pynetdicom.dimse.DIMSEServiceProvider¶
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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
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message
¶ The DIMSE message.
Type: dimse_messages.DIMSEMessage
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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
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__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. -
assoc
¶ Return the ACSE’s Association.
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dimse_timeout
¶ Return the DIMSE timeout as numeric or None.
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dul
¶ Return the Association’s DUL service provider.
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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
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maximum_pdu_size
¶ Return the peer’s maximum PDU length.
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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
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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.
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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.