Define Functions

Prerequisites: You have already

1. created a Test

2. uploaded some data

Using Functions in Horreum is a feature that provides a great deal of bespoke functionality to Horreum that is under the control of a user. The ability to use a Function written in JavaScript.

These Functions can be categorized as:

• Selector (filter) - used for applying conditions on input data to return output data
• Transformation - used for changing the data model
• Combination - used for computing a scalar value
• Rendering - reformatting the presentation of the data

When using Horreum you will find Functions used in these Horreum objects:

Making use of Horreum Functions

JavaScript ECMAScript 2023 specification is available throughout Horreum Functions.

Example Filtering Function

These Functions rely on a condition evaluation to return a boolean value. The following will filter based on the individual Label Extractor only having the value 72.

value => value === 72

Example Transformation Functions

Transformation Functions rely on a returned value that is an Object, Array or scalar value. This Transformation Function relies on 12 Extractors setup on the Schema Label. Each Extractor configured to obtain an Array of data items (except buildId and buildUrl).

Input JSON

{
  "runtimeName": "spring-native",
  "rssStartup": 55,
  "maxRss": 15,
  "avBuildTime": 1234,
  "avTimeToFirstRequest": 5,
  "avThroughput": 25,
  "rssFirstRequest": 5000,
  "maxThroughputDensity": 15,
  "buildId": "x512",
  "buildUrl": "http://acme.com",
  "quarkusVersion": "0.1",
  "springVersion": "3.0"
}

This Transformation Function uses the map JavaScript function to modify property names, the number of JSON properties and values. In the transformation runtime and buildType are created from the filtered runtimeName property. The version property is conditionally derived from runtimeName depending on the presence of the text spring.

({runtimeName, rssStartup, maxRss, avBuildTime, avTimeToFirstRequest, avThroughput, rssFirstRequest, maxThroughputDensity, buildId, buildUrl, quarkusVersion, springVersion}) => {
    var map = runtimeName.map((name, i) => ({
        runtime: name.split('-')[0],
        buildType: name.split('-')[1],
        rssStartup: rssStartup[i],
        maxRss: maxRss[i],
        avBuildTime: avBuildTime[i],
        avTimeToFirstRequest: avTimeToFirstRequest[i],
        avThroughput: avThroughput[i],
        rssFirstRequest: rssFirstRequest[i],
        maxThroughputDensity: maxThroughputDensity[i],
        buildId: buildId,
        buildUrl: buildUrl,
        version: ((name.split('-')[0].substring(0, 6) == 'spring' ) ? springVersion: quarkusVersion )
    }))
    return map;
}

Output JSON

{
  "runtime": "spring",
  "buildType": "native",
  "rssStartup": 55,
  "maxRss": 15,
  "avBuildTime": 1234,
  "avTimeToFirstRequest": 5,
  "avThroughput": 25,
  "rssFirstRequest": 5000,
  "maxThroughputDensity": 15,
  "buildId": "x512",
  "buildUrl": "http://acme.com",
  "version": "3.0"
}

Example Combination Functions

Combination Functions rely on a returned value that is an Object, Array or scalar value.

Input JSON

[5,10,15,20,10]

This Function will conditionally reduce an array of values unless there is only a single value of type number.

value => typeof value === "number" ? value : value.reduce((a, b) => Math.max(a, b))

Output JSON

20

The following example returns a scalar Float value.

Input JSON

{
  "duration": "62.5",
  "requests": "50"
}

This Function will create a value of the amount of time per request with the exponent rounded to 2 figures.

value => (value.duration / value.requests).toFixed(2)

Output JSON

1.25

Example Rendering Functions

A Rendering Function will change the presentation or add metadata for rendering in the UI.

Input JSON

Hello World

This Rendering Function adds HTML markup and sets the color of the span text.

value => '<span style="color: Tomato";>' + value + '</span>'

Output text

<span style="color: Tomato;">Hello World</span>

Troubleshooting Functions.

See the section dedicated to Troubleshooting Functions.