.net – Programmatically logging to the Sharepoint ULS

netsharepointsharepoint-2007

I'd like to log stuff in my Sharepoint Web Parts, but I want it to go into the ULS. Most examples that I've found log into the Event Log or some other file, but I did not really find one yet for logging into the ULS.

Annoyingly, Microsoft.SharePoint.Diagnostics Classes are all marked Internal. I did find one example of how to use them anyway through reflection, but that looks really risky and unstable, because Microsoft may change that class with any hotfix they want.

The Sharepoint Documentation wasn't really helpful either – lots of Administrator info about what ULS is and how to configure it, but i have yet to find an example of supported code to actually log my own events.

Any hints or tips?

Edit: As you may see from the age of this question, this is for SharePoint 2007. In SharePoint 2010, you can use SPDiagnosticsService.Local and then WriteTrace. See the answer from Jürgen below.

Best Answer

Yes this is possible, see this MSDN article: http://msdn2.microsoft.com/hi-in/library/aa979595(en-us).aspx

And here is some sample code in C#:

using System;
using System.Runtime.InteropServices;
using Microsoft.SharePoint.Administration;

namespace ManagedTraceProvider
{
class Program
{
    static void Main(string[] args)
    {
        TraceProvider.RegisterTraceProvider();

        TraceProvider.WriteTrace(0, TraceProvider.TraceSeverity.High, Guid.Empty, "MyExeName", "Product Name", "Category Name", "Sample Message");
        TraceProvider.WriteTrace(TraceProvider.TagFromString("abcd"), TraceProvider.TraceSeverity.Monitorable, Guid.NewGuid(), "MyExeName", "Product Name", "Category Name", "Sample Message");

        TraceProvider.UnregisterTraceProvider();
    }
}

static class TraceProvider
{
    static UInt64 hTraceLog;
    static UInt64 hTraceReg;

    static class NativeMethods
    {
        internal const int TRACE_VERSION_CURRENT = 1;
        internal const int ERROR_SUCCESS = 0;
        internal const int ERROR_INVALID_PARAMETER = 87;
        internal const int WNODE_FLAG_TRACED_GUID = 0x00020000;

        internal enum TraceFlags
        {
            TRACE_FLAG_START = 1,
            TRACE_FLAG_END = 2,
            TRACE_FLAG_MIDDLE = 3,
            TRACE_FLAG_ID_AS_ASCII = 4
        }

        // Copied from Win32 APIs
        [StructLayout(LayoutKind.Sequential)]
        internal struct EVENT_TRACE_HEADER_CLASS
        {
            internal byte Type;
            internal byte Level;
            internal ushort Version;
        }

        // Copied from Win32 APIs
        [StructLayout(LayoutKind.Sequential)]
        internal struct EVENT_TRACE_HEADER
        {
            internal ushort Size;
            internal ushort FieldTypeFlags;
            internal EVENT_TRACE_HEADER_CLASS Class;
            internal uint ThreadId;
            internal uint ProcessId;
            internal Int64 TimeStamp;
            internal Guid Guid;
            internal uint ClientContext;
            internal uint Flags;
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        internal struct ULSTraceHeader
        {
            internal ushort Size;
            internal uint dwVersion;
            internal uint Id;
            internal Guid correlationID;
            internal TraceFlags dwFlags;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
            internal string wzExeName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
            internal string wzProduct;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
            internal string wzCategory;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 800)]
            internal string wzMessage;
        }

        [StructLayout(LayoutKind.Sequential)]
        internal struct ULSTrace
        {
            internal EVENT_TRACE_HEADER Header;
            internal ULSTraceHeader ULSHeader;
        }

        // Copied from Win32 APIs
        internal enum WMIDPREQUESTCODE
        {
            WMI_GET_ALL_DATA = 0,
            WMI_GET_SINGLE_INSTANCE = 1,
            WMI_SET_SINGLE_INSTANCE = 2,
            WMI_SET_SINGLE_ITEM = 3,
            WMI_ENABLE_EVENTS = 4,
            WMI_DISABLE_EVENTS = 5,
            WMI_ENABLE_COLLECTION = 6,
            WMI_DISABLE_COLLECTION = 7,
            WMI_REGINFO = 8,
            WMI_EXECUTE_METHOD = 9
        }

        // Copied from Win32 APIs
        internal unsafe delegate uint EtwProc(NativeMethods.WMIDPREQUESTCODE requestCode, IntPtr requestContext, uint* bufferSize, IntPtr buffer);

        // Copied from Win32 APIs
        [DllImport("advapi32.dll", CharSet = CharSet.Unicode)]
        internal static extern unsafe uint RegisterTraceGuids([In] EtwProc cbFunc, [In] void* context, [In] ref Guid controlGuid, [In] uint guidCount, IntPtr guidReg, [In] string mofImagePath, [In] string mofResourceName, out ulong regHandle);

        // Copied from Win32 APIs
        [DllImport("advapi32.dll", CharSet = CharSet.Unicode)]
        internal static extern uint UnregisterTraceGuids([In]ulong regHandle);

        // Copied from Win32 APIs
        [DllImport("advapi32.dll", CharSet = CharSet.Unicode)]
        internal static extern UInt64 GetTraceLoggerHandle([In]IntPtr Buffer);

        // Copied from Win32 APIs
        [DllImport("advapi32.dll", SetLastError = true)]
        internal static extern uint TraceEvent([In]UInt64 traceHandle, [In]ref ULSTrace evnt);
    }

    public enum TraceSeverity
    {
        Unassigned = 0,
        CriticalEvent = 1,
        WarningEvent = 2,
        InformationEvent = 3,
        Exception = 4,
        Assert = 7,
        Unexpected = 10,
        Monitorable = 15,
        High = 20,
        Medium = 50,
        Verbose = 100,
    }

    public static void WriteTrace(uint tag, TraceSeverity level, Guid correlationGuid, string exeName, string productName, string categoryName, string message)
    {
        const ushort sizeOfWCHAR = 2;
        NativeMethods.ULSTrace ulsTrace = new NativeMethods.ULSTrace();

        // Pretty standard code needed to make things work
        ulsTrace.Header.Size = (ushort)Marshal.SizeOf(typeof(NativeMethods.ULSTrace));
        ulsTrace.Header.Flags = NativeMethods.WNODE_FLAG_TRACED_GUID;
        ulsTrace.ULSHeader.dwVersion = NativeMethods.TRACE_VERSION_CURRENT;
        ulsTrace.ULSHeader.dwFlags = NativeMethods.TraceFlags.TRACE_FLAG_ID_AS_ASCII;
        ulsTrace.ULSHeader.Size = (ushort)Marshal.SizeOf(typeof(NativeMethods.ULSTraceHeader));

        // Variables communicated to SPTrace
        ulsTrace.ULSHeader.Id = tag;
        ulsTrace.Header.Class.Level = (byte)level;
        ulsTrace.ULSHeader.wzExeName = exeName;
        ulsTrace.ULSHeader.wzProduct = productName;
        ulsTrace.ULSHeader.wzCategory = categoryName;
        ulsTrace.ULSHeader.wzMessage = message;
        ulsTrace.ULSHeader.correlationID = correlationGuid;

        // Pptionally, to improve performance by reducing the amount of data copied around,
        // the Size parameters can be reduced by the amount of unused buffer in the Message
        if (message.Length < 800)
        {
            ushort unusedBuffer = (ushort) ((800 - (message.Length + 1)) * sizeOfWCHAR);
            ulsTrace.Header.Size -= unusedBuffer;
            ulsTrace.ULSHeader.Size -= unusedBuffer;
        }

        if (hTraceLog != 0)
            NativeMethods.TraceEvent(hTraceLog, ref ulsTrace);
    }

    public static unsafe void RegisterTraceProvider()
    {
        SPFarm farm = SPFarm.Local;
        Guid traceGuid = farm.TraceSessionGuid;
        uint result = NativeMethods.RegisterTraceGuids(ControlCallback, null, ref traceGuid, 0, IntPtr.Zero, null, null, out hTraceReg);
        System.Diagnostics.Debug.Assert(result == NativeMethods.ERROR_SUCCESS);
    }

    public static void UnregisterTraceProvider()
    {
        uint result = NativeMethods.UnregisterTraceGuids(hTraceReg);
        System.Diagnostics.Debug.Assert(result == NativeMethods.ERROR_SUCCESS);
    }

    public static uint TagFromString(string wzTag)
    {
        System.Diagnostics.Debug.Assert(wzTag.Length == 4);
        return (uint) (wzTag[0] << 24 | wzTag[1] << 16 | wzTag[2] << 8 | wzTag[3]);
    }

    static unsafe uint ControlCallback(NativeMethods.WMIDPREQUESTCODE RequestCode, IntPtr Context, uint* InOutBufferSize, IntPtr Buffer)
    {
        uint Status;
        switch (RequestCode)
        {
            case NativeMethods.WMIDPREQUESTCODE.WMI_ENABLE_EVENTS:
                hTraceLog = NativeMethods.GetTraceLoggerHandle(Buffer);
                Status = NativeMethods.ERROR_SUCCESS;
                break;
            case NativeMethods.WMIDPREQUESTCODE.WMI_DISABLE_EVENTS:
                hTraceLog = 0;
                Status = NativeMethods.ERROR_SUCCESS;
                break;
            default:
                Status = NativeMethods.ERROR_INVALID_PARAMETER;
                break;
        }

        *InOutBufferSize = 0;
        return Status;
    }
}

}

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