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https://github.com/rsc/tiddly

TiddlyWiki (actually TiddlyWeb) server for Google App Engine
https://github.com/rsc/tiddly

Last synced: 18 days ago
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TiddlyWiki (actually TiddlyWeb) server for Google App Engine

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README 

        
# TiddlyWiki App Engine Server



This is a minimal Google App Engine app, written in Go, that can serve

as the back end for a personal [TiddlyWiki](http://tiddlywiki.com/)



The [TiddlyWiki5](https://github.com/Jermolene/TiddlyWiki5) implementation

has a number of back end options. This app implements the backend expected

by the “[TiddlyWeb](http://tiddlyweb.com/) and TiddlySpace components” plugin.



The usual way to deploy TiddlyWeb is to run a fairly complex Python web server

program. I'd rather not. Instead I implemented a minimal Go server that responds

appropriately to the (relatively few) needed JSON API calls.



## Authentication



The TiddlyWeb JSON API envisions a multiuser system in which different users have

access to different sets of tiddlers. This Go server contains none of that:

it assumes that all users have full access to everything, although it does record

who created which tiddlers. The only access control is that the app.yaml here

requires HTTPS and administrator login for all URLs, and as a “belt and suspenders” measure,

the app itself also refuses to serve to non-admins, as checked by user.IsAdmin.



See the "Re Authentication" comment in tiddly.go for information about

making the server publicly read-only (it's not quite perfect).



## Data model



The app stores the current tiddlers in Cloud Datastore as Tiddler entities.

It also stores every version of every tiddler as TiddlerHistory entities.

Currently nothing reads the TiddlerHistory, but in case of a mistake that

wipes out important Tiddler contents it should be possible to reconstruct

lost data from the TiddlerHistory.



The TiddlyWiki downloaded as index.html that runs in the browser

downloads (through the JSON API) a master list of all tiddlers and their

metadata when the page first loads and then lazily fetches individual 

tiddler content on demand.



## Deployment



Create an Google App Engine standard app and deploy with



	appcfg.py -A your-app -V your-version update .



Then visit https://your-app.appspot.com/. As noted above, only admins

will have access to the content.



## Plugins



TiddlyWiki supports extension through plugins. 

Plugins need to be in the downloaded index.html, not lazily

like other tiddlers. Therefore, installing a plugin means 

updating a local copy of index.html and redeploying it to

the server.



## Macros



TiddlyWiki allows tiddlers with the tag `$:/tags/Macro` to contain

global macro definitions made available to all tiddlers.

The lazy loading of tiddler bodies interferes with this: something

has to load the tiddler body before the macros it contains take effect.

To work around this, the app includes the body of all macro tiddlers

in the initial tiddler list (which otherwise does not contain bodies).

This is sufficient to make macros take effect on reload.



For some reason, no such special hack is needed for `$:/tags/Stylesheet` tiddlers.



## Synchronization



If you set Control Panel > Info > Basics > Default tiddlers by clicking

“retain story ordering”, then the story list (the list of tiddlers shown on the page)

is written to the server as it changes and is polled back from the server every 60 seconds.

This means that if you have the web site open in two different browsers 

(for example, at home and at work), changes to what you're viewing in one

propagate to the other.



## TiddlyWiki base image



The TiddlyWiki code is stored in and served from index.html, which

(as you can see by clicking on the Tools tab) is TiddlyWiki version 5.1.21.



Plugins must be pre-baked into the TiddlyWiki file, not stored on the server

as lazily loaded Tiddlers. The index.html in this directory is 5.1.21 with

the TiddlyWeb and Markdown plugins added. The TiddlyWeb plugin is

required, so that index.html talks back to the server for content.



The process for preparing a new index.html is:



- Open tiddlywiki-5.1.21.html in your web browser.

- Click the control panel (gear) icon.

- Click the Plugins tab.

- Click "Get more plugins".

- Click "Open plugin library".

- Type "tiddlyweb" into the search box. The "TiddlyWeb and TiddlySpace components" should appear.

- Click Install. A bar at the top of the page should say "Please save and reload for the changes to take effect."

- Click the icon next to save, and an updated file will be downloaded.

- Open the downloaded file in the web browser.

- Repeat, adding any more plugins.

- Copy the final download to index.html.