Creating a DICOM Network Connection

When establishing a connection between two AEs, for the purpose of transferring DICOM data and messages, the first step is to create a DICOM Network connection.

The AE acting as an SCP must have a DICOM Network handle and the AE acting as an SCU must have a DICOM Network handle. In addition, every time an SCP accepts a new connection request from an SCU, the SCP creates another DICOM Network handle for the newly connected SCU. This provides the SCP with memory for maintaining information about the SCU and that particular connection. Steps for establishing a DICOM Network connection are given below for both the SCU and the SCP.

Creating a network handle for an SCU

Create the DICOM Network handle by calling L_DicomCreateNet.
Initialize the DICOM Network handle by calling L_DicomStartUp. This must be done before any DICOM Network Operations functions are called. Please note that this only needs to be called once for each application.
Call L_DicomSetCallback to set the callback functions you wish to use.
To connect to an SCP, call L_DicomConnect or L_DicomConnectExt. This will generate a call to the ACCEPTCALLBACK function on the SCP to let the SCP know that a connection request has been received.
The SCP should respond by calling L_DicomAccept. This will generate a call to the CONNECTCALLBACK on the SCU. At this time the DICOM Network connection has been established.

Creating a network handle for an SCP

Create the DICOM Network handle by calling L_DicomCreateNet.
Initialize the DICOM Network handle by calling L_DicomStartUp. This must be done before any DICOM Network Operations functions are called. Please note that this only needs to be called once for each application.
Call L_DicomSetCallback to set the callback functions you wish to use.
To listen for incoming connection requests, call L_DicomListen or L_DicomListenExt.
When an SCU wishes to connect to an SCP, the SCU calls L_DicomConnect or L_DicomConnectExt. This generates a call to the ACCEPTCALLBACK function on the SCP to let the SCP know that a connection request has been received.
The SCP should respond by calling L_DicomCreateNet, L_DicomSetCallback and L_DicomAccept. Calling L_DicomCreateNet and L_DicomSetCallback creat a network handle for this specific connection and allows the SCP to maintain information about this connection. Calling L_DicomAccept will generate a call to the CONNECTCALLBACK on the SCU. At this time the DICOM Network connection has been established. (An SCP should always accept a connection request. Once the connection is made the SCP can check the SCU and close the connection if it does not wish to maintain it. Since the connection requests are queued, if the connection is not accepted, it remains in the queue. When the next request is received, it is placed in the queue behind the first request. Calling L_DicomAccept at this point will connect the first request, not the second, since the first request is still in the queue.)
Establish a security layer. For more information on security layers, refer to Adding Security to a DICOM Connection and Adding TLS Security to a DICOM Connection.

For more information on creating SCUs and SCPs, refer to Creating an SCU or Creating an SCP.

Once the DICOM Network Connection has been made, you must create a DICOM Associate Connection before DICOM messages and data can be transferred between the AEs. For more information in creating a DICOM Associate connection, refer to Creating a DICOM Associate Connection.