VB Forum / Win API / July 2008

I'm trying to use
http://msdn.microsoft.com/en-us/library/aa382711(VS.85).aspx function in
.NET.

p/invoke data type conversion:
http://msdn.microsoft.com/en-us/library/ac7ay120.aspx

BOOL WINAPI EcGetSubscriptionRunTimeStatus(  
 __in   LPCWSTR SubscriptionName,  
 __in   EC_SUBSCRIPTION_RUNTIME_STATUS_INFO_ID StatusInfoId,  
 __in   LPCWSTR EventSourceName,  
 __in   DWORD Flags,  
 __in   DWORD StatusValueBufferSize,  
 __in   PEC_VARIANT StatusValueBuffer,  
 __out  PDWORD StatusValueBufferUsed  
);  
 

This is my prototype in VB.NET

Private Declare Unicode Function EcGetSubscriptionRunTimeStatus Lib
"wecapi.dll" _  
(ByVal SubscriptionName As String, _  
ByVal StatusInfoId As EC_SUBSCRIPTION_RUNTIME_STATUS_INFO_ID, _  
ByVal EventSourceName As String, _  
ByVal Flags As UInt32, _  
ByVal StatusValueBufferSize As UInt32, _  
ByVal StatusValueBuffer As IntPtr, _
ByRef StatusValueBufferUsed As UInt32) _  
As Boolean  

I do not know how to get the data from the StatusValueBuffer.  What value do
I pass to it?  Is it even the right data-type?  Can someone shed some light
on this interop problem?  Would tlbimp.exe be helpful in this case?

Here is a usage example in C++:
http://msdn.microsoft.com/en-us/library/bb513655(VS.85).aspx

Thanks!

UPDATE...

I got it to work somewhat... (I wish I understood what is going on here!)  

The second call to EcGetSubRTS returns code other than 0... so I assume that
it fails.  However, changing the StatusValuebuffer to Byte() returns
(1000000020000000).  And I have confirmed that position 0 is the actual
status.  Here is the code used:

1 Imports System.Runtime.InteropServices  
2 Imports System.Reflection  
3  
4 Public Class Form2  
5  
6     Private Const ERROR_SUCCESS As UInt16 = 0  
7  
8  
9     Private Enum EC_SUBSCRIPTION_RUNTIME_STATUS_INFO_ID As UInt32  
10         EcSubscriptionRunTimeStatusActive = 0  
11         EcSubscriptionRunTimeStatusLastError = 1  
12         EcSubscriptionRunTimeStatusLastErrorMessage = 2  
13         EcSubscriptionRunTimeStatusLastErrorTime = 3  
14         EcSubscriptionRunTimeStatusNextRetryTime = 4  
15         EcSubscriptionRunTimeStatusEventSources = 5  
16         EcSubscriptionRunTimeStatusLastHeartbeatTime = 6  
17     End Enum  
18  
19     Private Enum EC_SUBSCRIPTION_RUNTIME_STATUS_ACTIVE_STATUS As UInt32  
20         EcRuntimeStatusActiveStatusDisabled = 1  
21         EcRuntimeStatusActiveStatusActive = 2  
22         EcRuntimeStatusActiveStatusInactive = 3  
23         EcRuntimeStatusActiveStatusTrying = 4  
24     End Enum  
25  
26     Private Declare Unicode Function EcOpenSubscription Lib "wecapi.dll"
(ByVal SubscriptionName As String, ByVal AccessMask As UInt32, ByVal Flags As
UInt32) As IntPtr  
27  
28     Private Declare Unicode Function EcGetSubscriptionRunTimeStatus Lib
"wecapi.dll" (ByVal SubscriptionName As String, ByVal StatusInfoId As
EC_SUBSCRIPTION_RUNTIME_STATUS_INFO_ID, ByVal EventSourceName As String,
ByVal Flags As UInt32, ByVal StatusValueBufferSize As UInt32, ByVal
StatusValueBuffer As Byte(), ByRef StatusValueBufferUsed As UInt32) As
Boolean  
29  
30     Private Declare Unicode Function EcClose Lib "wecapi.dll" (ByVal
SubHandle As IntPtr) As Boolean  
31  
32     Private Sub GetSubStatus(ByVal SubscriptionName As String)  
33         Dim ec_handle As IntPtr  
34         Dim dwRetVal As UInt32  
35         Dim vStatusBuffer As Byte() = Nothing  
36         Dim vStatusSize As UInt32  
37         Dim vStatusUsed As UInt32  
38         Dim er As Int16  
39  
40         Try  
41             ec_handle = EcOpenSubscription(SubscriptionName, 1, 2)  
42  
43             If ec_handle <> IntPtr.Zero Then  
44                 dwRetVal =
EcGetSubscriptionRunTimeStatus(SubscriptionName, _  
45                    
EC_SUBSCRIPTION_RUNTIME_STATUS_INFO_ID.EcSubscriptionRunTimeStatusActive, _  
46                     vbNullString, _  
47                     Nothing, _  
48                     vStatusSize, _  
49                     vStatusBuffer, _  
50                     vStatusUsed)  
51                 If dwRetVal = ERROR_SUCCESS And vStatusUsed > 0 Then  
52  
53                     Array.Resize(vStatusBuffer, vStatusUsed)  
54  
55                     dwRetVal =
EcGetSubscriptionRunTimeStatus(SubscriptionName, _  
56                    
EC_SUBSCRIPTION_RUNTIME_STATUS_INFO_ID.EcSubscriptionRunTimeStatusActive, _  
57                     vbNullString, _  
58                     Nothing, _  
59                     vStatusBuffer.Length, _  
60                     vStatusBuffer, _  
61                     vStatusUsed)  
62  
63                     If dwRetVal = ERROR_SUCCESS Then  
64                         MsgBox(vStatusBuffer.GetValue(0).tostring)  
65                     Else  
66                         MsgBox("err : runtimestatus2 : " &
dwRetVal.ToString)  
67                     End If  
68  
69                     ''--------------------------------------------------  
70                     'Dim tempBuffer As IntPtr =
Marshal.AllocHGlobal(CInt(vStatusUsed))  
71                     'Dim tempBufferInt As UInt32 = tempBuffer.ToInt32  
72  
73                     'dwRetVal =
EcGetSubscriptionRunTimeStatus(SubscriptionName, _  
74                     '
EC_SUBSCRIPTION_RUNTIME_STATUS_INFO_ID.EcSubscriptionRunTimeStatusActive, _  
75                     'vbNullString, _  
76                     'Nothing, _  
77                     'tempBufferInt, _  
78                     'vStatusBuffer, _  
79                     'vStatusUsed)  
80  
81                     'Dim buffer(tempBufferInt) As Byte  
82                     'Marshal.Copy(tempBufferInt, buffer, 0, vStatusUsed)  
83                     ''------------------------------------------------  
84  
85  
86  
87                     'MsgBox(Marshal.ReadInt16(vStatusBuffer))  
88                     ' MsgBox(Marshal.PtrToStringAuto(vStatusBuffer, 16))  
89                     MsgBox(dwRetVal.ToString & " : buffSize" &
vStatusSize.ToString & _  
90                            " : buffUsed" & vStatusUsed.ToString & _  
91                            " : Buff" & vStatusBuffer.ToString)  
92                 Else  
93                     MsgBox("err : runtimestatus : " & dwRetVal.ToString)  
94                 End If  
95  
96  
97             Else  
98                 er = Marshal.GetLastWin32Error  
99                 MsgBox("win32 er: ec_handle = 0 : " & er.ToString)  
100             End If  
101  
102  
103         Catch ex As Exception  
104             MsgBox(ex.Message)  
105         Finally  
106             If ec_handle <> IntPtr.Zero Then  
107                 EcClose(ec_handle)  
108             End If  
109         End Try  
110     End Sub  
111  
112     Private Sub btnGetStat_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles btnGetStat.Click  
113         Try  
114             GetSubStatus(txtSubName.Text.Trim)  
115  
116         Catch ex As Exception  
117             MsgBox(ex.Message)  
118         End Try  
119     End Sub  
120  
121     Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load  
122  
123     End Sub  
124 End Class