Here’s two things that caused me a bit of pain when working with WCF. Hopefully these pointers should help you get back to more productive things.

No Output when returning Serialized / Serialised objects.

I had been working on adding a significant number of methods and properties to a series of classes, and when I went to test the service I got literally no output.

Debug points indicated that all properties were there, and valid - but still WCF wasn’t returning anything. There was no exceptions  being returned to the client.

The best tool for debugging these sorts of solutions is to first of all enable Tracing and MessageLogging.  This is done via the WCF Service Configuration Editor, on the Diagnostics tab. 

Once you’ve done that, and re-run the projects - you can open up Service Trace Viewer.  For me under Visual Studio 2008, this was under Microsoft Windows SDK v6.0A > Tools.

This tool then lets you open up the trace log generated in your solution directory, and see all the activity that’s been happening.

From here, it was just a matter of scrolling down to the activity entry that had the yellow hilighting (indicating a warning), selecting it - then clicking on the Errors.

For me, the first time this happened to me, it was because I had stuffed up the DataMember Name values. It has also occurred for other reasons, such as a property not being populated, when I had specified that it was both required, and also that it could not emit a default value.

Can’t get mex to work

No, this isn’t a misguided racial slur. I was having issues setting up the mexHttpBinding on an ASP.NET AJAX WCF Service.

The solutions all point towards the same thing, that you need to set up an endpoint, and set the contract to IMetaDataExchange, then set the behaviour to have <serviceMetadata />. Except that it just wouldn’t let me add that property to my endpoint behaviour, and whenever I changed it to a service behaviour it would then not allow me  to set the other properties I needed for that.

Well, perhaps I’m particularly slow - but hopefully this pointer will help someone else.

1: Create a NEW service behaviour:

<serviceBehaviors>
  <behavior name="MyServiceBehavior">
    <serviceMetadata
      httpGetEnabled="true"/>
    <serviceDebug
     includeExceptionDetailInFaults="true"
     />
  </behavior></serviceBehaviors>

2: Add a new endpoint to your  existing service

<endpoint
   address="mex"
   binding="mexHttpBinding"
   bindingConfiguration=""
   contract="IMetadataExchange" />

3: Add the behaviorConfiguration you added in Step 1 to the Service (NOT the endpoint).

<service
  behaviorConfiguration=”MyServiceBehavior”
  name=”MyProject.MyService”>

I kept trying to add it to the endpoint, and failing miserably. So much time spent back-and-forth on this!

That’s it for this instalment of “WCF is great, but I wish the config was a bit easier to understand”. Stay tuned for more exciting episodes!

I’m looking for a few folks to group together to get a dedicated Windows server.

Server Details:

• CPU: Intel Xeon 3060 (Dual Core)
• RAM: 2GB
• HDD: 2x 250GB (not RAID)
• Network Port: 100Mbit
• Bandwidth Quota: 2500GB per month
• OS: Windows Server 2003 R2  (x32)
• Other Software: .NET 1.1, plus .NET 2.0 to  .NET 3.5.  MS SQL Server 2005 (Express),

The server would be hosted by The Planet (unless you know of a better place?) in the US.

Because there’s 10 IPs allocated, the way I thought it would be set up would be to have one IP for any shared web hosting, etc - plus remote access in. And one IP would be dedicated to a Linux VM Server (for any apache + php + mysql things you want to run).

Then the rest of the IPs would be split up between the  folks sharing the server - for any other things you wanted to do (FTP server,  etc)

Bandwidth, Diskspace and RAM wouldn’t be strictly controlled, but if the performance of the server is suffering, we’re out of disk space, or we’ve got an over-usage charge, then those who’re using far more than their quota will need to pay up (for bandwidth) or reduce their usage (for diskspace and RAM)  

You’d also be expected to know how to use manage IIS properly, and if you’re hosting stuff on the Linux VM, Apache too.  Oh, and also how to use common sense not to stuff with other people’s settings without their OK.

I shouldn’t need to mention this, but you’ll also be responsible for ensuring that you’re not doing anything illegal under US or Australian laws. So - no torrent downloads, thanks.

Total cost per month for the server setup above is USD$230/month. I’m prepared to pay about USD$80/month, so I’m looking for 3-4 people willing to split about USD$150/month.

So, for about $10/month you’d get an allocation of about 100GB of bandwidth quota, and 20GB/disk space (10GB per drive).  IPs would be divvied up based on % of contribution, after I’ve got enough people onboard, but you’d get at least one IP.

So, if you’re interested - add me on MSN - will@hughesfamily.net.au and let me know.

Update: I now have two other people who’re onboard, and another who’s interested…  I need another four people who’re interested in putting in about USD$30/month each.

If that doesn’t happen, then I guess we’ll have to look at trying to get a smaller server, but this is pretty much as small as it gets before things stop being useful.

Today I spent about half an hour banging my head against this problem:
Whenever I would try and return a business object, I’d simply get no response from my WCF Service. Litterally nothing.

The problem turned out to be that I had accidentally specified the DataMember Name of a property in a sub object twice.

So, I had my broken class set up like:


[DataContract(Name = "MyClass", Namespace = "Example")]
public partial class MyClass
{
[DataMember(Name = "property1")] public int Property1 { get; set; }
[DataMember(Name = "property1")] public string Property2{ get; set; }
}


An instance of this class was used as a property in another object, which was being returned from WCF.

.NET didn’t throw any sort of error unless I tried to return just “MyClass”.

Sure, it was my fault, but if you have a complex data structure, this could get awefully difficult to find without some sort of message from WCF.

Yes, this is part of that ultra nifty WCF JSON .NET 3.5 Flex project at work.

(A note to readers: This is all pure geek/coder content - Please skip this if nothing in the subject line makes sense)

I started on a new project at work for a client a bit over a week ago, by virtue of the requirements, we decided to investigate the use of new version of Microsoft’s  .NET Framework, Version 3.5, for all of the server-side services.

Microsoft have been quite strongly pushing the benefits of the new features of .NET 3.5. There’s been a few key features which are particularly interesting, and if all goes according to the marketing hype, should end up saving a huge amount of time and effort, whilst ensuring that we use well known and standardised interfaces.

What features?

Windows Communications Foundation (WCF) is particularly interesting because it promises to let you (mostly) remove the whole ‘how’ and ‘where’ portion of communications between tiers, and let you focus on the ‘what’ and ‘when’.

In essence, WCF should let me state that I want to create (say) a Web Service, that accepts information in format X, and outputs responses in some other format. It doesn’t have to be a Web Service either, it could be a Peer to Peer network speaking in straight binary streams.

For this project the client-functionality is all in Flex, so we need to ensure that the Flex guys can quickly decode all the responses and turn them into Action Script objects. Through a bit of experimenting and application prior experience - Web Services speaking JSON appeared to be the easiest and most light weight method of doing this.

Language Integrated Queries (LINQ) is another particularly interesting technology, particularly because it lets me focus on what I want to do with the data I have, rather than spending time transforming it from the Database tables, rows, and procedures, into .NET objects and methods.

There are a number of implementations of LINQ, which enables you to query a variety of sources - the one that I’m most likely to use is LINQ to SQL (talking to SQL Server). Regardless of what I’m accessing however, the syntax is identical - again, removing the need to modify my code if I need to query an XML file, Oracle or MySQL Database, or even native .NET objects.

You can probably see a common theme here - WCF lets me focus on communication with the outside world without needing to write that interface or conversion functionality, and LINQ lets me access and manipulate data, without needing to write that interface either.

So, it’s all plug and play?

Well, that depends entirely on what you’re doing with your data. If you’ve got something like a CRM application where the client is responsible for managing (most of) the data, then yes it can quite possibly be almost plug and play if you’re going with a “CRUD” interface.

If your data structure is more complex, then you need to determine exactly where the split is. In this specific project, I’m presenting an abstracted view of the data that the client needs, and doing all of the business logic to manage data management in the SQL and Web Services Layer.

So far, the whole WCF and LINQ combination looks good. I’m hoping to post some more detailed posts later on.

Further Reading

I highly recommend Scott Guthrie’s LINQ to SQL series of posts. Start with Part 1: Introduction to LINQ to SQL

These resources have also been of a great help in getting my head around the whole LINQ thing:

• Kirk Allen Evans’s Blog : Using WCF, JSON, LINQ, and AJAX: Passing Complex Types to WCF Services with JSON Encoding
• Programming JSON with WCF in .NET Framework 3.5
• LINQ to SQL - 5 Minute Overview - Hooked on LINQ
• WCF + LINQ? - Rudi Grobler
• Talking to WCF with Flex 3 via JSON or XML

Last week I went to Microsoft’s “Heroes Happen {Here} 2008″ launch of the 2008 series of products: Windows Server 2008, SQL Server 2008, and Visual Studio 2008.

As part of the ‘goodies bag’ given away, I got a complementary copy of Windows Server 2008 Enterprise Edition. Having read very good things about it, and being rather impressed - I installed it on my work desktop machine. (Rather risky, I know).

I would highly recommend anyone considering this to read Vijayshinva Karnure’s blog post on how to configure it properly. Once done, it looks and “feels” just like Windows Vista. (Only, significantly faster).

However - the first thing I would recommend you do is to turn off the Enhanced Security settings for Internet Explorer. Microsoft have changed the way this is done from Windows Server 2003, so it can take some hunting to find how to change it.

The frustrating thing is that it’s right infront of you. No, really - The Server Manager console that shows on first login has the option right there, but “helpfully” disguises it in acronym form.

Click on that link, and turn off IE ESC for both Admins and Users.