HTTP Client interface that contains the method that a class that can be used to send and receive data over an HTTP conection should implement. More...

#include <IHTTP_Client.h>

Public Member Functions
virtual	~IHTTP_Client ()
	Virtual default destructor, created to ensure that if a pointer to this class is used and deleted, we will also call the derived base class destructor. More...

virtual void	set_keep_alive (bool keep_alive)=0
	Sets whether to close the HTTP connection for every single request and reconnect once a new request is sent. More...

virtual int	connect (char const *host, uint16_t port)=0
	Connects to the given server instance over the defined port. More...

virtual void	stop ()=0
	Disconnects the given device from the current host and clears about any remaining bytes still in the reponse body. More...

virtual int	post (char const url_path, char const content_type, char const *request_body)=0
	Connects to the server and sends a POST request with a body and content type. More...

virtual int	get_response_status_code ()=0
	Gets the HTTP status code contained in the server response. More...

virtual int	get (const char *url_path)=0
	Connects to the server and sends a GET request. More...

virtual std::string	get_response_body ()=0
	Returns the response body of a previously sent message as a string object, skips any response headers if they have not been read already, should be called after calling get_response_status_code() and ensuring the request was successful. More...

Detailed Description

HTTP Client interface that contains the method that a class that can be used to send and receive data over an HTTP conection should implement.

Note: Seperates the specific implementation used from the ThingsBoardHttp client, allows to use different clients depending on different needs. In this case the main use case of the seperation is to both support Espressif IDF and Arduino with the following libraries as recommendations. The default HTTP Client for Arduino is the ArduinoHttpClient (https://github.com/arduino-libraries/ArduinoHttpClient), For Espressif IDF however the default HTTP Client is the esp-http-client (https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/protocols/esp_http_client.html) component. The aforementioned recommendations are already partially implemented in the library and can can simply be used and included when using the library, for Arduino the Arduino_HTTP_Client can simply be included and for Espressif IDF the implementations has not been created yet, the implementations have been tested and should be compatible when used in conjunction with the ThingsBoardHttp client

Constructor & Destructor Documentation

◆ ~IHTTP_Client()

virtual IHTTP_Client::~IHTTP_Client ( )

inlinevirtual

Virtual default destructor, created to ensure that if a pointer to this class is used and deleted, we will also call the derived base class destructor.

Note: Deleting a base class destructor that does not have a virtual destructor is undefined behaviour, because the derived class destructor originally instantiated with new is never called. This can cause potential memory leaks, because derived classes can not clean up their internal members as expected and instead simply leak them

Member Function Documentation

◆ connect()

virtual int IHTTP_Client::connect	(	char const *	host,
		uint16_t	port
	)

pure virtual

Connects to the given server instance over the defined port.

Parameters

host Non owning pointer to server instance name the client should connect too. Does not need to be kept alive, because the server name is only used for the scope of the method itself

port Port that will be used to establish a connection and send / receive data Should be either 80 for unencrypted HTTP or 443 for HTTPS with encryption. The latter is recommended if relevant data is sent or if the client receives and handles requests from the server, because using an unencrpyted connection, will allow 3rd parties to listen to the communication and impersonate the server sending payloads which might influence the device in unexpected ways

Returns: Whether the client could establish the connection successfully with return code 0 or failed with error code otherwise

◆ get()

virtual int IHTTP_Client::get ( const char * url_path )

pure virtual

Connects to the server and sends a GET request.

Parameters

url_path Non owning pointer to URL path the GET request should be sent too. Does not need to be kept alive, because the url path is only used for the scope of the method itself

Returns: Whether the request was successful or not, returns 0 if successful or if not the internal error code

◆ get_response_body()

virtual std::string IHTTP_Client::get_response_body ( )

pure virtual

Returns the response body of a previously sent message as a string object, skips any response headers if they have not been read already, should be called after calling get_response_status_code() and ensuring the request was successful.

Returns: Response body of a request

◆ get_response_status_code()

virtual int IHTTP_Client::get_response_status_code ( )

pure virtual

Gets the HTTP status code contained in the server response.

Note: Should follow the HTTP standard, meaning 200 for a successful request or 404 for file not found, see https://developer.mozilla.org/en-US/docs/Web/HTTP/Status for more information on all standard status codes

Returns: Current HTTP status code from the server response

◆ post()

virtual int IHTTP_Client::post	(	char const *	url_path,
		char const *	content_type,
		char const *	request_body
	)

pure virtual

Connects to the server and sends a POST request with a body and content type.

Parameters

url_path	Non owning pointer to URL path the POST request should be sent too. Does not need to be kept alive, because the url path is only used for the scope of the method itself
content_type	Non owning pointer to type of the content that is sent will be JSON data most of the time. Does not need to be kept alive, because the content type is only used for the scope of the method itself
request_body	Non owning pointer to request body containing data of the given content type. Does not need to be kept alive, because the request body is only used for the scope of the method itself

Returns: Whether the request was successful or not, returns 0 if successful or if not the internal error code

◆ set_keep_alive()

virtual void IHTTP_Client::set_keep_alive ( bool keep_alive )

pure virtual

Sets whether to close the HTTP connection for every single request and reconnect once a new request is sent.

Parameters

keep_alive Enable or disable to keep the connection alive after a message has been sent Is recommended to be always enabled to improve performance and speed, because opening a new connection takes a while especially when using HTTPS

◆ stop()

virtual void IHTTP_Client::stop ( )

pure virtual

Disconnects the given device from the current host and clears about any remaining bytes still in the reponse body.

The documentation for this class was generated from the following file:

src/IHTTP_Client.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ ~IHTTP_Client()

Member Function Documentation

◆ connect()

◆ get()

◆ get_response_body()

◆ get_response_status_code()

◆ post()

◆ set_keep_alive()

◆ stop()