realTimeDeparture

A service that gives real-time departure time for public transportation

1. Problem Statement

Create a service that gives real-time departure time for public transportation (use freely available public API). The app should geolocalize the user.

2. Solution

Rest-based web service that provides the real-time departure time at a user-provided stop. This service utilizes the Nextbus API.

3. Build & Run Instructions

Obtain repository from GitHub

$ git clone https://github.com/tendaitt/realTimeDeparture.git
Go into project directory

$ cd realTimeDeparture/
Build the project using gradle

$ ./gradlew build -x test
To run locally, execute the following command

$ ./gradlew bootRun
Application should be live at http://localhost:8080/

PS:The page shown is a AngularJS page showing the result for a hard-coded stop.
To run in Eclipse omit the bootRun step and continue on to the following subsection.

Importing into Eclipse

Generate eclipse dependencies

$./gradlew eclipse
Open Eclipse.Go to File->Import
Under Gradle, select Existing Gradle Project
Complete the steps in the wizard and Finish
You will now be able to start the project in Eclipse by running the src/main/java/com/assessment/departure/DepartureTimeApplication.java class.
Application should be live at http://localhost:8080/

4. Hosted Location

Application is hosted on Heroku at the following location: https://ancient-chamber-53270.herokuapp.com/getDepartureTime?stopTag=5205
The GitHub repository is at the following location: https://github.com/tendaitt/realTimeDeparture

5. Using the application

Once the application is running or you go to the hosted location, you can use it by adding a <stopTag> value in the URL as illustrated below.

URL structure

http://<host>/getDepartureTime?stopTag=<stopTag>

Sample URLs

Running application locally: http://localhost:8080/getDepartureTime?stopTag=4448
Running application on Heroku: https://ancient-chamber-53270.herokuapp.com/getDepartureTime?stopTag=4448

Sample Response

{"stopTitle":"Duboce Ave & Church St","direction":"Inbound to Caltrain/Ball Park","waitTime":2}

Fields:

stopTitle: the name of the stop.
direction: the direction of the bus.
waitTime: the time, in minutes, until the next bus arrives.

PS If the direction and waitTime are empty, there are no available predictions for departure at that time.

Sample `<stopTag>`


7217	4447	4448
5731	5206	3913
6995	3912	5193

6. Technical Decisions

Missing functionality

Application does not geolocalize the user to provide the result. Instead it takes a user input for a stop and returns the wait time. This feature was not implemented partly because the Nextbus API does not have a prediction request that takes in a Longitude and Latitude.

Additional Feature

Instead of merely returning the wait time, the application also retrieves the stop title and direction of the bus.

Architecture

The decision to implement the application as a REST-based web service was largely due to familiarity with the technology.
The application also models a Service Oriented Architecture. This ensures that we can easily replace components such as the Nextbus API with minimal code changes.

7. Trade-offs and Improvements

Trade-offs

Since there is no geolocalization of the user, an alternative approach to retrieving the wait time had to be used. The application uses a prediction API call, from Nextbus, that takes in a <route tag>, <agency tag> and <stop tag>. The route and agency are hard-coded while the user provides the stop tag.

TODOs

Add a fully functioning UI for the application.
Add integration testing and increase the number of unit tests for the application.
Implement geolocation functionality.
Handle the scenario where the Nextbus API is down or it does not return the expected value.

tendaitt/realTimeDeparture