Loading data from a Table

Data can be loaded into <perspective-viewer> in the form of a Table() or a Promise<Table> via the load() method.

// Create a new worker, then a new table promise on that worker.
const worker = await perspective.worker();
const table = await worker.table(data);

// Bind a viewer element to this table.
await viewer.load(table);

Sharing a Table between multiple <perspective-viewer>s

Multiple <perspective-viewer>s can share a table() by passing the table() into the load() method of each viewer. Each perspective-viewer will update when the underlying table() is updated, but table.delete() will fail until all perspective-viewer instances referencing it are also deleted:

const viewer1 = document.getElementById("viewer1");
const viewer2 = document.getElementById("viewer2");

// Create a new WebWorker
const worker = await perspective.worker();

// Create a table in this worker
const table = await worker.table(data);

// Load the same table in 2 different <perspective-viewer> elements
await viewer1.load(table);
await viewer2.load(table);

// Both `viewer1` and `viewer2` will reflect this update
await table.update([{ x: 5, y: "e", z: true }]);

Loading from a virtual Table

Loading a virtual (server-only) Table works just like loading a local/Web Worker Table — just pass the virtual Table to viewer.load(). In the browser:

const elem = document.getElementsByTagName("perspective-viewer")[0];

// Bind to the server's worker instead of instantiating a Web Worker.
const websocket = await perspective.websocket(
    window.location.origin.replace("http", "ws")
);

// Bind the viewer to the preloaded data source.  `table` and `view` objects
// live on the server.
const server_table = await websocket.open_table("table_one");
await elem.load(server_table);

Alternatively, data can be cloned from a server-side virtual Table into a client-side WebAssembly Table. The browser clone will be synced via delta updates transferred via Apache Arrow IPC format, but local Views created will be calculated locally on the client browser.

const worker = await perspective.worker();
const server_view = await server_table.view();
const client_table = worker.table(server_view);
await elem.load(client_table);

<perspective-viewer> instances bound in this way are otherwise no different than <perspective-viewer>s which rely on a Web Worker, and can even share a host application with Web Worker-bound table()s. The same promise-based API is used to communicate with the server-instantiated view(), only in this case it is over a websocket.