pynetdicom.pdu.PresentationDataValueItem

class pynetdicom.pdu.PresentationDataValueItem

A Presentation Data Value Item.

Presentation Data Value (PDV) Items are used to contain DIMSE Messages that have been fragmented into Command and Data fragments [1], with each fragment placed into its own PDV Item.

item_length

The Item Length field value.

Type:int

presentation_context_id

The Presentation Context ID field value.

Type:int

presentation_data_value

The Presentation Data Value field value.

Type:bytes

Notes

A Presentation Data Value Item requires the following parameters:

• Item length (1)
• Presentation context ID (1)
• Presentation data value (1)

Encoding

When encoded, a Presentation Data Value Item has the following structure, taken from Tables 9.24 [2] (offsets shown with Python indexing). Items are always encoded using Big Endian [3].

Offset	Length	Description
0	4	Item length
4	1	Presentation context ID
5	Variable	Presentation data value

References

[1]	DICOM Standard, Part 8, Annex E

[2]	DICOM Standard, Part 8, Section 9.3.5.1

[3]	DICOM Standard, Part 8, Section 9.3.1

__init__()

Initialise a new Presentation Data Value Item.

Methods

__init__()	Initialise a new Presentation Data Value Item.
decode(bytestream)	Decode bytestream and use the result to set the field values of the PDU item.
encode()	Return the encoded PDU as bytes.

Attributes

context_id	Return the item’s Presentation Context ID field value.
data	Return the item’s Presentation Data Value field value.
item_length	Return the item’s Item Length field value as an int.
item_type	Raise NotImplementedError as Presentation Data Value Items have no Item Type field.
message_control_header_byte	Return the message control header byte as a formatted string.

context_id

Return the item’s Presentation Context ID field value.

data

Return the item’s Presentation Data Value field value.

decode(bytestream)

Decode bytestream and use the result to set the field values of the PDU item.

Parameters:bytestream (bytes) – The PDU data to be decoded.

encode()

Return the encoded PDU as bytes.

Returns:The encoded PDU. Return type:bytes

item_length

Return the item’s Item Length field value as an int.

item_type

Raise NotImplementedError as Presentation Data Value Items have no Item Type field.

message_control_header_byte

Return the message control header byte as a formatted string.