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120 lines
5.8 KiB
HTML
120 lines
5.8 KiB
HTML
<!DOCTYPE html>
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>Handbook Troggle Architecture Speculations</title>
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<link rel="stylesheet" type="text/css" href="../../css/main2.css" />
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</head>
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<body><style>body { background: #fff url(/images/style/bg-system.png) repeat-x 0 0 }</style>
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<h2 id="tophead">CUCC Expedition Handbook</h2>
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<h1>Troggle Architecture Speculations</h1>
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<pre>
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From: Philip Sargent (Gmail) [mailto:philip.sargent@gmail.com]
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Sent: 19 April 2020 01:28
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To: expo-tech@lists.wookware.org
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Subject: vague thoughts about future troggle architecture
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</pre>
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<p>
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At our last virtual pub Sam confirmed that using today's tools to
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re-partition troggle with all the user interface in the user's browser would
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be utterly horrible using current tools (javascript frameworks: react,
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angular etc.).
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<p>
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These frameworks get out of date in couple of years or so. So they don't
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give us the decade-long stability we need to match available maintenance
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effort.
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<p>
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A web API to expose the troggle database (read-only) would allow some keen
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person to write a special-purpose app on a phone, e.g. an entrance-locator
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app, talking directly to the database. But replacing the whole user
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interface does not seem feasible yet.
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<p>
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It did occur to me that we are missing a trick: 99+% of the database doesn't
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change except for survey data updates which, apart from during expo, happen
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only every week or so. And the database is only 10 MB so is entirely
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feasible to copy absolutely everything into the browser except for scanned
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images and photos.
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<p>
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So we could partition troggle so that all the user display bits run in the
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browser (or a progressive web app) using a python interpreter running in
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javascript. [yeah, expofiles would need some subset labelled as needing to
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be forcibly downloaded, but the rest coming only on demand.] Some django
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enthusiast must have done this already surely ? Ah yes, Brython.<br>
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<a href="https://github.com/brython-dev/brython">github.com/brython-dev/brython</a><br>
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<a href="https://www.brython.info/">www.brython.info</a>
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<p>
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Which is fun, but not useful. And not just because it is immature. None of
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this addresses <strong>our biggest problem: devising something that can be
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maintained by fewer, less-expert people who can only devote short snippets
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of time and not long-duration immersion</strong>.
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<h3>Our biggest problem</h3>
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We need:
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<ul>
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<li>something that can be maintained by fewer, less-expert people
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<li>who can only devote short snippets of time
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<li>without requiring weeks of long-duration deep immersion
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</ul>
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<h3>Federation of independent scripts</h3>
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<p>
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I know Wookey has been thinking of a loose federation of independent scripts
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working on the same data, but the more I look at troggle and the tasks it
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does the less I feel that would work. <strong>At the core there is a common data
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model that everything must understand</strong> - and the only unambiguous way of
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presenting that data model is working code, e.g. see
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<a href="http://expo.survex.com/handbook/troggle/trogarch.html">Troggle architecture</a> and click on the image
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to see a bigger copy. [It is out of date - if someone can quickly generate
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an update that would be nice. It's on my <a href="../computing/todo.html">to-do list..</a>] Much of what
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wallets.py does (originally by Martin Green) is in troggle already - but
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better. [There is a many:many relationship between svx files and wallet
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directories in reality, not 1:1]
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<p>
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<h3>troggle now</h3>
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Troggle is very nearly fully working (not with as many functions as
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originally envisaged admittedly) but very nearly.
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The QM data display needs writing; but other than that it's in pretty good
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shape. [Ah, yes, we should really add "drawings" as a core concept as well
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as "surveyscans". That will be a bit of work.]
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<p>
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<h3>Need for separate data-import checking scripts</h3>
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The one thing external scripts would be really useful for is syntax checking
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and reference checking prior to import. I have found some weird and
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wonderful filename paths inside the tunnel and therion drawings, and in
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survex *ref paths.
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<h3>Non-django troggle</h3>
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<p>Another possibility is ripping django out of troggle and leaving bare python
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plus a SQL database. This means that programmers would need to understand more SQL
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but would not need to understand "django". Arguably this
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could mean that we could gain.
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<p>Writing our own multi-user code would not be sensible, hence the database.
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But we could move to a read-only system where the only writing happens on data-import.
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Then we could use python 'pickle()' or 'json()' read-only data structures, but we
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would need to create all our own indexing and cross-referencing code.
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<p>There would be more lower-level code, but the
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different segments of the system could be in caving-sensible modules not
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django-meaningful modules. And we would not have all the extra
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language-like constructs that django introduces e.g. <var>X.objects.set_all()</var>, which
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modern editors complain about because it is a django idiom and
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not a function within the python codebase.
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(We could retain an HTML templating engine though.)
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<h3><em>Addendum</em></h3>
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<p>There is a templating engine <a href="https://mozilla.github.io/nunjucks/">Nunjucks</a>
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which is a port to JavaScript of the Django templating system we use
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(via <a href="https://palletsprojects.com/p/jinja/">Jinja</a> - these are the same people who do Flask). This would be an obvious thing to use if we needed to go in that direction.
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<p>Several organisations have moved their user-interface layer to the browser using
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Nunjucks including <a href="https://service-manual.nhs.uk/design-system/prototyping">
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the NHS digital service</a> and Firefox.
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<hr />
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Go on to: <a href="trogarch.html">Troggle architecture</a><br />
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Return to: <a href="trogintro.html">Troggle intro</a><br />
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<hr />
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</body>
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</html>
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