Spring Boot with Groovy config

While working on converting a Grails application to a SpringBoot based application, I was trying to understand how the auto configurations and custom configurations work under the hood. Just like CoC of Groovy/Grails, there seems to be a lot of hide-and-seek going on under the Spring boot hood. Admittedly its been a while for me with good ol’ raw Spring, so the many different ways of skinning the configuration felt a bit overwhelming. I counted several concepts around configurations – application.properties, application.yaml, PropertySource, PropertyPlaceHolder, @Value, @EnableConfiguration, @EnableConfigurationProperties, @EnableAutoConfiguration, @Configuration, @ConfigurationProperties, pre-defined property name prefixes, creating classes specifically for holding configuration values – so much information just for accessing key-value pairs? Compare to Grails – one Config.groovy (or multiple externalized) and a simple grailsApplication injection takes care of making configuration available anywhere. When I read Spring Boot support for Groovy, I somehow assumed that support for a groovy config is automatically enabled.

My Grails application already had a groovy config, and I was not in a mood to convert them to .properties or .yaml. Groovy configs are DSLs in essence – it provides many advantages over the traditional properties file: key=value (like .properties), a structured format like .yaml – sans the indent-erasure-phobia, type-enriched config values like list/map etc, functions via closures and more.

So, here is a very simple way to expose the groovy config to your Spring Boot apps:

Create a Config.groovy in the same folder as the ConfigProperties class.

/** Config.groovy **/

//simple key-value
spring.boot.guide = 'https://github.com/spring-guides?page=1'
//formatted structure
google {
searchurl = 'http://www.google.com'
apiKey = '1234'
}

/** ConfigProperties.groovy **/

import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration

@Configuration
class ConfigProperties {

@Bean(name="configObject")
ConfigObject configObject() {
return new ConfigSlurper().parse(Config)
}

}
/** HelloController.groovy **/

import ConfigProperties
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController

@RestController
class HelloController {
@Autowired
ConfigObject configObject

@RequestMapping("/")
String home() {
return "Hello World! " + configObject.spring.boot.guide
}

}

/** Application.groovy **/

@EnableAutoConfiguration
@ComponentScan
class Application {
static void main(String[] args) {
Object[] sources = [Application.class, ConfigProperties.class]
SpringApplication.run(sources, args)
}
}

Note: @Bean returns must be typed. Habitually, I wrote def configObject() { return new ConfigSlurper().parse(Config) } and the @Autowired did not wire it up.

Grails Application with AngularJS: Calling a Rest Service – Part 5

Remember the core principle of MVC? Clean separation of model, control and view? Many MVC frameworks, but there hardly is a single framework that provides a puritanical separation between layers. In some, the view is polluted with server-side syntax (jsp, gsp, asp), its equivalents (taglib) or specialized templates (velocity, freemarker); in some others, the server-side code is interspersed with view layer abstractions (css class, href links) or its equivalent html wrappers. One way to measure good separation is how close the view layer is to html semantics itself.

In this part, let us see how we can combine the power of Angular and simplicity of Grails (mainly because of conventions) to make a better separation of model and view.

Note: For the brevity of this post, the tests are not explained, but is included in the github. Specifically, take a look at how angular-mocks provides a cool $httpBackend object that acts as a http service for unit tests and how to invoke them in the controllerSpecs.js.

Goal: Display a star catalog

Techniques Demonstrated

  1. Retrieve Star catalog from server via ajax rest call (demonstrates Rest, Ajax and Angular’s $http)
  2. Show/Hide star catalog (demonstrates Angular’s implicit scope values)
  3. Display the json model in table format (demonstrates Angular’s ng-repeat directive)
  4. Simple Grails 2.3.x Rest services (demonstrates Grails 2.3.x Rest capabilities)

Ingredients

  • Star domain class, decorated with @Resource annotation to make it Rest-enabled
  • New Angular controller to initiate an http request
  • http.get() ajax call to retrieve data from Star domain class and bind to Angular scope
  • Html table to display scope data

Step: Create Star domain class

cmd> cd c:\projects\angrails
cmd> grails create-domain-class angular.Star

Update the code as:

package angrails
import grails.rest.Resource
@Resource(uri='/starCatalog', formats=['json', 'xml'])
class Star {
String name
 String constellation
 //Bayer Designation
 String bd
 //Distance from Earth in light years
 Integer distance
static constraints = {
 }
}

There are many ways to create restful services in Grails 2.3.x, this is one of the easiest ways – create a domain object and add a @Resource annotation. Works for prototypes, demos and really simple applications. For an advanced method, you may want to use RestController and other methods.

Step: Add some seed data to Bootstrap.groovy

def init = { servletContext ->
 new Star(name: 'Aldebaran', constellation: 'Taurus', bd: 'Alpha Tauri', distance: 65).save(flush:true)
 new Star(name: 'Betelgeuse', constellation: 'Orion', bd: 'Alpha Orionis', distance: 640).save(flush:true)
 new Star(name: 'Regulus', constellation: 'Leo', bd: 'Alpha Leonis', distance: 79).save(flush:true)
 new Star(name: 'Spica', constellation: 'Virgo', bd: 'Alpha Virginis', distance: 260).save(flush:true)
 }
cmd> grails run-app
Goto http://localhost:8080/angrails/starCatalog

You should see json representation of the records from Star domain class. Grails auto-generates Rest url end point /starCatalog.

Step: Create Angular Controller and http.get ajax call

Create another controller (next to the MainCtrl) in angrailsApp.js:

angrailsApp.controller('StarCatalogCtrl',
	function ($scope, $http) {

		$scope.getStarCatalog = function () {
			$http.get('/angrails/starCatalog').
				success(function (data) {
					console.log("success: " + data);
					$scope.starCatalog = data;
				}).error(function (data) {
					console.log("error: " + data);
					$scope.starCatalog = data;
				});
		};

		$scope.getStarCatalog();
	}
);

1. As a convention, I keep Angular controller suffix as “*Ctrl”, while Grails controllers as “*Controller”.
2. Observe that one more parameter is being added to the function – $http. When Angular runs the javascript, it injects a http service object into $http automatically.
3. The $http.get() does the ajax call to the auto-generated Grails Rest endpoint
4. The result data is set to a new variable in scope – “starCatalog”. We will use this variable to display the table data

Step: Display data in table

You can run crazy with your imagination on how to display the data, but a simple step is shown here:

<div ng-controller="StarCatalogCtrl">
	<span><a href="#" ng-click="starCatalogShow = !starCatalogShow">Star Catalog</a></span>
	<div ng-show="starCatalogShow">
		<div>
			<table class="table">
				<tr>
					<th>Common name</th>
					<th>Constellation</th>
					<th>Bayer Designation</th>
					<th>Distance from Earth (light years)</th>
				</tr>
				<tr ng-repeat="star in starCatalog">
					<td>{{star.name}}</td>
					<td>{{star.constellation}}</td>
					<td>{{star.bd}}</td>
					<td>{{star.distance}}</td>
				</tr>
			</table>
		</div>
	</div>
</div>

A few points of interest here:

  • AngularJS Directives (ng-show, ng-click, ng-controller, ng-repeat) do appear to be a cleaner way of extending html behaviour.
  • Directive ng-controller=StarCatalogCtrl specifies which controller provides the scope of the data
  • How an implicit scope variable “starCatalog” hides/shows the table (within the span tag, using the ng-show directive)
  • The ng-repeat Angular directive which is the “forEach (item in itemList)” equivalent to iterate through the starCatalog
  • With this approach, the binding between client and server is a clean http call. This gives you the ability to call any rest service, as long as you can process what you get.

And before we go nuts about AngularJS, observe the syntax of the <a> tag. This type of construct was popular pre-jquery times (<a href=”#”, onclick=”javascript:openLink()”>Click me</a>). With jQuery, there was a big drive towards separation of presentation of data and manipulation of data – using $(id).onClick() syntax. But AngularJS has put the old construct right back into vogue now, but with a twist.

Does this bother you? The pendulum of imperative-declarative programming will swing on forever. Meanwhile, take a look at these articles about Remix and Innovation Recycle bin.

Grails Application with AngularJS: Tests on build server – Part 4

In the previous post, we got karma running on your local systems, as part of grails unit test plans, enabling continual test against Chrome. How do you ensure your unit tests are running in a build server like Jenkins or Bamboo?

PhantomJS is a headless webkit, ie a browser with no browser UI. Make these changes in your karma.conf.js

browsers: ['Chrome', 'PhantomJS'],
plugins: [
 'karma-jasmine',
 'karma-chrome-launcher',
 'karma-phantomjs-launcher',
 'karma-remote-reporter'
 ]

Now run the karma test again:

cmd> cd c:\projects\angrails
cmd> karma start test\javascript\config\karma.conf.js

Warning: Native modules not compiled. XOR performance will be degraded.
Warning: Native modules not compiled. UTF-8 validation disabled.
INFO [karma]: Karma v0.10.9 server started at http://localhost:8001/
INFO [launcher]: Starting browser Chrome
INFO [launcher]: Starting browser PhantomJS
INFO [Chrome 33.0.1750 (Windows 7)]: Connected on socket Tsk76f8qRWk84nVP6jlC
INFO [PhantomJS 1.9.2 (Windows 7)]: Connected on socket oMQSWXNcCW6hNOoH6jlD
PhantomJS 1.9.2 (Windows 7) LOG: ‘angrails manifest load complete.’
PhantomJS 1.9.2 (Windows 7) LOG: ‘calling’
Chrome 33.0.1750 (Windows 7) LOG: ‘angrails manifest load complete.’
Chrome 33.0.1750 (Windows 7) LOG: ‘calling’
Chrome 33.0.1750 (Windows 7): Executed 1 of 1 SUCCESS (0.352 secs / 0.029 secs)
PhantomJS 1.9.2 (Windows 7): Executed 1 of 1 SUCCESS (0.273 secs / 0.018 secs)
TOTAL: 2 SUCCESS

Notice that Karma runs tests against PhantomJS too. You can also add Firefox, IE and test your javascripts against multiple browsers simultaneously.

Additional Notes

But for your build server you need to test just against PhantomJS and not other browsers. One way to do this, is to create a copy of karma.conf.js as karma.local-conf.js. Use the local copy for your local unit tests and the default karma.conf.js for the builds (ie only PhantomJS). This way grails test-app runs against the karma.conf.js in your build server.

Remember you need to install node.js, karma and other components in the build server too.

In Part 5, we shall see how to invoke grails urls/services from AngularJS.

Grails application with AngularJS: Karma with test-app – Part 3

In Part 2, we added karma test runner to our AnGrails application. Its great that you can test your javascripts on the fly locally. What about testing it as part of your grails test-app lifecycle ?

Step: Setup JUnit/Karma integration so that karma can run via grails test-app

Edit BuildConfig.groovy

Add the following line under plugins

test ':karma-test-runner:0.2.0'

See karma-test-runner grails plugin for more information.

Create new file c:/projects/angrails/test/unit/angrails/JavaScriptUnitTestKarmaSuite.java

Add the following text:

package angrails;
import de.is24.util.karmatestrunner.junit.KarmaTestSuiteRunner;
import org.junit.runner.RunWith;
@RunWith(KarmaTestSuiteRunner.class)
@KarmaTestSuiteRunner.KarmaConfigPath("./test/javascript/config/karma.conf.js")
@KarmaTestSuiteRunner.KarmaRemoteServerPort(9876)
public class JavaScriptUnitTestKarmaSuite {
}

Run the test.

cmd> grails test-app

| Compiling 1 source files.....
Karma will be started with process builder args: [karma.cmd, start, C:\projects\angrails\.\test\javascript\config\karma.conf.js]
| Running 1 javascript test...
Starting karma result receiver server on localhost:9889
Warning: Native modules not compiled. XOR performance will be degraded.
INFO [karma]: Karma v0.10.9 server started at http://localhost:8001/
Warning: Native modules not compiled. UTF-8 validation disabled.
INFO [launcher]: Starting browser Chrome
INFO [Chrome 33.0.1750 (Windows 7)]: Connected on socket yX5XSRbnYl_IzwQp7ocG
LOG: 'angrails manifest load complete.'
LOG: 'calling'
Chrome 33.0.1750 (Windows 7): Executed 1 of 1 SUCCESS (0.248 secs / 0.03 secs)

Issues

If one of the following errors occur:

Could not load class in test type ‘javascript’
ERROR [karma]: { [Error: listen EACCES] code: ‘EACCES’, errno: ‘EACCES’, syscall: ‘listen’ }

There is some issue with how the karma is being started via test-app. I found both cmd line grails test-app and invoking via IntelliJ grails cmd window (Alt+G) yield different results. The common problem of both errors seems to be the port number that karma starts on.

Solutions

1. Change the port number in karma.conf.js to 8001 or try another number (above 1024 and available).
2. Remove line of the port number specified in JavaScriptUnitTestKarmaSuite.java: @KarmaTestSuiteRunner.KarmaRemoteServerPort(8001)

Results

With the above settings (ie karma.conf.js:port = 8001 and no port specified in the java code), the test-app works fine in both IntelliJ and command line.

During your test runs, sometimes the port binding is not released when test is shutdown. On *nix systems, you can just use kill <process-id>. For Windows, use PowerShell and do the following:

netstat -o -n -a | findstr "<portnumber>"
stop-process -Id <pid>

In Part 3, we saw how to add karma to grails test-app lifecycle.
In Part 4, lets see how to get karma tests running on your build server.

Grails application with AngularJS: Adding Karma – Part 2

Step: Install karma, karma cli and angular-mocks

cmd> cd c:/projects/angrails
cmd> mkdir test\javascript\config
cmd> mkdir test\javascript\unit
cmd> mkdir test\javascript\lib
cmd> npm install -g karma
cmd> npm install -g karma-cli
cmd> cd c:/projects/angrails/test/javascript/lib

As of this writing, angular-mocks is at v1.2.14 and does not work with angular v1.2.12. When Karma is run, it fails with following error:

Failed to instantiate module ngMock due to Unknown provider: $$rAFProvider

I had to go back to a previous version of angular-mocks v1.2.3. So install v1.2.3:

cmd> bower install angular-mocks#1.2.3

Both angular and angular-mocks will be installed in c:/projects/angrails/test/javascript/lib/bower_components. You can delete the “angular” directory, because we already included it in the grails-app/assets. You would rather not want two angular imports in your project, as you must remember to update both for version changes.

Step: Configure karma

cmd> cd c:/projects/angrails/test/javascript/config
cmd> karma init karma.conf.js

#Answer in the following manner (of course you can choose to answer differently)

Which testing framework do you want to use ?
Press tab to list possible options. Enter to move to the next question.
> jasmine
Do you want to use Require.js ?
This will add Require.js plugin.
Press tab to list possible options. Enter to move to the next question.
> no
Do you want to capture a browser automatically ?
Press tab to list possible options. Enter empty string to move to the next question.
> Chrome
>
What is the location of your source and test files ?
You can use glob patterns, eg. "js/*.js" or "test/**/*Spec.js".
Enter empty string to move to the next question.
> ../../../grails-app/assets/bower_components/jquery/dist/jquery.js
> ../../../grails-app/assets/bower_components/angular/angular.js
> ../../../grails-app/assets/javascripts/**/*.js
> ../../../test/javascript/lib/bower_components/angular-mocks/angular-mocks.js
> ../../../test/javascript/unit/**/*.js
>
Should any of the files included by the previous patterns be excluded ?
You can use glob patterns, eg. "**/*.swp".
Enter empty string to move to the next question.
>
Do you want Karma to watch all the files and run the tests on change ?
Press tab to list possible options.
> yes
Config file generated at "c:\projects\angrails\test\javascript\config\karma.conf.js".

Optionally, you can edit the karma.conf.js and set the basepath to: basePath: ‘./../../../’, and remove the ../../../ from the file includes.

Step: Start Karma

cmd> karma start karma.conf.js

You should see a chrome browser started pointing to 9876 port. There is nothing to test yet. Keep the Karma running.

Step: Add Angular code

Add a test: test/javascript/unit/controllersSpec.js

'use strict';
describe('angrailsTest', function () {
beforeEach(module('angrailsApp'));
var scope, mainCtrl;
beforeEach(inject(function ($compile, $rootScope) {
 scope = $rootScope.$new();
 }));
describe('angrailsMainCtrl', function () {
beforeEach(inject(function ($controller) {
 mainCtrl = $controller("MainCtrl", {$scope: scope});
 }));
it("should set hello text", function () {
 var helloText = 'Hello Angular Demo!';
 expect(scope.helloText).toEqual(helloText);
 });
})
});

Angular Application module: grails-app/assets/javascripts/angrailsApp.js

var angrailsApp = angular.module('angrailsApp', []);
angrailsApp.controller('MainCtrl', ['$scope',
 function ($scope) {
 $scope.helloText = 'Hello Angrails Demo!';
 }
])

Application dependencies: grails-app/assets/javascripts/application.js

Add line between angular and views:

//= require angular/angular
//= require angrailsApp
//= require_tree views

When you modify the js files, keep watching the karma window, it will run tests automatically. Currently it must have failed, because our test is incorrect:

In controllersSpec.js, change

var helloText = 'Hello Angular Demo!';

to

var helloText = 'Hello Angrails Demo!';

and watch the Karma window, it should pass.

In Part 2, We added Karma to our application. Karma can test javascripts independently. What if we want to test it as part of our grails test lifecycle?

In Part 3, lets ensure that Karma is part of the grails application test lifecycle.

Grails application with AngularJS: Setup – Part 1

There are several posts about setting up AngularJS, but a few specific to Grails environment. If you have been a Grails developer and want to explore using AngularJS framework for front-end, here is step by step guide to get started. Grails and AngularJS are both full-fledged mvc frameworks on their own. Using the positives from both can be a killer comination to build fast and modern dynamic web applications.

Notes:

  • Instructions are for Windows OS
  • Directories only for reference
  • All versions as of writing this article. Substitute with newer versions as appropriate.
  • Pre-installed: JDK 1.7.0_51: C:\Programs\Java\jdk_1.7.0_51
  • Pre-installed: Grails 2.3.6: C:\Programs\Grails\grails-2.3.6

This setup does not use the angularjs-resources Grails plugin. It replaces the resources plugin entirely with asset-pipeline plugin and uses npm/bower to manage javascript dependencies directly. AngularJS does work with grails resources plugin too, but I feel it becomes difficult to maintain when adding more angular modules.

Step: Install pre-req software

Install Node.js -> http://nodejs.org/ to C:\Programs\nodejs
Install Git -> http://git-scm.com/downloads

Ensure PATH contains: c:\programs\nodejs; c:\programs\git\cmd

Open new command prompt (new, because your PATH would have been modified)

npm install -g npm
npm install -g bower

Step: Create new Grails app

cmd> cd c:\projects
cmd> grails create-app angrails
#All commands executed from the following directory, unless specified
cmd> cd angrails

Step: Switch from resources plugin to using asset-pipeline plugin

AngularJS will work with resources plugin too, but when you start installing many javascript components, the ApplicationResources can become clumsy. Asset pipeline is the new Grails plugin (based on Rails asset pipeline) that makes it easier to manage static resources, javascript, sass/less etc.

Edit BuildConfig.groovy

delete: resources, zipped-resources, cached-resources, yui-minify-resources lines

add: compile “:asset-pipeline:1.6.1″

cmd> grails refresh-dependencies

That will create grails-app/assets/* sub-directories

cmd> move web-app\css\* grails-app\assets\stylesheets
cmd> move web-app\js\* grails-app\assets\javascripts
cmd> move web-app\images\* grails-app\assets\images
cmd> move web-app\images\skin grails-app\assets\images
cmd> rmdir web-app\css web-app\js web-app\images

Step: Fix main.gsp to use asset-pipeline

Edit main.gsp

Comment/Delete following lines:

<link rel="shortcut icon" href="${resource(dir: 'images', file: 'favicon.ico')}" type="image/x-icon">
<link rel="apple-touch-icon" href="${resource(dir: 'images', file: 'apple-touch-icon.png')}">
<link rel="apple-touch-icon" sizes="114x114" href="${resource(dir: 'images', file: 'apple-touch-icon-retina.png')}">
<link rel="stylesheet" href="${resource(dir: 'css', file: 'main.css')}" type="text/css">
<link rel="stylesheet" href="${resource(dir: 'css', file: 'mobile.css')}" type="text/css">
<g:javascript library="application"/>
<r:layoutResources/> (2 places)

Add the following lines above <g:layoutHead/>

<asset:javascript src="application.js"/>
<asset:stylesheet href="main.css"/>
<asset:link rel="shortcut icon" href="favicon.ico" type="image/x-icon"/>

Any other ${resources} images, replace with <asset:image src=”– filename –”/>

Delete ApplicationResources.groovy

Step: Add jQuery dependency

cmd> cd c:/projects/angrails/grails-app/assets
cmd> bower install jquery
cmd> bower install angular

That will create bower_components directory and the js libraries (inside grails-app/assets/bower_components)

Step: Add Javascript dependencies

Edit grails-app/assets/javascripts/application.js

Replace the content with:

//= require jquery/dist/jquery
//= require angular/angular
//= require_tree views
//= require_self
console.log("angrails manifest load complete.");

Note that when using //=require you do not specify the bower_components directory. Asset-pipeline plugin skips the first directory after grails-app/assets.

cmd> grails run-app
Goto http://localhost:8080/angrails

End of Part 1: We have installed AngularJS and asset-pipeline for a Grails app.

In Part 2, we shall install Karma Test Runner for testing AngularJS javascripts.

Taming of the Pair Programmer

In a recent project at work, I went through an intense experience of pair programming with some of the thought leaders in pair programming work model. While I enjoyed the experience, I do feel that pair programming psychology has been given a serious miss.

So I visited the world famous psychiatrist Dr. Pear for consultations but unfortunately, the notes were leaked out due to a security breach from the cloud platform where the medical records were stored. Here is the transcription.

Dr.Pear: Hello! (looking at my records) May I know the reason for your visit today?
Me: Sure Dr. Pear. I have been having some delusions about pair programming and I want to understand how to overcome pair programming anxiety.
Dr.Pear: (notes down): Oh, a case of PTPPSD (Post Traumatic Pair Programming Stress Disorder). Have you tried the OTC medicine – Pairitin ?
Me: Yes, doctor. But it hasn’t helped, obviously. Placebo.
Dr.Pear: Oh, well … Ok, I have a few questions. Can you describe your regular office day?
Me: I check my mails while driving to office, reply to them on the elevator, get a cup of coffee, then find a pair and start doing things. We switch roles of driver-navigator till the end of the day. And the next day we switch pairs and do the same stuff.
Dr.Pear: Sounds normal. What about breaks?
Me: Yeah, we do take breaks. And I always explicitly communicate what I am about to do – whether its bathroom breaks, get coffee, drink water, check my personal emails, answer my phone, stand up, sit down or shake my head. One time I experienced a TalkOverflowError, by recursively saying “I am about to talk” before actually talking. I have come to believe that Pair programming is just a catchy name for “Thinking through mouth”…
Dr.Pear: How do you feel about the quality of work?
Me: Its definitely improved. It has helped me identify minor bugs pretty early, that could have been a pain later. But there are times where I have completely rewritten my code at night, after an all day unsuccessful pairing.
Dr.Pear: Yeah, I have heard that happen. In general, do you feel you are productive?
Me: Sometimes yes, sometimes not. It does take longer time to achieve things initially.
Dr.Pear: Thats natural. Pairing is a trade-off between delivery-time and knowledge-spread. Its an insurance against concentrated knowledge. The preimum for that insurance is the early time investment. It also psychologically eliminates situations to unfairly blame others like ‘I cant touch that person’s code, I dont know what’s in there’. Eventually, its all about hitting the sweetspot of productivity. It does take some trial and error.
Me: Ok, I get that… But I have also developed some phobias recently, like mysophobia
Dr.Pear: These are side effects of this disorder. When you are pairing, you have to ensure that your personal hygiene is never compromised, especially if you are sharing the keyboard and mouse. Always clean your keyboards, do not eat while typing and wash your hands often. And don’t ever fall sick.
Me: Should I shower everyday?
Dr.Pear: I’m going to pretend I did not hear that…. now, this may sound unrelated, but nevertheless, how much time do you spend with your wife everyday?
Me: 1-2 hours?
Dr.Pear: …not including like helping with dishes, watching TV, you know.. just sit around..
Me: Just sit with her?
Dr.Pear: Yes, just quality talk time…face to face…husband to wife…
Me: 15 mts..?
Dr.Pear: So you spend 15 mts with your life-time companion everyday, but sit with your coworker for 8 hours straight talking face to face about every action you do?
Me: Apparently, Yes.
Dr.Pear: Hmm, recent scientific studies have proven that any amount of time spent with a coworker as a pair more than that you could with your own spouse is detrimental.
Me: And which study is this?
Dr.Pear: Its called the Pear’s Pair Limit. If (time-spent-with-pair > 1.5*time-spent-with-spouse), you end up in whats called Productivity Blackhole.
Me: I see… Does that mean I can pair only for 15 minutes a day?
Dr.Pear: Or you could spend 8 hours of quality talk time per day with your spouse…
Me: (blinking and awkward silence)
Dr.Pear: Got yaa! Ha ha ha! You developers always fall for that… Ok.. how about remote pairing? Like with people you have never met before face to face.
Me: Happens all the time… This one time, I ended up talking on headphone for over 10 hours. I ended up with a soar throat and my younger kid wondered why I was talking to the computer all day long.
Dr.Pear: Ha ha ha! Your kid is very observant, indeed.
Me: ???
Dr.Pear: Was just kidding. (murmurs) Get some humour, you techies… Anyways, so who else practices pairing in your office?
Me: All programmers, of course.
Dr.Pear: No, I mean pairing, not just pair programming…
Me: I thought pair programming is meant for programmers, Duh!
Dr.Pear: Er.. not exactly. Again scientific studies have shown that pairing is beneficial only if applied at all levels of an organizational structure. You know, like you can’t have one agile team and the rest of the organization is waterfall. At the programmers level, a risk of a bug usually costs much lesser than an issue that is not addressed at the architecture or management level.
Me: So like a Pair Architecting, Pair Managing?
Dr.Pear: More than that. “Pair Resourcing”. A programmer’s bug is lot more tangible, than a decision made at an architecture or management level. While a code defect can be fixed by some other programmer, “fixing” a wrong decision at the management level by another manager is usually very expensive. The higher the level of management, the costlier the fix.
Me: Ok, I get it now… An organization should always hire two people for the same position?
Dr.Pear: No. I meant more resposibility-spread in all levels. Imagine your reporting manager, who knows and appreciates all your hard work, quits. And your new manager is like Clark Gable from Gone with the Wind. A pair reporting manager would still know your work and share that with the new manager. The same technique goes all the way to CEOs.
Me: I see…and how is this measurable?
Dr.Pear: Pairing effectiveness can be measured quantitatively. You have Resources on the X-axis, Domain on the Y-axis. More vertical dots means one resource knows more stuff. More horizontal dots means many people know one stuff. Ideally connecting dots of edges will form a rectangle – everyone knows everything. Realistically it is a histogram. This is called Pear’s Knowledge-Responsibility-Spread graph. The closer the ratio of area of rectangle to area of histogram to 1.0, the better the organization’s base.
Me: Ok, I feel a lot better now. I think…
Dr.Pear: Sure, glad to help. Also here are a few business cards, please distribute in your office to your pairs and managers.
Me: (hesitantly) Er.. .Thanks!

Dr.Pear seriously types some notes about me on his laptop. I glean over him gently and looking at the screen and say “Er… doctor, I think you have a typo, you spelled my name incorrectly…”

Dr.Pear: What? Are you trying to pair with me now?

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