pynetdicom.dimse.DIMSEServiceProvider

class pynetdicom.dimse.DIMSEServiceProvider(assoc)

The DIMSE service provider.

A DICOM AE uses the services provided by the DICOM Message Service Element (DIMSE). DIMSE specifies two sets of services.

  • DIMSE-C supports operations associated with composite SOP Classes and provides effective compatibility with the previous versions of the DICOM standards.

  • DIMSE-N supports operations associated with normalised SOP Classes and provides an extended set of object-orientated operations and notifications

Service Overview

The DIMSE service provider supports communication between peer DIMSE service users. A service user acts in one of two roles:

  • invoking DIMSE user

  • performing DIMSE user

Service users make use of service primitives provided by the DIMSE service provider. A service primitive shall be one of the following types:

  • request primitive

  • indication primitive

  • response primitive

  • confirmation primitive

These primitives are used as follows:

  • The invoking service user issues a request primitive to the DIMSE provider

  • The DIMSE provider receives the request primitive and issues an indication primitive to the performing service user

  • The performing service user receives the indication primitive and performs the requested service

  • The performing service user issues a response primitive to the DIMSE provider

  • The DIMSE provider receives the response primitive and issues a confirmation primitive to the invoking service user

  • The invoking service user receives the confirmation primitive, completing the DIMSE service.

Service Primitive Classes

  • DIMSE-C: C_ECHO, C_STORE, C_GET, C_FIND, C_MOVE

  • DIMSE-N: N_EVENT_REPORT, N_GET, N_GET, N_ACTION, N_CREATE, N_DELETE

Protocol Machine

PS3.7 8.1 The DIMSE protocol machine defines the procedures and the encoding rules necessary to construct Messages used to exchange command requests and responses between peer DIMSE service users.

The DIMSE protocol machine accepts service user requests and response service primitives and constructs Messages defined by the procedures in PS3.7 9.3 and 10.3. The DIMSE protocol machine accepts Messages and passes them to the DIMSE service user by the means of indication and confirmation service primitives.

Messages

Primitive

Type

Message Class

C-CANCEL

Request/indication

C_CANCEL_R

C-ECHO

Request/indication

C_ECHO_RQ

Response/confirmation

C_ECHO_RSP

C-FIND

Request/indication

C_FIND_RQ

Response/confirmation

C_FIND_RSP

C-GET

Request/indication

C_GET_RQ

Response/confirmation

C_GET_RSP

C-MOVE

Request/indication

C_MOVE_RQ

Response/confirmation

C_MOVE_RSP

C-STORE

Request/indication

C_STORE_RQ

Response/confirmation

C_STORE_RSP

N-ACTION

Request/indication

N_ACTION_RQ

Response/confirmation

N_ACTION_RSP

N-CREATE

Request/indication

N_CREATE_RQ

Response/confirmation

N_CREATE_RSP

N-DELETE

Request/indication

N_DELETE_RQ

Response/confirmation

N_DELETE_RSP

N-EVENT-REPORT

Request/indication

N_EVENT_REPORT_RQ

Response/confirmation

N_EVENT_REPORT_RSP

N-GET

Request/indication

N_GET_RQ

Response/confirmation

N_GET_RSP

N-SET

Request/indication

N_SET_RQ

Response/confirmation

N_SET_RSP

cancel_rq

A dict of {MessageIDBeingRespondedTo : C_CANCEL} messages received. The dict is cleared out at the start and end of Service Class operations and is limited to a maximum of 10 messages.

Type

dict

message

The DIMSE message.

Type

dimse_messages.DIMSEMessage

msg_queue

A queue holding decoded DIMSE Message primitives received from the peer, except for C-CANCEL requests.

Type

queue.queue of dimse_messages.DIMSEMessage

References

  • DICOM Standard, Part 7

__init__(assoc)

Initialise the DIMSE service provider.

Parameters

assoc (association.Association) – The Association to provide DIMSE services for.

Methods

__init__(assoc)

Initialise the DIMSE service provider.

get_msg([block])

Get the next available DIMSE message.

peek_msg()

Return the first message in the message queue or None.

receive_primitive(primitive)

Process a P-DATA primitive received from the remote.

send_msg(primitive, context_id)

Send a DIMSE-C or DIMSE-N message to the peer AE.

Attributes

assoc

Return the ACSE’s Association.

dimse_timeout

Return the DIMSE timeout as numeric or None.

dul

Return the Association’s DUL service provider.

maximum_pdu_size

Return the peer’s maximum PDU length.

property assoc

Return the ACSE’s Association.

property dimse_timeout

Return the DIMSE timeout as numeric or None.

property dul

Return the Association’s DUL service provider.

get_msg(block=False)

Get the next available DIMSE message.

Parameters

block (bool) – If True then the function will block until either a message is available or dimse_timeout expires, otherwise non-blocking.

Returns

The next available (context ID, DIMSE message), which is taken off the queue, or (None, None) if no messages are available within the dimse_timeout period.

Return type

int, dimse_messages.DIMSEMessage or None, None

property maximum_pdu_size

Return the peer’s maximum PDU length.

peek_msg()

Return the first message in the message queue or None.

Returns

The first (context ID, message) in the queue if one is available, otherwise (None, None). No messages are taken out of the queue.

Return type

int, dimse_messages.DIMSEMessage or None, None

receive_primitive(primitive)

Process a P-DATA primitive received from the remote.

A DIMSE message is split into one or more P-DATA primitives, which must be sent in sequential order. While waiting for all the P-DATA primitives associated with a message the encoded data is stored in self.message, which is decoded only when complete and converted into a DIMSE Message primitive which is added to the msg_queue.

This makes it possible to process incoming P-DATA primitives into DIMSE messages while a service class implementation is running.

Parameters

primitive (pdu_primitives.P_DATA) – A P-DATA primitive received from the peer to be processed.

send_msg(primitive, context_id)

Send a DIMSE-C or DIMSE-N message to the peer AE.

Parameters
  • primitive (dimse_primitives DIMSE Primitive class) – The DIMSE message primitive to send to the peer.

  • context_id (int) – The ID of the presentation context that the message is to be sent under.