Delivering Message

Last updated: 2020-09-01 15:42:19

    Queue Endpoint Subscription

    CMQ can publish the message text of a topic and deliver it to the subscribed queue, so consumers can read it from the queue.

    HTTP Endpoint Subscription

    Delivery description

    CMQ can push topic messages to the subscribed HTTP endpoint by sending POST requests. The message can be in JSON or SIMPLIFIED format.

    • JSON format: the body of the pushed HTTP request contains the message body and attribute information. The Content-type is text/plain.
    • SIMPLIFIED format: the body of the pushed HTTP request is the message body, while information such as msgId will be delivered to the subscriber in the HTTP request header.

    If the HTTP service of the subscriber returns a standard 2xx response code (such as 200), the delivery succeeded; otherwise, the delivery failed, and the delivery retry policy has been triggered. If no response is returned after the timeout period elapses, CMQ will also consider the request as a failure and trigger the delivery retry policy. The detection timeout period is about 15 seconds.

    Header of HTTP delivery request

    Parameter Name Description
    x-cmq-request-id requestId of the current push message
    x-cmq-message-id msgId of the current push message
    x-cmq-message-tag Tag of the current push message

    Body of HTTP delivery request

    The body of an HTTP request in JSON format contains the message body and attribute information.

    Parameter Name Type Description
    TopicOwner String APPID of the owner of the subscribed topic
    topicName String Topic name
    subscriptionName String Subscription name
    msgId String Message ID
    msgBody String Message body
    publishTime Int Message published time

    The body of an HTTP request in SIMPLIFIED format is the message body published by the publisher.

    Response of HTTP delivery request

    If a 2xx response code is returned, the HTTP service of the subscriber has normally processed the delivered message; if another response code is returned or no response is returned after the timeout period elapses, an error will be reported, and the delivery retry policy will be triggered.

    Sample request

    In this sample, the subscribed HTTP endpoint is http://test.com/cgi.
    JSON format:

    POST /cgi HTTP/1.1
    Host: test.com
    Content-Length: 761
    Content-Type: text/plain
    User-Agent: Qcloud Notification Service Agent
    x-cmq-request-id: 2394928734
    x-cmq-message-id: 6942316962
    x-cmq-message-tag: a, b
    
    {"TopicOwner":100015036,"topicName":"MyTopic","subscriptionName":"mysubscription","msgId":"6942316962","msgBody":"test message","publishTime":11203432}

    SIMPLIFIED format:

    POST /cgi HTTP/1.1
    Host: test.com
    Content-Length: 123
    Content-Type: text/plain
    User-Agent: Qcloud Notification Service Agent
    x-cmq-request-id: 2394928734
    x-cmq-message-id: 6942316962
    x-cmq-message-tag: a, b
    
    test message

    Sample message subscription

    The following is a message subscription demo, where all messages are delivered in the POST method; therefore, you only need to rewrite the do_POST method.
    This sample will print the received HTTP POST request content and deserialize post data json to traverse the printed request data.

    #!/usr/bin/python
    from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
    import json
    class TestHTTPHandle(BaseHTTPRequestHandler):
        def do_POST(self):
            content_len = int(self.headers.getheader('content-length',0))
            post_body = self.rfile.read(content_len)
            print "receive cmq topic publisher request:"
            print self.headers
            print post_body
            post_data = json.loads(post_body)
            for k,v in post_data.iteritems():
                    print "key:%s value:%s" % (k,v)
            #response http status 200     
            self.send_response(200)
            self.end_headers()
            self.wfile.write('ok')
    def start_server(port):
            http_server = HTTPServer(('0.0.0.0', int(port)),TestHTTPHandle)
            http_server.serve_forever()
    if __name__ == '__main__':
            start_server(80)

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