Goodbye Applets: Sunset Plans for Legacy UIs: Applets from a practitioner’s perspective with timeless lessons.
Browsers are moving fast and patience for spinning coffee cups is gone. Java applets once felt like magic. Now they feel like someone asking you to install a toolbar. With IE7 rolling out through Windows Update, Firefox 2 everywhere, Vista shouting with UAC prompts, and corporate desktops locked down, the writing is on the wall. The plugin still works, but the experience fights users at every step. It is time to plan a sunset for legacy UI pieces built on applets and move toward friendlier options.
Definitions
Applet: a small Java program that runs inside the browser through the JRE plugin. It loads bytecode, kicks the virtual machine, and paints a custom UI inside a rectangle on the page.
Cold start: the first time the browser needs the JRE in a session. You get a noticeable pause while the VM wakes up. On older machines this feels like a coffee break.
Sandbox and signed applet: by default, applets are jailed. To reach the file system or clipboard, you sign the applet and the user gets a scary dialog that most people do not understand. Many offices train staff to click No.
Alternatives: AJAX with modern JavaScript and DOM, Flash Player 9 with Flex or OpenLaszlo, emerging WPF E previews from Microsoft, and for desktop style delivery, Java Web Start.
Examples
File uploads and forms. We used applets for multi file upload because browsers only offered one box at a time. Today, scripted forms can add multiple inputs on the fly and queue uploads. If you truly need drag and drop from the desktop, Flash handles that better in practice since the prompt is simpler and installed more often.
Charts and dashboards. Interactive charts in applets looked sharp but required the JRE. Consider server rendered PNGs for simple cases, and swap in Flash or canvas style shims for interaction. Toolkits like Dojo and Prototype help with behaviors, and jQuery is getting traction for simpler DOM work.
Rich data grids. Applets gave us scrollable tables, sorting, and copy to clipboard. A modern approach uses AJAX calls, JSON payloads, and pagination. GWT converts Java to JavaScript and ships solid widgets if your team is already in Java land.
Media and real time updates. Video streaming belongs to Flash. Live stock ticks or chat can run with long polling over AJAX. Applets no longer buy much here unless you need direct sockets and no proxy issues, which is rare for public sites.
Counterexamples
Controlled intranets with a blessed JRE. If every desktop has the same JRE and the help desk owns the image, an applet that talks to local hardware still makes sense.
Smart cards and scanners. When you must hit drivers or custom ports from the page, a signed applet can be the simplest path, as long as the user base is trained to accept the certificate and you manage renewals.
Thick tools that deserve a launcher. If the UI is more like an application than a page, move it to Java Web Start. You get versioning, desktop shortcuts, and no browser plugin headaches.
Decision rubric
- Audience. Do they control their machine or sit under strict IT rules with old JRE 1.4 builds
- Friction budget. How many prompts or installers will users tolerate before they bail
- Reach. Is this public web, partner portal, or locked intranet
- Performance. Is cold start time acceptable on older hardware
- Security. Do you require file system access or clipboard write The moment you sign an applet, expect fear dialogs
- Maintenance. Who will chase JRE updates, expired certs, and plugin quirks across IE6, IE7, and Firefox 2
- Alternatives. Can AJAX or Flash deliver the same feature with fewer blockers
- Offline story. If offline is a must, does a desktop launcher or sync client fit better than a page
Lesson learned
The web rewards the lowest barrier. Applets add barriers at every turn. Fresh installs, cold starts, warnings, and version roulette all chip away at trust. HTML plus JavaScript gets you reach with no pop ups or scary dialogs. Flash picks up the gaps with rich media and snappy widgets. If you really need Java, push it out of the page with Java Web Start and let the browser breathe.
Plan your sunset. Freeze new applet work. Wrap existing applets with clear fallbacks. Start a rewrite path that targets standards first and plugins second. Keep an eye on the WPF E story from Microsoft, but do not wait for a silver bullet. The practical move right now is to ship fewer prompts and more value.
We got a lot of mileage from applets. They taught us event loops, UI threading, and painting pixels. The web moved on. Our users did too. The kind move is to follow them with lightweight pages, predictable behavior, and upgrades that do not ask for trust before delivering value. Say thanks to applets, then ship without them.