New Blog Format!
Hi, I am working on a new blog format. As I am lazy and a complete html and CSS noob, it will take a while. Please, feel free to comment on the new look. Actually, feel obligated to do so! :)
Sunday, 30 November 2008
Windows Azure
I went to this presentation of a new Microsoft concept called Windows Azure. Well, it is not so much as a new concept, more like them entering the distributed computing competition. Like Google, IBM and - most notably - Amazon before it, Microsoft is using large computer centers to provide storage and computing as services. So, instead of having to worry about buying a zillion computers for your web farm, manage the failed components, the backups, etc. you just rent the storage and computing and create an application using the Windows Azure SDK.
As explained to me, it makes sense to use a large quantity of computers, especially structured for this cloud task, having centralized cooling, automated update, backup and recovery management, etc, rather than buying your own components. More than that. since the computers run the tasks of all customers, there is a more efficient use of CPU time and storage/memory use.
You may pay some extra money for the service, but it will closely follow the curve of your needs, rather than the ragged staircase that is usually a self managed system. You see, you would have to buy all the hardware resources for the maximum amount of use you expect from your application. Instead, with Azure, you just rent what you need and, more importantly, you can unrent when the usage goes down a bit. What you need to understand is that Azure is not a hosting service, nor a web farm proxy. It is what they call cloud computing, the separation of software from hardware.
Ok, ok, what does one install and how does one code against Azure? There are some SDKs. Included is a mock host for one machine and all the tools needed to build an application that can use the Azure model.
What is the Azure model? You have your resources split into storage and computing workers. You cannot access the storage directly and you have no visual interface for the computing workers. All the interaction between them or with you is done via REST requests, http in other words. You don't connect to SQL Servers, you use SQL Services, and so on and so on.
Moving a normal application to Azure may prove difficult, but I guess they will work something out. As with any new technology, people will find novell problems and the solutions for them.
I am myself unsure of what is the minimum size of an application where it becomes more effective to use Azure rather than your own servers, but I have to say that I like at least the model of software development. One can think of the SDK model (again, using only REST requests to communicate with the Azure host) as applicable to any service that would implement the Azure protocols. I can imagine building an application that would take a number of computers in one's home, office, datacenter, etc and transforming them into an Azure host clone. It wouldn't be the same, but assuming that many of your applications are working on Azure or something similar, maybe even a bit of the operating system, why not, then one can finally use all those computers gathering dust while sitting with 5% CPU usage or not even turned on to do real work. I certainly look forward to that! Or, that would be really cool, a peer to peer cloud computing network, free to use by anyone entering the cloud.
As explained to me, it makes sense to use a large quantity of computers, especially structured for this cloud task, having centralized cooling, automated update, backup and recovery management, etc, rather than buying your own components. More than that. since the computers run the tasks of all customers, there is a more efficient use of CPU time and storage/memory use.
You may pay some extra money for the service, but it will closely follow the curve of your needs, rather than the ragged staircase that is usually a self managed system. You see, you would have to buy all the hardware resources for the maximum amount of use you expect from your application. Instead, with Azure, you just rent what you need and, more importantly, you can unrent when the usage goes down a bit. What you need to understand is that Azure is not a hosting service, nor a web farm proxy. It is what they call cloud computing, the separation of software from hardware.
Ok, ok, what does one install and how does one code against Azure? There are some SDKs. Included is a mock host for one machine and all the tools needed to build an application that can use the Azure model.
What is the Azure model? You have your resources split into storage and computing workers. You cannot access the storage directly and you have no visual interface for the computing workers. All the interaction between them or with you is done via REST requests, http in other words. You don't connect to SQL Servers, you use SQL Services, and so on and so on.
Moving a normal application to Azure may prove difficult, but I guess they will work something out. As with any new technology, people will find novell problems and the solutions for them.
I am myself unsure of what is the minimum size of an application where it becomes more effective to use Azure rather than your own servers, but I have to say that I like at least the model of software development. One can think of the SDK model (again, using only REST requests to communicate with the Azure host) as applicable to any service that would implement the Azure protocols. I can imagine building an application that would take a number of computers in one's home, office, datacenter, etc and transforming them into an Azure host clone. It wouldn't be the same, but assuming that many of your applications are working on Azure or something similar, maybe even a bit of the operating system, why not, then one can finally use all those computers gathering dust while sitting with 5% CPU usage or not even turned on to do real work. I certainly look forward to that! Or, that would be really cool, a peer to peer cloud computing network, free to use by anyone entering the cloud.
Saturday, 22 November 2008
Dexter in the Dark - Jeff Lindsay
Well, I just said I can't wait for the third book, haven't I? :) Anyway, Dexter in the Dark was a bit of a disapointment to me. Apparently, Dexter's inner demons are just that, demons, liked to some ancient deity from the times of Solomon called Moloch which is like an alien parasite thing. Really... What did Lindsay do? Read Snow Crash? Watch Fallen? Try to mix Stargate Goa'ulds with Wicker Man and Eyes Wide Shut? Geez!When I was getting so comfortable with the character of Dexter, thinking that Jeff Lindsay was a genius for portraying a type of character I was always thinking of writing, he just takes all that inner maniacal urge that both empowered and limited the character and transforms it into an external, fantasy like thing. Bad writer, bad!
Anyway, that doesn't mean I didn't enjoy the book. I just think that when the third series of the TV show became too far fetched, they were still safe when compared to it. I mean, until now Dexter was a brilliant guy with a dark path and also with a sort of artificial morality, mix in some police stuff, some blood spatter, the weird police seargent sister. It was a perfect setting for introspection and solitary struggle. I loved that! And now demons? As Doakes would have put it "the hell for?".
The fourth Dexter book is supposedly due for february 5th 2009. I hope Lindsay abandons the weird supernatural crap and instead focuses on Dexter's training of his adoptive children into the art of killing. Otherwise I can only see it turn toward so many bad directions like Blade or Hellboy or other green "hybrid saves the planet" thing.
Dearly Devoted Dexter - Jeff Lindsay
Dearly Devoted Dexter is much darker than the first Dexter book. Maybe it is just because all the facts about Dexter are clear and it starts with a gruesome murder, insane special forces style. The title comes from the fact that he helps his sister, now partially in the loop about his Dark Passenger, to solve the newest serial killer case. Of course, Deb, now a seargent after Laguerta has died, has a personal stake in this, since one of the people the murderer abducted and intends to do bad things to, is her boyfriend, with whom she is very much in love.It is interesting to develop the Dexter character in this way, especially since he is described as totally indifferent to the horrible fate of people he doesn't care about, yet he is still compelled to help his sister out.
I was a bit disapointed by the police work involved. If I were to believe Lindsay, the Miami police are a bunch of morons, following (badly) a set of procedures without any real talent other than badmouthing.
Elements from this second book in the Dexter series were clearly used in the series, but it is already a completely different story. The FBI agent that Deborah briefly dates in the series was inspired by the character of Kyle, shady government agent that she falls in love with in this book. The stalking of Dexter by the grumpy seargent Doakes is also mirrored from this book, although the motives and the outcome are completely different.
Again, the series evolves the Dexter character more and the story is more complex than the book, but by now it is obvious the TV show and the book are going in completely different directions.
All in all, a bit better than the first, darker, but also funnier. I have never laughed as much reading a book for a long time. Can't wait for the third book now.
Friday, 21 November 2008
StringBuilder substring?
Well, it may have been obvious for many, but I had no idea. Whenever I was writing a piece of code that uses a StringBuilder I was terribly upset by the lack of a substring method.
It was there all along, only it is the ToString method. You give it the startIndex and length and you're set.
Looking at the source, I see that in .Net 1.1 this method is only a normal Substring on the internal string used by the string builder. In Net 2.0, the method uses a InternalSubStringWithChecks internal method of the string class, which is using a InternalSubString unsafe method that seems to be more basic and thus faster.
It was there all along, only it is the ToString method. You give it the startIndex and length and you're set.
Looking at the source, I see that in .Net 1.1 this method is only a normal Substring on the internal string used by the string builder. In Net 2.0, the method uses a InternalSubStringWithChecks internal method of the string class, which is using a InternalSubString unsafe method that seems to be more basic and thus faster.
Thursday, 20 November 2008
Darkly Dreaming Dexter - Jeff Lindsay
I have been watching this TV Series called Dexter and slowly but surely I fell in love with it. It features a psychopathic serial killer that has a hobby of killing other killers. The story is long and I suggest you watch it to get it fully. Anyway, the series has reached season 3 and stars Michael C. Hall, which you may recognize from the Six Feet Under TV series. I've also noticed that the series is based on a book! So, naturally, I got the book and started reading it. It's Michael C. Hall on the cover there.Darkly Dreaming Dexter is the first in a series of Dexter books by Jeff Lindsay. While it starts pretty much the same as the series, the series quickly moves away from the script in the book. However, the spirit is there, even if, of course, they had to make the lead character a little more likable in the series and the whole thing less bloody.
Imagine an emotionless killer, raised by his cop father to kill according to a code and also to be thorough and attentive to the details so that the police wouldn't catch him. He is also working for the Miami police department as a blood spatter analyst. The inner dialogues are really delicious, the way he sees the world as a cynical dark Data is both funny and deep. Lindsay manages to portray an alien being, silently watching the world we take for granted, hunting on the edge of our own morality.
And while I do enjoy the book, I have to say that the series is more complex and the story a bit more realistic. So, there, finally a movie or series that surpasses the book!
Wednesday, 19 November 2008
Cascading Dropdowns and 'Invalid postback or callback argument' error
Actually, I think this applies to any dynamic modification of drop down list options. Read on!
I have used a CascadingDropDown extender from the AjaxControlToolkit to select regions and provinces based on a web service. It was supposed to be painless and quick. And it was. Until another dev showed me a page giving the horribly obtuse 'Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.'. As you can see, this little error message basically says there is a problem with a control, but doesn't care to disclose which. There are no events or overridable methods to enable some sort of debug.
Luckily, Visual Studio 2008 has source debug inside the .Net framework itself. Thus I could see that the error is caused by the drop down lists I mentioned above. Google told me that somewhere in the documentation of the CascadingDropDown extender there is a mention on setting enableEventValidation to false. I couldn't find the reference, but of course, I didn't look too hard, because that is simply stupid. Why disable event validation for the entire page because of a control? It seems reasonable that Microsoft left it enabled for a reason. (Not that I accuse them of being reasonable, mind you).
Analysing further, I realised that the error kind of made sense. You see, the dropdownlists were not binded with data that came from a postback. How can one POST a value from a select html element if the select did not have it as an option? It must be a hack. Well, of course it was a hack, since the cascade extender filled the dropdown list with values.
I have tried to find a way to override something, make only those two dropdownlists not have event validation enabled. Couldn't find any way to do that. Instead, I've decided to register all possible values with Page.ClientScript.RegisterForEventValidation. And it worked. What I don't understand is why did this error occur only now, and not in the first two pages I have built and tested. That is still to be determined.
It should be used in a Render override, since the RegisterForEventValidation method only allows its use in the Render stage of the page cycle.
And that is it. Is it ugly to load all possible values in order to validate the input? Yes. But how else could you validate the input? A little more work and a hidden bug that appears when you least expect it, but now even the input from those drop downs is more secure.
Update:
My control was used in two pages with EnableEventValidation="false" and that's why it didn't throw any error. Anyway, I don't recommend setting it to false. Use the code above. BUT, if you don't know where the code goes or you don't understand what it does, better use this solution and save us both a lot of grief.
I have used a CascadingDropDown extender from the AjaxControlToolkit to select regions and provinces based on a web service. It was supposed to be painless and quick. And it was. Until another dev showed me a page giving the horribly obtuse 'Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.'. As you can see, this little error message basically says there is a problem with a control, but doesn't care to disclose which. There are no events or overridable methods to enable some sort of debug.
Luckily, Visual Studio 2008 has source debug inside the .Net framework itself. Thus I could see that the error is caused by the drop down lists I mentioned above. Google told me that somewhere in the documentation of the CascadingDropDown extender there is a mention on setting enableEventValidation to false. I couldn't find the reference, but of course, I didn't look too hard, because that is simply stupid. Why disable event validation for the entire page because of a control? It seems reasonable that Microsoft left it enabled for a reason. (Not that I accuse them of being reasonable, mind you).
Analysing further, I realised that the error kind of made sense. You see, the dropdownlists were not binded with data that came from a postback. How can one POST a value from a select html element if the select did not have it as an option? It must be a hack. Well, of course it was a hack, since the cascade extender filled the dropdown list with values.
I have tried to find a way to override something, make only those two dropdownlists not have event validation enabled. Couldn't find any way to do that. Instead, I've decided to register all possible values with Page.ClientScript.RegisterForEventValidation. And it worked. What I don't understand is why did this error occur only now, and not in the first two pages I have built and tested. That is still to be determined.
It should be used in a Render override, since the RegisterForEventValidation method only allows its use in the Render stage of the page cycle.
And that is it. Is it ugly to load all possible values in order to validate the input? Yes. But how else could you validate the input? A little more work and a hidden bug that appears when you least expect it, but now even the input from those drop downs is more secure.
Update:
My control was used in two pages with EnableEventValidation="false" and that's why it didn't throw any error. Anyway, I don't recommend setting it to false. Use the code above. BUT, if you don't know where the code goes or you don't understand what it does, better use this solution and save us both a lot of grief.
