https://www.opensips.org/Documentation/Development-Manual
15. BIN Interface API
Binary Internal Interface是一种OpenSIPS 核心接口，它在单个OpenSIPS 实例之间提供一种高效的通信方式。
这在无法将实时数据（比如说dialog数据）简单写入数据库时就非常有利，因为故障迁移需要几分钟才能完成。可以通过BIN接口，把所有事件相关的运行数据备份到备用OpenSIPS 实例。BIN接口功能声明在 bin_interface.h文件中.
接口使用需要两个步骤：
- 在主服务器上创建并发送新事件
- 在备用服务器上接收并处理事件
以下方法用于创建和发送新事件：
/**
* 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)
在接收侧，开发者首先注册回调函数，它将在接收特定类型的BIN消息时触发：
/**
* 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类别的BIN消息会触发注册的回调函数，回调函数也会收到消息包，以便区分不同的事件（比如说eg. create, update, delete, etc ）。然后，你需要使用pop方法提取消息包的内容：
/*
* 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这个页面专注于解释如何配置OpenSIPS 的BNI。