Posts archived in .NET

This is the first in (hopefully) a series of quick things I’ve picked up whilst tackling the previously mentioned project

So, I have a table something like this:

CREATE TABLE [dbo].[Product](
 
[ProductID] [int] IDENTITY(1,1) NOT NULL,
 
[Name] [nvarchar](100) NOT NULL,
   [Price] [int] NOT NULL,
    [LastSaveTimestamp] [datetime] NOT NULL CONSTRAINT [DF_Product_SaveTimestampDEFAULT (getutcdate())
) ON [PRIMARY]

The key here is the default value on the column: LastSaveTimestamp.

If I then try to, say insert a new column into this table, for example using this code:

  DatabaseContext dc = new DatabaseContext();
  Product product = new Product();
  product.Name = “test product”;
  product.Price = 50;
  dc.Products.InsertOnSubmit(product);
  dc.SubmitChanges(System.Data.Linq.ConflictMode.FailOnFirstConflict);

Then I’d get an exception like:

System.Data.SqlTypes.SqlTypeException: SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM..

The fix is actually really simple – In the table designer / DBML, you need to tell it that the column is auto-generated. Unfortunately this doesn’t seem to be automatically detected. It’s one of a few ‘just plain weird’ situations. 

AzamSharp has the fix details, with a handy-dandy screenshot over on his blog.

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Two WCF Stumbles

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.

image

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

debugging-wcf-services

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:

Those following me on Twitter have had the joy of seeing random messages about the ongoing issues I’ve had getting my ADSL2+ connected.

Since the last post on this (on the 13th of Feb) I basicly gave up on calling iiNet – I’d already spent a fortune in mobile costs listening to their hold music, and was just waiting for them to get back to my support-enquiry email. (I never did get a response to that)

However, last Friday (22nd) as I was going to bed at about 1:30am (Okay, so technically Saturday morning) I noticed that my DSL Router was saying it had sync. I normally check the router panel when I get home, so I must’ve missed it that night. I stayed up about an hour setting up a bunch of tests to see how fast/stable the connection was. I left these tests to continue running whilst I slept. When I left home on Saturday at about 9AM it was still running, and I was feeling somewhat optimistic that it might continue to work. Of course, Murphy was listening, and when I got home at around 5pm, I had lost line sync once again.

Sunday I called iiNet again, this time because their Toolbox said there should only be about a 7min wait. The tech guy tried a few things from their end, but once again no success – and said he’d put the request through to their Fault Manager who would try to get VisionStream to narrow down the timeframe.

Come Monday morning, I get a call from Christy at Vision Stream, “Is Wednesday suitable for you?”. Grr. Same situation as last time Christy called me! Looking at the iiNet Toolbox – what do you know, a 45min or so wait on hold, again. Instead of doing that, I try another tact – go straight to the top.

So, I write a pleading email to Michael Malone, the Managing Director of iiNet. He’s quite active on Whirlpool’s forums, and makes his email available there. I give a bunch of possible ways we could try and work together, such as asking for the first/last timeslot on the day, getting a call an hour or two beforehand, and even offering to pay for a Saturday callout if necessary.

Tuesday I get a call from Rebecca at iiNet regarding the email, she’s called VisionStrem and tried getting them to go with any of the options I presented – no luck. I think up one last option – asking the Tech to call me as he’s starting the job before mine. Rebecca thinks it might work, and goes back to VisionStream.

Today, (Wednesday) Rebecca calls back – VisionStream won’t go for it, despite having escalated it up the chain of management there. Apparently VisionStream started quoting sections of the Telecommunications Act to her, and stating that “we treat all customers equally”. However, the VisionStream manager has agreed to commit to a particular timeslot (9AM-12:30PM or 12PM to 6PM), AND to get the Tech to call an hour beforehand.

I ask Rebecca what the chances are of switching to a regular ADSL2 service (and having the line connected as a standard phone again) – apparently it can be done, but I’d be the first to have tried it. And the time it would take would probably be somewhere up around a month, assuming everything went according to play.

So, for now Rebecca is sending the case back to VisionStream, and getting them to commit to providing a 9AM-12:30PM timeslot for this job plus the hour-before call.

Here’s hoping that VisionStream can come through on this!

Side Rant:
VisionStream’s comment to Rebecca that they treat all customers equally, is rather stupid. Yes, they treat all customers equally poorly. VisionStream’s view is apparently that All customers’ time is worth nothing, and they obviously have nothing better to do.

Surely someone at VisionStream can see that doing this just gives them a really poor reputation.

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Killing with Kindness

We killed Twitter, again.

This time it was from an excess of Love – Of the less-than-three (“<3") variety.

My screen was filled with hundreds of messages like these two:
Less than Three’s for everyone.

For the non-Twitter’ers out there, the Twitter folks added a way to send a special type of tweet. By entering “@username <3" - it would transform the ordinary tweet, into this special type of message.

It also results in that person getting a "Do you love (sender)?" prompt, with a button to quickly reply.

This novelty, combined with the easy reply, lead to a major increase in the number of Tweets for valentines day, and thus Twitter slowing down / refusing to respond for many people (including me).

Edit: Here's a better screenshot of what was/is going on (read from bottom up)

Less than 3 (more)

Someone asked me recently what my opinion of Dreamhost was. They knew I use Dreamhost for a variety of sites, and were looking to sign up.

The short answer is that Dreamhost are “variable”.

I’ve been a Dreamhost customer for about 3 years now, and I’ve seen some pretty wild thing happen.

They’ve had several major power outages which took down their entire datacentre. They’ve had significant network issues for a period of months. They had a major data security breach where someone managed to get several thousand usernames and passwords. And, to top it all off – they recently overcharged about half of their customers by several million US peso dollars. (It would have been up around 10 million, if it wern’t for a bug in their software).

Oh, and it’s probably worth mentioning that as I write this, all my sites are down, because the servers they’re on are being driven from one side of LA to the other.

Given all of the above, most ordinary, sane people would probably be shouting “run for the hills!” at the top of their lungs. And, in many cases people would be  quite justified to run as far as they could from Dreamhost.

Here’s the thing, however – apart from the power issues (and the scheduled cluster move mentioned) my sites have worked just fine for the most part. 

Yeah, there’s been times when a server has been down, or when some sort of glitch has slowed things down – but lets look at the big picture here for a second.

Dreamhost’s business is to sell reasonable quality webhosting, with large gobs of disk space and bandwidth, at a very cheap rate.  I pay something like USD$20/month (on the old plans) for my Dreamhost service. 

What do I get for that USD$20/month?  I get to host 30-something sites, occupying 20GB of disk space, and transferring about 150GB per month. No, that’s not the limit, that’s what I’m actually using. This month. Dreamhost have absolutely no issue with me using a lot more than that – even if I went to TWENTY times that, I’d still be well under the limits of my account.

I also get the security that someone else will take care of the servers, and keep them patched and secure. In the event that something goes wrong, I can lodge a ticket and have someone else fix it at 3am.

So, does that mean I’d recommend Dreamhost to everyone? Heck no – there’s heaps of situations where I wouldn’t recommend Dreamhost.

Any time you answer “yes” or even “maybe” to the question “Will this being unavailable impact my business?”, you need to be looking at a managed hosting solution with a proper contract/service level agreement.  Don’t pass go, don’t collect $200, and definitely don’t try reselling this to your customers.

Dreamhost are also not suitable for a variety of “big” applications/sites – despite the label saying you can get 5TB of bandwidth and 500GB of disk space, actually using all of it is possible only under very specific conditions. Most of the time, anyone running a site that is that popular is going to be using so much of the resources on their server that they’re going to be causing issues for other users on the same server.

It’s like the speedo on your car, if you’re actually hitting 240KPH or 30,000RPM, something is going very very wrong, or is about to.

So, with that out of the way – I am actually starting to look for some dedicated server options – not because I don’t like Dreamhost (I do) – but simply because I want to do other things that I simply can’t do with Dreamhost.

My options are limited, because I want to be able to manage the server myself, I need a reasonably large amount of disk space and bandwidth quota, and I need to run Windows.

What are your experiences with Dreamhost, and/or dedicated hosting?

I’ve been frustrated for a while trying to use various products and services. I thought I’d compress all of them into a single post.

Click through to read this collection of rantings…

Read the rest of this entry »

For over five years, I’ve held a bit of an open secret: I’m an alien from fluidic space.

Err, wait, let me start that again.

For over five years, I’ve been working for Telstra. I started off “on the phones”, working in a service call centre. Due to me being a smart-ass (and critical of some very inefficient systems) I was taken off the phones after about two weeks, to write some reporting tools.

From that first app in Excel 97 using VBA to generate charts, I converted to a full-time employee, and went on to bigger and better things. When I wrote that there’s a reasonably good chance of my code having touched your life in some subtle way, I wasn’t joking. The software I wrote helps people in Telstra do their jobs: Routing messages, generating reports, storing data, and keeping an eye on other applications.
I’m proud of the work I’ve done, despite it not being world changing or highly visible. Sure there’s some icky bits (VBA, Oracle, MS Access, Classic ASP), but overall I hope that it’s made people’s lives better, and/or their jobs easier, in some small way.

Today, I resigned from my position at Telstra. It’s not something I did lightly, but, after consideration I’ve decided I need to move on.

For those that are curious, I’m not going to be unemployed – Today I’ve also accepted a contract role to a digital media company in Sydney. I won’t say who, yet, until I’ve had a chance to speak with them some more, but suffice to say it looks like a great company to work for, doing interesting things and meeting interesting people.

Oh, and yes, this means that I’ll be moving from Newcastle / Toronto. I’m still at Telstra until the 26th of October and then I’ll be off to Sydney and new things.

I’d also like to throw a quick shout-out to Nick Hodge for putting in a good word for me, and listening to me rant a little about work; Jack Greenrich for plenty of coding advice and guidance; Ian Ward for getting me hired at Telstra and started down the software development path; and both Markus Hafner and Greg Dwyer of Happener Recruitment for helping me to get this new position.

Exciting times ahead, for sure…