pip-services3-components-node/src/info/ContextInfo.ts

Component definitions for Pip.Services in Node.js

/** @module info */
/** @hidden */ 
let os = require('os');

import { StringValueMap } from 'pip-services3-commons-node';
import { ConfigParams } from 'pip-services3-commons-node';
import { IReconfigurable } from 'pip-services3-commons-node';

/**
 * Context information component that provides detail information
 * about execution context: container or/and process.
 * 
 * Most often ContextInfo is used by logging and performance counters
 * to identify source of the collected logs and metrics.
 * 
 * ### Configuration parameters ###
 * 
 * - name: 					the context (container or process) name
 * - description: 		   	human-readable description of the context
 * - properties: 			entire section of additional descriptive properties
 * - ...
 * 
 * ### Example ###
 * 
 *     let contextInfo = new ContextInfo();
 *     contextInfo.configure(ConfigParams.fromTuples(
 *         "name", "MyMicroservice",
 *         "description", "My first microservice"
 *     ));
 *     
 *     context.name;			// Result: "MyMicroservice"
 *     context.contextId;		// Possible result: "mylaptop"
 *     context.startTime;		// Possible result: 2018-01-01:22:12:23.45Z
 *     context.uptime;			// Possible result: 3454345
 */
export class ContextInfo implements IReconfigurable {	
	private _name: string = "unknown";
	private _description: string = null;
	private _contextId: string = os.hostname(); // IdGenerator.nextLong();
	private _startTime: Date = new Date();
	private _properties: StringValueMap = new StringValueMap();

	/**
	 * Creates a new instance of this context info.
	 * 
	 * @param name  		(optional) a context name.
	 * @param description 	(optional) a human-readable description of the context.
	 */
	public constructor(name?: string, description?: string) {
		this._name = name || "unknown";
		this._description = description || null;
	}

	/**
     * Configures component by passing configuration parameters.
     * 
     * @param config    configuration parameters to be set.
	 */
	public configure(config: ConfigParams): void {
		this.name = config.getAsStringWithDefault("name", this.name);
		this.description = config.getAsStringWithDefault("description", this.description);		
		this.properties = config.getSection("properties");
	}
	
	/**
	 * Gets the context name.
	 * 
	 * @returns the context name 
	 */
	public get name(): string { return this._name; }

	/** 
	 * Sets the context name.
	 *  
	 * @param value		a new name for the context.
	 */
	public set name(value: string) { this._name = value || "unknown"; }
	
	/**
	 * Gets the human-readable description of the context.
	 * 
	 * @returns the human-readable description of the context.
	 */
	public get description(): string { return this._description; }

	/**
	 * Sets the human-readable description of the context.
	 * 
	 * @param value a new human readable description of the context.
	 */
	public set description(value: string) { this._description = value; }
	
	/**
	 * Gets the unique context id.
	 * Usually it is the current host name.
	 * 
	 * @returns the unique context id.
	 */
	public get contextId(): string { return this._contextId; }

	/**
	 * Sets the unique context id.
	 * 
	 * @param value a new unique context id.
	 */
	public set contextId(value: string) { this._contextId = value; }
	
	/**
	 * Gets the context start time.
	 * 
	 * @returns the context start time.
	 */
	public get startTime(): Date { return this._startTime; }

	/**
	 * Sets the context start time.
	 * 
	 * @param value a new context start time.
	 */
	public set startTime(value: Date) { this._startTime = value || new Date(); }

	/**
	 * Calculates the context uptime as from the start time.
	 * 
	 * @returns number of milliseconds from the context start time.
	 */
	public get uptime(): number {
		return new Date().getTime() - this._startTime.getTime();
	}

	/**
	 * Gets context additional parameters.
	 * 
	 * @returns a JSON object with additional context parameters.
	 */
	public get properties(): any { return this._properties; }

	/** 
	 * Sets context additional parameters.
	 * 
	 * @param properties 	a JSON object with context additional parameters
	*/
	public set properties(properties: any) {
		this._properties = StringValueMap.fromValue(properties);
	}
	
	/**
	 * Creates a new ContextInfo and sets its configuration parameters.
	 * 
	 * @param config 	configuration parameters for the new ContextInfo.
	 * @returns a newly created ContextInfo
	 */
	public static fromConfig(config: ConfigParams): ContextInfo {
		let result = new ContextInfo();
		result.configure(config);
		return result;
	}
}