Function log

Table of Contents

• Introduction
• C++ API
• JavaScript API
  • log(message: string): void
  • log(section: string, message: string): void
  • log(section: string, traceId: string, message: string): void
  • log.err(...)
  • log.warn(...)
  • log.info(...)
  • log.debug(...)
• Using custom logging providers
• Developing custom logging providers

<a name="intro"></a> Introduction

Logging is a basic requirement for building services. napajs logging API enables developers to integrate their own logging capabilities in both JavaScript and C++ (addon) world.

A log row may contain the following information:

• (Optional) Section: Useful field to filter log rows. Treatment is defined by logging providers.
• (Optional) Trace ID: Useful field to join logs in the same transaction or request.
• (Required) Message: Log message.
• (Required) Logging level:
  • Error: for application error.
  • Warn: for warning information.
  • Info: for notification.
  • Debug: for debugging purpose.

<a name="cpp-api"></a> C++ API

Include header: <napa.h>

Macros:

• LOG_ERROR(section, format, ...)
• LOG_ERROR_WITH_TRACEID(section, traceId, format, ...)
• LOG_WARNING(section, format, ...)
• LOG_WARNING_WITH_TRACEID(section, traceId, format, ...)
• LOG_INFO(section, format, ...)
• LOG_INFO_WITH_TRACEID(section, traceId, format, ...)
• LOG_DEBUG(section, format, ...)
• LOG_DEBUG_WITH_TRACEID(section, traceId, format, ...)

#include <napa.h>

void MyFunction() {
    // ...
    LOG_ERROR("init", "error: %s", errorMessage.c_str());
}

<a name="js-api"></a> JavaScript API

<a name="log"></a> log(message: string): void

It logs a message. Using info level.

• A log is a shortcut for log.info.*

Example:

var napa = require('napajs');
napa.log('program started');

<a name="log-with-section"></a> log(section: string, message: string): void

It logs a message with a section. Using info level.

Example:

napa.log('init', 'program started');

<a name="log-with-traceid"></a> log(section: string, traceId: string, message: string): void

It logs a message with a section, associating it with a traceId. Using info level.

Example:

napa.log('request', 'A1B2C3D4', 'request received');

<a name="log-err"></a> log.err(...)

It logs an error message. Three variations of arguments are the same with the log.

<a name="log-warn"></a> log.warn(...)

It logs a warning message. Three variations of arguments are the same with the log.

<a name="log-info"></a>log.info(...)

It logs an info message. Three variations of arguments are the same with the log.

<a name="log-debug"></a> log.debug(...)

It logs a debug message. Three combinations of arguments are the same with the log.

<a name="use-custom-providers"></a> Using custom logging providers

Developers can hook up custom logging provider by calling the following before creation of any zones:

napa.runtime.setPlatformSettings({
    "loggingProvider": "<custom-logging-provider-module-name>"
}

<a name="develop-custom-providers"></a> Developing custom logging providers

TBD