14. Run the Application from a Notebook

UNDER DEVELOPMENT

Jupiter.org: The Jupyter Notebook is an open-source web application that allows you to create and share documents that contain live code, equations, visualizations and narrative text. Uses include: data cleaning and transformation, numerical simulation, statistical modeling, data visualization, machine learning, and much more.

Julia supports Jupiter Notebooks. A notebook combined explaining text with code makes it ideal as a teaching tool. It also allows you to experiment with the code.

Assuming you created the containers testsshd and testsshd2 in chapter 13, we created two notebooks to test them.

ar.ipynb
website.ipynb

The notebooks are part of the GitHub project TestAppliAR. You need to add the package IJulia.jl to run the notebooks.

14. Run the Application from a Notebook

Activity 14.1: Using a Julia Notebook
Notebook commands
Exercise 14.1: Run a Website
Summary

Activity 14.1: Using a Julia Notebook

Prerequisites

A processor unit preferable of at least three cores.
Ubuntu 20.04.
Julia 1.5.
Git installed.
Docker installed.
The two docker containers testsshd and testsshd2 were created according to the course BAWJ, chapter 13.

In this activity, you will:

Add the IJulia package.
Prepare the containers.
Clone the GitHub project TestAppliAR.
Create the data files.

Step 1: Add the IJulia package

Step	Action	Comment
1	$ Add IJulia](../appendix/#Install-IJulia)	Follow the instruction in the link.

Step 2: Prepare the containers

You will add the Julia packages AppliSales, AppliGenralLedger, AppliAR, and Query to the containers.

Step	Action	Comment
1	$ docker start test_sshd	Start the container test_sshd.
2	$ ssh rob@172.17.0.2	Enter the container.
3	$ julia	Start Julia.
4	julia> ]	Activate the Package Manager.
5	pkg> add AppliSales, AppliGenralLedger, Query	Add the packages
6	pkg> add https://github.com/rbontekoe/AppliAR.jl	Add AppliAR.
7	pkg> instantiate	Download the dependencies.
8	pkg> Ctrl-D	Exit Julia.
9	$ Ctrl-D	exit the container.
10	$ docker start test_sshd2
11	$ ssh rob@172.17.0.3	Enter the container test_sshd2.
12	Repeat steps 3 untill 9

Step 3: Clone the GitHub project TestAppliAR

You will clone the project TestAppliAR from GitHub, download the dependencies, and precompile the Julia code.

Step	Action	Comment
1	$ mkdir testar	Create a folder `testar` where you can store the cloned project.
2	$ cd testar
3	$ git clone https://github.com/rbontekoe/TestAppliAR.git	Clone the project.
4	$ cd TestAppliAR	Enter the folder TestAppliAR.
5	julia> ]	Activate the Package Manager.
6	pkg> add IJulia	Add IJUlia.
7	pkg> activate .	Activate the current environment.
8	pkg> instantiate	Download dependecies.
9	pkg> precompile	Precompiling project...
10	pkg> <BackSpace>	Back to Julia.

Step 4: Create the data files

You will use the notebook ar.ipynb to create the data files.

In test_sshd:

test.txt
test.txt

In test_sshd2

test.txt
test.txt
invoice_nbr.txt

Step	Action	Comment
1	julia> using IJulia	Load IJulia.
2	julia> notebook(dir=".", detached=true)	Opens the start folder in the browser.
3	Double click on: ar.ipynb	Open the notebook.
4	Put the cursor in the first cell and press: Shift-Enter	Execute the code in the first cell.
5	Shift-Enter	Execute the code in the second cell.
6	Repeat executing the cells until the last cell

Notebook commands

Working with a Notebook is rather intuitive. Here are some commands you will often use.

Command	Comment
Shift-Enter	Execute code and create a new cell below.
Ctrl-Enter	Execute code and stay in the cell
Tab	Code completion, e.g. printl-Tab => println.
Double Tab	List with options, e.g. print-Tab displays `print, println, and printstyled`
\sqrt-tab	Special characters, in this case `√`.
Esc-A	Create an empty cell above the current cell.
Esc-B	Create an empty cell below the current cell.
Esc-M	Change to a markdown cell.
Esc-Y	Change to code cell.

Click on the keyboard icon to see more options.

Exercise 14.1: Run a Website

The second example is a notebook website.ipynb that starts a website where users can find information about unpaid invoices and the general ledger. The requirement is that the data files exist.

Summary

Julia supports Jupyter Notebooks, for which you use the package IJulia. In Notebooks, you can give textual explanations to the code. This makes it a suitable tool for course material. Especially since you can add cells afterward and experiment with your code.

For sending information, we use the actor model. Actors process independently and communicate with each other via messages. It makes it easy to set up a workflow.

In the second notebook website.ipynb we show how to create a website. You can also use the code in a Docker container, which we will show in the next chapter.