JavaScript Wrapper - Report Example

JavaScript Wrapper Research Project 4th October Table of Contents Table of Contents Introduction 2 Communication Paths 4 WireShark 5 Installation 5 Items Cached in Squid Proxy 5 Common Programming Errors 6 Introduction JavaScript JavaScript is an open scripting language. It is not intended to replace proper security measures, and it is not favorable where proper encryption is required. JavaScript has its own security model, which is not designed to protect neither the web-site owner nor the data passed between the client and the server. The security model is designed to protect the user from malicious web-sites, and, hence, it enforces strict limits on what the page author is allowed to do. It is possible to have control over one’s own page inside the browser, but that is where such abilities end. JavaScript API Wrapper Main purpose of an API Wrapper is to facilitate making API requests over HTTP to a system built on Wave Framework. API Wrapper class does everything for the developer without requiring the developer to learn the ins and outs of technical details about how to build an API request. API Wrapper does a lot of thing for the developer and takes the web browser options into account, but there are still a couple of things that should be considered when using the Wrapper. It requires JSON support on the web browser for various functionalities, such as for hash validations. API Wrapper makes requests by default using XMLHttpRequest, but not asynchronously. Asynchronous requests are also possible. Requests gather data from one of two places: Either directly as input or using an existing form on the page, latter of which allows for file uploads. JavaScript API Wrapper submits files using hidden iFrames. This API Wrapper has been tested and must work with all modern web browsers. Wrapper should work without problems on latest versions of Google Chrome, Mozilla Firefox, Apple Safari, Opera and Internet Explorer. JavaScript Salesforce API Wrapper Salesforce API provides programmatic access to an organization’s information and allows developers to implement custom functionality. Salesforce is a leader in on-demand Customer Relationship Management (CRM) services. Very organizations trust their vital customer and sales data to salesforce.com than any other on-demand CRM company. The Apex platform and API extends Salesforce and the AppExchange is a directory of on-demand applications (ProgrammableWeb.com, 2012). The Force.com web services API allows users to create, retrieve, update or delete records, such as accounts, leads, and custom objects. With more than 20 different calls, the API also allows users to maintain passwords, perform searches, and much more. Communication Paths The HTML page has content that communicate with the content and vise verse. There are two communication directions. The web page calls functions inside the Salesforce content. The Salesforce content calls functions inside the web page. Each of these communication directions is described in detail below: Calling Content Functions from the Web Page The Salesforce object has a function SendMessage that can be called from a web page in order to call functions within Salesforce content. This function is very similar to the GameObject.SendMessage function in the Salesforce scripting API. When called from an object name, function name and a single argument, and SendMessage. We call the given function in the given GameObject. In order to call the Salesforce web Player’s SendMessage function you must first get a reference to the Salesforce player object. WireShark WireShark is in Salesforce used to inspect data passing through the web page. WireShark has the ability to capture all the fishy packets that are sent to the web page and it records them for analysis. WireShark hunts those packets in the TCP/IP layer during transmission and keeps whatever it finds. It’s important to keep WireShark in mind if you are a network admin to double check that your entire customer’s sensitive data is being transmitted securely. On the other the system watches out for those sharks using the tools on open networks. Installation You run WireShark through gksudo WireShark terminal or sudo WireShark for graphical applications. Under the “Capture” you can choose the device you want to sniff. At the top of the application there is a button capture options where you can customize your captures. Under the interface list you will see one of your devices sending or receiving packets this is your active one. Click options customized, and then click “Start”. This will take you a new pane that will show you the packets that are being captured by WireShark. Items Cached in Squid Proxy Squid handles caching and exposes the directives using squid.conf, so that it can control how much should be cached and what should be given the highest priority while caching. Types of objects which are cached include: In-transit Objects or Current Requests These are the objects related to the current requests and they have the highest priority kept in the cache space in the RAM. These objects must be kept in RAM and if there is a situation where the incoming request rate is quite high and we are about to overflow the cache space in RAM, Squid will try to keep the served part (the part which has already been sent to the client) on the disk to create free space in RAM. Hot or Popular Objects These objects or web documents are popular and are requested quite frequently compared to others. These are stored in the cache space left after storing the in-transit objects as these have a lower priority than in-transit objects. These objects are generally pushed to disk when there is a need to generate more in RAM cache space for storing the in-transit objects. Negatively Cached Objects Negatively cached objects are error messages which Squid encounters while fetching a page or web document on behalf of a client. For example, if a request to a web page has resulted in a HTTP error 404 (page not found), and Squid receives a subsequent request for the same web page, then Squid will check if the response is still fresh and will return a reply from the cache itself. If there is a request for the same page after the negatively cached object corresponding to that page has expired, Squid will check again if the page is available. They have the same priority as hot or popular objects and they can be pushed to disk at any time in favor of in-transit objects. Common Programming Errors There is a wide variety of errors that can occur during the execution of a script and they can be grouped into three classes namely: syntax errors, runtime errors, and semantic errors. Syntax Errors They occur when you write code that violates the rules of the JavaScript language. For example, writing the following, var x = y + * z; is a syntax error because the syntax of the * operator requires two expressions to operate upon, and “y +” does not constitute a valid expression. Another example is var myString = "This string doesnt terminate because the string literal isn’t properly quoted. Syntax errors are fairly easy to catch because they are immediately evident when the script is parsed before being executed. However the interpreter can make some sort of assumption about what the programmer intended and can continue to execute the rest of the script. Even if they do run in some manner, as they do not constitute a valid program and their behavior can therefore be erratic, destructive, or otherwise anomalous. You can easily avoid syntax errors by turning on error warnings in the browser and then loading the script or by using one of the wide variety of debuggers available. Runtime Errors These are errors that occur (as the name suggests) while the script is running. These errors result from JavaScript that has the correct syntax but encounters a problem in its execution environment. Mainly runtime errors result from trying to access a variable, property, method, or object that does not exist or from attempting to utilize a resource that is not available. Some runtime errors can be found by examination of source code. For example, window.allert("Hi there"); results in a runtime error because there is no allert() method of the Window object. This example constitutes perfectly legal JavaScript, but the interpreter cannot tell until runtime that invoking window.allert() is invalid, because such a method might have been added as an instance property at some previous point during execution. Other kinds of runtime errors cannot be caught by examination of source code. For example, while the following might appear to be error-free, var products = ["Widgets", "Snarks", "Phasers"]; var choice = parseInt(prompt("Enter the number of the product you are interested in")); alert(“You chose: " + products[choice]); what happens if the user enters a negative value for choice? A runtime error indicating the array index is out of bounds. Although some defensive programming can help here, var products = ["Widgets", "Snarks", "Phasers"]; var choice = parseInt(prompt("Enter the number of the product in which you are interested")); if (choice >>= 0 && choice Read More