require(["esri/layers/StreamLayer"], function(StreamLayer) { /* code goes here */ });
Class: esri/layers/StreamLayer
Inheritance: StreamLayer FeatureLayer Layer Accessor
Since: ArcGIS API for JavaScript 4.0

The stream layer extends the feature layer to add the ability to connect to a stream of data using HTML5 WebSockets. It connects to a server that emits geographic features continuously. While the feature layer is used to map relatively static data, the stream layer is suitable when you would like to map dynamic streams of data that are unbounded and continuous. When a stream layer is added to a map, users are able to see real-time updates pushed out by the server.

A real-time-enabled data server is required to use this class. The ArcGIS Geoevent Extension for Server is a tool you may use to set up and configure your data stream. In addition, version 10.3 of ArcGIS GeoEvent Extension for Server exposes stream services. To learn more about this, please see the Stream Services documentation.

You may also use your own web socket server, as long as it emits geographic features in the Esri JSON format.

The number of features coming from a real-time feed can overload the browser and make the browser unresponsive. Use the purgeOptions construction option to define rules that specify how to remove data when new messages are received and the layer is refreshed.

WebSockets are a feature of HTML5. Most browsers are supporting WebSockets in recent versions. However, they are not supported by all versions of all browsers. To get more information about WebSockets and to test if a browser supports WebSockets, visit WebSocket.org.

An instance of this class is also a Promise. This allows you to execute code once the promise resolves, or when the layer finishes loading its resources. See then() for additional details.

See also:

Constructors

new StreamLayer(properties)

Parameter:
properties Object
optional

See the properties for a list of all the properties that may be passed into the constructor.

Example:
var streamLayer = new StreamLayer({
  url: "https://geoeventsample3.esri.com:6080/arcgis/rest/services/SeattleBus/StreamServer",
  purgeOptions: {
    displayCount: 1000
  }
});

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
NameTypeSummary
String

The copyright text as defined by the map service.

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String

The name of the class.

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String

The SQL where clause used to filter features on the client.

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Object

Specifies how graphics are placed on the vertical axis (z).

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Object

Configures the method for decluttering overlapping features in the view.

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Field[]

An array of fields in the layer.

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Object

Contains the attribute and spatial filters used to filter messages sent to the client by a Stream Service.

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String

The version of the geodatabase of the feature service data.

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Extent

An extent object used to filter features.

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String

The geometry type of features in the layer.

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String

The unique ID assigned to the layer.

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LabelClass[]

The label definition for this layer, specified as an array of LabelClass.

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Boolean

Indicates whether to display labels for this layer.

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Boolean

Indicates whether the layer will be included in the legend.

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String

Indicates how the layer should display in the LayerList widget.

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Boolean

Indicates whether the layer's resources have loaded.

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Error

The Error object returned if an error occurred while loading.

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String

Represents the status of a load operation.

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Object[]

A list of warnings which occurred while loading.

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Number

Maximum number of features to show per trackId.

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Number

The maximum scale at which the layer is visible in the view.

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Number

The minimum scale at which the layer is visible in the view.

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String

The name of one of the provided fields for each graphic containing a unique value or identifier for that graphic.

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Number

The opacity of the layer.

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String[]

An array of field names from the service to include in the FeatureLayer.

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Boolean

Indicates whether to display popups when features in the layer are clicked.

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PopupTemplate

The popup template for the layer.

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PortalItem

The portal item from which the layer is loaded.

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Object

Options for purging stale features.

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Renderer

The renderer assigned to the layer.

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Boolean

Apply perspective scaling to screen-size point symbols in a SceneView.

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SpatialReference

The spatial reference of the layer.

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String

The title of the layer used to identify it in places such as the Legend and LayerList widgets.

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String

Token generated by the token service using the specified userId and password.

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String

For StreamLayer the type is stream.

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String

The URL of the stream service.

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Number

The version of ArcGIS Server in which the layer is published.

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Boolean

Indicates if the layer is visible in the View.

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Property Details

The copyright text as defined by the map service.

declaredClassStringreadonly

The name of the class. The declared class name is formatted as esri.folder.className.

definitionExpressionString

Deprecated
  • since version 4.3.

The SQL where clause used to filter features on the client. Use StreamLayer.filter.where when creating the service or StreamLayer.updateFilter() when changing the attribute filter instead of this property.

elevationInfoObject

Specifies how graphics are placed on the vertical axis (z). This property may only be used in a SceneView. See the ElevationInfo sample for an example of how this property may be used.

Properties:
mode String

Defines how the graphic is placed with respect to the terrain surface. returnZ must be set to true if z-values of the features should be considered for the elevation mode. If the geometry consists of multiple points (e.g. lines or polygons), the elevation is evaluated separately for each point. See the table below for a list of possible values.

ModeDescription
on-the-groundGraphics are draped on the terrain surface. This is the default value for features with Polyline or Polygon geometries and features with Point geometries rendered with ObjectSymbol3DLayers.
relative-to-groundThe graphic is placed at an elevation relative to the terrain surface. The graphic's elevation is determined by summing up the terrain elevation, the offset value and the geometry's z-value (if present). This is the default value for Point geometries rendered with IconSymbol3DLayers.
absolute-heightGraphics are placed at an absolute height above sea level. This height is determined by summing up the offset value and the geometry's z-value (if present). It doesn't take the elevation of the terrain into account. This is the default value of features with any geometry type where hasZ is true.
relative-to-sceneGraphics are aligned to buildings and other objects part of 3D Object SceneLayer or IntegratedMeshLayer, depending on which has higher elevation. If the graphic is not directly above a building or any other feature, it is aligned to the terrain surface elevation. If present, z-values will be ignored.
offset Number
optional

An elevation offset in meters, which is added to the vertical position of the graphic. When mode = "on-the-ground", this property has no effect.

featureReductionObject

Since: ArcGIS API for JavaScript 4.4

Configures the method for decluttering overlapping features in the view. If this property is not set (or set to null), every feature is drawn individually.

Currently this property is only supported in 3D SceneViews for point features with non-draped Icons or Text symbol layers.

declutter

Property:
type String

Type of the decluttering method. The only supported type at the moment is "selection". In this method, some of the overlapping features are hidden such that none of the remaining features intersect on screen. Label deconfliction also respects this option and hides labels that would overlap with the features of this layer.

See also:
Example:
layer.featureReduction = {
  type: "selection"
};

An array of fields in the layer. Each field represents an attribute that may contain a value for each feature in the layer. For example, a field named POP_2015, stores information about total population as a numeric value for each feature; this value represents the total number of people living within the geographic bounds of the feature.

This property must be set in the constructor when creating a FeatureLayer from client-side graphics. To create FeatureLayers from client-side graphics you must also set the source, objectIdField, spatialReference, and geometryType properties.

See also:
Example:
// define each field's schema
var fields = [
 new Field({
   name: "ObjectID",
   alias: "ObjectID",
   type: "oid"
 }), new Field({
   name: "description",
   alias: "Description",
   type: "string"
 }), new Field ({
   name: "title",
   alias: "Title",
   type: "string"
 })
];

// See the sample snippet for the source property
var layer = new FeatureLayer({
  source: features,
  fields: fields,
  objectIdField: "ObjectID",  // field name of the Object IDs
  geometryType: "point"
});

filterObjectreadonly

Since: ArcGIS API for JavaScript 4.3

Contains the attribute and spatial filters used to filter messages sent to the client by a Stream Service. This property can be set in the constructor but is read-only after the layer is created. To change the filter after the layer is created, use the updateFilter() method.

Properties:
geometry Extent
optional

A spatial filter for filtering features. Only features that intersect the given geometry are displayed in the view.

where String
optional

A SQL where clause used to filter features by attributes.

See also:
Example:
var layer = new StreamLayer({
  url: streamLayerUrl,
  // only displays features within the view's visible extent
  // and features whose route id is 20
  filter: {
    geometry: view.extent.clone(),
    where: "route_id = 20"
  }
});

gdbVersionString

The version of the geodatabase of the feature service data. Read the Overview of versioning topic for more details about this capability.

geometryDefinitionExtent

Deprecated
  • since version 4.3.

An extent object used to filter features. Only features intersecting the extent are displayed in the view. Instead of using this property, use StreamLayer.filter.geometry when creating the service or StreamLayer.updateFilter() when changing the spatial filter.

geometryTypeString

The geometry type of features in the layer. For StreamLayer, the geometryType is always point.

The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.

labelingInfoLabelClass[]

The label definition for this layer, specified as an array of LabelClass. Use this property to specify labeling properties for the layer such as label expression, placement, and size.

For labels to display in the view, the labelsVisible property of this layer must be set to true.

Known Limitations

There is no support for labeling in 2D. Labeling is only supported in 3D SceneViews.

See also:
Example:
var statesLabelClass = new LabelClass({
  labelExpressionInfo: { value: "{NAME}" },
  symbol: new TextSymbol({
    color: "black",
    haloSize: 1,
    haloColor: "white"
  })
});

featureLayer.labelsVisible = true;
featureLayer.labelingInfo = [ statesLabelClass ];

labelsVisibleBoolean

Indicates whether to display labels for this layer. If true, labels will appear as defined in the labelingInfo property.

Known Limitations

There is no support for labeling in 2D. Labeling is only supported in 3D SceneViews.

Default Value: false
See also:

legendEnabledBoolean

Indicates whether the layer will be included in the legend.

Default Value: true

listModeString

Indicates how the layer should display in the LayerList widget. The known values are listed below.

ValueDescription
showThe layer is visible in the table of contents.
hideThe layer is hidden in the table of contents.
hide-childrenIf the layer is a GroupLayer, hide the children layers from the table of contents.
Default Value: show

loadedBooleanreadonly

Indicates whether the layer's resources have loaded. When true, all the properties of the object can be accessed.

Default Value: false

loadErrorErrorreadonly

The Error object returned if an error occurred while loading.

Default Value: null

loadStatusStringreadonly

Represents the status of a load operation.

ValueDescription
not-loadedThe object's resources have not loaded.
loadingThe object's resources are currently loading.
loadedThe object's resources have loaded without errors.
failedThe object's resources failed to load. See loadError for more details.
Default Value: not-loaded

loadWarningsObject[]readonly

A list of warnings which occurred while loading.

maximumTrackPointsNumber

Maximum number of features to show per trackId

maxScaleNumber

The maximum scale at which the layer is visible in the view. If the map is zoomed in beyond this scale, the layer will not be visible. A value of 0 means the layer does not have a maximum scale.

Default Value: 0
Examples:
//The layer will not be visible when the
//view is zoomed beyond a scale of 1:1,000
layer.maxScale = 1000;
//The layer's visibility is not restricted to a maximum scale.
layer.maxScale = 0;

minScaleNumber

The minimum scale at which the layer is visible in the view. If the map is zoomed out beyond this scale, the layer will not be visible. A value of 0 means the layer does not have a minimum scale.

Default Value: 0
Examples:
//The layer will not be visible when the view
//is zoomed beyond a scale of 1:3,000,000
layer.minScale = 3000000;
//The layer's visibility is not restricted to a minimum scale.
layer.minScale = 0;

objectIdFieldString

The name of one of the provided fields for each graphic containing a unique value or identifier for that graphic. This is required when constructing a FeatureLayer from a collection of client-side graphics.

When creating a FeatureLayer from client-side graphics, the source, fields, spatialReference, and geometryType properties must also be set.

See also:
Example:
// See the sample snippet for the source and fields properties
var layer = new FeatureLayer({
  source: features,
  fields: fields,
  objectIdField: "ObjectID",  // field name of the Object IDs
  geometryType: "point"
});

opacityNumber

The opacity of the layer. This value can range between 1 and 0, where 0 is 100 percent transparent and 1 is completely opaque.

Default Value: 1
Example:
// Makes the layer 50% transparent
layer.opacity = 0.5;

outFieldsString[]

An array of field names from the service to include in the FeatureLayer. If not specified, the layer will only return the OBJECTID field. To fetch the values from all fields in the layer, use ["*"]. This is particularly useful when editing features.

Examples:
// Includes all fields from the service in the layer
fl.outFields = ["*"];
// Includes only the specified fields from the service in the layer
fl.outFields = ["NAME", "POP_2010", "FIPS", "AREA"];

popupEnabledBoolean

Indicates whether to display popups when features in the layer are clicked.

Default Value: true

popupTemplatePopupTemplate autocast

The popup template for the layer. When set on the layer, the popupTemplate allows users to access attributes and display their values in the view's popup when a feature is selected using text and/or charts. See the PopupTemplate sample for an example of how PopupTemplate interacts with a FeatureLayer.

portalItemPortalItem

The portal item from which the layer is loaded. If the portal item references a Feature Service or Scene Service, then you can specify a single layer to to load with the layerId property.

Examples:
// while this example uses FeatureLayer, this same pattern can be
// used for other layers that may be loaded from portalItem ids
var lyr = new FeatureLayer({
  portalItem: {  // autocasts as new PortalItem()
    id: "caa9bd9da1f4487cb4989824053bb847"
  }  // the first layer in the service is returned
});
// set hostname when using an on-premise portal (default is Arcgis Online)
// esriConfig.portalUrl = "http://myHostName.esri.com/arcgis";

// while this example uses FeatureLayer, this same pattern can be
// used for SceneLayers
var lyr = new FeatureLayer({
  portalItem: {  // autocasts as new PortalItem()
    id: "8d26f04f31f642b6828b7023b84c2188"
  },
  // loads the third item in the given feature service
  layerId: 2
});

purgeOptionsObject

Options for purging stale features. Use these options to avoid overloading the browser with graphics.

Properties:
displayCount Number

The maximum number of features to display. Excess features are purged from the beginning of the graphics array.

age Number

The maximum time in minutes that a feature should be kept. After this time, the feature is removed from the layer.

rendererRenderer

The renderer assigned to the layer. The renderer defines how to visualize each feature in the layer. Depending on the renderer type, features may be visualized with the same symbol, or with varying symbols based on the values of provided attribute fields or functions.

See also:
Example:
// all features in the layer will be visualized with
// a 6pt black marker symbol and a thin, white outline
layer.renderer = new SimpleRenderer({
  symbol: new SimpleMarkerSymbol({
    size: 6,
    color: "black",
    outline: {
      width: 0.5,
      color: "white"
    }
  })
});

screenSizePerspectiveEnabledBoolean

Since: ArcGIS API for JavaScript 4.4

Apply perspective scaling to screen-size point symbols in a SceneView. When true, screen sized objects such as icons, labels or callouts integrate better in the 3D scene by applying a certain perspective projection to the sizing of features. This only applies when using a SceneView.

layer.screenSizePerspectiveEnabled = true

screen-size-perspective

layer.screenSizePerspectiveEnabled = false

no-screen-size-perspective

Known Limitations

Screen size perspective is currently not optimized for situations where the camera is very near the ground, or for scenes with point features located far from the ground surface. In these cases it may be better to turn off screen size perspective. As screen size perspective changes the size based on distance to the camera, it should be set to false when using size visual variables.

Default Value: true
See also:

spatialReferenceSpatialReference autocast

The spatial reference of the layer. When creating the layer from a url, the spatial reference is read from the service.

This property should be set explicitly when creating a FeatureLayer from client-side graphics. When creating a FeatureLayer from client-side graphics, the fields, objectIdField, source, and geometryType properties must also be set.

titleString

The title of the layer used to identify it in places such as the Legend and LayerList widgets.

When loading a layer by service url, the title is derived from the service name. If the service has several layers, then the title of each layer will be the concatenation of the service name and the layer name. When the layer is loaded from a portal item, the title of the portal item will be used instead. Finally, if a layer is loaded as part of a webmap or a webscene, then the title of the layer as stored in the webmap/webscene will be used.

tokenStringreadonly

Token generated by the token service using the specified userId and password. The recommended approach to pass a token on a layer is to use IdentityManager.registerToken().

typeStringreadonly

For StreamLayer the type is stream.

The URL of the stream service. This is set in the url parameter of the constructor.

Example:
var layer = new StreamLayer({
 url: "https://geoeventsample3.esri.com:6443/arcgis/rest/services/SeattleBus/StreamServer"
});

versionNumberreadonly

The version of ArcGIS Server in which the layer is published.

Example:
// Prints the version number to the console - e.g. 10.2, 10.3, 10.41, etc.
console.log(layer.version);

visibleBoolean

Indicates if the layer is visible in the View. When false, the layer may still be added to a Map instance that is referenced in a view, but its features will not be visible in the view.

Default Value: true
Example:
// The layer is no longer visible in the view
layer.visible = false;

Method Overview

NameReturn TypeSummary
Promise

An instance of this class is a Promise.

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Cancels a load() operation if it is already in progress.

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Boolean

Indicates whether there is an event listener on the instance that matches the provided event name.

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Boolean

An instance of this class is a Promise.

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Boolean

An instance of this class is a Promise.

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Boolean

An instance of this class is a Promise.

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Promise

Loads the resources referenced by this class.

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Object

Registers an event handler on the instance.

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Promise

An instance of this class is a Promise.

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Promise

An instance of this class is a Promise.

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Promise

Updates the filter on the layer.

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Method Details

always(callbackOrErrback){Promise}inherited

An instance of this class is a Promise. Therefore always() may be used to execute a function if the promise is rejected or resolved. The input function will always execute no matter the response. For more information about promises, see the Working with Promises guide page.

Parameter:
callbackOrErrback Function
optional

The function to execute when the promise is rejected or resolved.

Returns:
TypeDescription
PromiseReturns a new promise for the result of callbackOrErrback.
Example:
// Although this example uses MapView, any class instance that is a promise may use always() in the same way
var view = new MapView();
view.always(function(){
  // This function will always execute whether or not the promise is resolved or rejected
});

cancelLoad()inherited

Cancels a load() operation if it is already in progress.

hasEventListener(type){Boolean}inherited

Indicates whether there is an event listener on the instance that matches the provided event name.

Parameter:
type String

The name of the event.

Returns:
TypeDescription
BooleanReturns true if the class supports the input event.

isFulfilled(){Boolean}inherited

An instance of this class is a Promise. Therefore isFulfilled() may be used to verify if the promise is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned. See the Working with Promises guide page for more information about promises.

Returns:
TypeDescription
BooleanIndicates whether the promise has been fulfilled (either resolved or rejected).

isRejected(){Boolean}inherited

An instance of this class is a Promise. Therefore isRejected() may be used to verify if the promise is rejected. If it is rejected, true will be returned. See the Working with Promises guide page for more information about promises.

Returns:
TypeDescription
BooleanIndicates whether the promise has been rejected.

isResolved(){Boolean}inherited

An instance of this class is a Promise. Therefore isResolved() may be used to verify if the promise is resolved. If it is resolved, true will be returned. See the Working with Promises guide page for more information about promises.

Returns:
TypeDescription
BooleanIndicates whether the promise has been resolved.

Loads the resources referenced by this class. This method automatically executes for a View and all of the resources it references in Map if the view is constructed with a map instance.

This method must be called by the developer when accessing a resource that will not be loaded in a View.

Returns:
TypeDescription
PromiseResolves when the resources have loaded.

on(type, listener){Object}inherited

Registers an event handler on the instance. Call this method to hook an event with a listener. See the Events summary table for a list of listened events.

Parameters:
type String

The name of event to listen for.

listener Function

The function to call when the event is fired.

Returns:
TypeDescription
ObjectReturns an event handler with a remove() method that can be called to stop listening for the event.
PropertyTypeDescription
removeFunctionWhen called, removes the listener from the event.
See also:
Example:
view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});

otherwise(errback){Promise}inherited

An instance of this class is a Promise. Use otherwise() to call a function once the promise is rejected.

Parameter:
errback Function
optional

The function to execute when the promise fails.

Returns:
TypeDescription
PromiseReturns a new promise for the result of errback.
Example:
// Although this example uses MapView, any class instance that is a promise may use otherwise() in the same way
var view = new MapView();
view.otherwise(function(error){
  // This function will execute if the promise is rejected due to an error
});

then(callback, errback, progback){Promise}inherited

An instance of this class is a Promise. Therefore then() may be leveraged once an instance of the class is created. This method takes two input parameters: a callback function and an errback function. The callback executes when the promise resolves (when the instance of the class loads). The errback executes if the promise fails. See the Working with Promises guide page for additional details.

Parameters:
callback Function
optional

The function to call when the promise resolves.

errback Function
optional

The function to execute when the promise fails.

progback Function
optional

The function to invoke when the promise emits a progress update.

Returns:
TypeDescription
PromiseReturns a new promise for the result of callback that may be used to chain additional functions.
Example:
// Although this example uses MapView, any class instance that is a promise may use then() in the same way
var view = new MapView();
view.then(function(){
  // This function will execute once the promise is resolved
}, function(error){
  // This function will execute if the promise is rejected due to an error
});

updateFilter(filterChanges){Promise}

Since: ArcGIS API for JavaScript 4.3

Updates the filter on the layer. The filter is updated on all views that contain the layer. If the input filterChanges object is undefined or null, the spatial and attribute filters are removed. To update the filter on a single layer view associated with the layer, use the StreamLayerView.updateFilter() method after getting the layer view object.

Filter changes only apply to incoming features. Features already displayed in the view are not filtered. Therefore, you may want to clear the graphics in the layer view prior to applying a new filter. To do so, get the layer view then call removeAll() on the StreamLayerView.graphics. You may also filter features already present in the view using the Collection methods. See the examples below.

Parameters:
filterChanges Object

Updates the spatial and attribute filters on the layer and all of its associated views. If null, all filters are cleared.

Specification:
geometry Extent

A spatial filter for filtering features. Only features that intersect the given geometry are displayed in the view(s). If null, the spatial filter is cleared.

where String

A SQL where clause used to filter features by attributes. If null, the attribute filter is cleared.

Returns:
TypeDescription
PromiseResolves to an object that has an error property if the update was not successful. The object also has a filter property that indicates the filter set on the layer.
See also:
Examples:
view.whenLayerView(layer)
 .then(function(layerView){
   layerView.graphics.removeAll();

   // updates the spatial filter based on the current view's extent
   // and removes the attribute filter
   layer.updateFilter({
     geometry: view.extent.filter(),
     where: null
   });
 });
// clears all filters from the layer
layer.updateFilter(null);

Event Overview

NameTypeSummary
{view: View,layerView: LayerView}

Fires after the layer's LayerView is created and rendered in a view.

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{view: View,layerView: LayerView}

Fires after the layer's LayerView is destroyed and no longer renders in a view.

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Event Details

layerview-createinherited

Fires after the layer's LayerView is created and rendered in a view.

Properties:
view View

The view in which the layerView was created.

layerView LayerView

The LayerView rendered in the view representing the layer in layer.

See also:
Example:
// This function will fire each time a layer view is created for this
// particular view.
layer.on("layerview-create", function(event){
  // The LayerView for the layer that emitted this event
  event.layerView;
});

layerview-destroyinherited

Fires after the layer's LayerView is destroyed and no longer renders in a view.

Properties:
view View

The view in which the layerView was destroyed.

layerView LayerView

The destroyed LayerView representing the layer.

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