DICOM PS3.7 2019a - Message Exchange

D.3.3.3 Asynchronous Operations (And Sub-Operations) Window Negotiation

The Asynchronous Operations Window is used to negotiate the maximum number of outstanding operation or sub-operation requests (i.e., command requests) for each direction. The synchronous operations mode is the default mode and shall be supported by all DICOM AEs. This negotiation is optional.

The Association-requester conveys in the A-ASSOCIATE request:

A value of zero indicates that the above parameters are unlimited. A value of one indicates that there is no Asynchronous Operations support. If the Asynchronous Operations Window is absent the default for the above parameters shall be equal to one.

The Association-acceptor conveys in the A-ASSOCIATE response:

A value of zero indicates that the above parameters are unlimited. If the Asynchronous Operations Window is absent the default for the above parameters shall be equal to one. Figures D.3-5 and D.3-6 illustrate examples of Asynchronous Operations Window negotiation.

If this negotiation is not present in the A-ASSOCIATE indication it shall be omitted in the A-ASSOCIATE response.

Note

The case where the Association-requester offers the value of zero (which indicates unlimited operations), the Association-acceptor may return zero (agreeing to unlimited operations) or negotiate the parameter down by conveying a value other than zero.

Asynchronous Operations Window Negotiation (Window Being Negotiated Down By DICOM Application Entity "B")

Figure D.3-5. Asynchronous Operations Window Negotiation (Window Being Negotiated Down By DICOM Application Entity "B")


Asynchronous Operations Window Negotiation (Window Being Defaulted to 1, 1 By DICOM Application Entity "B")

Figure D.3-6. Asynchronous Operations Window Negotiation (Window Being Defaulted to 1, 1 By DICOM Application Entity "B")


D.3.3.3.1 Asynchronous Operations Window Sub-Item Structure (A-ASSOCIATE-RQ)

The Asynchronous Operations Window Sub-Item shall be made of a sequence of mandatory fixed length fields. This Sub-Item is optional and if supported, only one Asynchronous Operations Window Sub-Item shall be present in the User Data Item of the A-ASSOCIATE-RQ. Table D.3-7 shows the sequence of the mandatory fields.

Table D.3-7. Asynchronous Operations Window Sub-Item Fields (A-ASSOCIATE-RQ)

Item Bytes

Field Name

Description of Field

1

Item-type

53H

2

Reserved

This reserved field shall be sent with a value 00H but not tested to this value when received.

3 - 4

Item-length

This Item-length shall be the number of bytes from the first byte of the following field to the last byte of the Maximum-number-operations-performed field. In the case of this Sub-Item, it shall have the fixed value of 00000004H encoded as an unsigned binary number.

5 - 6

Maximum-number-operations-invoked

This field shall contain the Maximum-number-operations-invoked as defined for the Association-requester in Section D.3.3.3. It shall be encoded as an unsigned binary number.

7-8

Maximum-number-operations-performed

This field shall contain the Maximum-number-operations-performed as defined for the Association-requester in Section D.3.3.3. It shall be encoded as an unsigned binary number.


DICOM PS3.7 2019a - Message Exchange