https://github.com/uoregon-libraries/rais-image-server/wiki/Release-Notes#release-300
I posted about two years ago here about this project, but it's had some massive changes since then. Briefy, RAIS is a IIIF-compliant image server (see iiif.io). It conforms to level 2 of the IIIF Image API 2.1. This means you can put images somewhere, tell RAIS how to find them, and serve them up in a variety of ways. The primary use-case is hooking up OpenSeadragon (or a similar front-end application) to provide panning and zooming capabilities for images that are too big for effective downloading. But the IIIF Image spec also has a few interesting image manipulation options for things like on-demand thumbnail generation, image rotation, and cropping. A real-world example of RAIS in action can be seen at our Oregon Historic Newspapers website. For instance, https://oregonnews.uoregon.edu/lccn/sn83008376/2016-10-17/ed-1/seq-1/ - the tiles for that pan-and-zoom window are served up by RAIS. But RAIS (and most IIIF image servers) can do a lot more than just these pan-and-zoom views. Say, if you wanted a close look at a particular old-timey ad: https://oregonnews.uoregon.edu/images/iiif/batch_oru_elk_ver01%2Fdata%2Fsn84022653%2F00000000018%2F1876122301%2F0190.jp2/2180,2600,1310,730/max/0/default.jpg. Or maybe for some reason you want to reverse the headline of an article: https://oregonnews.uoregon.edu/images/iiif/batch_oru_20161212AggressiveStrudel_ver01%2Fdata%2Fsn85042482%2Fprint%2F2016090701%2F0009.jp2/1440,220,650,250/max/!0/default.jpg IIIF doesn't allow us to do complex image manipulations, but for most purposes we serve images on the web, it's a great option. And RAIS, written in Go with low-overhead C bindings to openjpeg, is quite possibly the fastest open-source IIIF server available for serving up JP2 images. It's also fast for other sources, but JP2 is where it truly shines. (For those who aren't aware, JP2 images are a high-quality, low-filesize format that is extremely memory-friendly: decoding part of a JP2 is possible without loading the entire thing into memory. They're slower to decode than any other image format we've considered, but they save us so much disk space that the performance costs are more than acceptable. JP2s can be 50% to 25% the size of a comparable JPG image while also giving us the partial-decode properties JPGs don't have) Though I don't love having system-level dependencies, the openjpeg bindings allow us to tout RAIS for its speed. Other IIIF servers either shell out to command-line applications or use C bindings that simply aren't as performant as Go's. Combine that with the high concurrency built right into the net/http package, and Go has turned out to be the perfect choice for this application. The geeky details gophers might appreciate that end-users probably won't: RAIS 3 now uses Go 1.11's modules. I am enjoying this approach. I miss "gb" some, but modules seem like a very acceptable compromise in the name of consistency. RAIS includes plugin support and has example plugins that do things like enable pulling from S3 on demand or adding DataDog middleware. Compile RAIS, compile your desired plugins, drop them into plugins/, and RAIS just runs them. I'm really liking plugins. RAIS includes a cache I found on hashicorp's github repo. For systems with a lot of RAM or with a small exhibit of images, tile caching is a huge win. But even on sites without so much RAM, the cache is fairly decent because it uses a 2Q LRU - which means it's not just throwing away the oldest items. Popularity of cached items is a factor for what stays cached, which is very interesting to me. As I mentioned two years ago, RAIS was my first Go project, and I had literally zero Go experience before being asked to look at it. It was originally a proof of concept and I had no idea what to do with it. Unlike every other "first project in a new tech/framework/language", RAIS has been easy to maintain and keep running since its inception. RAIS has now been in production and gotten maintenance on and off for four years. I think that speaks volumes to the power of simplicity, something Go offers that I just don't feel I can find anywhere else. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
