Session 2 - Understanding Blockchains and Gitlab

In this session, after making a quick recap of Session 1, we continue understanding blockchain systems.

Understanding Blockchains (cont.)

• Anatomy of a Bitcoin-like Blockchain
• Confirmation of Blocks
• Blockchain Systems and Consensus
• Transactin Life-Cycle with a Trusted Ledger Service
• Going Decentralized with a Replicated Ledger Service
• Attacks to Bitcoin-like Blockchains

Understanding Git and Gitlab

Creating a Gitlab Group

Go to Gitlab.com and create a new Gitlab group for your team:

• Group name: your group's name
• Visibility level: private
• Role: Development Team Lead
• Who will be using this group?: My company or team
• What will you use this group for?: I want to learn the basics of Git
• Do not invite members, we will do after.

Click Create Group, you will be directed to your new group’s Gitlab page.

Inviting Members to a Gitlab Group

Go to Group Information -> Members and click Invite Members.

• GitLab member or email address: Gitlab member user name
• Select a role: Maintainer

Click Invite, and continue doing the same until you add all team members.

Finally, add your instructor, Gitlab username @ogurcan, to your group as Owner.

Creating a Gitlab Project

Go back to the main page of the Gitlab group (click on the group’s name on the leftmost corner).

• Click Create Project
• Select Create Blank Project
• Project Name: Hello World
• Project description (optional): Test project
• Project deployment target (optional): No deployment planned
• Visibility Level: Private
• Initialize repository with a README: Yes

Click Create Project, you will be directed to your new project’s Gitlab page.

Creating an Project Issue

On the project’s main page, click New Issue.

• Title: Create the Hello World Java project
• Type: Issue
• Description: Create a Java project named Hello World using your IDE (Eclipse or IntelliJ) and share it on this Gitlab project.
• Assignee: Choose the team member that will push the code

Click Create Issue, you will be directed to your new issue’s Gitlab page.

Then click Create Merge Request.

• Assignee: one of your team members
• Reviewer: @ogurcan

Click Create Merge Reuqest, you will be directed to your new merge request’s Gitlab page.

Cloning a Gitlab Project

Go back to the main page of the Gitlab project (click on the project’s name on the leftmost corner).

• Click Clone
• Copy the url of Clone with SSH
• Open your IDE (Eclipse or IntelliJ)
• Click Clone a Git project
• Use your Gitlab username and password if asked
• Click Next and Finish

Creating and Sharing a New Java Project

Now create a new Java project using File -> New -> Java Project.

• Project name: Hello World
• JRE: Java11 or higher
• Module name: helloworld

For sharing the project on Gitlab, right click on the project and select Team -> Share Project...

• Repository: hello-world

Click Finish.

Now select Window -> Show View -> Git Staging.

• Add all files as Staged Changes
• Commit message: #1 Create the Hello World Java project
• Click Add Signed-off-by
• Click Commit and Push

Go back to the Gitlab page of your merge request. You will see that your commit has been added. Wait for the reviewer to make his/her comments.

Adding a New Feature to a Project

Now that the Java project is ready and shared on Gitlab, we can go on improving it.

• Create a new issue for creating a HelloWorld class with a main() method.
• Create a dedicated merge request. This will create a dedicated branch on git.
• In Eclipse make a git pull to fetch the new branch, and then git check-out this branch as a local branch.
• Upon execution, this application should print Hello World! on the terminal and terminate.
• Push the contribution using