Working with DICOM Associate Connections

Once a DICOM Network has been established, the Network connection must be associated. This is also referred to as establishing a DICOM Associate connection. The DICOM Associate connection serves to establish how the two AEs will communicate and the nature of the data that will be transferred. For example, the DICOM Associate connection can establish the following

The organization of the data — Little Endian vs Big Endian, Implicit VR vs Explicit VR.
Compression type.
The type of data that will be transferred — CT Image Storage Class, Printer Class, or Patient Study Query Find Class
The role of a connection member — SCU, SCP, or both.
Maximum size of the data "chunk" to be sent, if a maximum exists.
Whether asynchronous operations are allowed.
The presence of user-defined information.

An SCU requests the creation of an Associate connection with an SCP with which it has established a DICOM Network connection (not yet associated). The SCU sends the SCP an Associate Request message outlining the data it wishes to transfer, and the how the transfer can occur. The SCP can accept or reject the Associate connection request, based on whether the SCP supports the data and communication characteristics outlined by the SCU. If the connection is accepted, the DICOM Associate connection is established and the two AEs can begin transferring messages and data.

In this documentation a DICOM connection which has been associated will be referred to as a DICOM Associate connection or a DICOM Associate. Information concerning the nature of the DICOM Associate Network will be maintained in and accessed through a DICOM Associate handle.

LEADTOOLS provides a number of functions for creating a DICOM Associate connection, modifying a DICOM Associate handle and retrieving information about a DICOM Associate connection.

Creating a DICOM Associate connection consists of creating the DICOM Associate handle that outlines the characteristics of the transfer and sending messages to request, accept or reject a DICOM Associate connection.