blpapi.CorrelationId

class blpapi.CorrelationId(*argv, **_kwargs)

A key used to identify individual subscriptions or requests.

Two CorrelationId objects are considered equal if they have the same type() and:

If the type is UNSET_TYPE, then the two CorrelationId objects are always equal (as the value of both will necessarily be None).

It is possible that a user constructed CorrelationId and a CorrelationId generated by the API could return the same result for value(). However, they will not compare equal because they have a different type().

CorrelationId objects are passed to many of the Session object methods which initiate asynchronous operations and are obtained from Message objects which are delivered as a result of those asynchronous operations.

When subscribing or requesting information, an application has the choice of providing a CorrelationId they construct themselves or allowing the session to construct one for them. If the application supplies a CorrelationId, it must not re-use the value contained in it in another CorrelationId, whilst the original request or subscription is still active.

The xxx_TYPE class attributes represent the possible types of CorrelationId.

AUTOGEN_TYPE = 3

The CorrelationId was created internally by API.

INT_TYPE = 1

The CorrelationId was created from an int or long supplied by the user.

MAX_CLASS_ID = 65535

The maximum value allowed for classId.

OBJECT_TYPE = 2

The CorrelationId was created from an object supplied by the user.

STRUCT_SZ = 56
UNSET_TYPE = 0

The CorrelationId is unset. That is, it was created by the default CorrelationId constructor.

__init__(*argv, **_kwargs)

CorrelationId([value[, classId=0]]) constructs a CorrelationId object. If value is an integer (either int or long) then the created CorrelationId will have type INT_TYPE. Otherwise, it will have type OBJECT_TYPE. If no arguments are specified, then the type will be UNSET_TYPE. The maximum allowed classId value is MAX_CLASS_ID.

static cidFromCPtr(ptr)
Return type:

CorrelationId

classId()
Returns:

The user defined classification of this CorrelationId object

Return type:

int

type()
Returns:

The type of this CorrelationId object (see the xxx_TYPE class attributes)

Return type:

int

value()
Returns:

The value of this CorrelationId object.

Return type:

int or long or object

The return value depends on this CorrelationId’s value type and could be:

  • Integer (type() == CorrelationId.INT_TYPE or type() == CorrelationId.AUTOGEN_TYPE)

  • Object (type() == CorrelationId.OBJECT_TYPE)

  • None (type() == CorrelationId.UNSET_TYPE)