HttpDataSetReader

Source (.js)Source (.d.ts)

Introduction

The vtkHttpDataSetReader is using a custom format that only exist in vtk.js which aims to simplify data fetching in an HTTP context. Basically the format is composed of a JSON metadata file referencing all the required data array as side binary files along with all the dataset configuration (i.e.: type, extent...).

Usage

import vtkHttpDataSetReader from '@kitware/vtk.js/IO/Core/HttpDataSetReader';

const reader = vtkHttpDataSetReader.newInstance();
reader.setURL('/Data/can.ex2/index.json').then((reader, dataset) => {
  console.log('Metadata loaded with the geometry', dataset);

  reader.getArrays().forEach(array => {
    console.log('-', array.name, array.location, ':', array.enable);
  });

  reader.update()
    .then((reader, dataset) => {
      console.log('dataset fully loaded', dataset);
    });
});

Methods

clearCache

Clears all cached entries.

enableArray

Enable or disable a given array.

reader.enableArray('pointData', 'Temperature');
reader.enableArray('pointData', 'Pressure', false);
reader.enableArray('cellData', 'CellId', true);
reader.enableArray('fieldData', 'labels', true);

Argument	Type	Required	Description
location	String	Yes
name	String	Yes
enable	Boolean	No

extend

Method used to decorate a given object (publicAPI+model) with vtkHttpDataSetReader characteristics.

Argument	Type	Required	Description
publicAPI		Yes	object on which methods will be bounds (public)
model		Yes	object on which data structure will be bounds (protected)
initialValues	IHttpDataSetReaderInitialValues	No	(default: {})

getArrays

Get the list of available array with their location and if they are enable or not for download using the update() method.

getArraysByReference

getBaseURL

Get the base url to use to download arrays or other data from the given dataset.

reader.setURL('/Data/can.ex2/index.json');

if (reader.getBaseURL() === '/Data/can.ex2') {
  console.log('Good guess...');
}

getCachedArrayIds

Gets an array of all cached array ids.

getDataAccessHelper

getEnableArray

getFetchGzip

getMaxCacheSize

Gets the maximum size cached arrays are allowed to occupy. Size is given in MiB. If cache size is exceeded, the arrays that where not accessed the longest are removed.

Special settings: -1 -> Cache unlimited 0 -> Cache disabled null -> Cache disabled undefined -> Cache disabled

getUrl

Get the url of the object to load.

invokeBusy

Argument	Type	Required	Description
busy	Boolean	Yes

isBusy

Get the current status of the reader. True means busy and False means idle.

loadData

newInstance

Method used to create a new instance of vtkHttpDataSetReader while enabling a default behavior regarding the data array and the way they should be fetched from the server.

The enableArray argument allow you to choose if you want to activate all data array by default or if you will have to manually enable them before downloading them.

Argument	Type	Required	Description
initialValues	IHttpDataSetReaderInitialValues	No	for pre-setting some of its content

onBusy

Attach listener to monitor when the reader is downloading data or not.

const subscription = reader.onBusy(busy => {
  console.log('Reader is', busy ? 'downloading' : 'idle');
})

reader.update();
// much later
subscription.unsubscribe();

Argument	Type	Required	Description
callback		Yes

parseObject

Set the dataset object to use for data fetching.

Argument	Type	Required	Description
manifest	IDatasetManifest	Yes	The dataset manifest object
options	IParseObjectOptions	Yes

requestData

Argument	Type	Required	Description
inData		Yes
outData		Yes

setDataAccessHelper

Argument	Type	Required	Description
dataAccessHelper		Yes

setMaxCacheSize

Sets the maximum size cached arrays are allowed to occupy. Size is given in MiB. If cache size is exceeded, the arrays that where not accessed the longest are removed. If set to "undefined" the cache is unlimited.

Special settings: -1 -> Cache unlimited 0 -> Cache disabled null -> Cache disabled undefined -> Cache disabled

setProgressCallback

Argument	Type	Required	Description
progressCallback		Yes

setUrl

Set the url for the dataset to load.

const reader = HttpDataSetReader.newInstance();
isReady = reader.setURL('/Data/can.ex2/index.json');

// Same as
const reader = HttpDataSetReader.newInstance({ url: '/Data/can.ex2/index.json' });
isReady = reader.updateMetadata();

Argument	Type	Required	Description
url	String	Yes	the url of the object to load.
option	IHttpDataSetReaderOptions	No	The Draco reader options.

updateMetadata