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Implementing a Logging Plug-in

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Implementing a Logging Plug-in

To retrieve client log information from the server, you must implement the OnEvent method on the IWMSEventNotificationPlugin interface and retrieve the WMS_COMMAND_CONTEXT_BODY value from the command context. WMS_COMMAND_CONTEXT_BODY contains a pointer to a buffer that contains the log information in XML format as illustrated below. For more information about the format, see Log Data Format.

<xml>
   <Summary>....</Summary>
   <c-ip>...</c-ip>
   <Date>...</Date>
...
...
</xml>

The following example code illustrates how to retrieve the W3C information from the <Summary> tag.

C# Example

static readonly string strSummaryOpenTag = "<Summary>";
static readonly string strSummaryCloseTag = "</Summary>";

public virtual void OnEvent(
                            ref WMS_EVENT Event, 
                            IWMSContext UserCtx,
                            IWMSContext PresentationCtx,
                            IWMSCommandContext CommandCtx )
{
    try
    {
        IWMSContext CommandRequest;
        CommandCtx.GetCommandRequest(out CommandRequest);

        ContextNames cName = new ContextNames();
        object CacheProxyServer;
        CommandRequest.GetIUnknownValue(ContextNames.WMS_SERVER_CACHE_MANAGER,
                                ContextNames.WMS_SERVER_CACHE_MANAGER_ID,
                                out CacheProxyServer,
                                0);

        object ContextBody;
        CommandRequest.GetIUnknownValue("@WMS_COMMAND_CONTEXT_BODY",
                                        11,
                                        out ContextBody,
                                        0 );

        INSSBuffer NsBuffer = ContextBody as INSSBuffer;
        if( null == NsBuffer)
        {
            return;
        }

        string strContext = GetStringFromNSSBuffer( NsBuffer );

        // Find the beginning of the summary open tag.
        int iBegin = strContext.IndexOf( strSummaryOpenTag );
        if( -1 == iBegin )
        {
            return;
        }
        iBegin += strSummaryOpenTag.Length ;

        // Find the end of the summary tag.
        int iEnd = strContext.IndexOf( strSummaryCloseTag );
        if( -1 == iEnd )
        {
            return;
        }

        if( iEnd > iBegin )
        {
            string strSummary = strContext.Substring( iBegin, iEnd - iBegin );

            // The LogToDB function must be defined by you, 
            // depending on what you want to do with the log data.
            LogToDb( strSummary );
        }
    }
    catch
    {
        // TODO: Add exception handling code.
    }
}

string GetStringFromNSSBuffer( INSSBuffer NsBuffer )
{
    uint bufSize;
    IntPtr[] BufArr = { new IntPtr() };
    IntPtr pBuf = Marshal.UnsafeAddrOfPinnedArrayElement( BufArr, 0 );
    NsBuffer.GetBufferAndLength( pBuf, out bufSize );
    string s = Marshal.PtrToStringUni( BufArr[0], (int) bufSize / 2 );
    return s;
}

See Also

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