PDU Types (pdu)

Module contains implementation of the DICOM Protocol Data Units (or PDU for short). Each PDU is represented by class that follows the simple interface that has only two methods:

  • encode - method that transforms PDU into raw byte string
  • decode - factory method that transforms raw byte string to PDU instance

In addition to PDUs, several items and sub-items classes can be found in this module. These classes are:

The rest sub-items for User Data Information Item can be found at User Data Sub-items (userdataitems).

class pynetdicom2.pdu.AAssociatePDUBase(called_ae_title, calling_ae_title, variable_items, protocol_version=1, reserved1=0, reserved2=0, reserved3=None)

Base class for A-ASSOCIATE-RQ and A-ASSOCIATE-AC PDUs

Variables:
  • called_ae_title – called AE Title (remote AET)
  • calling_ae_title – calling AE Title (local AET)
  • variable_items – list of various variable items
  • protocol_version – protocol version, should be 1
  • reserved1 – reserved field, defaults 0
  • reserved2 – reserved field, defaults 0
  • reserved3 – reserved field, defaults eight 0
pdu_length

PDU length without the header

Returns:PDU length
Return type:int
encode()

Encodes PDU into bytes

Returns:encoded PDU
Return type:bytes
classmethod decode(raw_bytes)

Factory method. Decodes A-ASSOCIATE-RQ PDU instance from raw string.

Parameters:raw_bytes – bytes containing binary representation of the A-ASSOCIATE-RQ PDU
Returns:decoded PDU
total_length()

Returns total PDU length including the header

Returns:total PDU length
Return type:int
class pynetdicom2.pdu.AAssociateRqPDU(called_ae_title, calling_ae_title, variable_items, protocol_version=1, reserved1=0, reserved2=0, reserved3=None)

This class represents the A-ASSOCIATE-RQ PDU

Refer to DICOM PS3.8 9.3.2 for A-ASSOCIATE-RQ structure and fields

pdu_type = 1

PDU Type

class pynetdicom2.pdu.AAssociateAcPDU(called_ae_title, calling_ae_title, variable_items, protocol_version=1, reserved1=0, reserved2=0, reserved3=None)

This class represents the A-ASSOCIATE-AC PDU

Refer to DICOM PS3.8 9.3.3 for A-ASSOCIATE-AC structure and fields

pdu_type = 2

PDU Type

class pynetdicom2.pdu.AAssociateRjPDU(result, source, reason_diag, reserved1=0, reserved2=0)

This class represents the A-ASSOCIATE-RJ PDU (PS 3.8 9.3.4)

You can look up possible values for fields in DICOM standard (referenced above) or in documentation for AssociationRejectedError

Variables:
  • result – Result PDU field. (unsigned byte)
  • source – Source PDU field (unsigned byte)
  • reason_diag – Reason/Diag. PDU field (unsigned byte)
  • reserved1 – Reserved field, defaults to 0 (unsigned byte)
  • reserved2 – Reserved field, defaults to 0 (unsigned byte)
pdu_type = 3

PDU Type

pdu_length = 4

This PDU has fixed length of 4 bytes

encode()

Converts PDU class to its binary representation

Returns:PDU as a string of bytes
classmethod decode(rawstring)

Factory method. Decodes A-ASSOCIATE-RJ PDU instance from raw string.

Parameters:rawstring – rawstring containing binary representation of the A-ASSOCIATE-RJ PDU
Returns:decoded PDU
static total_length()

Returns PDU total length.

This PDU has a fixed length of 10, so method always returns 10 regardless of specific instance

Returns:PDU total length
class pynetdicom2.pdu.PDataTfPDU(data_value_items, reserved=0)

This class represents the P-DATA-TF PDU (as described in PS 3.8 9.3.5).

Variables:
  • reserved – reserved field, defaults 0
  • data_value_items – list of one of more PresentationDataValueItem
pdu_type = 4

PDU Type

pdu_length

PDU length without the header

Returns:PDU length
Return type:int
encode()

Encodes PDataTfPDU into bytes

Returns:encoded PDU
Return type:bytes
classmethod decode(rawstring)

Factory method. Decodes P-DATA-TF PDU instance from raw string.

Parameters:rawstring – rawstring containing binary representation of the P-DATA-TF PDU
Returns:decoded PDU
total_length()

Returns total PDU length including the header

Returns:total PDU length
Return type:int
class pynetdicom2.pdu.AReleasePDUBase(reserved1=0, reserved2=0)

Base class for the A-RELEASE-* PDUs.

Variables:
  • reserved1 – reserved field, defaults 0
  • reserved2 – reserved field, defaults 0
pdu_length = 4

Association Release PDUs have fixed length of 4 bytes

encode()

Encodes PDU into bytes

Returns:encoded PDU
Return type:bytes
classmethod decode(rawstring)

Factory method. Decodes A-RELEASE-* PDU instance from raw string.

Parameters:rawstring – rawstring containing binary representation of the A-RELEASE-* PDU
Returns:decoded PDU
static total_length()

Returns PDU total length.

This PDU has a fixed length of 10, so method always returns 10 regardless of specific instance

Returns:PDU total length
class pynetdicom2.pdu.AReleaseRqPDU(reserved1=0, reserved2=0)

This class represents the A-RELEASE-RQ PDU as described in PS 3.8 9.3.6

pdu_type = 5

PDU Type

class pynetdicom2.pdu.AReleaseRpPDU(reserved1=0, reserved2=0)

This class represents the A-RELEASE-RP PDU as described in PS 3.8 9.3.7

pdu_type = 6

PDU Type

class pynetdicom2.pdu.AAbortPDU(source, reason_diag, reserved1=0, reserved2=0, reserved3=0)

This class represents the A-ABORT PDU as described in PS 3.8 9.3.8

Variables:
  • reserved1 – reserved field, defaults 0
  • reserved2 – reserved field, defaults 0
  • reserved3 – reserved field, defaults 0
  • reserved3 – reserved field, defaults 0
  • source –

    abort source:

    • 0 - DICOM UL service-user (initiated abort)
    • 1 - reserved
    • 2 - DICOM UL service-provider (initiated abort)
  • reason_diag –

    Reason/Diag. value:

    • 0 - reason-not-specified
    • 1 - unrecognized-PDU
    • 2 - unexpected-PDU
    • 3 - reserved
    • 4 - unrecognized-PDU parameter
    • 5 - unexpected-PDU parameter
    • 6 - invalid-PDU-parameter value
pdu_type = 7

PDU Type

pdu_length = 4

Association Abort PDU have fixed length of 4 bytes

encode()

Encodes AAbortPDU into bytes

Returns:encoded PDU
Return type:bytes
classmethod decode(rawstring)

Factory method. Decodes A-ABORT PDU instance from raw string.

Parameters:rawstring – rawstring containing binary representation of the A-ABORT PDU
Returns:decoded PDU
static total_length()

Returns PDU total length.

This PDU has a fixed length of 10, so method always returns 10 regardless of specific instance

Returns:PDU total length
class pynetdicom2.pdu.ApplicationContextItem(context_name, reserved=0)

Application Context Item (PS 3.8 9.3.2.1)

Variables:
  • reserved – reserved field, defaults 0
  • context_name – application context name (OID)
item_type = 16

PDU Item-type

item_length

Item length, excluding the header

Returns:item length
Return type:int
encode()

Encodes item into bytes

Returns:encoded item
Return type:bytes
classmethod decode(stream)

Decodes application context item from data stream

Parameters:stream – raw data stream
Returns:decoded item
total_length()

Total item length, including the header

Returns:total item length
Return type:int
class pynetdicom2.pdu.PresentationContextItemRQ(context_id, abs_sub_item, ts_sub_items, reserved1=0, reserved2=0, reserved3=0, reserved4=0)

Presentation Context Item (request) PS 3.8 9.3.2.2

Variables:
  • context_id – presentation context ID
  • abs_sub_item – Abstract Syntax sub-item
  • ts_sub_items – list of Transfer Syntax sub-items
  • reserved1 – reserved field, defaults 0
  • reserved2 – reserved field, defaults 0
  • reserved3 – reserved field, defaults 0
  • reserved4 – reserved field, defaults 0
item_type = 32

PDU Item-type

item_length

Item length, excluding the header

Returns:item length
Return type:int
encode()

Encodes item into bytes

Returns:encoded item
Return type:bytes
classmethod decode(stream)

Decodes presentation context item ‘request’ from data stream

Parameters:stream – raw data stream
Returns:decoded context item
total_length()

Total item length, including the header

Returns:total item length
Return type:int
class pynetdicom2.pdu.PresentationContextItemAC(context_id, result_reason, ts_sub_item, reserved1=0, reserved2=0, reserved3=0)

Presentation Context Item (response) PS 3.8 9.3.3.2

Variables:
  • context_id –
  • result_reason –

    result/reason, can be one of the following:

    • 0 - acceptance
    • 1 - user-rejection
    • 2 - no-reason (provider rejection)
    • 3 - abstract-syntax-not-supported (provider rejection)
    • 4 - transfer-syntaxes-not-supported (provider rejection)
  • ts_sub_item – list of Transfer Syntax sub-items
  • reserved1 – reserved field, defaults 0
  • reserved2 – reserved field, defaults 0
  • reserved3 – reserved field, defaults 0
item_type = 33

PDU Item-type

item_length

Item length, excluding the header

Returns:item length
Return type:int
encode()

Encodes item into bytes

Returns:encoded item
Return type:bytes
classmethod decode(stream)

Decodes presentation context item ‘accepted’ from data stream

Parameters:stream – raw data stream
Returns:decoded context item
total_length()

Total item length, including the header

Returns:total item length
Return type:int
class pynetdicom2.pdu.AbstractSyntaxSubItem(name, reserved=0)

Abstract Syntax Sub-Item (PS 3.8 9.3.2.2.1)

Variables:
  • name – Abstract Syntax name (UID) as byte string
  • reserved – reserved field. In most cases value should be default (0x00). Standard advises against testing this field value.
item_type = 48

Item type

item_length

Item length, excluding the header

Returns:item length
Return type:int
encode()

Encodes item into bytes

Returns:encoded item
Return type:bytes
classmethod decode(stream)

Decodes abstract syntax sub-item from data stream

Parameters:stream – raw data stream
Returns:decoded abstract syntax sub-item
total_length()

Total item length, including the header

Returns:total item length
Return type:int
class pynetdicom2.pdu.TransferSyntaxSubItem(name, reserved=0)

Transfer Syntax Sub-Item (PS 3.8 9.3.2.2.2)

Variables:
  • name – Transfer Syntax name (UID) as byte string
  • reserved – reserved field. In most cases value should be default (0x00). Standard advises against testing this field value.
item_type = 64

Item type

item_length

Item length, excluding the header

Returns:item length
Return type:int
encode()

Encodes item into bytes

Returns:encoded item
Return type:bytes
classmethod decode(stream)

Decodes transfer syntax sub-item from data stream

Parameters:stream – raw data stream
Returns:decoded transfer syntax sub-item
total_length()

Total item length, including the header

Returns:total item length
Return type:int
class pynetdicom2.pdu.UserInformationItem(user_data, reserved=0)

User Information Item (PS 3.8 9.3.2.3)

Variables:
  • reserved – reserved field. In most cases value should be default (0x00). Standard advises against testing this field value.
  • user_data –

    list containing the following:
item_length

Item length, excluding the header

Returns:item length
Return type:int
encode()

Encodes item into bytes

Returns:encoded item
Return type:bytes
static sub_items(stream)

Reads User Information sub-items from a data stream

Parameters:stream (IO[bytes]) – raw data stream
Raises:exceptions.PDUProcessingError – [description]
Yield:User Information sub-item
classmethod decode(stream)

Decodes user information item from data stream

Parameters:stream – raw data stream
Returns:decoded user information item
total_length()

Total item length, including the header

Returns:total item length
Return type:int
class pynetdicom2.pdu.PresentationDataValueItem(context_id, data_value)

Presentation Data Value Item (PS 3.8 9.3.5.1)

Variables:
  • context_id – presentation context ID
  • data_value – item value (bytes)
item_length

Item length, excluding the header

Returns:item length
Return type:int
encode()

Encodes item into bytes

Returns:encoded item
Return type:bytes
classmethod decode(stream)

Decodes presentation data value item from data stream

Presentation data value is left in raw string format. The Application Entity is responsible for dealing with it.

Parameters:stream – raw data stream
Returns:decoded presentation data value item
total_length()

Total item length, including the header

Returns:total item length
Return type:int