. Use matching versions of:

• npm journal-gateway
• npm journal-gateway-client for TypeScript services
• npm journal-gateway-protocol
• PyPI journal-gateway-client for Python services

More Documentation

• Full README
• Protocol spec
• Gateway npm package

License

MIT