Source: https://developers.woosmap.com/products/geofencing-sdk/cordova-plugin/guides/monitor-pois/

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# Monitor POIs with Geofence



## Create and monitor Geofences

Use region monitoring to determine when the user enters or leaves a geographic region.

Region monitoring (also known as Geofencing) combines awareness of the user's current location with awareness of the
user's proximity to locations that may be of interest. This region is a way for your app to be alerted when the user
enters or exits a geographical region. To mark a location of interest, you specify its latitude and longitude. To adjust
the proximity for the location, you add a radius. The latitude, longitude, and radius define a Geofence, creating a
circular area, or fence, around the location of interest. Find more details about Geofences in
the [Geofence documentation](/products/geofencing-sdk/geofencing/)

## Adding and removing regions

Call `addRegion` method to add a region that you want to monitor. Method will accept an object with the following
attributes:

* **regionId** - Id of the region
* **lat** - Latitude
* **lng** - Longitude
* **radius** - Radius in meters

```js
const request = {
    "lat": 51.50998000,
    "lng": -0.13370000,
    "regionId": "7F91369E-467C-4CBD-8D41-6509815C4780",
    "radius": 10
};
cordova.plugins.WoosmapGeofencing.addRegion(request, success, error);
```

### Remove regions

Call `removeRegion` method to add a region that you want to monitor. Method will accept the following parameter, and
passing a null value will remove all the regions.

* **regionId** - Id of the region
* **lat** - Latitude
* **lng** - Longitude
* **radius** - Radius in meters

```js
const request = {
    "lat": 51.50998000,
    "lng": -0.13370000,
    "regionId": "7F91369E-467C-4CBD-8D41-6509815C4780",
    "radius": 10
};
cordova.plugins.WoosmapGeofencing.removeRegion(request, success, error);
```

Whenever the user crosses the boundary of one of your app's registered regions, the system notifies your app.

On the object `Region`, there are an boolean `didEnter` that indicate if you enter or exit of the region. You have
another boolean `fromPositionDetection` to know if the detection was launch by the position detection or by the system
detection.

Regions have an associated identifier, which this method uses to look up information related to the region and perform
the associated action.

### Get regions from the local database

Call `getRegions` method to get an array of Regions from the local db.

```js
const success = function (regions) {
    showSuccessToast("Total Regions: " + regions.length);
};
cordova.plugins.WoosmapDb.getRegions(success, error);
```

### Watch Region to track region's events

Call `watchRegions` method to track Regions. Method will invoke a callback with Region object. Method will return a
watch id which can be used later to remove the callback.

```js
const regionCallback = function (region) {
    console.log("Region:" + region);
};

const error = function (err) {
    console.log(err);
};

const regionWatchId = cordova.plugins.WoosmapGeofencing.watchRegions(regionCallback, error);
```

To remove watch:

```js
cordova.plugins.WoosmapGeofencing.clearRegionsWatch(regionWatchId, success, error);
```

## Create regions from Woosmap Search API assets

Region monitoring is a natural complement to Search requests performed on collected locations. Indeed, Search requests
help monitoring the approach to some assets you want to monitor. On every collected location you are aware of the
surrounding assets (distance to them and even time if using Distance API request). You can then decide to monitor some of
those surrounding assets (e.g. the closest ones). Region monitoring is designed to do so.

To create region around the nearest result of the Search API request, choose a tracking profile with the tracking
properties `searchAPICreationRegionEnable` enable.

**Pre-requisites**  
You must define a Woosmap private API key to request the Woosmap Search API. How set an Woosmap private key is explain
in the [Initializing the plugin section.](/products/geofencing-sdk/cordova-plugin/guides/setup/#initializing-the-plugin)