Friday, October 03, 2014

A Rails Enthusiast’s take on MEAN.js

Is MEAN.js Node's answer to Rails?  Following the famous blog demo creation using the MEAN.js stack.

This is an article I wrote for InfoQ:

Friday, August 22, 2014

Monday, February 10, 2014

How to get good software from contractors

OR Working with codecraft (me)

I think I have said before, the purpose of software development is to produce good enough software as quickly and efficiently as possible.  Everything I do at codecraft is driven by that principle.  But why just "good enough," and what does it mean exactly?

Good Enough Software

The software created by a project should only be good enough, not more.  That sounds crazy, I know.  But, if we are trying to get to market quickly and make strategic use of our investments, any bit of extra quality or premature scalability or speculative functionality costs money, money we could spend elsewhere.  One has to be serious about how time and money are spent or the competition will clobber you.

Good enough, then, means finding the balance between present and future costs and benefits.  Good enough means investing in what you need most right now, while being conscious of future concerns.  Good enough means getting something inperfect in front of users quickly, and worrying about scale and perfection when the system is viable.

So how do I go about delivering Good Enough, quickly and efficiently?  It is all about providing rich, continuous feedback.

What I Do

Continuous Planning
Every day, the plan will change to respond to where we are and what is the most strategic use of time.  I usually like to keep a prioritized "feature inventory" in a shared document of tracking system.  The client picks priority features, with some elaboration and discussion as necessary, and defines "Stories," pieces of the feature that make reasonable units of work.  Stories move from a Ready state to In-Process with further discussion as necessary, and using the principles of Kanban the in-process work at any time is limited to hone productivity.  Completed code for a story is captured in the shared repository when finished.

Continuous Communication
Using a tool like Campfire or Flowdock, the entire team can share and recall group communications.  Developers will be available continuously (during certain time frames) in this environment.

Continuous Quality
All business logic modules will be supported by automated unit tests and shared with the client as desired.  The user interface will be supported by a reasonable suite of integration tests.  The full test suite should be run before every commit.

Continuous Delivery
All completed source code is kept in a shared repository like GitHub and available at any time to the Client.  I would suggest we use a cloud or PaaS like Heroku or Digital Ocean to host a couple environments, "staging" and the ultimate live site.  As soon as possible, the running application will be available in staging.  Every bit that is committed into the shared repository will immediately be installed into the staging environment for review.  Code is often delivered several times a day.

What I Don't Do

I don't tell you what you want to hear.  I don't pretend to see the future and act like I know what the optimal solution for the client will look like, months from now, much less how much effort it will take.  After all, Estimation is Evil.
Rather than basing the relationship on a contract that gives clients a false sense of security about getting what they need, I prefer to set up a relationship based on trust.  Trust at a personal level, but more importantly a trust in the practices that we will set up together to ensure the best possible use of time and resources.

Wednesday, October 31, 2012

Using a module to share common association logic in Rails

UPDATE:  If I did this again, I would consider packaging the code as a Concern

I recently wanted to DRY up some repetitive Rails association code, similar associations used in multiple models.  This gave me the opportunity to figure out a few tricks, like creating a module Class method and using metaprogramming to add dynamically named accessors.

Anyway, here is the Module:

...and the client model...

Tuesday, August 28, 2012

Building procedures with composition

Often developers need to model a multi-step process.  Also common is the need to reuse pieces of the process:  maybe the steps are the same but the execution of the steps vary for different contexts, or maybe the step flow changes slightly in some cases but the logic of the steps is largely reused.

One common way developers address this situation is to implement a Template Method pattern.  For example, an insurance system might have several similar flows for processing feeds from different sources--partner EDI, consumer web site, provider applications--where many of the steps involved are largely reusable.

A Template Method basically uses inheritance to share common logic, while varying the implementation of steps by overriding methods representing particular steps.  However as the GOF posited and leading developers believe today, one should "favor composition over inheritance."  Inheritance abuse is a common and natural side effect of trying too hard to reuse logic the OO-way, but we can do better.

The essential problem with using inheritance with the Template Method is that the class tree can get pretty ugly if one needs to vary the implementation of steps AND the flow of steps.  Also, more often than not, the is-a relationship between common and specialized processors is restrictive and faulty.  For example if a processor implementation wanted to extend something else like ActiveRecord.

What if, rather than using a template method, one could compose flows of steps, where the steps are pluggable members?  Another way to build processes that can be reused and extended is with the Strategy pattern, where the algorithm (or steps thereof) are pluggable.  Using this approach, the developer creates the structure of the flow in one class but delegates the execution of steps to collaborators.

Now what if there was a fluent interface for building flows of plugable steps, as well as machinery and conventions for coordinating between steps?  Well, that is the idea of Flo:
Some of the ideas from Spring Batch and Apache Camel have also inspired my thinking here, but Flo is much simpler and less specialized.  I was also motivated by the Unix programming model, little tools that do one thing well, strung together with pipes.

Note that Flo is a work in progress, awaiting her first real application.

Monday, June 18, 2012

Controlling Rails mass-assignment with whitelists and :as

Rails 3.2 has some flexible features for controlling mass-assignment. A little Gist I put together demonstrates:

 whitelisting and roles: