Examples

To view the full example take a look here.

Server example

Include required headers:

#include <stdio.h>
#include "japi.h"
#include "japi_pushsrv.h"
#include "japi_utils.h"

Register services and start server:

int main(int argc, char *argv[])
{
    int ret;
    japi_context *ctx;
    japi_pushsrv_context *psc_counter, *psc_temperature;

    /* Declare & initialise resources*/
    resources temperature_sensor = {17.0};

    /* Read port */
    if (argc != 2) {
        fprintf(stderr, "ERROR: Missing argument or wrong amount of arguments.\n" \
                "Usage:\n\t%s <port>\n", argv[0]);
        return -1;
    }

    /* Create JSON API context */
    ctx = japi_init(&temperature_sensor);
    if (ctx == NULL) {
        fprintf(stderr, "ERROR: Failed to create japi context\n");
        return -1;
    }

    /* Include request args in response */
    japi_include_args_in_response(ctx, true);

    /* Register JSON API requests */
    japi_register_request(ctx, "request_not_found_handler", &rnf_handler);
    japi_register_request(ctx, "get_temperature", &get_temperature);

    /* Register push services */
    psc_counter = japi_pushsrv_register(ctx, "push_counter");
    psc_temperature = japi_pushsrv_register(ctx, "push_temperature");

    /* Start push threads */
    japi_pushsrv_start(psc_counter, &push_counter);
    japi_pushsrv_start(psc_temperature, &push_temperature);

    /* Set maximal number of allowed clients. 0 for unlimited */
    japi_set_max_allowed_clients(ctx, 3);

    /* Provide JSON API interface via TCP */
    ret = japi_start_server(ctx, argv[1]);

    /* Destroy JAPI context */
    japi_destroy(ctx);

    return ret;
}

Client request example

#!/usr/bin/env python3

# Copyright (c) 2023 Fraunhofer IIS
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the “Software”), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.


import errno
import json
import socket
import select

def process_request(cmd_request,sock):
    json_cmd = json.dumps(cmd_request) + "\n"
    sock.sendall(json_cmd.encode())

    resp = sock.recv(4096)

    # Just dump if not empty
    if resp:
        print(json.dumps(json.loads(resp.decode("utf-8")), indent=4))

def main():
    IP = 'localhost'
    TCP_PORT = 1234
    counter = 0 # response counter

    try:
        sock = socket.create_connection((IP, TCP_PORT))
    except socket.error as e:
        if e.errno != errno.ECONNREFUSED:
            print("Exception was thrown. Message is %s" % (e))
            return 1
        print("A connection to '%s:%d' could not be established." %(IP, TCP_PORT))
        return 1
        
    cmd_request = {
    "japi_request": "get_temperature",
    "args": {"unit": "kelvin"},
    }
    push_service_request = {
    "japi_request": "japi_pushsrv_list",
    }
    push_temperature_request_subscr = {
    "japi_request": "japi_pushsrv_subscribe",
    "args": {"service": "push_temperature"},
    }
    push_temperature_request_unsubscr = {
    "japi_request": "japi_pushsrv_unsubscribe",
    "args": {"service": "push_temperature"},
    }

    process_request(cmd_request,sock)
    process_request(push_service_request,sock)
    process_request(push_temperature_request_subscr,sock)

    # get push service messages
    sock.settimeout(10)
    try:
        resp = sock.recv(4096)
        # Iterate line by line
        for n, line in enumerate(sock.makefile(), start=1):
            # Just dump if received message is not empty
            if line:
                jdata = json.loads(line)
                print(json.dumps(json.loads(line), indent=4))
    except:
        pass
    finally:
        pass

    process_request(push_temperature_request_unsubscr,sock)

    sock.close()

if __name__ == "__main__":
    main()