Part 1 - Introduction
Part 2 - Basic Example
Part 3 - Complex Example
Part 4 - Final Notes
Bonus - Ajax History and the Memento Pattern
Extra Bonus - Issues with Opera

I dedicate this blog to Tomi, who brought this issue to my attention. Without I would be blissfully unaware that my ajax examples did not work with Opera.

To make a long story short, the basic Ajax history points that are demonstrated starting in this blog entry and on the site here fail miserably when used by Opera, even the most recent v 10. It would go forward once and then fail on either the next history point or going backwards. It worked fine if history was not stored.

At first I thought that it might have to do with Validation, so I turned off Event Validation and ValidateRequests but no dice. I tried modifying the LoadScriptBeforeUI setting on the ScriptManager thinking that maybe Opera was attempting to access the controls before they were instantiated. No dice.

Looking at the "Error Console" in Opera gave this confusing information:

JavaScript - http://www.myfriedmind.com/ajaxexamples/AjaxSimplehistory.aspx
Unknown thread
Error:
name: Sys.WebForms.PageRequestManagerServerErrorException
message: Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the server. The status code returned from the server was: 400
stacktrace:   Line 5 of linked script http://www.myfriedmind.com/ScriptResource.axd?d=Ca9Q30sQJzQkznL95cxsbDyIKgsvVPJZcb1rw8ROyNsMckgQG68w3ACHnEiANP
BR_VaW0NUFhahnNTwkTQZ39NfZ8sEeH0NKN9NzfqKtjhs1&t=40a63f28
    function(a,d,f){if(this._request===d.get_webRequest()){this._processingRequest=false;this._additionalInput=null;this._request=null}var e=this._get_eventHandlerList().getHandler("endRequest"),b=false;if(e){var c=new Sys.WebForms.EndRequestEventArgs(a,f?f.dataItems:{},d);e(this,c);b=c.get_errorHandled()}if(a&&!b)throw a}
.....

The key is that it was not returning the 200 that we all know and love, but a 400 status. Per this Msoft article (kb 247249) -

If the contents of a GET request are corrupt, then the server is unable to determine the URL or the host to which the GET request should be sent. IIS is unable to retrieve the host information from the GET request packet in order to look up the meta data for the custom error. This is by design. Errors that result from severely corrupted GET requests are not customizable.

Now I KNOW that they are not corrupt. It works perfectly fine with IE and Firefox. When I run it on Fiddler (http://www.fiddler2.com/) - my go-to tool for troubleshooting odd Ajax problems I do see the 400 returned. Note in the picture that the first three are for IE which work (all 200s) the second set of three is for opera - the final one being the 400 error.

When I look at the raw data of that entry it tells me that the response is that it is getting a Bad Request <Invalid URL> (see below). hmmmmm, should I trust it?

Hunting and pecking I find various entries dealing with Opera and its issues with Ajax, most of them from years ago. And then I discover this gem: http://www.webmasterworld.com/javascript/3195000.htm which has this notation near the end (italics mine)

opera has a rather annoying bug. This occurred in both 8 and 9: If the URL is exactly the same, the PHP file results are cached, and all the requests terminate as soon as the first result is returned. IE does the same, but I was able to fix it by spitting out a couple of "no-cache" headers. opera ignores these headers.

I fixed that by adding an "id=" parameter to the URL, which made each URL unique. This forced opera to stop caching.

Wha??? So I added a querystring to the end of my url (it does not matter what it is) and it worked! In other words http://www.myfriedmind.com/ajaxexamples/AjaxSimplehistory.aspx?x=y will work in Opera but http://www.myfriedmind.com/ajaxexamples/AjaxSimplehistory.aspx will not.

Now here is the odd part, and to display it I am going to direct you to a slight different simple ajax example I just whipped up -> http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx. I am also going to give you a behind the scenes look (via fiddler) as to what, exactly, Opera is 'requesting'. The main modification I did was to change the length of the text used for the history point (I am only going to store hour, minutes, seconds to expedite this) to make it shorter and easier to view.

Again http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx works for the first one and fails for the second.

First, let us look at what happens in IE per Fiddler (note that I only include the querystring here for comparison, this example works in IE without it).

• clicking on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y 
  Post /ajaxexamples/AjaxSimpleOpera.aspx
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=042004
• clicking on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx#&&myTime=042004 
  Post /ajaxexamples/AjaxSimpleOpera.aspx
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx#&&myTime=042006
• clicking on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx#&&myTime=042006  
  Post /ajaxexamples/AjaxSimpleOpera.aspx
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx#&&myTime=042007
• clicking on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx#&&myTime=042007
  Post /ajaxexamples/AjaxSimpleOpera.aspx
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx#&&myTime=042008

Now the Opera per Fiddler -

• Now adding a querystring on to the end - ex: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y works. But notice what is happening behind the scenes with each click
• click on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y
  POST /ajaxexamples/AjaxSimpleOpera.aspx?x=y
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041426
• click on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041426
  POST /ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041426
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041443
• click on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041443
  POST /ajaxexamples/AjaxSimpleOpera.aspx?x=y%23&&myTime=041426#&&myTime=041443
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041443
• click on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041443
  POST /ajaxexamples/AjaxSimpleOpera.aspx?x=y%23&&&myTime=041426%23&myTime=041443#&&myTime=041535
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=0414535
• click on http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=0414535
  POST /ajaxexamples/AjaxSimpleOpera.aspx?x=y%23&&&&myTime=041426%23&myTime=041443%23&myTime=041535#&&myTime=041537
  new url: http://www.myfriedmind.com/ajaxexamples/AjaxSimpleOpera.aspx?x=y#&&myTime=041542

Okay, okay, there was a long time between clicks (I was pasting it over), but do you notice anything different between the two (pay attention to the POST that is done via Ajax)? Internet Explorer ALWAYS Posts to the same URL - it ignores the hash entry. Opera prepends the previous hash entry after encoding it for the url, and so it gets longer and longer.

What is really, really odd is that Opera keeps prepending EVEN WHEN YOU HIT THE BACK BUTTON! So moving back and forth in your ajax history means that you are getting a longer and longer request entry. If you want to see this, snag fiddler -> http://www.fiddler2.com and try it. Your POST request gets longer and longer due to the prepending, but the URL does not reflect this at all. This ALL happens under the covers.

I finally went into Opera and tried turning off ALL caching (disk and otherwise). No luck! And when I set it to pretend to be IE it threw an error on the history point setting, claiming it was not asynchronous. I even went into opera:config under User Prefs and set the "History Navigation Mode" to 1 per this article http://www.opera.com/support/kb/view/827/ to prevent what it calls "fast history navigation". Still no dice! I even set the Opera to "Always Reload Https In History" and then connected via https to the page and that failed as well.

So why does adding a query string work? I honestly don't know. But this might be a clue - when it succeeded the hash was passed as a query string variable in Opera. When it failed, no query string was passed at all. There are a number of posts all over the web that refer to Opera caching when it should not, so I suspect that that may indeed be the issue - Opera is caching the page regardless of what it is told. Only by including the query string can you force Opera to not do whatever it is doing.

So there appear to be three solutions

1. Don't use Ajax history for Opera unless you use a query string (it might work in systems other than .net, I have not tested this)
2. Get Opera to fix the issue (good luck!)
3. Make sure you have a querystring, even a nonsense one, if your users will be using Opera...

Happy coding!

----------

Further notes:

This article -> http://cfis.savagexi.com/2007/06/12/opera-ajax-and-bugs talks about an issue with Opera rejecting status codes other than 200. However that is probably not the issue since it should be returning a 200 code anyway. Just something to keep in mind.

Now I should note assuming that it was a caching issue I added a bunch of code to prevent caching - including the ones below:

Response.ClearHeaders();
Response.AppendHeader("Cache-Control", "no-cache");
Response.AppendHeader("Cache-Control", "private");
Response.AppendHeader("Cache-Control", "no-store");
Response.AppendHeader("Cache-Control", "must-revalidate");
Response.AppendHeader("Cache-Control", "max-stale=0"); 
Response.AppendHeader("Cache-Control", "post-check=0"); 
Response.AppendHeader("Cache-Control", "pre-check=0"); 
Response.AppendHeader("Pragma", "no-cache"); 
Response.AppendHeader("Keep-Alive", "timeout=3, max=993"); 
Response.AppendHeader("Expires", "Mon, 26 Jul 1997 05:00:00 GMT");
Response.Cache.SetExpires(DateTime.UtcNow.AddMinutes(-1));
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetNoStore();

But again, the only thing that appears to resolve the issue is the inclusion of a query string.

For those of you just enter the IT 'biz, let me assure you that Hewlett Packard was once a great company. Good, reliable printers. Functional Drivers. Not the crap we are handed today. It is always sad to see a reliable company start to tube and I can only hope that this is a quirk, but I once again ran into an issue with their drivers.

We are using their Universal Print Driver because they have not come out with the necessary drivers for Windows 2008 for our printers (not to mention the issue with their bidirectional channel component) and came across a rather strange bug. Let us say that we are trying to print the following document from Word 2007 that has a watermark. It should look like this:

However, when printed from an XP machine we only get half the letters. It looks like this:

I verify that there are no correct drivers from HP (nope!) and then I try changing a setting - maybe "Send Truetype as Bitmap". Wow! Now we have the other letters, we just dropped most of the original ones that were showing.

So I roll back the driver from PCL6 (v 5.0) to PCL5 (v 5.0). And guess what. It works. PCL 5 works where PCL 6 does not.

A little (true) story. I was about to fly out of town so I took my wife's car into an oil-change place just to get that task done. While there the tech pointed out that the alternator belt was missing a tooth. Now I have changed more alternator belts in my life than you can shake a stick at, and I should know better than to have an oil-change place change my belts, but since I was in a hurry I figured to let them do it for me this time.

Oops.

When I get back I find out that it is squealing when you start the car. Hmm, maybe they need to tighten it. I take it back and they can't repair it. It works on tensioning pulleys in that car and they tell me they think that one of the pulleys is broken. So I take it to the dealer to fix. The rep sits down next me after they have loaded the car up and taken a look and says, "Well, it is kind of good news. The pulleys aren't broken, they simply put on the wrong belt - it is too large."

It seems to me that these "Universal" print drivers from HP fall into that category. What use is a functional engine if the belts that you put on it do not fit.

Come on, HP, spend some time on the belts. Please.

1. Users may need to remove/add the printer back for this to get pushed down.
2. This is NOT Printing Preferences. The same screens are there, but they will not fix this, although they should be changed as well.
   

If you have moved to Windows 2008 for your Print Server and have encountered slow printing to your HP Laserjets, the issue may be the driver.

According to this support document by HP the issue lies in the HP Bidirectional Channel component - namely hpzbid.dll and hpzbidXX.msi). You can read all about the symptoms/cause there but to make a long story short it appears that this lies with issues where it continually tries to reinstall the .dll and fails.

The solution, according to HP, is NOT to call up and get updated .dlls (they probably will not give them to you) but to use their updated Universal Print Driver (UPD) version 5.0. This changes the .dll to cioum.dll for the bidirectional channel control rather than hpzbid.dll. HP has no intention of updating hpzbid.dll so get used to it.

The symptoms are hard to miss (for example it takes 30 seconds just to view the properties of a printer on a client machine) so this one should not be hard to miss. Just remember to use the 5.0 version of the UPD.

Printers noted by HP:

• Laserjet 4250 series
• Laserjet 4350 series
• Laserjet 9040 series
• Laserjet 9050 series
• Laserjet 5200 series
• Laserjet P3005 series
  

After installing our clustered w08 Print Server I noticed that there was a particular Warning in the System Log. Event ID 4 "The print spooler failed to reopen an existing printer connection because it could not read the configuration information from the registry key S-1-5-18\Printers\Connections. The print spooler could not open the registry key. This can occur if the registry key is corrupt or missing, or if the registry recently became unavailable."

I looked in the registry and, no surprise, that key was missing. I hunted around a bit and found this entry. Basically to resolve this was fairly simple - add the key back in:

1. Open up the registry on the computer (I did it on all nodes individually)
2. Go to HKEY_USERS/S-1-5-18/Printers
3. Add a new Key called "Connections" (no quotes)
4. Right-click and select Permissions on the new key to verify that System has "Full Control"

Now I am not sure if this is an issue with Clustering or just a strange whacky event that happened. But if it happens to you, hopefully this will resolve it.

<rules>
  <rule>
    <path>http://YourFormsAuthSite/*</path>
    <type>FORM</type>
    <error_pages>
      <error_page>Logon.aspx</error_page>
    </error_pages>
    <auth_url>Logon.aspx</auth_url>
    <login_type>POST</login_type>
    <parameters>
      <param name="__VIEWSTATE">dDw0OTQzMjI0MjQ7O2w8UGVyc2lzdDs%2BPvhWhKKTnHpM3RIvgkgC9jJVpN%2Bg</param>
      <param name="Login1%24UserName">FormsAuthUserName</param>
      <param name="Login1%24LoginButton">FormsAuthPassword</param>
      <param name="Login1%24LoginButton">Log+In</param>
    </parameters>
  </rule>
</rules>

1. They have incorrect fieldnames (missing the Placeholders) and note the repetition of LoginButton for the Password portion of the XML demo. Obviously someone simply cut and pasted sections rather than pasting a complete, correct, XML
2. They do not have __EventValidation. Testing this with Fiddler emphasized the need for that
3. They do not have public="true" in their params which can be useful - public: If this value is not present, the parameter specified will be encrypted and stored in the search system. For encrypted parameters, the size limit is 1,024 characters. If you specify public = "true", the parameter will not be encrypted before storing in the search system. Also, the parameters size limit increases to 4,096 characters. 

• Make sure the entries on both sides of the params are htmlencoded - use http://meyerweb.com/eric/tools/dencoder/ if you need help...
• Remember that this DOES NOT do security trimming. You still need to setup an FBA security trimmer - see http://technet.microsoft.com/en-us/library/bb852172.aspx#moss12_SearchFormsAuth_ImplementSecurityTrimmer for info on that...

http://technet.microsoft.com/en-us/library/aa996343.aspx discusses means to grant access to mailboxes. The Console can grant it to individual mailboxes, but what if you want the whole kit and kaboodle? They mention using the Add-ADPermission like this from the Shell:

Add-ADPermission -Identity "Mailbox Store" -User "Trusted User" -ExtendedRights Receive-As

This seem to be fairly straightforward. For example:

Add-ADPermission -Identity "myServer\mySG\myDB" -User "myDomain\my.name" -ExtendedRights - Receive-As

But if you do that you get yelled at:

Add-ADPermission : myServer\mySG\myDB was not found. Please make sure you have typed it correctly.
At line:1 char:17
+ ADD-ADPermission  <<<< -Identity "myServer\mySG\myDB " -User "myDomain\my.name" -ExtendedRights Receive-As

The trick here is that in this case the "Mailbox Store" means something different than every other time I have run across that phrase. In this case it is looking for the AD Distinguished Name:

[PS] C:\Windows\System32>add-adpermission -identity "CN=InformationStore,CN=EX07ServerName,CN=Servers,CN=Exchange Administrative Group,CN=Administrative Groups,CN=Our Company,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=myDomain,DC=com" -User "myDomain\my.name" -ExtendedRights Receive-As

That works. Kind of intuitive, no? No? Well here is a way to find that beast:

1 - Install ADSI Edit (if you have not already) http://technet.microsoft.com/en-us/library/cc773354%28WS.10%29.aspx

2 - Open up "Configuration (NOT Domain) by selecting it in the "Select a well known Naming Context

3 - Drill down to (ready, take a breath)

• Configuration
• Your domain
• CN=Services
• CN=Microsoft Exchange
• CN=%Organization Name as stored in Exchange%
• CN=Servers
• CN=%Server Name that has the database%
• CN=%Mailbox Storage Name%
• CN="Database% (optional)
• Right Click and select 'Properties'

4. What you need to know is stored in distinguishedName. You can double-click and it will popup a textbox (as shown below). You can copy that, just DO NOT DELETE IT!!! This will give you the information you need to supply in the -Identity entry. You can also select a particular database if you so choose.

If you have been observant you will note that the DistinguishedName (which is what is passed into the -Identity variable) matches the path you drilled down. So theoretically, you do not need to go through this. Your entry should be something like:

CN=InformationStore,CN=%Exchange Server That Has Databases%,CN=Servers,CN=Exchange Administrative Group,CN=Administrative Groups,CN=%Your Exchange Organizational Name,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=%Your Domain%,DC=%your DomainExtension"

Good luck!