WCF URL Length Causing IIS 400 Bad Request Error - wcf

Question

I have a wcf webHttp endpoint and noticed today that when called httpGet with a long url ~364 total characters (http:// etc counted) IIS throws a 400 bad request error. Throwing a breakpoint in the code never gets reached. If I remove some parameters and have a url that is 354 the web service runs as expected.
I'm not sure where the issue is since urls can be like 2k. I'm not posting any data so I don't think I'm hitting a 4mb limit like from here
What gives?
Here's some wcf xml stuff.
<behaviors>
<endpointBehaviors>
<behavior name="REST">
<webHttp/>
</behavior>
</endpointBehaviors>
</behaviors>
<endpoint address="" behaviorConfiguration="REST" binding="customBinding" bindingConfiguration="jsonpBinding" contract="Interface"/>
<bindings>
<customBinding>
<binding name="jsonpBinding">
<jsonpMessageEncoding/>
<httpTransport manualAddressing="true"/>
</binding>
</customBinding>
</bindings>
<extensions>
<bindingElementExtensions>
<add name="jsonpMessageEncoding" type="Microsoft.Ajax.Samples.JsonpBindingExtension, service, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"/>
</bindingElementExtensions>
</extensions>
I just removed the callback function name which significantly reduced the size of the url and it still threw a 400 error. This makes me think that there is a WCF size limit on the text that can be sent in as a string parameter.
here;'s some Contract stuff
[OperationContract]
[WebGet(UriTemplate = #"{userName}/layer({layerName})returnAttributes({attributeList})where({attributeName})({op})({attributeValue})", ResponseFormat = WebMessageFormat.Json)]
[JSONPBehavior(callback = "callback")]
DojoGrouping GetAttributes(string userName, string layerName, string attributeList, string attributeName, string attributeValue);
the issue is with attributeList which can be comma separated list.
so with a url call like
http://../demo/layer(OfficialsLookup)returnAttributes(USHOUSE,US_Photo,US_Web,US_Name,SENDIST,SEN_Name,SEN_Email,SEN_Party,SEN_Photo,REPDIST,REP_Name,REP_Email,REP_Party,REP_Web,REP_Photo)utmX(430)utmY(4502)
it busts. But if i shorten the return attribute text then it functions properly.
I've added I added the following entry into the registry:
Key Name: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Parameters
Class Name: <NO CLASS>
Last Write Time: 1/25/2011 - 3:34 PM
Value 0
Name: UrlSegmentMaxLength
Type: REG_DWORD
Data: 0x200
I rebooted the machine after adding it and am still receiving the same error. Is this the correct spot to be modifying the HTTP.sys settings that WCF and IIS are using? Is there a way to test that WCF is being affected by this registry value?
Here is a related post with no answer but saying that the httpsys stuff did not fix a 64 bit server which is what we are using.
Related Post

Answer 1

To fix our issue we had to use the .NET 4.0 framework. We moved the web service to run under a .net 4.0 app pool and changed the target framework to 4.0. This caused the site to spit out url is too long error instead of just a bad request. After adding a web config entry in
<system.web>
added
<httpRuntime maxUrlLength="500" />
for max url length, the service is up and running as expected.

Answer 2

WCF uses HTTP.sys to handle HTTP traffic. HTTP.sys has system wide settings to handle various restrictions around URL. You might be hitting one of them.
See the following article to find out those settings:
http://support.microsoft.com/kb/820129
You will need to restart http service and your WCF service. If it is hosted in IIS, restart IIS. UrlSegmentMaxLength seems to be an interesting for your URI template.