Tuesday, April 25, 2017

Modules vs. Monoliths vs. Microservices:

Dan Bader (@dbader_org)
Worth a read: "Modules vs. Microservices" (and how to find a middle ground) oreilly.com/ideas/modules-…

"don't trick yourself into a microservices-only mindset"

Thanks for sharing.

The referenced post gives you the freedom to have a "big-ish" microservice. My current example has four very closely-related resources. There's agony in decomposing these into separate services. So we have several distinct Python modules bound into a single Flask container.

Yes. We lack the advertised static type checking for module boundaries. The kind of static type checking that doesn't actually solve any actual problems, since the issues are always semantic and can only be found with unit tests and integration tests and Gherkin-based acceptance testing (see Python BDD: https://pypi.python.org/pypi/pytest-bdd and https://pypi.python.org/pypi/behave/1.2.5).

We walk a fine line. How tightly coupled are these resources? Can they actually be used in isolation? What do the possible future changes look like? Where is the swagger.json going to change?

It's helpful to have both options on the table.

Wednesday, April 19, 2017

AWS "Serverless" Architecture Update -- Python 3.6 News

This: https://aws.amazon.com/about-aws/whats-new/2017/04/aws-lambda-supports-python-3-6/

You can now use Python 3.6 Lambdas. This changes things dramatically. We can now write faster, simpler, less quirky code using the latest-and-greatest Python.

If you want to configure a server in the cloud, consider this: https://wiki.ubuntu.com/Python. Use Ubuntu as the base image. Faster. Cleaner. Less Quirky.

Tuesday, April 4, 2017

Coding and "Inspiration"

Data Science Renee (@BecomingDataSci)
Thread. Coding is inherently frustrating. Expect that. But with puzzle-solving healthy attitude, keep going. Don't give up on yourself! twitter.com/IsabellaGhemen…

This thread includes some interesting topics. What hit me was the idea of "inspiration-driven coding."
"Do you ever get frustrated when coding? Or is it all inspirational?" 
"go into obsessive mode until I fix the problem"
This is fascinating. I've been coding for -- well -- a looooong time. I no longer recall a time when I struggled. These quotes provide some insight into the barrier that some people find between them and a finished project.

I think that "hard-part-do-later" is bad advice. I'm a big fan of tackling the hard part first.

I find that I have to do several things to get software to work. And I do these so often that I rarely think about doing them, so I might be misstating what I'm really doing. But I think this is right:

  • Understand the problem. It helps to understand the problem being solved. It's not essential to understand all of the problem. In a lot of cases, the problem is a larger-scale "business" issue which stems from a regulatory or competitive climate that has a very huge context including human aspirations and the very nature of what it means to be human. In these cases, narrowing the focus of the problem helps. Stating the problem clearly really helps. Clarifying the context can help; but it may involve erecting random-seeming boundaries to keep the problem from involving too many imponderables.
  • Understand the solution. This is easy to turn into glib useless advice. But I think that one thing that really helps is to really carefully detail what "success" means. For small things (like functions or classes) it should be a dry, formal assertion about the state of the variables. Without a mathematical formalism, it's easy to get confused and write a function that doesn't do the right thing. For larger-scale features, the solutions pieces need pretty complete, formal descriptions of how we know that they worked. File formats. Messages. Swagger specifications for an API. 
  • Understand the technology. This can be hard. For simple programming, the technology is the set of language constructs. For more sophisticated programming, the technologies are the libraries and packages available. When it comes to big data, these can be very large and complex packages (like pandas and numpy) with lots and lots of features. It's very easy to overlook features when searching through documentation. For integration of components, it's an understanding of what the various tools really do. (Example: I'm trying to get a grip on Docker, and there are a lot of commands that do a lot of things, and I have to be careful to understand the difference between "run" and "start".)
But how? How do we "understand" these things?

I'm a big fan of writing down everything. I really like the idea of "literate programming:" write down the problem. Write down the overview of the solution. Write down the technologies that will be used. Detail the coding assertions and outcomes. Detail the components being used. Write. Write. Write.

The first drafts will be all natural language. Summaries. Overviews. Hand-wringing over alternatives and tradeoffs and possibilities. That's okay. Writing helps. Write. Write. Write. 

Describe how simple it "should" be. Describe how the inputs get transmogrified to the outputs. Fantasize. 

Then elaborate on the details of "how" this will get done. Confirm the fantasy statements of how the various bits and pieces fit together. Revise. Revise. Revise.

At some point, parts will start to map to code in obvious ways. and there will be a break from natural language to more formal code. This may happen gradually. Or it may happen all at once.

One of the best pieces of coding advice was something I saw many years go.

"Write all the comments first." 

The example that followed showed a "wire frame" program that had some declarations, but was mostly blocks of comments describing -- in vague, general ways -- what would go here eventually. I like this approach because it allows space to think at a high level about how things fit together as well as space to think about details of how each individual little thing works.

There's a kind of progressive filling-in-the-blanks as code evolves into the frame.

Then A Miracle Occurs

Perhaps most important is this. Starting with wire-frame comments and natural language narratives can lead to identification of gaps in understanding the problem, the solution, or the technology. I think that these conceptual gaps are where the frustration grows.

This is why I think that the big problem is caused by "hard-part-do-later" thinking. It can turn out that the "hard part" required a miracle. 

There's a famous S. Harris cartoon (visit http://www.sciencecartoonsplus.com/pages/gallery.php) which has the "then a miracle occurs" step in the middle of a process. 

A wire frame for code is a low-cost, low-investment, low-emotional-content product. As code fills in, it may become clear that the wire frame wasn't right. It's easier to discard a hundred lines of comments once we realize that they're not quite right. There's less emotional investment. It's easy to throw it away and start again.

Indeed, we may have to go through a few wireframes to be really clear on where we think the miracle will occur. This gives us a chance to identify the hard part of the problem. 

Once we've got the hard part identified, we can tackle that. It may involve one of three kinds of deeper understanding:
  • Understanding the problem better,
  • Understanding the solution in more detail, or
  • Understanding the technology more completely.
Any combination of these may be the reason why some part is hard. We'll have to fix our understanding before we can finish. We may as well tackle it first, since we're going to have to do it anyway.

It's best to look for alternatives before we've written too much code. There's an emotional commitment to code, even if it doesn't work right. It's hard to throw code away. Therefore, stall as long as possible. Solve the hard parts. Commit to code last.  

Tuesday, March 28, 2017

Linked-in Learning: Migrating from Python 2.7 to Python 3

Migrating from Python 2.7 to Python 3
with: Steven Lott

...is now available on LinkedIn Learning:
https://www.linkedin.com/learning/migrating-from-python-2-7-to-python-3

and on Lynda.com:
https://www.lynda.com/Python-tutorials/Migrating-from-Python-2-7-Python-3/560887-2.html

Course Description:
Are you still using Python 2.7? If you've been meaning to make the jump to Python 3, but aren't entirely sure what's different in the latest version of this popular language—or how to migrate your code—then this course is for you. Instructor Steven Lott illuminates the differences between the two Python versions, going over elements such as changes to built-in Python functions and the Python standard library. He also walks through a number of ways to convert your Python 2.7 applications to Python 3, showing how to use packages like six, future, and 2to3. Along the way, Steven shares his own experiences with this transition, and offers helpful suggestions for enhancing the overall quality and performance of your code.

Topics Include:
Reviewing the differences between the two versions
Reviewing the syntax changes introduced with Python 3
Understanding the changes to built-in functions
Reviewing the most important changes to the Python standard library
Understanding which tools are required to migrate from Python 2.7 to Python 3
Using six to handle class definitions
Using six with standard library changes
Using future
Making syntax changes and class changes with futurize
Using 2to3 or modernize

Duration:
2h 40m