WCF

Book “SOA Patterns with BizTalk Server 2009” by Richard Seroter, review

Leonid Ganeline — Wed, 29 Jul 2009 01:10:57 GMT

Book “SOA Patterns with BizTalk Server 2009” by Richard Seroter, review

Here is a page from publisher ([PACKT] Publishing) http://www.packtpub.com/soa-patterns-with-biztalk-server-2009/book

Questions:

Who is the reader of this book? What is the knowledge and experience level of the reader? How good is the book structure?

I think the reader should be a seasoned BizTalk developer. It is not for an entry level developer.

This book is for architects, but for architects with wealthy knowledge of the BizTalk. I would suggest it for a senior BizTalk developers, which is equal to an Integration Architect title.

You can read the first three and the last four chapters of this book only for a quick review of your knowledge.

I highly recommended the chapters from 4th to 7th. They are from Richards’s wealthy experience. They are the heart and soul of the book. I would like to see much more such interesting things, maybe in next edition of this book?

Is it about BizTalk 2009 or about BizTalk?

Chapters from 9th to 12th are about BizTalk 2009 features and tools. Other chapters are more common and do not depend on the last version. They are more than that, better than that.

Is it about SOA Patterns?

Yes, it is.

Is it the “recipe” book?

The book contains a few good recipes, but indeed it is not a recipe book.

Is it the button-to-button book?

No, luckily it is not.

How is the book covering the topics?

Chapter	Audience	Level (1-5)	Grade (1-5)
Chapter 1: Building BizTalk Server 2009 Applications	Architect Developer	3 1	3 1
Chapter 2: Windows Communication Foundation Primer	Developer	1	1
Chapter 3: Using WCF Services in BizTalk Server 2009	Developer	3	3
Chapter 4: Planning Service-Oriented BizTalk	Architect	3	4
Chapter 5: Schema and Endpoint Patterns	Developer, Architect	3	5
Chapter 6: Asynchronous Communication Patterns	Developer	4	5
Chapter 7: Orchestration Patterns	Developer, Architect	5 3	4 4
Chapter 8: Versioning	Developer	3	3
Chapter 9: New SOA Capabilities in BizTalk Server 2009: WCF SQL Server Adapter	Developer	3	3
Chapter 10: New SOA Capabilities in BizTalk Server 2009: UDDI Services	Developer	3	2
Chapter 11: New SOA Capabilities in BizTalk Server 2009: ESB Guidance 2	Developer	3	3
Chapter 12: What's Next

Where Level:

1 – developers with entry level knowledge of BizTalk and no working experience

2 – developers with entry level knowledge of BizTalk and small working experience

3 – developers with fair level knowledge of BizTalk and fair working experience

4 – developers with expert level knowledge of BizTalk and fair working experience

5 – developers with expert level knowledge of BizTalk and expert working experience

I have to say, that several parts of this book “must be read” by every BizTalk developer. I insist these parts MUST be an essential part of the BizTalk Documentation from the early start and it is a shame of Microsoft these chapters are not included in the BizTalk Documentation. For example, the Schema Patterns, Chapter 5, how could developers work with Web-services without basic knowledge about basic principles of serializing schemas to .NET classes?

Sometimes author jumps from really interesting discussions about patterns to examples of how to implement it in “too much details” fashion.

When I ticked on the chapters with 2 or 1 grade, I thought “I cannot find any reason to include this chapter in the book. Here Richard presents only the general information but nothing from his experience. Geners description and general examples, but I would prefer to know the expert opinions, expert arguments, expert views, expert pros and cons.” I understand why these chapters are in the book. However, I strongly believe that the book worth reading if the author express his/her opinions in the text.

For Chapter 11 about ESB I would suggest to see the webcast by Richard Seroter “A look at the ESB Toolkit 2.0 in BizTalk Server 2009” http://cloudtv.cloudapp.net/ViewWebcast.aspx?webcastid=2521553277324634479. It is kind of the up-to-date version of this Chapter.

Conclusion

Pros:

“SOA Patterns with BizTalk Server 2009” book contains several very interesting topics.

Book contains an expert point of view.

Book also covers several useful SOA patterns implemented in/with BizTalk Server.

The best part of the book is not only about “how” but about “why” as well.

Cons:

Apparently, the author includes some chapters just to pad the book. But the usable volume is still more than a half. This is good proportion. Yes, it is a good proportion. Usually books of this kind have smaller “performance index”.

Conclusion

This book would be very helpful for the Integration Architects and BizTalk Developers.

Author is one of the most respectful BizTalk experts in the world and his point of view is always interesting.

Must have for every BizTalk Developer.

Highly Recommended

BizTalk WCF-BasicHttp adapter issue with http://www.w3.org/2001/XMLSchema namespace

Leonid Ganeline — Tue, 30 Jun 2009 04:31:51 GMT

BizTalk WCF-BasicHttp adapter issue with http://www.w3.org/2001/XMLSchema namespace

I am using the WCF-BasicHttp adapter to consume outer Web-service and getting the error (actually if I have retry>0, I am getting Warning first. See below:

Event Type: Warning
Event Source: BizTalk Server 2006
Event Category: BizTalk Server 2006
Event ID: 5743
Date:  ...
Time:  ...
User:  ...
Computer: ...
Description:
The adapter failed to transmit message going to send port "..." with URL "...". It will be retransmitted after the retry interval specified for this Send Port. Details:"Unable to read the stream produced by the pipeline.
Details: The value 'd:date' is invalid according to its schema type 'http://www.w3.org/2001/XMLSchema:QName' - 'd' is an undeclared namespace. ".
...

or (After retry the previous message the retry limit for this port)

Event Type: Error
Event Source: BizTalk Server 2006
Event Category: BizTalk Server 2006
Event ID: 5754
Date:  ...
Time:  ...
User:  ...
Computer: ...
Description:
A message sent to adapter "FILE" on send port "..." with URI "..." is suspended.
Error details: Unable to read the stream produced by the pipeline.
Details: The value 'd:date' is invalid according to its schema type 'http://www.w3.org/2001/XMLSchema:QName' - 'd' is an undeclared namespace.
MessageId: ...
InstanceID: ...
...

Very srange. When I tried the same Web-service with SoapUi, the result of the verification of the Response message is similar.

line 8: Invalid xsi:type qname: 'd:string' in element ...@http://...

What is wrong with response message?

Response Message:

<e:Envelope xmlns:d="http://www.w3.org/2001/XMLSchema" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns:wn1="..." xmlns:wn2="..." xmlns:wn0="..." xmlns:e="http://schemas.xmlsoap.org/soap/envelope/">
   <e:Body>
      <wn2:ActionResponse>
         <wn2:MyResponse i:type="wn2:MyResponseType">
            <wn2:Detail i:nil="true"/>
            <wn2:MyMsg i:type="wn2:ArrayOfMyMsgType">
               <wn2:MyMsgType i:type="wn2:MyMsgType">
                  <wn2:MsgDescriptionText i:type="d:string">...</wn2:MsgDescriptionText>
                  <wn2:MsgIdentificationID i:type="d:string">...</wn2:MsgIdentificationID>
                  <wn2:MsgSeverityLevelCode i:type="wn2:MsgSeverityLevelType">...</wn2:MsgSeverityLevelCode>
                  <wn2:MsgSourceText i:nil="true"/>
               </wn2:MyMsgType>
            </wn2:MyMsg>
         </wn2:MyResponse>
      </wn2:ActionResponse>
   </e:Body>
</e:Envelope>

Investigation discovered that the issue is in the namespace prefix "d". If I change it to the "xsd", the error disappeared.

Questions:

How to work around this?
Is it the error in the response message?
Is it an error in the WCF-BasicHttp adapter?

How to work around this issue?
I changed the WCF-BasicHttp port for the old SOAP port and SOAP port works fine.

Is it the error in the response message?
I didn't find any limits for the "http://www.w3.org/2001/XMLSchema" namespace and for prefixes for it. The only limit is "don't use the prefixes, started with 'xml' letters". It is the common practice to use "xsd" prefix for the "http://www.w3.org/2001/XMLSchema" namespace. But it is not the rule.
Seems the WCF-BasicHttp adapter is "too smart".

Is it an error in the WCF-BasicHttp adapter?
possible...

Review "MCTS Self-Paced Training Kit (Exam 70-503): Microsoft .NET Framework 3.5 Windows Communication Foundation (PRO-Certification)"

Leonid Ganeline — Wed, 15 Oct 2008 21:58:00 GMT

Review "MCTS Self-Paced Training Kit (Exam 70-503): Microsoft .NET Framework 3.5 Windows Communication Foundation (PRO-Certification)"

http://www.amazon.com/MCTS-Self-Paced-Training-70-503-PRO-Certification/dp/0735625654/ref=sr_1_12?ie=UTF8&s=books&qid=1224042536&sr=8-12

I like this series of books (SPTK - Self-Paced Training Kit) because the short theory here is always ended with real world examples. And these examples shows how the product is used in the real situations, to solve the real problems. It is like the prioritization of the functionality.

In the WCF documentation on the MSDN there is no such prioritization, great list of the features is here and no clue what are the main features and what are the secondary, additional features.

In the SPTK books there are no place to all features, the goals of these books are different. There are only the main features and steps how they are used to get the real result. For example, the part about MessageContract. A lot of information are in the MSDN, but it is realy hard to understand what the purpose of the MessageContract is. The real world example is shown in this book, how to use the MessageContract to transmit the license key to the client. Short example gives us the understanding of this artifact.

I am working with Web-services more then 4 years, and last year mostly with WCF-services. I was using this book to review my knowledge to make it more systematic. I didn't use this book to prepare for exam ( See discussion about the sertification exams here http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=3280207&SiteID=1 )

I use every information source to *understand* what is going on inside the product, why these features were included in the product, what alternatives were and are. Why so? Knowledge does not stucked in my brain without answers to this questions. I could not study the product in the *button-by-button* style as monkey.

I have to know *why*.

Teaching technics usualy use the patterns how the product should not be used, the samples of the improper practice. Usualy it is hard to teach proper technics without list the improper practices. Sometimes one sample of the wrongdoing is worth dozens samples of welldoing.

How does this series of books the SPTK is different from oother books published by Microsoft?

Here are only described the *main* product features. These features were selected by Microsoft itself and it works as a unofficial priotirizing. It is very important.
Here we see the *real world* problems and ways to resolve them with help of the main product features.
In these books are the concisely description (and sometimes the history) what was the *source of these features*.
Here we could see the samples of the *improper practice*, how the product should not be used.

Pros:

This book is the Microsoft vision of what is the intend of the WCF, how the WCF should be used.
The concise information about WCF is concentrated in the *Lessons*. The real world samples are placed near it. These samples are also concentrated on the main things.
I very like the *Lesson Summary* parts. These lists are the lists of the *prime features* of the WCF.

Cons:

Sometimes the book gives us the method in the samples that are obsolete. Say, the generation of the classes from XSD with XSD.exe utility. Several generation of the Software Factory could make this and SvcUtil.exe so.
Sometimes the description are not perfect. I have feeling that authors did not squeeze out the whole information from the BizTalk team :) and this is not surprize me because of the huge WCF feature pool. (For instance, we are asked on page.66 to comment attribute the [XmlSerializerFormat...] and regenerate scheams again, then make sure these schemas are going to get big differences from the default schemas. All these exisises with regenerating are useless without detailed explanations.)

Conclusion:

I know several good sources of the information about WCF for deep studing.

Samples in .NET SDK
The Book "Programming .NET Components", 2nd Edition by Juval Lowy
MSND forums (http://social.msdn.microsoft.com/forums/en-US/wcf/threads/ )

- and this book is good addition to this list.

I mark this book with 5 stars.

It has flaws, but benefits of using it as a fast and reliable source to study WCF are great.

Best regards!

WCF: performance counter names

Leonid Ganeline — Tue, 14 Oct 2008 17:04:53 GMT

The WCF has such structure of the performance counter names:

http://msdn.microsoft.com/en-us/library/ms735098.aspx

ServiceName@ServiceBaseAddress
(ServiceName).(ContractName)@(endpoint listener address)
(ServiceName).(ContractName).(OperationName)@(first endpoint listener address)

In MSDN we have:
"There is a limit on the length of a performance counter instance's name. When a Windows Communication Foundation (WCF) counter instance name exceeds the maximum length, WCF replaces a portion of the instance name with a hash value." http://msdn.microsoft.com/en-us/library/ms731052.aspx

In my case WCF has generated the names:

notif28.inoti60.removebyrefer54@82rapper|notificationwrapper.svc
notif28.inoti60.removebymsgid@82rapper|notificationwrapper.svc
notif28.inoti60.removebyemailid@82rapper|notificationwrapper.svc
notif28.inoti60.schedule@82rapper|notificationwrapper.svc

(Sorry for rapper :) Originally it was Wrapper)

The question is:

Can I use these names as hard-coded names or
next time the WCF could generate different names???

BTW Such names with a hash value are disaster if I need to use the performance counters in my code.

Say I'd like to get counters for the operation with name "RemoveByReferenceMessage" name.
How I can find my counters with code if I have names:
notif28.inoti60.removebyrefer54@82rapper|notificationwrapper.svc
notif28.inoti60.removebymsgid@82rapper|notificationwrapper.svc
notif28.inoti60.removebyemailid@82rapper|notificationwrapper.svc
notif28.inoti60.schedule@82rapper|notificationwrapper.svc

???
How many chars of the operation name I have to use for search?
How many chars of the endpoint name I have to use for search?
How many chars of the service name I have to use for search?

One good part of this is that is the hash algorithm always gives us the same names. Al last in my experience.

Now I know only one method to use WCF performance counter names in the custom code:

Start WCF service and get the generated performance counter names from the PerfMon.
Use these names in the code.

Disadvantages: After any change in the ServiceName, ContractName, OperationName, ServiceBaseAddress, EndpointListenerAddress we have to repeat these steps again.

The full discussion is on http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=2810105&SiteID=1

WCF: A utility to change all URLs in .config files by one click

Leonid Ganeline — Wed, 08 Oct 2008 23:07:31 GMT

Hello,

Before Dublin is in charge, especially the Repository for the Web-services I'm using the custom code to manage the buzz with many URLs in Web.config files

There is a utility to change all URLs in .config files by one click.

http://www.codeplex.com/FilesModificatorAdmi

1. Purpose.
In my current project we've got a lot of composite WCF-services. We have several environments: Development,Test1, Test2, Production.
We don't have the service repository. That means when we move the services from one environment to another, we have to change addresses (URLs) in the <client> sections of all Web.config files (several dozens). Boring and error prone work, isn't it?

The FilesModificatorAdmin utility was created to change all addresses in all Web.config files by one click.

2. How it works.
We define the files that should be scanned and changed. We define the root folder for search. We define the replacements substrings like "http://Env1.MyCompany.com/Composite/Promo/PromoService.svc". The utility derives the searching substring RegExes from the replacement substrings like ""http[^\"]*?PromoService.svc".

Then the FilesModificatorAdmin utility scans all defined files in all folder tree and replace the substrings.
Utility creates the copy of the changed files as OldName.copy.
Utility output the progress to the screen and optionally to the log file.
Utility could optionally just scan the files and show how many searching substrings were found and where.

3. Notes.
* The rules to derive the RegEx for the search are hard coded.
* If the FilesModificatorAdmin found the searching substrings but the string does not changed (it is possible because the searching sub string RegEx could find the substring that is equal the replacement substring) the FilesModificatorAdmin does not change the substring. In this case it shows that sub strings were found if option the "find only and do not replace the Substrings" is checked, and it shows that substrings were not found if option the "find only and do not replace the Substrings" is unchecked.

WCF: Main Types: Outline

Leonid Ganeline — Tue, 24 Jun 2008 22:01:28 GMT

Notes

· Bindings are spread across several namespaces.

· DataContractAttribute is placed in the System.Runtime.Serialization namespace not in the System.ServiceModel namespace.

· Configuration sections are spread across several namespaces.

· ClientSection and ServicesSection: First has the structure client/endpoint, the second – services/service/endpoint. Asymmetric.

System.ServiceModel.dll

System.ServiceModel

· ServiceHost

· ChannelFactory<TChannel>

· ClientBase<TChannel>

Contracts:

· ServiceContractAttribute

· OperationContractAttribute

· MessageContractAttribute

· FaultContractAttribute

Bindings:

· BasicHttpBinding

· NetMsmqBinding

· NetNamedPipeBinding

· NetPeerTcpBinding

· NetTcpBinding

· WS2007FederationHttpBinding

· WS2007HttpBinding

· WSDualHttpBinding

· WSFederationHttpBinding

· WSHttpBinding

Exceptions:

· CommunicationException

· …

System.ServiceModel.Activation

· ServiceHostFactory

· WorkflowServiceHostFactory

System.ServiceModel.Activation.Configuration

· DiagnosticSection

System.ServiceModel.Channels

Interfaces:

· IChannel

· IChannelFactory<TChannel>

· IChannelListener<TChannel>

Abstract classes:

· Binding

· BindingContext

· BindingElement

· ChannelFactoryBase<TChannel>

· ChannelListenerBase<TChannel>

· CommunicationObject

· Message

· MessageHeader

· …

Bindings:

· CustomBinding

Binding Elements:

· TransportBindingElement

· MessageEncodingBindingElement

· …

System.ServiceModel.Configuration

Sections:

· BehaviorsSection

· BindingsSection

· ClientSection

· DiagnosticSection

· ServicesSection

Element: System.Configuration.ConfigurationElement

· BaseAddressElement

· …

ElementCollection: System.ServiceModel.Configuration.ServiceModelEnhancedConfigurationElementCollection<ComMethodElement>

· BaseAddressElementCollection

· …

System.ServiceModel.Description

· ServiceEndpoint

Behavior interfaces:

· IContractBehavior

· IEndpointBehavior

· IOperationBehavior

· IServiceBehavior

Descriptions:

· ContractDescription

· FaultDescription

· ServiceDescription

System.ServiceModel.Dispatcher

· ChannelDispatcher

* ClientOperation

* ClientRuntime

· EndpointDispatcher

Filters:

· ActionMessageFilter

· MatchAllMessageFilter

· MessageFilter

· …

System.ServiceModel.MsmqIntegration

· MsmqIntegrationBinding

System.ServiceModel.Security

Credentials:

Encoders:

System.ServiceModel.Security.Tokens

Tokens:

SecurityTokenParameters:

System.Runtime.Serialization.dll

System.Runtime.Serialization

Attributes:

· CollectionDataContractAttribute

· DataContractAttribute

· DataMemberAttribute

· EnumMemberAttribute

System.WorkflowServices.dll (v3.5)

System.ServiceModel

· WorkflowServiceHost

Bindings:

· BasicHttpContextBinding

· NetTcpContextBinding

· WSHttpContextBinding

WCF: Set up environment to use Transport level security (SSL)

Leonid Ganeline — Thu, 19 Jun 2008 18:25:57 GMT

We should install the certificate to the server that hosts the services with Transport level security.

For tests we could use the self-made certificate, for production we recommend to use the certificate issued by the industrial certificate provider as the VeriSign.

1. Install Microsoft .NET Framework 2.0 Software Development Kit (SDK) (x64) [http://www.microsoft.com/downloads/details.aspx?familyid=1AEF6FCE-6E06-4B66-AFE4-9AAD3C835D3D&displaylang=en]. It is installed by default to the "C:\Program Files\Microsoft.NET\SDK\v2.0 64bit\Bin " folder.

2. [Optionally, only if you also have server certificate and want to refresh it]"C:\Program Files\Microsoft.NET\SDK\v2.0 64bit\Bin\certmgr.exe" -del -r LocalMachine -s My -c -n MyCompany-HTTPS-Server

3. "C:\Program Files\Microsoft.NET\SDK\v2.0 64bit\Bin\makecert.exe" -sr LocalMachine -ss My -n CN= MyCompany-HTTPS-Server -sky exchange -sk MyCompany-HTTPS-Key

4. Install the new certificate to the IIS by the Web Server Certificate Wizard. Open IIS Admin, choose the Web-site, Properties, Directory Security tab, Secure communication – Server Certificate… button, it starts the Web Server Certificate Wizard .

5. Check if the IIS / Web Site / Properties / tab Web Site - SSL Port set up to 443 (

To expose the service metadata by HTTPS and HTTP use:

To expose the service metadata by HTTPS or HTTP only, change attribute the httpsGetEnabled or httpGetEnabled to false.

[1] Wikipedia - http://en.wikipedia.org/wiki/Secure_Sockets_Layer

[2] Transport Security Overview - http://msdn.microsoft.com/en-us/library/ms729700.aspx

[3] Working with Certificates - http://msdn.microsoft.com/en-us/library/ms731899.aspx

WCF: Data contract names: don't use names with "Response" and "Request" suffixes!

Leonid Ganeline — Mon, 02 Jun 2008 22:43:51 GMT

After creating simple WCF service I've got strange errors (see below).

The issue was in the names of the response messages.

I used the simple custom rule to name request and response messages (.NET DataContract classes):

<OperationName>Request and <OperationName>Response

For instance I created GetTokenResponse class for the response message of the GetToken operation.

And this is the wrong rule!

Why? Because the WCF creates these names for the WSDL metadata files:

For instance I've got:

...

<wsdl:message name="ITokenStore_GetToken_OutputMessage">

<wsdl:part name="parameters" element="tns:GetTokenResponse" /> ...

....<wsdl:operation name="GetToken">

<wsdl:input wsaw:Action=http://MyServices/TokenStore/2008-05-29/ITokenStore/GetToken message="tns:ITokenStore_GetToken_InputMessage" />

<wsdl:output wsaw:Action=http://MyServices/TokenStore/2008-05-29/ITokenStore/GetTokenResponse message="tns:ITokenStore_GetToken_OutputMessage" />

When I changed the name to the GetToken_Response the errors disappeared.

It is not an error in the WCF it is just undocumented feature.

The problem is the error text gives us unhelpful and ambiguous information.

See the article in MSDN: http://msdn.microsoft.com/en-us/library/ms731045.aspx
Not a clue about these rules.

Conclusion:

Don't use the messages names with suffixes Response, Solicit, Request.

Don't use the name convention for the request and response messages (.NET classes) like <OperationName>Request and <OperationName>Response !

ADDITION [2009-07-26]: This behavior is because of the WSDL standard.

See http://www.w3.org/TR/wsdl

2.4.5 Names of Elements within an Operation

The name attribute of the input and output elements provides a unique name among all input and output elements within the enclosing port type.

In order to avoid having to name each input and output element within an operation, WSDL provides some default values based on the operation name. If the name attribute is not specified on a one-way or notification message, it defaults to the name of the operation. If the name attribute is not specified on the input or output messages of a request-response or solicit-response operation, the name defaults to the name of the operation with "Request"/"Solicit" or "Response" appended, respectively.

Error in SoapUI

, when we've tried to get the metadata:

... ERROR:javax.wsdl.WSDLException: WSDLException (at /HTML): faultCode=INVALID_WSDL: Expected element '{http://schemas.xmlsoap.org/wsdl/}definitions'.

Error in IE: by address the <ServiceAddressURL>

The service encountered an error.

An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is:
System.InvalidOperationException: An exception was thrown in a call to a WSDL export extension: System.ServiceModel.Description.DataContractSerializerOperationBehavior
 contract: http://MyServices/TokenStore/2008-05-29:ITokenStore ----> System.Xml.Schema.XmlSchemaException: The global element 'http://MyServices/TokenStore/2008-05-29:GetTokenResponse' has already been declared.
   at System.Xml.Schema.XmlSchemaSet.InternalValidationCallback(Object sender, ValidationEventArgs e)
   at System.Xml.Schema.BaseProcessor.AddToTable(XmlSchemaObjectTable table, XmlQualifiedName qname, XmlSchemaObject item)
   at System.Xml.Schema.Preprocessor.Preprocess(XmlSchema schema, String targetNamespace, ArrayList imports)
   at System.Xml.Schema.Preprocessor.Execute(XmlSchema schema, String targetNamespace, Boolean loadExternals)
   at System.Xml.Schema.XmlSchemaSet.PreprocessSchema(XmlSchema& schema, String targetNamespace)
   at System.Xml.Schema.XmlSchemaSet.Reprocess(XmlSchema schema)
   at System.ServiceModel.Description.MessageContractExporter.Compile()
   at System.ServiceModel.Description.DataContractSerializerMessageContractExporter.Compile()
   at System.ServiceModel.Description.MessageContractExporter.ExportMessage(Int32 messageIndex, Object state)
   at System.ServiceModel.Description.MessageContractExporter.ExportMessageContract()
   at System.ServiceModel.Description.WsdlExporter.CallExtension(WsdlContractConversionContext contractContext, IWsdlExportExtension extension)
   --- End of inner ExceptionDetail stack trace ---
   at System.ServiceModel.Description.ServiceMetadataBehavior.MetadataExtensionInitializer.GenerateMetadata()
   at System.ServiceModel.Description.ServiceMetadataExtension.EnsureInitialized()
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.InitializationData.InitializeFrom(ServiceMetadataExtension extension)
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.GetInitData()
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.TryHandleDocumentationRequest(Message httpGetRequest, String[] queries, Message& replyMessage)
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.ProcessHttpRequest(Message httpGetRequest)
   at SyncInvokeGet(Object , Object[] , Object[] )
   at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)
   at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)

Error in IE: by address the <ServiceAddressURL>?wsdl

The service encountered an error.

An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is:
System.InvalidOperationException: An exception was thrown in a call to a WSDL export extension: System.ServiceModel.Description.DataContractSerializerOperationBehavior
 contract: http://MyServices/TokenStore/2008-05-29:ITokenStore ----> System.Xml.Schema.XmlSchemaException: The global element 'http://MyServices/TokenStore/2008-05-29:GetTokenResponse' has already been declared.
   at System.Xml.Schema.XmlSchemaSet.InternalValidationCallback(Object sender, ValidationEventArgs e)
   at System.Xml.Schema.BaseProcessor.AddToTable(XmlSchemaObjectTable table, XmlQualifiedName qname, XmlSchemaObject item)
   at System.Xml.Schema.Preprocessor.Preprocess(XmlSchema schema, String targetNamespace, ArrayList imports)
   at System.Xml.Schema.Preprocessor.Execute(XmlSchema schema, String targetNamespace, Boolean loadExternals)
   at System.Xml.Schema.XmlSchemaSet.PreprocessSchema(XmlSchema& schema, String targetNamespace)
   at System.Xml.Schema.XmlSchemaSet.Reprocess(XmlSchema schema)
   at System.ServiceModel.Description.MessageContractExporter.Compile()
   at System.ServiceModel.Description.DataContractSerializerMessageContractExporter.Compile()
   at System.ServiceModel.Description.MessageContractExporter.ExportMessage(Int32 messageIndex, Object state)
   at System.ServiceModel.Description.MessageContractExporter.ExportMessageContract()
   at System.ServiceModel.Description.WsdlExporter.CallExtension(WsdlContractConversionContext contractContext, IWsdlExportExtension extension)
   --- End of inner ExceptionDetail stack trace ---
   at System.ServiceModel.Description.ServiceMetadataBehavior.MetadataExtensionInitializer.GenerateMetadata()
   at System.ServiceModel.Description.ServiceMetadataExtension.EnsureInitialized()
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.InitializationData.InitializeFrom(ServiceMetadataExtension extension)
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.GetInitData()
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.TryHandleMetadataRequest(Message httpGetRequest, String[] queries, Message& replyMessage)
   at System.ServiceModel.Description.ServiceMetadataExtension.HttpGetImpl.ProcessHttpRequest(Message httpGetRequest)
   at SyncInvokeGet(Object , Object[] , Object[] )
   at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)
   at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)

WCF: Technique of debugging inconsistency between Wsdl and Response messages.

Leonid Ganeline — Tue, 13 May 2008 23:36:15 GMT

WCF: Technique of debugging inconsistency between Wsdl and Response messages.

I was working with several web-services as a client and had several issues the same kind. WSDL of this services does not conform the Response messages (See below. I’ve bolded the text related to the issue.). I fixed this issue by changing proxy code. It is not a big issue but now we have to manually change proxy every time we have updated the proxy of this service.

Here the checklist how debugging this case:

[The proxy for the web-service could be created with any method in Visual Studio 2008 as “Add Service Reference”.]

1. We have found that the client code cannot get all data from the service. Some data are lost.

2. Using SoapUI make sure the Response returns all data. This is the sign of this inconsistency!

3. Using debugger we have found that the data are lost exactly in
response = client.Method(request)
line in the client code.

What does it mean? The data are successfully returned in the Response message. But the client proxy code could not process them. When the proxy code is deserializing the response message some data are lost. SoapUI does not process returned data, it just shows them as raw text. The proxy code is trying to deserialize this text, converting text to objects in memory. [The deserializer is the code in the Microsoft libraries in the System.Runtime.Serialization namespace. There are two of them in WCF: XmlSerializer and DataContractSerializer.] Some of returned data magically disappeared in the Deserializing process. Description of these cases is in article “WCF: values disappeared in response: derived classes and serialization/deserialization order error” [http://geekswithblogs.net/LeonidGaneline/archive/2008/05/01/wcf-values-disappeared-in-response-derived-classes-and-serializationdeseriazlization-order.aspx]

4. Go to the proxy source code (maybe in Refeference.cs file) and fix code (see below). This make proxy inconsistent with Wsdl file and next time when you update this Web or Service reference you have to fix proxy code again. But the client deserializes the Response messages properly now!

5. Document this fix! And do not make it in proxy code. J

You lucky if you have got inconsistency in Response messages. The worst situation if inconsistency is in Request messages. There are only two options: the service does not care about these inconsistencies and you are lucky again, or service reject your request with fault message. Moreover I make sure this message does not give you a clue what is going on. Try to get the “correct” request from any source and follow the same debugging technique with it.

[WSDL ]

<xsd:complexType name="ArrayOf_xsd_string">

<xsd:sequence>

<xsd:element minOccurs="0" maxOccurs="unbounded" name="item" type="xsd:string" />

</xsd:sequence>

</xsd:complexType>

…

<xsd:complexType name="PromoDetails">

<xsd:sequence>

…

<xsd:element name="assetTypes" nillable="true" type="impl:ArrayOf_xsd_string" />

…

</xsd:sequence>

…

[Response message]

…

<assetTypes>Album</ assetTypes >

</assetTypes>

…

[Response message How it should be with regard to WSDL]

…

<item>Album</ item >

</assetTypes>

…

[Auto generated Proxy code]

…

private string[] assetTypesField;

[System.Xml.Serialization.XmlArrayAttribute(IsNullable=true, Order=1)]

[System.Xml.Serialization.XmlArrayItemAttribute("item", IsNullable = false)]

public string[] assetTypes {

get {

return this.assetTypesField;

}

set {

this.assetTypesField = value;

this.RaisePropertyChanged("assetTypes");

}

…

[Fixed Proxy code]

…

private string[] assetTypesField;

[System.Xml.Serialization.XmlArrayAttribute(IsNullable=true, Order=1)]

[System.Xml.Serialization.XmlArrayItemAttribute("assetTypes ", IsNullable = false)]

public string[] assetTypes {

get {

return this.assetTypesField;

}

set {

this.assetTypesField = value;

this.RaisePropertyChanged("assetTypes");

}

…

WCF: Availability of the WCF services

Leonid Ganeline — Wed, 07 May 2008 18:48:18 GMT

The requirements look easy:
We need to monitor the health of the WCF services, availability of the WCF services. Are they up or down?
But we don't want to call operations of the service because it sometime could change the service internal status and these changes are out of our control.
Some services have special Heartbeat() operation to make the health monitoring easily, but the most have not.
We don't have to check the work status of the web-method. That means we don't care if some underlying services, like SQL databases, don't work and the services available but response with errors. We just want to know are web-services up or down, could they response at all or not. It should be something really easy.

Let's start:
I thought this is quite routine task to the service consumers and there should be several routine decisions.
As I know the OpsMngr2007 use something simple to measure the web-service health.

I've asked gurus on the MSDN forums about this.

Dan Rigsby proposed:
"A one way Ping() method on the server works well. If there is an exception, then the channel is broken. You can have a timer run Ping against the server at some interval.
If this is a duplex callback system you need to be careful. The server might also need to check if the client is still alive. You cant have both the servicecontract and callbackcontract have the same named methods, so you will have to rename one of them."

Thanks, Dan!

I've tried to
      >ping http://text.company.com/adfadfad/asdfadf/adfadfadf.asmx
and
     >ping http://text.company.com/adfadfad/asdfadf/adfadfadf.asmx?wsdl

The ping works only for the host name, like
      >ping text.company.com
not for web-service URL

It is not what I want.

It checks the health of the host, not the web-service.
It does not cover cases with several services on the one host.
It does not cover cases when the host is OK but the service is not response.

Islam Eldemery proposed:
"try to subscribe to the events of the communication object (in the client side), so if a service stopped or disconnected you may handle the fault event.. (remember that it can only fault once).

proxy.InnerChannel.Faulted += new EventHandler(InnerChannel_Faulted);

or
proxy.InnerDuplexChannel.Faulted += new EventHandler(InnerDuplexChannel_Faulted);

see my example of handling a service in a chat application
http://www.codeproject.com/KB/IP/WCFWPFChatRoot.aspx
if this is a duplex communication, to handle the service on the service side, try to check every time on each callback object you have, to see if someone has been aborted or not before you using it (may be a client disconnect for a network failure.. etc.)"

Islam, thanks for response!

Unfortunately with this technique we can intercept only errors after we unsuccessfully call the service operation, right?
It is not our case. We want to check the availability not "post mortem" but proactively. For instance, click a button and get health of all services. And we cannot call the service operations, it's one of requirements.

Martin16 proposed:
"...
Additional ideas (for IIS/HTTP WCF Services) are
1) a custom availability operation in your service which checks all resources and gives back a result your web application monitor can parse.
2) enable WCF performance counter and create a monitor on top of that.
3) buy Avicode MP (should provide native WCF Service support)"

Thanks for help, Martin16!

Yeah, 1) is the Heartbeat() operation. It doesn't work in my case where the services are out of mu control.
For 2) First, we want actively to request the health status not to listen how the service responses to the requests of the other clients.
Second, the WCF performance counters... OK I use them with OpsMng2007 I don't like them very-very much. (It's another story).
3) The third-part utils should use the same APIs we use, not something secret. I also use OpsMngr2007. But I want to use simple and absolutely open (to me) source code.

...
So far so good.
Is it possible to use Mex endpoint or something like HttpRequest to <URL>?wsdl to make sure the service is up?

I've got one method from the book "Programming WCF Services" by Juval Lowy (page 71).
Code Snippet:

   MetadataExchangeClient mexClient =
bool isServiceUp = true;
try
{
   string address = "http://localhost/MyService.svc?wsdl";new MetadataExchangeClient(new Uri(address), MetadataExchangeClientMode.HttpGet);
   MetadataSet metadata = mexClient.GetMetadata();
// if service down I get the exception
}
   catch (Exception ex)
{
    isServiceUp = false;
}

I catch the Exception like {"Metadata contains a reference that cannot be resolved: "http://localhost/MyService.svc?wsdl"} System.Exception {System.InvalidOperationException}

Easy and don't heavy load the service.

P.S. Please, make sure you've read good comment by Islam Eldemery below.

================================================================

Additions:

[2009-07-14]

I moved here a text from the discussions below:

Finally, I was creating the custom solution with Heartbeat().
Of course only some Web-services has this method, then I used the regular methods in specific fashion.
1. I must use the method that doesn't change the inner state of the service (logging is OK).
2. I didn't want to overload the service.

I used the insider information about these services.
The idea is to get the ERROR response. I just want response. And the error is a good solution. It doesn't change the service status, it does not overload the service.

The bad thing with the error response is it strictly depends of the implementation. Than means it work only if you know enough about insides of the service.
Other bad thing is you have to implement the pseudo-Heartbeat() in specific way for different services. It consumes the development time.

Conclusion (up-to-date):

Creating a service with high availability, create a Heartbeat() method to provide clients with instrumentation to check the availability of this service. BTW This method could return a valuable information about current/max performance, payload, etc.

========================================================================================