DICOM PS3.7 2020c - Message Exchange

7.2 DIMSE Service User Interaction (Current)
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## 7.2 DIMSE Service User Interaction

The DICOM Message Service Element receives notification and operation requests and their related information from the DIMSE Service User. Two DICOM Application Entities take the roles as peer DIMSE Service Users in order to exchange notifications and operations.

A notification or operation is implemented as a request/response interaction carried out within the context of an established application Association. Typically, one DIMSE Service User requests that a particular operation be performed (or notification be processed) and the other DIMSE Service User attempts to perform the operation (or process the notification) and then reports the outcome of the attempt.

When engaging in the operations or notifications, the DIMSE Service User takes on one of two roles:

1. it performs operations (on SOP Instances for which it has responsibility) that were invoked by a peer DIMSE Service User. It may also emit change-of-state notifications for SOP Instances to one or more peer DIMSE Service Users. These notifications may be invoked as a result of operations initiated by other DIMSE Service Users.

2. it invokes the performance of an operation on a peer DIMSE Service User. It may also receive notifications from a peer DIMSE Service User.

These roles are depicted in Figure 7.2-1.

### Note

1. Role a) (called the Agent role in ISO terminology) is used by an implementation that conforms to a DICOM Service Class as an SCP.

2. Role b) (called the Manager role in ISO terminology) is used by an implementation that conforms to a DICOM Service Class as an SCU.

Figure 7.2-1. Operation and Notification Flow

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DICOM PS3.7 2020c - Message Exchange