WORK ORDER PRIORITY QUEUE WEB SERVICES

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Problem Statement

  Create a web service that accepts work orders and provides a prioritized list to work.    

For an alternate approach based on Ticker ( Ticker is like a pendulum's movement in a clock. Appropriately, one cycle of the event loop is called a tick.), click here.

• WorkOrder REST API
  • Getting Started
  • Pre Dev Analysis
  • API Contract
  • License

This project is a Restful API for creating work order queue for Service Desk employee. The work order can be of four types normal, priority, VIP, and management override. Different request types have their own implementation for calculating the rank. The priority queue is sorted from highest ranked to lowest ranked requester ID.

GETTING STARTED

This application is a written in java using Spring Boot and built using Maven.

Prerequisites

• Git
• JDK 8 or later
• Maven 3.0 or later

Quick Start

To test the application, just follow the two simple steps mentioned below:

1. Download the fat jar of this application from bin folder. Now to start the application server, open command prompt and run the downloaded jar file,

        java -jar workorder-1.0.0.one-jar

2. Once the server gets started, download the postman collection form postman folder of the project. Import the collection in Postman client and you will be all set to play around with the API.

Clone

To get started you can simply clone this repository using git:

git clone https://github.com/Govind-jha/springboot-work-order-priority-queue.git
cd springboot-work-order-priority-queue

Build an executable JAR

You can run the application from the command line using

        mvn spring-boot:run

Or you can build a single executable JAR file that contains all the necessary dependencies, classes, and resources with

        mvn clean package

Then you can run the JAR file with

        java -jar target/*.jar

Test

Download the postman collection form postman folder. Import the collection in Postman client for smoke testing.

You can test these Micro Services using any tool or language that allows you to make a HTTP request. For example, removing an order using CURL:

curl -X DELETE \
  http://localhost:8080/workorder/remove/20 \
  -H 'Cache-Control: no-cache' 

Creating a work order in the queue using require module in Node.js,

var request = require("request");

var options = { 
    method: 'POST',
      url: 'http://localhost:8080/workorder/addOrder',
      headers: 
       { 
            'Cache-Control': 'no-cache',
            'Content-Type': 'application/json' 
        },
      body: { requesterId: 20, timeOfRequest: 5000000000 },
      json: true 
};

request(options, function (error, response, body) {
  if (error) throw new Error(error);

  console.log(body);
});

PRE DEV ANALYSIS

Object Model

PriorityQueue<WorkOrder>[ 
    WorkOrder{
        requestorID, 
        requestType,
        requestTimestamp,
        requestDate
    }, ...   
]

Request Type Calculation

There are 4 classes of IDs, normal, priority, VIP, and management override. You can determine the class of the ID using the following method,  

Request Type	Condition
NORMAL	(requestorID % 3 != 0 && requestorID % 5 != 0)
PRIORITY	requestorID % 3 == 0
VIP	requestorID % 5 == 0
MANAGEMENT_OVERRIDE	(requestorID % 3 == 0 && requestorID % 5 == 0)

Rank Calculation Formula

The table below lists the formulas for calculating the rank of different request types,  

Request Type	Ranking Function
NORMAL	secondsSpentInQueue
PRIORITY	max( 3 , secondsSpentInQueue * log(secondsSpentInQueue) )
VIP	max( 4 , 2 * secondsSpentInQueue * log(secondsSpentInQueue) )
MANAGEMENT_OVERRIDE	max(NORMAL.maxPriority(), PRIORITY.maxPriority(), VIP.maxPriority()) + secondsSpentInQueue

API Contract

The WorkOrder Api implements the requirement/rules described in the previous section. It is used to create a prioritized work order queue (a Priority Queue) for service request desk employee. It provides fetures like adding or removing an order from the queue based on priority, getting a sorted list of order etc.

Response Code And Headers

If response status code is 204 NO CONTENT or 205 RESET CONTENT, the response will contain header x-app-diagnostic. HTTP status 205 RESET CONTENT means server successfully processed the request, but is not returning any content. Unlike a 204 NO CONTENT response, this response requires that the requester reset the document view (as the content might have changed).

Response header x-app-diagnostic will contain the cause of no content in the response body.

Response Codes

Status Code	Message
200	Success
201	Content Created
204	No Content
205	Reset Content
404	Not Found
405	Method Not Allowed
415	Usupported Media Type

• Check the requests content type if you get HTTP Status 415.
• Check the requests Method(GET, POST, DELETE) if you get HTTP Status 405.

API Operation

The Application will start on port 8080, you can change this port configuration in application.properties file of the project.

Base Resource	Description
/workorder	provides endpoints for performing create, read and delete operations on work order queue.

API Operation	Description	Allowed Methods
/addOrder	An endpoint for adding a ID to queue (enqueue). This endpoint should accept two parameters, the ID to enqueue(requesterId) and the time at which the ID was added to the queue(timeOfRequest).	POST
/getPosition/{requesterId}	An endpoint to get the position of a specific ID in the queue. This endpoint should accept one parameter, the ID to get the position of. It should return the position of the ID in the queue indexed from 0.	GET
/getOrderList	An endpoint for getting the list of IDs in the queue. This endpoint should return a list of IDs sorted from highest ranked to lowest.	GET
/remove/{requesterId}	An endpoint for removing a specific ID from the queue. This endpoint should accept a single parameter, the ID to remove.	DELETE
/removeNextOrder	An endpoint for getting the top ID from the queue and removing it (dequeue). This endpoint should return the highest ranked ID and the time it was entered into the queue.	GET
/avgWaitTime/{currentTimeInMillis}	An endpoint to get the average wait time. This endpoint should accept a single parameter, the current time, and should return the average (mean) number of seconds that each ID has been waiting in the queue.	GET

 

License

The package is Open Source Software released under the License. It's developed by Govind Jha.