FIT 14.3.1: Web Accelerator and RDL Update

Today we have released version 14.3.1 of our FIT software, including updates for the Web Accelerator and Rapid Development Layer

We have learned a lot from analyzing our image traffic. Therefore, this minor release focusses on bug fixes and enhancements of image processing.

Many images are small enough, in terms of dimensions, to fit into current clients’ viewports. That is because many mobile devices have high density displays (e.g. Apple’s retina display) resulting in lots of pixels. Those images don’t need to be scaled. Therefore, Image Scaling and Compression are now separately configurable. This can be useful for CSS documents with image sprites that should not be scaled but still be compressed.

If an image is known to be small enough for the requesting client, FIT will automatically switch from Image Scaling to Image Compression. The latter uses image URLs without sizing parameters, resulting in a better cache hit rate (in FIT and in downstream caches) and reduced disk and CPU usage.

Another finding in our image statistics is that in certain cases image weight (i.e. file size) may be increased by our image processing. Now, the smaller original image will be sent to the client instead of the processed image. We call that pass-on-enlargement. Since animated GIF images are hard to optimize and are practically never scaled, they are no longer processed at all.

We have further improved SVG as a replacement for transparent PNGs (also known as “zorro”). The alpha map is smaller. And a bug showing artifacts at image borders was fixed.

Developers will find some interesting enhancements, too. The content DC properties for example let you run Flow actions depending on the type of content (e.g. html or js). The detection page can now be disabled on a per-URL basis.

The SDK for 14.3.1 is available from Github.

Refer to the full changelog for a more detailed list of changes.