model_server.py

# (c) 2019 - 2024 Open Risk (https://www.openriskmanagement.com)
#
# openLGD is licensed under the Apache 2.0 license a copy of which is included
# in the source distribution of openLGD. This is notwithstanding any licenses of
# third-party software included in this distribution. You may not use this file except in
# compliance with the License.
#
# Unless required by applicable law or agreed to in writing, software distributed under
# the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
# either express or implied. See the License for the specific language governing permissions and
# limitations under the License.

""" This module provides a model server that has local access to distributed data sources

Each federated model server makes three endpoints available
1) GET localhost:/          API Root, indicating the server is live
2) GET localhost:/start     URL to get initial locally estimated parameters (cold start)
3) POST localhost:/update   URL to post current averaged parameters (warm start)
"""

import json
import signal
from urllib.parse import urlparse

from flask import Flask, jsonify, request

from lgdModel import lgdModel

app = Flask(__name__)


def start_calculation():
    url = urlparse(request.host)
    port = url.path.split(':')[-1]
    n = int(port) - 5000
    initial_params = lgdModel(server=n)
    return initial_params


def update_calculation(params):
    url = urlparse(request.host)
    port = url.path.split(':')[-1]
    n = int(port) - 5000
    intercept = params['intercept']
    coef = params['coefficient']
    updated_params = lgdModel(server=n, intercept=intercept, coef=coef)
    return updated_params


@app.route('/start', methods=['GET'])
def start():
    initial_params = start_calculation()
    return initial_params


@app.route('/update', methods=['POST'])
def update():
    print('Headers', request.headers)
    old_params = json.loads(request.data.decode('utf-8'))
    new_params = update_calculation(old_params)
    return new_params


@app.route('/stop', methods=['GET'])
def stop():
    sig = getattr(signal, "SIGKILL", signal.SIGTERM)
    # os.kill(os.getpid(), sig)
    # os.kill(os.getpid(), signal.SIGINT)
    func = request.environ.get('werkzeug.server.shutdown')
    func()
    return jsonify({"success": True, "message": "Server is shutting down..."})


@app.route('/')
def hello_world():
    resp = {'message': 'Hello Federated Credit Risk Models!', 'from server': request.host}
    return resp


if __name__ == '__main__':
    app.run(debug=True)