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  • Creating a simple RSS reader using ListView,XMLDatasource,DataPager web server controls

    - by nikolaosk
    In my last ASP.Net seminar someone noticed that we did not talk at all about the XmlDataSource,ListView,DataPager web server controls. It is rather impossible to investigate/talk about all issues regarding ASP.Net in a seminar but I promised to write a blog post. I thought that I could combine all those three web server controls to create a RSS reader. 1) Launch Visual Studio 2008/2010. Express editions will work fine. 2) Create an empty asp.net web site. Choose an appropriate name. We will not write...(read more)

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  • Subterranean IL: Exception handler semantics

    - by Simon Cooper
    In my blog posts on fault and filter exception handlers, I said that the same behaviour could be replicated using normal catch blocks. Well, that isn't entirely true... Changing the handler semantics Consider the following: .try { .try { .try { newobj instance void [mscorlib]System.Exception::.ctor() // IL for: // e.Data.Add("DictKey", true) throw } fault { ldstr "1: Fault handler" call void [mscorlib]System.Console::WriteLine(string) endfault } } filter { ldstr "2a: Filter logic" call void [mscorlib]System.Console::WriteLine(string) // IL for: // (bool)((Exception)e).Data["DictKey"] endfilter }{ ldstr "2b: Filter handler" call void [mscorlib]System.Console::WriteLine(string) leave.s Return } } catch object { ldstr "3: Catch handler" call void [mscorlib]System.Console::WriteLine(string) leave.s Return } Return: // rest of method If the filter handler is engaged (true is inserted into the exception dictionary) then the filter handler gets engaged, and the following gets printed to the console: 2a: Filter logic 1: Fault handler 2b: Filter handler and if the filter handler isn't engaged, then the following is printed: 2a:Filter logic 1: Fault handler 3: Catch handler Filter handler execution The filter handler is executed first. Hmm, ok. Well, what happens if we replaced the fault block with the C# equivalent (with the exception dictionary value set to false)? .try { // throw exception } catch object { ldstr "1: Fault handler" call void [mscorlib]System.Console::WriteLine(string) rethrow } we get this: 1: Fault handler 2a: Filter logic 3: Catch handler The fault handler is executed first, instead of the filter block. Eh? This change in behaviour is due to the way the CLR searches for exception handlers. When an exception is thrown, the CLR stops execution of the thread, and searches up the stack for an exception handler that can handle the exception and stop it propagating further - catch or filter handlers. It checks the type clause of catch clauses, and executes the code in filter blocks to see if the filter can handle the exception. When the CLR finds a valid handler, it saves the handler's location, then goes back to where the exception was thrown and executes fault and finally blocks between there and the handler location, discarding stack frames in the process, until it reaches the handler. So? By replacing a fault with a catch, we have changed the semantics of when the filter code is executed; by using a rethrow instruction, we've split up the exception handler search into two - one search to find the first catch, then a second when the rethrow instruction is encountered. This is only really obvious when mixing C# exception handlers with fault or filter handlers, so this doesn't affect code written only in C#. However it could cause some subtle and hard-to-debug effects with object initialization and ordering when using and calling code written in a language that can compile fault and filter handlers.

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  • Keep taking the tablets

    - by Roger Hart
    A guest editorial for the SimpleTalk newsletter. So why would Red Gate build an Ipad Game? Is it just because tablet devices are exciting and cool? Ok, maybe a little. Mostly, it was seeing that the best existing tablet and smartphone apps do simple, intuitive things, using simple intuitive interfaces to solve single problems. That's pretty close to what we call our own "intuitively simple" approach to software. Tablets and mobile could be fantastic for us, if we can identify those problems that a tablet device can solve. How do you create THE next tool for a completely new technology? We're glad we don't face that problem every day, but it's pretty exciting when we do. We figure we should learn by doing. We created "MobileFoo" (a Red Gate Company) , we picked up some shiny Apple tech, and got to grips with Objective C, and life in the App Store ecosystem. The result so far is an iPad game: Stacks and Heaps It's Rob and Marine's spin on Snakes and Ladders. Instead of snakes we have unhandled exceptions, a blue screen of death, and other hazards. We wanted something compellingly geeky on mobile, and we're pretty sure we've got it. It's trudging through App Store approval as we speak. but if you want to get an idea of what it is like to switch from .net to Objective C, take a look at Rob's post Android and iOS is quite a culture-change for Windows developers. So to give them a feel for the problems real users might have, we needed some real users - we offered our colleagues subsidised tablets. The only conditions were that they get used at work, and we get the feedback. Seeing tablets around the office is starting to give us some data points: Is typing the bottleneck? Will tablets ever cut it as text-entry devices, and could we fix it? Is mobile working held up by the pain of connecting to work LANs? How about security? Multi-tasking will let tablets do more. They're small, easy to use, almost instant to switch on, and connect by Wi Fi. There's plenty on that list to make a sysadmin twitchy. We'll find out as people spend more time working with these devices, and we'd love to hear what you think about tablet devices too. (comments are filtered, what with the spam)

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  • Who writes the words? A rant with graphs.

    - by Roger Hart
    If you read my rant, you'll know that I'm getting a bit of a bee in my bonnet about user interface text. But rather than just yelling about the way the world should be (short version: no UI text would suck), it seemed prudent to actually gather some data. Rachel Potts has made an excellent first foray, by conducting a series of interviews across organizations about how they write user interface text. You can read Rachel's write up here. She presents the facts as she found them, and doesn't editorialise. The result is insightful, but impartial isn't really my style. So here's a rant with graphs. My method, and how it sucked I sent out a short survey. Survey design is one of my hobby-horses, and since some smartarse in the comments will mention it if I don't, I'll step up and confess: I did not design this one well. It was potentially ambiguous, implicitly excluded people, and since I only really advertised it on Twitter and a couple of mailing lists the sample will be chock full of biases. Regardless, these were the questions: What do you do? Select the option that best describes your role What kind of software does your organization make? (optional) In your organization, who writes the text on your software user interfaces? (for example: button names, static text, tooltips, and so on) Tick all that apply. In your organization who is responsible for user interface text? Who "owns" it? The most glaring issue (apart from question 3 being a bit broken) was that I didn't make it clear that I was asking about applications. Desktop, mobile, or web, I wouldn't have minded. In fact, it might have been interesting to categorize and compare. But a few respondents commented on the seeming lack of relevance, since they didn't really make software. There were some other issues too. It wasn't the best survey. So, you know, pinch of salt time with what follows. Despite this, there were 100 or so respondents. This post covers the overview, and you can look at the raw data in this spreadsheet What did people do? Boring graph number one: I wasn't expecting that. Given I pimped the survey on twitter and a couple of Tech Comms discussion lists, I was more banking on and even Content Strategy/Tech Comms split. What the "Others" specified: Three people chipped in with Technical Writer. Author, apparently, doesn't cut it. There's a "nobody reads the instructions" joke in there somewhere, I'm sure. There were a couple of hybrid roles, including Tech Comms and Testing, which sounds gruelling and thankless. There was also, an Intranet Manager, a Creative Director, a Consultant, a CTO, an Information Architect, and a Translator. That's a pretty healthy slice through the industry. Who wrote UI text? Boring graph number two: Annoyingly, I made this a "tick all that apply" question, so I can't make crude and inflammatory generalizations about percentages. This is more about who gets involved in user interface wording. So don't panic about the number of developers writing UI text. First off, it just means they're involved. Second, they might be good at it. What? It could happen. Ours are involved - they write a placeholder and flag it to me for changes. Sometimes I don't make any. It's also not surprising that there's so much UX in the mix. Some of that will be people taking care, and crafting an understandable interface. Some of it will be whatever text goes on the wireframe making it into production. I'm going to assume that's what happened at eBay, when their iPhone app purportedly shipped with the placeholder text "Some crappy content goes here". Ahem. Listing all 17 "other" responses would make this post lengthy indeed, but you can read them in the raw data spreadsheet. The award for the approach that sounds the most like a good idea yet carries the highest risk of ending badly goes to whoever offered up "External agencies using focus groups". If you're reading this, and that actually works, leave a comment. I'm fascinated. Who owned UI text Stop. Bar chart time: Wow. Let's cut to the chase, and by "chase", I mean those inflammatory generalizations I was talking about: In around 60% of cases the person responsible for user interface text probably lacks the relevant expertise. Even in the categories I count as being likely to have relevant skills (Marketing Copywriters, Content Strategists, Technical Authors, and User Experience Designers) there's a case for each role being unsuited, as you'll see in Rachel's blog post So it's not as simple as my headline. Does that mean that you personally, Mr Developer reading this, write bad button names? Of course not. I know nothing about you. It rather implies that as a category, the majority of people looking after UI text have neither communication nor user experience as their primary skill set, and as such will probably only be good at this by happy accident. I don't have a way of measuring those frequency of those accidents. What the Others specified: I don't know who owns it. I assume the project manager is responsible. "copywriters" when they wish to annoy me. the client's web maintenance person, often PR or MarComm That last one chills me to the bone. Still, at least nobody said "the work experience kid". You can see the rest in the spreadsheet. My overwhelming impression here is of user interface text as an unloved afterthought. There were fewer "nobody" responses than I expected, and a much broader split. But the relative predominance of developers owning and writing UI text suggests to me that organizations don't see it as something worth dedicating attention to. If true, that's bothersome. Because the words on the screen, particularly the names of things, are fundamental to the ability to understand an use software. It's also fascinating that Technical Authors and Content Strategists are neck and neck. For such a nascent discipline, Content Strategy appears to have made a mark on software development. Or my sample is skewed. But it feels like a bit of validation for my rant: Content Strategy is eating Tech Comms' lunch. That's not a bad thing. Well, not if the UI text is getting done well. And that's the caveat to this whole post. I couldn't care less who writes UI text, provided they consider the user and don't suck at it. I care that it may be falling by default to people poorly disposed to doing it right. And I care about that because so much user interface text sucks. The most interesting question Was one I forgot to ask. It's this: Does your organization have technical authors/writers? Like a lot of survey data, that doesn't tell you much on its own. But once we get a bit dimensional, it become more interesting. So taken with the other questions, this would have let me find out what I really want to know: What proportion of organizations have Tech Comms professionals but don't use them for UI text? Who writes UI text in their place? Why this happens? It's possible (feasible is another matter) that hundreds of companies have tech authors who don't work on user interfaces because they've empirically discovered that someone else, say the Marketing Copywriter, is better at it. And once we've all finished laughing, I'll point out that I've met plenty of tech authors who just aren't used to thinking about users at the point of need in the way UI text and embedded user assistance require. If you've got what I regard, perhaps unfairly, as the bad kind of tech author - the old-school kind with the thousand-page pdf and the grammar obsession - if you've got one of those then you probably are better off getting the UX folk or the copywriters to do your UI text. At the very least, they'll derive terminology from user research.

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  • .NET Reflector Pro to the rescue

    Almost all applications have to interface with components or modules written by somebody else, for which you don't have the source code. This is fine until things go wrong, but when you need to refactor your code and you keep getting strange exceptions, you'll start to wish you could place breakpoints in someone else's code and step through it. Now, of course, you can, as Geoffrey Braaf discovered.

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  • New Wine in New Bottles

    - by Tony Davis
    How many people, when their car shows signs of wear and tear, would consider upgrading the engine and keeping the shell? Even if you're cash-strapped, you'll soon work out the subtlety of the economics, the cost of sudden breakdowns, the precious time lost coping with the hassle, and the low 'book value'. You'll generally buy a new car. The same philosophy should apply to database systems. Mainstream support for SQL Server 2005 ends on April 12; many DBAS, if they haven't done so already, will be considering the migration to SQL Server 2008 R2. Hopefully, that upgrade plan will include a fresh install of the operating system on brand new hardware. SQL Server 2008 R2 and Windows Server 2008 R2 are designed to work together. The improved architecture, processing power, and hyper-threading capabilities of modern processors will dramatically improve the performance of many SQL Server workloads, and allow consolidation opportunities. Of course, there will be many DBAs smiling ruefully at the suggestion of such indulgence. This is nothing like the real world, this halcyon place where hardware and software budgets are limitless, development and testing resources are plentiful, and third party vendors immediately certify their applications for the latest-and-greatest platform! As with cars, or any other technology, the justification for a complete upgrade is complex. With Servers, the extra cost at time of upgrade will generally pay you back in terms of the increased performance of your business applications, reduced maintenance costs, training costs and downtime. Also, if you plan and design carefully, it's possible to offset hardware costs with reduced SQL Server licence costs. In his forthcoming SQL Server Hardware book, Glenn Berry describes a recent case where he was able to replace 4 single-socket database servers with one two-socket server, saving about $90K in hardware costs and $350K in SQL Server license costs. Of course, there are exceptions. If you do have a stable, reliable, secure SQL Server 6.5 system that still admirably meets the needs of a specific business requirement, and has no security vulnerabilities, then by all means leave it alone. Why upgrade just for the sake of it? However, as soon as a system shows sign of being unfit for purpose, or is moving out of mainstream support, the ruthless DBA will make the strongest possible case for a belts-and-braces upgrade. We'd love to hear what you think. What does your typical upgrade path look like? What are the major obstacles? Cheers, Tony.

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  • The SmartAssembly Rearchitecture

    - by Simon Cooper
    You may have noticed that not a lot has happened to SmartAssembly in the past few months. However, the team has been very busy behind the scenes working on an entirely new version of SmartAssembly. SmartAssembly 6.5 Over the past few releases of SmartAssembly, the team had come to the realisation that the current 'architecture' - grown organically, way before RedGate bought it, from a simple name obfuscator over the years into a full-featured obfuscator and assembly instrumentation tool - was simply not up to the task. Not for what we wanted to do with it at the time, and not what we have planned for the future. Not only was it not up to what we wanted it to do, but it was severely limiting our development capabilities; long-standing bugs in the root architecture that couldn't be fixed, some rather...interesting...design decisions, and convoluted logic that increased the complexity of any bugfix or new feature tenfold. So, we set out to fix this. Earlier this year, a new engine was written on which SmartAssembly would be based. Over the following few months, each feature was ported over to the new engine and extensively tested by our existing unit and integration tests. The engine was linked into the existing UI (no easy task, due to the tight coupling between the UI and old engine), and existing RedGate products were tested on the new SmartAssembly to ensure the new engine acted in the same way. The result is SmartAssembly 6.5. The risks of a rearchitecture Are there risks to rearchitecting a product like SmartAssembly? Of course. There was a lot of undocumented behaviour in the old engine, and as part of the rearchitecture we had to find this behaviour, define it, and document it. In the process we found some behaviour of the old engine that simply did not make sense; hence the changes in pruning & obfuscation behaviour in the release notes. All the special edge cases we had to find, document, and re-implement. There was a chance that these special cases would not be found until near the end of the project, when everything is functionally complete and interacting together. By that stage, it would be hard to go back and change anything without a whole lot of extra work, delaying the release by months. We always knew this was a possibility; our initial estimate of the time required was '4 months, ± 4 months'. And that was including various mitigation strategies to reduce the likelihood of these issues being found right at the end. Fortunately, this worst-case did not happen. However, the rearchitecture did produce some benefits. As well as numerous bug fixes that we could not fix any other way, we've also added logging that lets you find out exactly why a particular field or property wasn't pruned or obfuscated. There's a new command line interface, we've tested it with WP7.1 and Silverlight 5, and we've added a new option to error reporting to improve the performance of instrumented apps by ~10%, at the cost of inaccurate line numbers in reports. So? What differences will I see? Largely none. SmartAssembly 6.5 produces the same output as SmartAssembly 6.2. The performance of 6.5 will be much faster for some users, and generally the same as 6.2 for the remaining. If you've encountered a bug with previous versions of SmartAssembly, I encourage you to try 6.5, as it has most likely been fixed in the rearchitecture. If you encounter a bug with 6.5, please do tell us; we'll be doing another release quite soon, so we'll aim to fix any issues caused by 6.5 in that release. Most importantly, the new architecture finally allows us to implement some Big Things with SmartAssembly we've been planning for many months; these will fundamentally change how you build, release and monitor your application. Stay tuned for further updates!

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  • An update process that is even worse than Windows updates

    - by fatherjack
    I'm sorry EA but your game update process stinks. I am not a hardcore gamer but I own a Playstation3 and have been playing Battlefield Bad Company 2 (BFBC2) a bit since I got it for my birthday and there have been two recent updates to the game. Now I like the idea of games getting updates via downloadable content. You can buy a game and if there are changes that are needed (service packs if you will) then they can be distributed over the games console network. Great. Sometimes it fixes problems,...(read more)

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  • What Counts For a DBA – Decisions

    - by Louis Davidson
    It’s Friday afternoon, and the lead DBA, a very talented guy, is getting ready to head out for two well-earned weeks of vacation, with his family, when this error message pops up in his inbox: Msg 211, Level 23, State 51, Line 1. Possible schema corruption. Run DBCC CHECKCATALOG. His heart sinks. It’s ten…no eight…minutes till it’s time to walk out the door. He glances around at his coworkers, competent to handle many problems, but probably not up to the challenge of fixing possible database corruption. What does he do? After a few agonizing moments of indecision, he clicks shut his laptop. He’ll just wait and see. It was unlikely to come to anything; after all, it did say “possible” schema corruption, not definite. In that moment, his fate was sealed. The start of the solution to the problem (run DBCC CHECKCATALOG) had been right there in the error message. Had he done this, or at least took two of those eight minutes to delegate the task to a coworker, then he wouldn’t have ended up spending two-thirds of an idyllic vacation (for the rest of the family, at least) dealing with a problem that got consistently worse as the weekend progressed until the entire system was down. When I told this story to a friend of mine, an opera fan, he smiled and said it described the basic plotline of almost every opera or ‘Greek Tragedy’ ever written. The particular joy in opera, he told me, isn’t the warbly voiced leading ladies, or the plump middle-aged romantic leads, or even the music. No, what packs the opera houses in Italy is the drama of characters who, by the very nature of their life-experiences and emotional baggage, make all sorts of bad choices when faced with ordinary decisions, and so move inexorably to their fate. The audience is gripped by the spectacle of exotic characters doomed by their inability to see the obvious. I confess, my personal experience with opera is limited to Bugs Bunny in “What’s Opera, Doc?” (Elmer Fudd is a great example of a bad decision maker, if ever one existed), but I was struck by my friend’s analogy. If all the DBA cubicles were a stage, I think we would hear many similarly tragic tales, played out to music: “Error handling? We write our code to never experience errors, so nah…“ “Backups failed today, but it’s okay, we’ll back up tomorrow (we’ll back up tomorrow)“ And similarly, they would leave their audience gasping, not necessarily at the beauty of the music, or poetry of the lyrics, but at the inevitable, grisly fate of the protagonists. If you choose not to use proper error handling, or if you choose to skip a backup because, hey, you haven’t had a server crash in 10 years, then inevitably, in that moment you expected to be enjoying a vacation, or a football game, with your family and friends, you will instead be sitting in front of a computer screen, paying for your poor choices. Tragedies are very much part of IT. Most of a DBA’s day to day work has limited potential to wreak havoc; paperwork, timesheets, random anonymous threats to developers, routine maintenance and whatnot. However, just occasionally, you, as a DBA, will face one of those decisions that really matter, and which has the possibility to greatly affect your future and the future of your user’s data. Make those decisions count, and you’ll avoid the tragic fate of many an operatic hero or villain.

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  • Conference networking for the socially awkward

    - by Melanie Townsend
    Do you approach a room full of strangers with excitement at all the new people you’re going to chat to over coffee and a muffin as you swap tales of how you convinced your manager to give you the day “off”? Or, do you find rooms full of strangers intimidating and begin by scouting out a place you can stand quietly and not be in someone’s way until the next session begins? If you’re on the train to extrovert city, that’s great, well done, move along. If, on the other hand, a room full of strangers who all seem to inexplicably know each other already is more challenge than opportunity, then making those connections with other professionals can be more difficult. So, here’s some advice, some gleaned from other things I’ve read online when trying to overcome my own discomfort in large groups (hopefully minus the infuriating condescension), others are just things I’ve found helpful over the years. Start small Smaller groups are less intimidating, and, now that you’ve taken the plunge to show up, it’s harder to remain inconspicuous. I find it’s easier to speak to new people once the option NOT to has been taken away. You’re there now, smile through the awkward and you’ll be forever grateful when the three people you’ve met and gotten to know here are also at that gigantic conference later on (ideally, introducing you to other people). Smile, or at the very least, stop scowling You probably don’t even know you’re doing it. If your resting face doesn’t come across as manically happy, tinge that with some social anxiety and you become one great ball of unapproachable. Normally, I wouldn’t suggest this as a problem that needs fixing, I have personally honed this face to use while travelling alone all the time. However, if you are indeed hoping to meet some useful people and get the most out of this conference, you may need to remind yourself to smile. Prepare some ice breakers This is going to sound stupid, like “no one does this right?” stupid, but, just, trust me a minute. It’s okay to prepare. You don’t need to write word-for-word questions to ask people and practice them in a mirror – that would be strange. I’m suggesting to just have an arsenal of questions to ask people if you get stuck, what session has been your favorite, which ones are you most looking forward to, have you heard X presenter speak before, what did you think of them? Even just thinking about these things in advance can help, and, as a bonus, while the other person is answering it gives you a moment to tamp down that panic, I mean breathe, I mean get to know them. You’re not alone (in the least creepy way possible) See that person in the corner clutching their phone with a mild deer in the headlights look?  That is potentially your new conference buddy. Starting with something along the lines of: I don’t know about you, the sessions here are great but I find the crowds a little tough to deal with. Mind if I park here for a second? is a decent opener. Just walking around and looking at exhibitors (if applicable) is fine, but it’s a little too easy to wander about and not actually speak to anyone if that’s all you’re doing. If joining a group of people talking is too much to start with, one-on-one can be easier. Have goals Are there people in particular you wanted to speak to? Did you have a personal goal of speaking to at least “x” new people? Are you trying to get a contact in a specific company because you want to work with them on something? Does the business have vague goals as well that you may or may not be judged on later? Making specific goals you can accomplish lets you know whether you’ve actually succeeded in your “networking pursuits” or what you need to work on more for next time. Everyone’s got their own coping technique. Some people are able to remind themselves that “humans are fundamentally social creatures” and somehow that helps them, others drink which is not really something I recommend for professional conferences but to each their own, and some focus on the fact that networking can play a big role in their career path. Just do what works for you, and if there’re any tricks you’ve found helpful over the years, please share em.

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  • Anatomy of a .NET Assembly - Signature encodings

    - by Simon Cooper
    If you've just joined this series, I highly recommend you read the previous posts in this series, starting here, or at least these posts, covering the CLR metadata tables. Before we look at custom attribute encoding, we first need to have a brief look at how signatures are encoded in an assembly in general. Signature types There are several types of signatures in an assembly, all of which share a common base representation, and are all stored as binary blobs in the #Blob heap, referenced by an offset from various metadata tables. The types of signatures are: Method definition and method reference signatures. Field signatures Property signatures Method local variables. These are referenced from the StandAloneSig table, which is then referenced by method body headers. Generic type specifications. These represent a particular instantiation of a generic type. Generic method specifications. Similarly, these represent a particular instantiation of a generic method. All these signatures share the same underlying mechanism to represent a type Representing a type All metadata signatures are based around the ELEMENT_TYPE structure. This assigns a number to each 'built-in' type in the framework; for example, Uint16 is 0x07, String is 0x0e, and Object is 0x1c. Byte codes are also used to indicate SzArrays, multi-dimensional arrays, custom types, and generic type and method variables. However, these require some further information. Firstly, custom types (ie not one of the built-in types). These require you to specify the 4-byte TypeDefOrRef coded token after the CLASS (0x12) or VALUETYPE (0x11) element type. This 4-byte value is stored in a compressed format before being written out to disk (for more excruciating details, you can refer to the CLI specification). SzArrays simply have the array item type after the SZARRAY byte (0x1d). Multidimensional arrays follow the ARRAY element type with a series of compressed integers indicating the number of dimensions, and the size and lower bound of each dimension. Generic variables are simply followed by the index of the generic variable they refer to. There are other additions as well, for example, a specific byte value indicates a method parameter passed by reference (BYREF), and other values indicating custom modifiers. Some examples... To demonstrate, here's a few examples and what the resulting blobs in the #Blob heap will look like. Each name in capitals corresponds to a particular byte value in the ELEMENT_TYPE or CALLCONV structure, and coded tokens to custom types are represented by the type name in curly brackets. A simple field: int intField; FIELD I4 A field of an array of a generic type parameter (assuming T is the first generic parameter of the containing type): T[] genArrayField FIELD SZARRAY VAR 0 An instance method signature (note how the number of parameters does not include the return type): instance string MyMethod(MyType, int&, bool[][]); HASTHIS DEFAULT 3 STRING CLASS {MyType} BYREF I4 SZARRAY SZARRAY BOOLEAN A generic type instantiation: MyGenericType<MyType, MyStruct> GENERICINST CLASS {MyGenericType} 2 CLASS {MyType} VALUETYPE {MyStruct} For more complicated examples, in the following C# type declaration: GenericType<T> : GenericBaseType<object[], T, GenericType<T>> { ... } the Extends field of the TypeDef for GenericType will point to a TypeSpec with the following blob: GENERICINST CLASS {GenericBaseType} 3 SZARRAY OBJECT VAR 0 GENERICINST CLASS {GenericType} 1 VAR 0 And a static generic method signature (generic parameters on types are referenced using VAR, generic parameters on methods using MVAR): TResult[] GenericMethod<TInput, TResult>( TInput, System.Converter<TInput, TOutput>); GENERIC 2 2 SZARRAY MVAR 1 MVAR 0 GENERICINST CLASS {System.Converter} 2 MVAR 0 MVAR 1 As you can see, complicated signatures are recursively built up out of quite simple building blocks to represent all the possible variations in a .NET assembly. Now we've looked at the basics of normal method signatures, in my next post I'll look at custom attribute application signatures, and how they are different to normal signatures.

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  • Hype and LINQ

    - by Tony Davis
    "Tired of querying in antiquated SQL?" I blinked in astonishment when I saw this headline on the LinqPad site. Warming to its theme, the site suggests that what we need is to "kiss goodbye to SSMS", and instead use LINQ, a modern query language! Elsewhere, there is an article entitled "Why LINQ beats SQL". The designers of LINQ, along with many DBAs, would, I'm sure, cringe with embarrassment at the suggestion that LINQ and SQL are, in any sense, competitive ways of doing the same thing. In fact what LINQ really is, at last, is an efficient, declarative language for C# and VB programmers to access or manipulate data in objects, local data stores, ORMs, web services, data repositories, and, yes, even relational databases. The fact is that LINQ is essentially declarative programming in a .NET language, and so in many ways encourages developers into a "SQL-like" mindset, even though they are not directly writing SQL. In place of imperative logic and loops, it uses various expressions, operators and declarative logic to build up an "expression tree" describing only what data is required, not the operations to be performed to get it. This expression tree is then parsed by the language compiler, and the result, when used against a relational database, is a SQL string that, while perhaps not always perfect, is often correctly parameterized and certainly no less "optimal" than what is achieved when a developer applies blunt, imperative logic to the SQL language. From a developer standpoint, it is a mistake to consider LINQ simply as a substitute means of querying SQL Server. The strength of LINQ is that that can be used to access any data source, for which a LINQ provider exists. Microsoft supplies built-in providers to access not just SQL Server, but also XML documents, .NET objects, ADO.NET datasets, and Entity Framework elements. LINQ-to-Objects is particularly interesting in that it allows a declarative means to access and manipulate arrays, collections and so on. Furthermore, as Michael Sorens points out in his excellent article on LINQ, there a whole host of third-party LINQ providers, that offers a simple way to get at data in Excel, Google, Flickr and much more, without having to learn a new interface or language. Of course, the need to be generic enough to deal with a range of data sources, from something as mundane as a text file to as esoteric as a relational database, means that LINQ is a compromise and so has inherent limitations. However, it is a powerful and beautifully compact language and one that, at least in its "query syntax" guise, is accessible to developers and DBAs alike. Perhaps there is still hope that LINQ can fulfill Phil Factor's lobster-induced fantasy of a language that will allow us to "treat all data objects, whether Word files, Excel files, XML, relational databases, text files, HTML files, registry files, LDAPs, Outlook and so on, in the same logical way, as linked databases, and extract the metadata, create the entities and relationships in the same way, and use the same SQL syntax to interrogate, create, read, write and update them." Cheers, Tony.

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  • Overload Avoidance

    - by mikef
    A little under a year ago, Matt Simmons wrote a rather reflective article about his terrifying brush with stress-induced ill health. SysAdmins and DBAs have always been prime victims of work-related stress, but I wonder if that predilection is perhaps getting worse, despite the best efforts of Matt and his trusty side-kick, HR. The constant pressure from share-holders and CFOs to 'streamline' the workforce is partially to blame, but the more recent culprit is technology itself. I can't deny that the rise of technologies like virtualization, PowerCLI, PowerShell, and a host of others has been a tremendous boon. As a result, individual IT professionals are now able to handle more and more tasks and manage increasingly large and complex environments. But, without a doubt, this is a two-edged sword; The reward for competence is invariably more work. Unfortunately, SysAdmins play such a pivotal role in modern business that it's easy to see how they can very quickly become swamped in conflicting demands coming from different directions. However, that doesn't justify the ridiculous hours many are asked (or volunteer) to devote to their work. Admirably though their commitment is, it isn't healthy for them, it sets a dangerous expectation, and eventually something will snap. There are times when everyone needs to step up to the plate outside of 'normal' work hours, but that time isn't all the time. Naturally, with all that lovely technology, you can automate more and more of those tricky tasks to keep on top of the workload, but you are still only human. Clever though you may be, there is a very real limit to how far technology can take you. I'm not suggesting that you avoid these technologies, or deliberately aim for mediocrity; I'm just saying that you need to be more than just technically skilled (and Wesley Nonapeptide riffs on and around this topic in his excellent 'Telepathic Robot Drones' blog post). You need to be able to manage expectations, not just Exchange. Specifically, that means your own expectations of what you are capable of, because those come before everyone else's. After all, how can you keep your work-life balance under control, if you're the one setting the bar way too high? Talking to your manager, or discussing issues with your users, is only going to be productive if you have some facts to work with. "Know Thyself" is the first law of managing work overload, and this is obviously a skill which people develop over time; the fact that veteran Sysadmins exist at all is testament to this. I'd just love to know how you get to that point. Personally, I'm using RescueTime to keep myself honest, but I'm open to recommendations for better methods. Do you track your own time, do you have an intuitive sense of what is possible, or do you just rely on someone else to handle that all for you? Cheers, Michael

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  • If unexpected database changes cause you problems – we can help!

    - by Chris Smith
    Have you ever been surprised by an unexpected difference between you database environments? Have you ever found that your Staging database is not the same as your Production database, even though it was the week before? Has an emergency hotfix suddenly appeared in Production over the weekend without your knowledge? Has your client secretly added a couple of indices to their local version of the database to aid performance? Worse still, has a developer ever accidently run a SQL script against the wrong database without noticing their mistake? If you’ve answered “Yes” to any of the above questions then you’ve suffered from ‘drift’. Database drift is where the state of a database (schema, particularly) has moved away from its expected or official state over time. The upshot is that the database is in an unknown or poorly-understood state. Even if these unexpected changes are not destructive, drift can be a big problem when it’s time to release a new version of the database. A deployment to a target database in an unexpected state can error and fail, potentially delaying a vital, time-sensitive update. A big issue with drift is that it can be hard to spot and it can be even harder to determine its provenance. So, before you can deal with an issue caused by drift, you’ll need to know exactly what change has been made, who made it, when they made it and why they made it. Those questions can take a lot of effort to answer. Then you actually need to decide what to do. Do you rollback the change because it was bad? Retrospectively apply it to the Staging environment because it is a required change? Or script the change into version control to get it back in line with your process? Red Gate’s Database Delivery Team have been talking to DBAs, database consultants and database developers to explore the problem of drift. We’ve started to get a really good idea of how big a problem it can be and what database professionals need to know and do, in order to deal with it.  It’s fair to say, we’re pretty excited at the prospect of creating a tool that will really help and we’ve got some great feedback on our initial ideas (see image below).   We’re now well underway with the development of our new drift-spotting product – SQL Lighthouse – and we hope to have a beta release out towards the end of July. What we really need is your help to shape the product into a great tool. So, if database drift is a problem that you’d like help solving and are interested in finding out more about our product, join our mailing list to register your interest in trying out the beta release. Subscribe to our mailing list

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  • What Counts For A DBA: Foresight

    - by drsql
    Of all the valuable attributes of a DBA covered so far in this series, ranging from passion to humility to practicality, perhaps one of the most important attributes may turn out to be the most seemingly-nebulous: foresight. According to Free Dictionary foresight is the "perception of the significance and nature of events before they have occurred". Foresight does not come naturally to most people, as the parent of any teenager will attest. No matter how clearly you see their problems coming they won't listen, and have to fail before eventually (hopefully) learning for themselves. Having graduated from the school of hard knocks, the DBA, the naive teenager no longer, acquires the ability to foretell how events will unfold in response to certain actions or attitudes with the unerring accuracy of a doom-laden prophet. Like Simba in the Lion King, after a few blows to the head, we foretell that a sore head that will be the inevitable consequence of a swing of Rafiki's stick, and we take evasive action. However, foresight is about more than simply learning when to duck. It's about taking the time to understand and prevent the habits that caused the stick to swing in the first place. And based on this definition, I often think there is a lot less foresight on display in my industry than there ought to be. Most DBAs reading this blog will spot a line such as the following in a piece of "working" code, understand immediately why it is less than optimimum, and take evasive action. …WHERE CAST (columnName as int) = 1 However, the programmers who regularly write this sort of code clearly lack that foresight, and this and numerous other examples of similarly-malodorous code prevail throughout our industry (and provide premium-grade fertilizer for the healthy growth of many a consultant's bank account). Sometimes, perhaps harried by impatient managers and painfully tight deadlines, everyone makes mistakes. Yes, I too occasionally write code that "works", but basically stinks. When the problems manifest, it is sometimes accompanied by a sense of grim recognition that somewhere in me existed the foresight to know that that approach would lead to this problem. However, in the headlong rush, warning signs got overlooked, lessons learned previously, which could supply the foresight to the current project, were lost and not applied.   Of course, the problem often is a simple lack of skills, training and knowledge in the relevant technology and/or business space; programmers and DBAs forced to do their best in the face of inadequate training, or to apply their skills in areas where they lack experience. However, often the problem goes deeper than this; I detect in some DBAs and programmers a certain laziness of attitude.   They veer from one project to the next, going with "whatever works", unwilling or unable to take the time to understand where their actions are leading them. Of course, the whole "Agile" mindset is often interpreted to favor flexibility and rapid production over aiming to get things right the first time. The faster you try to travel in the dark, frequently changing direction, the more important it is to have someone who has the foresight to know at least roughly where you are heading. This is doubly true for the data tier which, no matter how you try to deny it, simply cannot be "redone" every month as you learn aspects of the world you are trying to model that, with a little bit of foresight, you would have seen coming.   Sometimes, when as a DBA you can glance briefly at 200 lines of working SQL code and know instinctively why it will cause problems, foresight can feel like magic, but it isn't; it's more like muscle memory. It is acquired as the consequence of good experience, useful communication with those around you, and a willingness to learn continually, through continued education as well as from failure. Foresight can be deployed only by finding time to understand how the lessons learned from other DBAs, and other projects, can help steer the current project in the right direction.   C.S. Lewis once said "The future is something which everyone reaches at the rate of sixty minutes an hour, whatever he does, whoever he is." It cannot be avoided; the quality of what you build now is going to affect you, and others, at some point in the future. Take the time to acquire foresight; it is a love letter to your future self, to say you cared.

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  • Access Denied

    - by Tony Davis
    When Microsoft executives wake up in the night screaming, I suspect they are having a nightmare about their own version of Frankenstein's monster. Created with the best of intentions, without thinking too hard of the long-term strategy, and having long outlived its usefulness, the monster still lives on, occasionally wreaking vengeance on the innocent. Its name is Access; a living synthesis of disparate body parts that is resistant to all attempts at a mercy-killing. In 1986, Microsoft had no database products, and needed one for their new OS/2 operating system, the successor to MSDOS. In 1986, they bought exclusive rights to Sybase DataServer, and were also intent on developing a desktop database to capture Ashton-Tate's dominance of that market, with dbase. This project, first called 'Omega' and later 'Cirrus', eventually spawned two products: Visual Basic in 1991 and Access in late 1992. Whereas Visual Basic battled with PowerBuilder for dominance in the client-server market, Access easily won the desktop database battle, with Dbase III and DataEase falling away. Access did an excellent job of abstracting and simplifying the task of building small database applications in a short amount of time, for a small number of departmental users, and often for a transient requirement. There is an excellent front end and forms generator. We not only see it in Access but parts of it also reappear in SSMS. It's good. A business user can pull together useful reports, without relying on extensive technical support. A skilled Access programmer can deliver a fairly sophisticated application, whilst the traditional client-server programmer is still sharpening his pencil. Even for the SQL Server programmer, the forms generator of Access is useful for sketching out application designs. So far, so good, but here's where the problems start; Access ties together two different products and the backend of Access is the bugbear. The limitations of Jet/ACE are well-known and documented. They range from MDB files that are prone to corruption, especially as they grow in size, pathetic security, and "copy and paste" Backups. The biggest problem though, was an infamous lack of scalability. Because Microsoft never realized how long the product would last, they put little energy into improving the beast. Microsoft 'ate their own dog food' by using Access for Microsoft Exchange and Outlook. They choked on it. For years, scalability and performance problems with Exchange Server have been laid at the door of the Jet Blue engine on which it relies. Substantial development work in Exchange 2010 was required, just in order to improve the engine and storage schema so that it more efficiently handled the reading and writing of mails. The alternative of using SQL Server just never panned out. The Jet engine was designed to limit concurrent users to a small number (10-20). When Access applications outgrew this, bitter experience proved that there really is no easy upgrade path from Access to SQL Server, beyond rewriting the whole lot from scratch. The various initiatives to do this never quite bridged the cultural gulf between Access and a true relational database So, what are the obvious alternatives for small, strategic database applications? I know many users who, for simple 'list maintenance' requirements are very happy using Excel databases. Surely, now that PowerPivot has led the way, it is time for Microsoft to offer a new RAD package for database application development; namely an Excel-based front end for SQL Server Express. In that way, we'll have a powerful and familiar front end, to a scalable database, and a clear upgrade path when an app takes off and needs to go enterprise. Cheers, Tony.

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  • Taking our Friendships to the next level.

    - by RedAndTheCommunity
    Red Gate have been running the Friends of Red Gate program for years now, and over that time we've built some great relationships with some truly awesome members of the SQL and .NET communities. When I took over the running of the program from Annabel in 2011, I was overwhelmed by the enthusiasm and commitment of our Friends. There were just so many of them, however, that it was hard to make the most of the relationships we had with people, and I wanted to fix that. I decided to survey all our Friends, to find out what they wanted to get out of, and put into, being in the Friends of Red Gate (FoRG) program. From the results of that survey, I identified 30 FoRGs that were really willing and able to go that step further to help Red Gate improve their tools, improve their relationship with the community, and improve the Friends of Red Gate program. Those 30 Friends of Red Gate have been awarded 'FoRG+' status. That means they'll: Have a closer relationship with the product teams, by getting involved in projects Have even more access to the inside track about the tools they're interested in Get the opportunity to come visit us at the Red Gate office and really influence the development of the tools. Plus more, depending on how the individual FoRG+ wants to work with us. This doesn't mean I've forgotten our other Friends; I'm working on ways to improve their experience of the Friends of Red Gate program. I'll write about them in another post. If you're an existing Friend of Red Gate, and you're interested in finding out how to get involved in the FoRG+ program, then I'd love to chat to you. For anyone that's interested in joining the Friend of Red Gate program, take a look at the web page dedicated to the program, and get in touch at [email protected] to be put on the waiting list for our 2013 program.

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  • Showplan Operator of the Week - Compute Scalar

    The third part of Fabiano's mission to describe the major Showplan Operators used by SQL Server's Query Optimiser continues with the 'Compute Scalar' operator. Fabiano shows how a tweak to SQL to avoid a 'Compute Scalar' step can improve its performance.

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  • SharePoint Web Part Constructor Fires Twice When Adding it to the Page (and has a different security

    - by Damon
    We had some exciting times debugging an interesting issue with SharePoint 2007 Web Parts.  We had some code in staging that had been running just fine for weeks and had not been touched or changed in about the same amount of time.  However, when we tried to move the web part into a different staging environment, the part started throwing a security exception when we tried to add it to a page.  After a bit of debugging, we determined that the web part was throwing the exception while trying to access the SPGroups property on the SharePoint site.  This was pretty strange because we were logged in as an admin and the code was working perfectly fine before.  During the debugging process, however, we found out that the web part constructor was being fired twice.  On one request, the security context did not seem to have everything it needed in order to run.  On the other request, the security context was populated with the user context with the user making the request (like it normally is).  Moving the security code outside of the constructor seems to have fixed the issue. Why the discrepancy between the two staging environments?  Turns out we deployed the part originally, then deployed an update with the security code.  Since the part was never "added" to the page after the code updates were made (we just deployed a new assembly to make the updates), we never saw the problem.  It seems as though the constructor fires twice when you are adding the web part to the page, and when you run the web part from the web part gallery.  My only thought on why this would occur is that SharePoint is instantiating an instance to get some information from it - which is odd because you would think that would happen with reflection without requiring a new object.  Anyway, the work around is to just not put anything security related inside the constructor, or to do a good job accounting for the possibility of the security context not being present if you are adding the item to the page. Technorati Tags: SharePoint,.NET,Microsoft,ASP.NET

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  • .Net Reflector 6.5 EAP now available

    - by CliveT
    With the release of CLR 4 being so close, we’ve been working hard on getting the new C# and VB language features implemented inside Reflector. The work isn’t complete yet, but we have some of the features working. Most importantly, there are going to be changes to the Reflector object model, and we though it would be useful for people to see the changes and have an opportunity to comment on them. Before going any further, we should tell you what the EAP contains that’s different from the released version. A number of bugs have been fixed, mainly bugs that were raised via the forum. This is slightly offset by the fact that this EAP hasn’t had a whole lot of testing and there may have been new bugs introduced during the development work we’ve been doing. The C# language writer has been changed to display in and out co- and contra-variance markers on interfaces and delegates, and to display default values for optional parameters in method definitions. We also concisely display values passed by reference into COM calls. However, we do not change callsites to display calls using named parameters; this looks like hard work to get right. The forthcoming version of the C# language introduces dynamic types and dynamic calls. The new version of Reflector should display a dynamic call rather than the generated C#: dynamic target = MyTestObject(); target.Hello("Mum"); We have a few bugs in this area where we are not casting to dynamic when necessary. These have been fixed on a branch and should make their way into the next EAP. To support the dynamic features, we’ve added the types IDynamicMethodReferenceExpression, IDynamicPropertyIndexerExpression, and IDynamicPropertyReferenceExpression to the object model. These types, based on the versions without “Dynamic” in the name, reflect the fact that we don’t have full information about the method that is going to be called, but only have its name (as a string). These interfaces are going to change – in an internal version, they have been extended to include information about which parameter positions use runtime types and which use compile time types. There’s also the interface, IDynamicVariableDeclaration, that can be used to determine if a particular variable is used at dynamic call sites as a target. A couple of these language changes have also been added to the Visual Basic language writer. The new features are exposed only when the optimization level is set to .NET 4. When the level is set this high, the other standard language writers will simply display a message to say that they do not handle such an optimization level. Reflector Pro now has 4.0 as an optional compilation target and we have done some work to get the pdb generation right for these new features. The EAP version of Reflector no longer installs the add-in on startup. The first time you run the EAP, it displays the integration options dialog. You can use the checkboxes to select the versions of Visual Studio into which you want to install the EAP version. Note that you can only have one version of Reflector Pro installed in Visual Studio; if you install into a Visual Studio that has another version installed, the previous version will be removed. Please try it out and send your feedback to the EAP forum.

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  • Operator of the Week - Spools, Eager Spool

    For the fifth part of Fabiano's mission to describe the major Showplan Operators used by SQL Server's Query Optimiser, he introduces the spool operators and particularly the Eager Spool, explains blocking and non-blocking and then describes how the Halloween Problem is avoided.

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  • Regional Office Virtualization - Less Can Be More

    The dream of an 'office in a box' has been around for years, but the increasing sophistication of virtualization software has turned the dream into reality. Ben Lye explains the problems and benefits of reducing the amount of physical hardware that were deployed in his organisation's regional offices.

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  • To Serve Man?

    - by Dave Convery
    Since the announcement of Windows 8 and its 'Metro' interface, the .NET community has wondered if the skills they've spent so long developing might be swept aside,in favour of HTML5 and JavaScript. Mercifully, that only seems to be true of SilverLight (as Simon Cooper points out), but it did leave me thinking how easy it is to impose a technology upon people without directly serving their needs. Case in point: QR codes. Once, probably, benign in purpose, they seem to have become a marketer's tool for determining when someone has engaged with an advert in the real world, with the same certainty as is possible online. Nobody really wants to use QR codes - it's far too much hassle. But advertisers want that data - they want to know that someone actually read their billboard / poster / cereal box, and so this flawed technology is suddenly everywhere, providing little to no value to the people who are actually meant to use it. What about 3D cinema? Profits from the film industry have been steadily increasing throughout the period that digital piracy and mass sharing has been possible, yet the industry cinema chains have forced 3D films upon a broadly uninterested audience, as a way of providing more purpose to going to a cinema, rather than watching it at home. Despite advances in digital projection, 3D cinema is scarcely more immersive to us than were William Castle's hoary old tricks of skeletons on wires and buzzing chairs were to our grandparents. iTunes - originally just a piece of software that catalogued and ripped music for you, but which is now multi-purpose bloatware; a massive, system-hogging behemoth. If it was being built for the people that used it, it would have been split into three or more separate pieces of software long ago. But as bloatware, it serves Apple primarily rather than us, stuffed with Music, Video, Various stores and phone / iPad management all bolted into one. Why? It's because, that way, you're more likely to bump into something you want to buy. You can't even buy a new laptop without finding that a significant chunk of your hard drive has been sold to 'select partners' - advertisers, suppliers of virus-busting software, and endless bloatware-flogging pop-ups that make using a new laptop without reformatting the hard drive like stepping back in time. The product you want is not the one you paid for. This is without even looking at services like Facebook and Klout, who provide a notional service with the intention of slurping up as much data about you as possible (in Klout's case, whether you create an account with them or not). What technologies do you find annoying or intrusive, and who benefits from keeping them around?

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  • Why you shouldn't add methods to interfaces in APIs

    - by Simon Cooper
    It is an oft-repeated maxim that you shouldn't add methods to a publically-released interface in an API. Recently, I was hit hard when this wasn't followed. As part of the work on ApplicationMetrics, I've been implementing auto-reporting of MVC action methods; whenever an action was called on a controller, ApplicationMetrics would automatically report it without the developer needing to add manual ReportEvent calls. Fortunately, MVC provides easy hook when a controller is created, letting me log when it happens - the IControllerFactory interface. Now, the dll we provide to instrument an MVC webapp has to be compiled against .NET 3.5 and MVC 1, as the lowest common denominator. This MVC 1 dll will still work when used in an MVC 2, 3 or 4 webapp because all MVC 2+ webapps have a binding redirect redirecting all references to previous versions of System.Web.Mvc to the correct version, and type forwards taking care of any moved types in the new assemblies. Or at least, it should. IControllerFactory In MVC 1 and 2, IControllerFactory was defined as follows: public interface IControllerFactory { IController CreateController(RequestContext requestContext, string controllerName); void ReleaseController(IController controller); } So, to implement the logging controller factory, we simply wrap the existing controller factory: internal sealed class LoggingControllerFactory : IControllerFactory { private readonly IControllerFactory m_CurrentController; public LoggingControllerFactory(IControllerFactory currentController) { m_CurrentController = currentController; } public IController CreateController( RequestContext requestContext, string controllerName) { // log the controller being used FeatureSessionData.ReportEvent("Controller used:", controllerName); return m_CurrentController.CreateController(requestContext, controllerName); } public void ReleaseController(IController controller) { m_CurrentController.ReleaseController(controller); } } Easy. This works as expected in MVC 1 and 2. However, in MVC 3 this type was throwing a TypeLoadException, saying a method wasn't implemented. It turns out that, in MVC 3, the definition of IControllerFactory was changed to this: public interface IControllerFactory { IController CreateController(RequestContext requestContext, string controllerName); SessionStateBehavior GetControllerSessionBehavior( RequestContext requestContext, string controllerName); void ReleaseController(IController controller); } There's a new method in the interface. So when our MVC 1 dll was redirected to reference System.Web.Mvc v3, LoggingControllerFactory tried to implement version 3 of IControllerFactory, was missing the GetControllerSessionBehaviour method, and so couldn't be loaded by the CLR. Implementing the new method Fortunately, there was a workaround. Because interface methods are normally implemented implicitly in the CLR, if we simply declare a virtual method matching the signature of the new method in MVC 3, then it will be ignored in MVC 1 and 2 and implement the extra method in MVC 3: internal sealed class LoggingControllerFactory : IControllerFactory { ... public virtual SessionStateBehaviour GetControllerSessionBehaviour( RequestContext requestContext, string controllerName) {} ... } However, this also has problems - the SessionStateBehaviour type only exists in .NET 4, and we're limited to .NET 3.5 by support for MVC 1 and 2. This means that the only solutions to support all MVC versions are: Construct the LoggingControllerFactory type at runtime using reflection Produce entirely separate dlls for MVC 1&2 and MVC 3. Ugh. And all because of that blasted extra method! Another solution? Fortunately, in this case, there is a third option - System.Web.Mvc also provides a DefaultControllerFactory type that can provide the implementation of GetControllerSessionBehaviour for us in MVC 3, while still allowing us to override CreateController and ReleaseController. However, this does mean that LoggingControllerFactory won't be able to wrap any calls to GetControllerSessionBehaviour. This is an acceptable bug, given the other options, as very few developers will be overriding GetControllerSessionBehaviour in their own custom controller factory. So, if you're providing an interface as part of an API, then please please please don't add methods to it. Especially if you don't provide a 'default' implementing type. Any code compiled against the previous version that can't be updated will have some very tough decisions to make to support both versions.

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