Software Design Architecture Comparison

Revision as of 08:31, 14 February 2016

Background:

What is the rational for this activity?

For students, who are often novice and beginner developers, it is critical to understand the big-picture when jumping into a new software project. A proper view of the system-wide architecture can bring context on how the entire system works, instead of focus on a particular component. When you can have knowledge of other pieces of the puzzle, you tend to implement better code because it is thoughtful of how your current focus interacts with functionality around it and even to functionality seemingly far-removed. Students need to be aware of why this helps them and their career, how to find this kind of documentation, and that it might shape their opinions and focus when choosing projects to interact with.

Are there any similar activities?

See OpenMRS_Design_Reverse_Engineering_Activity_(Android_App) for an activity that has students reverse engineer a design / architecture from an existing open source Android applications codebase.

Directions:

Part 1: Discover Eclipse and OpenStack

In this activity, we will focus on the Eclipse IDE (Platform) project and the OpenStack cloud project. Below, you will learn about these projects and their open communities. After this, you will compare and contrast the design and architecture artifacts available in these communities. Both projects are open source and very large, with many hundreds of participants. Be aware that you will not be able to immediately jump into the code of these projects. We will take a process below where we progress our knowledge bit by bit. You can easily use this process again for future projects.

Because these are projects that you may know little or nothing about, first delve into the basics:

• Gather a quick understanding of each project from a user's point of view.
• What functionality does each project provide its users? It may be helpful to read third party reviews or descriptions, as wikipedia and project websites often do not have beginner descriptions that give you enough context.
• Next, gather some technical statistics. Use tools such as Ohloh (now OpenHub) to get general technical stats and background.
• What programming languages are used? Which one(s) is major, which ones are minor?
• What percentage of the code are comments?
• Mention other general statistics or information that might be helpful when reading into a projects design and architecture.

Part 2: Find Design and Architecture Artifacts

The next step is delving into the high-level design or architecture of each project. Below are a list of required reading resources. In addition to these, you should do your own research to find the most up-to-date resources pertaining to the projects software design and architecture. Software and documentation change drastically over time, so do your own additional research.

Think about and answer the following questions when reading below:

• How do high-level modules and packages work together?
• Does the project have a data layer or store?
• How does each system weave the user into their architecture?
• (bonus) Are there any design patterns that you saw mentioned or that you think might be used? Do not focus on being 100% correct - take some guesses and explain why.

Required Reading:

• Read the following book chapter fully: The Architecture of Open Source Applications - Eclipse chapter
  • By Amy Brown and Greg Wilson; Licensed under CC BY 3.0
• Read the following discussion on OpenStacks developer maillist: Email list discussion on design and architecture
  • Additionally, skim through the following Developers Guide - think to yourself, Does this describe OpenStacks design from a software standpoint?

Look for additional information:

• Find additional readings around design/architecture in Eclipse. Start here:
  • Review the below and attempt to find additional resources; You can often find more up-to-date resources over time as software is changed
  • https://wiki.eclipse.org/Learn_About_Eclipse
  • http://www.eclipse.org/articles/Whitepaper-Platform-3.1/eclipse-platform-whitepaper.pdf
  • http://www.eclipse.org/eclipse/
• Find additional readings around design/architecture in OpenStack. Start here:
  • Logical Architecture - A diagram of their architecture from a user's pov. Think to yourself, does this document give an explanation of their back-end software design?
  • Open Design explanation - Note that this is mostly a description of their Design Summits (gatherings twice a year). Think to yourself, does this explain their software design in-depth?

Part 3: Compare Designs and Architectures

Now that you have scoured the above communities and learned about them at a working-level, we will compare and contrast the documentation, artifacts, and processes found between Eclipse and OpenStack. Questions and a comparative write-up around these differences will be covered.

You will need to write a two-section essay-style paper, one section that answers some specific questions, and another that compares your observations of both communities.

Specific Questions

Write in essay/paragraph style and keep these answers short. 1-3 sentences each. Provide URL links when useful.

Eclipse-specific questions:

• Explain the plugin concept and why it is centrally important to Eclipse.
• Which component model did Eclipse switch to and why?
• Explain Eclipse's decision to refactor and generalize their bundles for RCP applications.
• These design decisions opened their software up to uses they had not dreamt of, such as monitoring the Mars rover. How is this a perfect example of software reuse and modularization?

OpenStack-specific questions:

• How does OpenStack engrain successful design into its code? Recall the discussion at http://lists.openstack.org/pipermail/openstack-dev/2016-February/thread.html#85707
• What are OpenStacks Design summits? How often are they, and what purposes do they serve?
• What are OpenStacks "specs", "blueprints", and "review" processes / tools? How might they effect a developers decisions around design and architecture?
• What is OpenStack Oslo? It has not existed since the start of the project - how did it come about?

Community Comparison

Write a 5 to 10 paragraph (1-3 page) essay that describes:

1. What you found in each community - particularly artifacts not listed above.
2. Which community had more or less of which types of artifacts (architecture diagrams, software design patterns, review processes, etc).
3. What you believe to be the pro's and the con's of each community in respect to software design and architecture. We are looking for your educated opinion here.
4. What could each community learn from each other?

If you get stuck on this, try listing out as many web resources as you can from when you researched each of the communities. Once you list each of them out, side by side, you can draw lines from each side when you see an equivalent resource in the other community. You will be left with matching resources across both communities, and unmatched resources. Now, talk about these similarities and differences in paragraph form.

It is important for you to make an opinion on which community you think is doing what better. There will not be correct or incorrect answers here, but instead the process of how you came to that conclusion and how you defend it, are what will be graded. The act of coming to and defending a position around software design and process can be just as important as implementation details - especially in communities of hundreds of developers, where you will need to understand and convince people of just these things in order to get your ideas included.

Deliverables:

Students will deliver:

1. For Part 1, answers to 8 questions, and possibly 1 bonus question.
2. For Part 2, answers to 3 questions, and possibly 1 bonus question.
3. For Part 3, write an essay-style paper that answers:
   • All Eclipse-specific questions (1-3 sentences each)
   • All OpenStack-specific questions (1-3 sentences each)
   • A 5 to 10 paragraph (1-3 page) essay describing:
     • What you found in each community.
     • Artifact distribution in each community.
     • Pro and con opinions of the two communities studied.
     • Possible lessons learned.

Assessment:

How will the activity be graded?

How will learning will be measured?

Include sample assessment questions/rubrics.

Comments:

What should the instructor know before using this activity?

Encourage students to find new design and architecture information. They should be scouring the sites wiki's, code, documentation, etc. Because these communities are large, their resources will grow and change over time. What was there one semester, may not be there another semester. Or, they may add design documentation that formerly was not there. The links given to students should be a guide - they are not exhaustive.

What are some likely difficulties that an instructor may encounter using this activity?

Additional Information:

Suggestions for Open Source Community:

Suggestions for an open source community member who is working in conjunction with the instructor.

This work is licensed under a Creative Commons Attribution 4.0 International License

Appendix

Note: Can be removed later, or kept as a resource to teaches looking into other communities.

Potential communities to look into:

• Look at openshift’s software architecture
  • Software architecture?
  • Talk to someone on the team - get someone who is an expert and quiz them
• GNOME Shell - graphical environment - UI of Fedora - public iterative design to implementation
• GNOME Documents and Photos - iterative design
• Inkscape community
• Hacking and Contributing files
  • https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#-coding-rules
  • https://github.com/openshift/origin/blob/master/HACKING.md
  • https://github.com/colah/ImplicitCAD/blob/master/hacking.md
  • https://github.com/openstack-dev/hacking/blob/master/HACKING.rst

• Eclipse
  • http://www.aosabook.org/en/eclipse.html
  • https://wiki.eclipse.org/Learn_About_Eclipse
  • http://www.eclipse.org/articles/Whitepaper-Platform-3.1/eclipse-platform-whitepaper.pdf
  • http://www.eclipse.org/eclipse/

• Openstack
  • Email list Discussion on design and architecture
  • Developers Guide - http://docs.openstack.org/infra/manual/developers.html
    • http://docs.openstack.org/project-team-guide/project-setup/python.html
    • https://www.python.org/dev/peps/pep-0008/
    • http://docs.openstack.org/project-team-guide/open-community.html#technical-committee-and-ptl-elections
    • https://github.com/openstack-dev/hacking/blob/master/HACKING.rst
    • hacking.md files, Style Guides, Pep8,
  • User-oriented Architectures
    • Logical Architecture - http://docs.openstack.org/openstack-ops/content/example_architecture.html
    • Conceptual Architecture - http://docs.openstack.org/admin-guide-cloud/common/get_started_conceptual_architecture.html#get-started-conceptual-architecture
    • http://docs.openstack.org/icehouse/training-guides/content/associate-getting-started.html
  • Dev Documentation
    • http://docs.openstack.org/developer/openstack-projects.html
    • http://docs.openstack.org/developer/nova/
  • http://docs.openstack.org/project-team-guide/open-design.html
  • https://wiki.openstack.org/wiki/Blueprints
    • Openstack design process - blueprints idea, where you write feature and how you want to do it, get sign off from community and then patches are reviewed and go through significant revision
  • https://review.openstack.org/#/q/status:open
  • http://docs.openstack.org/infra/manual/developers.html
  • https://review.openstack.org/Documentation/intro-quick.html
  • http://docs.openstack.org/infra/system-config/gerrit.html
  • Openstack Oslo - from email to listserv
    • https://wiki.openstack.org/wiki/Oslo#Principles
    • https://wiki.openstack.org/wiki/Oslo#Design_Proposals
    • http://specs.openstack.org/openstack/oslo-specs/

Background Readings

• https://en.wikipedia.org/wiki/Software_design
• https://en.wikipedia.org/wiki/Software_design_pattern

• Code Complete Book
  • Code Complete - Design chapter
    • ‘Design’ is similar to my definition of ‘software-architecture’, except that design can pervade into lower levels of classes and routines and code

• Gof Design Patterns
  • GoF Design Patterns Explained

• http://stackoverflow.com/questions/704855/software-design-vs-software-architecture
• http://www.openu.ac.il/personal_sites/download/galezer/SoftwareDesign.pdf
  • This paper describes how they had to get students to re-think how they write code. The students needed to think more outside of the syntax of the actual language, and more toward software design / repeatable design patterns that dont depend on the coding language.
  • I am looking at this paper and thinking about the various tasks or activities that they show were done in their classroom. I may be able to use these ideas.
  • “It should be re-emphasized that practical programming does not play a central role in the unit. At the end of the year students and teachers realized that programming in itself is not the main goal.”

• http://stackoverflow.com/questions/268231/how-to-learn-good-software-design-architecture
• Research Paper: Design patterns in open source
• Book: Architecture of Open Source Applications - from Tom
  • http://www.aosabook.org/en/eclipse.html

Project Descriptions

These are being cut for now, because students should figure this out. FIXME think of bringing up a few key sentences to above.

Eclipse is an Integrated Development Environment (IDE) that runs on desktop computers. An IDE is basically a fancy code-editor for developers who are creating software. A developer needs not only edit code in text files, but also to run the code, debug the code (possibly stepping through the code one-line at a time, looking for a bug), they need to see hierarchical views of the classes, and have ease-of-use functions like code completion (you can't remember which function you want to use, and the IDE gives you a list of choices while you are typing). Eclipse centers on Java development, though it is also usable for dozens of other languages. Do not confuse the 'Eclipse IDE' with the 'Eclipse Foundation', which was created after the successful IDE and now encompasses hundreds of open source project.

OpenStack is a cloud infrastructure platform. FIXME Bacon ipsum dolor amet venison short loin porchetta, cow picanha swine corned beef tri-tip fatback pork belly sirloin landjaeger leberkas. Capicola ball tip ham fatback hamburger alcatra short ribs shoulder meatloaf corned beef tri-tip pancetta brisket. Salami biltong kielbasa swine porchetta cupim. Hamburger tongue sirloin drumstick boudin corned beef ham shoulder ground round meatloaf ribeye alcatra tri-tip landjaeger kielbasa. Chicken strip steak kevin turkey drumstick bresaola salami bacon ground round. Kevin picanha sirloin tri-tip jerky.

Generally, OpenStack is a younger faster moving project, so they self-admittedly do not have good documents, process, or artifacts to encourage healthy software design.