[WIZwiki_W7500ECO] HTTPClient with JSON parser

ORIGINAL POST

By Soohwan Kim

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Hardware Components

WIZwiki-W7500ECO

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Software Apps and online services

mbed

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Description

This post shows how to use HTTPClient parse Json data in ARMmbed platform.

[WIZwiki_W7500ECO] HTTPClient with JSON parser

Components Required

Wizwiki W7500 ECO

Story

JSON is easy for machines to parse and generate which is based on a subset of the JavaScript Programming Language. Currently many Web Services allow to access data in JSON format. However, JSON parser is too big for low-end device as like a ARMmbed platform which has limited-resource. This post shows how to use HTTPClient parse Json data in ARMmbed platform.

Preparation materials

Software
- JSON Parser: MbedJSONValue libs
- Ethernet Networking : WIZnetInterface
- HTTP Server with JSON : Fraka6 Blog – No Free Lunch: The simplest python server example 😉
Hardware
- WIZwiki-W7500ECONET: WIZwiki-W7500 + ECO Shield Ethernet
  - ARMmbed Board: WIZwiki-W7500ECO
  - Ethernet Shield: ECO Shield Ethernet

Simplest python JSON server on PC

Modify Server IP address & port on ron_handler

def run(port=8000): #set port

  print('http server is starting...')
  #ip and port of server
  #server_address = ('127.0.0.1', port)
  server_address = ('192.168.0.223', port)#set port
  httpd = HTTPServer(server_address, Handler)
  print('http server is running...listening on port %s' %port)
  httpd.serve_forever()

Modify JSON form in do_GET handler

#handle GET command
def do_GET(self):
  if format == 'html':
      self.send_response(200)
      self.send_header("Content-type", "text/plain")
      self.send_header('Content-type','text-html')
      self.end_headers()
      self.wfile.write("body")
  elif format == 'json':
      #self.request.sendall(json.dumps({'path':self.path}))
      #self.request.sendall(json.dumps({'pi':3.14}))
      self.request.sendall(json.dumps({'name':'John snow', 'age': 30, 'gender':'male'}))
  else:
      self.request.sendall("%st%s" %('path', self.path))
  return

Execute json_server

Excute json_server
Test by using curl
```
 $>curl ip_address:port_number 
```

Make main.cc

Source Code@https://developer.mbed.org/users/embeddist/code/Simple_HTTPClient_JSON/wiki/Homepage

Network Configration for WIZwiki-W7500ECO

// Enter a MAC address for your controller below.
 uint8_t mac_addr[6] = {0x00, 0x08, 0xDC, 0x00, 0x01, 0x02};

 printf("initializing Ethernetrn");
 // initializing MAC address
 eth.init(mac_addr, "192.168.0.34", "255.255.255.0", "192.168.0.1");

 // Check Ethenret Link
 if(eth.link() == true)   printf("- Ethernet PHY Link-Done rn");
 else printf("- Ethernet PHY Link- Failrn");

 // Start Ethernet connecting: Trying to get an IP address using DHCP
 if (eth.connect()<0)    printf("Fail - Ethernet Connecing");

TCP connect to simple python JSON server

 sock.connect("192.168.0.223", 8000); // "destination IP address", destination port number

Make Get form in HTTP format

 snprintf(http_tx_msg, http_tx_msg_sz,  "GET / HTTP/1.1rnHost: 192.168.0.223:8000rnUser-Agent: WIZwiki-W7500ECOrnConection: closernrn");

TCP Send Get form

 sock.send_all(http_tx_msg, http_tx_msg_sz-1); // tx_buf, tx_buf_size

TCP Recv data in JSON format

 while ( (returnCode = sock.receive(http_rx_msg, http_rx_msg_sz-1)) > 0) {
         http_rx_msg[returnCode] = '';
         printf("Received %d chars from server:nr%sn", returnCode, http_rx_msg);
     }

Do JSON parse
```
 parse(parser, http_rx_msg); 
```

Output the parsed data

 // parsing "string" in string type
 printf("name =%srn" , parser["name"].get<string>().c_str());
 // parsing "age" in integer type
 printf("age =%drn" , parser["age"].get<int>());
 // parsing "gender" in string type
 printf("gender =%srn" , parser["gender"].get<string>().c_str());

Demo. HTTPClient with JSON parser

1. Network config.
2. Confirm Received JSON data
3. Print-out the pasing data

Packet Capture

1. TCP-Connection
2. Target board sends GET Form to simple python JSON server
3. simple python JSON server sends JSON data to Target board

Description

This post shows how to use HTTPClient parse Json data in ARMmbed platform.

[WIZwiki_W7500ECO] HTTPClient with JSON parser

Components Required

Wizwiki W7500 ECO

Story

Preparation materials

Software
- JSON Parser: MbedJSONValue libs
- Ethernet Networking : WIZnetInterface
- HTTP Server with JSON : Fraka6 Blog – No Free Lunch: The simplest python server example 😉
Hardware
- WIZwiki-W7500ECONET: WIZwiki-W7500 + ECO Shield Ethernet
  - ARMmbed Board: WIZwiki-W7500ECO
  - Ethernet Shield: ECO Shield Ethernet

Simplest python JSON server on PC

Modify Server IP address & port on ron_handler

def run(port=8000): #set port

  print('http server is starting...')
  #ip and port of server
  #server_address = ('127.0.0.1', port)
  server_address = ('192.168.0.223', port)#set port
  httpd = HTTPServer(server_address, Handler)
  print('http server is running...listening on port %s' %port)
  httpd.serve_forever()

Modify JSON form in do_GET handler

#handle GET command
def do_GET(self):
  if format == 'html':
      self.send_response(200)
      self.send_header("Content-type", "text/plain")
      self.send_header('Content-type','text-html')
      self.end_headers()
      self.wfile.write("body")
  elif format == 'json':
      #self.request.sendall(json.dumps({'path':self.path}))
      #self.request.sendall(json.dumps({'pi':3.14}))
      self.request.sendall(json.dumps({'name':'John snow', 'age': 30, 'gender':'male'}))
  else:
      self.request.sendall("%st%s" %('path', self.path))
  return

Execute json_server

Excute json_server
Test by using curl
```
 $>curl ip_address:port_number 
```

Make main.cc

Source Code@https://developer.mbed.org/users/embeddist/code/Simple_HTTPClient_JSON/wiki/Homepage

Network Configration for WIZwiki-W7500ECO

// Enter a MAC address for your controller below.
 uint8_t mac_addr[6] = {0x00, 0x08, 0xDC, 0x00, 0x01, 0x02};

 printf("initializing Ethernetrn");
 // initializing MAC address
 eth.init(mac_addr, "192.168.0.34", "255.255.255.0", "192.168.0.1");

 // Check Ethenret Link
 if(eth.link() == true)   printf("- Ethernet PHY Link-Done rn");
 else printf("- Ethernet PHY Link- Failrn");

 // Start Ethernet connecting: Trying to get an IP address using DHCP
 if (eth.connect()<0)    printf("Fail - Ethernet Connecing");

TCP connect to simple python JSON server

 sock.connect("192.168.0.223", 8000); // "destination IP address", destination port number

Make Get form in HTTP format

 snprintf(http_tx_msg, http_tx_msg_sz,  "GET / HTTP/1.1rnHost: 192.168.0.223:8000rnUser-Agent: WIZwiki-W7500ECOrnConection: closernrn");

TCP Send Get form

 sock.send_all(http_tx_msg, http_tx_msg_sz-1); // tx_buf, tx_buf_size

TCP Recv data in JSON format

 while ( (returnCode = sock.receive(http_rx_msg, http_rx_msg_sz-1)) > 0) {
         http_rx_msg[returnCode] = '';
         printf("Received %d chars from server:nr%sn", returnCode, http_rx_msg);
     }

Do JSON parse
```
 parse(parser, http_rx_msg); 
```

Output the parsed data

 // parsing "string" in string type
 printf("name =%srn" , parser["name"].get<string>().c_str());
 // parsing "age" in integer type
 printf("age =%drn" , parser["age"].get<int>());
 // parsing "gender" in string type
 printf("gender =%srn" , parser["gender"].get<string>().c_str());

Demo. HTTPClient with JSON parser

1. Network config.
2. Confirm Received JSON data
3. Print-out the pasing data

Packet Capture

1. TCP-Connection
2. Target board sends GET Form to simple python JSON server
3. simple python JSON server sends JSON data to Target board

documents

Code

Simple HTTP Client with JSON parser

Schematics

WIZwiki-W7500ECO

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