WEBVTT

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Hi everyone! I'm Mehmet Tekman,

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and I'm here to talk to you

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about using Amazon Kindles

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as a productivity dashboard for

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your various projects.

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In a nutshell, you describe your machines,

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your commands, and your schedules

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in an Org-Mode file,

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and then you just initialize

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your Kindle devices.

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These devices are asleep

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most of the time,

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but they wake up at scheduled times

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to retrieve content

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from the centralized server.

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Content can be Org mode and Emacs-based,

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or it can be from Web content,

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or it can just be static images and WAV.

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If you, like me, struggle to

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keep your life under tabs,

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or find it very hard to separate

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your work life from your home life,

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then you, like me, likely need

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some kind of passive background service

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that reminds you of where you are

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and what you are supposed to be doing.

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Even if it's just a sign saying,

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"You're at home! Relax!"

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An Amazon Kindle is perfect for this.

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In a nutshell, it's a cheap

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black and white e-ink device

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that can go for weeks

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without needing a single charge.

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Every year, Amazon brings out

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an incrementally better model,

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which makes the old devices obsolete,

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and you can find these older models

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for 5 euros on second-hand websites.

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Plus it runs Linux, has WiFi networking,

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and has a dedicated forum of hackers

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for getting the most out of the device.

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Some drawbacks of this is that

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the device often comes with unwanted bloat:

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over-the-air updates,

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it phones home to Amazon regularly,

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it has a secret microphone

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embedded in the device,

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and it has a bunch of creepy

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seemingly interdependent

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background processes,

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where killing one kind of kills the others

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risking that you will break the device.

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But this is where the community

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really shines through,

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since the friendly (and not-so-friendly)

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users (and developers)

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from the MobileRead forums have pretty much

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scraped out a good portion of the

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harmful Amazon scripts from the device.

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Some of the devices even use

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Awesome Window Manager,

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meaning you can really play around

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with the existing system

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without having to create

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your own X11 server.

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This then empowers users

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to display whatever they want on the device.

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One project that really got this going

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was the Kindle-Dash dashboard from

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Pascal Widdershoven, who really refined a

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lot of the internal scripts

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to stabilize the device.

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However, the project then

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puts the onus on the device

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to retrieve the data from

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somewhere else over the internet,

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and so you still need to 

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generate the content

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and place it on the web somewhere.

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Plus you need to do this and manage it

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for every Kindle device that you have.

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Kindle-Sync, however,

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is an entirely different beast,

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albeit one that builds off of the works

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of the aforementioned projects.

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It assumes that instead of just having

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one Kindle device around

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that you wish to re-purpose

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for productivity purposes,

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that you actually have

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multiple Kindle devices

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that you want to manage

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and configure in tandem.

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Everything is managed

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from a dedicated server (or a raspberry pi)

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which distributes jobs to multiple Kindles,

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running on different update timers.

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These timers are all managed

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from the server,

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and all the Kindle device has to do is:

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to wake up, power on the WiFi,

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receive some media, display the media, and

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receive a barebones RTC sleep request.

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Then it sleeps for the requested time,

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consuming no power, whilst displaying the

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desired media. That is maybe 10 seconds

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of awake time between each request.

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Cron does not actually run

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on the Kindle device itself,

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simply because it does not reliably work.

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All of this is handled by the server.

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With the server-client model,

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it also tries to restrict Amazon access.

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SSH keys are shared

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only from the client to the server,

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but not from the server to the client,

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so the Kindle cannot connect

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to the Raspberry Pi without a password.

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IPtables rules are also set

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so that the Kindle cannot phone home

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to Amazon, and the connections

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are restricted to just the LAN.

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So I got very curious at one point

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and decided to see how long

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a Kindle could last on a single charge

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in such an arrangement,

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so that every 15 minutes for 18 hours,

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I tested the device

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by sending a media item

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and recording the battery level.

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The Kindle doesn't seem to

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report the battery level

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very continuously,

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but at discrete percentages,

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so that you could end up with

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a graph that looks like this.

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Assuming you have half the charge,

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and use it once every hour -

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it will drop by 10% battery in 76 hours,

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which is roughly three days.

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It's hard to extrapolate

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with only three good summarized data points,

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of which the number of requests

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per battery level appear to diminish

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as shown in the table below,

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but the final result yields 76 requests

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with an average loss of 0.5% battery life

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per request. Which is not bad!

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Assuming you do a request every 2 hours

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from 8am to 8pm,

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and let it sleep at night,

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then that's approximately 6 requests a day,

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which could easily last a device

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for a month.

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The ksync script does

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essentially everything:

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from generating and fetching the media,

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to initializing all Kindle devices,

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generating the server cronjobs,

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log report summaries,

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editing the config tables,

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and much more.

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The media operations are comparatively

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much more complex

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and encompass a few media use cases

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such as fetching the weather

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(though only from Open Weather Maps)

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and retrieving Google Calendar views

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by week, month, agenda, and four day view.

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You can retrieve Org-Mode data

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from an Emacs instance on the server,

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which in my case

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I produce views for an agenda

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or a sparse tree of my main projects file.

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Finally we have gallery and wavfile,

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which are static resources

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which will never change once generated.

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The idea is that you feed it

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text and an image location,

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and it generates

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a Kindle-compatible image

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using imagemagick as a backend for it.

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In the case of the wavfile,

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it uses espeak on the backend.

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The below is summarized

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from the help-me text

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in the main ksync file,

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but essentially, you need to

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define your config in the CSV files,

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which we talk about in the next section;

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initialize all your Kindle devices,

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i.e. copy over SSH keys,

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kill all the unnecessary services,

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and prime them for media collection;

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and ensure that you have

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all your static media generated

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and fetchable; and finally

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you then refresh the scheduling

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on the server.

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Okay, so this is all good and well,

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and we now know what the server does

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and how to probe and inspect it -

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but how does the server generate

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much of the content?

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So a lot of the content

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will be dynamically generated,

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meaning it cannot be cached

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and is likely to change from hour to hour.

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The media content that is generated here

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are mostly PNG images

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and have a timestamp

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embedded in their filenames.

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The Emacs-specific content

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consists of a few views,

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namely the org-gcal views,

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org-agenda, and org-calories --

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essentially anything that Emacs can display

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and that you want to capture into an image.

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Emacs can't (as far as I know)

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render graphics in a headless way,

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so what we do instead

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is run Emacs in a dummy minimal X11 session

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via "xvrb-run."

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From inside, you can take screenshots

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as you would in 

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a normal desktop environment,

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but with the benefit that

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you don't actually need to invoke a desktop

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or interfere with an existing one.

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The minimal elisp shown here

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is all that is required

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to output your desired image from Emacs

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and configure it for the Kindle environment.

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On the web side of things,

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we don't really need to invoke

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a dummy X11 session

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because Chromium can run headless

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and can be controlled

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by the node library "puppeteer"

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to render dynamic content,

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focus on regions of the webpage,

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and take snapshots.

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The static content comprises

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of two types: images and audio.

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The content is accessed by a key,

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in this case Batman,

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and the content information

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is given by the "--extra" parameter

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which describes either or both

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an image and text.

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Okay, so now we have content,

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how do we schedule this content

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to appear on our desired machines

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at desired times?

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Everything is run via cron.

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So previously we saw that

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we only needed the tables MACHINES.csv,

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COMMANDS.csv, and multiple TIME_*.csv tables

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for the shell script to work.

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But Org-Mode does this far easier,

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since you can just have everything

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in the same file,

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and with the helper minor-mode,

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manage everything

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from a single Org-Mode document.

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Here I have 4 kindles and their shortnames.

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Yes, I even have a Kindle

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hanging outside my door.

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I have 11 defined commands

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which represent the views I want to see,

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and there are 4 timetables I use,

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but you can have

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everything on one, if you like.

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Rows are machine names,

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and columns are corresponding hours

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at which they run.

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Trust me, it's easier to configure

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repeating tasks just by repeating them

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multiple times, because at least this way,

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it's human readable,

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and the script which converts these

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to a cronjob

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collapses the repeating tasks by itself.

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The ksync script can be called

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from within the config.org file

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using this convenient 

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use-package declaration.

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All that one needs to do

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is to configure the ENVIRONMENT_VARIABLES

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by setting them in this table

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where you set the repo name,

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the config directory,

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where the media shall go,

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and the server IP,

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although this can be

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automatically detected.

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The package allows you

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to export your tables

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by running C-c C-c on them,

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and allows you to update all the jobs

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related to each of your clients.

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You can also initialize clients

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using this package --

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for either all of them

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or individual clients --

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and the package comes with

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some convenience functions

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to do this automatically

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for all tables in the buffer.

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With this, I want to say a big thank you

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to Takaaki Ishikawa

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for his fantastic "org-tree-slide"

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presentation package.

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To Pascal Widdershoven

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and David Hamp-Gonsalves,

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for their fantastic 

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kindle-dash repositories,

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for which some of my internal Kindle scripts

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are derived from.

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Also a big thanks to the friendly

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and not-so-friendly users and hackers

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in the MobileRead forums.

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And finally, a big thanks

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to the Emacs community

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and the conference organizers.

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Thank you! [captions by Mehmet]