pdjr-signalk / signalk-liblog

Log system interface library for Signal K node plugins.

signalk-liblog

Log system interface library for Signal K node plugins.

Provides two small classes.

The Log class supports message logging to the Signal K dashboard and host system logs.

The DebugLog class supports logging to the host system logs dependent upon the presence of debug keys in the environment DEBUG variable.

Using the Log class

const Log = require("signalk-liblog/Log.js");

/**********************************************************************
 * Create new log instance, setting the message prefix to be used for
 * system log messages and 'normal' and 'error' callback functions that
 * will be used to interface to the Signal K dashboard.
 */

const log = new Log(plugin.id, { ncallback: app.setProviderStatus, ecallback: app.setProviderError });

/**********************************************************************
 * Issue a 'normal', 'warning' and 'error' messages to both the system
 * log and through the Signal K dashboard callbacks.
 */

log.N("server listening on UDP port %d", udpPort);
log.W("using default UDP port %d", udpPort);
log.E("error opening UDP port %d", udpPort);

/**********************************************************************
 * Issue an 'error' message to just the system log.
 */

log.E("server rejected invalid client", false);

Constructor

Log(prefix [, options ])

Create a new Log instance. prefix is arbitrary text that will be prepended to messages written to the system log. options is object perhaps containing the following properties.

options.ncallback - callback function to be used for normal messages (i.e. those generated by a call to the N method. Defaults to undefined.

options.wcallback - callback function to be used for warning messages (i.e. those generated by a call to the W method. Defaults to options.ncallback.

options.ecallback - callback function to be used for error messages (i.e. those generated by a call to the E method. Defaults to *options.ncallback.

options.prefixall - boolean value which if true causes prefix to be prepended to all output (and not just system log output). Defaults to false.

Methods

N(message [, nocallback ])

Write a 'normal' message of the form "prefix: message" to the system log and, by default, pass a message of the form "message" to the normal callback function defined when this Log object was instantiated.

message is any arbitrary text.

nocallback is a boolean which if set to true prevents the callback.

W(message [, nocallback ])

Write a 'warning' message of the form "prefix⚠️ message" to the system log and, by default, pass a message of the form "message" to the warning callback function defined when this Log object was instantiated.

message is any arbitrary text.

nocallback is a boolean which if set to true prevents the callback.

E(message [, nocallback ])

Write an 'error' message of the form "prefix:error: message" to the system log and, by default, pass a message of the form "message" to the error callback function defined when this Log object was instantiated.

message is any arbitrary text.

nocallback is a boolean which if set to true prevents the callback.