[plug-in] Harden and polish the Plug-in System

[ashumilova]

The first implementation phase of Plug-in system has been finished, and it included all the essential APIs needed for the start to interact with Theia components from plug-ins.

Just to revise, they are the following: Preferences, Commands, Notifications, Editor, Status bar, Terminal, Open/Save/Input Dialogs and Output channel APIs. Also new namespace - environment was introduced.

The next step is to make our Plug-ins API model tougher and more clearly defined and used.

It could be divided in following sections, which could also be split in separate epics.

Fill-in the missing pieces:

There the APIs, that are still missing, and the list could really increase during work being in progress. (Note: the order is not prioritized)

• [x] Workspace Folder Pick API https://github.com/theia-ide/theia/issues/2337
• [x] Tree + Tree view + Tree data provider https://github.com/theia-ide/theia/issues/2782
• [x] File system watcher creator (needed for LS)
• [x] Find files
• [x] Apply edit (workspace) (needed for LS) https://github.com/theia-ide/theia/issues/2784
• [ ] Configuration and Defaults contribution
• [x] Languages https://github.com/eclipse/che/issues/10206 https://github.com/theia-ide/theia/issues/2341
• [ ] Debugger API (bigger)
• [x] Extensions API https://github.com/theia-ide/theia/issues/2561
• [x] WebView API

Low priority:

• [x] syntax highlight APIs
• [ ] Register task provider
• [x] Register file system provider https://github.com/theia-ide/theia/issues/2861
• [ ] Version control system management APIs

Nice to have

• [ ] Themes management
• [ ] Snippets
• [x] Menu Plugin API https://github.com/theia-ide/theia/issues/2785
• [x] Register text document content provider https://github.com/theia-ide/theia/issues/2786
• [x] Key bindings https://github.com/theia-ide/theia/issues/2783
• [x] API endpoint for window.showTextDocument theia-ide/theia#2801
• [x] API endpoint window.withProgress theia-ide/theia#2802

Plug-in Model documentation

• [ ] Provide the detailed documentation on all the existing APIs
• [ ] Provide the tutorial for plugin writers

Move existing extensions to plugin model

• [x] SSH extension
• [x] GitHub extension

[AlexTugarev]

can this be considered too? https://github.com/theia-ide/theia/issues/2258

[ashumilova]

@AlexTugarev yes, sure

[vince-fugnitto]

I believe this issue is now outdated, and we can safely close. We have other "epics" which describe improvements to the plugin-system and vscode support.