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• Understanding the static keyword

  - by user985482

  I have some experience in developing with Java, Javascript and PHP. I am reading Microsoft Visual C# 2010 Step by Step which I feel it is a very good book on introducing you to the C# language. I seem to be having problems in understanding the static keyword. From what I understand this far if a class is declared static all methods and variable have to be static. The main method always is a static method so in the class that the main method exists all variables and methods are declared static if you have to call them in the main method. Also I have noticed that in order to call a static method from another class you do not need to create an object of that you can use the class name. What are the advantages of declaring static variables and methods? When should I declare static variable and methods?

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• ASP.NET ViewState Tips and Tricks #2

  - by João Angelo

  If you need to store complex types in ViewState DO implement IStateManager to control view state persistence and reduce its size. By default a serializable object will be fully stored in view state using BinaryFormatter. A quick comparison for a complex type with two integers and one string property produces the following results measured using ASP.NET tracing: BinaryFormatter: 328 bytes in view state IStateManager: 28 bytes in view state BinaryFormatter sample code: // DO NOT [Serializable] public class Info { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } } public class ExampleControl : WebControl { protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (!this.Page.IsPostBack) { this.User = new Info { Id = 1, Name = "John Doe", Age = 27 }; } } public Info User { get { object o = this.ViewState["Example_User"]; if (o == null) return null; return (Info)o; } set { this.ViewState["Example_User"] = value; } } } IStateManager sample code: // DO public class Info : IStateManager { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } private bool isTrackingViewState; bool IStateManager.IsTrackingViewState { get { return this.isTrackingViewState; } } void IStateManager.LoadViewState(object state) { var triplet = (Triplet)state; this.Id = (int)triplet.First; this.Name = (string)triplet.Second; this.Age = (int)triplet.Third; } object IStateManager.SaveViewState() { return new Triplet(this.Id, this.Name, this.Age); } void IStateManager.TrackViewState() { this.isTrackingViewState = true; } } public class ExampleControl : WebControl { protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (!this.Page.IsPostBack) { this.User = new Info { Id = 1, Name = "John Doe", Age = 27 }; } } public Info User { get; set; } protected override object SaveViewState() { return new Pair( ((IStateManager)this.User).SaveViewState(), base.SaveViewState()); } protected override void LoadViewState(object savedState) { if (savedState != null) { var pair = (Pair)savedState; this.User = new Info(); ((IStateManager)this.User).LoadViewState(pair.First); base.LoadViewState(pair.Second); } } }

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• Cumulative Updates available for SQL Server 2008 SP2 & SP3

  - by AaronBertrand

  Today Microsoft has released two new cumulative updates for SQL Server 2008. Cumulative Update #10 for SQL Server 2008 Service Pack 2 Knowledge Base Article: KB #2696625 At the time of writing, there is one fix listed The build number is 10.00.4332 Cumulative Update #5 for SQL Server 2008 Service Pack 3 Knowledge Base Article: KB #2696626 At the time of writing, there are four fixes listed The build number is 10.00.5785 As usual, I'll post my standard disclaimer here: these updates are NOT for SQL...(read more)

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• on coding style

  - by user12607414

  I vastly prefer coding to discussing coding style, just as I would prefer to write poetry instead of talking about how it should be written. Sometimes the topic cannot be put off, either because some individual coder is messing up a shared code base and needs to be corrected, or (worse) because some officious soul has decided, "what we really need around here are some strongly enforced style rules!" Neither is the case at the moment, and yet I will venture a post on the subject. The following are not rules, but suggested etiquette. The idea is to allow a coherent style of coding to flourish safely and sanely, as a humane, inductive, social process. Maxim M1: Observe, respect, and imitate the largest-scale precedents available. (Preserve styles of whitespace, capitalization, punctuation, abbreviation, name choice, code block size, factorization, type of comments, class organization, file naming, etc., etc., etc.) Maxim M2: Don't add weight to small-scale variations. (Realize that Maxim M1 has been broken many times, but don't take that as license to create further irregularities.) Maxim M3: Listen to and rely on your reviewers to help you perceive your own coding quirks. (When you review, help the coder do this.) Maxim M4: When you touch some code, try to leave it more readable than you found it. (When you review such changes, thank the coder for the cleanup. When you plan changes, plan for cleanups.) On the Hotspot project, which is almost 1.5 decades old, we have often practiced and benefited from such etiquette. The process is, and should be, inductive, not prescriptive. An ounce of neighborliness is better than a pound of police-work. Reality check: If you actually look at (or live in) the Hotspot code base, you will find we have accumulated many annoying irregularities in our source base. I suppose this is the normal condition of a lived-in space. Unless you want to spend all your time polishing and tidying, you can't live without some smudge and clutter, can you? Final digression: Grammars and dictionaries and other prescriptive rule books are sometimes useful, but we humans learn and maintain our language by example not grammar. The same applies to style rules. Actually, I think the process of maintaining a clean and pleasant working code base is an instance of a community maintaining its common linguistic identity. BTW, I've been reading and listening to John McWhorter lately with great pleasure. (If you end with a digression, is it a tail-digression?)

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• Windows 7 doesn't boot after Ubuntu install

  - by Omu

  I had windows 7 installed on my pc, then I installed Ubuntu 10.10/ During the installation process I have chosen to manually set my partitions: I set a 10GB drive for ubuntu root 1GB drive for swap and for boot drive I've chosen the one used by windows 7 Now I can boot ubuntu, I have the windows 7 option in the boot list, but when I choose Windows 7, it shows me a black screen for a second and returns back to boot screen. Boot Info Script 0.55 dated February 15th, 2010 ============================= Boot Info Summary: ============================== = Windows is installed in the MBR of /dev/sda sda1: _________________________________________________________________________ File system: ntfs Boot sector type: Grub 2 Boot sector info: Grub 2 is installed in the boot sector of sda1 and looks at sector 304908237 of the same hard drive for core.img, but core.img can not be found at this location. No errors found in the Boot Parameter Block. Operating System: Windows 7 Boot files/dirs: /bootmgr /Boot/BCD /Windows/System32/winload.exe sda2: _________________________________________________________________________ File system: ntfs Boot sector type: Windows XP Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files/dirs: sda3: _________________________________________________________________________ File system: Extended Partition Boot sector type: - Boot sector info: sda5: _________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu 10.10 Boot files/dirs: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img sda4: _________________________________________________________________________ File system: swap Boot sector type: - Boot sector info: =========================== Drive/Partition Info: ============================= Drive: sda ___________________ _____________________________________________________ Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start End Size Id System /dev/sda1 * 63 62,894,474 62,894,412 7 HPFS/NTFS /dev/sda2 62,894,478 291,579,749 228,685,272 7 HPFS/NTFS /dev/sda3 291,579,811 309,157,937 17,578,127 5 Extended /dev/sda5 291,579,813 309,157,937 17,578,125 83 Linux /dev/sda4 309,159,936 312,580,095 3,420,160 82 Linux swap / Solaris blkid -c /dev/null: ____________________________________________________________ Device UUID TYPE LABEL /dev/sda1 1266BB2766BB0A8D ntfs /dev/sda2 BEDBF1147C76F703 ntfs DATA /dev/sda3: PTTYPE="dos" /dev/sda4 dd38226d-c7c9-4ae5-a726-6d18d34a22e4 swap /dev/sda5 e1dafd1c-f855-406b-8f9a-f9d527c70255 ext4 /dev/sda: PTTYPE="dos" ============================ "mount | grep ^/dev output: =========================== Device Mount_Point Type Options /dev/sda5 / ext4 (rw,errors=remount-ro,commit=0) =========================== sda5/boot/grub/grub.cfg: =========================== # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga } insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=640x480 load_video insmod gfxterm fi terminal_output gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 set locale_dir=($root)/boot/grub/locale set lang=en insmod gettext if [ "${recordfail}" = 1 ]; then set timeout=-1 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### menuentry 'Ubuntu, with Linux 2.6.35-22-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 linux /boot/vmlinuz-2.6.35-22-generic root=UUID=e1dafd1c-f855-406b-8f9a-f9d527c70255 ro quiet splash initrd /boot/initrd.img-2.6.35-22-generic } menuentry 'Ubuntu, with Linux 2.6.35-22-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 echo 'Loading Linux 2.6.35-22-generic ...' linux /boot/vmlinuz-2.6.35-22-generic root=UUID=e1dafd1c-f855-406b-8f9a-f9d527c70255 ro single echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.35-22-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set e1dafd1c-f855-406b-8f9a-f9d527c70255 linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Windows 7 (loader) (on /dev/sda1)" { insmod part_msdos insmod ntfs set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set 1266bb2766bb0a8d chainloader +1 } ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### =============================== sda5/etc/fstab: =============================== # /etc/fstab: static file system information. # # Use 'blkid -o value -s UUID' to print the universally unique identifier # for a device; this may be used with UUID= as a more robust way to name # devices that works even if disks are added and removed. See fstab(5). # # proc /proc proc nodev,noexec,nosuid 0 0 /dev/sda5 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda4 during installation UUID=dd38226d-c7c9-4ae5-a726-6d18d34a22e4 none swap sw 0 0 =================== sda5: Location of files loaded by Grub: =================== 156.1GB: boot/grub/core.img 156.3GB: boot/grub/grub.cfg 149.9GB: boot/initrd.img-2.6.35-22-generic 156.3GB: boot/vmlinuz-2.6.35-22-generic 149.9GB: initrd.img 156.3GB: vmlinuz

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• Should we exclude code for the code coverage analysis?

  - by romaintaz

  I'm working on several applications, mainly legacy ones. Currently, their code coverage is quite low: generally between 10 and 50%. Since several weeks, we have recurrent discussions with the Bangalore teams (main part of the development is made offshore in India) regarding the exclusions of packages or classes for Cobertura (our code coverage tool, even if we are currently migrating to JaCoCo). Their point of view is the following: as they will not write any unit tests on some layers of the application (1), these layers should be simply excluded from the code coverage measure. In others words, they want to limit the code coverage measure to the code that is tested or should be tested. Also, when they work on unit test for a complex class, the benefits - purely in term of code coverage - will be unnoticed due in a large application. Reducing the scope of the code coverage will make this kind of effort more visible... The interest of this approach is that we will have a code coverage measure that indicates the current status of the part of the application we consider as testable. However, my point of view is that we are somehow faking the figures. This solution is an easy way to reach higher level of code coverage without any effort. Another point that bothers me is the following: if we show a coverage increase from one week to another, how can we tell if this good news is due to the good work of the developers, or simply due to new exclusions? In addition, we will not be able to know exactly what is considered in the code coverage measure. For example, if I have a 10,000 lines of code application with 40% of code coverage, I can deduct that 40% of my code base is tested (2). But what happen if we set exclusions? If the code coverage is now 60%, what can I deduct exactly? That 60% of my "important" code base is tested? How can I As far as I am concerned, I prefer to keep the "real" code coverage value, even if we can't be cheerful about it. In addition, thanks to Sonar, we can easily navigate in our code base and know, for any module / package / class, its own code coverage. But of course, the global code coverage will still be low. What is your opinion on that subject? How do you do on your projects? Thanks. (1) These layers are generally related to the UI / Java beans, etc. (2) I know that's not true. In fact, it only means that 40% of my code base

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• C# Extension Methods - To Extend or Not To Extend...

  - by James Michael Hare

  I've been thinking a lot about extension methods lately, and I must admit I both love them and hate them. They are a lot like sugar, they taste so nice and sweet, but they'll rot your teeth if you eat them too much.   I can't deny that they aren't useful and very handy. One of the major components of the Shared Component library where I work is a set of useful extension methods. But, I also can't deny that they tend to be overused and abused to willy-nilly extend every living type.   So what constitutes a good extension method? Obviously, you can write an extension method for nearly anything whether it is a good idea or not. Many times, in fact, an idea seems like a good extension method but in retrospect really doesn't fit.   So what's the litmus test? To me, an extension method should be like in the movies when a person runs into their twin, separated at birth. You just know you're related. Obviously, that's hard to quantify, so let's try to put a few rules-of-thumb around them.   A good extension method should:     Apply to any possible instance of the type it extends.     Simplify logic and improve readability/maintainability.     Apply to the most specific type or interface applicable.     Be isolated in a namespace so that it does not pollute IntelliSense.     So let's look at a few examples in relation to these rules.   The first rule, to me, is the most important of all. Once again, it bears repeating, a good extension method should apply to all possible instances of the type it extends. It should feel like the long lost relative that should have been included in the original class but somehow was missing from the family tree.    Take this nifty little int extension, I saw this once in a blog and at first I really thought it was pretty cool, but then I started noticing a code smell I couldn't quite put my finger on. So let's look:       public static class IntExtensinos     {         public static int Seconds(int num)         {             return num * 1000;         }           public static int Minutes(int num)         {             return num * 60000;         }     }     This is so you could do things like:       ...     Thread.Sleep(5.Seconds());     ...     proxy.Timeout = 1.Minutes();     ...     Awww, you say, that's cute! Well, that's the problem, it's kitschy and it doesn't always apply (and incidentally you could achieve the same thing with TimeStamp.FromSeconds(5)). It's syntactical candy that looks cool, but tends to rot and pollute the code. It would allow things like:       total += numberOfTodaysOrders.Seconds();     which makes no sense and should never be allowed. The problem is you're applying an extension method to a logical domain, not a type domain. That is, the extension method Seconds() doesn't really apply to ALL ints, it applies to ints that are representative of time that you want to convert to milliseconds.    Do you see what I mean? The two problems, in a nutshell, are that a) Seconds() called off a non-time value makes no sense and b) calling Seconds() off something to pass to something that does not take milliseconds will be off by a factor of 1000 or worse.   Thus, in my mind, you should only ever have an extension method that applies to the whole domain of that type.   For example, this is one of my personal favorites:       public static bool IsBetween<T>(this T value, T low, T high)         where T : IComparable<T>     {         return value.CompareTo(low) >= 0 && value.CompareTo(high) <= 0;     }   This allows you to check if any IComparable<T> is within an upper and lower bound. Think of how many times you type something like:       if (response.Employee.Address.YearsAt >= 2         && response.Employee.Address.YearsAt <= 10)     {     ...     }     Now, you can instead type:       if(response.Employee.Address.YearsAt.IsBetween(2, 10))     {     ...     }     Note that this applies to all IComparable<T> -- that's ints, chars, strings, DateTime, etc -- and does not depend on any logical domain. In addition, it satisfies the second point and actually makes the code more readable and maintainable.   Let's look at the third point. In it we said that an extension method should fit the most specific interface or type possible. Now, I'm not saying if you have something that applies to enumerables, you create an extension for List, Array, Dictionary, etc (though you may have reasons for doing so), but that you should beware of making things TOO general.   For example, let's say we had an extension method like this:       public static T ConvertTo<T>(this object value)     {         return (T)Convert.ChangeType(value, typeof(T));     }         This lets you do more fluent conversions like:       double d = "5.0".ConvertTo<double>();     However, if you dig into Reflector (LOVE that tool) you will see that if the type you are calling on does not implement IConvertible, what you convert to MUST be the exact type or it will throw an InvalidCastException. Now this may or may not be what you want in this situation, and I leave that up to you. Things like this would fail:       object value = new Employee();     ...     // class cast exception because typeof(IEmployee) != typeof(Employee)     IEmployee emp = value.ConvertTo<IEmployee>();       Yes, that's a downfall of working with Convertible in general, but if you wanted your fluent interface to be more type-safe so that ConvertTo were only callable on IConvertibles (and let casting be a manual task), you could easily make it:         public static T ConvertTo<T>(this IConvertible value)     {         return (T)Convert.ChangeType(value, typeof(T));     }         This is what I mean by choosing the best type to extend. Consider that if we used the previous (object) version, every time we typed a dot ('.') on an instance we'd pull up ConvertTo() whether it was applicable or not. By filtering our extension method down to only valid types (those that implement IConvertible) we greatly reduce our IntelliSense pollution and apply a good level of compile-time correctness.   Now my fourth rule is just my general rule-of-thumb. Obviously, you can make extension methods as in-your-face as you want. I included all mine in my work libraries in its own sub-namespace, something akin to:       namespace Shared.Core.Extensions { ... }     This is in a library called Shared.Core, so just referencing the Core library doesn't pollute your IntelliSense, you have to actually do a using on Shared.Core.Extensions to bring the methods in. This is very similar to the way Microsoft puts its extension methods in System.Linq. This way, if you want 'em, you use the appropriate namespace. If you don't want 'em, they won't pollute your namespace.   To really make this work, however, that namespace should only include extension methods and subordinate types those extensions themselves may use. If you plant other useful classes in those namespaces, once a user includes it, they get all the extensions too.   Also, just as a personal preference, extension methods that aren't simply syntactical shortcuts, I like to put in a static utility class and then have extension methods for syntactical candy. For instance, I think it imaginable that any object could be converted to XML:       namespace Shared.Core     {         // A collection of XML Utility classes         public static class XmlUtility         {             ...             // Serialize an object into an xml string             public static string ToXml(object input)             {                 var xs = new XmlSerializer(input.GetType());                   // use new UTF8Encoding here, not Encoding.UTF8. The later includes                 // the BOM which screws up subsequent reads, the former does not.                 using (var memoryStream = new MemoryStream())                 using (var xmlTextWriter = new XmlTextWriter(memoryStream, new UTF8Encoding()))                 {                     xs.Serialize(xmlTextWriter, input);                     return Encoding.UTF8.GetString(memoryStream.ToArray());                 }             }             ...         }     }   I also wanted to be able to call this from an object like:       value.ToXml();     But here's the problem, if i made this an extension method from the start with that one little keyword "this", it would pop into IntelliSense for all objects which could be very polluting. Instead, I put the logic into a utility class so that users have the choice of whether or not they want to use it as just a class and not pollute IntelliSense, then in my extensions namespace, I add the syntactical candy:       namespace Shared.Core.Extensions     {         public static class XmlExtensions         {             public static string ToXml(this object value)             {                 return XmlUtility.ToXml(value);             }         }     }   So now it's the best of both worlds. On one hand, they can use the utility class if they don't want to pollute IntelliSense, and on the other hand they can include the Extensions namespace and use as an extension if they want. The neat thing is it also adheres to the Single Responsibility Principle. The XmlUtility is responsible for converting objects to XML, and the XmlExtensions is responsible for extending object's interface for ToXml().

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• Anatomy of a .NET Assembly - PE Headers

  - by Simon Cooper

  Today, I'll be starting a look at what exactly is inside a .NET assembly - how the metadata and IL is stored, how Windows knows how to load it, and what all those bytes are actually doing. First of all, we need to understand the PE file format. PE files .NET assemblies are built on top of the PE (Portable Executable) file format that is used for all Windows executables and dlls, which itself is built on top of the MSDOS executable file format. The reason for this is that when .NET 1 was released, it wasn't a built-in part of the operating system like it is nowadays. Prior to Windows XP, .NET executables had to load like any other executable, had to execute native code to start the CLR to read & execute the rest of the file. However, starting with Windows XP, the operating system loader knows natively how to deal with .NET assemblies, rendering most of this legacy code & structure unnecessary. It still is part of the spec, and so is part of every .NET assembly. The result of this is that there are a lot of structure values in the assembly that simply aren't meaningful in a .NET assembly, as they refer to features that aren't needed. These are either set to zero or to certain pre-defined values, specified in the CLR spec. There are also several fields that specify the size of other datastructures in the file, which I will generally be glossing over in this initial post. Structure of a PE file Most of a PE file is split up into separate sections; each section stores different types of data. For instance, the .text section stores all the executable code; .rsrc stores unmanaged resources, .debug contains debugging information, and so on. Each section has a section header associated with it; this specifies whether the section is executable, read-only or read/write, whether it can be cached... When an exe or dll is loaded, each section can be mapped into a different location in memory as the OS loader sees fit. In order to reliably address a particular location within a file, most file offsets are specified using a Relative Virtual Address (RVA). This specifies the offset from the start of each section, rather than the offset within the executable file on disk, so the various sections can be moved around in memory without breaking anything. The mapping from RVA to file offset is done using the section headers, which specify the range of RVAs which are valid within that section. For example, if the .rsrc section header specifies that the base RVA is 0x4000, and the section starts at file offset 0xa00, then an RVA of 0x401d (offset 0x1d within the .rsrc section) corresponds to a file offset of 0xa1d. Because each section has its own base RVA, each valid RVA has a one-to-one mapping with a particular file offset. PE headers As I said above, most of the header information isn't relevant to .NET assemblies. To help show what's going on, I've created a diagram identifying all the various parts of the first 512 bytes of a .NET executable assembly. I've highlighted the relevant bytes that I will refer to in this post: Bear in mind that all numbers are stored in the assembly in little-endian format; the hex number 0x0123 will appear as 23 01 in the diagram. The first 64 bytes of every file is the DOS header. This starts with the magic number 'MZ' (0x4D, 0x5A in hex), identifying this file as an executable file of some sort (an .exe or .dll). Most of the rest of this header is zeroed out. The important part of this header is at offset 0x3C - this contains the file offset of the PE signature (0x80). Between the DOS header & PE signature is the DOS stub - this is a stub program that simply prints out 'This program cannot be run in DOS mode.\r\n' to the console. I will be having a closer look at this stub later on. The PE signature starts at offset 0x80, with the magic number 'PE\0\0' (0x50, 0x45, 0x00, 0x00), identifying this file as a PE executable, followed by the PE file header (also known as the COFF header). The relevant field in this header is in the last two bytes, and it specifies whether the file is an executable or a dll; bit 0x2000 is set for a dll. Next up is the PE standard fields, which start with a magic number of 0x010b for x86 and AnyCPU assemblies, and 0x20b for x64 assemblies. Most of the rest of the fields are to do with the CLR loader stub, which I will be covering in a later post. After the PE standard fields comes the NT-specific fields; again, most of these are not relevant for .NET assemblies. The one that is is the highlighted Subsystem field, and specifies if this is a GUI or console app - 0x20 for a GUI app, 0x30 for a console app. Data directories & section headers After the PE and COFF headers come the data directories; each directory specifies the RVA (first 4 bytes) and size (next 4 bytes) of various important parts of the executable. The only relevant ones are the 2nd (Import table), 13th (Import Address table), and 15th (CLI header). The Import and Import Address table are only used by the startup stub, so we will look at those later on. The 15th points to the CLI header, where the CLR-specific metadata begins. After the data directories comes the section headers; one for each section in the file. Each header starts with the section's ASCII name, null-padded to 8 bytes. Again, most of each header is irrelevant, but I've highlighted the base RVA and file offset in each header. In the diagram, you can see the following sections: .text: base RVA 0x2000, file offset 0x200 .rsrc: base RVA 0x4000, file offset 0xa00 .reloc: base RVA 0x6000, file offset 0x1000 The .text section contains all the CLR metadata and code, and so is by far the largest in .NET assemblies. The .rsrc section contains the data you see in the Details page in the right-click file properties page, but is otherwise unused. The .reloc section contains address relocations, which we will look at when we study the CLR startup stub. What about the CLR? As you can see, most of the first 512 bytes of an assembly are largely irrelevant to the CLR, and only a few bytes specify needed things like the bitness (AnyCPU/x86 or x64), whether this is an exe or dll, and the type of app this is. There are some bytes that I haven't covered that affect the layout of the file (eg. the file alignment, which determines where in a file each section can start). These values are pretty much constant in most .NET assemblies, and don't affect the CLR data directly. Conclusion To summarize, the important data in the first 512 bytes of a file is: DOS header. This contains a pointer to the PE signature. DOS stub, which we'll be looking at in a later post. PE signature PE file header (aka COFF header). This specifies whether the file is an exe or a dll. PE standard fields. This specifies whether the file is AnyCPU/32bit or 64bit. PE NT-specific fields. This specifies what type of app this is, if it is an app. Data directories. The 15th entry (at offset 0x168) contains the RVA and size of the CLI header inside the .text section. Section headers. These are used to map between RVA and file offset. The important one is .text, which is where all the CLR data is stored. In my next post, we'll start looking at the metadata used by the CLR directly, which is all inside the .text section.

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• Andengine put bullet to pull, when it leaves screen

  - by Ashot

  i'm creating a bullet with physics body. Bullet class (extends Sprite class) has die() method, which unregister physics connector, hide sprite and put it in pull public void die() { Log.d("bulletDie", "See you in hell!"); if (this.isVisible()) { this.setVisible(false); mPhysicsWorld.unregisterPhysicsConnector(physicsConnector); physicsConnector.setUpdatePosition(false); body.setActive(false); this.setIgnoreUpdate(true); bulletsPool.recyclePoolItem(this); } } in onUpdate method of PhysicsConnector i executes die method, when sprite leaves screen physicsConnector = new PhysicsConnector(this,body,true,false) { @Override public void onUpdate(final float pSecondsElapsed) { super.onUpdate(pSecondsElapsed); if (!camera.isRectangularShapeVisible(_bullet)) { Log.d("bulletDie","Dead?"); _bullet.die(); } } }; it works as i expected, but _bullet.die() executes TWICE. what i`m doing wrong and is it right way to hide sprites? here is full code of Bullet class (it is inner class of class that represents player) private class Bullet extends Sprite implements PhysicsConstants { private final Body body; private final PhysicsConnector physicsConnector; private final Bullet _bullet; private int id; public Bullet(float x, float y, ITextureRegion texture, VertexBufferObjectManager vertexBufferObjectManager) { super(x,y,texture,vertexBufferObjectManager); _bullet = this; id = bulletId++; body = PhysicsFactory.createCircleBody(mPhysicsWorld, this, BodyDef.BodyType.DynamicBody, bulletFixture); physicsConnector = new PhysicsConnector(this,body,true,false) { @Override public void onUpdate(final float pSecondsElapsed) { super.onUpdate(pSecondsElapsed); if (!camera.isRectangularShapeVisible(_bullet)) { Log.d("bulletDie","Dead?"); Log.d("bulletDie",id+""); _bullet.die(); } } }; mPhysicsWorld.registerPhysicsConnector(physicsConnector); $this.getParent().attachChild(this); } public void reset() { final float angle = canon.getRotation(); final float x = (float) ((Math.cos(MathUtils.degToRad(angle))*radius) + centerX) / PIXEL_TO_METER_RATIO_DEFAULT; final float y = (float) ((Math.sin(MathUtils.degToRad(angle))*radius) + centerY) / PIXEL_TO_METER_RATIO_DEFAULT; this.setVisible(true); this.setIgnoreUpdate(false); body.setActive(true); mPhysicsWorld.registerPhysicsConnector(physicsConnector); body.setTransform(new Vector2(x,y),0); } public Body getBody() { return body; } public void setLinearVelocity(Vector2 velocity) { body.setLinearVelocity(velocity); } public void die() { Log.d("bulletDie", "See you in hell!"); if (this.isVisible()) { this.setVisible(false); mPhysicsWorld.unregisterPhysicsConnector(physicsConnector); physicsConnector.setUpdatePosition(false); body.setActive(false); this.setIgnoreUpdate(true); bulletsPool.recyclePoolItem(this); } } }

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• Cumulative Updates available for SQL Server 2008 SP2 & SP3

  - by AaronBertrand

  Today Microsoft has released two new cumulative updates for SQL Server 2008. Cumulative Update #10 for SQL Server 2008 Service Pack 2 Knowledge Base Article: KB #2696625 At the time of writing, there is one fix listed The build number is 10.00.4332 Cumulative Update #5 for SQL Server 2008 Service Pack 3 Knowledge Base Article: KB #2696626 At the time of writing, there are four fixes listed The build number is 10.00.5785 As usual, I'll post my standard disclaimer here: these updates are NOT for SQL...(read more)

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• Polynomial.Net

  Polynomial Class Library - An easy way to working with polynomials

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• Detecting HTML5/CSS3 Features using Modernizr

  - by dwahlin

  HTML5, CSS3, and related technologies such as canvas and web sockets bring a lot of useful new features to the table that can take Web applications to the next level. These new technologies allow applications to be built using only HTML, CSS, and JavaScript allowing them to be viewed on a variety of form factors including tablets and phones. Although HTML5 features offer a lot of promise, it’s not realistic to develop applications using the latest technologies without worrying about supporting older browsers in the process. If history has taught us anything it’s that old browsers stick around for years and years which means developers have to deal with backward compatibility issues. This is especially true when deploying applications to the Internet that target the general public. This begs the question, “How do you move forward with HTML5 and CSS3 technologies while gracefully handling unsupported features in older browsers?” Although you can write code by hand to detect different HTML5 and CSS3 features, it’s not always straightforward. For example, to check for canvas support you need to write code similar to the following:   <script> window.onload = function () { if (canvasSupported()) { alert('canvas supported'); } }; function canvasSupported() { var canvas = document.createElement('canvas'); return (canvas.getContext && canvas.getContext('2d')); } </script> If you want to check for local storage support the following check can be made. It’s more involved than it should be due to a bug in older versions of Firefox. <script> window.onload = function () { if (localStorageSupported()) { alert('local storage supported'); } }; function localStorageSupported() { try { return ('localStorage' in window && window['localStorage'] != null); } catch(e) {} return false; } </script> Looking through the previous examples you can see that there’s more than meets the eye when it comes to checking browsers for HTML5 and CSS3 features. It takes a lot of work to test every possible scenario and every version of a given browser. Fortunately, you don’t have to resort to writing custom code to test what HTML5/CSS3 features a given browser supports. By using a script library called Modernizr you can add checks for different HTML5/CSS3 features into your pages with a minimal amount of code on your part. Let’s take a look at some of the key features Modernizr offers.   Getting Started with Modernizr The first time I heard the name “Modernizr” I thought it “modernized” older browsers by added missing functionality. In reality, Modernizr doesn’t actually handle adding missing features or “modernizing” older browsers. The Modernizr website states, “The name Modernizr actually stems from the goal of modernizing our development practices (and ourselves)”. Because it relies on feature detection rather than browser sniffing (a common technique used in the past – that never worked that great), Modernizr definitely provides a more modern way to test features that a browser supports and can even handle loading additional scripts called shims or polyfills that fill in holes that older browsers may have. It’s a great tool to have in your arsenal if you’re a web developer. Modernizr is available at http://modernizr.com. Two different types of scripts are available including a development script and custom production script. To generate a production script, the site provides a custom script generation tool rather than providing a single script that has everything under the sun for HTML5/CSS3 feature detection. Using the script generation tool you can pick the specific test functionality that you need and ignore everything that you don’t need. That way the script is kept as small as possible. An example of the custom script download screen is shown next. Notice that specific CSS3, HTML5, and related feature tests can be selected. Once you’ve downloaded your custom script you can add it into your web page using the standard <script> element and you’re ready to start using Modernizr. <script src="Scripts/Modernizr.js" type="text/javascript"></script>   Modernizr and the HTML Element Once you’ve add a script reference to Modernizr in a page it’ll go to work for you immediately. In fact, by adding the script several different CSS classes will be added to the page’s <html> element at runtime. These classes define what features the browser supports and what features it doesn’t support. Features that aren’t supported get a class name of “no-FeatureName”, for example “no-flexbox”. Features that are supported get a CSS class name based on the feature such as “canvas” or “websockets”. An example of classes added when running a page in Chrome is shown next:   <html class=" js flexbox canvas canvastext webgl no-touch geolocation postmessage websqldatabase indexeddb hashchange history draganddrop websockets rgba hsla multiplebgs backgroundsize borderimage borderradius boxshadow textshadow opacity cssanimations csscolumns cssgradients cssreflections csstransforms csstransforms3d csstransitions fontface generatedcontent video audio localstorage sessionstorage webworkers applicationcache svg inlinesvg smil svgclippaths"> Here’s an example of what the <html> element looks like at runtime with Internet Explorer 9:   <html class=" js no-flexbox canvas canvastext no-webgl no-touch geolocation postmessage no-websqldatabase no-indexeddb hashchange no-history draganddrop no-websockets rgba hsla multiplebgs backgroundsize no-borderimage borderradius boxshadow no-textshadow opacity no-cssanimations no-csscolumns no-cssgradients no-cssreflections csstransforms no-csstransforms3d no-csstransitions fontface generatedcontent video audio localstorage sessionstorage no-webworkers no-applicationcache svg inlinesvg smil svgclippaths">   When using Modernizr it’s a common practice to define an <html> element in your page with a no-js class added as shown next:   <html class="no-js">   You’ll see starter projects such as HTML5 Boilerplate (http://html5boilerplate.com) or Initializr (http://initializr.com) follow this approach (see my previous post for more information on HTML5 Boilerplate). By adding the no-js class it’s easy to tell if a browser has JavaScript enabled or not. If JavaScript is disabled then no-js will stay on the <html> element. If JavaScript is enabled, no-js will be removed by Modernizr and a js class will be added along with other classes that define supported/unsupported features. Working with HTML5 and CSS3 Features You can use the CSS classes added to the <html> element directly in your CSS files to determine what style properties to use based upon the features supported by a given browser. For example, the following CSS can be used to render a box shadow for browsers that support that feature and a simple border for browsers that don’t support the feature: .boxshadow #MyContainer { border: none; -webkit-box-shadow: #666 1px 1px 1px; -moz-box-shadow: #666 1px 1px 1px; } .no-boxshadow #MyContainer { border: 2px solid black; }   If a browser supports box-shadows the boxshadow CSS class will be added to the <html> element by Modernizr. It can then be associated with a given element. This example associates the boxshadow class with a div with an id of MyContainer. If the browser doesn’t support box shadows then the no-boxshadow class will be added to the <html> element and it can be used to render a standard border around the div. This provides a great way to leverage new CSS3 features in supported browsers while providing a graceful fallback for older browsers. In addition to using the CSS classes that Modernizr provides on the <html> element, you also use a global Modernizr object that’s created. This object exposes different properties that can be used to detect the availability of specific HTML5 or CSS3 features. For example, the following code can be used to detect canvas and local storage support. You can see that the code is much simpler than the code shown at the beginning of this post. It also has the added benefit of being tested by a large community of web developers around the world running a variety of browsers.   $(document).ready(function () { if (Modernizr.canvas) { //Add canvas code } if (Modernizr.localstorage) { //Add local storage code } }); The global Modernizr object can also be used to test for the presence of CSS3 features. The following code shows how to test support for border-radius and CSS transforms:   $(document).ready(function () { if (Modernizr.borderradius) { $('#MyDiv').addClass('borderRadiusStyle'); } if (Modernizr.csstransforms) { $('#MyDiv').addClass('transformsStyle'); } });   Several other CSS3 feature tests can be performed such as support for opacity, rgba, text-shadow, CSS animations, CSS transitions, multiple backgrounds, and more. A complete list of supported HTML5 and CSS3 tests that Modernizr supports can be found at http://www.modernizr.com/docs.   Loading Scripts using Modernizr In cases where a browser doesn’t support a specific feature you can either provide a graceful fallback or load a shim/polyfill script to fill in missing functionality where appropriate (more information about shims/polyfills can be found at https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills). Modernizr has a built-in script loader that can be used to test for a feature and then load a script if the feature isn’t available. The script loader is built-into Modernizr and is also available as a standalone yepnope script (http://yepnopejs.com). It’s extremely easy to get started using the script loader and it can really simplify the process of loading scripts based on the availability of a particular browser feature. To load scripts dynamically you can use Modernizr’s load() function which accepts properties defining the feature to test (test property), the script to load if the test succeeds (yep property), the script to load if the test fails (nope property), and a script to load regardless of if the test succeeds or fails (both property). An example of using load() with these properties is show next: Modernizr.load({ test: Modernizr.canvas, yep: 'html5CanvasAvailable.js’, nope: 'excanvas.js’, both: 'myCustomScript.js' }); In this example Modernizr is used to not only load scripts but also to test for the presence of the canvas feature. If the target browser supports the HTML5 canvas then the html5CanvasAvailable.js script will be loaded along with the myCustomScript.js script (use of the yep property in this example is a bit contrived – it was added simply to demonstrate how the property can be used in the load() function). Otherwise, a polyfill script named excanvas.js will be loaded to add missing canvas functionality for Internet Explorer versions prior to 9. Once excanvas.js is loaded the myCustomScript.js script will be loaded. Because Modernizr handles loading scripts, you can also use it in creative ways. For example, you can use it to load local scripts when a 3rd party Content Delivery Network (CDN) such as one provided by Google or Microsoft is unavailable for whatever reason. The Modernizr documentation provides the following example that demonstrates the process for providing a local fallback for jQuery when a CDN is down:   Modernizr.load([ { load: '//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.js', complete: function () { if (!window.jQuery) { Modernizr.load('js/libs/jquery-1.6.4.min.js'); } } }, { // This will wait for the fallback to load and // execute if it needs to. load: 'needs-jQuery.js' } ]); This code attempts to load jQuery from the Google CDN first. Once the script is downloaded (or if it fails) the function associated with complete will be called. The function checks to make sure that the jQuery object is available and if it’s not Modernizr is used to load a local jQuery script. After all of that occurs a script named needs-jQuery.js will be loaded. Conclusion If you’re building applications that use some of the latest and greatest features available in HTML5 and CSS3 then Modernizr is an essential tool. By using it you can reduce the amount of custom code required to test for browser features and provide graceful fallbacks or even load shim/polyfill scripts for older browsers to help fill in missing functionality. 

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• Using Sitecore RenderingContext Parameters as MVC controller action arguments

  - by Kyle Burns

  I have been working with the Technical Preview of Sitecore 6.6 on a project and have been for the most part happy with the way that Sitecore (which truly is an MVC implementation unto itself) has been expanded to support ASP.NET MVC. That said, getting up to speed with the combined platform has not been entirely without stumbles and today I want to share one area where Sitecore could have really made things shine from the "it just works" perspective. A couple days ago I was asked by a colleague about the usage of the "Parameters" field that is defined on Sitecore's Controller Rendering data template. Based on the standard way that Sitecore handles a field named Parameters, I was able to deduce that the field expected key/value pairs separated by the "&" character, but beyond that I wasn't sure and didn't see anything from a documentation perspective to guide me, so it was time to dig and find out where the data in the field was made available. My first thought was that it would be really nice if Sitecore handled the parameters in this field consistently with the way that ASP.NET MVC handles the various parameter collections on the HttpRequest object and automatically maps them to parameters of the action method executing. Being the hopeful sort, I configured a name/value pair on one of my renderings, added a parameter with matching name to the controller action and fired up the bugger to see... that the parameter was not populated. Having established that the field's value was not going to be presented to me the way that I had hoped it would, the next assumption that I would work on was that Sitecore would handle this field similar to how they handle other similar data and would plug it into some ambient object that I could reference from within the controller method. After a considerable amount of guessing, testing, and cracking code open with Redgate's Reflector (a must-have companion to Sitecore documentation), I found that the most direct way to access the parameter was through the ambient RenderingContext object using code similar to: string myArgument = string.Empty; var rc = Sitecore.Mvc.Presentation.RenderingContext.CurrentOrNull; if (rc != null) {     var parms = rc.Rendering.Parameters;     myArgument = parms["myArgument"]; } At this point, we know how this field is used out of the box from Sitecore and can provide information from Sitecore's Content Editor that will be available when the controller action is executing, but it feels a little dirty. In order to properly test the action method I would have to do a lot of setup work and possible use an isolation framework such as Pex and Moles to get at a value that my action method is dependent upon. Notice I said that my method is dependent upon the value but in order to meet that dependency I've accepted another dependency upon Sitecore's RenderingContext.  I'm a big believer in, when possible, ensuring that any piece of code explicitly advertises dependencies using the method signature, so I found myself still wanting this to work the same as if the parameters were in the request route, querystring, or form by being able to add a myArgument parameter to the action method and have this parameter populated by the framework. Lucky for us, the ASP.NET MVC framework is extremely flexible and provides some easy to grok and use extensibility points. ASP.NET MVC is able to provide information from the request as input parameters to controller actions because it uses objects which implement an interface called IValueProvider and have been registered to service the application. The most basic statement of responsibility for an IValueProvider implementation is "I know about some data which is indexed by key. If you hand me the key for a piece of data that I know about I give you that data". When preparing to invoke a controller action, the framework queries registered IValueProvider implementations with the name of each method argument to see if the ValueProvider can supply a value for the parameter. (the rest of this post will assume you're working along and make a lot more sense if you do) Let's pull Sitecore out of the equation for a second to simplify things and create an extremely simple IValueProvider implementation. For this example, I first create a new ASP.NET MVC3 project in Visual Studio, selecting "Internet Application" and otherwise taking defaults (I'm assuming that anyone reading this far in the post either already knows how to do this or will need to take a quick run through one of the many available basic MVC tutorials such as the MVC Music Store). Once the new project is created, go to the Index action of HomeController.  This action sets a Message property on the ViewBag to "Welcome to ASP.NET MVC!" and invokes the View, which has been coded to display the Message. For our example, we will remove the hard coded message from this controller (although we'll leave it just as hard coded somewhere else - this is sample code). For the first step in our exercise, add a string parameter to the Index action method called welcomeMessage and use the value of this argument to set the ViewBag.Message property. The updated Index action should look like: public ActionResult Index(string welcomeMessage) {     ViewBag.Message = welcomeMessage;     return View(); } This represents the entirety of the change that you will make to either the controller or view.  If you run the application now, the home page will display and no message will be presented to the user because no value was supplied to the Action method. Let's now write a ValueProvider to ensure this parameter gets populated. We'll start by creating a new class called StaticValueProvider. When the class is created, we'll update the using statements to ensure that they include the following: using System.Collections.Specialized; using System.Globalization; using System.Web.Mvc; With the appropriate using statements in place, we'll update the StaticValueProvider class to implement the IValueProvider interface. The System.Web.Mvc library already contains a pretty flexible dictionary-like implementation called NameValueCollectionValueProvider, so we'll just wrap that and let it do most of the real work for us. The completed class looks like: public class StaticValueProvider : IValueProvider {     private NameValueCollectionValueProvider _wrappedProvider;     public StaticValueProvider(ControllerContext controllerContext)     {         var parameters = new NameValueCollection();         parameters.Add("welcomeMessage", "Hello from the value provider!");         _wrappedProvider = new NameValueCollectionValueProvider(parameters, CultureInfo.InvariantCulture);     }     public bool ContainsPrefix(string prefix)     {         return _wrappedProvider.ContainsPrefix(prefix);     }     public ValueProviderResult GetValue(string key)     {         return _wrappedProvider.GetValue(key);     } } Notice that the only entry in the collection matches the name of the argument to our HomeController's Index action.  This is the important "secret sauce" that will make things work. We've got our new value provider now, but that's not quite enough to be finished. Mvc obtains IValueProvider instances using factories that are registered when the application starts up. These factories extend the abstract ValueProviderFactory class by initializing and returning the appropriate implementation of IValueProvider from the GetValueProvider method. While I wouldn't do so in production code, for the sake of this example, I'm going to add the following class definition within the StaticValueProvider.cs source file: public class StaticValueProviderFactory : ValueProviderFactory {     public override IValueProvider GetValueProvider(ControllerContext controllerContext)     {         return new StaticValueProvider(controllerContext);     } } Now that we have a factory, we can register it by adding the following line to the end of the Application_Start method in Global.asax.cs: ValueProviderFactories.Factories.Add(new StaticValueProviderFactory()); If you've done everything right to this point, you should be able to run the application and be presented with the home page reading "Hello from the value provider!". Now that you have the basics of the IValueProvider down, you have everything you need to enhance your Sitecore MVC implementation by adding an IValueProvider that exposes values from the ambient RenderingContext's Parameters property. I'll provide the code for the IValueProvider implementation (which should look VERY familiar) and you can use the work we've already done as a reference to create and register the factory: public class RenderingContextValueProvider : IValueProvider {     private NameValueCollectionValueProvider _wrappedProvider = null;     public RenderingContextValueProvider(ControllerContext controllerContext)     {         var collection = new NameValueCollection();         var rc = RenderingContext.CurrentOrNull;         if (rc != null && rc.Rendering != null)         {             foreach(var parameter in rc.Rendering.Parameters)             {                 collection.Add(parameter.Key, parameter.Value);             }         }         _wrappedProvider = new NameValueCollectionValueProvider(collection, CultureInfo.InvariantCulture);         }     public bool ContainsPrefix(string prefix)     {         return _wrappedProvider.ContainsPrefix(prefix);     }     public ValueProviderResult GetValue(string key)     {         return _wrappedProvider.GetValue(key);     } } In this post I've discussed the MVC IValueProvider used to map data to controller action method arguments and how this can be integrated into your Sitecore 6.6 MVC solution.

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• Xen 4.0.1 on Ubuntu 10.10 not booting

  - by Disco

  I'm trying to get Xen 4.0.1 run as dom0 on a fresh/clean install of 10.10 desktop (x64). Followed the step by step tutorial at http://wiki.xensource.com/xenwiki/Xen4.0 I have the pvops kernel in /boot, also included the ext4 fs support by recompiling the kernel by : make -j6 linux-2.6-pvops-config CONFIGMODE=menuconfig make -j6 linux-2.6-pvops-build make -j6 linux-2.6-pvops-install Here's my grub entry : menuentry 'Xen4' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod part_msdos insmod ext2 insmod ext3 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set 2bf3177a-92fd-4196-901a-da8d810b04b4 multiboot /xen-4.0.gz dom0_mem=1024M loglvl=all guest_loglvl=all module /vmlinuz-2.6.32.27 root=UUID=2bf3177a-92fd-4196-901a-da8d810b04b4 ro module /initrd.img-2.6.32.27 } blkid /dev/sda1 gives the : /dev/sda1: UUID="2bf3177a-92fd-4196-901a-da8d810b04b4" TYPE="ext3" My partition shemes is : /boot (ext3) / (ext4) Whatever option i've tried i end up with : mounting none on /dev failed: no such file or directory And message complaining that it cannot find the device with uuid ... It's taking my hairs out, if somone has a clue ...

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• WebSocket Samples in GlassFish 4 build 66 - javax.websocket.* package: TOTD #190

  - by arungupta

  This blog has published a few blogs on using JSR 356 Reference Implementation (Tyrus) integrated in GlassFish 4 promoted builds. TOTD #183: Getting Started with WebSocket in GlassFish TOTD #184: Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark TOTD #185: Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket TOTD #186: Custom Text and Binary Payloads using WebSocket TOTD #189: Collaborative Whiteboard using WebSocket in GlassFish 4 The earlier blogs created a WebSocket endpoint as: import javax.net.websocket.annotations.WebSocketEndpoint;@WebSocketEndpoint("websocket")public class MyEndpoint { . . . Based upon the discussion in JSR 356 EG, the package names have changed to javax.websocket.*. So the updated endpoint definition will look like: import javax.websocket.WebSocketEndpoint;@WebSocketEndpoint("websocket")public class MyEndpoint { . . . The POM dependency is: <dependency> <groupId>javax.websocket</groupId> <artifactId>javax.websocket-api</artifactId> <version>1.0-b09</version> </dependency> And if you are using GlassFish 4 build 66, then you also need to provide a dummy EndpointFactory implementation as: import javax.websocket.WebSocketEndpoint;@WebSocketEndpoint(value="websocket", factory=MyEndpoint.DummyEndpointFactory.class)public class MyEndpoint { . . .   class DummyEndpointFactory implements EndpointFactory {    @Override public Object createEndpoint() { return null; }  }} This is only interim and will be cleaned up in subsequent builds. But I've seen couple of complaints about this already and so this deserves a short blog. Have you been tracking the latest Java EE 7 implementations in GlassFish 4 promoted builds ?

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• Improvements to Joshua Bloch's Builder Design Pattern?

  - by Jason Fotinatos

  Back in 2007, I read an article about Joshua Blochs take on the "builder pattern" and how it could be modified to improve the overuse of constructors and setters, especially when an object has a large number of properties, most of which are optional. A brief summary of this design pattern is articled here [http://rwhansen.blogspot.com/2007/07/theres-builder-pattern-that-joshua.html]. I liked the idea, and have been using it since. The problem with it, while it is very clean and nice to use from the client perspective, implementing it can be a pain in the bum! There are so many different places in the object where a single property is reference, and thus creating the object, and adding a new property takes a lot of time. So...I had an idea. First, an example object in Joshua Bloch's style: Josh Bloch Style: public class OptionsJoshBlochStyle { private final String option1; private final int option2; // ...other options here <<<< public String getOption1() { return option1; } public int getOption2() { return option2; } public static class Builder { private String option1; private int option2; // other options here <<<<< public Builder option1(String option1) { this.option1 = option1; return this; } public Builder option2(int option2) { this.option2 = option2; return this; } public OptionsJoshBlochStyle build() { return new OptionsJoshBlochStyle(this); } } private OptionsJoshBlochStyle(Builder builder) { this.option1 = builder.option1; this.option2 = builder.option2; // other options here <<<<<< } public static void main(String[] args) { OptionsJoshBlochStyle optionsVariation1 = new OptionsJoshBlochStyle.Builder().option1("firefox").option2(1).build(); OptionsJoshBlochStyle optionsVariation2 = new OptionsJoshBlochStyle.Builder().option1("chrome").option2(2).build(); } } Now my "improved" version: public class Options { // note that these are not final private String option1; private int option2; // ...other options here public String getOption1() { return option1; } public int getOption2() { return option2; } public static class Builder { private final Options options = new Options(); public Builder option1(String option1) { this.options.option1 = option1; return this; } public Builder option2(int option2) { this.options.option2 = option2; return this; } public Options build() { return options; } } private Options() { } public static void main(String[] args) { Options optionsVariation1 = new Options.Builder().option1("firefox").option2(1).build(); Options optionsVariation2 = new Options.Builder().option1("chrome").option2(2).build(); } } As you can see in my "improved version", there are 2 less places in which we need to add code about any addition properties (or options, in this case)! The only negative that I can see is that the instance variables of the outer class are not able to be final. But, the class is still immutable without this. Is there really any downside to this improvement in maintainability? There has to be a reason which he repeated the properties within the nested class that I'm not seeing?

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• Hiding the Flash Message After a Time Delay

  - by Madhan ayyasamy

  Hi Friends,The flash hash is a great way to provide feedback to your users.Here is a quick tip for hiding the flash message after a period of time if you don’t want to leave it lingering around.First, add this line to the head of your layout to ensure the prototype and script.aculo.us javascript libraries are loaded:Next, add the following to either your layout (recommended), your view templates or a partial depending on your needs. I usually add this to a partial and include the partial in my layouts. "flash", :id = flash_type % "text/javascript" do % setTimeout("new Effect.Fade('');", 10000); This will wrap the flash message in a div with class=‘flash’ and id=‘error’, ‘notice’ or ‘warn’ depending on the flash key specified.The value ‘10000’ is the time in milliseconds before the flash will disappear. In this case, 10 seconds.This function looks pretty good and little javascript stunts like this can help make your site feel more professional. It’s also worth bearing in mind though, not everybody can see well or read as quickly as others so this may not be suitable for every application.Update:As Mitchell has pointed out (see comments below), it may be better to set the flash_type as the div class rather than it’s id. If there is the possibility that you’ll be showing more than one flash message per page, setting the flash_type as the div id will result in your HTML/XHTML code becoming invalid because the unique intentifier will be used more than once per page.Here is a slightly more complex version of the method shown above that will hide all divs with class ‘flash’ after a time delay, achieving the same effect and also ensuring your code stays valid with more than one flash message! "flash #{flash_type}" % "text/javascript" do % setTimeout("$$('div.flash').each(function(flash){ flash.hide();})", 10000); In this example, the div id is not set at all. Instead, each flash div will have class “div” and also class of the type of flash message (“error”, “warning” etc.).Have a Great Day..:)

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• How best to handle ID3D11InputLayout in rendering code?

  - by JohnB

  I'm looking for an elegant way to handle input layouts in my directx11 code. The problem I have that I have an Effect class and a Element class. The effect class encapsulates shaders and similar settings, and the Element class contains something that can be drawn (3d model, lanscape etc) My drawing code sets the device shaders etc using the effect specified and then calls the draw function of the Element to draw the actual geometry contained in it. The problem is this - I need to create an D3D11InputLayout somewhere. This really belongs in the Element class as it's no business of the rest of the system how that element chooses to represent it's vertex layout. But in order to create the object the API requires the vertex shader bytecode for the vertex shader that will be used to draw the object. In directx9 it was easy, there was no dependency so my element could contain it's own input layout structures and set them without the effect being involved. But the Element shouldn't really have to know anything about the effect that it's being drawn with, that's just render settings, and the Element is there to provide geometry. So I don't really know where to store and how to select the InputLayout for each draw call. I mean, I've made something work but it seems very ugly. This makes me thing I've either missed something obvious, or else my design of having all the render settings in an Effect, the Geometry in an Element, and a 3rd party that draws it all is just flawed. Just wondering how anyone else handles their input layouts in directx11 in a elegant way?

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• Ubuntu 10.04 not detecting multiple monitors

  - by user28837

  I have 2 graphics cards, the output from the lspci: 01:00.0 VGA compatible controller: ATI Technologies Inc RV770 [Radeon HD 4850] 02:00.0 VGA compatible controller: ATI Technologies Inc RV710 [Radeon HD 4350] I have one monitor connected to the 4850 and 2 connected to the 4350. However when I go into System Preferences Monitors the only monitor shown is the one connected to the 4850. Is there something I need to enable for it to be able to use the other card? How do I get this to work. Thanks. As per request: X.Org X Server 1.7.6 Release Date: 2010-03-17 X Protocol Version 11, Revision 0 Build Operating System: Linux 2.6.24-25-server i686 Ubuntu Current Operating System: Linux jeff-desktop 2.6.32-22-generic-pae #33-Ubuntu SMP Wed Apr 28 14:57:29 UTC 2010 i686 Kernel command line: BOOT_IMAGE=/boot/vmlinuz-2.6.32-22-generic-pae root=UUID=852e1013-4ed6-40fd-a462-c29087888383 ro quiet splash Build Date: 23 April 2010 05:11:50PM xorg-server 2:1.7.6-2ubuntu7 (Bryce Harrington <[email protected]>) Current version of pixman: 0.16.4 Before reporting problems, check http://wiki.x.org to make sure that you have the latest version. Markers: (--) probed, (**) from config file, (==) default setting, (++) from command line, (!!) notice, (II) informational, (WW) warning, (EE) error, (NI) not implemented, (??) unknown. (==) Log file: "/var/log/Xorg.0.log", Time: Tue May 11 08:24:52 2010 (==) Using config file: "/etc/X11/xorg.conf" (==) Using config directory: "/usr/lib/X11/xorg.conf.d" (==) No Layout section. Using the first Screen section. (**) |-->Screen "Default Screen" (0) (**) | |-->Monitor "<default monitor>" (==) No device specified for screen "Default Screen". Using the first device section listed. (**) | |-->Device "Default Device" (==) No monitor specified for screen "Default Screen". Using a default monitor configuration. (==) Automatically adding devices (==) Automatically enabling devices (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist. Entry deleted from font path. (==) FontPath set to: /usr/share/fonts/X11/misc, /usr/share/fonts/X11/100dpi/:unscaled, /usr/share/fonts/X11/75dpi/:unscaled, /usr/share/fonts/X11/Type1, /usr/share/fonts/X11/100dpi, /usr/share/fonts/X11/75dpi, /var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType, built-ins (==) ModulePath set to "/usr/lib/xorg/extra-modules,/usr/lib/xorg/modules" (II) The server relies on udev to provide the list of input devices. If no devices become available, reconfigure udev or disable AutoAddDevices. (II) Loader magic: 0x81f0e80 (II) Module ABI versions: X.Org ANSI C Emulation: 0.4 X.Org Video Driver: 6.0 X.Org XInput driver : 7.0 X.Org Server Extension : 2.0 (++) using VT number 7 (--) PCI:*(0:1:0:0) 1002:9442:174b:e104 ATI Technologies Inc RV770 [Radeon HD 4850] rev 0, Mem @ 0xc0000000/268435456, 0xfe7e0000/65536, I/O @ 0x0000a000/256, BIOS @ 0x????????/131072 (--) PCI: (0:2:0:0) 1002:954f:1462:1618 ATI Technologies Inc RV710 [Radeon HD 4350] rev 0, Mem @ 0xd0000000/268435456, 0xfe8e0000/65536, I/O @ 0x0000b000/256, BIOS @ 0x????????/131072 (WW) Open ACPI failed (/var/run/acpid.socket) (No such file or directory) (II) "extmod" will be loaded by default. (II) "dbe" will be loaded by default. (II) "glx" will be loaded. This was enabled by default and also specified in the config file. (II) "record" will be loaded by default. (II) "dri" will be loaded by default. (II) "dri2" will be loaded by default. (II) LoadModule: "glx" (II) Loading /usr/lib/xorg/extra-modules/modules/extensions/libglx.so (II) Module glx: vendor="FireGL - ATI Technologies Inc." compiled for 7.5.0, module version = 1.0.0 (II) Loading extension GLX (II) LoadModule: "extmod" (II) Loading /usr/lib/xorg/modules/extensions/libextmod.so (II) Module extmod: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.0.0 Module class: X.Org Server Extension ABI class: X.Org Server Extension, version 2.0 (II) Loading extension MIT-SCREEN-SAVER (II) Loading extension XFree86-VidModeExtension (II) Loading extension XFree86-DGA (II) Loading extension DPMS (II) Loading extension XVideo (II) Loading extension XVideo-MotionCompensation (II) Loading extension X-Resource (II) LoadModule: "dbe" (II) Loading /usr/lib/xorg/modules/extensions/libdbe.so (II) Module dbe: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.0.0 Module class: X.Org Server Extension ABI class: X.Org Server Extension, version 2.0 (II) Loading extension DOUBLE-BUFFER (II) LoadModule: "record" (II) Loading /usr/lib/xorg/modules/extensions/librecord.so (II) Module record: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.13.0 Module class: X.Org Server Extension ABI class: X.Org Server Extension, version 2.0 (II) Loading extension RECORD (II) LoadModule: "dri" (II) Loading /usr/lib/xorg/modules/extensions/libdri.so (II) Module dri: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.0.0 ABI class: X.Org Server Extension, version 2.0 (II) Loading extension XFree86-DRI (II) LoadModule: "dri2" (II) Loading /usr/lib/xorg/modules/extensions/libdri2.so (II) Module dri2: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.1.0 ABI class: X.Org Server Extension, version 2.0 (II) Loading extension DRI2 (II) LoadModule: "fglrx" (II) Loading /usr/lib/xorg/extra-modules/modules/drivers/fglrx_drv.so (II) Module fglrx: vendor="FireGL - ATI Technologies Inc." compiled for 1.7.1, module version = 8.72.11 Module class: X.Org Video Driver (II) Loading sub module "fglrxdrm" (II) LoadModule: "fglrxdrm" (II) Loading /usr/lib/xorg/extra-modules/modules/linux/libfglrxdrm.so (II) Module fglrxdrm: vendor="FireGL - ATI Technologies Inc." compiled for 1.7.1, module version = 8.72.11 (II) ATI Proprietary Linux Driver Version Identifier:8.72.11 (II) ATI Proprietary Linux Driver Release Identifier: 8.723.1 (II) ATI Proprietary Linux Driver Build Date: Apr 8 2010 21:40:29 (II) Primary Device is: PCI 01@00:00:0 (WW) Falling back to old probe method for fglrx (II) Loading PCS database from /etc/ati/amdpcsdb (--) Assigning device section with no busID to primary device (WW) fglrx: No matching Device section for instance (BusID PCI:0@2:0:0) found (--) Chipset Supported AMD Graphics Processor (0x9442) found (WW) fglrx: No matching Device section for instance (BusID PCI:0@1:0:1) found (WW) fglrx: No matching Device section for instance (BusID PCI:0@2:0:1) found (**) ChipID override: 0x954F (**) Chipset Supported AMD Graphics Processor (0x954F) found (II) AMD Video driver is running on a device belonging to a group targeted for this release (II) AMD Video driver is signed (II) fglrx(0): pEnt->device->identifier=0x9428aa0 (II) pEnt->device->identifier=(nil) (II) fglrx(0): === [atiddxPreInit] === begin (II) Loading sub module "vgahw" (II) LoadModule: "vgahw" (II) Loading /usr/lib/xorg/modules/libvgahw.so (II) Module vgahw: vendor="X.Org Foundation" compiled for 1.7.6, module version = 0.1.0 ABI class: X.Org Video Driver, version 6.0 (II) fglrx(0): Creating default Display subsection in Screen section "Default Screen" for depth/fbbpp 24/32 (**) fglrx(0): Depth 24, (--) framebuffer bpp 32 (II) fglrx(0): Pixel depth = 24 bits stored in 4 bytes (32 bpp pixmaps) (==) fglrx(0): Default visual is TrueColor (==) fglrx(0): RGB weight 888 (II) fglrx(0): Using 8 bits per RGB (==) fglrx(0): Buffer Tiling is ON (II) Loading sub module "fglrxdrm" (II) LoadModule: "fglrxdrm" (II) Reloading /usr/lib/xorg/extra-modules/modules/linux/libfglrxdrm.so ukiDynamicMajor: found major device number 251 ukiDynamicMajor: found major device number 251 ukiOpenByBusid: Searching for BusID PCI:1:0:0 ukiOpenDevice: node name is /dev/ati/card0 ukiOpenDevice: open result is 10, (OK) ukiOpenByBusid: ukiOpenMinor returns 10 ukiOpenByBusid: ukiGetBusid reports PCI:2:0:0 ukiOpenDevice: node name is /dev/ati/card1 ukiOpenDevice: open result is 10, (OK) ukiOpenByBusid: ukiOpenMinor returns 10 ukiOpenByBusid: ukiGetBusid reports PCI:1:0:0 ukiDynamicMajor: found major device number 251 ukiDynamicMajor: found major device number 251 ukiOpenByBusid: Searching for BusID PCI:2:0:0 ukiOpenDevice: node name is /dev/ati/card0 ukiOpenDevice: open result is 11, (OK) ukiOpenByBusid: ukiOpenMinor returns 11 ukiOpenByBusid: ukiGetBusid reports PCI:2:0:0 (--) fglrx(0): Chipset: "ATI Radeon HD 4800 Series" (Chipset = 0x9442) (--) fglrx(0): (PciSubVendor = 0x174b, PciSubDevice = 0xe104) (==) fglrx(0): board vendor info: third party graphics adapter - NOT original ATI (--) fglrx(0): Linear framebuffer (phys) at 0xc0000000 (--) fglrx(0): MMIO registers at 0xfe7e0000 (--) fglrx(0): I/O port at 0x0000a000 (==) fglrx(0): ROM-BIOS at 0x000c0000 (II) fglrx(0): AC Adapter is used (II) fglrx(0): Primary V_BIOS segment is: 0xc000 (II) Loading sub module "vbe" (II) LoadModule: "vbe" (II) Loading /usr/lib/xorg/modules/libvbe.so (II) Module vbe: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.1.0 ABI class: X.Org Video Driver, version 6.0 (II) fglrx(0): VESA BIOS detected (II) fglrx(0): VESA VBE Version 3.0 (II) fglrx(0): VESA VBE Total Mem: 16384 kB (II) fglrx(0): VESA VBE OEM: ATI ATOMBIOS (II) fglrx(0): VESA VBE OEM Software Rev: 11.13 (II) fglrx(0): VESA VBE OEM Vendor: (C) 1988-2005, ATI Technologies Inc. (II) fglrx(0): VESA VBE OEM Product: RV770 (II) fglrx(0): VESA VBE OEM Product Rev: 01.00 (II) fglrx(0): ATI Video BIOS revision 9 or later detected (--) fglrx(0): Video RAM: 524288 kByte, Type: GDDR3 (II) fglrx(0): PCIE card detected (--) fglrx(0): Using per-process page tables (PPPT) as GART. (WW) fglrx(0): board is an unknown third party board, chipset is supported (--) fglrx(0): Chipset: "ATI Radeon HD 4300/4500 Series" (Chipset = 0x954f) (--) fglrx(0): (PciSubVendor = 0x1462, PciSubDevice = 0x1618) (==) fglrx(0): board vendor info: third party graphics adapter - NOT original ATI (--) fglrx(0): Linear framebuffer (phys) at 0xd0000000 (--) fglrx(0): MMIO registers at 0xfe8e0000 (--) fglrx(0): I/O port at 0x0000b000 (==) fglrx(0): ROM-BIOS at 0x000c0000 (II) fglrx(0): AC Adapter is used (II) fglrx(0): Invalid ATI BIOS from int10, the adapter is not VGA-enabled (II) fglrx(0): ATI Video BIOS revision 9 or later detected (--) fglrx(0): Video RAM: 524288 kByte, Type: DDR2 (II) fglrx(0): PCIE card detected (--) fglrx(0): Using per-process page tables (PPPT) as GART. (WW) fglrx(0): board is an unknown third party board, chipset is supported (II) fglrx(0): Using adapter: 1:0.0. (II) fglrx(0): [FB] MC range(MCFBBase = 0xf00000000, MCFBSize = 0x20000000) (II) fglrx(0): Interrupt handler installed at IRQ 31. (II) fglrx(0): Using adapter: 2:0.0. (II) fglrx(0): [FB] MC range(MCFBBase = 0xf00000000, MCFBSize = 0x20000000) (II) fglrx(0): RandR 1.2 support is enabled! (II) fglrx(0): RandR 1.2 rotation support is enabled! (==) fglrx(0): Center Mode is disabled (II) Loading sub module "fb" (II) LoadModule: "fb" (II) Loading /usr/lib/xorg/modules/libfb.so (II) Module fb: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.0.0 ABI class: X.Org ANSI C Emulation, version 0.4 (II) Loading sub module "ddc" (II) LoadModule: "ddc" (II) Module "ddc" already built-in (II) fglrx(0): Finished Initialize PPLIB! (II) Loading sub module "ddc" (II) LoadModule: "ddc" (II) Module "ddc" already built-in (II) fglrx(0): Connected Display0: DFP on external TMDS [tmds2] (II) fglrx(0): Display0 EDID data --------------------------- (II) fglrx(0): Manufacturer: DEL Model: a038 Serial#: 810829397 (II) fglrx(0): Year: 2008 Week: 51 (II) fglrx(0): EDID Version: 1.3 (II) fglrx(0): Digital Display Input (II) fglrx(0): Max Image Size [cm]: horiz.: 53 vert.: 30 (II) fglrx(0): Gamma: 2.20 (II) fglrx(0): DPMS capabilities: StandBy Suspend Off (II) fglrx(0): Supported color encodings: RGB 4:4:4 YCrCb 4:4:4 (II) fglrx(0): Default color space is primary color space (II) fglrx(0): First detailed timing is preferred mode (II) fglrx(0): redX: 0.640 redY: 0.330 greenX: 0.300 greenY: 0.600 (II) fglrx(0): blueX: 0.150 blueY: 0.060 whiteX: 0.312 whiteY: 0.329 (II) fglrx(0): Supported established timings: (II) fglrx(0): 720x400@70Hz (II) fglrx(0): 640x480@60Hz (II) fglrx(0): 640x480@75Hz (II) fglrx(0): 800x600@60Hz (II) fglrx(0): 800x600@75Hz (II) fglrx(0): 1024x768@60Hz (II) fglrx(0): 1024x768@75Hz (II) fglrx(0): 1280x1024@75Hz (II) fglrx(0): Manufacturer's mask: 0 (II) fglrx(0): Supported standard timings: (II) fglrx(0): #0: hsize: 1152 vsize 864 refresh: 75 vid: 20337 (II) fglrx(0): #1: hsize: 1280 vsize 1024 refresh: 60 vid: 32897 (II) fglrx(0): #2: hsize: 1920 vsize 1080 refresh: 60 vid: 49361 (II) fglrx(0): Supported detailed timing: (II) fglrx(0): clock: 148.5 MHz Image Size: 531 x 298 mm (II) fglrx(0): h_active: 1920 h_sync: 2008 h_sync_end 2052 h_blank_end 2200 h_border: 0 (II) fglrx(0): v_active: 1080 v_sync: 1084 v_sync_end 1089 v_blanking: 1125 v_border: 0 (II) fglrx(0): Serial No: Y183D8CF0TFU (II) fglrx(0): Monitor name: DELL S2409W (II) fglrx(0): Ranges: V min: 50 V max: 76 Hz, H min: 30 H max: 83 kHz, PixClock max 170 MHz (II) fglrx(0): EDID (in hex): (II) fglrx(0): 00ffffffffffff0010ac38a055465430 (II) fglrx(0): 3312010380351e78eeee91a3544c9926 (II) fglrx(0): 0f5054a54b00714f8180d1c001010101 (II) fglrx(0): 010101010101023a801871382d40582c (II) fglrx(0): 4500132a2100001e000000ff00593138 (II) fglrx(0): 3344384346305446550a000000fc0044 (II) fglrx(0): 454c4c205332343039570a20000000fd (II) fglrx(0): 00324c1e5311000a2020202020200059 (II) fglrx(0): End of Display0 EDID data -------------------- (II) fglrx(0): Output DFP2 has no monitor section (II) fglrx(0): Output DFP_EXTTMDS has no monitor section (II) fglrx(0): Output CRT1 has no monitor section (II) fglrx(0): Output CRT2 has no monitor section (II) fglrx(0): Output DFP2 disconnected (II) fglrx(0): Output DFP_EXTTMDS connected (II) fglrx(0): Output CRT1 disconnected (II) fglrx(0): Output CRT2 disconnected (II) fglrx(0): Using exact sizes for initial modes (II) fglrx(0): Output DFP_EXTTMDS using initial mode 1920x1080 (II) fglrx(0): DPI set to (96, 96) (II) fglrx(0): Adapter ATI Radeon HD 4800 Series has 2 configurable heads and 1 displays connected. (==) fglrx(0): QBS disabled (==) fglrx(0): PseudoColor visuals disabled (II) Loading sub module "ramdac" (II) LoadModule: "ramdac" (II) Module "ramdac" already built-in (==) fglrx(0): NoAccel = NO (==) fglrx(0): NoDRI = NO (==) fglrx(0): Capabilities: 0x00000000 (==) fglrx(0): CapabilitiesEx: 0x00000000 (==) fglrx(0): OpenGL ClientDriverName: "fglrx_dri.so" (==) fglrx(0): UseFastTLS=0 (==) fglrx(0): BlockSignalsOnLock=1 (--) Depth 24 pixmap format is 32 bpp (II) Loading extension ATIFGLRXDRI (II) fglrx(0): doing swlDriScreenInit (II) fglrx(0): swlDriScreenInit for fglrx driver ukiDynamicMajor: found major device number 251 ukiDynamicMajor: found major device number 251 ukiDynamicMajor: found major device number 251 ukiOpenByBusid: Searching for BusID PCI:1:0:0 ukiOpenDevice: node name is /dev/ati/card0 ukiOpenDevice: open result is 17, (OK) ukiOpenByBusid: ukiOpenMinor returns 17 ukiOpenByBusid: ukiGetBusid reports PCI:2:0:0 ukiOpenDevice: node name is /dev/ati/card1 ukiOpenDevice: open result is 17, (OK) ukiOpenByBusid: ukiOpenMinor returns 17 ukiOpenByBusid: ukiGetBusid reports PCI:1:0:0 (II) fglrx(0): [uki] DRM interface version 1.0 (II) fglrx(0): [uki] created "fglrx" driver at busid "PCI:1:0:0" (II) fglrx(0): [uki] added 8192 byte SAREA at 0x2000 (II) fglrx(0): [uki] mapped SAREA 0x2000 to 0xb6996000 (II) fglrx(0): [uki] framebuffer handle = 0x3000 (II) fglrx(0): [uki] added 1 reserved context for kernel (II) fglrx(0): swlDriScreenInit done (II) fglrx(0): Kernel Module Version Information: (II) fglrx(0): Name: fglrx (II) fglrx(0): Version: 8.72.11 (II) fglrx(0): Date: Apr 8 2010 (II) fglrx(0): Desc: ATI FireGL DRM kernel module (II) fglrx(0): Kernel Module version matches driver. (II) fglrx(0): Kernel Module Build Time Information: (II) fglrx(0): Build-Kernel UTS_RELEASE: 2.6.32-22-generic-pae (II) fglrx(0): Build-Kernel MODVERSIONS: yes (II) fglrx(0): Build-Kernel __SMP__: yes (II) fglrx(0): Build-Kernel PAGE_SIZE: 0x1000 (II) fglrx(0): [uki] register handle = 0x00004000 (II) fglrx(0): DRI initialization successfull! (II) fglrx(0): FBADPhys: 0xf00000000 FBMappedSize: 0x01068000 (II) fglrx(0): FBMM initialized for area (0,0)-(1920,2240) (II) fglrx(0): FBMM auto alloc for area (0,0)-(1920,1920) (front color buffer - assumption) (II) fglrx(0): Largest offscreen area available: 1920 x 320 (==) fglrx(0): Backing store disabled (II) Loading extension FGLRXEXTENSION (==) fglrx(0): DPMS enabled (II) fglrx(0): Initialized in-driver Xinerama extension (**) fglrx(0): Textured Video is enabled. (II) LoadModule: "glesx" (II) Loading /usr/lib/xorg/extra-modules/modules/glesx.so (II) Module glesx: vendor="X.Org Foundation" compiled for 1.7.1, module version = 1.0.0 (II) Loading extension GLESX (II) Loading sub module "xaa" (II) LoadModule: "xaa" (II) Loading /usr/lib/xorg/modules/libxaa.so (II) Module xaa: vendor="X.Org Foundation" compiled for 1.7.6, module version = 1.2.1 ABI class: X.Org Video Driver, version 6.0 (II) fglrx(0): GLESX enableFlags = 94 (II) fglrx(0): Using XFree86 Acceleration Architecture (XAA) Screen to screen bit blits Solid filled rectangles Solid Horizontal and Vertical Lines Driver provided ScreenToScreenBitBlt replacement Driver provided FillSolidRects replacement (II) fglrx(0): GLESX is enabled (II) LoadModule: "amdxmm" (II) Loading /usr/lib/xorg/extra-modules/modules/amdxmm.so (II) Module amdxmm: vendor="X.Org Foundation" compiled for 1.7.1, module version = 1.0.0 (II) Loading extension AMDXVOPL (II) fglrx(0): UVD2 feature is available (II) fglrx(0): Enable composite support successfully (II) fglrx(0): X context handle = 0x1 (II) fglrx(0): [DRI] installation complete (==) fglrx(0): Silken mouse enabled (==) fglrx(0): Using HW cursor of display infrastructure! (II) fglrx(0): Disabling in-server RandR and enabling in-driver RandR 1.2. (--) RandR disabled (II) Found 2 VGA devices: arbiter wrapping enabled (II) Initializing built-in extension Generic Event Extension (II) Initializing built-in extension SHAPE (II) Initializing built-in extension MIT-SHM (II) Initializing built-in extension XInputExtension (II) Initializing built-in extension XTEST (II) Initializing built-in extension BIG-REQUESTS (II) Initializing built-in extension SYNC (II) Initializing built-in extension XKEYBOARD (II) Initializing built-in extension XC-MISC (II) Initializing built-in extension SECURITY (II) Initializing built-in extension XINERAMA (II) Initializing built-in extension XFIXES (II) Initializing built-in extension RENDER (II) Initializing built-in extension RANDR (II) Initializing built-in extension COMPOSITE (II) Initializing built-in extension DAMAGE ukiDynamicMajor: found major device number 251 ukiDynamicMajor: found major device number 251 ukiOpenByBusid: Searching for BusID PCI:1:0:0 ukiOpenDevice: node name is /dev/ati/card0 ukiOpenDevice: open result is 18, (OK) ukiOpenByBusid: ukiOpenMinor returns 18 ukiOpenByBusid: ukiGetBusid reports PCI:2:0:0 ukiOpenDevice: node name is /dev/ati/card1 ukiOpenDevice: open result is 18, (OK) ukiOpenByBusid: ukiOpenMinor returns 18 ukiOpenByBusid: ukiGetBusid reports PCI:1:0:0 (II) AIGLX: Loaded and initialized /usr/lib/dri/fglrx_dri.so (II) GLX: Initialized DRI GL provider for screen 0 (II) fglrx(0): Enable the clock gating! (II) fglrx(0): Setting screen physical size to 507 x 285 (II) XKB: reuse xkmfile /var/lib/xkb/server-B20D7FC79C7F597315E3E501AEF10E0D866E8E92.xkm (II) config/udev: Adding input device Power Button (/dev/input/event1) (**) Power Button: Applying InputClass "evdev keyboard catchall" (II) LoadModule: "evdev" (II) Loading /usr/lib/xorg/modules/input/evdev_drv.so (II) Module evdev: vendor="X.Org Foundation" compiled for 1.7.6, module version = 2.3.2 Module class: X.Org XInput Driver ABI class: X.Org XInput driver, version 7.0 (**) Power Button: always reports core events (**) Power Button: Device: "/dev/input/event1" (II) Power Button: Found keys (II) Power Button: Configuring as keyboard (II) XINPUT: Adding extended input device "Power Button" (type: KEYBOARD) (**) Option "xkb_rules" "evdev" (**) Option "xkb_model" "pc105" (**) Option "xkb_layout" "us" (II) config/udev: Adding input device Power Button (/dev/input/event0) (**) Power Button: Applying InputClass "evdev keyboard catchall" (**) Power Button: always reports core events (**) Power Button: Device: "/dev/input/event0" (II) Power Button: Found keys (II) Power Button: Configuring as keyboard (II) XINPUT: Adding extended input device "Power Button" (type: KEYBOARD) (**) Option "xkb_rules" "evdev" (**) Option "xkb_model" "pc105" (**) Option "xkb_layout" "us" (II) config/udev: Adding input device Logitech USB-PS/2 Optical Mouse (/dev/input/event3) (**) Logitech USB-PS/2 Optical Mouse: Applying InputClass "evdev pointer catchall" (**) Logitech USB-PS/2 Optical Mouse: always reports core events (**) Logitech USB-PS/2 Optical Mouse: Device: "/dev/input/event3" (II) Logitech USB-PS/2 Optical Mouse: Found 12 mouse buttons (II) Logitech USB-PS/2 Optical Mouse: Found scroll wheel(s) (II) Logitech USB-PS/2 Optical Mouse: Found relative axes (II) Logitech USB-PS/2 Optical Mouse: Found x and y relative axes (II) Logitech USB-PS/2 Optical Mouse: Configuring as mouse (**) Logitech USB-PS/2 Optical Mouse: YAxisMapping: buttons 4 and 5 (**) Logitech USB-PS/2 Optical Mouse: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200 (II) XINPUT: Adding extended input device "Logitech USB-PS/2 Optical Mouse" (type: MOUSE) (II) Logitech USB-PS/2 Optical Mouse: initialized for relative axes. (II) config/udev: Adding input device Logitech USB-PS/2 Optical Mouse (/dev/input/mouse1) (II) No input driver/identifier specified (ignoring) (II) config/udev: Adding input device Logitech USB Multimedia Keyboard (/dev/input/event4) (**) Logitech USB Multimedia Keyboard: Applying InputClass "evdev keyboard catchall" (**) Logitech USB Multimedia Keyboard: always reports core events (**) Logitech USB Multimedia Keyboard: Device: "/dev/input/event4" (II) Logitech USB Multimedia Keyboard: Found keys (II) Logitech USB Multimedia Keyboard: Configuring as keyboard (II) XINPUT: Adding extended input device "Logitech USB Multimedia Keyboard" (type: KEYBOARD) (**) Option "xkb_rules" "evdev" (**) Option "xkb_model" "pc105" (**) Option "xkb_layout" "us" (II) config/udev: Adding input device Logitech USB Multimedia Keyboard (/dev/input/event5) (**) Logitech USB Multimedia Keyboard: Applying InputClass "evdev keyboard catchall" (**) Logitech USB Multimedia Keyboard: always reports core events (**) Logitech USB Multimedia Keyboard: Device: "/dev/input/event5" (II) Logitech USB Multimedia Keyboard: Found keys (II) Logitech USB Multimedia Keyboard: Configuring as keyboard (II) XINPUT: Adding extended input device "Logitech USB Multimedia Keyboard" (type: KEYBOARD) (**) Option "xkb_rules" "evdev" (**) Option "xkb_model" "pc105" (**) Option "xkb_layout" "us" (II) config/udev: Adding input device KEYBOARD (/dev/input/event6) (**) KEYBOARD: Applying InputClass "evdev keyboard catchall" (**) KEYBOARD: always reports core events (**) KEYBOARD: Device: "/dev/input/event6" (II) KEYBOARD: Found keys (II) KEYBOARD: Configuring as keyboard (II) XINPUT: Adding extended input device "KEYBOARD" (type: KEYBOARD) (**) Option "xkb_rules" "evdev" (**) Option "xkb_model" "pc105" (**) Option "xkb_layout" "us" (II) config/udev: Adding input device KEYBOARD (/dev/input/event7) (**) KEYBOARD: Applying InputClass "evdev keyboard catchall" (**) KEYBOARD: always reports core events (**) KEYBOARD: Device: "/dev/input/event7" (II) KEYBOARD: Found 14 mouse buttons (II) KEYBOARD: Found scroll wheel(s) (II) KEYBOARD: Found relative axes (II) KEYBOARD: Found keys (II) KEYBOARD: Configuring as mouse (II) KEYBOARD: Configuring as keyboard (**) KEYBOARD: YAxisMapping: buttons 4 and 5 (**) KEYBOARD: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200 (II) XINPUT: Adding extended input device "KEYBOARD" (type: KEYBOARD) (**) Option "xkb_rules" "evdev" (**) Option "xkb_model" "pc105" (**) Option "xkb_layout" "us" (EE) KEYBOARD: failed to initialize for relative axes. (II) config/udev: Adding input device KEYBOARD (/dev/input/mouse2) (II) No input driver/identifier specified (ignoring) (II) config/udev: Adding input device Macintosh mouse button emulation (/dev/input/event2) (**) Macintosh mouse button emulation: Applying InputClass "evdev pointer catchall" (**) Macintosh mouse button emulation: always reports core events (**) Macintosh mouse button emulation: Device: "/dev/input/event2" (II) Macintosh mouse button emulation: Found 3 mouse buttons (II) Macintosh mouse button emulation: Found relative axes (II) Macintosh mouse button emulation: Found x and y relative axes (II) Macintosh mouse button emulation: Configuring as mouse (**) Macintosh mouse button emulation: YAxisMapping: buttons 4 and 5 (**) Macintosh mouse button emulation: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200 (II) XINPUT: Adding extended input device "Macintosh mouse button emulation" (type: MOUSE) (II) Macintosh mouse button emulation: initialized for relative axes. (II) config/udev: Adding input device Macintosh mouse button emulation (/dev/input/mouse0) (II) No input driver/identifier specified (ignoring) (II) fglrx(0): Restoring Recent Mode via PCS is not supported in RANDR 1.2 capable environments

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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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• ASP.NET Hosting :: ASP.NET File Upload Control

  - by mbridge

  The asp.net FileUpload control allows a user to browse and upload files to the web server. From developers perspective, it is as simple as dragging and dropping the FileUpload control to the aspx page. An extra control, like a Button control, or some other control is needed, to actually save the file. <asp:FileUploadID="FileUpload1"runat="server"/> <asp:ButtonID="B1"runat="server"Text="Save"OnClick="B1_Click"/> By default, the FileUpload control allows a maximum of 4MB file to be uploaded and the execution timeout is 110 seconds. These properties can be changed from within the web.config file’s httpRuntime section. The maxRequestLength property determines the maximum file size that can be uploaded. The executionTimeout property determines the maximum time for execution. <httpRuntimemaxRequestLength="8192"executionTimeout="220"/> From code behind, the mime type, size of the file, file name and the extension of the file can be obtained. The maximum file size that can be uploaded can be obtained and modified using the System.Web.Configuration.HttpRuntimeSection class. Files can be alternatively saved using the System.IO.HttpFileCollection class. This collection class can be populated using the Request.Files property. The collection contains HttpPostedFile class which contains a reference to the class. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.IO; using System.Configuration; using System.Web.Configuration;   namespace WebApplication1 {     public partial class WebControls : System.Web.UI.Page     {         protected void Page_Load(object sender, EventArgs e)         {         }           //Using FileUpload control to upload and save files         protected void B1_Click(object sender, EventArgs e)         {             if (FileUpload1.HasFile && FileUpload1.PostedFile.ContentLength > 0)             {                 //mime type of the uploaded file                 string mimeType = FileUpload1.PostedFile.ContentType;                   //size of the uploaded file                 int size = FileUpload1.PostedFile.ContentLength; // bytes                   //extension of the uploaded file                 string extension = System.IO.Path.GetExtension(FileUpload1.FileName);                                  //save file                 string path = Server.MapPath("path");                                 FileUpload1.SaveAs(path + FileUpload1.FileName);                              }             //maximum file size allowed             HttpRuntimeSection rt = new HttpRuntimeSection();             rt.MaxRequestLength = rt.MaxRequestLength * 2;             int length = rt.MaxRequestLength;                     //execution timeout             TimeSpan ts = rt.ExecutionTimeout;             double secomds = ts.TotalSeconds;           }           //Using Request.Files to save files         private void AltSaveFile()         {             HttpFileCollection coll = Request.Files;             for (int i = 0; i < coll.Count; i++)             {                 HttpPostedFile file = coll[i];                   if (file.ContentLength > 0)                     ;//do something             }         }     } }

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• Implementing separation of concerns via MVC

  - by user2368481

  I'm creating a question to see if my understanding of MVC separation is correct, I haven't been able to find a clear answer anywhere online. So is this the right way to implement it (in Java): I would have 3 .java files, one each for Model, Controller, View. I would put all the classes related to Model in the Model.java like so: //Model.java { public class Model //class fields public Model(); public ModelClassA(); public ModelClassB(); public ModelClassC(); } With the ModelClasses being any class that I consider belonging to the Model. Is it correct to have the classes within the Model Class, as I have read that nested classes should be avoided where possible.

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• ADF Seeded Customizations in JDeveloper 11.1.2.1

  - by Dmitry Nefedkin

  For the ADF training I needed a demo application that shows ADF seeded customizations functionality. I’m using the latest JDeveloper 11.1.2.1, so I decided to download the “Customizing and Personalizing an ADF Application” completed tutorial application available here I’ve downloaded and unzipped the CustomizeApp.zip and opened the CustomizeApp.jws in the JDeveloper 11.1.2.1 using the Customization Role. The result was the following: MDS-00036 “Cannot instantiate the class oracle.model.mycompany.SiteCC”. I thought: “OK, that’s because SiteCC class is not accessible to JDeveloper classloader, I should jar it and put to the <JDEVELOPER_HOME> \jdev\lib\patches like I did in JDeveloper 11.1.1.5 and ealier”.  No way, it JDeveloper 11.1.2 we do not have this patches directory at all! It seems that is because of the new architecture of the JDeveloper plugins based on OSGi.   I looked through the tutorial and have not found any step related to the jar–ing the SiteCC class and moving it to the specific directory.  So, JDeveloper 11.1.2  is smart enough to find my customization class and add it to the classpath without any specific actions from my side.  But why am I getting this “cannot instantiate the class” error?I’ve checked at the the full path to my CustomizeApp.jws  - c:\temp\ADF personalizations\CustomizeApp\CustomizeApp.jws  and noticed the space in the name of the directory.  Was it the root cause of the issue?  Yes!  I’ve renamed the ADF personalizations folder to pers, opened the c:\temp\pers\CustomizeApp\CustomizeApp.jws,  and received the expected behaviour: So, be aware of the spaces in the paths when working with JDeveloper…

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• How to store Role Based Access rights in web application?

  - by JonH

  Currently working on a web based CRM type system that deals with various Modules such as Companies, Contacts, Projects, Sub Projects, etc. A typical CRM type system (asp.net web form, C#, SQL Server backend). We plan to implement role based security so that basically a user can have one or more roles. Roles would be broken down by first the module type such as: -Company -Contact And then by the actions for that module for instance each module would end up with a table such as this: Role1 Example: Module Create Edit Delete View Company Yes Owner Only No Yes Contact Yes Yes Yes Yes In the above case Role1 has two module types (Company, and Contact). For company, the person assigned to this role can create companies, can view companies, can only edit records he/she created and cannot delete. For this same role for the module contact this user can create contacts, edit contacts, delete contacts, and view contacts (full rights basically). I am wondering is it best upon coming into the system to session the user's role with something like a: List<Role> roles; Where the Role class would have some sort of List<Module> modules; (can contain Company, Contact, etc.).? Something to the effect of: class Role{ string name; string desc; List<Module> modules; } And the module action class would have a set of actions (Create, Edit, Delete, etc.) for each module: class ModuleActions{ List<Action> actions; } And the action has a value of whether the user can perform the right: class Action{ string right; } Just a rough idea, I know the action could be an enum and the ModuleAction can probably be eliminated with a List<x, y>. My main question is what would be the best way to store this information in this type of application: Should I store it in the User Session state (I have a session class where I manage things related to the user). I generally load this during the initial loading of the application (global.asax). I can simply tack onto this session. Or should this be loaded at the page load event of each module (page load of company etc..). I eventually need to be able to hide / unhide various buttons / divs based on the user's role and that is what got me thinking to load this via session. Any examples or points would be great.

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• Why enumerator structs are a really bad idea

  - by Simon Cooper

  If you've ever poked around the .NET class libraries in Reflector, I'm sure you would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects... As is generally known in the .NET world, mutable structs are a Very Bad Idea; and there are several other blogs around explaining this (Eric Lippert's blog post explains the problem quite well). In the BCL, the generic collection enumerators are all mutable structs, as they need to keep track of where they are in the collection. This bit me quite hard when I was coding a wrapper around a LinkedList<int>.Enumerator. It boils down to this code: sealed class EnumeratorWrapper : IEnumerator<int> { private readonly LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } The key line here is the MoveNext method. When I initially coded this, I thought that the call to m_Enumerator.MoveNext() would alter the enumerator state in the m_Enumerator class variable and so the enumeration would proceed in an orderly fashion through the collection. However, when I ran this code it went into an infinite loop - the m_Enumerator.MoveNext() call wasn't actually changing the state in the m_Enumerator variable at all, and my code was looping forever on the first collection element. It was only after disassembling that method that I found out what was going on The MoveNext method above results in the following IL: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000, [1] valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator CS$0$0001) L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: stloc.1 L_0008: ldloca.s CS$0$0001 L_000a: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000f: stloc.0 L_0010: br.s L_0012 L_0012: ldloc.0 L_0013: ret } Here, the important line is 0002 - m_Enumerator is accessed using the ldfld operator, which does the following: Finds the value of a field in the object whose reference is currently on the evaluation stack. So, what the MoveNext method is doing is the following: public bool MoveNext() { LinkedList<int>.Enumerator CS$0$0001 = this.m_Enumerator; bool CS$1$0000 = CS$0$0001.MoveNext(); return CS$1$0000; } The enumerator instance being modified by the call to MoveNext is the one stored in the CS$0$0001 variable on the stack, and not the one in the EnumeratorWrapper class instance. Hence why the state of m_Enumerator wasn't getting updated. Hmm, ok. Well, why is it doing this? If you have a read of Eric Lippert's blog post about this issue, you'll notice he quotes a few sections of the C# spec. In particular, 7.5.4: ...if the field is readonly and the reference occurs outside an instance constructor of the class in which the field is declared, then the result is a value, namely the value of the field I in the object referenced by E. And my m_Enumerator field is readonly! Indeed, if I remove the readonly from the class variable then the problem goes away, and the code works as expected. The IL confirms this: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000) L_0000: nop L_0001: ldarg.0 L_0002: ldflda valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000c: stloc.0 L_000d: br.s L_000f L_000f: ldloc.0 L_0010: ret } Notice on line 0002, instead of the ldfld we had before, we've got a ldflda, which does this: Finds the address of a field in the object whose reference is currently on the evaluation stack. Instead of loading the value, we're loading the address of the m_Enumerator field. So now the call to MoveNext modifies the enumerator stored in the class rather than on the stack, and everything works as expected. Previously, I had thought enumerator structs were an odd but interesting feature of the BCL that I had used in the past to do linked list slices. However, effects like this only underline how dangerous mutable structs are, and I'm at a loss to explain why the enumerators were implemented as structs in the first place. (interestingly, the SortedList<TKey, TValue> enumerator is a struct but is private, which makes it even more odd - the only way it can be accessed is as a boxed IEnumerator!). I would love to hear people's theories as to why the enumerators are implemented in such a fashion. And bonus points if you can explain why LinkedList<int>.Enumerator.Reset is an explicit implementation but Dispose is implicit... Note to self: never ever ever code a mutable struct.

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