HttpClient Class

HttpClient Class

Description
Defines a class of using HttpClient

Syntax
class HttpClient

Members

Public Constructors 
HttpClient::HttpClientConstructs a HttpClient object
Public Methods 
HttpClient::beginRequestStart a more complex request
HttpClient::endRequestEnd a more complex request
HttpClient::getConnect to the server and start to send a GET request
HttpClient::postConnect to the server and start to send a POST request
HttpClient::putConnect to the server and start to send a PUT request
HttpClient::startRequestConnect to the server and start to send the request
HttpClient::sendHeaderSend an additional header line
HttpClient::sendBasicAuthSend a basic authentication header
HttpClient::finishRequestFinish sending the HTTP request
HttpClient::responseStatusCodeGet the HTTP status code contained in the response
HttpClient::readHeaderRead the next character of the response headers
HttpClient::skipResponseHeadersSkip any response headers to get to the body
HttpClient::endOfHeadersReachedTest whether all of the response headers have been consumed
HttpClient::endOfBodyReachedTest whether the end of the body has been reached
HttpClient::contentLengthReturn the length of the body

HttpClient::HttpClient

Description
Constructs a HttpClient object. If Marco “PROXY_ENABLED” is defined, currently disabled as introduces a dependency on DNS.h in Ethernet.

Syntax
HttpClient::HttpClient(Client& aClient, const char* aProxy = NULL, uint16_t aProxyPort = 0);
HttpClient::HttpClient(Client& aClient);

Parameters
aClient: The object of class WiFiClient.
aProxy: The proxy name. The default proxy name is “NULL”.
aProxyPort: The proxy port. The default value for the proxy port is 0.

Returns
The function returns nothing.

Example Code
Example: SimpleHttpExample
The example demonstrate how to download the content from URL indicated in kHostname[].

#include <HttpClient.h>   
#include <WiFi.h>   
#include <WiFiClient.h>   

char ssid[] = "YourNetwork"; //  your network SSID (name)   
char pass[] = "password";    // your network password (use for WPA, or use as key for WEP)  
int keyIndex = 0;            // your network key Index number (needed only for WEP)

//Name of the server we want to connect to  
const char kHostname[] = "www.google.com";  
const char kPath[] = "/";  
//Number of milliseconds to wait without receiving any data before we give up  
const int kNetworkTimeout = 30*1000;  
//Number of milliseconds to wait if no data is available before trying again  
const int kNetworkDelay = 1000;  
int status = WL_IDLE_STATUS;  

void setup() {  
 
Serial.begin(9600);   
while ( status != WL_CONNECTED) {   
  Serial.print("Attempting to connect to SSID: ");  
  Serial.println(ssid);  
  status = WiFi.begin(ssid, pass);  
  // wait 10 seconds for connection:  
  delay(10000);  
}   
Serial.println("Connected to wifi");  
printWifiStatus();  
 

void loop() { 
 
int err =0;  
WiFiClient c;  
HttpClient http(c);  
err = http.get(kHostname, kPath);  
if (err == 0)  
{  
  Serial.println("startedRequest ok");  

  err = http.responseStatusCode();  
  if (err >= 0)  
  {  
    Serial.print("Got status code: ");  
    Serial.println(err);  

    // Usually you'd check that the response code is 200 or a  
    // similar "success" code (200-299) before carrying on,  
    // but we'll print out whatever response we get  

    err = http.skipResponseHeaders();  
    if (err >= 0)  
    {  
      int bodyLen = http.contentLength();  
      Serial.print("Content length is: ");  
      Serial.println(bodyLen);  
      Serial.println();  
      Serial.println("Body returned follows:");  
      
      // Now we've got to the body, so we can print it out  
      unsigned long timeoutStart = millis();  
      char c;  
      // Whilst we haven't timed out & haven't reached the end of the body  
      while ( (http.connected() || http.available()) &&  
             ((millis() - timeoutStart) < kNetworkTimeout) )  
      {  
          if (http.available())  
          {  
              c = http.read();  
              // Print out this character  
              Serial.print(c);  
               
              bodyLen--;  
              // We read something, reset the timeout counter  
              timeoutStart = millis();  
          }  
          else  
          {  
              // We haven't got any data, so let's pause to allow some to arrive 
              delay(kNetworkDelay);  
          }  
      }  
    }  
    else  
    {  
      Serial.print("Failed to skip response headers: ");  
      Serial.println(err);  
    }  
  }  
  else  
  {      
    Serial.print("Getting response failed: ");  
    Serial.println(err);  
  }  
}  
else  
{  
  Serial.print("Connect failed: ");  
	  Serial.println(err);  
	}  
	http.stop();  
	// And just stop, now that we've tried a download  
	while(1);  
}  
void printWifiStatus() {  
  // print the SSID of the network you're attached to:  
  Serial.print("SSID: ");  
  Serial.println(WiFi.SSID());  
  // print your WiFi shield's IP address:  
  IPAddress ip = WiFi.localIP();  
  Serial.print("IP Address: ");  
  Serial.println(ip);  
  // print the received signal strength:  
  long rssi = WiFi.RSSI();  
  Serial.print("signal strength (RSSI):");  
  Serial.print(rssi);  
  Serial.println(" dBm");  
}  

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::beginRequest

Description
Start a more complex request. Use this when you need to send additional headers in the request, but you will also need to call endRequest() when you are finished.

Syntax
void HttpClient::beginRequest(void);

Parameters
The function requires no input parameter.

Returns
The function returns nothing.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::endRequest

Description
End a more complex request. Use this when you need to have sent additional headers in the request, but you will also need to call beginRequest() at the start.

Syntax
void HttpClient::endRequest(void);

Parameters
The function requires no input parameter.

Returns
The function returns nothing.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::get

Description
Connect to the server and start to send a “GET” request. If the input parameter contains “aServerAddress”, the connection will not perform a DNS lookup and just purely connect to the given IP address.

Syntax
int HttpClient::get(const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::get(const char* aServerName, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::get(const IPAddress& aServerAddress, const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::get(const IPAddress& aServerAddress, const char* aServerName, const char* aURLPath, const char* aUserAgent = NULL);

Parameters
aServerName: The name of the server being connected to. If aServerName is “NULL”, the “Host” header line will not be sent.
aServerPort: The port on which server connected.
aURLPath: The URL to request.
aUserAgent: User-Agent string to be sent. If aUserAgent indicated as “NULL”, the default user-agent kUserAgent will be sent.
aServerAddress: IP address of the server to connect to.

Returns
Return 0 if successful, otherwise indicates an error occurs.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::post

Description
Connect to the server and start to send a “POST” request. If the input parameter has “aServerAddress”, connects doesn’t perform a DNS lookup and just connects to the given IP address.

Syntax
int HttpClient::post(const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::post(const char* aServerName, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::post(const IPAddress& aServerAddress, const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::post(const IPAddress& aServerAddress, const char* aServerName, const char* aURLPath, const char* aUserAgent = NULL);

Parameters
aServerName: Name of the server being connected to. If NULL, the “Host” header line won’t be sent.
aServerPort: Port to connect to on the server.
aURLPath: Url to request.
aUserAgent: User-Agent string to be sent. If aUserAgent indicated as “NULL”, the default user-agent kUserAgent will be sent.
aServerAddress: IP address of the server to connect to.

Returns
Return 0 if successful, otherwise indicates an error occurs.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::put

Description
Connect to the server and start to send a PUT request. If the input parameter has “aServerAddress”, connects doesn’t perform a DNS lookup and just connects to the given IP address.

Syntax
int HttpClient::put(const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::put(const char* aServerName, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::put(const IPAddress& aServerAddress, const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aUserAgent = NULL);
int HttpClient::put(const IPAddress& aServerAddress, const char* aServerName, const char* aURLPath, const char* aUserAgent = NULL);

Parameters
aServerName: Name of the server being connected to. If NULL, the “Host” header line won’t be sent.
aServerPort: Port to connect to on the server.
aURLPath: Url to request.
aUserAgent: User-Agent string to be sent. If aUserAgent indicated as “NULL”, the default user-agent kUserAgent will be sent.
aServerAddress: IP address of the server to connect to.

Returns
Return 0 if successful, otherwise indicates an error occurs.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::startRequest

Description
Connect to the server and start to send the request.

Syntax
int HttpClient::startRequest(const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aHttpMethod, const char* aUserAgent);
int HttpClient::startRequest(const IPAddress& aServerAddress, const char* aServerName, uint16_t aServerPort, const char* aURLPath, const char* aHttpMethod, const char* aUserAgent);

Parameters
aServerAddress: IP address of the server to connect to.
aServerName: Name of the server being connected to. If NULL, the “Host” header line won’t be sent.
aServerPort: Port to connect to on the server.
aURLPath: Url to request.
aHttpMethod: Type of HTTP request to make, e.g. “GET”, “POST”, etc.
aUserAgent: User-Agent string to send. If NULL the default user-agent kUserAgent will be sent.

Returns
Return 0 if successful, else error.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::sendHeader

Description
The function sends an additional header line.
The function void HttpClient:: sendHeader(const char* aHeader);can only be called in between the calls to startRequest and finishRequest.

The other 2 functions void HttpClient::sendHeader(const char* aHeaderName, const char* aHeaderValue); and void HttpClient::sendHeader(const char* aHeaderName, const int aHeaderValue); are alternate form the previous one, which takes the header name and content as separately (as strings or integer). For example, to send an XXXXXX header, user might call sendHeader(“XXXXX”, “Something”) or sendHeader(“XXXXX”, 123).And the call will add the “: ” in the log to separate different header in the case of multiple headers.

Syntax
void HttpClient::sendHeader(const char* aHeader);

void HttpClient::sendHeader(const char* aHeaderName, const char* aHeaderValue);

void HttpClient::sendHeader(const char* aHeaderName, const int aHeaderValue);

Parameters
aHeader: Header line to send, in its entirety (but without the trailing CRLF. E.g. “Authorization: Basic YQDDCAIGES”.
aHeaderName: Type of header being sent.
aHeaderValue: Value for that header.

Returns
The function returns nothing.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::sendBasicAuth

Description
The function sends a basic authentication header which will encode the given username and password, and send them in a suitable header line for doing Basic Authentication.

Syntax
void HttpClient::sendBasicAuth(const char* aUser, const char* aPassword);

Parameters
aUser: Username for the authorization.
aPassword: Password for the user aUser.

Returns
The function returns nothing.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::finishRequest

Description
Finish sending the HTTP request. The function sends a blank line to signify the end of the request.

Syntax
void HttpClient::finishRequest(void);

Parameters
The function requires no input parameter.

Returns
The function returns nothing.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::responseStatusCode

Description
Get the HTTP status code contained in the response. For example, “200” for successful requests, “404” for file not found, etc.

Syntax
int HttpClient::responseStatusCode(void);

Parameters
The function requires no input parameter.

Returns
Return 0 if successful, else error.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::readHeader

Description
The function reads the next character of the response headers. This functions the same as read() but to be used when reading through the headers which are slightly less efficient. The user might check whether the end of the headers has been reached by calling endOfHeadersReached(), although after that point this will still return data as read() would.

Syntax
int HttpClient::readHeader(void);

Parameters
The function requires no input parameter.

Returns
Return the next character of the response headers.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::skipResponseHeaders

Description
Skip any response headers to get to the body. Use this if you don’t want to do any special processing of the headers returned in the response. You can also use it after you’ve found all of the headers you’re interested in, and just want to get on with processing the body.

Syntax
int HttpClient::skipResponseHeaders(void);

Parameters
The function requires no input parameter.

Returns
Return 0 if successful, else error.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::endOfHeadersReached

Description
Test whether all of the response headers have been consumed.

Syntax
bool HttpClient::endOfHeadersReached(void);

Parameters
The function requires no input parameter.

Returns
Return true if we are now processing the response body, else false.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::endOfBodyReached

Description
Test whether the end of the body has been reached. It only works if the Content-Length header was returned by the server.

Syntax
bool HttpClient::endOfBodyReached(void);

Parameters
The function requires no input parameter.

Returns
Return true if we are now at the end of the body, else false.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

HttpClient::contentLength

Description
The function returns the length of the body.

Syntax
int HttpClient::contentLength(void);

Parameters
The function requires no input parameter.

Returns
Return Length of the body, in bytes, or kNoContentLengthHeader if no Content-Length header was returned by the server.

Example Code
Example: SimpleHttpExample
The example demonstrates how to download the content from the URL indicated in kHostname[]. Details of the code can be found in the previous section of HttpClient:: HttpClient.

Notes and Warnings
Include “HttpClient.h” to use the class function.
 

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