eprogrammer

SiteMaps made easy

eprogrammer — Sun, 31 Jan 2010 17:12:18 GMT

If you’re a site admin or asp.net developer for an internet site, you certainly need to look into sitemaps, if you want to perform SEO.

It’s not necessary to simply crawl your own site and then to give every page a priority, but consider this for a forum or other pages which are irregularly or often updated. If you don’t want to have crawlers do unneeded roundtrips, implement a sitemap.

‘robots.txt’ should contain a reference to your map eg. Sitemap: http://www.myfantasticsite.com/sitemap.xml

Ideas of this class, written using C#, can be found anywhere on the net. However, as some might know me, I like it to be finished and neat and a self-supporting class ready for usage (e.g. it must not be written to a string to add or remove wished attributes that the serializer could not handle).

The following things are solved.
Since ‘changefreq’ and ‘lastmod’ and ‘priority’ are optional values, you don’t want the XmlSerializer to create empty tags!
This is done by adding a DefaultValue attribute. It will cause XmlSerializer to check the current value against the default value. If they are equal, it is considered to be an empty non existing tag. Remember, that the defaultvalues need to be out of the range of possible values! Therefore, EnumChangeFreq contains an extra member ‘notused’
Remember, the Xml.Serialization name space, offers the tools to get it done without converting your loading your XML in to some XmlDocument class.

You can use the class as follows.
UrlSet retVal = new UrlSet();

retVal.AddUrl(new Url() { LastModifiedDateTime = DateTime.Now.ToUniversalTime(), Loc = “http://www.myfantasticsite.com/blah.aspx”) });

Retrieve the XML sitemap string.
string xml = null;
using (var io = (MemoryStream)retVal.ToStream())
{
xml = new UTF8Encoding().GetString(io.ToArray());
}

or, to write it directly to an output stream

using (var io = (MemoryStream)retVal.ToStream())
{

//todo: Deal with Response.Cache, etag and last modified to avoid unnecessary round trips.
Response.ContentType = “text/xml”;
Response.CharSet = “utf-8”;
Response.BinaryWrite(retVal.ToArray());

}

using System;
using System.Xml;
using System.Xml.Serialization;
using System.ComponentModel;
using System.IO;

namespace adccure
{

    public enum EnumChangeFreq
    {
        notset,
        always,
        hourly,
        daily,
        weekly,
        monthly,
        yearly,
        never
    }

[

[XmlRoot(ElementName = "urlset", Namespace = SCHEMA_SITEMAP)]
public sealed class UrlSet
{
    [XmlNamespaceDeclarations]
    public XmlSerializerNamespaces xmlns;
    private const string XSI_NAMESPACE = "http://www.w3.org/2001/XMLSchema-instance";
    private const string SCHEMA_SITEMAP = "http://www.sitemaps.org/schemas/sitemap/0.9";

private Url[] _url;

    public UrlSet()
    {
        _url = new Url[0];
        xmlns = new XmlSerializerNamespaces();
        xmlns.Add("xsi", XSI_NAMESPACE);
        SchemaLocation = SCHEMA_SITEMAP + " " + "http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd";

    }
    [XmlAttribute(AttributeName = "schemaLocation", Namespace = XSI_NAMESPACE)]
    public string SchemaLocation;

    public void AddUrl(Url url)
    {
        int l = _url.Length + 1;
        Array.Resize(ref _url, l);
        _url[l - 1] = url;
    }

    [XmlElement(ElementName = "url")]
    public Url[] url
    {
        get { return _url; }
        set { _url = value; } //bogus
    }
    /// <summary>
    /// serializes the UrlSet to a sitemap.xsd conform string ready for saving to disk.
    /// </summary>
    /// <returns>a Stream object</returns>
    public Stream ToStream()
    {
        XmlSerializer xmlser = new XmlSerializer(GetType());
        var io = new MemoryStream();
        xmlser.Serialize(new StreamWriter(io, Encoding.UTF8), this);
        io.Position = 0;
        return io;
    }
}

    public sealed class Url
    {
        private string _loc;
        private DateTime _lastmod;
        private float _priority;
        private EnumChangeFreq _changefreq;

        public Url()
        {
            //setting defaults
            _changefreq = EnumChangeFreq.notset;
            _priority = 0.0F;
            _lastmod = DateTime.MinValue;
        }

        [XmlElement(ElementName = "loc")]
        public string Loc
        {
            get
            {
                return _loc;
            }

            set
            {
                if (string.IsNullOrEmpty(value))
                {
                    throw new ArgumentNullException();
                }
                if (value.Length < 12 || value.Length > 2048)
                {
                    throw new ArgumentException("loc must be between 12 and 2048 in length");
                }
                _loc = value;
            }
        }
        [XmlElement(ElementName = "lastmod"), DefaultValue(typeof(DateTime), "1-1-0001")]
        public DateTime LastModifiedDateTime
        {
            get
            {
                return _lastmod;
            }

            set
            {
                _lastmod = new DateTime(value.Year, value.Month, value.Day, value.Hour, value.Minute, value.Second, value.Kind);

            }
        }
        [XmlElement(ElementName = "changefreq")]
        [DefaultValue(EnumChangeFreq.notset)]
        public EnumChangeFreq ChangeFreq
        {
            get
            {
                return _changefreq;
            }

            set
            {
                _changefreq = value;
            }
        }
        [XmlElement(ElementName = "priority")]
        [DefaultValue(0.0F)]
        public float Priority
        {
            get
            {
                return _priority;
            }

            set
            {
                if (value < 0 || value > 1.0)
                {
                    throw new ArgumentException("Must be between 0 and 1");
                }
                _priority = value;
            }
        }
    }
}

Tags van Technorati: C#,sitemaps,XmlSerializer

Howto: Create a custom numeric pager for the ASP.NET Gridview Control

eprogrammer — Wed, 28 Oct 2009 20:51:00 GMT

Figure 1: Our custom pager in action!

I never have liked the concept of storing all the data in whatever form (DataTable/Lists of records/etc.) to the ASP.NET gridview control and having it automatically manage paging for me. This could however be improved using Visual Studio 2008 wizards. However, this requires writing stored procedures.

I’ve got a concept for you, which works without a lot of extra work. The concept is:

Inherit from asp:GridView and override the PageCount and the PageIndex properties
Create in instance of my CustomPager class at DataBinding time.

The result is as shown in figure 1: It adheres to PageButtonCount, to any styles that you have applied to the GridView and it features a ‘jump to’ page input box.
The ‘native’ event handling in your ASPX, still can be maintained by this code since it emulates the PageIndexChanging event.

Other solutions, implement an AJAX updatepanel per row. This really minimizes unnecessary refreshing of grid data.
However, I don’t mind if say, 30 rows are being pulled from a DB and bound to a GridView. If we do so, we also get the best of two worlds, in one world, we get all data and have a fresh update of the real table rows, and in the other world, we have just the active row being fetched and we could end up having outdated data on our screen because of (for instance) co-writers/typers who updated rows at the database which are not reflected at our screen in grid (which is displayed using a gridview).

So, in other words, I like this pager control since it is a balanced solution! It has been tested on 10,000 records. WHen I would page to for instance, page 900, it really is a matter of fractions of a second to get a response. (For paging solutions on SQL server data tables which contain say millions of rows, we would need a more sophisticated approach).

Here is the control source (it’s called gridhelper.cs)! (In theory, it should work for .NET 2.0 up to 3.5)

// if you use this code, please leave the original author
//author: Egbert Nierop
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace adccure.tools
{
    public sealed class GridView2 : GridView
    {
        public GridView2()
            : base()
        {
        }
        private int _pageCount;

        public override int PageIndex
        {
            get
            {
                object o = ViewState["pgi"];
                return o == null ? 0 : (int)o;
            }
            set
            {
                ViewState["pgi"] = value;
            }
        }

        public override int PageCount
        {
            get
            {
                return _pageCount;
            }

        }
        public void PageCountSet(int pageCount)
        {
            _pageCount = pageCount;
        }
    }

    public sealed class CustomPager : ITemplate
    {
        readonly Table tbl;
        readonly GridView2 _grid;

        //readonly int _totalPages;
        public CustomPager(GridView2 grid, int totalPages)
        {
            tbl = new Table();
            grid.PageCountSet(totalPages);
            tbl.Width = Unit.Percentage(100);
            _grid = grid;
        }
        void ITemplate.InstantiateIn(Control container)
        {
            container.Controls.Add(tbl);

            int pageSize = _grid.PageSize;
            int pageIndex = _grid.PageIndex;
            int pageButtonCount = _grid.PagerSettings.PageButtonCount;
            int pageCount = _grid.PageCount;
            ClientScriptManager cs = _grid.Page.ClientScript;
            _grid.PagerSettings.Visible = true;
            var trow = new TableRow();
            var trowpagePosition = new TableRow();
            tbl.Rows.Add(trow);
            tbl.Rows.Add(trowpagePosition);
            TextBox tb = new TextBox();
            tb.ID = "txtJumpPage";
            tb.MaxLength = 4;
            tb.Width = Unit.Pixel(40);
            tb.Text = (pageIndex + 1).ToString();
            //avoid bubble up by return false
            tb.Attributes["onkeydown"] = string.Format("if (event.keyCode==13) {__doPostBack('{0}', 'Page$' + this.value ); return false;}", _grid.UniqueID);

            LiteralControl lit = new LiteralControl(string.Format(" of {0}", (pageCount + 1).ToString()));
            TableCell posCaption = new TableCell();
            trowpagePosition.Cells.Add(posCaption);
            posCaption.Controls.Add(tb);
            posCaption.Controls.Add(lit);
            int cellspan = 0;
            if (pageIndex > 0)
            {
                var cellText = new TableCell();
                trow.Cells.Add(cellText);
                cellspan++;
                cellText.Controls.Add(new HyperLink()
                {
                    NavigateUrl = cs.GetPostBackClientHyperlink(_grid,
                    string.Format("Page${0}", pageIndex - pageButtonCount >= 0 ? (pageIndex - pageButtonCount) + 1 : 1), false),
                    Text = "<"
                });
            }
            for (int x = pageIndex; x < pageIndex + pageButtonCount && x <= pageCount; x++)
            {
                var cellText = new TableCell();
                cellspan++;
                trow.Cells.Add(cellText);
                cellText.Controls.Add(new HyperLink()
                {
                    NavigateUrl = cs.GetPostBackClientHyperlink(_grid,
                        string.Format("Page${0}", x + 1), false),
                    Text = (x + 1).ToString(),
                });

            }
            if (pageIndex + pageButtonCount < pageCount)
            {
                var cellText = new TableCell();
                cellspan++;
                trow.Cells.Add(cellText);

                cellText.Controls.Add(new HyperLink()
                {
                    NavigateUrl = cs.GetPostBackClientHyperlink(_grid,
                    string.Format("Page${0}", (pageIndex + pageButtonCount) + 1), false),
                    Text = ">"
                });
            }
            tbl.Visible = true;
            posCaption.HorizontalAlign = HorizontalAlign.Center;
            posCaption.ColumnSpan = cellspan;
        }
    }
}

Now, I don’t publish the code to read from sample data (such as northwind), it would be a yadda, yadda and you know the drill. (In my code, it is just a silly HttpReferrer table having all the columns which allow you research this specific statistical interest of your web site)
But in my datalayer, I have things like shown below. It is a great solution for those tables, for say, less than 100,000 records. SQL server is able to deal with these types of queries pretty well and we still avoid pumping around lots of redundant data on the network and gridview control.

public IList<HttpReferrer> getHttpReferrers(int pPage, int pPageSize, HttpReferrerSortOrder sortOrder,
                SortDirection sortDirection,
                out int totalRecords)
        {
            totalRecords = dcd.HttpReferrers.Count();
            IQueryable<HttpReferrer> retVal = null;
            if (sortDirection == SortDirection.Ascending)
            {
                switch (sortOrder)
                {
                    case HttpReferrerSortOrder.Referer:
                        retVal = dcd.HttpReferrers.OrderBy(t => t.Referrer);
                        break;
                    case HttpReferrerSortOrder.IP:
                        retVal = dcd.HttpReferrers.OrderBy(t => t.IP_Address);
                        break;
                    case HttpReferrerSortOrder.Page:
                        retVal = dcd.HttpReferrers.OrderBy(t => t.page);
                        break;
                    default:
                        retVal = dcd.HttpReferrers.OrderBy(t => t.ts);
                        break;
                }
            }
            else
            {
                switch (sortOrder)
                { case HttpReferrerSortOrder.Referer:
                        retVal = dcd.HttpReferrers.OrderByDescending(t => t.Referrer);
                        break;
                    case HttpReferrerSortOrder.IP:
                        retVal = dcd.HttpReferrers.OrderByDescending(t => t.IP_Address);
                        break;
                    case HttpReferrerSortOrder.Page:
                        retVal = dcd.HttpReferrers.OrderByDescending(t => t.page);
                        break;
                    default:
                        retVal = dcd.HttpReferrers.OrderByDescending(t => t.ts);
                        break;
                }
            }
            return retVal.Skip(pPage * pPageSize).Take(pPageSize).ToList();
        }

So, our Grid, can sort and it can page.

How do we deal with the paging event at the code behind the aspx?
It’s so simple!

void gridHttpReferrers_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
gridHttpReferrers.PageIndex = e.NewPageIndex;
gridHttpReferrers.DataBind();
}

void gridHttpReferrers_DataBinding(object sender, EventArgs e)

{   int totalRecords;
   int pageSize = gridHttpReferrers.PageSize;
   int pageIndex = gridHttpReferrers.PageIndex;
gridHttpReferrers.DataSource = datadal.getHttpReferrers(pageIndex, pageSize, SortOrder, SortDir, out totalRecords);
   gridHttpReferrers.PagerTemplate = new CustomPager(gridHttpReferrers, totalRecords);
   gridHttpReferrers.PageCountSet (totalRecords / pageSize);
}

What did I do to get the new grid behavior inside the ASPX?
Just rename the tag from asp:GridView to ctrl:GridView2 and create the reference (or in web.config)

<%@ Register TagPrefix="ctrl" Namespace="adccure.tools" %>

<ctrl:GridView2 runat="server" emptydatatext="No data available." ID="gridHttpReferrers" AllowPaging="true" AllowSorting="True" Width ="100%" AutoGenerateColumns="false" PageSize="20" DataKeyNames="ID"><PagerSettings Position="Top" PageButtonCount="20" />
<Columns> ETC.

So, I hope this code was quite enlightning for you and you can play with it and have fun.

Howto: Check the case sensitive existence of a file

eprogrammer — Mon, 06 Jul 2009 09:03:00 GMT

Sometimes, especially for files running on external FTP servers, where file names are case sensitive, a file named myFILE.html, is not the same file as myfile.html in the same path!

This function, can be used on an NTFS path for that purpose where File.Exists would fail, because it is case insensitive. (However, it does not enable you to have two files with just a different case in the same path)

/// <summary>
/// Checks existance of file using a case sensitive compare
/// </summary>
/// <param name="file">must be full filename</param>
/// <returns></returns>
static bool FileExists(string file)

{

string pathCheck = Path.GetDirectoryName(file);

string filePart = Path.GetFileName(file);

if (string.IsNullOrEmpty(pathCheck))

{

throw new ArgumentException("The file must include a full path", file);

}

string[] checkFiles = Directory.GetFiles(pathCheck, filePart, SearchOption.TopDirectoryOnly);

if (checkFiles != null && checkFiles.Length > 0)

{

//must be a binary compare

return Path.GetFileName(checkFiles[0]) == filePart;

}

return false;

}

Howto: Properly use the AccessCheck API for the current user

eprogrammer — Thu, 18 Jun 2009 21:50:00 GMT

I've seen people pulling the hair out for not getting this API workign for them.

The API, even if impersonating the current user, returns error 1309. "An attempt has been made to operate on an impersonation token by a thread that is not currently impersonating a client."

The clue is that this API, (and this is not clearly documented on the MSDN) needs a duplicated handle.

Anyway, spare your hair, have fun with the code. B.t.w. You can hire me for smart code and research on components etc..

http://www.adccure.nl for contact.

[StructLayout(LayoutKind.Sequential)]

internal struct GENERIC_MAPPING

{

internal uint GenericRead;

internal uint GenericWrite;

internal uint GenericExecute;

internal uint GenericAll;

}

[DllImport("advapi32.dll", SetLastError = false)]

static extern void MapGenericMask([In, MarshalAs(UnmanagedType.U4)] ref TokenAccessLevels AccessMask,

[In] ref GENERIC_MAPPING map);

[DllImport("advapi32.dll", SetLastError = true)]

[return: MarshalAs(UnmanagedType.Bool)]

public static extern bool DuplicateToken(IntPtr ExistingTokenHandle,

[MarshalAs(UnmanagedType.U4)] TokenImpersonationLevel level,

out int DuplicateTokenHandle);

[DllImport("advapi32.dll", SetLastError = true)]

[return: MarshalAs(UnmanagedType.Bool)] static extern bool AccessCheck(

[MarshalAs(UnmanagedType.LPArray)]

byte[] pSecurityDescriptor,

IntPtr ClientToken,

[MarshalAs(UnmanagedType.U4)]

TokenAccessLevels accessmask,

[In] ref GENERIC_MAPPING GenericMapping,

IntPtr PrivilegeSet,

ref int PrivilegeSetLength,

out uint GrantedAccess,

[MarshalAs(UnmanagedType.Bool)]

out bool AccessStatus);

[DllImport("kernel32")]

static extern void CloseHandle(IntPtr ptr);

internal static bool hasReadAccess(string path)

{

// Obtain the authenticated user's Identity

WindowsIdentity winId = WindowsIdentity.GetCurrent(TokenAccessLevels.Duplicate | TokenAccessLevels.Query);

WindowsImpersonationContext ctx = null;

int statError = 0;

IntPtr dupToken = IntPtr.Zero;

try

{

// Start impersonating

//ctx = winId.Impersonate(); works but AccessCheck does not like this

int outPtr;

//AccessCheck needs a duplicated token!

DuplicateToken(winId.Token, TokenImpersonationLevel.Impersonation, out outPtr);

dupToken = new IntPtr(outPtr);

ctx = WindowsIdentity.Impersonate(dupToken);

Folder.GENERIC_MAPPING map = new Folder.GENERIC_MAPPING();

map.GenericRead = 0x80000000;

map.GenericWrite = 0x40000000;

map.GenericExecute = 0x20000000;

map.GenericAll = 0x10000000;

TokenAccessLevels required = TokenAccessLevels.Query | TokenAccessLevels.Read | TokenAccessLevels.AssignPrimary | (TokenAccessLevels)0x00100000; // add synchronization

MapGenericMask(ref required, ref map);

uint status = 0;

bool accesStatus = false;

// dummy area the size should be 20 we don't do anything with it

int sizeps = 20;

IntPtr ps = Marshal.AllocCoTaskMem(sizeps);

//AccessControlSections.Owner | AccessControlSections.Group MUST be included,

//otherwise the descriptor would be seen with ERROR 1338

var ACE = Directory.GetAccessControl(path,

AccessControlSections.Access | AccessControlSections.Owner |

AccessControlSections.Group);

bool success = AccessCheck(ACE.GetSecurityDescriptorBinaryForm(), dupToken, required, ref map,

ps, ref sizeps, out status, out accesStatus);

Marshal.FreeCoTaskMem(ps);

if (!success)

{

statError = Marshal.GetLastWin32Error();

}

else

{

return accesStatus;

}

// Prevent exceptions from propagating

catch (Exception ex)

{

Trace.Write(ex.Message);

}

finally

{

// Revert impersonation

if (ctx != null)

ctx.Undo();

CloseHandle(dupToken);

}

if (statError != 0)

{

throw new Win32Exception(statError);

}

return false;

}

This code is just a cut and paste. You can make it pretty.

Fill a dropdownlist using the current UICulture in (ASP.NET)

eprogrammer — Thu, 18 Jun 2009 10:05:00 GMT

Just for educational purpose (as for myself as well :) ) I post this code.

Using this, a programmer can use a good practise, that is to use the culture information which is built in, into .NET instead of making that data him/herself.

based upon the following element in web.Config, the list will fill using the correct number of monthnames. It also keeps track of calendars, that have 13 months in some cultures.

using System;

using System.Collections.Generic;

using System.Web;

using System.Linq;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Threading;

using System.Globalization;

public partial class _Default : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

int monthNumber = 0;

CultureInfo ci = Thread.CurrentThread.CurrentUICulture;

var myMonthnames = ci.DateTimeFormat.MonthNames

.Take(ci.Calendar.GetMonthsInYear(DateTime.Today.Year)).Select(p => new { monthNo = ++monthNumber, monthName = p });

ddlMonthnames.DataTextField = "monthName";

ddlMonthnames.DataValueField = "monthNo";

ddlMonthnames.DataSource = myMonthnames;

ddlMonthnames.DataBind();

}

<option value="1">januari</option>

<option value="2">februari</option>

<option value="3">maart</option>

<option value="4">april</option>

<option value="8">augustus</option>

<option value="9">september</option>

<option value="10">oktober</option>

<option value="11">november</option>

<option value="12">december</option>

</select>

Performance and the future of LINQ expressions

eprogrammer — Wed, 17 Jun 2009 23:23:00 GMT

I was wondering if writing well known C# (or VB.NET if you wish) code flow statements, such as for .. and foreach etc. are faster or slower compared to a generic expression.

The results are refreshing . At least using this simple array iteration. Array Iterations on millions of elements, of course, are not the the real life CPU eaters for an average ASP.NET website (eg), but consider this code.

There are three loops, doing the same. (n.b.: I run a dual core i7200 CPU machine on Vista x64)

int ctr = 0;

var values = new string[1000000].

Select(p => p = (ctr++).

ToString()).

ToArray();

List<int> intList;

intList = values.Select(p => int.Parse(p)).ToList();

int[] test1, test2, test3;

// loop 10 times and calculate the average

test1 = new int[10];

test2 = new int[10];

test3 = new int[10];

for (int zz = 0; zz < 10; zz++)

{

// our millisecond counter

// it's ok to run this test several times to get an average score

int start = Environment.TickCount;

// convert the numeric array back to an int array

intList = values.Select(p => int.Parse(p)).ToList();

test1[zz] = Environment.TickCount - start;

//now do the same but using a foreach iteration

start = Environment.TickCount;

intList = new List<int>();

foreach (var p in values)

{

intList.Add(int.Parse(p));

}

test2[zz] = Environment.TickCount - start;

//do it a last time, but with a for{} iteration

// theoretically a this should save us an enumerator.

start = Environment.TickCount;

intList = new List<int>();

int z = values.Length;

for (int x = 0; x < z; x++)

{

intList.Add(int.Parse(values[x]));

}

test3[zz] = Environment.TickCount - start;

Console.WriteLine("{0}, {1}, {2}", test1[zz], test2[zz], test3[zz]);

}

Console.WriteLine("{0}, {1}, {2}", test1.Average(), test2.Average(), test3.Average());

Console.ReadKey();

To test this, run this code in release mode (plus Ctrl-F5, in Visual Studio).

x64 CPU platform results:
Test 1) 175ms
Test 2) 154 ms
Test 3) 155 ms

x86 CPU platform results:
Test 1) 198 ms
Test 2) 161 ms
Test 3) 169 ms

Test 1 uses an generic expression to 'cast' a numeric string array to a List of type Int32.
Cute line, isn't it?
But unfortunately, as has been said, the LINQ expression, still is a bit slower than the non-linq versions.

How much slower when we deal with integer math and avoid any parsing overhead?

Now if we replace the int.Parse() statement by a silly integer operation, such as
intList = intvalues.Select(p => p -1 ).ToList(); we have to increase the loopcount to 10,000,000 to get the workload to any significance. Now we measure plain LINQ performance.

x64 results:
Test 1) 269 ms
Test 2) 125 ms
Test 3) 128 ms

x86 results:
Test 1) 276 ms
Test 2) 126 ms
Test 3) 121 ms

Conclusion:
I expect over time that compilers become more and more smarter and can optimize even better LINQ expressions.
However, as we saw in the first example, int.Parse already flattened the results and the relative slowness of LINQ greatly.
Parsing and converting data in loops, is something we constantly do when we deal with XML and databases. So when the workload within the loop increases, the overhead of LINQ expressions quickly become no important factor.

So, for shorter code, I would not hesitate to use those expressions as in Test 1.
In a real life business application, the performance of loops really does not determine the final user experience. It is (e.g.) how we access a database or other resources, such as XML.

It would be another story, if we e.g. were doing 3D math animations, where C++ would be an obvious choice.

Howto program a LINQ expression which effectively does an aggregate subquery with optional cardinal relationship

eprogrammer — Tue, 18 Mar 2008 22:02:00 GMT

LINQ! Yes, Also I fell in love with linq.

So here is my first try. And as you fans know, I like to dig into subjects.

Maybe, the title is a little incorrect, but I wanted a query that returns one record, using a subquery in one statement!

Using SQL syntax, this would look like the query just below.: Yes, It seems I can dream SQL, but it was shocking to see how I underestimated the LINQ syntax which took some extra hears from my head.

The query returns events, that have not already been booked full. (There are still some places left)

SELECT [t0].[id], [t0].[maxNumberofParticipants], [t0].[OwerId], [t0].[Description], [t0].[StartTime], [t0].[EndTime],
[t0].[orderId] FROM [dbo].[Activity] AS [t0]
WHERE ([t0].[OwerId] = @p0) AND ([t0].[maxNumberofParticipants] > @p1) AND ([t0].[maxNumberofParticipants] > (ISNULL((
    SELECT SUM([t2].[value])
    FROM (
        SELECT [t1].[countOfPersons] AS [value], [t1].[activityId]
        FROM [dbo].[ActivityParticipant] AS [t1]
        ) AS [t2]
    WHERE [t2].[activityId] = [t0].[id]
    ),0)))

I could make this a stored proc, and execute this easily. But that was in my previous life.

So, how to express this using a LINQ query?

The trick with the ISNULL function is to -cast- the countOfPersons field, to a nullable type! Since the GetValueOrDefault() is available only to nullable data types we must cast it to an int? datatype.
The LINQ provider, will translate it finally, when it sends the actual SQL to SQL Server using TSQL function 'COALESC'.
bt.w., it will not use the ISNULL function.

public IEnumerable<Activity> getActivityParticipableByOwnerWith(Guid ownerGuid)
{

var query = from a in Activities
where a.OwerId == ownerGuid && a.maxNumberofParticipants > 0 && a.maxNumberofParticipants >
ActivityParticipants.Where(aid => aid.activityId == a.id).Sum(aid => (int?)aid.countOfPersons).GetValueOrDefault(0)
select a ;

return query;
}

Kuddo's to Khaled Moawad, who very patiently helped me to improve the syntax. b.t.w. guys/girls. Always try it hard yourself, before you ask the global community for support. That makes your brains retain better :)

My next goal is to make LINQ like a natural language for me, like SQL was :)

Howto loop through each element on a SafeArray with an unknown number of Dimensions?

eprogrammer — Sat, 22 Sep 2007 23:03:00 GMT

I thought that the subject ‘SafeArrays’ were really from the previous age and there was really nothing new about them, I could tell you , that was not already known.

So sit back and listen, what I am going to tell you, has been decided, in a dark hole, were some Microsoft Nerds must have thought that our programmers' live was too easy. So they modified the way the old variant arrays from the COM era were stored in memory.

Which Windows editions are involved in this modification? I don't know exactly. Anyway, Windows 64 bit edition (x64) really is subject to this, while Windows 2003 x86 (32 bit) is not. And don't worry too much, if you only use Ole Automation API calls, and not like I did, directly manipulated the SAFEARRAY storage area, your hard working code at your customers site, still should work

So, let’s figure what has changed by looking at the code below which very common.

SAFEARRAYBOUND bounds[1];

bounds.cElements = 10;
bounds.lLbound = 0;

SAFEARRAY *psa = SafeArrayCreate(VT_VARIANT, 1, &bounds);

This creates a variant array, that is compatible with scripting, similar to
Redim myArray(9) ' 0 to 9 is ten elements.

But before the array storage memory layout modification that I'm talking about,

LONG elSize = SafeArrayGetElementSize(psa); would return 16 (since sizeof(VARIANT) obviously equals that) but on Windows x64, this returns 24. Possibly, the alignment still is 16, but this makes me suspicious. Why did Microsoft change this? So I want to be sure it works independently of the Windows version or future features.

// code below gives an impression how to loop through an ‘unknonn dimension sized Safe Array, in this case the variant type is VT_VARIANT. Don’t use it. It’s faulty now on modern Windows systems.

LONG lElements = 0;

for (LONG x = 0; x < cDims; x++)

{

SafeArrayGetLBound(psa, x + 1, &lbound);

SafeArrayGetUBound(psa, x + 1, &ubound);

lElements += (ubound - lbound + 1);

}

hr = SafeArrayAccessData(psa, &psadata);
if (hr == S_OK)
{
                VARIANT *myvarray = static_cast<VARIANT *>(psadata);
                for (LONG els = 0; els < lElements && hr == S_OK; els++)
                {              // do something easy with the element
                               VARTYPE vt = myvarray[els].vt;
                }
                SafeArrayUnaccessData(psa);
}
The code above, would work to go through all elements for –any type of-SafeArray, VT_UI1, VT_BSTR, VT_VARIANT, because we assumed, for instance, that a VT_UI1, would be one byte long, isn’t it? And a BSTR Safe Array, would be a memory block, of BSTR pointers. And a VARIANT array, would have been a block of elements, consisting of VARIANTS.

So the code above, just worked, and looks in fact, pretty simple, fast and elegant.
Why so? Because it avoided the task to construct the indices one by one, and to fetch the element by using SafeArrayGetElement(psa, rgindices, outputvalue).

This one surely works, but has two important disadvantages,
1) when you deal with a known 3D or 2D sized-array, it's easy to fill the rgIndices in a loop, but if the dimensions are unknown, it would be required to iterate through the elements by other means. So you’re up to do some nasa stuff! J.
2) SafeArrayGetElement is relatively slow, since it copies the out value and you need to release the output (such as variants and strings). It’s like pumping around lots of memory, especially when the array is huge.

To get this working, I had to refresh my knowledge of some informatics school I did in the past, about simple math, about carry over on signed numbers. Since SafeArrays have different lowerbounds and upperbound ranges per dimension, you cannot simply multiply by a known row size, to initialize it. But anyway, to make a longer story shorter, and I might lack the correct choice of words, for things that I technically just ‘see’, I wrote the code for you. It’s pretty cool, I could not find such code through Google. J
Some tips. I decided to avoid reading the pointer to the safearray descriptor at all, because I saw some unexplainable swapping of rgsaBounds. Better use the API if there is one!

// assume psa to be of SAFEARRAY and this code is using ATL version 8

LONG cDims = SafeArrayGetDim(psa);

//we ‘rebuild’ the bounds by using the API, not by reading the psa structure directly to avoid unclear behaviour
CTempBuffer<SAFEARRAYBOUND> psaBound(cDims);

CTempBuffer<LONG> rgIndices(cDims);

LONG dimPointer = 0; // our dimension pointer, we go from left to right to build up the rgIndices

LONG currentEl = 0, ubound, lbound;

for (LONG x = 0; x < cDims; x++)

{

SafeArrayGetLBound(psa, x + 1, &lbound);

SafeArrayGetUBound(psa, x + 1, &ubound);

psaBound[x].cElements = ubound - lbound + 1;

psaBound[x].lLbound = rgIndices[x] = lbound;

}

// locking is not optional, it is needed.

SafeArrayLock(psa);

for(;;) //termination is decided within the loop

{

if (rgIndices[dimPointer] <

(LONG)psaBound[dimPointer].cElements + psaBound[dimPointer].lLbound)

{

VARIANT* pVar ;

// use the fast version instead of SafeArrayGetElement!

hr = SafeArrayPtrOfIndex(psa, rgIndices, (void**)&pVar);

if (FAILED(hr))

MYBAILOUT(hr);

rgIndices[dimPointer]++;

//this terminates the for as soon as we reached the last array element

if (++currentEl == lElements)

break;

}

// our carry on overflow stuff goes from left to right

else

{

while(rgIndices[++dimPointer]++ ==

(LONG)psaBound[dimPointer].cElements + psaBound[dimPointer].lLbound)

{

}

//reset previous cols to initial lowerbound from left to

// most right carry position

for (LONG z = 0; z < dimPointer; z++)

rgIndices = psaBound.lLbound;

// if carry has been done, we start counting on left again

dimPointer= 0;

}

To visualise this, I think it’s usefull to dry test this using a matrix.

Imagine, we have a script, that was created by your customer, in VBSCript and youre superpower, martian CPP needs to do something with this data.

So, the Customer code could be:

Redim MyArray(3,2)

How would our dynamic rgIndice be iterated?

rgIndices would follow this pattern.

Left dimension	Right dimension	Absolute element position
0	0	0
1	0	1
2	0	2
3	0	3
0	1	4
1	1	5
2	1	6
3	1	7
0	2	8
1	2	9
2	2	10
3	2	11

Of course, the algorithm, would go through any array, with any dimension.

Now have much fun with this code, if you needed it in your code. Don’t forget to add error handling which I left out to keep it short. And sure, you could write some C# stuff, for your COM interop to deal with array marshaling as well.

If this code was very useful for you, don’t forget to pay a visit to a component that uses this handy trick at http://www.nieropwebconsult.nl/asp_session_manager.htm

HttpWebRequest on DotNet 2.0 driving you crazy for a B2B request? Disable ServicePointManager.Expect100Continue first!

eprogrammer — Tue, 24 Jul 2007 16:52:00 GMT

Imagine, you have written a succesfull gateway to say, the European Community to check the validity of a VAT number.

It always works, but suddenly it does not work anymore. What's up? Could it be that some service pack modified the behaviour of the HttpWebRequest (including DotNet 2.0?) Sure it is! see http://support.microsoft.com/kb/915599

This posting might spare you several hours. The idea of the Expect100Continue setting is, that postdata is sent to the webserver in a separate post sequence package. But not all web servers like IIS (sure I'm MVP ) are full featured so in this case, this feature was hard to detect, only by using Netmon, I could figure what the HttpWebRequest was doing under the .NET runtime hood.

The Uri to the European VAT check is http://ec.europa.eu/taxation_customs/vies/

And it does a POST request to viesquer.do
(the previous obsolete URL was http://europa.eu.int/comm/taxation_customs/vies/cgi-bin/viesquer)

It had worked before because it just dit a GET request instead of a POST.

The steps that I walk through normally to write such a gateway,

opening my browser
Fill the form
Start Netmon 2.1 (or higher)
Post the data
Stop Netmon and filter on the HTTP protocol.

Now it's up to you to emulate the postdata and be sure that the character encoding is according to the supported one. In my case, I assume that UTF-8 is the worldstandard (it should work for most sites).

The code below is technically correct for the mentioned purpose but it performs no validation checking.
If you wish more flexibility some more work has to be done.

static bool doVatCheck(string vat, string state)

{

string urlQuery = @"http://ec.europa.eu/taxation_customs/vies/viesquer.do";

//important! The WebLogic Server 8.1 SP3 clearly does not support IETF RFC 2616 Section 10.1.1.

// so we disable the expect100 header and HTTP behaviour

ServicePointManager.Expect100Continue = false;

HttpWebRequest req;

StreamReader read=null;

Encoding enc = System.Text.Encoding.UTF8;

MemoryStream sw = new MemoryStream();

advancePos(enc, sw, "ms"); //member state

advancePos(sw, '=');

advancePos(enc, sw, state);

advancePos(sw, '&');

advancePos(enc, sw, "iso"); //same as member state, ISO country code

advancePos(sw, '=');

advancePos(enc, sw, state);

advancePos(sw, '&');

advancePos(enc, sw, "vat"); // 12no VATno. Do not submit dots or spaces

advancePos(sw, '=');

advancePos(enc, sw, vat);

req = (HttpWebRequest)HttpWebRequest.Create(urlQuery);

req.Method = "POST";

req.ContentType = "application/x-www-form-urlencoded";

// optional setting, UserAgent. A firewall could block if no browser is detected

req.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)";

long contLen = req.ContentLength = sw.Position;

Stream str = req.GetRequestStream();

str.Write(sw.GetBuffer(), 0, (int)contLen);

str.Flush();

try

{

read = new StreamReader(req.GetResponse().GetResponseStream(), enc);

string buf = read.ReadToEnd();

read.Close();

return buf.IndexOf("Yes, valid VAT number") >= 0;

}

catch (WebException ex)

{

//ex.st

string errr = (urlQuery + ex.Message);

}

return false;

}

static void advancePos(Encoding enc, MemoryStream sw, string val)

{

byte[] buf = HttpUtility.UrlEncodeToBytes(val, enc);

sw.Write(bufje, 0, buf.Length);

}

static void advancePos(MemoryStream sw, char val)

{

sw.WriteByte((byte)val);

}

ATL: Tiny but good Improvements on Visual Studio Sevice Pack 1 for ATL.

eprogrammer — Mon, 25 Dec 2006 10:35:00 GMT

I'm glad to see, that MS still did not get rid of ATL and continued to support us, that's those guys, who think that .NET is really awful, but not the holy grail :)

If you want to see it yourselfs, get a copy of windiff.exe or just run it, and compare your directories. It's a very handy tool, to compare source codes!

So, I compared some features on ATL. Quickly I found some differences in atlcomcli.h (I did not check everything however) and the improvements are OK!

Another part of the ATL source code, seems related to HTML and internet (ISAPI). Lots of checks and code has been added to make sure your precious HTML / encoding etc is kept in tact.

Well, which improvements? As you might know that ATL is all, mainly about writing non-UI unmanaged code, such as COM components or using powerfull small sized wrappers around kernel-items like security, string management, etc.

At first, finally, I found that MS recognized that SafeArrayGetVartype is flawed, since it does not really fetch the VARTYPE of the array in all situations. So they wrote AtlSafeArrayGetActualVartype.

Another things is CComVariant::Clear() which was a dangerous function to use! Why and when? Because the function it wraps, is VariantClear and variantClear does only set vt to VT_EMPTY, but it does not 'zero' the rest of the VARIANT struct. Some programs, do expect in/out variables, and in the case that it is not always testing for the vt (variant type) and reallocates the CComVariant instance, it might erronously reallocate 'freed' or 'zombie'-pointers.

So my advise is to never use CComVariant::Clear() but use CComVariant::ClearToZero() now to avoid a case of reallocating zombie data!

Another handy improvements is a new overloaded method on the WriteToStream member function.
It is CComVariant::WriteToStream(IStream *pstr, VARTYPE vt);

So, if you write the current variant to a certain stream, you can convert it to a BSTR (for instance) using this extra new parameter..

Then we got some important bugfixes in atldb.h and atldbcli.h some annotation and datatype and even template fixes.

Lets see atlutil.h. Lots of new helper functions have been added. AtlStrToNum and functions that help to convert and to support the conversion to and from __int64 (LONGLONG) datatype. Normally, I always had to lookup for such functions into the VC function library and to add some wrappers around them.

Once I checked this all, and I recompiled one of my CPP, ATL projects, the size became just slightly bigger. But who cares? If this is all about more robust and safe code, I'm not disappointed by the Sp1 for VC on Visual Studio 2005.

(I was disappointed, when MS deprecated a lot of syntax without any announcements since of Visual Studio 2003)

HOWTO: Associate a custom WKGUID (well known guid) to a custom Container

eprogrammer — Thu, 05 Oct 2006 11:05:00 GMT

Active Directory and ADSI (ldap in fact) have many unutilized features that, if the APIs would explain better be used much better!

Let me draw a situation for you.

Imagine you have an app, that is distributed and sold among international customers (congrats for that by the way J). Now there could happen 2 things, or 3 if nothing happens is a count as well).

1) Your company suddenly got sold out to a rich guy or girl and now everything gets renamed including your ‘custom company container’.
So cn=ourcompany data,cn=Program Data,dn=nwtraders,dc=msft
Must become (because your boss asks you to do so!)
cn=thenewcompany data,cn=Program data,dn=nwtraders,dc=msft

2) Some dn (distinguished Name) is subject to translation. Eg:
cn=Program Information,cn=etc blah blah
must be translated (because your boss asks you to do so J ) to
cn=Information du programme,cn=etc blah blah

In both situations 1 and 2 you’ll have to keep a list of paths per language and many companies of course, understand this is a difficult and risky task, so they might choose to keep up with a single international English name.

Note: The WKGUID protects against renaming or translating, but it is not meant to ‘protect’ against moving your container within Active Directory)

Why should you accept this risk if Active Directory supports immunity against renaming this out of the box if you associate a WKGUID?

However there is no obvious documentation about this and you just should know that setting this property more or less is hidden through usage of IDirectoryObject while ADSI /scripting/vb6 environments were not able to use this interface.

Worse, the sample at the MSDN might be working but goes lowest by using the ldap_connect API within a ADSI call (that’s rather dirty) instead of using CLSID_DNWithBinary and the sample is flawed with leaks but let’s not bash the writer, I’m not intending to do so).

(update) b.t.w. in the attachment temp.zip you'll find full source code for the sample. Note that Active Directory has a bug that makes custom WKGUIDs useless. It simply cannot find your custom WKGUID. I reported this bug to Microsoft.

How could you ever figure that WKGUID and it’s query syntax is related to the following attribute: ‘otherWellKnownObjects’?J.

This sort of documentation, it's complexity in Active Directory on LDAP makes it hard to see any utilization for this feature.

I hope to support MS-es Active Directory (that I love, just as IIS and SQL server) usage and ease in practice by posting the following sample code.

Note that this code is not ‘well-formed’ and ‘error-proof’ but it works and gives you an idea.

The logging (debug feature) is done through the logging module posted just before this posting.

Now how do we profit from this feature?

Imagine you have created through an LDIF or through code a container object

cn=our CompanyData,cn=Program Data,dc=nwtraders,dc=msft

1) Now we associate ‘our CompanyData’ with the ‘otherWellKnownObjects’ property using a custom hexadecimal guid “81a3469a653959419309b33e27bdd2c9”!

2) Eg: WriteADSAttributeDnWithString([ourcompnayCN], L”cn=our Company Data,cn=Program Data,dc=nwtraders,dc=msft”, ourGUID, ADS_ATTR_APPEND

3) Now you can query your company data like this, no matter your company is being renamed in futureJ, through the following syntax: LDAP://<WKGUID=8a3469a653959419309b33e27bdd2c9,cn=Program Data,dc=nwtraders,dc=msft>

Normally the dn for Program Data is WKGUID-ed by Microsoft as well! The Program Data container should be reliably formatted as L"LDAP://<WKGUID=%s,%s>", GUID_PROGRAM_DATA_CONTAINER_W, L”dc=nwtraders,dc=msft”)

Note: After you usage of the WKGUID or the GUID- syntax, you must resolve the fully qualified dn by using the ‘distinguishedName’ property and refetching your Actife Directory object before you go on with it.

Note: You would wish you could set the objectGUID attribute at creation of your object instead of the WKGUID. Unfortunately, this value is generated by Active Directory itself.)

STDMETHODIMP WriteADSAttributeDnWithString(

IADs *piADs,

PCWSTR dn,

PCWSTR guid)

{

CComVariant v;

CComPtr<IADsDNWithBinary> dnWithBin;

CComBSTR assocDn(dn);

dnWithBin.CoCreateInstance(CLSID_DNWithBinary);

v.vt = VT_UI1 | VT_ARRAY;

hr = ConvertHexGuidToArray(guid, &v.parray);

hr = dnWithBin->put_BinaryValue(v);

hr = dnWithBin->put_DNString(assocDn);

CComBSTR attribute( L"otherWellKnownObjects");

v.Clear();

v.vt = VT_DISPATCH;

dnWithBin.QueryInterface(&v.pdispVal);

hr = pADs->Put(attribute, v);

hr = pADs->SetInfo();

return hr;

}

// converts hexadecimal string to a octet encoded byte array

STDMETHODIMP ConvertHexGuidToArray(PCWSTR hexGuid, LPSAFEARRAY *sa)

{

if (hexGuid == NULL) return E_INVALIDARG;

int hexLen = (int)wcslen(hexGuid);

HRESULT hr = S_OK;

CTempBuffer<CHAR> sHex(hexLen);

int loopLen = hexLen;

while(loopLen-- != 0)

sHex[loopLen] = (CHAR) hexGuid[loopLen];

SAFEARRAY *temp= SafeArrayCreateVector(VT_UI1, 0, hexLen / 2);

if (temp == NULL)

return E_OUTOFMEMORY;

PBYTE dst ;

hr = SafeArrayAccessData(temp, (void**)&dst);

int dstLen = hexLen /2;

if (hr == S_OK)

{

AtlHexDecode(sHex, hexLen, dst, &dstLen );

hr = SafeArrayUnaccessData(temp);

*sa = temp; //return the array

}

return hr;

}

[ATL, CPP] How to log to a machine global logfile from different threads and processes.

eprogrammer — Sun, 01 Oct 2006 14:57:00 GMT

Each self-respecting programmer and software team uses logging features.

In my current job on ASP.NET, each click, every navigation and message is logged. Very handy indeed because you would like to support your customers.

For a classic C++ project this is not so easy to do. You can use ATLTRACE2 or AtlTrace and these macro's have the advantage that at release time, they won't stuff your code with unnecessary statements.

However, in case you have a support incident on your code that runs with a client, you'll have to add tools or to deliver windbg.exe to read those statements and to hand over a debug dll or exe. And you have to instruct your customers to save the log to a file. I'm not happy at this of course, I might be mistaken and some C++ expert tells me how easy this could be done in fact. ;).

So I wrote such a class. It is tested on several processes (as asp can do, several w3wp.exe processes can load your COM dll) that write to a single log file.

So what do we need to care for?

Log to a single file from one or more processes that load my specific COM dll
Log to 1) Debug Output 2) a file 3) both, 4) none
If logging is switched off, it must not cause performance degration.
If we write to the file, we must synchronize, we use a Mutex.
Our code that utilizes this class, must (preferable) access a singleton instance of our class per DLL

Here comes the source...

class LoggingModule

{

public:

LoggingModule() ;

~LoggingModule();

//releases resources

void Close(bool deleteLogFile = false);

void Write(PCWSTR pszFormat, ...);

void set_Logging(int enable);

// 0 = %windir%\Temp, 1=%userprofile%\Local Settings\Temp

void set_TempLocation(int location);

int get_Logging();

private:

CAtlFile m_file;

//0 disabled 1 = to file, 2 = to Debug 3 = both

int m_LoggingEnabled;

int m_tempLocation;

HANDLE m_hMutex;

CComBSTR m_MutexName ;

//member variable, so we enable BSTR caching. A lot more efficient

CComBSTR m_bstrTrace, m_logFileName, m_fmt;

};
extern LoggingModule logModule;

// implementation of LoggingModule

LoggingModule::LoggingModule(void) throw() :

m_LoggingEnabled(0),

m_hMutex(NULL)

{

}

void LoggingModule::set_TempLocation(int location) throw()

{

m_tempLocation = location;

}

void LoggingModule::set_Logging(int enable) throw()

{

m_LoggingEnabled = enable;

if ((m_LoggingEnabled & 1) == 1)

{

m_logFileName.SetLength(MAX_PATH);

DWORD bufLen = GetModuleFileNameW(_AtlBaseModule.GetModuleInstance(), m_logFileName, MAX_PATH);

PathStripPathW(m_logFileName);

PathRenameExtensionW(m_logFileName, L".LOG");

//strip right length

m_logFileName.SetLength((unsigned int)wcslen(m_logFileName));

m_MutexName = L"Global\\";

m_MutexName += m_logFileName;

CComBSTR buf(MAX_PATH);

if (m_tempLocation == 0)

bufLen = GetSystemWindowsDirectoryW(buf, MAX_PATH);

else

bufLen = GetTempPathW(MAX_PATH, buf);

if (bufLen == 0)

{

buf.Format(L"error %d\n", GetLastError());

OutputDebugStringW(buf);

m_logFileName.Empty();

m_LoggingEnabled ^= 1; //disable file logging

return;

}

else

{

//strip right length again

buf.SetLength(bufLen);

buf += L"\\TEMP\\";

buf += m_logFileName;

// now m_LogFileName looks like C:\Windows\Temp\myDll.Log

m_logFileName.Attach(buf.Detach());

}

//Create EveryOne in a language independend way

SID_IDENTIFIER_AUTHORITY sia = {SECURITY_WORLD_SID_AUTHORITY};

CSid everyone(sia, 1, SECURITY_WORLD_RID);

// we must use a Security Descriptor, otherwise other w3wp.exe processes cannot

// inherit the mutex!

CSecurityDescriptor secDescr;

// ATL does not initialize this object at construction??

HRESULT hr = secDescr.Initialize();

if (hr == S_OK) hr = secDescr.Allow((PSID)everyone.GetPSID(), MUTANT_ALL_ACCESS);

if (FAILED(hr))

{

buf.Format(L"secDescr.Allow failed with %x\n",hr);

OutputDebugStringW(buf);

m_LoggingEnabled ^= 1;

return;

}

SECURITY_ATTRIBUTES SecAttrs = {sizeof(SecAttrs), secDescr, TRUE};

// create the mutex without owning it.

// if another process (w3wp) already did the creation

// we just ignore the error and m_hMutex stays nill

m_hMutex = CreateMutexW(&SecAttrs, FALSE, m_MutexName);

if (m_file == NULL || m_logFileName.IsEmpty())

{

hr = m_file.Create(m_logFileName,

FILE_GENERIC_WRITE,

FILE_SHARE_READ | FILE_SHARE_WRITE,

OPEN_ALWAYS);

if (SUCCEEDED(hr))

{

ULONGLONG sz;

if (SUCCEEDED(m_file.GetSize(sz)))

{

//it's a unicode-8 logfile

if (sz == 0)

{

BYTE PreAmble[] = {0xEF, 0xBB, 0xBF};

m_file.Write(PreAmble, sizeof(PreAmble));

}

//TODO: finish

else if (sz > 10000)

{

//truncate first 5000 lines and restart

}

m_file.Seek(sz);

}

else

{

buf.Format(L"Could not create %s, error %x\n", m_logFileName, hr);

OutputDebugStringW(buf);

// do not bother to write to the logfile

m_LoggingEnabled ^= 1;

}

else

Close();

}

int LoggingModule::get_Logging() throw()

{

return m_LoggingEnabled;

}

LoggingModule::~LoggingModule(void) throw()

{

this->Close();

}

///<sumarray> releases resources</summary>

void LoggingModule::Close(bool deleteLogFile) throw()

{

m_file.Close();

m_bstrTrace.Empty();

if (m_hMutex != NULL)

{

CloseHandle(m_hMutex);

m_hMutex = NULL;

}

if (deleteLogFile && !m_logFileName.IsEmpty())

DeleteFileW(m_logFileName);

m_logFileName.Empty();

m_fmt.Empty();

}

// this function writes the debugging information to the logfile

// it synchronizes on a mutex so all processes go through this bottleneck

// and will 'fight' for file access

// be sure not to enable such a thing in production

void LoggingModule::Write(PCWSTR pszFormat, ...) throw()

{

bool noFileAccess = false;

HANDLE mutResult = NULL;

if (m_LoggingEnabled == 0)

return;

else if ((m_LoggingEnabled & 1) == 1)

{

mutResult = OpenMutexW(MUTANT_ALL_ACCESS, FALSE, MUTEXNAME);

if (mutResult != NULL)

{

DWORD dwWaitResult = WaitForSingleObject(

mutResult, // handle to mutex

5000L); // five-second time-out interval

switch (dwWaitResult)

{

// The thread got mutex ownership.

case WAIT_OBJECT_0: break; //ok

// Cannot get mutex ownership due to time-out.

case WAIT_TIMEOUT:

// Got ownership of the abandoned mutex object.

case WAIT_ABANDONED:

OutputDebugStringW(L"error on LoggingModule::Write OpenMutex\n");

noFileAccess = true;

break;

}

else

{

m_fmt.Format(L"coult not create mutex to %s err(%d)\n", m_logFileName, GetLastError());

OutputDebugStringW(m_fmt);

noFileAccess = true;

}

va_list ptr;

va_start(ptr, pszFormat);

m_bstrTrace.Format(pszFormat, ptr);

va_end(ptr);

SYSTEMTIME st ;

GetLocalTime(&st);

//prepend debugstring with thread and time.

// eg 1040{tab}10:40:50:0599{tab}msg

m_fmt.Format(L"%d\t%02d:%02d:%02d:%04d\t", GetCurrentThreadId(),

st.wHour, st.wMinute, st.wSecond, st.wMilliseconds);

bool appendCrLf = !m_bstrTrace.EndsWith(L"\n");

m_bstrTrace.Insert(0, m_fmt);

if ((m_LoggingEnabled & 2) == 2)

{

OutputDebugStringW(m_bstrTrace);

if (appendCrLf)

OutputDebugStringW(L"\n");

}

// write only to the file if we have access

if (m_file != NULL && !noFileAccess && (m_LoggingEnabled & 1) == 1)

{

ULONGLONG nCurLen;

m_file.GetSize(nCurLen);

m_file.Seek(nCurLen, FILE_BEGIN);

if (appendCrLf)

m_bstrTrace.Append(L"\r\n", 2);

m_fmt.Attach(m_bstrTrace.ToByteString());

m_file.Write(m_fmt, m_fmt.ByteLength());

//clear buffer so we can be sure the buffer advances

m_file.Flush();

if (mutResult != NULL)

{

//release ownership

ReleaseMutex(mutResult);

//close handle (because it is a duplicate!)

CloseHandle(mutResult);

}

// in your main CPP file you create -one instance- of this class.

LoggingModule logModule;

Remarks about the code.

the CComBSTR code uses method that are not available by default. To use the super-power-CComBSTR replacement, see my other Blog posting about this class (expect over 3000% bstr performance improvements)
This class minimizes file access by prebuffering the debug string.
It will log to \%windir%\temp\nameofyourdll.log
It writes the log as in utf-8 format.
Fans of my code already know that I have abandoned win9x compatibility. This code runs only WinNT and higher.
It uses ATL. So if you use MFC for instance, you'll have to replace the CSecurityDescriptor class with an alternative or direct Win API equivalents (which I dislike for being so complex).
dependencies: <atlfile.h>, CComBStr2.h, <atlsecurity.h>, <security.h>

Kerberos Negotiate authentication on IIS sucks

EProgrammer Blog — Tue, 22 Aug 2006 22:23:00 GMT

I just had to say it! Yes, I was frustrated. Negotiate (through kerberos) on IIS sucks! I love free speech, especially if something said is simply true (Joe Kaplan agreed with me)! Of course, this is not an excuse to be rude to MS employees :), but they never would improve things, if we don't ask for it right? Why is Kerberos on IIS such a pain? I need an Intranet site, running ASPX to utilize integrated security. That's nice. So, I don't have to maintain another user database (bleeh, not again). Secondly, for my AD solutions, I just needed full security based on AD, and (again) not my own security mechanism. I hear you say: "What this fuzz about? It just works? Yes, it just works -as long as the credential on the current browser-IIS session- does not need to go any further than a page. For SQL Server, most developers, still would use standard security (and not pass-through authentication, which needs kerberos). But for Exchange-, ADSI-, or Active Directory enabled pages, pages that -really do something - with Active Directory, IIS and Kerberos really need a professor (Joe Kaplan, but his fee is too high for me :) ) in Windows-kerberos-science. Well, euh, it's easy, just 3 things to check! there is AD (Active Directory) support (does AD trust IIS+host for delegation?) IIS - support (does IIS support Negotiate?) Browser support (do IE support Negotiate and integrated logon?) And between the lines, you need to make sure (such as using setspn.exe) that it all is going to work. To get this done and configured, you'd better not be a third party intranet supplier! Microsoft, please, fix this. I mean, make it more easy for us. Let me just enumerate some knowledgebase articles that give some checklists. (See knowledge base articles below, note there are much more articles about this subject!) For a script, yummy for you, you might not have found this script before, because I'm just good :). What it does, is checking (enabling) the IIS server delegation. Note, using it is for your own risk! (ps: My setup scripts are preferable VBS because that just works without any version messup). What it does is actually shown in the picture. It checks the middle option. update at 14 sep 2006: Some companies, have disabled netbios features and computer browsing. So they solely have DNS and AD, but this makes IIS fail to use negotiate as well. It just seems that IIS has a lot of legacy network component dependencies. ' this checks this IIS server, to be trusted ' otherwise, Negotiate (Wdigest) through kerberos will -not- work! ' if you don't like all protocols to be trusted, you should manually correct this property ' for this IIS server. Sub SetThisIISServerTrusted() Dim nt, ds, ldapHost, info, accInfo, dnMe Const ADS_NAME_INITTYPE_SERVER = 2, ADS_NAME_TYPE_NT4 = 3, _ ADS_NAME_TYPE_1779 = 1, ADS_UF_TRUSTED_FOR_DELEGATION = &H80000 Set nt = CreateObject( "NameTranslate" ) Set info = CreateObject( "WinNTSystemInfo" ) Set ds = GetObject( "LDAP://rootDSE" ) ' the AD server that is serving us must be authorative enough ldapHost = ds.Get( "dnsHostName" ) nt.Init ADS_NAME_INITTYPE_SERVER, ldapHost ' computer name is by definition the netbiosname plus a $ nt.Set ADS_NAME_TYPE_NT4, info.DomainName + "\" + info.ComputerName + "$" dnMe = nt.Get(ADS_NAME_TYPE_1779) Set ds = GetObject( "LDAP://" + dnMe) accInfo = ds.Get( "userAccountControl" ) accInfo = accInfo Or ADS_UF_TRUSTED_FOR_DELEGATION ds.Put "userAccountControl" , accInfo On Error Resume Next ds.SetInfo If Err.Number > 0 Then WScript.Echo " Error at SetThisIISServerTrusted:" + Err.Description + ":" + Err.Source + ":" + Hex(Err.Number) End If On Error Goto 0 Set ds = Nothing End Sub PRB: "Access Denied" Error Message When Using ServerXMLHTTP to Access an Authenticated Site ms-help://MS.MSDNQTR.v80.en/MS.MSDN.v80/MS.KB.v10.en/enu_kbmsxmlkb/msxmlkb/291008.htm Enable negotiate on IE6 ms-help://MS.MSDNQTR.v80.en/MS.MSDN.v80/MS.KB.v10.en/enu_kbie/ie/299838.htm Troubleshoot IIS negiotiate 326985 http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/security/tkerbdel.mspx Enable negotiate on IIS ms-help://MS.MSDNQTR.v80.en/MS.MSDN.v80/MS.KB.v10.en/enu_kbiis/iis/215383.htm Enable negotiate using XMLHttp ms-help://MS.MSDNQTR.v80.en/MS.MSDN.v80/MS.KB.v10.en/enu_kbmsxmlkb/msxmlkb/314404.htm http://support.microsoft.com/kb/326985/...(read more)

Boost BSTR performance for free, by 3000%

EProgrammer Blog — Tue, 25 Jul 2006 11:20:00 GMT

You don't need to if you thought so :) use CString only to get the best of string manipulation within the C++ environment in a mixed COM environment. This CComBSTR replacement offers the most you need without having to cast strings forward and backward and loose performance. Expect your multithreaded and SMP performance to improve while still using native BSTR variable storage....(read more)

Howto: Dynamically Create Gradient Buttons using ASPX and .NET

EProgrammer Blog — Wed, 12 Jul 2006 18:08:00 GMT

If you ever might want cute buttons, independently of your clients browser and theme, you might create buttons by using some dynamic GDI based code. I found this solution, which costed just 2 hours programming not bad at all, and you might profit from it as well. This code, automatically wraps text, all using .NET power. It even can be improved, to support hover as well. B.t.w. on Windows Vista XAML supports this but we’re still on the internet man! So why not make our own buttons. Paste code below, onto an empty ASPX page (for instance button.aspx), and call use it through the following arguments (other tag arguments omitted for simplicity). <asp:ImageButton id=”myButton” ImageUrl=Button.aspx?t=Hello%20World&w=150&h=35” runat=”server”/> Syntax below is based on C# 2.0 The output might look like this(appConfig must contain the buttoncolors) public partial class button : System.Web.UI. Page { private static Color parsRgb( string rgbColor) { int red, green, blue; red = int .Parse(rgbColor.Substring(0, 2), System.Globalization. NumberStyles .HexNumber); green = int .Parse(rgbColor.Substring(2, 2), System.Globalization. NumberStyles .HexNumber); blue = int .Parse(rgbColor.Substring(4, 2), System.Globalization. NumberStyles .HexNumber); return Color .FromArgb(red, green, blue); } protected void Page_Load( object sender, EventArgs e) { System.Collections.Specialized. NameValueCollection req= Request.QueryString; //get height string h=req[ "h" ]; //get width string w = req[ "w" ]; // get text string t = req[ "t" ]; if (t == null || t.Length == 0) throw new HttpException ( "QueryString t not supplied" ); int hashCode = t.GetHashCode(); string checkEtag = Request.Headers[ "ETag" ]; if (checkEtag != null && checkEtag.Length != 0) { if (checkEtag == hashCode.ToString()) { Response.StatusCode = ( int )System.Net. HttpStatusCode .NotModified; Response.StatusDescription = "Not modified" ; Response.SuppressContent = true ; return ; } } req= System.Web.Configuration. WebConfigurationManager .AppSettings; string colrRadiantStart = req[ "btnBgRadiantStart" ]; string fontSize = req[ "btnFontSize" ]; string FontName = req[ "btnFontName" ]; string colrRadiantEnd = req[ "btnBgRadiantEnd" ]; string FontColor = req[ "btnFontColor" ]; System.Drawing. Color ocolorEnd, colorStart, colorFont ; if (colrRadiantStart != null && colrRadiantStart.Length == 6) colorStart = parsRgb(colrRadiantStart); else throw new HttpException ( "You must provide a valid btnBgColor hex rgb-code in appConfig" ); if (colrRadiantEnd == null || colrRadiantEnd.Length != 6) throw new HttpException ( "You must provide a valid btnBgColor hex rgb-code in appConfig" ); else ocolorEnd = parsRgb(colrRadiantEnd); if (FontColor == null || FontColor.Length != 6) colorFont = Color .Black; //default else colorFont = parsRgb(FontColor); int iH = int .Parse(h); int iW = int .Parse(w); Bitmap oBmp1 = new Bitmap (iW, iH); Graphics oGrp1 = Graphics .FromImage(oBmp1); // seems not to have effect oGrp1.CompositingQuality = CompositingQuality .HighQuality; oGrp1.InterpolationMode = InterpolationMode .HighQualityBilinear; LinearGradientBrush lgb = new LinearGradientBrush ( new Rectangle (0, 0, iW, iH), colorStart, ocolorEnd, LinearGradientMode .Vertical); oGrp1.FillRectangle(lgb, 0, 0, iW, iH); System.Drawing. FontFamily fntFam = new FontFamily (FontName); Font fnt = new Font (fntFam, float .Parse(fontSize)); StringFormat stringFormat = StringFormat .GenericDefault; //we must set this value, other wise text will default to left. stringFormat.Alignment = StringAlignment .Center; SizeF szf = oGrp1.MeasureString(t, fnt, new SizeF (iW, iH), stringFormat); //center PointF FPoint = new PointF ((iW - szf.Width) / 2, (iH - szf.Height) / 2); oGrp1.DrawString(t, fnt, new SolidBrush (colorFont), new RectangleF (FPoint.X, FPoint.Y, szf.Width, szf.Height), stringFormat); Response.ContentType = "image/jpeg" ; Response.Cache.SetETag(hashCode.ToString()); //Response.Cache.SetLastModified(DateTime.Now); Response.Cache.SetCacheability( HttpCacheability .Public); oBmp1.Save(Response.OutputStream, System.Drawing.Imaging. ImageFormat .Jpeg); Response.End(); } }...(read more)