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SendNGetRequest Method

Summary
Sends an N-GET-REQ message to a peer member of a connection.
Syntax
C#
C++
public void SendNGetRequest( 
   byte presentationID, 
   int messageID, 
   string affectedClass, 
   string instance, 
   long[] attributes, 
   int count 
) 
public: 
void SendNGetRequest(  
   byte presentationID, 
   int messageID, 
   String^ affectedClass, 
   String^ instance, 
   array<int64>^ attributes, 
   int count 
)  

Parameters

presentationID
The Presentation Context ID. The ID provides information about both the class type of the data and the Transfer Syntax to use when transferring the data.

messageID
The Message ID. Each message sent by a member of a connection should have a unique ID. Since a member of a connection may send several messages, this ID allows that member to identify when a specific request has been completed.

affectedClass
The class affected by the request. This will be a SOP Class or a Meta SOP Class.

instance
The instance of the class. A server may, for example, have three instances of the Nuclear Medicine Class. This value identifies the data with a specific instance.

attributes
An array of the attributes to get. The attributes must be specified using the Data Element Tags. For a list of available Data Element Tags, refer to Data Element Tag Values.

count
The number of attributes being requested.

Remarks

Calling this method generates a call to OnReceiveNGetRequest on the SCP. The SCP should respond by calling SendNGetResponse which will generate a call to OnReceiveNGetResponse.

Example

This is a comprehensive sample that shows how to process a DICOM N-Get operation on both the SCP (server) and the SCU (client) sides.

C#
using Leadtools; 
using Leadtools.Dicom; 
 
 
[StructLayout(LayoutKind.Sequential)] 
public struct MSG 
{ 
   public IntPtr hwnd; 
   public uint message; 
   public IntPtr wParam; 
   public IntPtr lParam; 
   public uint time; 
   public System.Drawing.Point p; 
} 
 
public enum WaitReturn 
{ 
   Complete, 
   Timeout, 
} 
 
class Utils 
{ 
   [DllImport("user32.dll")] 
   [return: MarshalAs(UnmanagedType.Bool)] 
   static extern bool PeekMessage(out MSG lpMsg, IntPtr hWnd, 
                                  uint wMsgFilterMin, uint wMsgFilterMax, 
                                  uint wRemoveMsg); 
 
   [DllImport("user32.dll")] 
   static extern bool TranslateMessage([In] ref MSG lpMsg); 
   [DllImport("user32.dll")] 
   static extern IntPtr DispatchMessage([In] ref MSG lpmsg); 
 
   const uint PM_REMOVE = 1; 
 
   public static WaitReturn WaitForComplete(double mill, WaitHandle wh) 
   { 
      TimeSpan goal = new TimeSpan(DateTime.Now.AddMilliseconds(mill).Ticks); 
 
      do 
      { 
         MSG msg = new MSG(); 
 
         if (PeekMessage(out msg, IntPtr.Zero, 0, 0, PM_REMOVE)) 
         { 
            TranslateMessage(ref msg); 
            DispatchMessage(ref msg); 
         } 
 
         if (wh.WaitOne(new TimeSpan(0, 0, 0), false)) 
         { 
            return WaitReturn.Complete; 
         } 
 
         if (goal.CompareTo(new TimeSpan(DateTime.Now.Ticks)) < 0) 
         { 
            return WaitReturn.Timeout; 
         } 
 
      } while (true); 
   } 
} 
 
class Client : DicomNet 
{ 
   DicomExceptionCode _LastError = DicomExceptionCode.Success; 
   AutoResetEvent waitEvent = new AutoResetEvent(false); 
 
   public Client() 
       : base(null, DicomNetSecurityMode.None) 
   { 
   } 
 
   public DicomExceptionCode LastError 
   { 
      get 
      { 
         return _LastError; 
      } 
   } 
 
   public bool Wait() 
   { 
      WaitReturn ret; 
 
      _LastError = DicomExceptionCode.Success; 
      ret = Utils.WaitForComplete((5 * 60) * 1000, waitEvent); 
 
      return (ret == WaitReturn.Complete); 
   } 
 
   protected override void OnConnect(DicomExceptionCode error) 
   { 
      _LastError = error; 
      waitEvent.Set(); 
   } 
 
   protected override void OnReceiveAssociateAccept(DicomAssociate association) 
   { 
      waitEvent.Set(); 
   } 
 
   protected override void OnReceiveNGetResponse(byte presentationID, int messageID, string affectedClass, string instance, DicomCommandStatusType status, DicomDataSet dataSet) 
   { 
      DicomElement element; 
 
      StackTrace st = new StackTrace(); 
 
      Debug.WriteLine(st.GetFrame(0).GetMethod().DeclaringType.Name + 
                      ":" + st.GetFrame(0).GetMethod().Name); 
 
      Debug.Assert(messageID == 1, "Invalid message id.  Should be 1"); 
      Debug.Assert(affectedClass == DicomUidType.SCImageStorage, "Affected class should be PatientRootQueryMove: " + DicomUidType.PatientRootQueryMove); 
      Debug.Assert(status == DicomCommandStatusType.Success, "Status should be success"); 
      Debug.Assert(dataSet != null, "Dataset should not be null"); 
 
      // 
      // Check Dataset 
      // 
      element = dataSet.FindFirstElement(null, DicomTag.PatientName, true); 
      Debug.Assert(element != null, "Element (PatientName) should not be null"); 
      Debug.Assert(dataSet.GetStringValue(element, 0) == "TEST", "PatientName should be TEST"); 
 
      element = dataSet.FindFirstElement(null, DicomTag.PatientID, true); 
      Debug.Assert(element != null, "Element (PatientID) should not be null"); 
      Debug.Assert(dataSet.GetStringValue(element, 0) == "ID", "PatientID should be ID"); 
 
      element = dataSet.FindFirstElement(null, DicomTag.PatientSex, true); 
      Debug.Assert(element != null, "Element (PatientSex) should not be null"); 
      Debug.Assert(dataSet.GetStringValue(element, 0) == "M", "PatientSex should be M"); 
 
      element = dataSet.FindFirstElement(null, DicomTag.NumberOfPatientRelatedInstances, true); 
      Debug.Assert(element != null, "Element (NumberOfPatientRelatedInstances) should not be null"); 
      Debug.Assert(dataSet.GetConvertValue(element) == "1", "NumberOfPatientRelatedInstances should be 1"); 
 
      waitEvent.Set(); 
   } 
} 
 
class ServerConnection : DicomNet 
{ 
   public ServerConnection() 
       : base(null, DicomNetSecurityMode.None) 
   { 
   } 
 
   protected override void OnReceiveAssociateRequest(DicomAssociate association) 
   { 
      DicomAssociate retAssociation = new DicomAssociate(false); 
 
      Debug.Assert(association.Called == "ServerTest", "Called AETitle should be ServerTest"); 
      Debug.Assert(association.Calling == "ClientTest", "Calling AETitle should be ClientTest"); 
      Debug.Assert(association.ImplementClass == "1.2.840.114257.1", "Implementation class should be 1.2.840.114257.1"); 
      Debug.Assert(association.ImplementationVersionName == "1", "Implementation version should be 1"); 
      Debug.Assert(association.MaxLength == 0x100000, "Max length should be 0x100000"); 
      Debug.Assert(association.GetAbstract(1) == DicomUidType.VerificationClass, "Presentation index 1 should be " + DicomUidType.VerificationClass); 
      Debug.Assert(association.GetTransfer(1, 0) == DicomUidType.ImplicitVRLittleEndian, "Abstract Syntax (1,0) should be " + DicomUidType.ImplicitVRLittleEndian); 
 
      // 
      // Build our Association Accept 
      // 
      retAssociation.Called = association.Called; 
      retAssociation.Calling = association.Calling; 
      retAssociation.ImplementClass = association.ImplementClass; 
      retAssociation.ImplementationVersionName = association.ImplementationVersionName; 
      for (int x = 0; x < association.PresentationContextCount; x++) 
      { 
         byte id = association.GetPresentationContextID(x); 
         string abSyntax = association.GetAbstract(id); 
         string trSyntax = DicomUidType.ImplicitVRLittleEndian; 
 
         retAssociation.AddPresentationContext(id, 0, abSyntax); 
         if (association.GetTransferCount(id) > 0) 
         { 
            trSyntax = association.GetTransfer(id, 0); 
         } 
 
         retAssociation.AddTransfer(id, trSyntax); 
      } 
      SendAssociateAccept(retAssociation); 
   } 
 
   protected override void OnReceiveNGetRequest(byte presentationID, int messageID, string affectedClass, string instance, long[] attributes) 
   { 
      DicomDataSet ds = new DicomDataSet(); 
      DicomElement element; 
 
      StackTrace st = new StackTrace(); 
 
      Debug.WriteLine(st.GetFrame(0).GetMethod().DeclaringType.Name + 
                      ":" + st.GetFrame(0).GetMethod().Name); 
 
      byte id = Association.FindAbstract(affectedClass); 
 
      Debug.Assert(id == presentationID, "PresentationID is invalid"); 
      Debug.Assert(messageID == 1, "Invalid message id.  Should be 1"); 
      Debug.Assert(instance == "1.1.1.1.9999.2", "Instance should be 1.1.1.1.9999.2"); 
      Debug.Assert(attributes.Length == 4, "There should be 4 attributes"); 
 
      Debug.Assert(attributes[0] == DicomTag.PatientName, "Attribute 0 should be PatientName"); 
      Debug.Assert(attributes[1] == DicomTag.PatientID, "Attribute 1 should be PatientID"); 
      Debug.Assert(attributes[2] == DicomTag.PatientSex, "Attribute 2 should be PatientSex"); 
      Debug.Assert(attributes[3] == DicomTag.NumberOfPatientRelatedInstances, "Attribute 3 should be NumberOfPatientRelatedInstances"); 
 
      ds.Initialize(DicomClassType.Undefined, DicomDataSetInitializeType.ImplicitVRLittleEndian); 
 
      element = ds.FindFirstElement(null, DicomTag.PatientName, true); 
      if (element == null) 
      { 
         element = ds.InsertElement(null, false, DicomTag.PatientName, DicomVRType.UN, false, 0); 
      } 
      ds.SetStringValue(element, "TEST", DicomCharacterSetType.Default); 
 
      element = ds.FindFirstElement(null, DicomTag.PatientID, true); 
      if (element == null) 
      { 
         element = ds.InsertElement(null, false, DicomTag.PatientID, DicomVRType.UN, false, 0); 
      } 
      ds.SetStringValue(element, "ID", DicomCharacterSetType.Default); 
 
      element = ds.FindFirstElement(null, DicomTag.PatientSex, true); 
      if (element == null) 
      { 
         element = ds.InsertElement(null, false, DicomTag.PatientSex, DicomVRType.UN, false, 0); 
      } 
      ds.SetStringValue(element, "M", DicomCharacterSetType.Default); 
 
      element = ds.FindFirstElement(null, DicomTag.NumberOfPatientRelatedInstances, true); 
      if (element == null) 
      { 
         element = ds.InsertElement(null, false, DicomTag.NumberOfPatientRelatedInstances, DicomVRType.UN, false, 0); 
      } 
      ds.SetConvertValue(element, "1", 1); 
 
      SendNGetResponse(presentationID, messageID, affectedClass, instance, DicomCommandStatusType.Success, ds); 
   } 
} 
 
class Server : DicomNet 
{ 
   ServerConnection client; 
 
   public Server() 
       : base(null, DicomNetSecurityMode.None) 
   { 
   } 
 
   protected override void OnAccept(DicomExceptionCode error) 
   { 
      client = new ServerConnection(); 
 
      Accept(client); 
   } 
} 
 
public void SendNGetRequestSample() 
{ 
   DicomEngine.Startup(); 
   DicomNet.Startup(); 
 
   using (Server server = new Server()) 
   { 
      using (Client client = new Client()) 
      { 
         // 
         // Connect to server 
         // 
         server.Listen("127.0.0.1", 104, 1); // start server 
         client.Connect(null, 1000, "127.0.0.1", 104); // connect to server 
         if (!client.Wait()) // wait for connection to finish 
         { 
            Debug.Fail("Connection timed out"); 
         } 
         Debug.Assert(client.LastError == DicomExceptionCode.Success, "Connection failed"); 
         Debug.Assert(client.IsConnected(), "Client not connected"); 
 
         // 
         // Send associate request 
         // 
         DicomAssociate associate = new DicomAssociate(true); 
         long[] attributes = new long[4]; 
 
         associate.Called = "ServerTest"; 
         associate.Calling = "ClientTest"; 
         associate.ImplementClass = "1.2.840.114257.1"; 
         associate.ImplementationVersionName = "1"; 
         associate.MaxLength = 0x100000; 
         associate.AddPresentationContext(1, 0, DicomUidType.VerificationClass); 
         associate.AddTransfer(1, DicomUidType.ImplicitVRLittleEndian); 
         associate.AddPresentationContext(3, 0, DicomUidType.SCImageStorage); 
         associate.AddTransfer(3, DicomUidType.ImplicitVRLittleEndian); 
         client.SendAssociateRequest(associate); 
         if (!client.Wait()) // wait for connection to finish 
         { 
            Debug.Fail("SendAssociateRequest timed out"); 
         } 
 
         byte pid = client.Association.FindAbstract(DicomUidType.SCImageStorage); 
 
         // Set NGet attributes 
         attributes[0] = DicomTag.PatientName; 
         attributes[1] = DicomTag.PatientID; 
         attributes[2] = DicomTag.PatientSex; 
         attributes[3] = DicomTag.NumberOfPatientRelatedInstances; 
 
         client.SendNGetRequest(pid, 1, DicomUidType.SCImageStorage, "1.1.1.1.9999.2", attributes, attributes.Length); 
         if (!client.Wait()) // wait for NGet to finish 
         { 
            Debug.Fail("SendNGetRequest timed out"); 
         } 
         client.CloseForced(true); 
      } 
      server.CloseForced(true); 
   } 
 
   DicomEngine.Shutdown(); 
   DicomNet.Shutdown(); 
} 
Requirements

Target Platforms

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