platform-coding-challenge

Commonwealth Interview - Platform Coding Challenge

Overview

This project implements a solution to the Commonwealth Coding Challenge as of February 2016. For details about the said challenge please refer to the document "Platform Engineering - Coding Challenge.pdf".

In summary the problem requests to write a program, in a programming language of choice, to read in a list of URLs from a file and then perform a GET request to each website to measure the request latency outputting it in a JSON file.

Implementation

The solution delivered here is a Java project implemented as a multi-module Maven project containing the following modules:

• platform.coding.challenge. Top-level project. Used to trigger the multi-module build.
• latency-measurement-schema. Generates application model classes from an XML schema.
• latency-measurement-service. Implements the business logic to calculate remote network latency.
• latency-measurement-endpoint. Exposes the above business functionality as a REST web service.
• latency-measurement-cli. Implements a standalone command-line utility to read a list of URLs from a file, calculate the latency for each entry and then output the results to a file using JSON format.

Building the solution

In order to build the program, the following is required

• Java 8 JDK
• Maven 3.x
• A working internet connection (to download required library dependencies)

In order to start a project build clone this project to your development machine then at the top-level directory type: $ mvn clean package

After a few minutes and if everything goes well you will se the following output:

[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] Latency Measurement Builder ....................... SUCCESS [1.103s]
[INFO] Latency Measurement Schema ........................ SUCCESS [3.271s]
[INFO] Latency Measurement Business Service .............. SUCCESS [4.033s]
[INFO] Latency Measurement REST endpoint ................. SUCCESS [8.624s]
[INFO] Latency Measurement CLI ........................... SUCCESS [0.293s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 17.464s
[INFO] Finished at: Sun Feb 07 02:34:52 EST 2016
[INFO] Final Memory: 43M/254M
[INFO] ------------------------------------------------------------------------

Running the program

After building the application you can run the latency measurement command-line utility by performing the following steps:

1. At the top-level directory run the following command to start the embedded web server which launches the application backend:

# you must have successfully run a maven build in order to start the web server
platform-coding-challenge $ ./latency-measurement-endpoint/run.sh

You can check if the application backend has started successfully by opening the following URL in your browser. This will launch the Swagger UI front-end which can be used to test the REST API in standalone mode.

http://localhost:8080/latency-measurement-endpoint/swagger-ui/index.html

2. At the top-level directory run the following command to start the embedded web server which launches the client application:

platform-coding-challenge $ ./latency-measurement-cli/run.sh

If the program has run successfully you should see something resembling the following output on your console:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.2.6.RELEASE)

2016-02-07 15:59:11.199  INFO 59293 --- [           main] .m.c.LatencyMeasurementClientApplication : Starting LatencyMeasurementClientApplication on Alexs-MacBook-Air.local with PID 59293 (/Users/alex/Workspaces/GitHub/platform-coding-challenge/latency-measurement-cli/target/classes started by alex in /Users/alex/Workspaces/GitHub/platform-coding-challenge/latency-measurement-cli)
2016-02-07 15:59:11.243  INFO 59293 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@692a79e4: startup date [Sun Feb 07 15:59:11 AEDT 2016]; root of context hierarchy
2016-02-07 15:59:12.004  INFO 59293 --- [           main] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2016-02-07 15:59:12.744  INFO 59293 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2016-02-07 15:59:12.753  INFO 59293 --- [           main] .l.m.c.s.i.LatencyMeasurementServiceImpl : Performing network latency tests using input file: URL.txt
2016-02-07 15:59:18.797  INFO 59293 --- [           main] .m.c.LatencyMeasurementClientApplication : LatencyMeasurementService returned {
  "responses" : [ {
    "url" : "http://www.xkcd.com/443?foo=bar",
    "latency_Ms" : 183.0,
    "count" : 3,
    "timestamp" : "2016-02-07T04:59:15.599Z",
    "min" : 167,
    "max" : 1975,
    "range" : 1808,
    "average" : 775.0,
    "median" : 183.0
  }, {
    "url" : "https://twitter.com",
    "latency_Ms" : 1005.0,
    "count" : 3,
    "timestamp" : "2016-02-07T04:59:16.849Z",
    "min" : 977,
    "max" : 1595,
    "range" : 618,
    "average" : 1192.3333333333333,
    "median" : 1005.0
  }, {
    "url" : "https://www.facebook.com:443",
    "latency_Ms" : 1369.0,
    "count" : 3,
    "timestamp" : "2016-02-07T04:59:17.448Z",
    "min" : 711,
    "max" : 1957,
    "range" : 1246,
    "average" : 1345.6666666666667,
    "median" : 1369.0
  }, {
    "url" : "https://www.google.com",
    "latency_Ms" : 1356.0,
    "count" : 3,
    "timestamp" : "2016-02-07T04:59:18.641Z",
    "min" : 1338,
    "max" : 2537,
    "range" : 1199,
    "average" : 1743.6666666666667,
    "median" : 1356.0
  } ]
}
2016-02-07 15:59:18.800  INFO 59293 --- [           main] .m.c.LatencyMeasurementClientApplication : Latency measurement results have been saved to file '/Users/alex/Workspaces/GitHub/platform-coding-challenge/latency-measurement-cli/latency.json'
2016-02-07 15:59:18.801  INFO 59293 --- [           main] .m.c.LatencyMeasurementClientApplication : Started LatencyMeasurementClientApplication in 7.807 seconds (JVM running for 15.674)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 14.270s
[INFO] Finished at: Sun Feb 07 15:59:18 AEDT 2016
[INFO] Final Memory: 41M/350M
[INFO] ------------------------------------------------------------------------

Additional Notes

• If you want to change the port on which the web server is run you will need to modify the run script (run.sh) located in the latency-measurement-endpoint subfolder. Accordingly, you also need to modify the web service URL which is part of the CLI configuration within latency-measurement-cli/application.properties.

• By default, the CLI program uses a file called URL.txt as input and it creates or writes to an output file called latency.json. If you wish to change either of those parameters you can do so by passing the following parameters to the client run script (run.sh):

$ ./latency-measurement-cli/run.sh --input="path_to_input_file" --output="path_to_output_file"