td_json_client.h File Reference

Description

C interface for interaction with TDLib via JSON-serialized objects. Can be used to easily integrate TDLib with any programming language which supports calling C functions and is able to work with JSON.

The JSON serialization of TDLib API objects is straightforward: all API objects are represented as JSON objects with the same keys as the API object field names. The object type name is stored in the special field "@type" which is optional in places where type is uniquely determined by the context. Fields of Bool type are stored as Boolean, fields of int32, int53, and double types are stored as Number, fields of int64 and string types are stored as String, fields of bytes type are base64 encoded and then stored as String, fields of array type are stored as Array.

The main TDLib interface is asynchronous. To match requests with a corresponding response, the field "@extra" can be added to the request object. The corresponding response will have an "@extra" field with exactly the same value. Each returned object will have an "@client_id" field, containing the identifier of the client for which a response or an update was received.

A TDLib client instance can be created through td_create_client_id. Requests can be sent using td_send and the received client identifier. New updates and responses to requests can be received through td_receive from any thread after the first request has been sent to the client instance. This function must not be called simultaneously from two different threads. Also, note that all updates and responses to requests must be applied in the order they were received for consistency. Some TDLib requests can be executed synchronously from any thread using td_execute. TDLib client instances are destroyed automatically after they are closed. All TDLib client instances must be closed before application termination to ensure data consistency.

General pattern of usage:

int client_id = td_create_client_id();
// share the client_id with other threads, which will be able to send requests via td_send

const double WAIT_TIMEOUT = 10.0; // seconds
while (true) {
  const char *result = td_receive(WAIT_TIMEOUT);
  if (result) {
    // parse the result as a JSON object and process it as an incoming update or the answer to a previously sent request
  }
}

Alternatively, you can use old TDLib JSON interface, which will be removed in TDLib 2.0.0.

Objects and functions serialization to JSON is the same for both JSON interfaces.

The main TDLib interface is asynchronous. To match requests with a corresponding response a field "@extra" can be added to the request object. The corresponding response will have an "@extra" field with exactly the same value.

A TDLib client instance can be created through td_json_client_create. Requests then can be sent using td_json_client_send from any thread. New updates and request responses can be received through td_json_client_receive from any thread. This function must not be called simultaneously from two different threads. Also, note that all updates and request responses must be applied in the order they were received to ensure consistency. Given this information, it's advisable to call this function from a dedicated thread. Some service TDLib requests can be executed synchronously from any thread by using td_json_client_execute. The TDLib client instance can be destroyed via td_json_client_destroy.

General pattern of usage:

void *client = td_json_client_create();
// somehow share the client with other threads, which will be able to send requests via td_json_client_send

const double WAIT_TIMEOUT = 10.0; // seconds
int is_closed = 0;  // should be set to 1, when updateAuthorizationState with authorizationStateClosed is received
while (!is_closed) {
  const char *result = td_json_client_receive(client, WAIT_TIMEOUT);
  if (result) {
    // parse the result as JSON object and process it as an incoming update or an answer to a previously sent request
  }
}
td_json_client_destroy(client);

Go to the source code of this file.

Typedefs
typedef void(*	td_log_message_callback_ptr) (int verbosity_level, const char *message)

Functions
int	td_create_client_id ()
void	td_send (int client_id, const char *request)
const char *	td_receive (double timeout)
const char *	td_execute (const char *request)
void	td_set_log_message_callback (int max_verbosity_level, td_log_message_callback_ptr callback)
void *	td_json_client_create ()
void	td_json_client_send (void *client, const char *request)
const char *	td_json_client_receive (void *client, double timeout)
const char *	td_json_client_execute (void *client, const char *request)
void	td_json_client_destroy (void *client)

Typedef Documentation

td_log_message_callback_ptr

typedef void(* td_log_message_callback_ptr) (int verbosity_level, const char *message)

A type of callback function that will be called when a message is added to the internal TDLib log.

Parameters

verbosity_level	Log verbosity level with which the message was added from -1 up to 1024. If 0, then TDLib will crash as soon as the callback returns. None of the TDLib methods can be called from the callback.
message	Null-terminated UTF-8-encoded string with the message added to the log.

Function Documentation

td_create_client_id()

int td_create_client_id

(

)

Returns an opaque identifier of a new TDLib instance. The TDLib instance will not send updates until the first request is sent to it.

Returns

Opaque identifier of a new TDLib instance.

td_send()

void td_send	(	int	client_id,
		const char *	request
	)

Sends request to the TDLib client. May be called from any thread.

Parameters

[in]	client_id	TDLib client identifier.
[in]	request	JSON-serialized null-terminated request to TDLib.

td_receive()

const char* td_receive

(

double

timeout

)

Receives incoming updates and request responses. Must not be called simultaneously from two different threads. The returned pointer can be used until the next call to td_receive or td_execute, after which it will be deallocated by TDLib.

Parameters

[in]

timeout

The maximum number of seconds allowed for this function to wait for new data.

Returns

JSON-serialized null-terminated incoming update or request response. May be NULL if the timeout expires.

td_execute()

const char* td_execute

(

const char *

request

)

Synchronously executes a TDLib request. A request can be executed synchronously, only if it is documented with "Can be called synchronously". The returned pointer can be used until the next call to td_receive or td_execute, after which it will be deallocated by TDLib.

Parameters

[in]

request

JSON-serialized null-terminated request to TDLib.

Returns

JSON-serialized null-terminated request response.

td_set_log_message_callback()

void td_set_log_message_callback	(	int	max_verbosity_level,
		td_log_message_callback_ptr	callback
	)

Sets the callback that will be called when a message is added to the internal TDLib log. None of the TDLib methods can be called from the callback. By default the callback is not set.

Parameters

[in]	max_verbosity_level	The maximum verbosity level of messages for which the callback will be called.
[in]	callback	Callback that will be called when a message is added to the internal TDLib log. Pass nullptr to remove the callback.

td_json_client_create()

void* td_json_client_create

(

)

Creates a new instance of TDLib.

Returns

Pointer to the created instance of TDLib.

td_json_client_send()

void td_json_client_send	(	void *	client,
		const char *	request
	)

Sends request to the TDLib client. May be called from any thread.

Parameters

[in]	client	The client.
[in]	request	JSON-serialized null-terminated request to TDLib.

td_json_client_receive()

const char* td_json_client_receive	(	void *	client,
		double	timeout
	)

Receives incoming updates and request responses from the TDLib client. May be called from any thread, but must not be called simultaneously from two different threads. Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute in the same thread, so it can't be used after that.

Parameters

[in]	client	The client.
[in]	timeout	The maximum number of seconds allowed for this function to wait for new data.

Returns

JSON-serialized null-terminated incoming update or request response. May be NULL if the timeout expires.

td_json_client_execute()

const char* td_json_client_execute	(	void *	client,
		const char *	request
	)

Synchronously executes TDLib request. May be called from any thread. Only a few requests can be executed synchronously. Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute in the same thread, so it can't be used after that.

Parameters

[in]	client	The client. Currently, ignored for all requests, so NULL can be passed.
[in]	request	JSON-serialized null-terminated request to TDLib.

Returns

JSON-serialized null-terminated request response.

td_json_client_destroy()

void td_json_client_destroy

(

void *

client

)

Destroys the TDLib client instance. After this is called the client instance must not be used anymore.

Parameters

[in]

client

The client.