https://www.opensips.org/Documentation/Development-Manual
15. BIN Interface API
Binary Internal Interface是一種OpenSIPS 核心接口，它在單個OpenSIPS 實例之間提供一種高效的通信方式。
這在無法將實時數據（比如說dialog數據）簡單寫入數據庫時就非常有利，因爲故障遷移需要幾分鐘才能完成。可以通過BIN接口，把所有事件相關的運行數據備份到備用OpenSIPS 實例。BIN接口功能聲明在 bin_interface.h文件中.
接口使用需要兩個步驟：
- 在主服務器上創建併發送新事件
- 在備用服務器上接收並處理事件
以下方法用於創建和發送新事件：
/**
* bin_init - begins the construction of a new binary packet (header part):
*
* +-------------------+------------------------------------------------------+
* | 8-byte HEADER | BODY max 65535 bytes |
* +-------------------+------------------------------------------------------+
* | PK_MARKER | CRC | LEN | MOD_NAME | CMD | LEN | FIELD | LEN | FIELD |...|
* +-------------------+------------------------------------------------------+
*
* @param: { LEN, MOD_NAME } + CMD
*/
int bin_init(str *mod_name, int cmd_type)
/*
* copies the given string at the 'cpos' position in the buffer
* allows null strings (NULL content or NULL param)
*
* @return: 0 on success
*/
int bin_push_str(const str *info)
/*
* adds a new integer value at the 'cpos' position in the buffer
*
* @return: 0 on success
*/
int bin_push_int(int info)
/**
* bin_send - computes the checksum of the current packet and then
* sends the packet over UDP to the @dest destination
*
* @return: number of bytes sent, or -1 on error
*/
int bin_send(union sockaddr_union *dest)
在接收側，開發者首先註冊回調函數，它將在接收特定類型的BIN消息時觸發：
/**
* bin_register_cb - registers a module handler for specific packets
* @mod_name: used to classify the incoming packets
* @cb: the handler function, called once for each matched packet
*
* @return: 0 on success
*/
int bin_register_cb(char *mod_name, void (*cb)(int))
只有mod_name類別的BIN消息會觸發註冊的回調函數，回調函數也會收到消息包，以便區分不同的事件（比如說eg. create, update, delete, etc ）。然後，你需要使用pop方法提取消息包的內容：
/*
* pops an str from the current position in the buffer
* @info: pointer to store the result
*
* @return: 0 on success
*
* Note: The pointer returned in @info str is only valid for the duration of
* the callback. Don't forget to copy the info into a safe buffer!
*/
int bin_pop_str(str *info)
/*
* pops an integer value from the current position in the buffer
* @info: pointer to store the result
*
* @return: 0 on success
*/
int bin_pop_int(void *info)
https://www.opensips.org/Documentation/Interface-Binary-2-2這個頁面專注於解釋如何配置OpenSIPS 的BNI。