forked from cory/tildefriends
Cory McWilliams
9248dfd97e
git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@4124 ed5197a5-7fde-0310-b194-c3ffbd925b24
65 lines
2.9 KiB
Markdown
65 lines
2.9 KiB
Markdown
# Tilde Friends Structure
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[Back to index](#index)
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Tilde Friends is a mostly-self-contained executable written in C.
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In combines the following key components:
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- A Secure Scuttlebutt (SSB) client/server. This talks with other SSB
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instances, storing messages and blobs for anyone visible to local
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users as they are encountered and sharing anything published locally
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as appropriate.
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- An sqlite database. This is where the SSB instance stores its data.
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The general schema involves a `messages` table, storing mostly JSON,
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a `blobs` table storing arbitrary blob data, and a `properties` table,
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storing arbitrary state gleaned from `messages` and `blobs`, generally
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updated on demand and incrementally.
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- A QuickJS runtime. The core process runs stock scripts and has access
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and permission to use all resources. All other processes, which
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includes everything which runs untrusted code created by Tilde Friends
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users, are strictly sandboxed in ways similar to how web browsers run
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untrusted code. All attempts to access potentially sensitive resources
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are mediated through the core process.
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When run with no arguments, it starts a web server on
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[http://localhost:12345/](http://localhost:12345/) and an SSB node.
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## Web Interface
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The Tilde Friends web server provides access to Tilde Friends applications,
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which are arbitrary user-defined web applications.
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At the top left, in addition to some basic navigation links, is an `edit`
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link. Anyone can view, modify, and run in-place the code to any Tilde
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Friends application by using the in-browser editor.
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At the top right, one can `login` (to save work in their own space)
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or `logout` (proceeding as a guest).
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The rest of the page is an iframe belonging to the application.
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## Special Paths
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- `/~user/app/` - Tilde Friends application paths take the form `/~user/app/`, where `user`
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is a username of a Tilde Friends account, and `app` is an arbitrary name
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of an application saved by the given user.
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- `/~user/app/file` - A raw file in an app.
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- `/&blobid.ed25519` - A raw blob. Content-Type is inferred for at least
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a few common image types.
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## Communication Channels
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Web Browser <-> Core <-> Sandbox
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Visiting an application path delivers stock HTML and JavaScript which
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establishes a WebSocket connection back to the server.
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At this point, a new sandbox process is started in Tilde Friends, much
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as a new sandboxed process might be started for a new tab in a web
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browser. This process has a custom RPC connection to the core process
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which holds the WebSocket connection to the browser.
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The custom RPC communication between the sandbox process and the core
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process facilitates passing and calling functions remotely. Calling a
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function in another process returns a `Promise`.
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An application will typically call `app.setDocument()` at startup to
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populate the app's iframe in the web browser with its own client web
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application resources. |