Juan Macias jmacias

From Out of the Tar Pit:

The key problem with testing is that a test (of any kind) that uses one particular set of inputs tells you nothing at all about the behaviour of the system or component when it is given a different set of inputs. The huge number of different possible inputs usually rules out the possibility of testing them all, hence the unavoidable concern with testing will always be — have you performed the right tests?. The only certain answer you will ever get to this question is an answer in the negative — when the system breaks.

This is a strong argument for some form of generative, simulation, or property-based testing.

Application specific host grouping in Riemann-dash

It is generally desirable to group all the hosts for a specific service into a single dashboard view. For example, all the web servers are in single view while all the database servers are in another view.

This is usually not an issue when you are sending custom metrics using Riemann client. However, there are cases where you are using something that you do not control how the metrics are being sent. i.e., Riemann-tools.

Since Riemann-tools scripts are application agnostic, in order for the dashboard view to group hosts, we must inject some application specific information into the tags field. Tags is a collection of arbitrary strings. In the case of Riemann-tools scripts you can pass in arbitrary strings on the command line.

riemann-health --host 127.0.0.1 --tag "prod" --tag "webserver"

Examples of RESTful API calls for E-commerce platforms

These examples are type 3 RESTful API requests and responses. The JSON-HAL specification is used to implement HATEOAS.

Some of the examples are based on my work as architect of the RESTful API at http://www.hautelook.com. All proprietary information has been removed.

Relevant links

JSON-HAL specification: http://stateless.co/hal_specification.html#media_type_identifiers
JSON linking with HAL: http://blog.stateless.co/post/13296666138/json-linking-with-hal

Links for essays ref'd in http://blog.fogus.me/2009/03/11/seven-books/

Imagine you inherit a significantly large Java codebase. The code is very poor. What are the libraries and methods that might help you regain sanity?

To start:

Systems Thinking

"The Fifth Discipline", by Peter Senge (http://amzn.to/H7R4fp)
"Lean Thinking", by James Womack (http://amzn.to/H7R9zK)
"The Logic of Failure", by Dietrich Dorner (http://amzn.to/HyheLM)
"Drift Into Failure", by Sidney Dekker (http://amzn.to/HpB8Fe)

Software Architecture & Methods

"Documenting Software Architecture", by Paul Clements (http://amzn.to/H7RtOP)

	(ns example.errors)

	(defn clean-address [params]
	"Ensure (params :address) is present"
	(if (empty? (params :address))
	[nil "Please enter your address"]
	[params nil]))

	(defn clean-email [params]
	"Ensure (params :email) matches @.*"

	;;;; Super top secret talk stuff nobody should ever see. Shhh.

	(in-ns 'user)

	(defmacro bench [& body]
	`((re-find #"\"(.*)\"" (with-out-str (time (do ~@body)))) 1))

	ns

	(require 'clojure.walk)

	// Not composable function: DON'T DO THIS!
	function complexProcess() {
	var a = getComponent(globalState),
	b = subprocessOne(a),
	c = subProcessTwo(a, b),
	d = subProcessThree(a, b, c);
	resetGlobalState(d);
	}

	// Composable Funtion

	(ns rxjava-datomic.query
	(:require [datomic.api :as d])
	(:use [clojure.repl :only [pst]])
	(:import [rx Observable]
	datomic.Peer))

	(defn query [qry & inputs]
	(Observable/toObservable
	(Peer/q qry (object-array inputs))))