Caching

Caching Issues

About

List of files for which we need to define proper cache busting and expires headers.

Attempt to minimize server requests (through proper expire headers), while also ensuring that user sees latest file and doesn't need to perform Shift+Reload.

File sets

1. Top level files, user's entry point into app (i.e. pagedesigner.html, review.html)

   • expires header: 24 hours

2. App files (JS, HTML, CSS)

   The build process should place each set of files in a versioned directory. When updated, version changes in URL, forcing browser to bypass cache and load files from server.

   • Maqetta files

     • URL: http://host/maqetta/app/davinci/<revision>/davinci.js

       where revision is the first 7 characters of the Git hash from which the build was produced.

   • Dojo library

     • URL: http://host/maqetta/app/dojo/<version>/dojo.js

     • URL: http://host/maqetta/app/dijit/<version>/dijit.js

       where version is the version number of the Dojo lib (i.e. 1.6, 1.7b2, 1.7.0.1, ...). Don't use Git hash here, since it's possible that a new Maqetta version will keep the same Dojo version. By using the Dojo version, we avoid having users request the Dojo files again, when they haven't changed.

   • expires header: 1 year

3. User workspace files, in particular lib & theme

   User can change URL for lib files, so cannot depend on version string as part of URL path. Instead, we must rely on URL parameters.

   • read-only files (libs and themes)

     • URL: http://host/maqetta/user/<userId>/ws/workspace/lib/dojo/dojo/resources/blank.gif?v=<libVersion>

     • URL: http://host/maqetta/user/<userId>/ws/workspace/themes/claro/form/images/button.png?v=<themeVersion>

       where libVersion and themeVersion are the version string for that particular library/theme. As in the App files section, this cuts down on unnecessary server requests.

   • editable files (user's files and custom themes)

     • URL: http://host/maqetta/user/<userId>/ws/workspace/themes/myclaro/myclaro.css?v=<revision>

       where revision is a generated number. Every time user updates custom theme, number gets regenerated (increment or random). This way, user is sure to get latest files (cache busted by newly generated number); but if no changes, then files are pulled from cache.

       does this mean that source view (model) shows @import "app.css" but under the hood we stuff the following relative URL into the iframe: @import "app.css?v=<revision>"? Will things work when using @import? Note that we also need to bust the cache for preview-in-browser. We have caching bugs now where changes to app.css don't register in preview-in-browser unless user clears his browser cache.

   • expires header: 1 year

4. Preview

   • cache headers: no caching

     Preview should reflect the very latest state of the file, therefore we must set headers to disable caching preview files.

5. Review and commenting - The list of reviews is subject to caching bugs. If you have had a review session previously, and then get another review invitation and follow the link, sometimes the list of reviews doesn't show the latest review session. If you navigate away from the review page, clear your browser cache, and go back to the review link, then the new review session will show.

   • Not sure how to fix yet

6. REST APIs

   • URL: http://host/maqetta/cmd/loadFile?path=.%2Fapp.css

   Do we need to do anything with these? Since we always want non-stale data, could be just as simple as appending a URL param with latest time in milliseconds. Or, if using Dojo's XHR methods, set the preventCache argument (which also just sets a URL param).