snapshot

The snapshot method returns a snapshot of a published remote table that matches the specified ticket.

note

If the remote table is closed or its owner session is closed, the ticket becomes invalid. If the same ticket is snapshot multiple times, multiple snapshots will be created.

Syntax

snapshot(ticket: bytes) -> Table

Parameters

Parameter	Type	Description
ticket	bytes	The bytes of the ticket.

Returns

A Table that is a snapshot of the remote table.

Examples

The following example installs the Deephaven Python Client (pydeephaven) and creates a remote Deephaven server running on our local machine on port 9999 with anonymous authentication. Next, the remote server is used to create a table and a shared ticket pointing to the table that can be shared with other sessions. Finally, a Barrage session is started that listens to the same server at port 9999, and a snapshot of the shared ticket's table is obtained.

import os

os.system("pip install pydeephaven")
from deephaven.barrage import barrage_session
from pydeephaven.session import SharedTicket
from pydeephaven import Session

# Create a client session connected to the server running on port 9999
client_session = Session(host="host.docker.internal", port=9999)
# Create a table on that server with the client session
client_table = client_session.empty_table(10).update(["X = i"])
# Create a ticket through which `client_table` can be published
client_ticket = SharedTicket.random_ticket()
# Publish the ticket (table)
client_session.publish_table(client_ticket, client_table)

# Create a barrage session that listens to the server on port 9999
my_barrage_session = barrage_session(host="host.docker.internal", port=9999)
# Subscribe to the client table ticking data
local_table = my_barrage_session.snapshot(client_ticket.bytes)
# Perform operations on this now-local table
new_local_table = local_table.where("X > 5")

The following `docker-compose.yml` file was used to run the above code block. It starts two Deephaven servers: one running on port `10000` and the other on port `9999`. The code block was run from the server running on port `10000`.

services:
  deephaven1:
    image: ghcr.io/deephaven/server:latest
    ports:
      - 10000:10000
    volumes:
      - ./data:/data
    environment:
      - START_OPTS=-Xmx4g -DAuthHandlers=io.deephaven.auth.AnonymousAuthenticationHandler

  deephaven2:
    image: ghcr.io/deephaven/server:latest
    ports:
      - 9999:10000
    volumes:
      - ./data:/data
    environment:
      - START_OPTS=-Xmx4g -DAuthHandlers=io.deephaven.auth.AnonymousAuthenticationHandler

Related documentation

• Pydoc