# Writing content for RELATE¶

## Git repository¶

In RELATE, one course corresponds to one Git repository.

Data for a course in RELATE is contained in a git repository. RELATE understands the structure of a repository and makes use of the version history present. For example, you could be previewing and testing some newly developed course content, while the students continue to work with a prior version until you make the new version explicitly available.

One revision (“commit”) of the git repository is always viewed as the “current” one. This is the one being shown to all visitors. In addition, each user (with sufficient privileges) may be previewing a different version of their choosing.

Note

When editing RELATE git repositories on Windows, make sure that the core.autocrlf option is set appropriately (namely, so that line endings are represented in the ‘UNIX’ convention, as a single newline character).

RELATE maintains a git repository for each course and can fetch from one external git repository configured in the course page and update its internal git repository from this external git repository. A user with sufficient privileges can access this internal git repository by using git pull and git push with the HTTPS URL given on the “Update Course Content” page, RELATE username as the username and RELATE authentication token as the password.

## YAML¶

Most of the files in the Git repository defining course content are written in YAML. YAML is a structured plain text format. If you know what XML is: The conceptual idea is a little like XML, but YAML is much easier to read and write by humans than XML.

Here’s an example:

title: "Homework 3"
description: |

# Homework 3

Welcome to our third homework set, where you will learn about principal component analysis,
applications of linear least squares, and more.

rules:
start:
-
if_before: end_week 1
if_has_role: [student, ta, instructor]
if_has_fewer_sessions_than: 2
may_start_new_session: True
may_list_existing_sessions: True

-
may_start_new_session: False
may_list_existing_sessions: True

access:
-
if_before: end_week 2
permissions: [view, modify, see_correctness]
message: "Welcome! This message is brought to you by the access rules."

-

-
if_completed_before: end_week 1
credit_percent: 100

-
if_completed_before: end_week 2
credit_percent: 50

-
credit_percent: 0
...


### Macros in YAML¶

Repetitive text in YAML (such as for example Flow rules that are repeated for each instance of a given type of assignment, with very minor modifications) can be abbreviated through the use of the Jinja templating language. Jinja expansion takes place everywhere in YAML code except for block literals:

# Jinja usable here

correct_code: |

# No Jinja here


RELATE markup does its own Jinja expansion though, so such block literals can use Jinja.

## On system lock-in¶

One key feature of RELATE is that the content you write for it is versatile and easy to repurpose. To start, everything you write for RELATE is just a readable, plain text file, so there are no retrieval or interpretation issues.

Next, the pandoc tool can be used to export RELATE markup to essentially any other markup format under the sun, including LaTeX, HTML, MediaWiki, Microsoft Word, and many more.

Further, YAML files are quite easy to read and traverse in most programming languages, facilitating automated coversion. This example Python script provided as part of RELATE takes a flow and converts it to a paper-based worksheet. To do so, it makes use of pypandoc and PyYAML.

## Validation¶

While YAML lets you define arbitrary structures, RELATE imposes a number of rules on what your YAML documents should look like to be acceptable as course content.

These rules are automatically checked as part of setting a new revision of the Git repository to be the active or previewed revision.

This helps avoid mistakes and ensures that the students always see a working site.

See Installing the Command Line Interface for how to use validation from the command line while developing content.

## RELATE markup¶

All bulk text in RELATE is written in Markdown, with a few extensions. Here are a few resources on Markdown:

To allow easy experimentation with markup, RELATE has a “markup sandbox” in the “Content” menu where the rendered form of any RELATE markup can be previewed.

In addition to standard Markdown, the following extensions are supported:

### Tables¶

Using the following syntax:

First Header  | Second Header
------------- | -------------
Content Cell  | Content Cell
Content Cell  | Content Cell


### Markdown nested in HTML¶

Using the following syntax:

<div markdown="1">
This is a *Markdown* Paragraph.
</div>


### “Fenced” code blocks¶

Using the following syntax:

python
def f(x):
return 5+x



### Custom URLs¶

A few custom URL schemas are provided to facilitate easy linking around a RELATE site:

• The URL schema course:course-name links to another course on the same RELATE instance. A URL course: may be used to link to the current course.

• The URL schema flow:flow-name provides a link to the start page of a flow.

In Markdown, this might look like this:

Please take [today's quiz](flow:quiz-lecture-17).


This resolves to a link to the flow contained in flows/quiz-lecture-17.yml.

• The URL schema calendar: links to the course calendar page.

• The URL schema staticpage:some/where links to the page found in staticpages/some/where.yml in the repository. (Note the added staticpages.)

• The URL schema repo:some/file/name.png will be resolved to the file some/file/name.png in the course’s Git repository.

In Markdown, this might look like this:

![A bouncing ball](repo:images/bouncing-ball.gif)


To avoid exposing sensitive files, a special file .attributes.yml must be present in the same directory as the file which allows public access to the file. This file should be valid YAML and look like this:

unenrolled:
- "*.png"
- "*.jpeg"


In addition to unenrolled, the file can also include the following sections:

• unenrolled: Allow access to these files from anywhere on the Internet, except for locked-down exam sessions.

• in_exam: Allow access to these files when a locked-down exam is ongoing.

• student: Allow access to these files for student, ta, and instructor roles

• ta: Allow access to these files for ta and instructor roles

• instructor: Allow access to these files only for the instructor role

• The URL schema repocur:some/file/name.png generally works the same way as repo:, with these differences:

• Unlike repo:, the links generated by this URL schema will not contain the current repository version. That means the link can safely be bookmarked by a user and will always deliver the current version of that file.

• The generated links are also easier to create by hand and thus more useful for linking from outside of RELATE.

• Links generated by repocur: cannot be cached as effectively as those generated by repo:, and they take a few more database lookups to resolve. Using repocur: therefore consumes more bandwidth and computation on the RELATE server. As a result, it is advantageous to use repo: whenever practical.

Note

A URL schema media: used to exist and will continue to be supported. Its use is discouraged in favor of repo: and repocur:.

Warning

For the continued support of the media: URL schema, the entire media/ subdirectory of the git repository is unconditionally accessible from anywhere in the world, by anyone. Sensitive files should not be stored there.

### LaTeX-based mathematics¶

Use $...$ to enclose inline math and $$...$$ to enclose display math. This feature is provided by MathJax.

If you would like to use AMSMath-style LaTeX environments, wrap them in $$...$$:

\begin{align*} ... \end{align*}


### Symbols and Icons¶

RELATE includes FontAwesome, a comprehensive symbol set by Dave Gandy. Symbols from that set can be included as follows:

<i class="fa fa-heart"></i>


### In-line HTML¶

In addition to Markdown, HTML can also be allowed and puts the full power of modern web technologies at the content author’s disposal. In order to use arbitrary HTML, the course must have the setting “may present arbitrary HTML to participants” enabled. This setting is available in the admin functionality.

When enabled, Markdown and HTML may also be mixed. For example, the following creates a box with a recessed appearance around the content:

<div class="well" markdown="1">
Exam 2 takes place **next week**. Make sure to [prepare early](flow:exam2-prep).
</div>


The attribute markdown="1" instructs RELATE to continue looking for Markdown formatting inside the HTML element.

### Video¶

RELATE includes VideoJS which lets you easily include HTML5 video in your course content. The following snippet shows an interactive video viewer:

<video id="myvideo" class="video-js vjs-default-skin"
poster="/video/cs357-f14/encoded/myvideo.jpeg"
data-setup='{"playbackRates": [1, 1.3, 1.6, 2, 4]}'>
<source src="/video/cs357-f14/encoded/myvideo.webm" type='video/webm' />
<source src="/video/cs357-f14/encoded/myvideo.mp4" type='video/mp4' />
<p class="vjs-no-js">To view this video please enable JavaScript, and consider upgrading to a web browser that <a href="http://videojs.com/html5-video-support/" target="_blank">supports HTML5 video</a></p>
</video>


### Ipython notebook to HTML¶

RELATE provides the functionality of rendering Ipython Notebooks in course pages, by using nbconvert.

render_notebook_cells(ipynb_path, indices=None, clear_output=False,
clear_markdown=False)
Parameters
• ipynb_pathstr, the path of the ipython notebook in the repo.

• indiceslist, the indices of cells which are expected to be rendered. For example, [1, 2, 3, 6] or range(3, -1). If not specified, all cells will be rendered.

• clear_outputbool, indicating whether existing execution output of code cells should be removed. Default: False.

• clear_markdownbool, indicating whether all text cells will be removed. Default: False.

Return type

str, rendered markdown which will be consequently converted to HTML.

For example, the following snippet shows the HTML version of test.ipynb in repo folder code, with markdown (text_cells) and output (execution result of code_cells) removed:

{{ render_notebook_cells("code/test.ipynb", clear_markdown=True, clear_output=True) }}


### Macros¶

Repetitive text (such as the fairly long video inclusion snippet above) can be abbreviated through the use of the Jinja templating language. For example, you could have a file macros.jinja in the root of your Git repository containing the following text:

{% macro youtube(id) -%}
<iframe width="420" height="315" src="//www.youtube.com/embed/{{id}}" frameborder="0" allowfullscreen>
</iframe>
{%- endmacro %}


This could then be used from wherever RELATE markup is allowed:

Some text... More text...

{% from "macros.jinja" import youtube %}

Some text... More text...


## The Main Course Page File¶

One required part of each course repository is a YAML file that is typically named course.yml Other names may be specified, enabling multiple courses to be run from the same repository. It has the same format as a course page, described next, and it contains the information shown on the main course page.

## “Static” (i.e. non-interactive) pages¶

A static page looks as follows and is either the main course file or a file in the staticpages subfolder of the course repository.

class Page
content

RELATE markup. If given, this contains the entirety of the page’s content. May only specify exactly one of content or chunks.

chunks

A list of Course Page Chunks. Chunks allow dynamic reordering and hiding of course information based on time and rules.

May only specify exactly one of content or chunks.

### Course Page Chunks¶

A ‘chunk’ of the course page is a piece of RELATE markup that can shown, hidden, and ordered based on a few conditions.

Here’s an example:

chunks:

-
title: "Welcome to the course"
id: welcome
rules:
-   if_before: end_week 3
weight: 100

-   weight: 0

content: |

# Welcome to the course!


class CourseChunk
title

A plain text description of the chunk to be used in a table of contents. A string. No markup allowed. Optional. If not supplied, the first ten lines of the page body are searched for a Markdown heading (# My title) and this heading is used as a title.

id

An identifer used as page anchors and for tracking. Not user-visible otherwise.

rules

A list of CoursePageChunkRules that will be tried in order. The first rule whose conditions match determines whether the chunk will be shown and how where on the page it will be. Optional. If not given, the chunk is shown and has a default CoursePageChunkRules.weight of 0.

content

The content of the chunk in RELATE markup.

class CoursePageChunkRules
weight

(Required) An integer indicating how far up the page the block will be shown. Blocks with identical weight retain the order in which they are given in the course information file.

if_after

(Optional) A datespec that determines a date/time after which this rule applies.

if_before

(Optional) A datespec that determines a date/time before which this rule applies.

if_has_role

(Optional) A list of a subset of the roles defined in the course, by default unenrolled, ta, student, instructor.

if_has_participation_tags_any

(Optional) A list of participation tags. Rule applies when the participation has at least one tag in this list.

if_has_participation_tags_all

(Optional) A list of participation tags. Rule applies if only the participation’s tags include all items in this list.

if_in_facility

(Optional) Name of a facility known to the RELATE web page. This rule allows (for example) showing chunks based on whether a user is physically located in a computer-based testing center (which RELATE can recognize based on IP ranges).

shown

(Optional) A boolean (true or false) indicating whether the chunk should be shown.

## Calendar and Events¶

The word event in relate is a point in time that has a symbolic name. Events are created and updated from the ‘Content’ menu.

Events serve two purposes:

• Their symbolic names can be used wherever a date and time would be required otherwise. For example, instead of writing 2014-10-13 10:30:00, you could write lecture 13. This allows course content to be written in a way that is reusable–only the mapping from (e.g.) lecture 13 to the real date needs to be provided–the course material istelf can remain unchanged.

• They are (optionally) shown in the class calendar.

For example, to create contiguously numbered lecture events for a lecture occuring on a Tuesday/Thursday schedule, perform the following sequence of steps:

• Create a recurring, weekly event for the Tuesday lectures, with a starting ordinal of 1. (“Create recurring events” in the “Instructor” menu.)

• Create a recurring, weekly event for the Thursday lectures, with a starting ordinal of 100, to avoid clashing with the previously assigned ordinals. (“Create recurring events” in the “Instructor” menu.)

• Renumber the events with the relevant symbolic name. (“Renumber events” in the “Instructor” menu.) This assigns new ordinals to all events with the specified symbolic name by increasing order in time.

### Specifying dates in RELATE¶

In various places around its YAML documents, RELATE allows dates to be specified. The following formats are supported:

• symbolic_name ordinal (e.g. lecture 13) to refer to the start time of calendar events with an ordinal.

• symbolic_name (e.g. final_exam) to refer to the start time of calendear events without an ordinal.

• end:symbolic_name ordinal (e.g. end:lecture 13) to refer to the end time of calendar events with an ordinal.

• end:symbolic_name (e.g. end:final_exam) to refer to the end time of calendar events without an ordinal.

• ISO-formatted dates (2014-10-13)

• ISO-formatted times (2014-10-13 14:13)

Each date may be modified by adding further modifiers:

• +/- N (weeks|days|hours|minutes) (e.g. hw_due 3 + 1 week)

• @ 23:59 (e.g. hw_due 3 @ 23:59) to adjust the time of the event to a given time-of-day.

Multiple of these modifiers may occur. They are applied from left to right.

### The Calendar Information File: events.yml¶

The calendar information file, by default named events.yml, augments the calendar data in the database with descriptions and other meta-information. It has the following format:

event_kinds:
lecture:
title: Lecture {nr}
color: blue

exam:
title: Exam {nr}
color: red

events:
"lecture 1":
title: "Alternative title for lecture 1"
color: red
description: |
*Pre-lecture material:* [Linear algebra pre-quiz](flow:prequiz-linear-algebra) (not for credit)

* What is Scientific Computing?
* Python intro


The first section, event_kinds, provides color and titling information that applies to all events sharing a symbolic name. The string {nr} is automatically replaced by the ‘ordinal’ of each event.

The secondsection, events, can be used to provide a more verbose description for each event that appears below the main calendar. Titles and colors can also be overriden for each event specifically.

All attributes in each section (as well as the entire calendar information file) are optional.