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StreamLayerView

Class: esri/views/layers/StreamLayerView
Inheritance: StreamLayerView LayerView Accessor
Since: ArcGIS API for JavaScript 4.4

Represents the LayerView of a StreamLayer after it has been added to a Map in either a MapView or SceneView.

The StreamLayerView is responsible for rendering a StreamLayer's features as graphics in the View. The methods in the StreamLayerView provide developers with the ability to query and highlight graphics in the view. See the code snippets in the methods below for examples of how to access client-side graphics from the view.

The StreamLayer extends the FeatureLayer 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 FeatureLayer 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 StreamLayer is added to a map, users are able to see any real-time updates pushed out by the server. For more information, read the documentation of StreamLayer.

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.

See also:

Property Overview

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

The error that explains an unsuccessful attempt to connect to the stream service or an unexpected disconnection from the stream service.

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more detailsStreamLayerView
String

The status of the Web Socket connection with the stream service.

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more detailsStreamLayerView
String

The name of the class.

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more detailsAccessor
FeatureFilter

The geometry and attribute filter.

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more detailsStreamLayerView
Collection<Graphic>

Contains the collection of graphics visible in the layer view for the live stream.

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more detailsStreamLayerView
Layer

The layer being viewed.

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more detailsLayerView
Boolean

Value is true if the layer is suspended (i.e., layer will not redraw or update itself when the extent changes).

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more detailsLayerView
Boolean

Value is true when the layer is updating; for example, if it is in the process of fetching data.

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more detailsLayerView
Boolean

When true, the layer is visible in the view.

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more detailsLayerView

Property Details

connectionError Errorreadonly

The error that explains an unsuccessful attempt to connect to the stream service or an unexpected disconnection from the stream service.

connectionStatus Stringreadonly

The status of the Web Socket connection with the stream service. This property can be watched to see if the connection is lost unexpectedly.

Possible Values: connected | disconnected

declaredClass Stringreadonly inherited
Since: ArcGIS API for JavaScript 4.7

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

filter FeatureFilterautocastreadonly

The geometry and attribute filter. Only the features that satisfy the filter are displayed.

Deprecated
  • since version 4.8. Will be removed at 4.12.

Contains the collection of graphics visible in the layer view for the live stream. Graphics may be removed from the layer view by calling the removeAll() method from Collection.

This property is deprecated. Use queryFeatures method instead.

Example:
// removes all stream layer graphics from view
// new messages add features to the view
view.whenLayerView(streamLayer)
  .then(function(layerView){
    layer.graphics.removeAll();
  });
layer Layerreadonly inherited

The layer being viewed.

suspended Booleanreadonly inherited

Value is true if the layer is suspended (i.e., layer will not redraw or update itself when the extent changes).

updating Booleanreadonly inherited

Value is true when the layer is updating; for example, if it is in the process of fetching data.

Default Value:false

When true, the layer is visible in the view. Set this property to false to hide the layer from the view.

Default Value:true

Method Overview

NameReturn TypeSummaryClass
Promise

Opens a web socket connection with the stream service to start receiving messages.

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more detailsStreamLayerView

Closes the web socket connection with the stream service.

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more detailsStreamLayerView
Boolean

Emits an event on the instance.

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more detailsStreamLayerView
Boolean

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

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more detailsStreamLayerView
Handle

Highlights the given feature(s).

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more detailsStreamLayerView
Boolean

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).

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more detailsLayerView
Boolean

isRejected() may be used to verify if creating an instance of the class is rejected.

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more detailsLayerView
Boolean

isResolved() may be used to verify if creating an instance of the class is resolved.

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more detailsLayerView
Object

Registers an event handler on the instance.

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more detailsStreamLayerView
Promise<Object>

Executes a Query against features available for drawing in the layer view and returns the Extent of features that satisfy the query.

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more detailsStreamLayerView
Promise<Number>

Executes a Query against features available for drawing in the layer view and returns the number of features that satisfy the query.

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more detailsStreamLayerView
Promise<FeatureSet>

Executes a Query against features available for drawing in the layer view and returns a FeatureSet.

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more detailsStreamLayerView
Promise<FeatureSet>

If a trackIdField is specified on the Stream Service, this method executes a Query against features available for drawing in the layer view and returns a FeatureSet of the latest observations for each trackID that satisfy the query.

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more detailsStreamLayerView
Promise<Number[]>

Executes a Query against features available for drawing in the layer view and returns array of the ObjectIDs of features that satisfy the input query.

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more detailsStreamLayerView
Promise<Object>

**This method is deprecated.

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more detailsStreamLayerView
Promise

when() may be leveraged once an instance of the class is created.

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more detailsLayerView

Method Details

connect(){Promise}
Deprecated
  • since version 4.9. Will be removed at 4.12.

Opens a web socket connection with the stream service to start receiving messages. This is called internally when the StreamLayer is added to a view.

The layer will now automatically connect when it is added to a view.

Returns:
TypeDescription
PromiseThe promise is resolved if the connection is successful or rejected with an error if the connection failed.
disconnect()
Deprecated
  • since version 4.9. Will be removed at 4.12.

Closes the web socket connection with the stream service. This is called internally when the StreamLayer is removed from a view. To verify when the connection is closed, watch the connectionStatus property.

The layer will now automatically disconnect when it is removed a view.

emit(type, event){Boolean}
Since: ArcGIS API for JavaScript 4.5

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters:
type String

The name of the event.

event Object
optional

The event payload.

Returns:
TypeDescription
Booleantrue if a listener was notified
hasEventListener(type){Boolean}

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.
highlight(target){Handle}

Highlights the given feature(s).

Parameter:
optional

The feature(s) to highlight. When passing a graphic or array of graphics, each feature must have a valid objectID. You may alternatively pass one or more objectIDs as a single number or an array.

Returns:
TypeDescription
HandleReturns a highlight handler with a remove() method that can be called to remove the highlight.
See also:
Example:
// highlight feature on pointer-move
view.on("pointer-move", function(event){
  view.hitTest(event).then(function(response){
    if (response.results.length) {
      var graphic = response.results.filter(function (result) {
        return result.graphic.layer === myLayer;
      })[0].graphic;

     view.whenLayerView(graphic.layer).then(function(layerView){
       layerView.highlight(graphic);
     });
    }
  });
});
isFulfilled(){Boolean}inherited

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned.

Returns:
TypeDescription
BooleanIndicates whether creating an instance of the class has been fulfilled (either resolved or rejected).
isRejected(){Boolean}inherited

isRejected() may be used to verify if creating an instance of the class is rejected. If it is rejected, true will be returned.

Returns:
TypeDescription
BooleanIndicates whether creating an instance of the class has been rejected.
isResolved(){Boolean}inherited

isResolved() may be used to verify if creating an instance of the class is resolved. If it is resolved, true will be returned.

Returns:
TypeDescription
BooleanIndicates whether creating an instance of the class has been resolved.
on(type, listener){Object}

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters:

A event type, or an array of event types, 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(s).
PropertyTypeDescription
removeFunctionWhen called, removes the listener from the event.
Example:
view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});
queryExtent(query, options){Promise<Object>}
Since: ArcGIS API for JavaScript 4.9

Executes a Query against features available for drawing in the layer view and returns the Extent of features that satisfy the query. If query parameters are not provided, the extent and count of all features available for drawing are returned.

Known Limitations

  • Queries on StreamLayerView are currently not supported in 3D SceneViews.
  • Spatial queries have the same limitations as those listed in the projection engine documentation.
  • Spatial queries are not currently supported if the layer view has any of the following SpatialReferences:
    • GDM 2000 (4742) – Malaysia
    • Gusterberg (Ferro) (8042) – Austria/Czech Republic
    • ISN2016 (8086) - Iceland
    • SVY21 (4757) - Singapore
Parameters:
optional
Autocasts from Object

Specifies the attributes and spatial filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the geometry parameter in the query object to the view's extent.

options Object
optional

An object with the following properties.

Specification:
optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns:
TypeDescription
Promise<Object>When resolved, returns the extent and count of the features that satisfy the input query. See the object specification table below for details.
PropertyTypeDescription
countNumberThe number of features that satisfy the input query.
extentExtentThe extent of the features that satisfy the query.
Example:
var layer = new StreamLayer({
  url: streamLayerUrl  // URL to a Stream Service
});

view.whenLayerView(layer).then(function(layerView){
  layerView.watch("updating", function(val){
    if(!val){  // wait for the layer view to finish updating
      layerView.queryExtent().then(function(results){
        view.goTo(results.extent);  // go to the extent of all the graphics in the layer view
      });
    }
  });
});
queryFeatureCount(query, options){Promise<Number>}
Since: ArcGIS API for JavaScript 4.9

Executes a Query against features available for drawing in the layer view and returns the number of features that satisfy the query. If query parameters are not provided, the count of all features available for drawing is returned.

Known Limitations

  • Queries on StreamLayerView are currently not supported in 3D SceneViews.
  • Spatial queries have the same limitations as those listed in the projection engine documentation.
  • Spatial queries are not currently supported if the layer view has any of the following SpatialReferences:
    • GDM 2000 (4742) – Malaysia
    • Gusterberg (Ferro) (8042) – Austria/Czech Republic
    • ISN2016 (8086) - Iceland
    • SVY21 (4757) - Singapore
Parameters:
optional
Autocasts from Object

Specifies the attributes and spatial filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the geometry parameter in the query object to the view's extent.

options Object
optional

An object with the following properties.

Specification:
optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns:
TypeDescription
Promise<Number>When resolved, returns the number of features satisfying the query.
Examples:
view.on("click", function(event){

  var query = new Query();
  query.geometry = event.mapPoint;  // obtained from a view click event
  query.spatialRelationship = "intersects";

  view.whenLayerView(layer).then(function(layerView){
    watchUtils.whenNotOnce(layerView, "updating")
    .then(function(){
      return layerView.queryFeatureCount(query);
    })
    .then(function(count){
      console.log(count);  // prints the number of the client-side graphics that satisfy the query
    });
  });
});
view.whenLayerView(layer).then(function(layerView){
  return layerView.queryFeatureCount()
}).then(function(count){
  console.log(count);  // prints the total number of client-side graphics to the console
});
queryFeatures(query, options){Promise<FeatureSet>}
Since: ArcGIS API for JavaScript 4.9

Executes a Query against features available for drawing in the layer view and returns a FeatureSet. If query parameters are not provided, all features available for drawing are returned.

Known Limitations

  • Queries on StreamLayerView are currently not supported in 3D SceneViews.
  • Spatial queries have the same limitations as those listed in the projection engine documentation.
  • Spatial queries are not currently supported if the layer view has any of the following SpatialReferences:
    • GDM 2000 (4742) – Malaysia
    • Gusterberg (Ferro) (8042) – Austria/Czech Republic
    • ISN2016 (8086) - Iceland
    • SVY21 (4757) - Singapore
Parameters:
optional
Autocasts from Object

Specifies the attributes and spatial filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the geometry parameter in the query object to the view's extent.

options Object
optional

An object with the following properties.

Specification:
optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns:
TypeDescription
Promise<FeatureSet>When resolved, a FeatureSet containing an array of graphic features is returned.
Examples:
view.whenLayerView(layer).then(function(layerView){
  layerView.watch("updating", function(val){
    if(!val){  // wait for the layer view to finish updating
      layerView.queryFeatures(query).then(function(results){
        console.log(results.features);  // prints the array of client-side graphics to the console
      });
    }
  });
});
// returns all the graphics from the layer view
view.whenLayerView(layer).then(function(layerView){
  layerView.watch("updating", function(val){
    if(!val){  // wait for the layer view to finish updating
      layerView.queryFeatures().then(function(results){
        console.log(results.features);  // prints all the client-side graphics to the console
      });
    }
  });
});
queryLatestObservations(query, options){Promise<FeatureSet>}
Since: ArcGIS API for JavaScript 4.9

If a trackIdField is specified on the Stream Service, this method executes a Query against features available for drawing in the layer view and returns a FeatureSet of the latest observations for each trackID that satisfy the query.

Known Limitations

  • Queries on StreamLayerView are currently not supported in 3D SceneViews.
  • Spatial queries have the same limitations as those listed in the projection engine documentation.
  • Spatial queries are not currently supported if the layer view has any of the following SpatialReferences:
    • GDM 2000 (4742) – Malaysia
    • Gusterberg (Ferro) (8042) – Austria/Czech Republic
    • ISN2016 (8086) - Iceland
    • SVY21 (4757) - Singapore
Parameters:
optional
Autocasts from Object

Specifies the attributes and spatial filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the geometry parameter in the query object to the view's extent.

options Object
optional

An object with the following properties.

Specification:
optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns:
TypeDescription
Promise<FeatureSet>When resolved, returns the FeatureSet that satisfy the input query.
Example:
var layer = new StreamLayer({
  url: streamLayerUrl  // URL to a Stream Service
});

view.whenLayerView(layer).then(function(layerView){
  layerView.watch("updating", function(val){
    if(!val){  // wait for the layer view to finish updating
      layerView.queryLatestObservations().then(function(results){
        console.log(results.features);  // prints all the client-side graphics to the console
      });
    }
  });
});
queryObjectIds(query, options){Promise<Number[]>}
Since: ArcGIS API for JavaScript 4.9

Executes a Query against features available for drawing in the layer view and returns array of the ObjectIDs of features that satisfy the input query. If query parameters are not provided, the ObjectIDs of all features available for drawing are returned.

Known Limitations

  • Queries on StreamLayerView are currently not supported in 3D SceneViews.
  • Spatial queries have the same limitations as those listed in the projection engine documentation.
  • Spatial queries are not currently supported if the layer view has any of the following SpatialReferences:
    • GDM 2000 (4742) – Malaysia
    • Gusterberg (Ferro) (8042) – Austria/Czech Republic
    • ISN2016 (8086) - Iceland
    • SVY21 (4757) - Singapore
Parameters:
optional
Autocasts from Object

Specifies the attributes and spatial filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the geometry parameter in the query object to the view's extent.

options Object
optional

An object with the following properties.

Specification:
optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns:
TypeDescription
Promise<Number[]>When resolved, returns an array of numbers representing the ObjectIDs of the features satisfying the query.
Examples:
view.on("click", function(event){

  var query = new Query();
  query.geometry = event.mapPoint;  // obtained from a view click event
  query.spatialRelationship = "intersects";

  view.whenLayerView(layer).then(function(layerView){
    watchUtils.whenNotOnce(layerView, "updating")
    .then(function(){
      return layerView.queryObjectIds(query);
    })
    .then(function(ids){
      console.log(ids);  // prints the ids of the client-side graphics to the console
    });
  });
});
// returns all the Ids from the graphics in the layer view
view.whenLayerView(layer).then(function(layerView){
  return layerView.queryObjectIds()
}).then(function(ids){
  console.log(ids);  // prints the ids of all the client-side graphics to the console
});
updateFilter(filter){Promise<Object>}
Deprecated
  • since version 4.11. Will be removed at version 4.12.

This method is deprecated. Update filter directly instead. Updates the filter on the StreamLayerView. The filter is updated only on the layer view from which it is called. To update the filter on all layer views generated from a common layer, use the StreamLayer.updateFilter() method. If the input filter object is undefined or null, the spatial and attribute filters are removed.

Filter changes only apply to incoming features. Features already displayed in the view will be removed automatically.

Parameters:
Specification:
filter Object

Updates the spatial and attribute filters. If null, all filters are cleared.

Specification:
geometry Extent
optional

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

where String
optional

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

Returns:
TypeDescription
Promise<Object>Resolves to an object that has a filter property, indicating the filter set on the stream service by the layer view. If the filter could not be updated, the promise is rejected with an error that explains why the filter failed to update.
See also:
Examples:
view.whenLayerView(layer)
 .then(function(layerView){

   // updates the spatial filter based on the current view's extent
   // and removes the attribute filter
   layerView.updateFilter({
     geometry: view.extent.filter(),
     where: null
   });
 });
// updates the attribute filter to only display features whose
// route ID is 110
layerView.updateFilter({
  where: "ROUTE_ID = 110"
});
// clears all filters from the layer
layerView.updateFilter(null);
when(callback, errback){Promise}inherited
Since: ArcGIS API for JavaScript 4.6

when() 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 instance of the class loads. The errback executes if the instance of the class fails to load.

Parameters:
callback Function
optional

The function to call when the promise resolves.

errback Function
optional

The function to execute when the promise fails.

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.when(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
});

Event Overview

NameTypeSummaryClass

Fires when the layer view receives data.

more details
more detailsStreamLayerView

Event Details

data-received

Fires when the layer view receives data. The event object contains the message properties received from the stream service.

API Reference search results

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