7.4 Association Services
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## 7.4 Association Services

The DICOM Message Service Element does not provide separate services for the establishment and termination of application Associations. This section provides an overview of how an Application Entity using the DIMSE service uses the Association Services defined in PS3.8.

During the Association establishment phase, a DIMSE-service-user shall exchange initialization information using parameters of the A-ASSOCIATE Upper Layer Service (see Figure 7.4-1) that include:

- Application context

- Presentation and session requirements

- DIMSE-specific user information

- Application Association Information

The A-RELEASE and A-ABORT Services defined in PS3.8 shall be used for the termination of an Association.

### Note

The rules defining how the Association Services are used by a DIMSE-service-user are defined in Annex D.

### 7.4.1 Association Establishment

The A-ASSOCIATE Service is invoked by a DIMSE-service-user to establish an Association with a peer DIMSE-service-user. Association establishment is always the first phase of DICOM Message Exchange.

The initiating DIMSE-service-user and the responding DIMSE-service-user shall include Application Association Information on the request and response primitive respectively. The meaning of this parameter is Application Context specific. For more information on the use of the Application Association Information, see Annex D.

### 7.4.2 Association Release

The A-RELEASE Service is invoked by a DIMSE-service-user to request the orderly termination of an Association between peer DIMSE-service-users. This part of the Standard does not specify any use of the parameters of the A-RELEASE service.

Figure 7.4-1. DICOM Application Entity and Association

The A-ABORT Service is invoked by a DIMSE-service-user to request the abrupt termination of the Association between peer DIMSE-service-users. The A-ABORT invoking DIMSE-service-user shall include (within the A-ABORT user information field) the Abort Source parameter. The Abort Source parameter indicates the initiating source of the abort. It takes one of the following symbolic values:

- DIMSE-service-provider

- DIMSE-service-user

Reference PS3.8 for more information on the A-RELEASE and A-ABORT services.

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