# Sparklines Example

This example is inspired by Joe Gregorio's Sparkline Generator Web Application. For more about the concept of sparklines read here.

## Contents

The example consists of one web resource implemented by the following:

`org.glassfish.jersey.examples.sparklines.SparklinesResource`
  This Java class returns the a PNG image of a sparkline calculated for a given set of query parameters.

The example makes use of classes to parse query parameters, a message body writer to write an image in the PNG format, and makes use of entity tags and performs precondition checking to support not modified responses.

The mapping of the URI path space is presented in the following table:

URI path | Resource class | HTTP methods | Description
--- | --- | --- | ---
discrete | SparklinesResource | GET | Plot a sparkline as discrete vertical bars, one per data value.
smooth | SparklinesResource | GET | Plot a sparkline as continuous line.

For either URI path the following query parameters can be declared:

Query parameter | Default Value | Description
--- | --- | ---
d |  | A comma separated list of integer values that represents the input data to plot as a sparkline.
limits | 0,100 | The valid range of the input data in "d".

The "smooth" URI path can have following query parameters:

Query parameter | Default Value | Description
--- | --- | ---
min-m | true | If true then a marker is placed at the smallest value in the input data.
max-m | true | If true then a marker is placed at the largest value in the input data.
last-m | true | If true then a marker is placed at the last value in the input data.
min-color | blue | The colour of the marker placed at the smallest value in the input data
max-color | green | The colour of the marker placed at the largest value in the input data.
last-color | red | The colour of the marker placed at the last value in the input data.
step | 2 | The horizontal distance, in pixels, between each plot of a data value.

The "discrete" URI path can have following query parameters:

Query parameter | Default Value | Description
--- | --- | ---
width | 2 | The width, in pixels, of each plot of a virtual bar for each data value.
upper | 50 | Data values >= upper will be coloured in "upper-color" otherwse data values will be colured in "lower-color"
upper-color | red | The colour for data values >= "upper"
lower-color | gray | The colour for data values < upper

## Running the Example

Run the example as follows:

run

> `mvn compile exec:java`

From a web browser, visit:

> `http://localhost:9998/sparklines/discrete?d=88,84,82,92,82,86,66,82,44,64,66,88,96,80,24,26,14,0,0,26,8,6,6,24,52,66,36,6,10,14,30`

and manipulate the URI manually to adjust the result image.

You can also use the example's web frontend at:

> `http://localhost:9998/sparklines`

to see the basic functionality.