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 object and the AE acting as an SCU must have a DICOM Network object. In addition, every time an SCP accepts a new connection request from an SCU, the SCP creates another DICOM Network object 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.

Establishing a DICOM Network Connection (SCU)

• Initialize the DICOM DLL by calling DicomNet.Startup. This must be done before any DICOM Network Operations methods are called. Please note that this only needs to be called once for each application.
• Create the DICOM Network object by instantiating the DicomNet class.
• To connect to an SCP, call DicomNet.Connect. This will generate a call to the DicomNet.OnAccept method on the SCP to let the SCP know that a connection request has been received.
• The SCP should respond by calling DicomNet.Accept. This will generate a call to the DicomNet.OnConnect method on the SCU. At this time the DICOM Network connection has been established.
• 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.

Establishing a DICOM Network Connection (SCP)

• Initialize the DICOM DLL by calling DicomNet.Startup. This must be done before any DICOM Network Operations methods are called. Please note that this only needs to be called once for each application.
• Create the DICOM Network object by instantiating the DicomNet class.
• To listen for incoming connection requests, call DicomNet.Listen.
• When an SCU wishes to connect to an SCP, the SCU calls DicomNet.Connect. This generates a call to the DicomNet.OnAccept method on the SCP to let the SCP know that a connection request has been received.
• The SCP should respond by creating a DICOM Network object and specifying this new object in a call to the DicomNet.Accept method. Creating an object for this specific connection allows the SCP to maintain information about the connection. Calling DicomNet.Accept will generate a call to DicomNet.OnConnect 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 DicomNet.Accept 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 and 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 on creating a DICOM Associate connection, refer to Creating a DICOM Associate Connection.