Thursday 26 June, 2008 (.Net | Fixes | Ramblings | Web)
I was just surfing around on http://forums.microsoft.com and got a yellow screen of death!
I must say I was slightly surprised. In web projects that I have been involved in we have always added two customErrors pages one to handle generic errors which redirects to an errorpage.aspx page and then a static html page errorpage.html which is only used when an error occurs on the dynamic error page... A sample configuration using location follows:
<configuration>
<system.web>
<customErrors mode="on" defaultRedirect="errorpage.aspx"/>
</system.web>
<location path="errorpage.aspx">
<system.web>
<customErrors mode="on" defaultRedirect="errorpage.html"/>
</system.web>
</location>
</configuration>
That way if we have a problem with our application that affects the entire site, for instance menu and navigational rendering, we can still show a nice error page with a message like "The site is temporarily unavailable, please try again in a few minutes."
Thursday 26 June, 2008 (.Net | Bugs | Fixes | Team System)
We have just had a major Active Directory issue that has affected the Team Foundation Server instance that all the developers at the client that I am working at use. The problem occured when some users where erased in the Active Directory and were subsequently recreated with the same user names. These new user accounts cannot access the Team Foundation Server.
A large part of the problem was solved by just removing users from TFS and then putting them back in again. This recreates all the wiring under the surface in TFS so that the users can access the server but all their existing workspace info, pending checkins and so on are lost locally yet exist in Team Foundation Server with a different Owner under the same user name... The only way to tell them apart is by their SID and that the original account may get suffixed with a number in workspace lists: AD\username:61.
My first thought was to remove all the workspaces and pending checkins and let people manually resynch their projects. When I clicked undo pending change for a bunch of changes in Attrice Sidekicks an unhandled exception popped up: "Object reference not set to an instance of an object". I just can't undo these changes, there is a clue to the problem when I try to unlock a changed file, I get an Unlock error:
Failed to unlock $/Project/Path/file (TF14061: The workspace COMPUTERNAME; AD\username does not exist.)
I can't search for workspaces by username either, even doing a simple TFSSecurtiy /i "ad\username" /server:TFSName for one of the affected accounts returns "Error: The identity cannot be resolved." Since the original accounts have been removed from Active Directory I cannot easily get hold of their SIDs for querying with TFSSecurity. Attempting to delete the workspaces from the command line return the following error:
TF14061: The workspace WORKSPACENAME;AD\username does not exist.
Things seemed pretty messed up... I found some clues as to what was required to get things working again:
http://support.microsoft.com/kb/948679
http://support.microsoft.com/kb/823278
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=454060&SiteID=1
According to the KnowledgeBase articles trying to create a new project while TFS is in this state may result in the following error:
TF30170: the plugin Microsoft.ProjectCreationWizard.WorkItemTracking Failed during task WITS from group WorkItemTracking
Basically Team Foundation Server has a bug that causes deleted accounts to not be resynched correctly and SharePoint doesn't handle recreated user accounts at all - you have to resynch them manually. Unfortunately in addition to this there is a bug in TFS SP1 which prevents TfsAdminUtilI from correcting the SIDS! You get the following error:
ERROR: Could not access database.
In the end I managed to correct all the problems, here are the steps required:
- Contact Microsoft Support and request the hotfix for http://support.microsoft.com/kb/934216
- Install the hotfix...
- Follow the steps in http://support.microsoft.com/kb/948679 to resynch the users SIDs in TFS
- Follow the steps in http://support.microsoft.com/kb/823278 to resynch the users in SharePoint
- Recycle the TFS App Pool to force an update of all users and groups in TFS.
Look out with users who have their workspaces mapped to "c:\documents and settings\" the new user accounts cannot necessarily access their old files there since they now log on with a new account (which just happens to have the same name).
Thursday 15 May, 2008 (.Net | Bugs | Java | Web)
I have been having some trouble lately trying to debug a .Net web service that I have constructed for a proof of concept. The scenario is that we have a Java application that calls a web service and the web service passes the call on to BizTalk for processing. Not a terribly complex scenario so I wasn't expecting much trouble setting up the POC. Unfortunately we have experienced some really strange problems. Calling the web service from a .Net client works without problems but when the exact same SoapEnvelope is used in the Java client through a proxy we get a "HTTP/1.1 400 Bad Request" error!
How is this possible? Well after much trial and error, searching the net and generally scratching my head I finally found a clue to the root cause of the error. One of the scenarios when "400 Bad Request" is returned is if the value of the content-length header is smaller then the actual length of the message body. I could not find a simple way to get IIS 6 to log the actual HTTP headers which were received and my favourite HTTP debugger Fiddler couldn't be used when the calls came from the Java client so it was very difficult to verify. The WSE input tracing showed a correct request and the application log contained the following unhelpful message
Process information:
Process ID: 5856
Process name: w3wp.exe
Account name: AD\serviceaccount
Exception information:
Exception type: HttpException
Exception message: Server cannot clear headers after HTTP headers have been sent.
I managed to get a nice raw HTTP dump sent to the application log by adding the following to my Global.asax
void Application_BeginRequest(object sender, EventArgs e)
{
//save position for reset
long position = HttpContext.Current.Request.InputStream.Position;
string requestBody = new StreamReader(HttpContext.Current.Request.InputStream).ReadToEnd();
//reset the position
HttpContext.Current.Request.InputStream.Position = position;
EventLog.WriteEntry("Service HTTP Dump", Server.UrlDecode(Context.Request.Headers.ToString()).Replace("&", Environment.NewLine) + Environment.NewLine + requestBody);
}Using this I could verify that it was in fact an incorrect content-length in the HTTP header which was causing the problem. Using Notepad++ and Fiddler I could see that the actual content-length was 634 using CRLF and 631 using only CR. The Java client was specifying 631 but the .Net web service was actually receiving 634. With the help of Telnet I could send in a call with 631 characters and CR as line-end and verify that the .Net web service handled the request properly. For the sake of clarity this is a sample Java HTTP header:
POST /path/service.asmx HTTP/1.1
Host: servername:80
Cache-Control: no-cache
Connection: close
Pragma: no-cache
Content-Type: text/xml; charset=utf-8
Accept: application/soap+xml, application/dime, multipart/related, text/*
User-Agent: Axis/1.1
SOAPAction: "http://schemas.example.com/2008/04/22/Service:ValidateRequest"
Content-Length: 631
The same request from a .Net client:
POST /path/service.asmx HTTP/1.1
Host: servername:80
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client Protocol 2.0.50727.1433)
Content-Type: text/xml; charset=utf-8
SOAPAction: "http://schemas.example.com/2008/04/22/Service:ValidateRequest"
Content-Length: 634
Expect: 100-continue
Both requests had a length of 634.
More info on the exact nature and calculation of the HTTP headers are in the RFC and in section 3.7.1 of the RFC valid line endings for the message body are defined. Basically it says that CR, LF or CRLF should be valid as long as they are used consistently but CRLF should still be treated as two characters for content-length (the spec doesn't explicitly say that but I presume that it is required). So the .Net web service has a correct behaviour, the specification also says that content-length may be omitted in HTTP 1.1 although it should be honoured if it is specified. Since it is required in 1.0 and it is usually very easy to calculate it isn't something that you usually have to think about trying to omit and it is hidden in the web calling infrastructure of Java and .Net.
I am not sure where our error is introduced. It could be when the original message is constructed in Java, whatever library is used to calculate the content-length could do so incorrectly (not likely). A more probable source is that the message is constructed with correct line-ends in the body (CR or LF) but that the intermediary proxy recodes the call with new line-ends (CRLF) without updating the content-length.
How can we fix it? I believe that there are three possible solutions for the problem (we haven't solved it yet).
- Remove the proxy, should be the easiest but due to the network configuration that isn't possible at the moment.
- Change the way that the Java client creates it's content so that it uses CRLF by default thereby forcing a correct larger content-length.
- Use the Application_BeginRequest method in Global.asax or an HTTPHandler to somehow rewrite the input stream or recalculate the content-length. At the moment I am not sure that either is possible.
Update
We managed to remove the proxy (which was actually part of a VPN connection) and our troubles disappeared.
Tuesday 15 April, 2008 (.Net | Blogging | Bugs | Fixes | Web)
I seem to have managed to get server pings from dasBlog to work in medium trust! This has been a major issue for me previously, not as much of an issue now that I primarily use off-line tools but it is still great to have it. The key is that originUrl in the medium trust settings supports regular expressions! More info on Haacked, which is where I found the solution. Just to make things clear:
<trust level="Medium" originUrl=".*" />
will allow your web site to send web requests to any external site...
Tuesday 15 April, 2008 (.Net | Blogging | dasBlog)
It turns out that it really was very simple to upgrade to dasBlog 2.0 and ASP.Net 2.0. I did the ASP.Net upgrade first simply by changing which version of .Net to use. dasBlog 1.9 seemed to keep on working without a hitch which meant I could proceed with the upgrade process locally. I followed the instructions and uploaded all the files to my server...
Unfortunately I had missed a section that I had changed in my web.config which of course meant an ugly error page was the first thing that came up. In the upgrade instructions they point out that the most common cause of errors during an upgrade is problems merging changes in web.config so I could easily fix it guided by the detailed error message that I received.
Now it seems that most of the problems that I had with previous versions of dasBlog running under medium trust are gone. The only problem that remains is that the default configuration of medium trust won't allow dasBlog to ping or trackback to other sites, I can live with that!
Tuesday 15 April, 2008 (.Net | Blogging | dasBlog)
I am preparing to upgrade my blog to 2.0. Thats both dasBlog 2.0 and .Net 2.0.
It looks like this version should fix all of my previous issues with my setup, unless my host has done some weird .Net 2.0 medium trust setup, you never know... There is a guide on doing the upgrade install here. As far as I can see the process seems to be:
- Download & place all the files for you new version of dasBlog locally
- Download the content folder from your public site and place it in the local version of dasBlog
- Run the upgrader tool locally
- Merge changes in your current web.config and the new versions web.config
- Merge changes in your current site.config and the new versions site.config
- Upload all the local files overwriting existing files
Seems pretty simple. I also have to change the config of my host to use ASP.NET 2.0.
What could possibly go wrong... 
Monday 04 February, 2008 (.Net | Bugs | Fixes | Web)
Recently I was working on ASP.Net 2.0 Web Parts in a Virtual PC environment and ran across a strange exception. I had read that the Web Parts personalization database is separate from the membership and profiles databases but had not really thought about it further. Previously everything just seemed to work once I ran "aspnet_regsql" to create the aspnetdb database to handle all the data for the services.
In the VPC there was already a really simple Web Part Page that I wanted to test. I had not prepared the VPC myself and others had been using it before me (so I presumed that it would work) but no one had used it in a long while. When I attempted to login and access the Web Part page I received this exception:
Procedure or Function 'aspnet_PersonalizationPerUser_GetPageSettings' expects parameter '@TimeZoneAdjustment', which was not supplied.
I checked the aspnetdb database to see if there was something wrong there but the stored procedure did not contain a '@TimeZoneAdjustment' parameter... Some related forum discussions on the web indicated that it might be a problem with the solution and database being created under a pre-release version of .Net 2.0. I tried re-running aspnet_regsql to remove and recreate the aspnetdb database, I reinstalled .Net 2.0, I installed SP1 for .Net 2. Nothing helped.
It turns out that the default personalization provider for Web Parts uses a file based SQL Express database which is automatically created in the App_Data folder of the web application. This database had already been created using a previous version of the framework before I started looking at the solution. For the sake of confusion it is also named aspnetdb, removing this database from the App_Data folder solved the problem. When I logged in and opened the Web Part page the database was recreated with the correct structure and everything just worked!
Tuesday 09 January, 2007 (.Net | Team System)
Download the sample code.
I have tried different methods to move work items from one Team Foundation Server to another. The easiest method is doing it with Excel, but the problem is that I also want to keep all the work item history which Excel cannot do.
I found that the Revision property of each work item contains an array of complete copies of the work item as it appears at each revision. So iterating over each revision in order allows us to recreate each version that was saved! By setting the system time to the time of the original revision we can recreate a work item including all its changes, provided that we execute the code on our server so that the date changes are reflected when the work items are saved. An added bonus of iterating over each revision and saving them is that all the state changes are legal so we don't need to figure out how to get our work item to it's final state if we have complicated state transition rules.
If we execute our updates as a different user than the one that made the changes originally then each history entry will be tagged as "Edited by XXX on behalf of YYY". Unfortunately it appears that project reports are not updated with the historic data, all the new work items will be added to the reports the day that you import them.
The following code illustrated how I have copied almost all of the basic data from work items using revisions (unfortunately indentation was lost when I copy/pasted the code):
foreach (Revision r in wi.Revisions)
{
foreach(Field f in r.Fields)
{
if(f.ReferenceName == CoreFieldReferenceNames.ChangedDate)
{
System.Diagnostics.Debug.WriteLine(f.Name + " : "+ f.Value);
//Copy revision date
System.DateTime revDateTime = (System.DateTime)f.Value;
revSysTime.wDay = Convert.ToUInt16(revDateTime.Day);
revSysTime.wHour = Convert.ToUInt16(revDateTime.Hour);
revSysTime.wMilliseconds = Convert.ToUInt16(revDateTime.Millisecond)
revSysTime.wMinute = Convert.ToUInt16(revDateTime.Minute);
revSysTime.wMonth = Convert.ToUInt16(revDateTime.Month);
revSysTime.wSecond = Convert.ToUInt16(revDateTime.Second);
revSysTime.wYear = Convert.ToUInt16(revDateTime.Year);
}
if(f.ReferenceName != CoreFieldReferenceNames.History
&& f.ReferenceName != CoreFieldReferenceNames.WorkItemType
&& f.ReferenceName != CoreFieldReferenceNames.TeamProject
&& f.ReferenceName != CoreFieldReferenceNames.Id
&& f.ReferenceName != CoreFieldReferenceNames.IterationId
&& f.ReferenceName != CoreFieldReferenceNames.IterationPath
&& f.ReferenceName != CoreFieldReferenceNames.AreaId
&& f.ReferenceName != CoreFieldReferenceNames.AreaPath
&& f.ReferenceName != CoreFieldReferenceNames.CreatedBy
)
{
if(!f.IsComputed && f.IsValid)
{
destItem.Fields[f.Name].Value = f.Value;
}
}
}
System.Collections.ArrayList arrl = destItem.Validate();
if(arrl.Count > 0)
{
//Handle validation errors
}
else
{
GetSystemTime(ref currentSysTime);
SysTimeNeedsReset = true;
if(SetSystemTime(ref revSysTime) == 0)
{
throw new ApplicationException("SystemTime was not set!");
}
destItem.Save();
if(SetSystemTime(ref currentSysTime) == 0)
{
throw new ApplicationException("SystemTime was not reset!");
}
SysTimeNeedsReset = false;
}
}
You can download the code to the minimal WinForms app that I have created for copying work items here. The code is provided as-is with no guarantees or support...
Things that are not handled at all are: user mappings if the source and destination server have different users, area and iterations, links and attachments. There may be more things that are missing or don't work that haven't affected my setup.
Thursday 07 December, 2006 (.Net | Speaking | Tips | Web)
A couple of days ago I did my first big talk, a colleague and I held a 50 minute session on migrating from ASP.NET 1.x to ASP.NET 2.0 at DevDays 2006 in Stockholm. Luckily it was a big success! I credit our success almost entirely (obviously we had some part in it...) to Scott Hanselman, we found many tips and links on the topic of public speaking on Scott's blog. The most important tip and what we worked on most was "be prepared", we studied our subject vigorously the days before, preparing for any questions that the audience might ask. We also practised our talk, including all the demos, about 6 or 7 times to get the timing right and just feel confident with the content.
In order to Google-boost these great resources and to make it easier for myself to find them again I list them here:
http://www.hanselman.com/blog/content/radiostories/2003/01/22/scottHanselmansTipsForASuccessfulMsftPresentation.html
http://www.hanselman.com/blog/PresentationTipsPPT.aspx
http://www.hanselman.com/blog/PowerPointTipsBeyondBullets.aspx
http://www.toastmasters.org/pdfs/top10.pdf
http://sociablemedia.typepad.com/beyond_bullets/
http://www.venkatarangan.com/blog/PermaLink.aspx?guid=dab57735-2976-40d7-a5d0-2e641ddea515
http://www.presentationzen.com/
http://www.hanselman.com/blog/InSearchOfThePerfectMonospacedProgrammersFontInconsolata.aspx
http://www.hanselman.com/blog/ReadySetVSNETChrisKinsmanAHrefhttpwww.aspx
http://www.hanselman.com/blog/PresentationTipsForPeopleRunningVirtualPCOrVMWare.aspx
http://www.hanselman.com/tools
Wednesday 29 November, 2006 (.Net | Speaking | Web)
I will be speaking at DevDays 2006 here in Sweden next week on the topic of migrating Asp.Net 1.1 applications to Asp.Net 2.0. It is an interesting topic especially when you really start looking under the covers at what has changed at a lower level. The whole session will be recorded and may be made publicly available at a later date.
For anyone else who is interested in this topic these are some of the resources I have used for my presentation:
What's New in ASP.NET
ASP.NET 2.0 Internals
Codebehind and Compilation in ASP.NET 2.0
Master Pages in ASP.NET 2.0
Understanding Page Inheritance in ASP.NET 2.0
Migrating from ASP.NET 1.1 to ASP.NET 2.0
Tuesday 28 November, 2006 (.Net | Bugs | dasBlog)
Basically avoid changing the xml files under content for dasBlog, you will mess up your blog. I did this in an attempt to make a post that I started on the 7th but posted on the 8th go back to being on the 7th... First I just changed the CreatedDate in the content xml and this almost worked, the post would intermittently disappear from the site (and the file). Luckily I had made a backup of the content files before I did this so I could just put the post back up when it disappeared. I quickly realised that this was a suboptimal solution! So I moved the post over to a new file with the correct date in the name. This file was eaten up by dasBlog and mysteriously disappeared, although I didn't notice it for about a week. What had happened was that I had got the date for the outer element set to another day in conflict with another file. So dasBlog just kicked it. Once I had got the date right it still took several updates for the change to propagate. Now I hope I have saved all my posts!
Friday 24 November, 2006 (.Net | GTD)
I found a couple of other Two Minute Timers:
http://www.avesh.com/blog/TwoMinuteTimer.aspx
http://blog.brettkelly.org/?p=215
On lifehacker there is a reference to an article about beating procrastination, this is something that I have a problem with so I am going to try it out: Just start doing it but only do it for 10 minutes. After that decide if you want to continue or not. With this in mind I have released a new version of my timer with a 10 minute option...
I have deployed this as a ClickOnce application now so you can get automatic updates if you want. The new version is 0.2.2
Features:
Customisable opacity.
Tray icon.
Start a 2 or 10 minute timer from a context menu.
System requirements:
Windows 2000, XP (probably 2003 Server also but not tested)
.Net 2 (the install should download .Net 2 if you don't have it)
Planned features:
Customisable alarm behaviour (flash window, system sounds, audio files).
Custom count-down enter hour, minute, seconds.
Autostart up on login option
Download now
Disclaimer
The opinions expressed herein are my own personal opinions and do not represent
my employer's view in any way.
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