CEP Guide Part 1: Technical overview

This is part of the CEP Mega Guide series. See also: sample CEP extension source

CEP 5 Overview

The CC 2014 release in June 2014 saw a major update to CEP (Common Extensibility Platform), the extension framework inside many Adobe tools. What’s most interesting, though, is that CEP 5 is built entirely on web technology - the UI layer is buit with standard HTML5, all logic is written in Javascript, and Node.js (with its enormous ecosystem of libraries) is available behind the scenes. With CEP 5, it’s now extremely straightforward for a web developer to customize Adobe tools, or hook them up to other services or platforms.

Use Cases

There’s a huge value to having the ability to customize the tools one uses professionally. Obviously you can use CEP 5 any way you like, but personally I picture three main use cases:

  • To make yourself (or your company) more productive - by automating whatever is relevant to your unique workflow. For example, if you use Photoshop to edit textures for a game, a custom panel that knows how to package assets and launch a new local build might save a lot of time. (Especially on a big project where dozens of designers might use it..)
  • Integrating Creative Cloud tools to services or technologies beyond what Adobe has thought of. This could be as simple as posting to Twitter from Illustrator, or as complicated as controlling Photoshop with voice commands or LeapMotion (which works, by the way @_@ ).
  • Building your own authoring story. If your work involves any ad-hoc file formats or structured data that’s hard to create visually, a CEP extension might be enough to turn Photoshop or Flash into your own custom authoring tool.

Here follows a brief look at the technology stack behind CEP 5 - each topic will be covered in depth in the rest of the series.

There are currently eight supported tools: Photoshop, Illustrator, Flash Pro, Premiere Pro, After Effects, Prelude, InDesign, and InCopy. In all cases, HTML panel support was added in the most recent major version (the CC 2014 release from June 2014).

The moving parts inside a CEP 5 extension are straightforward:

  • A manifest.xml  which declares the extension’s title, version, supported tools, etc.
  • HTML content (to be the extension’s UI)
  • Node.js modules (such as you’d get from npm)
  • Scripts to be executed by the host tool
  • Other assets (panel icons, UI assets, or whatever other files the extension might use)

In the minimal case, you can get by with just manifest.xml and index.html.

To render an extension’s HTML, each panel uses an embedded instance of Chromium (i.e. CEF), so the UI layer is basically no different from your desktop browser - even very modern HTML features work as you’d expect. Likewise, each tool supporting CEP 5 has a built-in Node.js implementation, so extensions can use Node even if it’s not installed on the user’s machine (or the developer’s, for that matter).

For tool integration, each of the Adobe tools contains a Javascript virtual machine that can see the tool’s internal DOM and APIs. For Flash this is JSFL, and for all other tools it’s ExtendScript. Finally, since the UI uses Chromium, debugging extensions is easy - it’s done through an inspector that’s exactly like the developer tools in each major browser.


Customizing tools like Photoshop and Flash with nothing but web technology might sound surprising, but in practice it’s quite accessible for any web developer, and well worth the effort if you use Adobe tools (or your company does).

Next up is Part 2: Getting Started, which covers minimal source code and the steps required to run an extension.