Front End Optimization Test

The HTTP protocols that underlie web applications were originally developed to support the transmission and rendering of simple webpages. New technologies such as JavaScript and cascading style sheets (CSS), and new media types such as Flash videos and graphics-rich images, place heavy demands on front-end performance, that is, on performance at the browser level.

The Citrix ADC front end optimization (FEO) feature addresses such issues and reduces the load time and render time of webpages by:

Reducing the number of requests;
Reducing the number of bytes required for rendering each page.
Reducing the number of bytes in page responses.
Simplifying and optimizing the content served to the client browser.

Citrix ADCs support numerous web content optimizations for both desktop and mobile users. These optimizations include inlining, minification, image optimization, repositioning, and connection management. To ascertain the effectiveness of these optimizations, administrators can periodically run the Front End Optimization test, measure how many optimizations of what types were applied in the recent past and how much data was saved in the process.

Target of the test : A Citrix ADC VPX/MPX

Agent deploying the test : A remote agent

Outputs of the test : One set of results for the Citrix ADC being monitored

Configurable parameters for the test
Parameter	Description
Test Period	How often should the test be executed.
Host	The IP address of the host for which the test is being configured.
NetScaler Username, NetScaler Password, and Confirm Password	To monitor a NetScaler device, the eG agent should be configured with the credentials of a user with read-only privileges to the target NetScaler device. Specify the credentials of such a user in the NetScaler Username and NetScaler Password text boxes. Then, confirm the password by retyping it in the Confirm Password text box.
SSL	The eG agent collects performance metrics by invoking NITRO (NetScaler Interface Through Restful interfaces and Objects) APIs on the target NetScaler device. Typically, the NITRO APIs can be invoked through the HTTP or the HTTPS mode. By default, the eG agent invokes the NITRO APIs using the HTTPS mode. This is why, the SSL flag is set to Yes by default. If the target NetScaler device is not SSL-enabled, then the NITRO APIs can be accessed through the HTTP mode only. In this case, set the SSL flag to No.

Measurements made by the test
Measurement	Description	Measurement Unit	Interpretation
Images resized	Indicates the number of resized images during the last measurement period.	Number	Image optimization reduces the image to the size indicated in the image tag by Citrix ADC, enabling client browsers to load images faster.
Images convert from gif to pngs	Indicates the number of images that were converted from GIF to PNG format during the last measurement period.	Number
Jpegs images optimized	Indicates the number of JPEG images that were optimized during the last measurement period.	Number	JPEG optimization removes non-image data, such as comments, from JPEG images.
Images convert to webp format	Indicates the number of images that were converted to webp format.	Number	This optimization converts JPEG, GIF, PNG image formats to WEBP format.
Images convert to jpegxr format	Indicates the number of images that were converted to JXR format.	Number
CSS minified	Indicates the total number of CSS files that were minified during the last measurement period.	Number	To minify a CSS file is to remove comments and whitespaces from that CSS file.
JS minified	Indicates the total number of JavaScript files that were minified during the last measurement period.	Number	To minify a JS file is to remove comments and whitespaces from that JS file.
CSS moved to head	Indicates the number of CSS files that were moved to <head> tag in the last measurement period.	Number	You can move any CSS file present within the body tag of an HTML page to the head tag to reduce page rendering time.
JS moved to end	Indicates the number of JS files that were moved to the end during the last measurement period.	Number	You can move any JavaScript file present in the body tag to the end of the body tag to optimize page rendering.
Import to links	Indicates the number of CSS imports converted to links during the last measurement period.	Number	A non-zero value for this measure indicates that one/more CSS import statements have been converted to HTML link tags.
CSS combined	Indicates the total number of CSS combined during the last measurement period.	Number	A non-zero value for this measure indicates that one/more CSS files have been combined into one file.
Objects cache extended	Indicates the number of objects cache extended during the last measurement period.	Number	The value of this measure will be incremented if one/more cached objects are configured to be used by the browser for an extended period of time.
HTML comments removed	Indicates the number of HTML comments that were removed during the last measurement period.	Number
Data savings	Indicates the total data savings in the last measurement period.	MB	A high value for this measure indicates that the optimizations in place are effective. Therefore, a high value is desired for this measure.
Inlined images	Indicates the total number of inlined images in HTML during the last measurement period.	Number	A non-zero value is reported by this measure if one/more inline images less than 2KB in size are found in HTML.
Inlined CSS	Indicates the number of inlined CSS files during the last measurement period.	Number	A non-zero value is reported by this measure if one/more CSS files, whose size is less than 2KB, are found within the main page.
Inlined JS	Indicates the number of inlined JS files in the last measurement period.	Number	The value of this measure is incremented if one/more linked JavaScript files (less than 2KB) are converted to inline JavaScript files.
Inlined images in CSS	Indicates the number of inlined images in CSS during the last measurement period.	Number	If one/more inline small images (less than 2KB) are referred within CSS files as background-URLs, then the value of this measure will be incremented.
URI replaced	Indicates the total number of URIs that were replaced during the last measurement period.	Number
Images lazy loaded	Indicates the number of images that were loaded lazily during the last measurement period.	Number	Lazy load images are those that are downloaded only when the user scrolls the page to view them.
Domain sharded	Indicates how many images in the last measurement period have a domain that has been set from shards.	Number
Original cache objects	Indicates the number of original cache objects that were ready to be served during the last measurement period.	Number
Optimized cache objects	Indicates the number of optimized cache objects ready to be served during the last measurement period.	Number	If the value of this measure is equal to or very close to that of the Original cache objects measure, it means that the optimization techniques applied are effective.