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  • Authoritative sources about Database vs. Flatfile decision

    - by FastAl
    <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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  • A Communication System for XAML Applications

    - by psheriff
    In any application, you want to keep the coupling between any two or more objects as loose as possible. Coupling happens when one class contains a property that is used in another class, or uses another class in one of its methods. If you have this situation, then this is called strong or tight coupling. One popular design pattern to help with keeping objects loosely coupled is called the Mediator design pattern. The basics of this pattern are very simple; avoid one object directly talking to another object, and instead use another class to mediate between the two. As with most of my blog posts, the purpose is to introduce you to a simple approach to using a message broker, not all of the fine details. IPDSAMessageBroker Interface As with most implementations of a design pattern, you typically start with an interface or an abstract base class. In this particular instance, an Interface will work just fine. The interface for our Message Broker class just contains a single method “SendMessage” and one event “MessageReceived”. public delegate void MessageReceivedEventHandler( object sender, PDSAMessageBrokerEventArgs e); public interface IPDSAMessageBroker{  void SendMessage(PDSAMessageBrokerMessage msg);   event MessageReceivedEventHandler MessageReceived;} PDSAMessageBrokerMessage Class As you can see in the interface, the SendMessage method requires a type of PDSAMessageBrokerMessage to be passed to it. This class simply has a MessageName which is a ‘string’ type and a MessageBody property which is of the type ‘object’ so you can pass whatever you want in the body. You might pass a string in the body, or a complete Customer object. The MessageName property will help the receiver of the message know what is in the MessageBody property. public class PDSAMessageBrokerMessage{  public PDSAMessageBrokerMessage()  {  }   public PDSAMessageBrokerMessage(string name, object body)  {    MessageName = name;    MessageBody = body;  }   public string MessageName { get; set; }   public object MessageBody { get; set; }} PDSAMessageBrokerEventArgs Class As our message broker class will be raising an event that others can respond to, it is a good idea to create your own event argument class. This class will inherit from the System.EventArgs class and add a couple of additional properties. The properties are the MessageName and Message. The MessageName property is simply a string value. The Message property is a type of a PDSAMessageBrokerMessage class. public class PDSAMessageBrokerEventArgs : EventArgs{  public PDSAMessageBrokerEventArgs()  {  }   public PDSAMessageBrokerEventArgs(string name,     PDSAMessageBrokerMessage msg)  {    MessageName = name;    Message = msg;  }   public string MessageName { get; set; }   public PDSAMessageBrokerMessage Message { get; set; }} PDSAMessageBroker Class Now that you have an interface class and a class to pass a message through an event, it is time to create your actual PDSAMessageBroker class. This class implements the SendMessage method and will also create the event handler for the delegate created in your Interface. public class PDSAMessageBroker : IPDSAMessageBroker{  public void SendMessage(PDSAMessageBrokerMessage msg)  {    PDSAMessageBrokerEventArgs args;     args = new PDSAMessageBrokerEventArgs(      msg.MessageName, msg);     RaiseMessageReceived(args);  }   public event MessageReceivedEventHandler MessageReceived;   protected void RaiseMessageReceived(    PDSAMessageBrokerEventArgs e)  {    if (null != MessageReceived)      MessageReceived(this, e);  }} The SendMessage method will take a PDSAMessageBrokerMessage object as an argument. It then creates an instance of a PDSAMessageBrokerEventArgs class, passing to the constructor two items: the MessageName from the PDSAMessageBrokerMessage object and also the object itself. It may seem a little redundant to pass in the message name when that same message name is part of the message, but it does make consuming the event and checking for the message name a little cleaner – as you will see in the next section. Create a Global Message Broker In your WPF application, create an instance of this message broker class in the App class located in the App.xaml file. Create a public property in the App class and create a new instance of that class in the OnStartUp event procedure as shown in the following code: public partial class App : Application{  public PDSAMessageBroker MessageBroker { get; set; }   protected override void OnStartup(StartupEventArgs e)  {    base.OnStartup(e);     MessageBroker = new PDSAMessageBroker();  }} Sending and Receiving Messages Let’s assume you have a user control that you load into a control on your main window and you want to send a message from that user control to the main window. You might have the main window display a message box, or put a string into a status bar as shown in Figure 1. Figure 1: The main window can receive and send messages The first thing you do in the main window is to hook up an event procedure to the MessageReceived event of the global message broker. This is done in the constructor of the main window: public MainWindow(){  InitializeComponent();   (Application.Current as App).MessageBroker.     MessageReceived += new MessageReceivedEventHandler(       MessageBroker_MessageReceived);} One piece of code you might not be familiar with is accessing a property defined in the App class of your XAML application. Within the App.Xaml file is a class named App that inherits from the Application object. You access the global instance of this App class by using Application.Current. You cast Application.Current to ‘App’ prior to accessing any of the public properties or methods you defined in the App class. Thus, the code (Application.Current as App).MessageBroker, allows you to get at the MessageBroker property defined in the App class. In the MessageReceived event procedure in the main window (shown below) you can now check to see if the MessageName property of the PDSAMessageBrokerEventArgs is equal to “StatusBar” and if it is, then display the message body into the status bar text block control. void MessageBroker_MessageReceived(object sender,   PDSAMessageBrokerEventArgs e){  switch (e.MessageName)  {    case "StatusBar":      tbStatus.Text = e.Message.MessageBody.ToString();      break;  }} In the Page 1 user control’s Loaded event procedure you will send the message “StatusBar” through the global message broker to any listener using the following code: private void UserControl_Loaded(object sender,  RoutedEventArgs e){  // Send Status Message  (Application.Current as App).MessageBroker.    SendMessage(new PDSAMessageBrokerMessage("StatusBar",      "This is Page 1"));} Since the main window is listening for the message ‘StatusBar’, it will display the value “This is Page 1” in the status bar at the bottom of the main window. Sending a Message to a User Control The previous example sent a message from the user control to the main window. You can also send messages from the main window to any listener as well. Remember that the global message broker is really just a broadcaster to anyone who has hooked into the MessageReceived event. In the constructor of the user control named ucPage1 you can hook into the global message broker’s MessageReceived event. You can then listen for any messages that are sent to this control by using a similar switch-case structure like that in the main window. public ucPage1(){  InitializeComponent();   // Hook to the Global Message Broker  (Application.Current as App).MessageBroker.    MessageReceived += new MessageReceivedEventHandler(      MessageBroker_MessageReceived);} void MessageBroker_MessageReceived(object sender,  PDSAMessageBrokerEventArgs e){  // Look for messages intended for Page 1  switch (e.MessageName)  {    case "ForPage1":      MessageBox.Show(e.Message.MessageBody.ToString());      break;  }} Once the ucPage1 user control has been loaded into the main window you can then send a message using the following code: private void btnSendToPage1_Click(object sender,  RoutedEventArgs e){  PDSAMessageBrokerMessage arg =     new PDSAMessageBrokerMessage();   arg.MessageName = "ForPage1";  arg.MessageBody = "Message For Page 1";   // Send a message to Page 1  (Application.Current as App).MessageBroker.SendMessage(arg);} Since the MessageName matches what is in the ucPage1 MessageReceived event procedure, ucPage1 can do anything in response to that event. It is important to note that when the message gets sent it is sent to all MessageReceived event procedures, not just the one that is looking for a message called “ForPage1”. If the user control ucPage1 is not loaded and this message is broadcast, but no other code is listening for it, then it is simply ignored. Remove Event Handler In each class where you add an event handler to the MessageReceived event you need to make sure to remove those event handlers when you are done. Failure to do so can cause a strong reference to the class and thus not allow that object to be garbage collected. In each of your user control’s make sure in the Unloaded event to remove the event handler. private void UserControl_Unloaded(object sender, RoutedEventArgs e){  if (_MessageBroker != null)    _MessageBroker.MessageReceived -=         _MessageBroker_MessageReceived;} Problems with Message Brokering As with most “global” classes or classes that hook up events to other classes, garbage collection is something you need to consider. Just the simple act of hooking up an event procedure to a global event handler creates a reference between your user control and the message broker in the App class. This means that even when your user control is removed from your UI, the class will still be in memory because of the reference to the message broker. This can cause messages to still being handled even though the UI is not being displayed. It is up to you to make sure you remove those event handlers as discussed in the previous section. If you don’t, then the garbage collector cannot release those objects. Instead of using events to send messages from one object to another you might consider registering your objects with a central message broker. This message broker now becomes a collection class into which you pass an object and what messages that object wishes to receive. You do end up with the same problem however. You have to un-register your objects; otherwise they still stay in memory. To alleviate this problem you can look into using the WeakReference class as a method to store your objects so they can be garbage collected if need be. Discussing Weak References is beyond the scope of this post, but you can look this up on the web. Summary In this blog post you learned how to create a simple message broker system that will allow you to send messages from one object to another without having to reference objects directly. This does reduce the coupling between objects in your application. You do need to remember to get rid of any event handlers prior to your objects going out of scope or you run the risk of having memory leaks and events being called even though you can no longer access the object that is responding to that event. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “A Communication System for XAML Applications” from the drop down list.

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  • Explicit method tables in C# instead of OO - good? bad?

    - by FunctorSalad
    Hi! I hope the title doesn't sound too subjective; I absolutely do not mean to start a debate on OO in general. I'd merely like to discuss the basic pros and cons for different ways of solving the following sort of problem. Let's take this minimal example: you want to express an abstract datatype T with functions that may take T as input, output, or both: f1 : Takes a T, returns an int f2 : Takes a string, returns a T f3 : Takes a T and a double, returns another T I'd like to avoid downcasting and any other dynamic typing. I'd also like to avoid mutation whenever possible. 1: Abstract-class-based attempt abstract class T { abstract int f1(); // We can't have abstract constructors, so the best we can do, as I see it, is: abstract void f2(string s); // The convention would be that you'd replace calls to the original f2 by invocation of the nullary constructor of the implementing type, followed by invocation of f2. f2 would need to have side-effects to be of any use. // f3 is a problem too: abstract T f3(double d); // This doesn't express that the return value is of the *same* type as the object whose method is invoked; it just expresses that the return value is *some* T. } 2: Parametric polymorphism and an auxilliary class (all implementing classes of TImpl will be singleton classes): abstract class TImpl<T> { abstract int f1(T t); abstract T f2(string s); abstract T f3(T t, double d); } We no longer express that some concrete type actually implements our original spec -- an implementation is simply a type Foo for which we happen to have an instance of TImpl. This doesn't seem to be a problem: If you want a function that works on arbitrary implementations, you just do something like: // Say we want to return a Bar given an arbitrary implementation of our abstract type Bar bar<T>(TImpl<T> ti, T t); At this point, one might as well skip inheritance and singletons altogether and use a 3 First-class function table class /* or struct, even */ TDictT<T> { readonly Func<T,int> f1; readonly Func<string,T> f2; readonly Func<T,double,T> f3; TDict( ... ) { this.f1 = f1; this.f2 = f2; this.f3 = f3; } } Bar bar<T>(TDict<T> td; T t); Though I don't see much practical difference between #2 and #3. Example Implementation class MyT { /* raw data structure goes here; this class needn't have any methods */ } // It doesn't matter where we put the following; could be a static method of MyT, or some static class collecting dictionaries static readonly TDict<MyT> MyTDict = new TDict<MyT>( (t) => /* body of f1 goes here */ , // f2 (s) => /* body of f2 goes here */, // f3 (t,d) => /* body of f3 goes here */ ); Thoughts? #3 is unidiomatic, but it seems rather safe and clean. One question is whether there are any performance concerns with it. I don't usually need dynamic dispatch, and I'd prefer if these function bodies get statically inlined in places where the concrete implementing type is known statically. Is #2 better in that regard?

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  • Unity3D draw call optimization : static batching VS manually draw mesh with MaterialPropertyBlock

    - by Heisenbug
    I've read Unity3D draw call batching documentation. I understood it, and I want to use it (or something similar) in order to optimize my application. My situation is the following: I'm drawing hundreds of 3d buildings. Each building can be represented using a Mesh (or a SubMesh for each building, but I don't thing this will affect performances) Each building can be textured with several combinations of texture patterns(walls, windows,..). Textures are stored into an Atlas for optimizaztion (see Texture2d.PackTextures) Texture mapping and facade pattern generation is done in fragment shader. The shader can be the same (except for few values) for all buildings, so I'd like to use a sharedMaterial in order to optimize parameters passed to the GPU. The main problem is that, even if I use an Atlas, share the material, and declare the objects as static to use static batching, there are few parameters(very fews, it could be just even a float I guess) that should be different for every draw call. I don't know exactly how to manage this situation using Unity3D. I'm trying 2 different solutions, none of them completely implemented. Solution 1 Build a GameObject for each building building (I don't like very much the overhead of a GameObject, anyway..) Prepare each GameObject to be static batched with StaticBatchingUtility.Combine. Pack all texture into an atlas Assign the parent game object of combined batched objects the Material (basically the shader and the atlas) Change some properties in the material before drawing an Object The problem is the point 5. Let's say I have to assign a different id to an object before drawing it, how can I do this? If I use a different material for each object I can't benefit of static batching. If I use a sharedMaterial and I modify a material property, all GameObjects will reference the same modified variable Solution 2 Build a Mesh for every building (sounds better, no GameObject overhead) Pack all textures into an Atlas Draw each mesh manually using Graphics.DrawMesh Customize each DrawMesh call using a MaterialPropertyBlock This would solve the issue related to slightly modify material properties for each draw call, but the documentation isn't clear on the following point: Does several consecutive calls to Graphic.DrawMesh with a different MaterialPropertyBlock would cause a new material to be instanced? Or Unity can understand that I'm modifying just few parameters while using the same material and is able to optimize that (in such a way that the big atlas is passed just once to the GPU)?

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  • iPhone 4 vs iPhone 3GS Comparison – Graphical Chart

    - by Gopinath
    600000 people pre-ordered iPhone 4 on a single day and this rush of fan boys left both Apple and AT & T web servers down for many hours. If you wonder why so many people are rushing for iPhone 4, here is the chart that explains the difference between iPhone 3GS and iPhone 4. As Steve Jobs said at WWDC 2010, iPhone 4 is definitely going to change smart phone game all over again. via Join us on Facebook to read all our stories right inside your Facebook news feed.

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  • OpenGL extension vs OpenGL core

    - by user209347
    I was doubting: I'm writing a cross-platform engine OpenGL C++, I figured out windows forces the developers to access OpenGL features above 1.1 through extensions. Now the thing is, on Linux, I know that I can directly access functions if the version supports it through glext.h and opengl version. The problem is that if on Linux, the core doesn't support it, is it possible there is an extensions that supports the same functionality, in my case vertex buffer objects? I'm doing something like this: Windows: (hashdeck) define glFunction functionpointer_to_the_extension (apparently the layout changes font size if I use #) Linux: Since glext already defined glFunction, I can write in client code glFunction, and compile it both on Windows AND Linux without changing a single line in my client code using the engine (my goal). Now the thing is, I saw a tutorial use only the extension on Linux, and not checking for the opengl implementation version. If the functionality is available in the core, is it also available as extension (VBO's e.g.)? Or is an extension something you never know is available? I want to write an engine that gets all the possibilities on hardware, so I need to check (on Linux) for extensions as well as core version for possible functionality implementation.

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  • OpenGL ES 2/3 vs OpenGL 3 (and 4)

    - by Martin Perry
    I have migrated my code from OpenGL ES 2/3 to OpenGL 3 (I added bunch of defines and abstract classes to encapsulate both versions, so I have both in one project and compile only one or another). All I need to change was context initialization and glClearDepth. I dont have any errors. This was kind of strange to me. Even shaders are working correctly (some of them are GL ES 3 - with #version 300 es in their header) Is this a kind of good solution, or should I rewrite something more, before I start adding another functionality like geometry shaders, performance tools etc ?

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  • CRM 2011 - Workflows Vs JavaScripts

    - by Kanini
    In the Contact entity, I have the following attributes Preferred email - A read only field of type Email Personal email 1 - An email field Personal email 2 - An email field Work email 1 - An email field Work email 2 - An email field School email - An email field Other email - An email field Preferred email option - An option set with the following values {Personal email 1, Personal email 2, Work email 1, Work email 2, School email and Other email). None of the above mentioned fields are required. Requirement When user picks a value from Preferred email option, we copy the email address available in that field and apply the same in the Preferred email field. Implementation The Solution Architect suggested that we implement the above requirement as a Workflow. The reason he provided was - most of the times, these values are to be populated by an external website and the data is then fed into CRM 2011 system. So, when they update Preferred email option via a Web Service call to CRM, the WF will run and updated the Preferred email field. My argument / solution What will happen if I do not pick a value from the Preferred email Option Set? Do I set it to any of the email addresses that has a value in it? If so, what if there is more than one of the email address fields are populated, i.e., what if Personal email 1 and Work email 1 is populated but no value is picked in the Option Set? What if a value existed in the Preferred email Option Set and I then change it to NULL? Should the field Preferred email (where the text value of email address is stored) be set to Read Only? If not, what if I have picked Personal email 1 in the Option Set and then edit the Preferred email address text field with a completely new email address If yes, then we are enforcing that the preferred email should be one among Personal email 1, Personal email 2, Work email 1, Work email 2, School email or Other email [My preference would be this] What if I had a value of [email protected] in the personal email 1 field and personal email 2 is empty and choose value of Personal email 1 in the drop down for Preferred email (this will set the Preferred email field to [email protected]) and later, I change the value to Personal email 2 in the Preferred email. It overwrites a valid email address with nothing. I agree that it would be highly unlikely that a user will pick Preferred email as Personal email 2 and not have a value in it but nevertheless it is a possible scenario, isn’t it? What if users typed in a value in Personal email 1 but by mistake picked Personal email 2 in the option set and Personal email 2 field had no value in it. Solution The field Preferred email option should be a required field A JS should run whenever Preferred email option is changed. That JS function should set the relevant email field as required (based on the option chosen) and another JS function should be called (see step 3). A JS function should update the value of Preferred email with the value in the email field (as picked in the option set). The JS function should also be run every time someone updates the actual email field which is chosen in the option set. The guys who are managing the external website should update the Preferred email field - surely, if they can update Preferred email option via a Web Service call, it is easy enough to update the Preferred email right? Question Which is a better method? Should it be written as a JS or a WorkFlow? Also, whose responsibility is it to update the Preferred email field when the data flows from an external website? I am new to CRM 2011 but have around 6 years of experience as a CRM consultant (with other products). I do not come from a development background as I started off as a Application Support Engineer but have picked up development in the last couple of years.

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  • Multi-tenancy - single database vs multiple database

    - by RichardW1001
    We have a number of clients, whose systems share some functionality, but also have quite a degree of diversity. The number of clients is growing - always a healthy thing! - and the diversity between their businesses is also increasing. At present there is a single ASP.Net (Web Forms) Web Site (as opposed to web project), which has sub-folders for each tenant, with that tenant's non-standard pages. There is a separate model project, which deals with database access and business logic. Which is preferable - and most importantly, why - between having (a) 1 database per client, with only the features associated with that client; or (b) a single database shared by all clients, where only a subset of tables are used by any one client. The main concerns within the business are over: maintenance of multiple assets - backups, version control and the like promoting re-use as much as possible How would you ensure these concerns are addressed, which solution is preferable, and why? (I have been also compiling responses to similar questions)

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  • 1 SEO Article Vs 5 SEO Articles?

    You've probably clicked on this article because you think it's a interesting article but the answer seems very easy or straight forward. If you think 5 SEO articles wins or is more beneficial to your business, then your like me.

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  • Older SAS1 hardware Vs. newer SAS2 hardware

    - by user12620172
    I got a question today from someone asking about the older SAS1 hardware from over a year ago that we had on the older 7x10 series. They didn't leave an email so I couldn't respond directly, but I said this blog would be blunt, frank, and open so I have no problem addressing it publicly. A quick history lesson here: When Sun first put out the 7x10 family hardware, the 7410 and 7310 used a SAS1 backend connection to a JBOD that had SATA drives in it. This JBOD was not manufactured by Sun nor did Sun own the IP for it. Now, when Oracle took over, they had a problem with that, and I really can’t blame them. The decision was made to cut off that JBOD and it’s manufacturer completely and use our own where Oracle controlled both the IP and the manufacturing. So in the summer of 2010, the cut was made, and the 7410 and 7310 had a hardware refresh and now had a SAS2 backend going to a SAS2 JBOD with SAS2 drives instead of SATA. This new hardware had two big advantages. First, there was a nice performance increase, mostly due to the faster backend. Even better, the SAS2 interface on the drives allowed for a MUCH faster failover between cluster heads, as the SATA drives were the bottleneck on the older hardware. In September of 2010 there was a major refresh of the rest of the 7000 hardware, the controllers and the other family members, and that’s where we got today’s current line-up of the 7x20 series. So the 7x20 has always used the new trays, and the 7410 and 7310 have used the new SAS2 trays since last July of 2010. Now for the bad news. People who have the 7410 and 7310 from BEFORE the July 2010 cutoff have the models with SAS1 HBAs in them to connect to the older SAS1 trays. Remember, that manufacturer cut all ties with us and stopped making the JBOD, so there’s just no way to get more of them, as they don’t exist. There are some options, however. Oracle support does support taking out the SAS1 HBAs in the old 7410 and 7310 and put in newer SAS2 HBAs which can talk to the new trays. Hey, I didn’t say it was a great option, I just said it’s an option. I fully realize that you would then have a SAS1 JBOD full of SATA drives that you could no longer connect. I do know a client that did this, and took the SAS1 JBOD and connected it to another server and formatted the drives and is using it as a plain, non-7000 JBOD. This is not supported by Oracle support. The other option is to just keep it as-is, as it works just fine, but you just can’t expand it. Then you can get a newer 7x20 series, and use the built-in ZFSSA replication feature to move the data over. Now you can use the newer one for your production data and use the older one for DR, snaps and clones.

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  • ASP.NET 4 Hosting :: ValidateRequest=”false” not working in .Net 4.0 (VS.Net 2010)

    - by mbridge
    When we migrated our project from .NET 3.5 to .NET 4.0, we can get this error: Error: System.Web.HttpRequestValidationException A potentially dangerous Request.Form value was detected from the client (ctl00$CC$txtAnswer=\”… World\r\n\r\nI am doing Testin…\”).”} System.Web.HttpRequestValidationException at System.Web.HttpRequest.ValidateString(String value, String collectionKey, RequestValidationSource requestCollection)    at System.Web.HttpRequest.ValidateNameValueCollection(NameValueCollection nvc, RequestValidationSource requestCollection)    at System.Web.HttpRequest.get_Form()    at System.Web.HttpRequest.get_HasForm()    at System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull)    at System.Web.UI.Page.DeterminePostBackMode()    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)    at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)    at System.Web.UI.Page.ProcessRequest()    at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)    at System.Web.UI.Page.ProcessRequest(HttpContext context)    at ASP.displaypost_aspx.ProcessRequest(HttpContext context) in c:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\a37c2f81\cfc4c927\App_Web_i2rujncl.9.cs:line 0    at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()    at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) What is the Cause? In ASP.NET 4, by default, request validation is enabled for all requests, because it is enabled before the BeginRequest phase of an HTTP request. As a result, request validation applies to requests for all ASP.NET resources, not just .aspx page requests. This includes requests such as Web service calls and custom HTTP handlers. Request validation is also active when custom HTTP modules are reading the contents of an HTTP request. Solution: To revert to the behavior of the ASP.NET 2.0 request validation feature, add the following setting in the Web.config file: <system.web>  <httpRuntime requestValidationMode=”2.0? /> </system.web>

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  • AWStats: Visits from IP address vs Crawlers

    - by user3651934
    I use AWStats in cPanel to see stats of my website. Under Hosts section I see one IP address that has visited 150 pages. I am not sure if one person would have visited 150 pages using a browser. But if these 150 pages have been visited using a software application, then should not it be listed under Robots/Spider section. So how do I determine if I should block a certain IP address that has visited several hundred pages of my website? Thanks

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  • Python vs. Perl in ten years time

    - by Richard
    If you were starting learning a new language today, for scripting and doing "various stuff" with it (from making useful programs to it being glue to several command line programs), would you go with Python or Perl (or some third option, although the battle usually comes to these two)? I've never much used dynamic languages at all, having been able to do everything I needed in traditional static ones. Did some scripting in Perl a couple of years ago, but that was more of a momentary fling, than an attempt to learn it well. Now I've some free time, and have decided to go along with one of these two, and play a little with them. I like Perl's syntax, but Python does seem to be taking rather big steps on overtaking that area. What do you think, which one is more worth learning and why? Also, what do you think, what will be Python's future in about 10 years ... will it overtake Perl and other scripting languages's as a dominant tool for that kind of work (I more often than not find it being implemented in various applications I'm using - for internal scripting and automating loading of data and similar operations), or will it find a balance and coexist along others (Perl)? What is its current "momentum" - does it comes by default with Linux distributions, as Perl does, or does it needs to be installed separately every time? Is it a language which can be expected "to just be there"?

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  • Trade-offs of local vs remote development workflows for a web development team

    - by lamp_scaler
    We currently have SVN setup on a remote development server. Developers SSH into the server and develops on their sandbox environment on the server. Each one has a virtual host pointed to their sandbox so they can preview their changes via the web browser by connecting to developer-sandbox1.domain.com. This has worked well so far because the team is small and everyone uses computers with varying specs and OSs. I've heard some web shops are using a workflow that has the developers work off of a VM on their local machine and then finally push changes to the remote server that hosts SVN. The downside to this is that everyone will need to make sure their machine is powerful enough to run both the VM and all their development tools. This would also mean creating images that mirror the server environment (we use CentOS) and have them install it into their VMs. And this would mean creating new images every time there is an update to the server environment. What are some other trade-offs? Ultimately, why did you choose one workflow over the other?

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  • [News] NHibernate vs MS Entity Framework

    Voil? une question qui se posera de plus en plus avec la sortie prochaine de .NET V4 et Entity Framework V4, l'outil de mapping objet/relationnel de Microsoft. M?me s'il est vrai que l'opinion de Ayende peut para?tre biais?e du fait qu'il est contributeur NHibernate, son point de vue et surtout ses arguments techniques donnent du cr?dit ? ce billet. Il semble aussi que la diff?rence se jouera dans l'outillage, sur ce plan, Entity Framework a pris de l'avance avec la mod?lisation graphique des entit?s. Mais NHibernate est dans ses pas avec Visual NHibernate de l'?diteur Slyce Software.

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  • Best Practices vs Reality

    - by RonHill
    On a scale depicting how closely best practices are followed, with "always" on one end and "never" on the other, my current company falls uncomfortably close to the latter. Just a couple trivial examples: We have no code review process There is very little documentation despite a very large code base (and some of it is blatantly incorrect/misleading) Untested/buggy/uncompilable code is frequently checked in to source control It is comically complicated to create a debuggable build for some of our components because of its underlying architecture. Unhandled exceptions are not uncommon in our releases Empty Catch{ } blocks are everywhere. Now, with the understanding that it's neither practical nor realistic to follow ALL best practices ALL the time, my question is this: How closely have commonly accepted best practices been followed at the companies you've worked for? I'm kind of a noob--this is only the second company I've worked for--so I'm not sure if I'm just more of an anal retentive coder or if I've just ended up at mediocre companies. My guess (hope?) is the latter, but a coworker with way more experience than me says every company he's ever worked for is like this. Given the obvious benefits of following most best practices most of the time, I find it hard to believe it's like this everywhere. Am I wrong?

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  • SQL SERVER – GUID vs INT – Your Opinion

    - by pinaldave
    I think the title is clear what I am going to write in your post. This is age old problem and I want to compile the list stating advantages and disadvantages of using GUID and INT as a Primary Key or Clustered Index or Both (the usual case). Let me start a list by suggesting one advantage and one disadvantage in each case. INT Advantage: Numeric values (and specifically integers) are better for performance when used in joins, indexes and conditions. Numeric values are easier to understand for application users if they are displayed. Disadvantage: If your table is large, it is quite possible it will run out of it and after some numeric value there will be no additional identity to use. GUID Advantage: Unique across the server. Disadvantage: String values are not as optimal as integer values for performance when used in joins, indexes and conditions. More storage space is required than INT. Please note that I am looking to create list of all the generic comparisons. There can be special cases where the stated information is incorrect, feel free to comment on the same. Please leave your opinion and advice in comment section. I will combine a final list and update this blog after a week. By listing your name in post, I will also give due credit. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Constraint and Keys, SQL Data Storage, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • Default vs Impl when implementing interfaces in Java

    - by Gary Rowe
    After reading Should package names be singular or plural? it occurred to me that I've never seen a proper debate covering one of my pet peeves: naming implementations of interfaces. Let's assume that you have a interface Order that is intended to be implemented in a variety of ways but there is only the initial implementation when the project is first created. Do you go for DefaultOrder or OrderImpl or some other variant to avoid the false dichotomy? And what do you do when more implementations come along? And most important... why?

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  • Validation does not work when I use Validator.TryValidateObject.

    - by ashraf
    DataAnnotations does not work with buddy class. The following code always validate true. Why ? var isValid = Validator.TryValidateObject(new Customer(), Context, results, true); and here is the buddy class. public partial class Customer { public string Name { get; set; } public int Age { get; set; } } [MetadataType(typeof(CustomerMetaData))] public partial class Customer { public class CustomerMetaData { [Required(ErrorMessage = "You must supply a name for a customer.")] public string Name { get; set; } } } Here is another thread with same question., but no answer. link text

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