The get_traffic node of the response packet is structured as follows:

It wraps the result of the requested get_traffic operation. It can be missing if some error occurs before the validation starts. Data type: resultFilterType (common.xsd).
It returns the execution status of the get_traffic operation. Data type: string. Allowed values: ok | error.
It is used to return an error code if the get_traffic operation fails. Data type: unsignedInt.
Can be used to return an error message if the get_traffic operation fails. Data type: string.
It is always present and used to return the parameter by which the subscription was filtered by in the request packet. Data type: anySimple.
Returns the identifier of the subscription whose traffic is requested. It is missing if the request packet fails before the validation on the server side. Data type: integer.
It contains a collection of traffic data obtained from Plesk server (see below). Data type: trafficType (plesk_domain.xsd).
The traffic, defined by type trafficType (plesk_domain.xsd). It is structured as follows:

It specifies the date for which the traffic is shown. Data type: date. Format: YYYY-MM-DD.
It shows the incoming traffic (in bytes) got via HTTP protocol. Data type: integer.
It shows the outgoing HTTP traffic (in bytes). Data type: integer.
It shows the incoming traffic (in bytes) got via FTP protocol. Data type: integer.
It shows the outgoing FTP traffic (in bytes). Data type: integer.
It shows the incoming traffic (in bytes) got via SMTP protocol. Data type: integer.
It shows the outgoing SMTP traffic (in bytes). Data type: integer.
It shows the incoming traffic (in bytes) got via POP3 and IMAP protocols. Data type: integer.
It shows the outgoing POP3/IMAP traffic (in bytes). Data type: integer.