blpapi.SubscriptionList

class blpapi.SubscriptionList

A list of subscriptions.

Contains a list of subscriptions used when subscribing and unsubscribing.

A SubscriptionList is used when calling Session.subscribe(), Session.resubscribe() and Session.unsubscribe(). The entries can be constructed in a variety of ways.

The two important elements when creating a subscription are:

• Subscription string: A subscription string represents a topic whose updates user is interested in.

• CorrelationId: the unique identifier to tag all data associated with this subscription.

The following table describes how various operations use the above elements:

OPERATION	SUBSCRIPTION STRING	CORRELATION ID
subscribe	Used to specify the topic to subscribe to.	Identifier for the subscription. If uninitialized correlationid was specified an internally generated correlationId will be set for the subscription.
resubscribe	Used to specify the new topic to which the subscription should be modified to.	Identifier of the subscription which needs to be modified.
unsubscribe	NOT USED	Identifier of the subscription which needs to be canceled.

__init__()

Create an empty SubscriptionList.

add(topic, fields=None, options=None, correlationId=None)

Add the specified topic to this SubscriptionList.

Parameters:

• topic (Optional[str]) – The topic to subscribe to

• fields (Union[str, Sequence[str], None]) – List of fields to subscribe to

• options (Union[str, Sequence[str], Mapping, None]) – List of options

• correlationId (Optional[CorrelationId]) – Correlation id to associate with the subscription

Add the specified topic, with the optionally specified fields and the options to this SubscriptionList, associating the optionally specified correlationId with it. The fields must be represented as a comma separated string or a list of strings, options - as an ampersand separated string or list of strings or a name -> value dictionary.

Return type:

int

Note

In case of unsubscribe, you can pass empty string or None for topic.

addResolved(subscriptionString, correlationId=None)

Parameters:

• subscriptionString (str) – Fully-resolved subscription string

• correlationId (Optional[CorrelationId]) – Correlation id to associate with the subscription

Add the specified subscriptionString to this SubscriptionList object, associating the specified correlationId with it. The subscription string may include options. The behavior of this function, and of functions operating on this SubscriptionList object, is undefined unless subscriptionString is a fully-resolved subscription string; clients that cannot provide fully-resolved subscription strings should use add() instead.

Return type:

int

Note

It is at the discretion of each function operating on a SubscriptionList whether to perform resolution on this subscription.

append(other)

Append a copy of the specified SubscriptionList to this list.

Parameters:

other – List to append to this one

clear()

Remove all entries from this object.

Return type:

int

correlationIdAt(index)

Parameters:

index (int) – Index of the entry in the list

Return type:

CorrelationId

Returns:

Correlation id of the indexth entry.

Raises:

Exception – If index >= size().

destroy()

Destroy the handle using stored dtor

Return type:

None

isResolvedTopicAt(index)

Parameters:

index (int) – Index of the entry in the list

Return type:

bool

Returns:

True if the index``th entry in this ``SubscriptionList object was created using addResolved() and False if it was created using add(). An exception is thrown if index >= size().

size()

Return type:

int

Returns:

The number of subscriptions in this object.

topicStringAt(index)

Parameters:

index (int) – Index of the entry in the list

Return type:

str

Returns:

The full topic string at the specified index.

Raises:

Exception – If index >= size().