Synopsis

Building a Small Bank with Clojure

Created: Thu 18 Oct 03:34:12 -03 2018 Application Version: 0.0.1-alpha

An article was published explaining:

• https://www.javacodegeeks.com/2019/02/small-bank-application-clojure.html
• https://dzone.com/articles/building-a-small-bank-with-clojure

This file is intended to demonstrate the execution and testing of the Duck application. Application created for studies and tests with clojure language.

Provided Mechanisms

It must comprise a HTTP Server with two endpoints:

One to insert a new monetary transaction, money in or out, for a given user; One to return a user's current balance.

• Receive a command and return the response;
• Manage multiple concurrent connections using thread.
• It must not be possible to withdraw money for a given user when they don't have enough balance;
• You should take concurrency issues into consideration;
• It must be executable in Unix, Linux & MacOS machines;

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CONTENTS:

    (sec-01) APPLICATION EXECUTION PLATFORM
    (sec-02) INSTALLING THE REQUERIED PACKAGES
    (sec-03) RUNNING THE DUCK APPLICATION
    (sec-04) DETAILS OF EACH APPLICATION FEATURE

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(sec-01) APPLICATION EXECUTION PLATFORM

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The requirements of the application is to run on Linux and Mac/OS machines. It was not possible to test Mac/OS because there was no machine available with this system.

The application was developed using the FreeBSD-11 operating system and was tested on a virtual machine using Linux/Ubuntu-18.

The application was developed using Clojure the versions of the packages are:

• clojure-1.9.0.381 - Dynamic programming language for the JVM;
• leiningen-2.8.1 - Automate Clojure projects.

Main Clojure libraries/plugins used:

• Compojure - Is a small routing library for Ring that allows web applications to be composed of small, independent parts; (https://github.com/weavejester/compojure)

• DataJSON - JSON parser/generator to/from Clojure data structures; (https://github.com/clojure/data.json)

• Ring-Mock - Is a library for creating Ring request maps for testing purposes; (https://github.com/ring-clojure/ring-mock)

• Clj-Time - A date and time library for Clojure, wrapping the Joda Time library; (https://github.com/clj-time/clj-time)

• Lein-Midje - This plugin runs both Midje and clojure.test tests; (https://github.com/marick/lein-midje)

• Codox - A tool for generating API documentation from Clojure or ClojureScript source code; (https://github.com/weavejester/codox)

• Cljfmt - Is a tool for formatting Clojure code. (https://github.com/weavejester/cljfmt)

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(sec-02) INSTALLING THE REQUERIED PACKAGES

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To install the required packages see the topics of each system.

• FREEBSD-11

   pkg install clojure leiningen
   pkg install bash

• LINUX/UBUNTU-18 (https://lispcast.com/clojure-ubuntu/)

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(sec-03) RUNNING THE MCDUCK APPLICATION

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Important: Version JDK used to build this project is jdk1.8.0.

To run the project and perform the tests please follow the steps below:

1. To run the project please unzip the file:

   tar xfv duck-0.0.1-alpha.tar.bz2

2. To run and install the required packages please run:

   cd duck-0.0.1-alpha
   ./launch-app

3. At another terminal run the unit tests:

   lein midje

4. To take a stress test perform:

   ./launch-curl

5. Checking the formatting of the code:

   lein cljfmt check

6. Generating HTML documentation:

   lein codox

In the case of HTML documentation it is available by default in the folder of the project itself located at: (target/doc/index.html)

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(sec-04) DETAILS OF EACH APPLICATION FEATURE

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To make the tests more detailed is used the command curl in the terminal it is possible to use the browser as well.

ATTENTION:

o In order not to interfere with the previous tests please stop the application server and start again.

o It is important to put the date of the day you are doing the transaction, field (date) in pattern DD/MM/YYYY.

The idea is to do a step-by-step for understanding, copy and paste the commands in the terminal.

1. Entering a new account with the starting balance of (150.90). The API returns a message of success: Successful transaction.

curl -H "Content-Type: application/json" -X POST -d '{"amount":150.90, "date":"18/10/2018", "account":1112, "description":"Credit 1"}' http://127.0.0.1:3000/transaction/add

API-RESP: Successful transaction

2. Checking available balance for account (1112):

curl -H "Content-Type: application/json" -X GET http://127.0.0.1:3000/account/1112/balance

API-RESP: {"account":1112,"date":"2018-10-18T03:05:55.077-03:00","balance":150.9}

3. Cash out from account 1112, Eg: pulling out the (50) value from the account:

curl -H "Content-Type: application/json" -X POST -d '{"amount":-50, "date":"18/10/2018", "account":1112, "description":"Debit 1"}' http://127.0.0.1:3000/transaction/rm

API-RESP: Successful transaction

4. Check again your account balance, step 2:

curl -H "Content-Type: application/json" -X GET http://127.0.0.1:3000/account/1112/balance

API-REST: {"account":1112,"date":"2018-10-18T03:11:54.554-03:00","balance":100.9}