Logging Plugin API
==================

Servers and clients must define a logger in their configuration. The logger
is just a function pointer. Every log-message consists of a log-level, a
log-category and a string message content. The timestamp of the log-message
is created within the logger.

.. code-block:: c

   
   typedef enum {
       UA_LOGLEVEL_TRACE,
       UA_LOGLEVEL_DEBUG,
       UA_LOGLEVEL_INFO,
       UA_LOGLEVEL_WARNING,
       UA_LOGLEVEL_ERROR,
       UA_LOGLEVEL_FATAL
   } UA_LogLevel;
   
   typedef enum {
       UA_LOGCATEGORY_NETWORK,
       UA_LOGCATEGORY_SECURECHANNEL,
       UA_LOGCATEGORY_SESSION,
       UA_LOGCATEGORY_SERVER,
       UA_LOGCATEGORY_CLIENT,
       UA_LOGCATEGORY_USERLAND,
       UA_LOGCATEGORY_SECURITYPOLICY
   } UA_LogCategory;
   
The message string and following varargs are formatted according to the rules
of the printf command. Do not call the logger directly. Instead, make use of
the convenience macros that take the minimum log-level defined in ua_config.h
into account.

.. code-block:: c

   
   typedef void (*UA_Logger)(UA_LogLevel level, UA_LogCategory category,
                             const char *msg, va_list args);
   
   static UA_INLINE UA_FORMAT(3,4) void
   UA_LOG_TRACE(UA_Logger logger, UA_LogCategory category, const char *msg, ...) {
   #if UA_LOGLEVEL <= 100
       va_list args; va_start(args, msg);
       logger(UA_LOGLEVEL_TRACE, category, msg, args);
       va_end(args);
   #endif
   }
   
   static UA_INLINE UA_FORMAT(3,4) void
   UA_LOG_DEBUG(UA_Logger logger, UA_LogCategory category, const char *msg, ...) {
   #if UA_LOGLEVEL <= 200
       va_list args; va_start(args, msg);
       logger(UA_LOGLEVEL_DEBUG, category, msg, args);
       va_end(args);
   #endif
   }
   
   static UA_INLINE UA_FORMAT(3,4) void
   UA_LOG_INFO(UA_Logger logger, UA_LogCategory category, const char *msg, ...) {
   #if UA_LOGLEVEL <= 300
       va_list args; va_start(args, msg);
       logger(UA_LOGLEVEL_INFO, category, msg, args);
       va_end(args);
   #endif
   }
   
   static UA_INLINE UA_FORMAT(3,4) void
   UA_LOG_WARNING(UA_Logger logger, UA_LogCategory category, const char *msg, ...) {
   #if UA_LOGLEVEL <= 400
       va_list args; va_start(args, msg);
       logger(UA_LOGLEVEL_WARNING, category, msg, args);
       va_end(args);
   #endif
   }
   
   static UA_INLINE UA_FORMAT(3,4) void
   UA_LOG_ERROR(UA_Logger logger, UA_LogCategory category, const char *msg, ...) {
   #if UA_LOGLEVEL <= 500
       va_list args; va_start(args, msg);
       logger(UA_LOGLEVEL_ERROR, category, msg, args);
       va_end(args);
   #endif
   }
   
   static UA_INLINE UA_FORMAT(3,4) void
   UA_LOG_FATAL(UA_Logger logger, UA_LogCategory category, const char *msg, ...) {
   #if UA_LOGLEVEL <= 600
       va_list args; va_start(args, msg);
       logger(UA_LOGLEVEL_FATAL, category, msg, args);
       va_end(args);
   #endif
   }
   
Convenience macros for complex types
------------------------------------

.. code-block:: c

   #define UA_PRINTF_GUID_FORMAT "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x"
   #define UA_PRINTF_GUID_DATA(GUID) (GUID).data1, (GUID).data2, (GUID).data3, \
           (GUID).data4[0], (GUID).data4[1], (GUID).data4[2], (GUID).data4[3], \
           (GUID).data4[4], (GUID).data4[5], (GUID).data4[6], (GUID).data4[7]
   
   #define UA_PRINTF_STRING_FORMAT "\"%.*s\""
   #define UA_PRINTF_STRING_DATA(STRING) (int)(STRING).length, (STRING).data