Did you know that AL supports partial deployment of apps from Visual Studio Code? Check out the video to see how to get a RAD experience:
If you’ve ever worked in Visual Studio Code with AL, you might have noticed a small, somewhat mysterious file that appears in your project called rad.json. In this video, Erik explains what RAD (Rapid Application Development) publishing is, how it works, and why you should be using it — especially when working on large Business Central projects.
The Problem: Slow Deployments on Large Projects
When you’re working on a sizable AL project and you deploy it — say, to a Docker container — the entire app gets packaged up and sent to the server. Even for a moderately sized app, this can take 11 seconds or more. For truly large apps like Base Application, this deployment time can stretch into minutes.
Every time you make a small change — tweaking a single page, adjusting a field — you have to wait for that entire deployment cycle. That’s a lot of wasted time sitting around when you’re trying to iterate quickly.
Enter RAD: Rapid Application Development Publishing
Microsoft came up with RAD publishing largely to help their own developers who work on Base Application, which is enormous. The concept is simple: instead of repackaging and deploying your entire app every time you make a change, RAD tracks what has changed and only sends the modified files to the server.
How the rad.json File Works
The rad.json file sits in your project and tracks three categories of changes:
- Added — new files
- Modified — changed files
- Removed — deleted files
When you make a change to a file and save it, nothing happens in rad.json yet. But when you build the app (using Ctrl+Alt+B), the file updates to reflect which objects have been modified since the last deployment.
The Key Difference: Alt+F5 vs. F5 vs. Ctrl+F5
This is where the magic happens, and it all comes down to which keyboard shortcut you use:
- Alt+F5 — RAD publish. Only the changed files are packaged and sent to the server. In Erik’s demo, this brought deployment time down from 11 seconds to just 2 seconds.
- F5 — Standard publish with debugging. Sends the entire app.
- Ctrl+F5 — Publish without debugging. Also sends the entire app.
After a RAD publish completes, the rad.json file resets — there’s no longer any difference between what you have locally and what’s deployed on the server.
What Happens Behind the Scenes
When you use Alt+F5, only the modified object (for example, a single page) is packaged up and sent to the server. The server only needs to receive and compile that one object, rather than processing the entire application. That’s why the deployment is so dramatically faster.
When to Use RAD vs. Full Publish
- Use Alt+F5 (RAD) when you’re iterating on individual objects — tweaking a page layout, adjusting code in a codeunit, testing small changes.
- Use a full publish (F5 or Ctrl+F5) when you’ve made sweeping changes across multiple objects and want to ensure everything is fully synced.
RAD Is Ready for Production Use
Erik mentions that he overheard someone at Microsoft expressing frustration that developers weren’t using RAD publishing. In its early days, RAD wasn’t very reliable, and many developers learned to avoid it. But it has matured significantly — it’s now actually very good and reliable. If you dismissed it in the past, it’s worth giving it another try.
It’s All About the Inner Loop
For developers, the “inner loop” is the cycle from typing code to executing it, debugging it, and correcting it. Every second you can shave off that loop is a win. RAD publishing can cut deployment times from minutes down to seconds, which adds up enormously over a day of development work.
Summary
The rad.json file in your AL project enables Rapid Application Development publishing. By using Alt+F5 instead of the standard publish shortcuts, you deploy only the changed objects to your server — dramatically reducing deployment time. It’s especially valuable for large projects, but even on moderately sized apps, shaving seconds off every deployment makes for a much smoother development experience. Give it a try on your next project and see the difference for yourself.
