Real-time Gauges

The thermometer gauge is a real-time chart, which can continuously request new data from the server and display the same, without involving any page refreshes. The chart initializes itself, loads new data periodically, and automatically updates to reflect the current state of data. There are two different ways to update the thermometer gauge; one method directly polls data from the server while the other retrieves data using JavaScript API methods.

In this section, you will be shown how you can,

● Configure real-time updates using JavaScript API

● Configure real-time updates using server-side script

● Stop/restart updates

● Configure real-time events

● Troubleshoot real-time gauges

Configuring Real-time Updates Using JavaScript API

Real-time Data Format

The data provider page on the server’s end, when invoked by the thermometer gauge, will output the new data in the real-time data format.

The real-time data format for gauges depends on:

● the value to be passed

● whether you are using the message logger for the gauge

● the use of commands for the gauge - like stop update etc.

In the simplest form, if you’re looking to update the thermometer gauge, you need to output the data in following format:

&value=-5

Here, the output is a single value, -5. So, when the gauge will read this value, it will update the chart by setting its value to -5 (if a data range is provided by the gauge, the value will first be checked to verify if it falls within the defined range).

A thermometer gauge configured for real-time updates using JavaScript API looks like this:

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Given below is a brief description of the JavaScript API used to configure real-time updates:

Function Name	Parameter	Description
`feedData(strData)`	strData	This method is used to feed real-time data to the gauge using JavaScript. The data has to be in the same format as provided by the real-time data provider page.
`getData()`	None	This method is used to return the data currently being shown by the gauge.
`setData(value)`	value	This method is used to set the data value for the gauge. The value should be within the limits of the gauge.

The data structure needed to configure real-time updates using JavaScript API is given below:

JSON
XML

{ "chart": { "caption": "Temperature Monitor", "subcaption": " Central cold store", "lowerLimit": "-10", "upperLimit": "0", "numberSuffix": "°C", "decimals": "1", "showhovereffect": "1", "thmFillColor": "#008ee4", "showGaugeBorder": "1", "gaugeBorderColor": "#008ee4", "gaugeBorderThickness": "2", "gaugeBorderAlpha": "30", "thmOriginX": "100", "theme": "fint" }, "value": "-6" }

{
    "chart": {
        "caption": "Temperature Monitor",
        "subcaption": " Central cold store",
        "lowerLimit": "-10",
        "upperLimit": "0",
        "numberSuffix": "°C",
        "decimals": "1",
        "showhovereffect": "1",
        "thmFillColor": "#008ee4",
        "showGaugeBorder": "1",
        "gaugeBorderColor": "#008ee4",
        "gaugeBorderThickness": "2",
        "gaugeBorderAlpha": "30",
        "thmOriginX": "100",
        "theme": "fint"
    },
    "value": "-6"
}

Configuring Real-time Updates Using Server-side Script

A thermometer gauge configured for real-time updates using server-side script looks like this:

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Given below is a brief description of the attributes needed to configure real-time updates from the server:

Attribute Name	Description
`dataStreamURL`	This parameter sets the path of the page which is supposed to relay real-time data to the chart. If you have special characters as a part of the data stream URL, like ? or &, you will have to URL Encode the entire `dataStreamURL`. This page needs to be on the same sub-domain on which the chart is hosted and invoked from. Otherwise, security will restrict it from accessing the data and hence the real-time feature won’t work. Example: `dataStreamURL='liveQuote.aspx?name=xyz'`
`refreshInterval`	For this parameter, we can specify the number of seconds after which the chart will look for new data. This process will happen continuously - i.e., if we specify 5 seconds here, the chart will look for new data after every 5 seconds.
`dataStamp`	Constantly changing data stamp that can be added to the real-time data URL, so as to maintain a state. For more information, read the Adding Data Stamp article.

The data structure needed to configure real-time updates using server-side script is given below:

JSON
XML

{
    "chart": {
        "caption": "Temperature Monitor",
        "subcaption": " Central cold store",
        "lowerLimit": "-10",
        "upperLimit": "0",
        "numberSuffix": "°C",
        "decimals": "1",
        "showhovereffect": "1",
        "thmFillColor": "#008ee4",
        "showGaugeBorder": "1",
        "gaugeBorderColor": "#008ee4",
        "gaugeBorderThickness": "2",
        "gaugeBorderAlpha": "30",
        "thmOriginX": "100",
        "dataStreamURL": "../../../resources/php/gauge-and-widgets-guide-thermometer-gauge-real-time-gauges-php-1.php",
        "refreshInterval": "5",
        "theme": "fint"
    },
    "value": "-6"
}

Stopping/Restarting Updates

A thermometer gauge configured to stop and restart receiving real-time updates looks like this:

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Given below is a brief description of the JavaScript API used to stop and restart receiving real-time updates:

Function Name	Parameter	Description
`stopUpdate()`	`None`	This method stops the chart from self-updating.
`restartUpdate()`	`None`	If you’ve stopped the real-time update of the chart, you can resume the update using this method.

The data structure needed to stop and restart receiving real-time updates is given below:

JSON
XML

{
    "chart": {
        "caption": "Temperature Monitor",
        "subcaption": " Central cold store",
        "lowerLimit": "-10",
        "upperLimit": "0",
        "numberSuffix": "°C",
        "decimals": "1",
        "showhovereffect": "1",
        "thmFillColor": "#008ee4",
        "showGaugeBorder": "1",
        "gaugeBorderColor": "#008ee4",
        "gaugeBorderThickness": "2",
        "gaugeBorderAlpha": "30",
        "thmOriginX": "100",
        "dataStreamURL": "../../../resources/php/gauge-and-widgets-guide-thermometer-gauge-real-time-gauges-php-2.php",
        "refreshInterval": "5",
        "theme": "fint"
    },
    "value": "-6"
}

Configuring Real-time Events

FusionCharts Suite XT introduces two events, realTimeUpdateComplete and realTimeUpdateError, to track real-time updates on gauges.

A real-time thermometer gauge configured to listen to the realTimeUpdateComplete event looks like this:

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Given below is a brief description of the realTimeUpdateComplete event:

Event Name Description

Event Name	Description
`realtimeUpdateComplete`	This event is raised every time the real-time gauge updates itself with new data. This event is raised in any of the following cases: Real-time update using `datastreamURL` Real-time update using JavaScript API (using `setData`, `feedData`, `setDataForId` functions) Real-time update of the gauge through user interaction (through edit mode) The event arguments provided in the advanced model are: `eventObject` : This object contains the `eventId`, `eventType`, and `sender` properties. `argumentsObject` : This object contains the values of the updated data and the previous data.

realtimeUpdateComplete

This event is raised every time the real-time gauge updates itself with new data.
This event is raised in any of the following cases:

Real-time update using datastreamURL

Real-time update using JavaScript API (using setData, feedData, setDataForId functions)

Real-time update of the gauge through user interaction (through edit mode)

The event arguments provided in the advanced model are:

eventObject : This object contains the eventId, eventType, and sender properties.

argumentsObject : This object contains the values of the updated data and the previous data.

The data structure needed to configure the realTimeUpdateComplete event for a real-time thermometer gauge is given below:

JSON
XML

{ "chart": { "caption": "Temperature Monitor", "subcaption": " Central cold store", "lowerLimit": "-10", "upperLimit": "0", "decimals": "1", "numberSuffix": "°C", "showhovereffect": "1", "thmFillColor": "#008ee4", "showGaugeBorder": "1", "gaugeBorderColor": "#008ee4", "gaugeBorderThickness": "2", "gaugeBorderAlpha": "30", "thmOriginX": "100", "chartBottomMargin": "20", "valueFontColor": "#000000", "theme": "fint" }, "value": "-6", "annotations": { "showbelow": "0", "groups": [ { "id": "indicator", "items": [ { "id": "background", "type": "rectangle", "alpha": "50", "fillColor": "#AABBCC", "x": "$gaugeEndX-40", "tox": "$gaugeEndX", "y": "$gaugeEndY+54", "toy": "$gaugeEndY+72" } ] } ] } }

{
    "chart": {
        "caption": "Temperature Monitor",
        "subcaption": " Central cold store",
        "lowerLimit": "-10",
        "upperLimit": "0",
        "decimals": "1",
        "numberSuffix": "°C",
        "showhovereffect": "1",
        "thmFillColor": "#008ee4",
        "showGaugeBorder": "1",
        "gaugeBorderColor": "#008ee4",
        "gaugeBorderThickness": "2",
        "gaugeBorderAlpha": "30",
        "thmOriginX": "100",
        "chartBottomMargin": "20",
        "valueFontColor": "#000000",
        "theme": "fint"
    },
    "value": "-6",
    "annotations": {
        "showbelow": "0",
        "groups": [
            {
                "id": "indicator",
                "items": [
                    {
                        "id": "background",
                        "type": "rectangle",
                        "alpha": "50",
                        "fillColor": "#AABBCC",
                        "x": "$gaugeEndX-40",
                        "tox": "$gaugeEndX",
                        "y": "$gaugeEndY+54",
                        "toy": "$gaugeEndY+72"
                    }
                ]
            }
        ]
    }
}

A thermometer gauge configured to listen to the realTimeUpdateError event looks like this:

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Given below is a brief description of the realTimeUpdateError event:

Event Name	Description
`realtimeUpdateError`	This event is raised when an error occurs while performing real-time update using `datastreamURL`. The event arguments provided in the advanced model are: 1. `eventObject` : This object contains `eventId`, `eventType` and `sender` properties. 2. `argumentsObject` : This object contains the property listed below: a. `httpStatus` : It contains the HTTP Error status value as number (e.g., 404)

The data structure needed to configure the realTimeUpdateError event for a real-time thermometer gauge is given below:

JSON
XML

{
    "chart": {
        "caption": "Temperature Monitor",
        "subcaption": " Central cold store",
        "lowerLimit": "-10",
        "upperLimit": "0",
        "numberSuffix": "°C",
        "decimals": "1",
        "showhovereffect": "1",
        "thmFillColor": "#008ee4",
        "showGaugeBorder": "1",
        "gaugeBorderColor": "#008ee4",
        "gaugeBorderThickness": "2",
        "gaugeBorderAlpha": "30",
        "thmOriginX": "100",
        "dataStreamURL": "resources/php/dummyUrl.php",
        "refreshInterval": "5",
        "theme": "fint"
    },
    "value": "-6"
}

Troubleshooting Real-time Gauges

While accessing any of the JavaScript methods listed above, if you get an error like "... is not a function of ...",

Make sure that you are not calling the JavaScript method before the chart has loaded and rendered. You need to use the FC_Rendered function or define the event listener for the Rendered event of the chart to track the loading of the chart.
Make sure that you are NOT running the chart from the local file system (C:\ , D:\). Instead, run the chart from behind a server (localhost - IIS, Apache etc.). This is because the default security settings do not allow the chart to perform JavaScript interactions on the local file system, unless otherwise specifically set.

There! You have now seen how you can configure real-time updates and events for gauges and troubleshoot them.