Fetching Events

There are several methods to fetch events exposed by the Metastream client. All of them, among other arguments, require a context and the event type needs to be retrieved. The whole list of supported event types can be retrieved using the fetch_event_types method shown in section Fetch Event Types. The context shown in Metastream Context is used to store specific session wide data such as metrics, checkpoint and the time window of historical data to be retrieved.

Metastream Context

The context used by the Metastream client provides information about what was already retrieved and what needs to be retrieved as well as some statistic information. It holds three pieces of information:

Attribute	Type	Description
checkpoint	string	The value contained in the checkpoint, was the end_date in the last performed search. It must be used as the start date for the next call of the fetching method. The checkpoint is updated every time the fetching method is called.
history	dictionary	The FncClient Library allows you to pull historical data when fetching events. However, it is possible that the amount of historical information is too big that it causes delays on the retrieval of current data. To avoid this delay, the client library allows you to split the context in historical and current data. This way current data and historical data can be retrieved separately.
api_calls, file_downloads	int	While fetching events, the statistical information of the number of API calls and downloaded files is updated in the context.

Splitting Historical and Current Data

The client library provides a method (get_splitted_context) that provide two context one with the history value set to pull data from the provided start_date up to now and a second one without history value and the checkpoint set to now. In this way we can pull the historical data using the first context while pulling the current data using the second one.

Example:

# Split the poling interval in history and current
h_context, context = client.get_splitted_context(start_date_str = <start_date of the history>)

Fetch Event Types

The fetch_event_types() method can be used to retrieve a list of supported event types. This function does not receive any argument and return a list of strings in which every element is an event type.

Example:

The code below will print the list of supported event types.

from fnc.metastream import FncMetastreamClient
from fnc.errors import FncClientError
from fnc.fnc_client import FncClient

client_name = ''
access_key = ''
secret_key = ''
account_code = ''
bucket_name = ''
log_level = None

try: 
    client: FncMetastreamClient = FncClient.get_metastream_client(
      name= client_name, 
      access_key= access_key, 
      secret_key= secret_key, 
      account_code = account_code, 
      bucket_name= bucket_name
    ) 

    client.get_logger().set_level(level=log_level) 

     print(f'The supported event types are: {client.fetch_event_types()}') 

except FncClientError as e: 
    client.get_logger().error(e)