pynetdicom.presentation.PresentationContext

class pynetdicom.presentation.PresentationContext[source]

A Presentation Context primitive.

Rules

  • Each Presentation Context (request) contains:

    • One context ID, an odd integer between 1 and 255.

    • One abstract syntax.

    • One or more transfer syntaxes.

  • Each Presentation Context (response) contains:

    • One context ID, corresponding to a Presentation Context received from the Requestor

    • A result, one of 0x00 (acceptance), 0x01 (user rejection), 0x02 (provider rejection), 0x03 (abstract syntax not supported) or 0x04 (transfer syntaxes not supported).

    • If the result is 0x00, then a transfer syntax.

    • If any other result, then a transfer syntax may or may not be present.

  • If the result is not 0x00 then the transfer syntax in the reply is not significant.

  • The same abstract syntax can be present in more than one Presententation Context.

  • Only one transfer syntax can be accepted per Presentation Context.

  • The Presentation Contexts may be sent by the Requestor in any order.

  • The Presentation Contexts may be sent by the Acceptor in any order.

SCP/SCU Role Selection Negotiation

  • If no role selection negotiation then the Requestor is SCU and the Acceptor is SCP

  • The association Acceptor cannot accept a role that has not been proposed (i.e. cannot return 1 when the proposed value is 0).

  • The association Requestor may be SCP only, SCU only or both SCU and SCP.

Requestor

Acceptor

Outcome

Notes

scu_role

scp_role

scu_role

scp_role

Req.

Acc.

N/A

N/A

N/A

N/A

SCU

SCP

Default

True

True

False

False

N/A

N/A

Rejected

True

SCP

SCU

True

False

SCU

SCP

Default

True

SCU/SCP

SCU/SCP

True

False

False

False

N/A

N/A

Rejected

True

SCU

SCP

Default

False

True

False

False

N/A

N/A

Rejected

True

SCP

SCU

False

False

False

False

N/A

N/A

Rejected

As can be seen from the above table there are four possible outcomes:

  • Requestor is SCU, Acceptor is SCP (default roles)

  • Requestor is SCP, Acceptor is SCU

  • Requestor and Acceptor are both SCU/SCP

  • Requestor and Acceptor are neither (context rejected)

abstract_syntax

The context’s Abstract Syntax.

Type

pydicom.uid.UID or None

as_scp

If True then the association Acceptor can act as SCP for the current context, otherwise it cannot. A non-None value is only available after association negotiation has been completed.

Type

bool or None

as_scu

If True then the association Acceptor can act as SCU for the current context, otherwise it cannot. A non-None value is only available after association negotiation has been completed.

Type

bool or None

context_id

The context’s Context ID.

Type

int or None

result

If part of an A-ASSOCIATE (request) then None. If part of an A-ASSOCIATE (response) then one of 0x00, 0x01, 0x02, 0x03, 0x04.

Type

int or None

scp_role

Only used when acting as an association Acceptor. If True then accept when the SCP role is proposed by the Requestor, otherwise reject the proposal. If None (default) then no SCP/SCU Role Selection reply will be sent and the default roles will be used.

Type

bool or None

scu_role

Only used when acting as an association Acceptor. If True then accept when the SCU role is proposed by the Requestor, otherwise reject the proposal. If None (default) then no SCP/SCU Role Selection reply will be sent and the default roles will be used.

Type

bool

transfer_syntax

The context’s Transfer Syntax(es).

Type

list of pydicom.uid.UID

References

__init__()[source]

Create a new object.

Methods

__init__()

Create a new object.

add_transfer_syntax(syntax)

Append a transfer syntax to the presentation context.

Attributes

abstract_syntax

Return the context’s Abstract Syntax as UID.

as_scp

Return True if can act as an SCP for the context.

as_scu

Return True if can act as an SCU for the context.

as_tuple

Return a namedtuple representation of the presentation context.

context_id

Return the context’s ID parameter as an int.

scp_role

Return True if a proposed SCP role will be accepted.

scu_role

Return True if a proposed SCU role will be accepted.

status

Return a descriptive str of the context’s Result.

transfer_syntax

Return the context’s Transfer Syntaxes as a list.
property abstract_syntax

Return the context’s Abstract Syntax as UID.

Returns

Return type

pydicom.uid.UID

add_transfer_syntax(syntax)[source]

Append a transfer syntax to the presentation context.

Parameters

syntax (pydicom.uid.UID, bytes or str) – The transfer syntax to add to the presentation context.

property as_scp

Return True if can act as an SCP for the context.

property as_scu

Return True if can act as an SCU for the context.

property as_tuple

Return a namedtuple representation of the presentation context.

Intended to be used when the result is 0x00 (accepted) as only the first transfer syntax item is returned in the tuple.

Returns

A representation of an accepted presentation context.

Return type

PresentationContextTuple

property context_id

Return the context’s ID parameter as an int.

property scp_role

Return True if a proposed SCP role will be accepted.

property scu_role

Return True if a proposed SCU role will be accepted.

property status

Return a descriptive str of the context’s Result.

Returns

The string representation of the negotiated result.

Return type

str

property transfer_syntax

Return the context’s Transfer Syntaxes as a list.

Returns

The context’s transfer syntaxes.

Return type

list of pydicom.uid.UID