The mid tier, AJAX, and KITE
AJAX is a group of interrelated web development methods used on the client side to create interactive web applications. With AJAX, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page. AJAX uses a combination of HTML and CSS to mark up and style information. The Document Object Model (DOM) is accessed with JavaScript to dynamically display and allow the user to interact with the information presented. JavaScript and the XMLHttpRequest object provide a method for exchanging data asynchronously between the browser and server to avoid full-page reloads.
AJAX allows web-based applications to migrate from a page model to a true application model based on events and user actions. Using AJAX, a web application can request only the dynamic content that is needed to update the page, and reduce bandwidth usage and load time. This AJAX functionality can make it difficult for performance tools to detect when a web page has finished loading.
In a typical AJAX web application, the initial HTTP request is usually answered with an HTML response that includes the user interface portion of the application. This response might include supporting resources that the browser needs to load in subsequent requests. The JavaScript is executed during the page load completion event.
When the JavaScript is executed, additional server requests are made via XMLHttpRequest calls. Responses to these asynchronous calls are reflected by a modification to the initial downloaded page. Because the concept of pages does not apply to most AJAX web applications, it might be difficult to determine when to allow sequential web page actions and page completion.
Some Mid Tier pages contain static data (user interface elements and JavaScript event handling scripts) and dynamic data (web page form content specific to the request). The Mid Tierseparates the static data from the dynamic data and delivers each separately. Static data is delivered via a normal HTTP request. Dynamic data is delivered via AJAX calls. These AJAX calls present challenges to Mid Tier KITE scripting because the page completion event is the basis for a successful test script and for any measurement based on that event.
Most automation and testing tools, including KITE, encounter synchronization problems during page load events. For information about AJAX, see the AJAX documentation from W3Schools.