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WCF Service Error

I was modifying a service last night and I got this error when I hit one of the two endpoints of the service.
The server was unable to process the request due to an internal error...
For search engines (and anyone having a hard time reading the image), it says:

The server was unable to process the request due to an internal error. For more information about the error, either turn on IncludeExceptionDetailInFaults (either from ServiceBehaviorAttribute or from the configuration behavior) on the server in order to send the exception information back to the client, or turn on tracing as per the Microsoft .NET Framework 3.0 SDK documentation and inspect the server trace logs

The other endpoint on my service was unaffected. Usually when I do something stupid, I get the “Yellow Screen of Death” the first time I try to reach my service due to an improper web.config or some other easily correctable thing. This was the first time that I had seen this.

I did some Googling and found out specifically how to get the “real” error message. I had to change my serviceDebug tag in my service’s web.config (located in system.ServiceModel/behaviors)

This gave me a much more helpful message telling me that one of the elements in one of my request objects had already been defined (name and type were the defining factors) in another existing request.

There were two fixes for this. Once was a “hack” in my opinion and the other was the “correct” solution. The hack was to turn off metadata exchange on that endpoint (my particular error was related to generating the WSDL). To do that, I would have set the

to

and remove this line from beside my endpoint definition.

That would prevent developers from inside the company from generating proxy classes automatically with svcutil.exe. I didn’t want that at all.

What I did instead was to rename the element to something that made more sense anyway. This time when I built, the endpoint came up with no problem and the link to the WSDL returned the proper XML that developers would need to “reproxy”. Problem solved and lesson of the includeExceptionDetailInFaults learned!

Web Services Software Factory (5 of 5)

Note: All links current as of the time of this blog post

We have landed. This is tutorial part 5 of 5. In parts 1-4 (part 1 starts here) we created a web service that does some simple encryption, decryption, and hashing. Before beginning this part of the tutorial, please create a virtual directory in IIS pointing to the Web Service project that you set up in part 4 and make it a .Net application. I named the virtual directory CryptService and as such I can browse to http://localhost/CryptService/CryptService.svc and see the service.

Create a new C# Console Application. I named my application TestCryptService. Right click on your project in solution explorer and select “Add Service Reference”. Put your URL to your service in and click Go. After a few moments, you should see what was discovered about your service. Change the namespace to CryptService and click Ok.
Add Service Reference to Project

Notice that all of the binding information has been added to your app.config. If you look at the endpoint section, you will see that /basic was added to the end of the CryptService.svc. I mentioned last time that that allows you to create multiple endpoints to the same point, and just use different bindings, etc.

Now, within the Program.cs file that was created for you, enter in this code:

When I run this code, I see this output:
Test Console Output

That is IT! If you’ve made it this far and see that output, you are done. You are now ready to use the Web Services Software Factory to make web services yourself. As always, if you didn’t get these results, double check your steps and if you are still having problems, leave me a comment and I will try to help you.

All code was written as throwaway code, so I realize that it could use some refactoring and some optimization. The point of this tutorial was to expose you to using the WSSF in more than a “Hello World” kind of way and to at least mimic the real world with something a little bit fun.

Web Services Software Factory (4 of 5)

Note: All links current as of the time of this blog post

We are in the home stretch. If you haven’t already, you may want to take a look at tutorial parts 1, 2, and 3 before beginning this one.

At this point, we’ve defined our service, created Data Contracts and Service Contracts, implemented the serivce, and programmed the code behind the endpoints. All we have left to do before this service is fully functional is to create the Host Contracts, which will set up the actual endpoints for us.

In your Solution Explorer, right click on the MyCryptographyService.model and choose Add –> New Model. In the dialog, select Host Model and complete the the form and click finish.
New Host Contract Model Dialog

This brings up a new designer surface for the Host Designer.
Host Model Designer

The very first thing we need to do is to right click on the Host Model in the Host Explorer and select “Add New Host Application”.
Add New Host Application Menu

This will create HostApplication1. Right click on it and view properties. Change the name to “CryptographyServiceWS” and the Implementation Technology to “WCF Extensions”. For Implementation Project you need to pick the project that is going to be the one the people will actually connect to. You can create your own Web Services project if you’d like, but there is one already included for us, so I will use that one for the purposes of this experience. Expand the dropdown as shown below and choose MyCrytographyService.Host.
Choose a Host Project

Return to the Host Explorer, right click on CryptographyServiceWS and choose “Add New Service Reference”. This creates ServiceReference1.
Add Service Reference to Host

Right click on ServiceReference1, choose properties and set its name to CryptService. Select to Enable Metadata Publishing to true. For Service Implementation Type, click the ellipses to bring up this dialog and choose CryptService.
DSL Model Element Selector

Go back to the Host Explorer. Right click on CryptService and choose “Add New Endpoint”. Endpont1 will appear. Right click on Endpoint1, select properties and change its name to Crypt, leave Binding Type at basicHttpBinding, and enter “Basic” in the Address field. As the tooltip says, the Address field allows you to append something to the name of the endpoint so that you can create many different endpoints, each to the same code. The point being to allow users to connect with many different bindings, but to do that you must create an endpoint for each. Rather than have many different endpoint names, you can just add a suffix. Additionally, this can also be used to version the endpoints on your service.

That’s it. When you click again on CryptService in the Host Explorer, you see this screen on the left. Click “Generate Service” and if you’ve done everything correctly, you should be set to go. If you do not see this screen, that means you have left out a step. Please review the tutorial up to this point and if you are still stuck, leave me a comment and I will try to help.
Auto Generate Service

Now, if you go back to your Solution Explorer and navigate to the Tests folder and look inside the MyCryptographyService.Hosts project, you will see the CryptService.svc file.
CryptService.svc

This is the “page” that people will connect to. In fact, if you right click on it and choose “View in Browser” you should see the page below.
CryptService Page in Browser

If you click the link that is provided on that page, you can see the WSDL from the service itself.
CryptService WSDL

That’s it. Your WCF service is now fully functional. In the final piece of the tutorial, we’ll make a C# Console Application that calls our service and gives us back some results.

Web Services Software Factory (3 of 5)

If you missed the beginning of the series, you should check out Part 1 and Part 2 before beginning this part if you want to follow along.

Today’s tutorial will create the service contracts for our WCF service and actually implement the methods (read: write some code that does something).

First, in your Solution Explorer, right click on MyCryptographyService.model and Add–>New Model.
Right Click Add New Model.

You will need to fill out the form like you see below.
Create New Service Contract Model

If you don’t already have your property window handy, right click in the white designer surface and click properties. Just like with our Data Contracts, select our Project Mapping Table and choose WCF Extension from the “Implementation Technology” dropdown. Set the “Serializer Type” to DataContractSerializer.
Service Contract Model Properties

Since you should be familiar with how the designer surface works (from part 2 of the tutorial), I’m going to move through this part a little more quickly. The toolbox is context sensitive and now displays tools relevant to Service Contracts.
Service Contract Toolbox Context

Drag a Service (name: CryptService), a Service Contract (name: CryptService), an Operation (name: EncryptString), and two messages (EncryptStringRequest and EncryptStringResponse) out onto the designer surface. Arrange and them as shown below.
EncryptString Model

Use the connector tool to connect the objects. Drag a connection between the Service Contract and the Service. Drag another connection between the Operation and the Service Contract. This part is a little bit tricky. You need to associate the “Request” and “Reponse” messages to the operation. However, up to this point, which direction you connected the object did not matter. For the messages, it does. Start on the “Request” message and drag to the Operation. Then for the other connection, start on the Operation and drag it to the “Response” message. You have now finished modeling this Operation.
EncryptString Model Complete

You should drag 2 more Operations onto the surface and call them DecryptString and HashString. Drag 4 more Messages onto the surface and call them DecryptStringRequest, DecryptStringResponse, HashStringRequest, and HashStringResponse. Connect them up like you did for the EncryptString (attaching the Operations to the Service Contract).
Service Model Sans Payload

Now you are almost done. You need need to load up the messages with their payloads. Right click on EncryptStringRequest and Add–>Data Contract Message Part. Name it EncryptionObject. While it is highlighted, examine the Properties Panel. Next to Type, click the Elipses (…) to bring up this dialog box. Choose EncryptionObject from the box and click OK.
Add Encryption Object to EncryptStringRequest
Add EncryptionObject Type

You should also add an EncryptionObject to DecryptStringRequest and a HashObject to HashStringRequest. Add Primitive Message Parts to each of the three responses and call each one “ReturnValue”. (I realize I haven’t come with the most “enterprisey” names during this tutorial… I’m sorry).
Completed Service Contract Model

Now, right click somewhere in the white of the Visual Designer and choose Validate All. If that comes back with errors, recheck your work. If it comes back clean, right click again and choose Generate Code. You will then have additional generated code appear in MyCryptographyService.ServiceImplementation and MyCryptographyService.ServiceContracts.

Next, right click on the MyCryptographyService.BusinessLogic project and choose to add a new class. Call it CryptographyServiceBusinessLogic. To save some time (and since this code isn’t the point of the tutorial), I’ve included the code here for you.

Next, right click on the MyCryptographyService.DataAccess project and add a new class called CryptographyServiceManager. The code for it is below.

Lastly, we only need to do one more thing before this step of the tutorial is complete. We need to implement the methods that tie into what will be our endpoints. When we defined our service contracts, we defined some methods. We need to write the implementation of those methods that tie them to our business layer (and ultimately to our data access layer).

However, since the generated code can and will change every time we make any changes to the service contract designer, we have to create another code file and create a partial class with the same name as the generated one. Inside, we will override the methods, write our own implementation, assign values to the response, and return it. Create a class in the MyCryptographyService.ServiceImplementation project called CryptImplementation.cs. Then you should have the following code inside.

Notice that this is the class that also uses the translators that you wrote. They allow the class that is the DataContract to be mapped to the class that is the BusinessEntity. The code here should be pretty straightforward, but if you have any questions, please leave them in the comments and I will respond as quickly as possible.

Part 4 should be coming shortly. Until then.

Web Services Software Factory (2 of 5)

If you have missed part one of this tutorial, you can find it here. You will need to have completed the first part of the tutorial in order to complete this one. In this part you will create the data contracts for this service, the business entities, and the translators to go between them. Just like with classic web services, your data contracts and business entities are essentially different objects as far as .Net is concerned, so you have to create something to map their properties to one another. To get started, you need to have the project loaded up.

Right click on the MyCryptographyService.model project and select Add –> New Model
Add a new Data Contract Model

Opt to create a new “Data Contract Model”. Fill in the Mode name as CryptographyService.DataContracts and the XML Namespace as http://peteonsoftware.com (or whatever you’d like).
Add a new Data Contract Model

You should now have a blank visual designer canvas. Click on the canvas and then view your Properties window (you can’t right click and get properties). Click in the “Implementation Technology” property and choose “WCF Extension”.
Choosing an Implementation Technology

You also need to choose the Project Mapping table for the contracts. This is the XML document (found by default in ProjectMapping.xml) that tells the WSSF which role each project will play and where to auto generate the code. This file can be edited and changes are not overwritten. Set the Project Mapping Table property to MyCryptographyService.
Set the Project Mapping Table

Your toolbox will give you context sensitive tools depending on what part of the project that you are working on. While building data contracts, you will see the tools shown below. A Data Contract represents your serializable objects. The Data Contract Enumeration represents your serializable enumerations. Primitive Data Type Collections and Data Contract Collections represent collections of .Net Data Types and your own custom contracts respectively. You can choose what form these collections take, but most often, I could recommend List. Fault Contracts are for representing Exceptions and Aggregation is for representing relationships between objects.
Choosing an Implementation Technology

Next you need to drag a “Data Contract Enumeration” out of your toolbox and onto the visual designer. Click the name on the top (most likely DataContractEnum1) and change its name to HashType. Right click on the contract and choose Add–>Value. Add values of MD5 and SHA256 to the enumeration.
Add a value to a Data Contract Enumeration

Drag another Data Contract Enumeration onto the surface and name it EncryptionAlgorithm. Add two values, called DES and Rijndael to the enumeration. When you are finished, your surface should look something like this.
Completed Data Contract Enumerations

Now, drag a “Data Contract” from the toolbox onto the designer. Change its name to HashObject in the same way that you renamed the enumeration. Right click on the contract and select Add–>Primitive Data Type. Name this property “StringToHash”.
Data Contract Add Primitive Data Type

Let’s now take a look at the properties of this Primitive Data Type that you just added. It has a type of System.String and an order of 0. For any future Primitive Data Types you add, you may need to change the data type here. You also need to set the order here, as well. For now, we can accept the defaults.
Primitive Data Type Properties

Now, select the Aggregation tool from the toolbox and click on the HashType enumeration, hold down your mouse button, and drag the connection over to the HashObject. This will create a new member on the contract. Set its order to 1.
Data Contract Enumeration Properties

Your HashObject and HashType should look like this on the designer.
Completed HashObject and HashType

You should also create an EncryptionObject by dragging another “Data Contract” onto the designer and setting a Text member and an EncryptionType member in the exact same manner as you did with the Hash Object. When you are finished, you should have these four entities on your designer.
Completed Data Contracts

Right click on any area of whitespace on the designer and click “Validate”. You should have no errors. If you do, make sure that you properly followed all of the steps in this tutorial.
Validate Data Contracts

Next, right click on some whitespace again and click “Generate Code”.
Generate Data Contract Code

If you inspect your MyCryptographyService.DataContracts project’s “Generated Code” folder you will find that some classes have been generated for you. Keep in mind that whenever you make changes to your data contracts, you must regenerate the code and these classes will be overwritten. Fortunately, these classes are created as partial classes, so you can make another .cs file and extend these contracts if you really need to.
Generated Data Contracts
Generated Data Contract Source Code

Right click on the project MyCryptographyService.BusinessEntities and choose Add–>Class. Name the .cs file CryptographicEntities.cs. Inside this file, we will define all of our business entities that the data contracts model so that they can be used elsewhere in our solution. Normally, you would define each of these in their own file, or group them in some other way, but for the purposes of this tutorial we will put all of the code in this file. Replace all of the contents of CryptographicEntities.cs (except the using statements) with the following code.

namespace MyCryptographyService.BusinessEntities

{

    public enum EncryptionAlgorithm

    {

        DES = 0,

        Rijndael = 1

    }

 

    public enum HashType

    {

        MD5 = 0,

        SHA256 = 1

    }

 

    public class EncryptionObject

    {

        public string Text { get; set; }

        public EncryptionAlgorithm EncryptionAlgorithm { get; set; }

    }

 

    public class HashObject

    {

        public string StringToHash { get; set; }

        public HashType HashType { get; set; }

    }

}

Now, right click on the MyCryptographyService.ServiceImplemenation project and choose “Create Translator”.
Create Translator

In the First Class to map, choose the DataContracts.EncryptionObject. For the Second Class to map, choose the BusinessEntities.EncryptionObject. Name the mapping class “EncryptionObjectTranslator” and set the namespace to MyCryptographyService.ServiceImplementation.
Translator Mapper Generator

Choose the Text Property in each of the boxes and click map. Then click finish. You can’t map the enumerations from this dialog and will have to edit the code manually. As long as you don’t regenerate this translator, you don’t have to worry about overwriting the manual changes. In fact, I recommend doing this once to get your guidelines and maintaining it manually anyway.
Translator Map Properties

Repeat this process for our HashObjects. Name the translator HashObjectTranslator and only use the wizard to map the StringToHash properties. Next, open up the translators and make the code look like the following: (Note, I aliased the namespaces to make them shorter and easier to work with).
HashObjectTranslator:

using System;

using MyCryptographyService.DataContracts;

using MyCryptographyService.BusinessEntities;

 

using Contract = MyCryptographyService.DataContracts;

using Entity = MyCryptographyService.BusinessEntities;

 

namespace MyCryptographyService.ServiceImplementation

{

    public static class HashObjectTranslator

    {

        public static Contract.HashObject TranslateHashObjectToHashObject(

            Entity.HashObject from)

        {

            Contract.HashObject to =

                new Contract.HashObject();

            to.StringToHash = from.StringToHash;

            to.HashType =

                (Contract.HashType)from.HashType;

            return to;

        }

 

        public static Entity.HashObject TranslateHashObjectToHashObject(

            Contract.HashObject from)

        {

            Entity.HashObject to = new Entity.HashObject();

            to.StringToHash = from.StringToHash;

            to.HashType = (Entity.HashType)from.HashType;

            return to;

        }

    }

}

EncryptionObjectTranslator:

using System;

using MyCryptographyService.DataContracts;

using MyCryptographyService.BusinessEntities;

 

using Contract = MyCryptographyService.DataContracts;

using Entity = MyCryptographyService.BusinessEntities;

 

namespace MyCryptographyService.ServiceImplementation

{

    public static class EncryptionObjectTranslator

    {

        public static Contract.EncryptionObject TranslateEncryptionObjectToEncryptionObject(

            Entity.EncryptionObject from)

        {

            Contract.EncryptionObject to =

                new Contract.EncryptionObject();

            to.Text = from.Text;

            to.EncryptionAlgorithm =

                (Contract.EncryptionAlgorithm)from.EncryptionAlgorithm;

            return to;

        }

 

        public static Entity.EncryptionObject TranslateEncryptionObjectToEncryptionObject(

            Contract.EncryptionObject from)

        {

            Entity.EncryptionObject to =

                new Entity.EncryptionObject();

            to.Text = from.Text;

            to.EncryptionAlgorithm =

                (Entity.EncryptionAlgorithm)from.EncryptionAlgorithm;

            return to;

        }

    }

}

That’s it. You should be able to successfully build your project now and you are now ready for Part 3. If you have any problems, please feel free to leave them in the comments and I will try to get back to you as quickly as I can. Next time, we will create and implement our service contracts. Until then.

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