thezelus/dogTracker

##dogTracker##

A web application to visualize (near real-time) simulated motion of trackers implanted in dog collars (and get my feet wet with Spring).

###Installation instructions###

Clone the repo git clone https://github.com/thezelus/dogTracker.git
In the project directory run mvn -U clean install
Under /trackingServer/target and /viewServer/target corresponding war files can be found
Deploy those files in tomcat webapps directory to run the project
Properties files can be found in expanded war directories under classpath directory

(An alternative way is to directly download release files from releases page and then follow last two steps of installation instructions.)

Default trackingServer.properties (/webapps/trackingServer/WEB-INF/classes)

xLower = 10
xUpper = 780
yLower = 10
yUpper = 580
rfidCount = 100
dataUpdatePeriod = 2000

Where

(xLower, xUpper), (yLower, yUpper) define the range of x and y values for a position
rfidCount defines number of trackers to be generated for simulation
dataUpdatePeriod defines the time interval in millisecond for the change in data values to simulate motion

Default viewServer.properties (/webapps/viewServer/WEB-INF/classes)

trackingServer.BaseUrl=http://localhost:8080/trackingServer
trackingServer.StatusPath=/status
trackingServer.IdPath=/data/id
trackingServer.AllIdsPath=/data/ids
outboundRequestIntervalInMilliseconds=2000

Where outboundRequestIntervalInMilliseconds defines the time interval between the request sent out to trackingServer for fresh data.

###API Documentation###

Tracking server API has following end points

Note: All GET calls to this API require Accept header with value application/json. This can be easily accomplished using some REST client like Postman

####Status####

Returns server status (both for trackingServer and viewServer)

Method: GET
URL: /status
Header: Accept with value application/json
Response: JSON array of id values

{
    "status": "Server is running",
    "current": "2015-02-10T03:27:26.656Z"
}

####Get Ids####

Returns all the ids for the trackers that are present in the datasource in a JSON response format

Method: GET
URL: /data/ids
Header: Accept with value application/json
Response: JSON array of id values

[
    "id44",
    "id25",
    "id19",
    "id77",
    "id64",
    "id38"
]

####Get tracker data for id####

Returns data associated with the given tracker id in a JSON format, otherwise returns error response

Method: GET
URL: /data/id/{id}
Header: Accept with value application/json
Response:

---> For valid id:

{
    "id": "id2",
    "xCoordinate": 500,
    "yCoordinate": 79,
    "heartRate": 135,
    "bodyTemperatureInFahrenheit": 98.69133
}

---> For invalid id (that might have been removed): Response status is 410 Gone

{
    "code": "INVALID_KEY_VALUE",
    "message": "Value associated with this key is null",
    "description": ""
}

###View Server Canvas###

View server has a dashboard that can be used to visualize the simulated motion of trackers. This can be found at /viewServer/canvas

The data on this view updates every 2500 millisecond

Screenshots of this page can be seen below -

###Design Decisions (for current release)###

XML based deployment descriptors for supporting older versions of Servlet
Configurable properties for web apps (trackingServer & viewServer) can be found in classpath after the war files are deployed (/webapps/trackingServer/WEB-INF/classes)
Custom error responses when key is absent to differentiate between when key is absent and when the remote server is down
Fault tolerance (https://github.com/Netflix/SimianArmy/wiki/Chaos-Monkey): data in the viewServer is preserved in its last state if for some reason trackingServer goes down
In-memory data source is being used to minimize dependencies
View server uses /liveData end point to get latest JSON array, this will help with future implementations for other clients or API extension

###Assumptions###

RFId tracker receives coordinates in form of (x,y) where (0,0) is the top left corner of the canvas
Default range for body temperature and heart rate are assumed
To simulate motion and change in vitals, data is modified internally (in the trackingServer) using a separate thread
Data simulation generates random x-y coordinates and vitals within the given range
Data in client’s browser updates every 2500 milliseconds
Canvas default size is 800px x 600px

###Todo list###

Refactor, add more tests (both unit and integration) - top priority
Use Redis as an in-memory data store
Use Protocol buffers for model generation
Re-engineer frontend to make it more responsive
Increase familiarity with Spring annotations
Replace random motion model with pedestrian simulation model for generation of simulation data

###High level application architecture###

Note - Current release is no where close to the quality of code that I want, this project is a learning exercise about how to setup and use spring and hence needs heavy refactoring.

thezelus / dogTracker

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