# Ingest MQTT Data into HTTP Server

HTTP Server is the channel through which EMQX sends messages to HTTP services. Through HTTP servers, users can send messages to the remote HTTP service from a local topic, or from the output of a rule.

Prerequisites

Knowledge about EMQX data integration rules
Knowledge about data bridge

# Feature List

# Quick Start Tutorial

This section introduces how to configure an HTTP Server data bridge, including how to set up an HTTP server, configure an HTTP server data bridge to connect to the HTTP server, and test the data bridge and rule.

# Set up a Simple HTTP Server

Use Python to build a simple HTTP service. This HTTP service will receive the POST / requests and will return 200 OK after printing the requested content:

from flask import Flask, json, request

api = Flask(__name__)

@api.route('/', methods=['POST'])
def print_messages():
  reply= {"result": "ok", "message": "success"}
  print("got post request: ", request.get_data())
  return json.dumps(reply), 200

if __name__ == '__main__':
  api.run()

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Save the above code as http_server.py file. Then start the server by running:

pip install flask

python3 http_server.py

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# Create an HTTP Server Data Bridge

Go to EMQX Dashboard, and click Integration -> Data Bridge.
Click Create on the top right corner of the page. Click to select the HTTP Server and click Next:
Input a name for the data bridge. The name should be a combination of upper/lower case letters or numbers, for example, my_httpserver.
Set URL to http://localhost:5000. For the rest, you can keep the default value.
Before clicking Create, you can click Test Connectivity to test that the bridge can connect to the HTTP server.
Click Create to finish the creation of the data bridge.
A confirmation dialog will appear and ask if you like to create a rule using this data bridge, you can click Create Rule to continue creating rules to specify the data to be saved into HTTP Server. You can also create rules by following the steps in Create a Rule for HTTP Server Data Bridge.

Now the HTTP server data bridge should appear in the data bridge list (Integration -> Data Bridge) with Resource Status as Connected.

# Create a Rule for HTTP Server Data Bridge

Now you have successfully created the data bridges to HTTP Server. you can continue to create a rule to forward data to the HTTP Server.

Go to EMQX Dashboard, and click Integration -> Rules.
Click Create on the top right corner of the page.
Input my_rule as the rule ID, and set the rules in the SQL Editor.
Input the following statement in the SQL Editor as an example, which means the MQTT messages under topic t/# will be saved to the HTTP server.
Note: If you want to specify your own SQL syntax, make sure that you have included all fields required by the data bridge in the SELECT part.
```
SELECT
  *
FROM
  "t/#"
```
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Click the Add Action button, select Forwarding with Data Bridge from the dropdown list and then select the data bridge you just created under Data bridge. Then click the Add button.
Click the Create button at the page bottom to finish the creation.

Now a rule to forward data to the HTTP server via an HTTP Server data bridge is created. You can click Integration -> Flows to view the topology. It can be seen that the messages under topic t/# are sent and saved to the HTTP server.

# Test the Data Bridge and Rule

Use MQTTX to send a message to topic t/1 to trigger an online/offline event.

mqttx pub -i emqx_c -t t/1 -m '{ "msg": "hello HTTP Server" }'

Check the running status of the two data bridges, there should be one new incoming and one new outgoing message.

Verify whether the message has been sent to the HTTP server:

python3 http_server.py
 * Serving Flask app 'http_server' (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://127.0.0.1:5000 (Press CTRL+C to quit)

got post request:  b'hello HTTP Server'

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