The bulb 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 auto-updates to reflect the current state of data. There are two different ways to update the angular 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 LED 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 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 25 (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 bulb gauge configured for real-time updates using JavaScript API looks like this:
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:
Configuring Real-time Updates Using Server-side Scripts
A bulb gauge configured for real-time updates using server-side script looks like this:
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 we have special characters as a part of your data stream URL, like ? or &, we will need 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 real-time data URL, so as to maintain a state. Please see the section Real-time Capabilities >Adding Data Stamp. |
The data structure needed to configure real-time updates using server-side script is given below:
Stopping/Restarting Updates
A bulb gauge configured to stop receiving real-time updates looks like this:
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/restart receiving real-time updates is given below:
Configuring Real-time Events
FusionCharts Suite XT introduces two events, realTimeUpdateComplete and realTimeUpdateError, to track real-time updates on gauges.
A real-time bulb gauge configured to listen to the realTimeUpdateComplete event looks like this:
Given below is a brief description of the realTimeUpdateComplete event:
| Attribute Name | Description |
|---|---|
realtimeUpdateComplete |
This event is raised every the real-time gauge updates itself with new data. This event is raised in any of the following cases: Real-time update using datastreamURLReal-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 bulb gauge is given below:
A bulb gauge configured to listen to the realTimeUpdateError event looks like this:
Given below is a brief description of the realTimeUpdateError event:
| Attribute 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:
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_Renderedfunction or define the event listener forRenderedevent of chart to track the loading of chart as explained in theFusionWidgets XT and JavaScriptsection.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.
There! You have now seen how you can configure real-time updates and events for gauges and troubleshoot them.