1. Plug-in Architectures Presented by Truc Nguyen

2. What’s a plug-in? “a type of program that tightly integrates with a larger application to add a special capability to it” - CNET “a set of software components that adds specific abilities to a larger software application” - Wikipedia

3. What’s a plug-in? Component architectures Semantics –Plug-ins –Extensions –Add-ons

4. Plug-ins Not hard-coded into host app –Unknown at compile time Not a standalone application One step further: compose an entire application out of plugins

5. Why do have plug-ins? Extensible Modular Customizable Keep It Small and Simple!

6. Traditional vs Pure

7. Traditional Plug-in Extend capabilities of base application Not compiled into the application

8. Pure Plug-in Everything is a plug-in Plug-ins extend other plug-ins Where does that leave the base application? –A run-time engine for plug-ins –Plug-ins become hosts to other plug-ins by providing extension points How do plug-ins play nicely with each other? –Abide by the framework’s or each other’s rules

9. Pure Plug-in Engine Keeping track of where the right plug-in code is and running it Maintain a registry of plug-ins and functions that go with each Manage extension model and dependencies between plug-ins

10. Plug-in Design Patterns Best practice solutions to solve a design problem How to support dynamic loading of modules unknown during compilation

11. Plug-in Pattern

12. Eclipse Well known as a Java IDE Pure plug-in architecture –Runtime engine itself is a bunch of core plug- ins except for tiny bootstrap code Universal plug-in architecture for creating “anything, but nothing in particular” Each plug-in has a manifest

13. Eclipse

14. Gecko (NPAPI) Netscape Plugin Application Programming Interface Plug-in is completely controlled by web page that calls it On start, Gecko looks for plug-in modules in a specified locations on the system On a page with certain embedded media, checks for plug-in with matching MIME type creates new instance and runs it

15. Photoshop Central Plug-in loader –Scans PiPL (Plug-in Property List) Fixed types –filter, import, export, file format, automation –selection and parser (not implemented by 3 rd party) Non-Photoshop applications can support Photoshop plug-ins

16. Chrome Scripting API vs Browser API Extensions can modify the DOM Can have access to the history, current tabs, bookmarks, etc Composed of files, can be packaged as.crx –manifest.json –HTML files –JavaScript –Other resources (e.g CSS, images)

17. Chrome Background pages –Persistent or event Content scripts are JS that executes in the context of the page just loaded –Can change the DOM on the current page –Can’t change the DOM on the background page of parent extension Callbacks execute on a user action

18. Challenges Installing and updating –Configuration plugin Security Concurrent plug-in version –Eclipse convention: Only plug-ins that contribute code libraries can coexist Scalability

19. Questions?