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  • Multiple Monitors on One Screen

    - by Hulihan Applications
    Does anyone know of any software/hardware configuration that will allow you to preview/view the contents multiple monitors on one monitor? Let's pretend: I have two monitors hooked up to one pc, Monitor A and Monitor B. The monitors are not near each other. I'd like to be able to preview/see what's displaying on Monitor B on Monitor A I haven't been able to find much about this, but I imagine it may not currently be possible to access/emulate video output going out of a video port in software. However, wouldn't it be possible to capture display data generated by the OS kernel or data getting passed down to the display adapter driver?

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  • Can htpasswd be used to restrict access to a URL rather than a specific folder?

    - by me_here
    I would like to restrict access to certain URLs with htpasswd files, rather than folders, is this possible? For example, I wish to restrict the URL: www.example.com/pages/id/227/Restricted_Page But allow access to other URLs such as: www.example.com/pages/id/100/Normal_Page Is this possible? The "pages" part of the url refers to a pages.php file, and the "id" part is the function name in that file. The reason for wanting to do this is because of migrating existing restrict lists, in the form of htpasswd files from another site. Many thanks.

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  • Apache Rewrite Rules

    - by Philip
    I have moved my website from a Wiki to Wordpress and in the process, realised that I have broken links to some popular pages on my website. Is it possible to fix this with a rewrite rule? I need the rule to redirect anything beginning with "^/wiki/(.+)$" to "/$1" but also replacing the "_" character used in MediaWiki slugs to "-" used in Wordpress slugs. For example: http://example.com/wiki/An_Example_Page should be pointed to: http://example.com/an-example-page Is it possible to write such a rewrite rule? Edit: It appears that Wordpress doesn't even care if the "/wiki/" part is removed - provided the slug matches, and that seems to be case-insensitive too. So all I need to do is change the "_" characters to "-" in the slugs.

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  • Snowfall application with Windows 7 compatibility

    - by Shiki
    Okay, this may seem to be a strange question. I'm searching for a 'snowfall application'. Back then we had a lot of like this.. in the old ages, when XP came out, so on. Nowadays, I can't find a single working one. It's not like I suddenly want something like this, but a girl asked me whethers its possible or not. IMHO its possible but... Please help me out. =) (Obviously, free software shareware.)

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  • How to autostart service in ANY linux?

    - by user329115
    I need to install the dumbest possible service (a binary) and have it reliably run as the current user at boot (or login, whatever) at as many platforms as possible (of the aging point-of-sale type). The app monitors another archives generated by another app in the user-session. Startup alternatives considered: init.d @reboot in crontab a .desktop file in ~/.config/autostart a myriad of other solutions including .profile and .bashrc All of the above break down at some point. The problems stem from not wanting to run as root (I want the files generated to be user-accessible), and not having a way to reliably get the current user name in sudo on all platforms. Ideally not even sudo can be assumed available. Hey, I just want to run something on boot and I have "root" power to do so. Windows get the job done easily enough. This isn't rocket science, is it?

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  • How to move a Windows instance to a different EC2 data centre?

    - by Darren Cook
    I've a Windows EC2 instance running in one region and need to move it to another region (Tokyo and Singapore in this case). Is that even possible? What potential problems do I need to watch out for? (I found http://stackoverflow.com/questions/2181849/ec2-instance-cloning which is describing how to do it, but appears to assume Linux instances, and to assume the same data centre. Is it possible to move my keys across to another region?) I tried something similar with a Windows instance a few months ago, just trying to clone it in the same data centre, but I couldn't get it working quickly, so I had to give up and just create a fresh instance at that time. This time I've got a bit of breathing space, and want to research how to do it properly! Root Device Type: ebs Block Devices: sda1 xvdf (both are ebs, "attached", and have Delete on termination set to "no"; sda1 is the root device) The AMI is described as "Unavailable" (then an ami number).

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  • Remote Linux system via Windows 7

    - by kaila
    I have a dual boot with Windows 7 and Fedora. Though I can long into both without any problems, I am trying to log in to the linux account via the Windows account. Is that possible? Or, is it possible to access my university's linux server via telnet from home? I did so and got an error, with cold not connect to port 23 message. Also, since most of my mail accounts are on Windows, the passwords to which I have forgotten, I would prefer working on a ;remote' connection.

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  • Can anyone suggest me game recorder software for Youtube Video? [closed]

    - by Sukhdev Taneja
    I am looking for game recorder software to capture movies of PC games (with sound) so that I can upload to YouTube Videos. I have recorded some games on my computer. But they run so quickly and fast. Can anybody suggest me any computer screen recorder (with sound) so that I can make my own computer gameplay trailer for Youtube. Is it possible to record PS2 games too without using any TV Tuner Card on computer. Please suggest any freeware software if possible for my purpose. Thanks.

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  • How do I make two different Google Chrome profiles?

    - by ldigas
    I have a laptop which I use for (the major part) of my work and private life, and would like to set those two apart starting with Google Chrome. So far, my Google Chrome contains my work bookmarks, logins/passwords and everything else ... which I use for work, which I use privately, which I use in my spare time (funny Youtube videos, what else :) Is it possible to define multiple Google Chrome profiles, let's say work and free-time, so one can quickly switch between them, where bookmarks, logins and so on, from one would be invisible in the other, and vice versa? Also, is it possible to put them into some directory different from the default, so one can easily backup them, when needed? If it is, could anyone describe it in simple terms, or his experiences if she/he has a better way of going about this?

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  • Server over VPN?

    - by zib_redlektab
    I don't know that much about VPN, so it could be that this is utterly impossible. Here's hoping, though. I would like to forward a port from my router to a machine connected to the network via VPN. That way, I could run a simple server on my laptop, and it would continue to work at the same address no matter where I am. The trick is that I don't want people connecting to the server to have to join the VPN. It should be completely transparent to the end-user. If it's not possible with VPN, is there some other technology that would make this possible? Basically just forwarding a port to a remote machine, one without a static IP.

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  • How can I dynamically change auto complete entries in a C# combobox or textbox?

    - by Sam Hopkins
    I have a combobox in C# and I want to use auto complete suggestions with it, however I want to be able to change the auto complete entries as the user types, because the possible valid entries are far too numerous to populate the AutoCompleteStringCollection at startup. As an example, suppose I'm letting the user type in a name. I have a list of possible first names ("Joe", "John") and a list of surnames ("Bloggs", "Smith"), but if I have a thousand of each, then that would be a million possible strings - too many to put in the auto complete entries. So initially I want to have just the first names as suggestions ("Joe", "John") , and then once the user has typed the first name, ("Joe"), I want to remove the existing auto complete entries and replace them with a new set consisting of the chosen first name followed by the possible surnames ("Joe Bloggs", "Joe Smith"). In order to do this, I tried the following code: void InitializeComboBox() { ComboName.AutoCompleteMode = AutoCompleteMode.SuggestAppend; ComboName.AutoCompleteSource = AutoCompleteSource.CustomSource; ComboName.AutoCompleteCustomSource = new AutoCompleteStringCollection(); ComboName.TextChanged += new EventHandler( ComboName_TextChanged ); } void ComboName_TextChanged( object sender, EventArgs e ) { string text = this.ComboName.Text; string[] suggestions = GetNameSuggestions( text ); this.ComboQuery.AutoCompleteCustomSource.Clear(); this.ComboQuery.AutoCompleteCustomSource.AddRange( suggestions ); } However, this does not work properly. It seems that the call to Clear() causes the auto complete mechanism to "turn off" until the next character appears in the combo box, but of course when the next character appears the above code calls Clear() again, so the user never actually sees the auto complete functionality. It also causes the entire contents of the combo box to become selected, so between every keypress you have to deselect the existing text, which makes it unusable. If I remove the call to Clear() then the auto complete works, but it seems that then the AddRange() call has no effect, because the new suggestions that I add do not appear in the auto complete dropdown. I have been searching for a solution to this, and seen various things suggested, but I cannot get any of them to work - either the auto complete functionality appears disabled, or new strings do not appear. Here is a list of things I have tried: Calling BeginUpdate() before changing the strings and EndUpdate() afterwards. Calling Remove() on all the existing strings instead of Clear(). Clearing the text from the combobox while I update the strings, and adding it back afterwards. Setting the AutoCompleteMode to "None" while I change the strings, and setting it back to "SuggestAppend" afterwards. Hooking the TextUpdate or KeyPress event instead of TextChanged. Replacing the existing AutoCompleteCustomSource with a new AutoCompleteStringCollection each time. None of these helped, even in various combinations. Spence suggested that I try overriding the ComboBox function that gets the list of strings to use in auto complete. Using a reflector I found a couple of methods in the ComboBox class that look promising - GetStringsForAutoComplete() and SetAutoComplete(), but they are both private so I can't access them from a derived class. I couldn't take that any further. I tried replacing the ComboBox with a TextBox, because the auto complete interface is the same, and I found that the behaviour is slightly different. With the TextBox it appears to work better, in that the Append part of the auto complete works properly, but the Suggest part doesn't - the suggestion box briefly flashes to life but then immediately disappears. So I thought "Okay, I'll

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  • Correct XML serialization and deserialization of "mixed" types in .NET

    - by Stefan
    My current task involves writing a class library for processing HL7 CDA files. These HL7 CDA files are XML files with a defined XML schema, so I used xsd.exe to generate .NET classes for XML serialization and deserialization. The XML Schema contains various types which contain the mixed="true" attribute, specifying that an XML node of this type may contain normal text mixed with other XML nodes. The relevant part of the XML schema for one of these types looks like this: <xs:complexType name="StrucDoc.Paragraph" mixed="true"> <xs:sequence> <xs:element name="caption" type="StrucDoc.Caption" minOccurs="0"/> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element name="br" type="StrucDoc.Br"/> <xs:element name="sub" type="StrucDoc.Sub"/> <xs:element name="sup" type="StrucDoc.Sup"/> <!-- ...other possible nodes... --> </xs:choice> </xs:sequence> <xs:attribute name="ID" type="xs:ID"/> <!-- ...other attributes... --> </xs:complexType> The generated code for this type looks like this: /// <remarks/> [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(TypeName="StrucDoc.Paragraph", Namespace="urn:hl7-org:v3")] public partial class StrucDocParagraph { private StrucDocCaption captionField; private object[] itemsField; private string[] textField; private string idField; // ...fields for other attributes... /// <remarks/> public StrucDocCaption caption { get { return this.captionField; } set { this.captionField = value; } } /// <remarks/> [System.Xml.Serialization.XmlElementAttribute("br", typeof(StrucDocBr))] [System.Xml.Serialization.XmlElementAttribute("sub", typeof(StrucDocSub))] [System.Xml.Serialization.XmlElementAttribute("sup", typeof(StrucDocSup))] // ...other possible nodes... public object[] Items { get { return this.itemsField; } set { this.itemsField = value; } } /// <remarks/> [System.Xml.Serialization.XmlTextAttribute()] public string[] Text { get { return this.textField; } set { this.textField = value; } } /// <remarks/> [System.Xml.Serialization.XmlAttributeAttribute(DataType="ID")] public string ID { get { return this.idField; } set { this.idField = value; } } // ...properties for other attributes... } If I deserialize an XML element where the paragraph node looks like this: <paragraph>first line<br /><br />third line</paragraph> The result is that the item and text arrays are read like this: itemsField = new object[] { new StrucDocBr(), new StrucDocBr(), }; textField = new string[] { "first line", "third line", }; From this there is no possible way to determine the exact order of the text and the other nodes. If I serialize this again, the result looks exactly like this: <paragraph> <br /> <br />first linethird line </paragraph> The default serializer just serializes the items first and then the text. I tried implementing IXmlSerializable on the StrucDocParagraph class so that I could control the deserialization and serialization of the content, but it's rather complex since there are so many classes involved and I didn't come to a solution yet because I don't know if the effort pays off. Is there some kind of easy workaround to this problem, or is it even possible by doing custom serialization via IXmlSerializable? Or should I just use XmlDocument or XmlReader/XmlWriter to process these documents?

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  • Is this a right way to use NHibernate?

    - by Venemo
    I spent the rest of the evening reading StackOverflow questions and also some blog entries and links about the subject. All of them turned out to be very helpful, but I still feel that they don't really answer my question. So, I'm developing a simple web application. I'd like to create a reusable data access layer which I can later reuse in other solutions. 99% of these will be web applications. This seems to be a good excuse for me to learn NHibernate and some of the patterns around it. My goals are the following: I don't want the business logic layer to know ANYTHING about the inner workings of the database, nor NHibernate itself. I want the business logic layer to have the least possible number of assumptions about the data access layer. I want the data access layer as simplistic and easy-to-use as possible. This is going to be a simple project, so I don't want to overcomplicate anything. I want the data access layer to be as non-intrusive as possible. Will all this in mind, I decided to use the popular repository pattern. I read about this subject on this site and on various dev blogs, and I heard some stuff about the unit of work pattern. I also looked around and checked out various implementations. (Including FubuMVC contrib, and SharpArchitecture, and stuff on some blogs.) I found out that most of these operate with the same principle: They create a "unit of work" which is instantiated when a repository is instantiated, they start a transaction, do stuff, and commit, and then start all over again. So, only one ISession per Repository and that's it. Then the client code needs to instantiate a repository, do stuff with it, and then dispose. This usage pattern doesn't meet my need of being as simplistic as possible, so I began thinking about something else. I found out that NHibernate already has something which makes custom "unit of work" implementations unnecessary, and that is the CurrentSessionContext class. If I configure the session context correctly, and do the clean up when necessary, I'm good to go. So, I came up with this: I have a static class called NHibernateHelper. Firstly, it has a static property called CurrentSessionFactory, which upon first call, instantiates a session factory and stores it in a static field. (One ISessionFactory per one AppDomain is good enough.) Then, more importantly, it has a CurrentSession static property, which checks if there is an ISession bound to the current session context, and if not, creates one, and binds it, and it returns with the ISession bound to the current session context. Because it will be used mostly with WebSessionContext (so, one ISession per HttpRequest, although for the unit tests, I configured ThreadStaticSessionContext), it should work seamlessly. And after creating and binding an ISession, it hooks an event handler to the HttpContext.Current.ApplicationInstance.EndRequest event, which takes care of cleaning up the ISession after the request ends. (Of course, it only does this if it is really running in a web environment.) So, with all this set up, the NHibernateHelper will always be able to return a valid ISession, so there is no need to instantiate a Repository instance for the "unit of work" to operate properly. Instead, the Repository is a static class which operates with the ISession from the NHibernateHelper.CurrentSession property, and exposes some functionality through that. I'm curious, what do you think about this? Is it a valid way of thinking, or am I completely off track here?

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  • Lightweight use of Enterprise Library TraceListeners

    - by gWiz
    Is it possible to use the Enterprise Library 4.1 TraceListeners without using the entire Enterprise Library Logging AB? I'd prefer to simply use .NET Diagnostics Tracing, but would like to setup a listener that sends emails on Error events. I figured I could use the Enterprise Library EmailTraceListener. However, my initial attempts to configure it have failed. Here's what I hoped would work: <system.diagnostics> <trace autoflush="false" /> <sources> <source name="SampleSource" switchValue="Verbose" > <listeners> <add name="textFileListener" /> <add name="emailListener" /> </listeners> </source> </sources> <sharedListeners> <add name="textFileListener" type="System.Diagnostics.TextWriterTraceListener" initializeData="..\trace.log" traceOutputOptions="DateTime"> <filter type="System.Diagnostics.EventTypeFilter" initializeData="Verbose" /> </add> <add name="emailListener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.EmailTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging" toAddress="[email protected]" fromAddress="[email protected]" smtpServer="mail.example.com" > <filter type="System.Diagnostics.EventTypeFilter" initializeData="Verbose" /> </add> </sharedListeners> </system.diagnostics> However I get [ArgumentException: The parameter 'address' cannot be an empty string. Parameter name: address] System.Net.Mail.MailAddress..ctor(String address, String displayName, Encoding displayNameEncoding) +1098157 System.Net.Mail.MailAddress..ctor(String address) +8 Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.EmailMessage.CreateMailMessage() +256 Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.EmailMessage.Send() +39 Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.EmailTraceListener.Write(String message) +96 System.Diagnostics.TraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id) +184 System.Diagnostics.TraceListener.TraceEvent(TraceEventCache eventCache, String source, TraceEventType eventType, Int32 id, String format, Object[] args) +63 System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String format, Object[] args) +198 System.Diagnostics.TraceSource.TraceInformation(String message) +14 Which leads me to believe the .NET Tracing code does not care about the "non-standard" config attributes I've supplied for emailListener. I also tried adding the appropriate LAB configSection declaration and: <loggingConfiguration> <listeners> <add toAddress="[email protected]" fromAddress="[email protected]" smtpServer="mail.example.com" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.EmailTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging" name="emailListener" /> </listeners> </loggingConfiguration> This also results in the same exception. I figure it's possible to programmatically configure the EmailTraceListener, but I prefer this to be config-driven. I also understand I can implement my own derivative of TraceListener. So, is it possible to use the Ent Lib TraceListeners, without using the whole Ent Lib LAB, and configure them from the config file? Update: After examining the code, I have discovered it is not possible. The Ent Lib TraceListeners do not actually utilize the config attributes they specify in overriding TraceListener.GetSupportedAttributes(), despite the recommendations in the .NET TraceListener documentation. Bug filed.

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  • How to design a C / C++ library to be usable in many client languages?

    - by Brian Schimmel
    I'm planning to code a library that should be usable by a large number of people in on a wide spectrum of platforms. What do I have to consider to design it right? To make this questions more specific, there are four "subquestions" at the end. Choice of language Considering all the known requirements and details, I concluded that a library written in C or C++ was the way to go. I think the primary usage of my library will be in programs written in C, C++ and Java SE, but I can also think of reasons to use it from Java ME, PHP, .NET, Objective C, Python, Ruby, bash scrips, etc... Maybe I cannot target all of them, but if it's possible, I'll do it. Requirements It would be to much to describe the full purpose of my library here, but there are some aspects that might be important to this question: The library itself will start out small, but definitely will grow to enormous complexity, so it is not an option to maintain several versions in parallel. Most of the complexity will be hidden inside the library, though The library will construct an object graph that is used heavily inside. Some clients of the library will only be interested in specific attributes of specific objects, while other clients must traverse the object graph in some way Clients may change the objects, and the library must be notified thereof The library may change the objects, and the client must be notified thereof, if it already has a handle to that object The library must be multi-threaded, because it will maintain network connections to several other hosts While some requests to the library may be handled synchronously, many of them will take too long and must be processed in the background, and notify the client on success (or failure) Of course, answers are welcome no matter if they address my specific requirements, or if they answer the question in a general way that matters to a wider audience! My assumptions, so far So here are some of my assumptions and conclusions, which I gathered in the past months: Internally I can use whatever I want, e.g. C++ with operator overloading, multiple inheritance, template meta programming... as long as there is a portable compiler which handles it (think of gcc / g++) But my interface has to be a clean C interface that does not involve name mangling Also, I think my interface should only consist of functions, with basic/primitive data types (and maybe pointers) passed as parameters and return values If I use pointers, I think I should only use them to pass them back to the library, not to operate directly on the referenced memory For usage in a C++ application, I might also offer an object oriented interface (Which is also prone to name mangling, so the App must either use the same compiler, or include the library in source form) Is this also true for usage in C# ? For usage in Java SE / Java EE, the Java native interface (JNI) applies. I have some basic knowledge about it, but I should definitely double check it. Not all client languages handle multithreading well, so there should be a single thread talking to the client For usage on Java ME, there is no such thing as JNI, but I might go with Nested VM For usage in Bash scripts, there must be an executable with a command line interface For the other client languages, I have no idea For most client languages, it would be nice to have kind of an adapter interface written in that language. I think there are tools to automatically generate this for Java and some others For object oriented languages, it might be possible to create an object oriented adapter which hides the fact that the interface to the library is function based - but I don't know if its worth the effort Possible subquestions is this possible with manageable effort, or is it just too much portability? are there any good books / websites about this kind of design criteria? are any of my assumptions wrong? which open source libraries are worth studying to learn from their design / interface / souce? meta: This question is rather long, do you see any way to split it into several smaller ones? (If you reply to this, do it as a comment, not as an answer)

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  • SQL SERVER – Generate Report for Index Physical Statistics – SSMS

    - by pinaldave
    Few days ago, I wrote about SQL SERVER – Out of the Box – Activity and Performance Reports from SSSMS (Link). A user asked me a question regarding if we can use similar reports to get the detail about Indexes. Yes, it is possible to do the same. There are similar type of reports are available at Database level, just like those available at the Server Instance level. You can right click on Database name and click Reports. Under Standard Reports, you will find following reports. Disk Usage Disk Usage by Top Tables Disk Usage by Table Disk Usage by Partition Backup and Restore Events All Transactions All Blocking Transactions Top Transactions by Age Top Transactions by Blocked Transactions Count Top Transactions by Locks Count Resource Locking Statistics by Objects Object Execute Statistics Database Consistency history Index Usage Statistics Index Physical Statistics Schema Change history User Statistics Select the Reports with name Index Physical Statistics. Once click, a report containing all the index names along with other information related to index will be visible, e.g. Index Type and number of partitions. One column that caught my interest was Operation Recommended. In some place, it suggested that index needs to be rebuilt. It is also possible to click and expand the column of partitions and see additional details about index as well. DBA and Developers who just want to have idea about how your index is and its physical statistics can use this tool. Click to Enlarge Note: Please note that I will rebuild my indexes just because this report is recommending it. There are many other parameters you need to consider before rebuilding indexes. However, this tool gives you the accurate stats of your index and it can be right away exported to Excel or PDF writing by clicking on the report. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • Parallelism in .NET – Part 3, Imperative Data Parallelism: Early Termination

    - by Reed
    Although simple data parallelism allows us to easily parallelize many of our iteration statements, there are cases that it does not handle well.  In my previous discussion, I focused on data parallelism with no shared state, and where every element is being processed exactly the same. Unfortunately, there are many common cases where this does not happen.  If we are dealing with a loop that requires early termination, extra care is required when parallelizing. Often, while processing in a loop, once a certain condition is met, it is no longer necessary to continue processing.  This may be a matter of finding a specific element within the collection, or reaching some error case.  The important distinction here is that, it is often impossible to know until runtime, what set of elements needs to be processed. In my initial discussion of data parallelism, I mentioned that this technique is a candidate when you can decompose the problem based on the data involved, and you wish to apply a single operation concurrently on all of the elements of a collection.  This covers many of the potential cases, but sometimes, after processing some of the elements, we need to stop processing. As an example, lets go back to our previous Parallel.ForEach example with contacting a customer.  However, this time, we’ll change the requirements slightly.  In this case, we’ll add an extra condition – if the store is unable to email the customer, we will exit gracefully.  The thinking here, of course, is that if the store is currently unable to email, the next time this operation runs, it will handle the same situation, so we can just skip our processing entirely.  The original, serial case, with this extra condition, might look something like the following: foreach(var customer in customers) { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { // Exit gracefully if we fail to email, since this // entire process can be repeated later without issue. if (theStore.EmailCustomer(customer) == false) break; customer.LastEmailContact = DateTime.Now; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, we’re processing our loop, but at any point, if we fail to send our email successfully, we just abandon this process, and assume that it will get handled correctly the next time our routine is run.  If we try to parallelize this using Parallel.ForEach, as we did previously, we’ll run into an error almost immediately: the break statement we’re using is only valid when enclosed within an iteration statement, such as foreach.  When we switch to Parallel.ForEach, we’re no longer within an iteration statement – we’re a delegate running in a method. This needs to be handled slightly differently when parallelized.  Instead of using the break statement, we need to utilize a new class in the Task Parallel Library: ParallelLoopState.  The ParallelLoopState class is intended to allow concurrently running loop bodies a way to interact with each other, and provides us with a way to break out of a loop.  In order to use this, we will use a different overload of Parallel.ForEach which takes an IEnumerable<T> and an Action<T, ParallelLoopState> instead of an Action<T>.  Using this, we can parallelize the above operation by doing: Parallel.ForEach(customers, (customer, parallelLoopState) => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { // Exit gracefully if we fail to email, since this // entire process can be repeated later without issue. if (theStore.EmailCustomer(customer) == false) parallelLoopState.Break(); else customer.LastEmailContact = DateTime.Now; } }); There are a couple of important points here.  First, we didn’t actually instantiate the ParallelLoopState instance.  It was provided directly to us via the Parallel class.  All we needed to do was change our lambda expression to reflect that we want to use the loop state, and the Parallel class creates an instance for our use.  We also needed to change our logic slightly when we call Break().  Since Break() doesn’t stop the program flow within our block, we needed to add an else case to only set the property in customer when we succeeded.  This same technique can be used to break out of a Parallel.For loop. That being said, there is a huge difference between using ParallelLoopState to cause early termination and to use break in a standard iteration statement.  When dealing with a loop serially, break will immediately terminate the processing within the closest enclosing loop statement.  Calling ParallelLoopState.Break(), however, has a very different behavior. The issue is that, now, we’re no longer processing one element at a time.  If we break in one of our threads, there are other threads that will likely still be executing.  This leads to an important observation about termination of parallel code: Early termination in parallel routines is not immediate.  Code will continue to run after you request a termination. This may seem problematic at first, but it is something you just need to keep in mind while designing your routine.  ParallelLoopState.Break() should be thought of as a request.  We are telling the runtime that no elements that were in the collection past the element we’re currently processing need to be processed, and leaving it up to the runtime to decide how to handle this as gracefully as possible.  Although this may seem problematic at first, it is a good thing.  If the runtime tried to immediately stop processing, many of our elements would be partially processed.  It would be like putting a return statement in a random location throughout our loop body – which could have horrific consequences to our code’s maintainability. In order to understand and effectively write parallel routines, we, as developers, need a subtle, but profound shift in our thinking.  We can no longer think in terms of sequential processes, but rather need to think in terms of requests to the system that may be handled differently than we’d first expect.  This is more natural to developers who have dealt with asynchronous models previously, but is an important distinction when moving to concurrent programming models. As an example, I’ll discuss the Break() method.  ParallelLoopState.Break() functions in a way that may be unexpected at first.  When you call Break() from a loop body, the runtime will continue to process all elements of the collection that were found prior to the element that was being processed when the Break() method was called.  This is done to keep the behavior of the Break() method as close to the behavior of the break statement as possible. We can see the behavior in this simple code: var collection = Enumerable.Range(0, 20); var pResult = Parallel.ForEach(collection, (element, state) => { if (element > 10) { Console.WriteLine("Breaking on {0}", element); state.Break(); } Console.WriteLine(element); }); If we run this, we get a result that may seem unexpected at first: 0 2 1 5 6 3 4 10 Breaking on 11 11 Breaking on 12 12 9 Breaking on 13 13 7 8 Breaking on 15 15 What is occurring here is that we loop until we find the first element where the element is greater than 10.  In this case, this was found, the first time, when one of our threads reached element 11.  It requested that the loop stop by calling Break() at this point.  However, the loop continued processing until all of the elements less than 11 were completed, then terminated.  This means that it will guarantee that elements 9, 7, and 8 are completed before it stops processing.  You can see our other threads that were running each tried to break as well, but since Break() was called on the element with a value of 11, it decides which elements (0-10) must be processed. If this behavior is not desirable, there is another option.  Instead of calling ParallelLoopState.Break(), you can call ParallelLoopState.Stop().  The Stop() method requests that the runtime terminate as soon as possible , without guaranteeing that any other elements are processed.  Stop() will not stop the processing within an element, so elements already being processed will continue to be processed.  It will prevent new elements, even ones found earlier in the collection, from being processed.  Also, when Stop() is called, the ParallelLoopState’s IsStopped property will return true.  This lets longer running processes poll for this value, and return after performing any necessary cleanup. The basic rule of thumb for choosing between Break() and Stop() is the following. Use ParallelLoopState.Stop() when possible, since it terminates more quickly.  This is particularly useful in situations where you are searching for an element or a condition in the collection.  Once you’ve found it, you do not need to do any other processing, so Stop() is more appropriate. Use ParallelLoopState.Break() if you need to more closely match the behavior of the C# break statement. Both methods behave differently than our C# break statement.  Unfortunately, when parallelizing a routine, more thought and care needs to be put into every aspect of your routine than you may otherwise expect.  This is due to my second observation: Parallelizing a routine will almost always change its behavior. This sounds crazy at first, but it’s a concept that’s so simple its easy to forget.  We’re purposely telling the system to process more than one thing at the same time, which means that the sequence in which things get processed is no longer deterministic.  It is easy to change the behavior of your routine in very subtle ways by introducing parallelism.  Often, the changes are not avoidable, even if they don’t have any adverse side effects.  This leads to my final observation for this post: Parallelization is something that should be handled with care and forethought, added by design, and not just introduced casually.

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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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  • Podcast: The Invisible UI : Natural User Interfaces with Josh Blake

    - by craigshoemaker
    Josh Blake of Infostrat joins Pixel8 to discuss NUI development in .NET. Josh is the author of the upcoming book Multitouch on Windows from Manning. Reaching far beyond theory and the niche market of Microsoft Surface, NUI development is now possible with Silverlight and WPF development on Windows 7 and Windows 7 Mobile devices. Subscribe to the podcast! The Natural User Interface (NUI) was a prominent force at MIX10. What is NUI? Wikipedia defines it as: Natural user interface, or NUI, is the common parlance used by designers and developers of computer interfaces to refer to a user interface that is effectively invisible, or becomes invisible with successive learned interactions, to its users. The word natural is used because most computer interfaces use artificial control devices whose operation has to be learned. A NUI relies on a user being able to carry out relatively natural motions, movements or gestures that they quickly discover control the computer application or manipulate the on-screen content. The most descriptive identifier of a NUI is the lack of a physical keyboard and/or mouse. In our interview Josh demystifies what NUI is, makes a distinction between gestures and manipulations, and talks about what is possible today for NUI development. For more from Josh make sure to check out his book: and watch his MIX Presentation: Developing Natural User Interfaces with Microsoft Silverlight and WPF 4 Touch Resources Mentioned in the Show Check out the following videos that show the roots and future of NUI development: Jeff Han's Multi-Touch TED Presentation Microsoft Surface Project Natal MIX10 Day 2 Keynote A few times during our talk Bill Buxton’s work is mentioned. To see his segment of the MIX10 day 2 keynote, click below:

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  • Forum software advice needed

    - by David Thompson
    Hello All ... we want to migrate our sites current forum (proprietary built) to a newer, more modern (feature rich) platform. I've been looking around at the available options and have narrowed it down to vBulletin, Vanilla or Phorum (unless you have another suggestion ?). I hope someone here can give me some feedback on their experiences either migrating to a new forum or working deeply with one. The current forum we have has approx 2.2 million threads in it and is contained in a MySQL database. Data Migration is obviously the first issue, is one of the major Forum vendors better or worse in this regard ? The software needs to be able to be clustered and cached to ensure availability and performance. We want it to be PHP based and store it's data in MySQL. The code needs to be open to allow us to highly customise the software both to strip out a lot of stuff and be able to integrate our sites features. A lot of the forums I've looked at have a lot of duplicate features to our main site, in particular member management, profiles etc. I realise we'll have to do a good bit of development in removing these and tieing it all back to the main site so we want to find a platform that makes this kind of integration as easy as possible. Finally I guess if 'future proofing' the forum (as best as possible) given the above. Which platform will allow us to customise it but also allow us to keep instep with upgrades. Which forum software has the best track record for bringing online new features in a timely manner ? etc. etc. I know it's a big question but if anyone here has any experience in some or all of the above I'd be very grateful.

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  • List of resources for database continuous integration

    - by David Atkinson
    Because there is so little information on database continuous integration out in the wild, I've taken it upon myself to aggregate as much as possible and post the links to this blog. Because it's my area of expertise, this will focus on SQL Server and Red Gate tooling, although I am keen to include any quality articles that discuss the topic in general terms. Please let me know if you find a resource that I haven't listed! General database Continuous Integration · What is Database Continuous Integration? (David Atkinson) · Continuous Integration for SQL Server Databases (Troy Hunt) · Installing NAnt to drive database continuous integration (David Atkinson) · Continuous Integration Tip #3 - Version your Databases as part of your automated build (Doug Rathbone) · How the "migrations" approach makes database continuous integration possible (David Atkinson) · Continuous Integration for the Database (Keith Bloom) Setting up Continuous Integration with Red Gate tools · Continuous integration for databases using Red Gate tools - A technical overview (White Paper, Roger Hart and David Atkinson) · Continuous integration for databases using Red Gate SQL tools (Product pages) · Database continuous integration step by step (David Atkinson) · Database Continuous Integration with Red Gate Tools (video, David Atkinson) · Database schema synchronisation with RedGate (Vincent Brouillet) · Database continuous integration and deployment with Red Gate tools (David Duffett) · Automated database releases with TeamCity and Red Gate (Troy Hunt) · How to build a database from source control (David Atkinson) · Continuous Integration Automated Database Update Process (Lance Lyons) Other · Evolutionary Database Design (Martin Fowler) · Recipes for Continuous Database Integration: Evolutionary Database Development (book, Pramod J Sadalage) · Recipes for Continuous Database Integration (book, Pramod Sadalage) · The Red Gate Guide to SQL Server Team-based Development (book, Phil Factor, Grant Fritchey, Alex Kuznetsov, Mladen Prajdic) · Using SQL Test Database Unit Testing with TeamCity Continuous Integration (Dave Green) · Continuous Database Integration (covers MySQL, Perason Education) Technorati Tags: SQL Server,Continous Integration

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