JavaScript programming language

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JavaScript programming language

The idea is simple... a topic map store (that is, back-end) that talks to the web front-end by means of JSON and said front-end being nothing else than a basic HTML-layout and jQuery taking care of the UI dynamics. Take that, Flex! ;-)

The code below has all the usual object-oriented JavaScript patterns, e.g.:

• namespaces (simulated by using dictionaries)
• private members (made by the constructor, varS and parameters of the constructor become the private members)
• public (prototype) methods
• public members (using the constructor's this variable)
• privileged methods (assigned with this in the constructor, e.g., this.method = function() { };)
• Observer pattern (to notify the UI-components of any changes)

All of the above goodness is made possible because of closures (that is, an inner function can access the variables and parameters of its outer function, even after the outer function has finished executing).

JavaScript topic map objects

// setting up Base (infrastructure) namespace
var Base = {};

// observer pattern
Base.Subject = function(subject) {
    // private members
    var observers = new Array();    
    
    // privileged methods
    this.addObserver = function(observer) {
        observers.push(observer);
    }

    this.removeObserver = function(observer) {
        // missing code
    }

    this.notifyObserver = function() {
        // http://www.prototypejs.org/api/array
        for (var i = 0, len = observers.length; i < len; ++i) {
            var observer = observers[i];
            // TODO: check.
            observer.update(subject);
        }
    }
}

// public (prototype) methods of Base.Subject object

// ======================================================================

// setting up Utilities namespace
var Utilities = {};

Utilities.defaultHandler = function(defaults, params) {
    var i;
    for (i in params) {
        defaults[i] = params[i];
    }
    return defaults;
} 

Utilities.S4 = function() {
    return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
}

Utilities.guid = function() {
    return (Utilities.S4() + 
        Utilities.S4() + "-" + 
        Utilities.S4() + "-" + 
        Utilities.S4() + "-" + 
        Utilities.S4() + "-" + 
        Utilities.S4() + 
        Utilities.S4() + 
        Utilities.S4());
}

Utilities.sanitizeId = function(identifier) {
    return identifier.replace(/ /gi, identifier).toLowerCase();
}

// setting up Topicmap.Models namespace
var Topicmap = {};
Topicmap.Models = {};

// ======================================================================

Topicmap.Models.Node = function(obj) {
    // private members
    var that = this;
    var params = 
      Utilities.defaultHandler({identifier: Utilities.guid(), instanceOf: 'node'}, obj);
    var identifier = Utilities.sanitizeId(params['identifier']);
    
    // priviliged methods
    this.getId = function() {
        return identifier;
    }
    
    // public properties
    this.instanceOf = Utilities.sanitizeId(params['instanceOf']);
}

// public (prototype) methods of Node object
Topicmap.Models.Node.prototype.getIdentifier = function() {
    return this.getId();
}

// ======================================================================

Topicmap.Models.Topic = function(obj) {
    // private members
    var params = Utilities.defaultHandler({
        identifier: Utilities.guid(), 
        instanceOf: 'topic', 
        baseName: 'unknown'}, obj);
    
    // call to super constructor
    Topicmap.Models.Node.call(this, {
        identifier: params['identifier'], 
        instanceOf: params['instanceOf']}, obj);
    
    var baseNames = new Array();
    baseNames.push(params['baseName']);
    
    this.subject = new Base.Subject(this);
    
    // privileged methods
    this.getBaseName = function(index) {
        return baseNames[index];
    }
    
    this.getBaseNames = function() {
        return baseNames;        
    }
    
    // public properties
}

// setting up inheritance: Topic extends Node
Topicmap.Models.Topic.prototype = new Topicmap.Models.Node();

Topicmap.Models.Topic.prototype.constructor = Topicmap.Models.Topic;

// public (prototype) methods of Topic object
Topicmap.Models.Topic.prototype.getFirstName = function() {    
    return this.getBaseName(0);
}

Topicmap.Models.Topic.prototype.addBaseName = function(baseName) {
    this.getBaseNames().push(baseName);
    this.subject.notifyObserver();
}

Topicmap.Models.Topic.prototype.removeBaseName = function() {
    // TODO: implement
}

Topicmap.Models.Topic.prototype.clearBaseNames = function() {
    // TODO: implement
}

Topicmap.Models.Topic.prototype.addOccurrence = function() {
    // TODO: implement
}

// ======================================================================

Topicmap.Models.Occurrence = function(obj) {
    // private members
    var params = Utilities.defaultHandler({
        identifier: Utilities.guid(), 
        instanceOf: 'occurrence',
        topicIdentifier: null,
        scope: '*',
        resourceRef: ''}, obj);
    
    // call to super constructor
    Topicmap.Models.Node.call(this, {
        identifier: params['identifier'], 
        instanceOf: params['instanceOf']}, obj);
    
    // public properties
    this.topicIdentifier = Utilities.sanitizeId(params['topicIdentifier']);
    this.scope = Utilities.sanitizeId(params['scope']);
    this.resourceRef = params['resourceRef'];  
}

// setting up inheritance: Occurrence extends Node
Topicmap.Models.Occurrence.prototype = new Topicmap.Models.Node();
Topicmap.Models.Occurrence.prototype.constructor = Topicmap.Models.Occurrence;

// ======================================================================

Topicmap.Models.Member = function(obj) {
    // private members
    var params = Utilities.defaultHandler({
        roleSpec: '', topicRef: '', 
        identifier: Utilities.guid()}, obj);
    var identifier = Utilities.sanitizeId(params['identifier']);    
    var topicRefs = new Array();
    
    topicRefs.push(Utilities.sanitizeId(params['topicRef']));
    
    // priviliged methods
    this.getIdentifier = function() {
        return identifier;
    }
    
    this.getTopicRefs = function() {
        return topicRefs;
    }
    
    this.addTopicRef = function(topicRef) {
        topicRefs.push(topicRef);
    }
    
    this.removeTopicRef = function(topicRef) {
        // TODO: implement code
    }
    
    this.clearTopicRefs = function() {
        // TODO: implement code
    }
    
    // public properties
    this.roleSpec = Utilities.sanitizeId(params['roleSpec']);
}

// public (prototype) methods of Member object

// ======================================================================

Topicmap.Models.Association = function(obj) {
    // private members
    var params = Utilities.defaultHandler({
        srcRoleSpec: '', 
        srcTopicRef: '', 
        destRoleSpec: '',
        destTopicRef: '',
        identifier: Utilities.guid(),
        instanceOf: 'association',
        scope: '*',
        baseName: 'unknown'}, obj);
    
    // call to super constructor
    Topicmap.Models.Topic.call(this, {
        identifier: Utilities.sanitizeId(params['identifier']), 
        instanceOf: Utilities.sanitizeId(params['instanceOf']), 
        baseName: params['baseName']}, obj);
    
    var members = new Array();
    
    var srcMember = new Topicmap.Models.Member({
      roleSpec: Utilities.sanitizeId(params['srcRoleSpec']), 
      topicRef: Utilities.sanitizeId(params['srcTopicRef'])});
    var destMember = new Topicmap.Models.Member({
      roleSpec: Utilities.sanitizeId(params['destRoleSpec']), 
      topicRef: Utilities.sanitizeId(params['destTopicRef'])});
    members.push(srcMember);
    members.push(destMember);    
    
    // priviliged methods
    this.createMember = function(roleSpec, topicRef) {
        var member = new Topicmap.Models.Member({
          roleSpec: Utilities.sanitizeId(params['roleSpec']), 
          topicRef: Utilities.sanitizeId(params['topicRef'])});
        members.push(member);
    }
    
    this.createMembers = function(srcRoleSpec, srcTopicRef, destRoleSpec, destTopicRef) {
        var srcMember = new Topicmap.Models.Member({
          roleSpec: Utilities.sanitizeId(srcRoleSpec), 
          topicRef: Utilities.sanitizeId(srcTopicRef)});
        var destMember = new Topicmap.Models.Member({
          roleSpec: Utilities.sanitizeId(destRoleSpec), 
          topicRef: Utilities.sanitizeId(destTopicRef)});
        members.push(srcMember);
        members.push(destMember);
    }
    
    this.addMember = function(member) {
        members.push(member);
    }
    
    this.getMember = function(identifier) {
        // TODO: implement code
    }
    
    this.getMembers = function() {
        return members;
    }
    
    this.removeMember = function(identifer) {
        // TODO: implement code
    }
    
    this.removeMembers = function() {
        // TODO: implement code
    }
    
    // public properties
    this.scope = Utilities.sanitizeId(params['scope']);
}

// setting up inheritance: Association extends Topic
Topicmap.Models.Association.prototype = new Topicmap.Models.Topic();
Topicmap.Models.Association.prototype.constructor = Topicmap.Models.Association;

// ======================================================================

Topicmap.Models.MetaDatum = function(obj) {
  // private members
    var params = Utilities.defaultHandler({
        parentIdentifier: '', 
        name: '', 
        value: '',
        identifier: Utilities.guid(),
        scope: '*'}, obj);
    var parentIdentifier = Utilities.sanitizeId(params['parentIdentifier']);
    var name = Utilities.sanitizeId(params['name']);
    var identifier = Utilities.sanitizeId(params['identifier']);
    
    // priviliged methods
    this.getParentIdentifier = function() {
        return parentIdentifier;
    }
    
    this.getIdentifier = function() {
        return identifier;
    }
    
    this.getName = function() {
        return name;
    }
    
    // public properties
    this.value = params['value'];
    this.scope = params['scope'];
}

// ======================================================================

Topicmap.Models.Map = function() {    
    // privileged methods
    this.update = function(subject) {
        // TODO: show type of object that has been created or updated; either 
        // Topic or Association
        console.log("The following subject has changed: [%s]", subject.getIdentifier());
    }
}