congress.dse2.data_service module¶

class congress.dse2.data_service.DataService(service_id)¶

Bases: object

A unit of data and business logic that interfaces with the DSE.

A DataService may publish tables, subscribe to tables, and/or expose RPCs on the DSE. DataService instances are bound to a DseNode which is used for all inter-service communication.

Attributes:

• service_id: A unique ID of the service.
• _published_tables_with_subscriber: A set of tables published by self that has subscribers

add_rpc_endpoint(endpt)¶

check_resub_all()¶

Check all subscriptions for long missing update and resubscribe.

get_datasource(datasource_id)¶

get_datasources(filter_secret=False)¶

get_driver_info(*args)¶

get_driver_schema(*args)¶

get_drivers_info(*args)¶

get_last_published_data_with_seqnum(table)¶

Method that returns the current seqnum & data for given table.

get_snapshot(table)¶

Method that returns the current data for the given table.

Should be overridden.

info¶

is_valid_service(service_id)¶

make_datasource_dict(*args, **kwargs)¶

publish(table, data, use_snapshot=False)¶

receive_data(publisher, table, data, is_snapshot=True)¶

Method called when publication data arrives.

Instances will override this method.

receive_data_sequenced(publisher, table, data, seqnum, is_snapshot=False, receipt_time=None)¶

Method called when sequenced publication data arrives.

rpc(service, action, kwargs=None, timeout=None, local=False, retry=None)¶

rpc_endpoints()¶

Return list of RPC endpoint objects to be exposed for this service.

A DataService may include zero or more RPC endpoints to be exposed by the DseNode. Each endpoint object must be compatible with the oslo.messaging RPC Server.

start()¶

Start the DataService.

This method is called by a DseNode before any RPCs are invoked.

status¶

stop()¶

Stop the DataService.

This method is called by a DseNode when the DataService instance is no longer needed. No RPCs will invoked on stopped DataServices.

subscribe(service, table)¶

subscriber_list()¶

Method that returns subscribers list.

It returns list of services subscribed to this service data.

subscription_list()¶

Method that returns subscription list.

It returns list of tuple that represents the service’s subscription. The tuple forms following format: (service_id, table_name).

unsubscribe(service, table)¶

wait()¶

Wait for processing to complete.

After a call to stop(), the DataService may have some outstanding work that has not yet completed. The wait() method blocks until all DataService processing is complete.

class congress.dse2.data_service.DataServiceEndPoints(service)¶

Bases: object

get_last_published_data_with_seqnum(context, table)¶

Function called on a node when an RPC request is sent.

get_snapshot(context, table)¶

Function called on a node when an RPC request is sent.

ping(client_ctxt, **args)¶

Echo args

class congress.dse2.data_service.DataServiceInfo(service_id=None, node_id=None, published_tables=None, subscribed_tables=None, rpc_endpoints_info=None)¶

Bases: object

Metadata for DataService on the DSE.

Attributes: - service_id: The ID of the service. - node_id: The ID of the node the service is running on. - published_tables: List of table IDs published by this service. - subscribed_tables: List of table IDs this service subscribes to. - rpc_endpoints_info: List of RPC endpoints exposed by this service.

MARSHALL_ATTRS = {'node_id', 'published_tables', 'rpc_endpoints_info', 'service_id', 'subscribed_tables'}¶

classmethod from_dict(raw_dict)¶

classmethod from_json(json_string)¶

to_dict()¶

to_json()¶