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• Seeking advice on system documentation

  - by Shadders

  I have a rating engine (it is basically an algorithm) which when I started had no formal documentation. We have created a functional specification/decomposition which is our business level document but now I need something more technical (a technical specification). What I am struggling to understand is what that document looks like, what format it should be in and to what level of detail we should go into. We are in the process of commenting all of the code. We also have a rough document called a Blueprint which reflects the flow of the model and is written in pseudo code. Is the combination of this blueprint and the model comments sufficient as a Technical Specification?

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• Sending JSON to an ASP.NET MVC Action Method Argument

  Javier G Money Lozano, one of the good folks involved with C4MVC, recently wrote a blog post on posting JSON (JavaScript Object Notation) encoded data to an MVC controller action. In his post, he describes an interesting approach of using a custom model binder to bind sent JSON data to an argument of an action method. Unfortunately, his sample left out the custom model binder and only demonstrates how to retrieve JSON data sent from a controller action, not how to send the JSON to the action method....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Page Load Time - "Waiting on..." taking ages. What part of page request process is hung?

  - by James

  I have a new cluster site running on Magento that's on a development server that is made up of 2 x web servers and 1 x database server. I have optimized the site in all areas I know (gzip, increasing php memory limits, increasing database memory limits etc) but sometimes the page loading gets stuck on 'waiting for xxx.xx.xx.xxx' (Chrome and other broswers, chrome just shows it that way). It can sit there for 40 + seconds, sometimes it just never loads and I close it in frustration. What part of the page loading process is this hung at? Is it a server issue, database issue, platform issue? I need to know where to start or whether to push the hosting provider about it.

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• WMemoryProfiler is Released

  - by Alois Kraus

  What is it? WMemoryProfiler is a managed profiling Api to aid integration testing. This free library can get managed heap statistics and memory usage for your own process (remember testing) and other processes as well. The best thing is that it does work from .NET 2.0 up to .NET 4.5 in x86 and x64. To make it more interesting it can attach to any running .NET process. The reason why I do mention this is that commercial profilers do support this functionality only for their professional editions. An normally only since .NET 4.0 since the profiling API only since then does support attaching to a running process. This thing does differ in many aspects from “normal” profilers because while profiling yourself you can get all objects from all managed heaps back as an object array. If you ever wanted to change the state of an object which does only exist a method local in another thread you can get your hands on it now … Enough theory. Show me some code /// <summary> /// Show feature to not only get statisics out of a process but also the newly allocated /// instances since the last call to MarkCurrentObjects. /// GetNewObjects does return the newly allocated objects as object array /// </summary> static void InstanceTracking() { using (var dumper = new MemoryDumper()) // if you have problems use to see the debugger windows true,true)) { dumper.MarkCurrentObjects(); Allocate(); ILookup<Type, object> newObjects = dumper.GetNewObjects() .ToLookup( x => x.GetType() ); Console.WriteLine("New Strings:"); foreach (var newStr in newObjects[typeof(string)] ) { Console.WriteLine("Str: {0}", newStr); } } } … New Strings: Str: qqd Str: String data: Str: String data: 0 Str: String data: 1 … This is really hot stuff. Not only you can get heap statistics but you can directly examine the new objects and make queries upon them. When I do find more time I can reconstruct the object root graph from it from my own process. It this cool or what? You can also peek into the Finalization Queue to check if you did accidentally forget to dispose a whole bunch of objects … /// <summary> /// .NET 4.0 or above only. Get all finalizable objects which are ready for finalization and have no other object roots anymore. /// </summary> static void NotYetFinalizedObjects() { using (var dumper = new MemoryDumper()) { object[] finalizable = dumper.GetObjectsReadyForFinalization(); Console.WriteLine("Currently {0} objects of types {1} are ready for finalization. Consider disposing them before.", finalizable.Length, String.Join(",", finalizable.ToLookup( x=> x.GetType() ) .Select( x=> x.Key.Name)) ); } } How does it work? The W of WMemoryProfiler is a good hint. It does employ Windbg and SOS dll to do the heavy lifting and concentrates on an easy to use Api which does hide completely Windbg. If you do not want to see Windbg you will never see it. In my experience the most complex thing is actually to download Windbg from the Windows 8 Stanalone SDK. This is described in the Readme and the exception you are greeted with if it is missing in much greater detail. So I will not go into this here.   What Next? Depending on the feedback I do get I can imagine some features which might be useful as well Calculate first order GC Roots from the actual object graph Identify global statics in Types in object graph Support read out of finalization queue of .NET 2.0 as well. Support Memory Dump analysis (again a feature only supported by commercial profilers in their professional editions if it is supported at all) Deserialize objects from a memory dump into a live process back (this would need some more investigation but it is doable) The last item needs some explanation. Why on earth would you want to do that? The basic idea is to store in your live process some logging/tracing data which can become quite big but since it is never written to it is very fast to generate. When your process crashes with a memory dump you could transfer this data structure back into a live viewer which can then nicely display your program state at the point it did crash. This is an advanced trouble shooting technique I have not seen anywhere yet but it could be quite useful. You can have here a look at the current feature list of WMemoryProfiler with some examples.   How To Get Started? First I would download the released source package (it is tiny). And compile the complete project. Then you can compile the Example project (it has this name) and uncomment in the main method the scenario you want to check out. If you are greeted with an exception it is time to install the Windows 8 Standalone SDK which is described in great detail in the exception text. Thats it for the first round. I have seen something more limited in the Java world some years ago (now I cannot find the link anymore) but anyway. Now we have something much better.

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• How can I make KDE faster in Ubuntu 12.04. It's very slow

  - by Rizwan Rifan

  I installed the kubuntu-desktop package in Ubuntu 12.04 LTS, but the problem is KDE responses very slowly. If I click on an application's icon to run it, it appears after 10 seconds and sometimes does not appear at all. It hangs all the time. The cursor is almost impossible to follow because of the lag. I have read on the Internet that Unity uses more memory and CPU than KDE. But on my PC Unity runs smoothly and KDE does not. So what should I do to make KDE as fast, responsive and smooth as Unity? My specifications are as follows: RAM: 1.5 GB (DDR2) Processor: 3 GHz Dual Core Graphics Card: Intel HD graphics with 256 MB memory.

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• Desktop dims when Thunderbird and Firefox are launched

  - by deshmukh

  I am running Ubuntu 12.04 (almost default install regularly updated) Unity interface on ASUS X53U (AMD Brazos Dual Core C60 with 2GB RAM). On launching Thunderbird and Firefox, the application dims and the cursor changes to wait mode. In case of Thunderbird, this is most pronounced with the wait time of up to a minute. Memory status checked with free indicates around 500MB of free memory on such occasions. The OS is stable and I can switch to a different work-space, etc. What could this be? Is this something normal?

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• Move Data into the Grid for Scalable, Predictable Response Times

  - by JuergenKress

  CloudTran is pleased to introduce the availability of the CloudTran Transaction and Persistence Manager for creating scalable, reliable data services on the Oracle Coherence In-Memory Data Grid (IMDG). Use of IMDG architectures has been key to handling today’s web-scale loads because it eliminates database latency by storing important and frequently access data in memory instead of on disk. The CloudTran product lets developers easily use an IMDG for full ACID-compliant transactions without having to be concerned about the location or spread of data. The system has its own implementation of fast, scalable distributed transactions that does NOT depend on XA protocols but still guarantees all ACID properties. Plus, CloudTran asynchronously replicates data going into the IMDG to back-end datastores and back-up data centers, again ensuring ACID properties. CloudTran can be accessed through Java Persistence API (JPA via TopLink Grid) and now, through a new Low-Level API, or LLAPI. This is ideal for use in SOA applications that need data reliability, high availability, performance, and scalability. Still in limited beta release, the LLAPI gives developers the ability to use standard put/remove logic available in Coherence and then wrap logic with simple Spring annotations or XML+AspectJ to start transactions. An important feature of LLAPI is the ability to join transactions. This is a common outcome for SOA applications that need to reduce network traffic by aggregating data into single cache entries and then doing SOA service processing in the node holding the data. This results in the need to orchestrate transaction processing across multiple service calls. CloudTran has the capability to handle these “multi-client” transactions at speed with no loss in ACID properties. Developing software around an IMDG like Oracle Coherence is an important choice for today’s web-scale applications and services. But this introduces new architectural considerations to maintain scalability in light of increased network loads and data movement. Without using CloudTran, developers are faced with an incredibly difficult task to ensure data reliability, availability, performance, and scalability when working with an IMDG. Working with highly distributed data that is entirely volatile while stored in memory presents numerous edge cases where failures can result in data loss. The CloudTran product takes care of all of this, leaving developers with the confidence and peace of mind that all data is processed correctly. For those interested in evaluating the CloudTran product and IMDGs, take a look at this link for more information: http://www.CloudTran.com/downloadAPI.php, or, send your questions to [email protected]. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. BlogTwitterLinkedInMixForumWiki Technorati Tags: Coherence,cloudtran,cache,WebLogic Community,Oracle,OPN,Jürgen Kress

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• StreamInsight 2.1, meet LINQ

  - by Roman Schindlauer

  Someone recently called LINQ “magic” in my hearing. I leapt to LINQ’s defense immediately. Turns out some people don’t realize “magic” is can be a pejorative term. I thought LINQ needed demystification. Here’s your best demystification resource: http://blogs.msdn.com/b/mattwar/archive/2008/11/18/linq-links.aspx. I won’t repeat much of what Matt Warren says in his excellent series, but will talk about some core ideas and how they affect the 2.1 release of StreamInsight. Let’s tell the story of a LINQ query. Compile time It begins with some code: IQueryable<Product> products = ...; var query = from p in products             where p.Name == "Widget"             select p.ProductID; foreach (int id in query) {     ... When the code is compiled, the C# compiler (among other things) de-sugars the query expression (see C# spec section 7.16): ... var query = products.Where(p => p.Name == "Widget").Select(p => p.ProductID); ... Overload resolution subsequently binds the Queryable.Where<Product> and Queryable.Select<Product, int> extension methods (see C# spec sections 7.5 and 7.6.5). After overload resolution, the compiler knows something interesting about the anonymous functions (lambda syntax) in the de-sugared code: they must be converted to expression trees, i.e.,“an object structure that represents the structure of the anonymous function itself” (see C# spec section 6.5). The conversion is equivalent to the following rewrite: ... var prm1 = Expression.Parameter(typeof(Product), "p"); var prm2 = Expression.Parameter(typeof(Product), "p"); var query = Queryable.Select<Product, int>(     Queryable.Where<Product>(         products,         Expression.Lambda<Func<Product, bool>>(Expression.Property(prm1, "Name"), prm1)),         Expression.Lambda<Func<Product, int>>(Expression.Property(prm2, "ProductID"), prm2)); ... If the “products” expression had type IEnumerable<Product>, the compiler would have chosen the Enumerable.Where and Enumerable.Select extension methods instead, in which case the anonymous functions would have been converted to delegates. At this point, we’ve reduced the LINQ query to familiar code that will compile in C# 2.0. (Note that I’m using C# snippets to illustrate transformations that occur in the compiler, not to suggest a viable compiler design!) Runtime When the above program is executed, the Queryable.Where method is invoked. It takes two arguments. The first is an IQueryable<> instance that exposes an Expression property and a Provider property. The second is an expression tree. The Queryable.Where method implementation looks something like this: public static IQueryable<T> Where<T>(this IQueryable<T> source, Expression<Func<T, bool>> predicate) {     return source.Provider.CreateQuery<T>(     Expression.Call(this method, source.Expression, Expression.Quote(predicate))); } Notice that the method is really just composing a new expression tree that calls itself with arguments derived from the source and predicate arguments. Also notice that the query object returned from the method is associated with the same provider as the source query. By invoking operator methods, we’re constructing an expression tree that describes a query. Interestingly, the compiler and operator methods are colluding to construct a query expression tree. The important takeaway is that expression trees are built in one of two ways: (1) by the compiler when it sees an anonymous function that needs to be converted to an expression tree, and; (2) by a query operator method that constructs a new queryable object with an expression tree rooted in a call to the operator method (self-referential). Next we hit the foreach block. At this point, the power of LINQ queries becomes apparent. The provider is able to determine how the query expression tree is evaluated! The code that began our story was intentionally vague about the definition of the “products” collection. Maybe it is a queryable in-memory collection of products: var products = new[]     { new Product { Name = "Widget", ProductID = 1 } }.AsQueryable(); The in-memory LINQ provider works by rewriting Queryable method calls to Enumerable method calls in the query expression tree. It then compiles the expression tree and evaluates it. It should be mentioned that the provider does not blindly rewrite all Queryable calls. It only rewrites a call when its arguments have been rewritten in a way that introduces a type mismatch, e.g. the first argument to Queryable.Where<Product> being rewritten as an expression of type IEnumerable<Product> from IQueryable<Product>. The type mismatch is triggered initially by a “leaf” expression like the one associated with the AsQueryable query: when the provider recognizes one of its own leaf expressions, it replaces the expression with the original IEnumerable<> constant expression. I like to think of this rewrite process as “type irritation” because the rewritten leaf expression is like a foreign body that triggers an immune response (further rewrites) in the tree. The technique ensures that only those portions of the expression tree constructed by a particular provider are rewritten by that provider: no type irritation, no rewrite. Let’s consider the behavior of an alternative LINQ provider. If “products” is a collection created by a LINQ to SQL provider: var products = new NorthwindDataContext().Products; the provider rewrites the expression tree as a SQL query that is then evaluated by your favorite RDBMS. The predicate may ultimately be evaluated using an index! In this example, the expression associated with the Products property is the “leaf” expression. StreamInsight 2.1 For the in-memory LINQ to Objects provider, a leaf is an in-memory collection. For LINQ to SQL, a leaf is a table or view. When defining a “process” in StreamInsight 2.1, what is a leaf? To StreamInsight a leaf is logic: an adapter, a sequence, or even a query targeting an entirely different LINQ provider! How do we represent the logic? Remember that a standing query may outlive the client that provisioned it. A reference to a sequence object in the client application is therefore not terribly useful. But if we instead represent the code constructing the sequence as an expression, we can host the sequence in the server: using (var server = Server.Connect(...)) {     var app = server.Applications["my application"];     var source = app.DefineObservable(() => Observable.Range(0, 10, Scheduler.NewThread));     var query = from i in source where i % 2 == 0 select i; } Example 1: defining a source and composing a query Let’s look in more detail at what’s happening in example 1. We first connect to the remote server and retrieve an existing app. Next, we define a simple Reactive sequence using the Observable.Range method. Notice that the call to the Range method is in the body of an anonymous function. This is important because it means the source sequence definition is in the form of an expression, rather than simply an opaque reference to an IObservable<int> object. The variation in Example 2 fails. Although it looks similar, the sequence is now a reference to an in-memory observable collection: var local = Observable.Range(0, 10, Scheduler.NewThread); var source = app.DefineObservable(() => local); // can’t serialize ‘local’! Example 2: error referencing unserializable local object The Define* methods support definitions of operator tree leaves that target the StreamInsight server. These methods all have the same basic structure. The definition argument is a lambda expression taking between 0 and 16 arguments and returning a source or sink. The method returns a proxy for the source or sink that can then be used for the usual style of LINQ query composition. The “define” methods exploit the compile-time C# feature that converts anonymous functions into translatable expression trees! Query composition exploits the runtime pattern that allows expression trees to be constructed by operators taking queryable and expression (Expression<>) arguments. The practical upshot: once you’ve Defined a source, you can compose LINQ queries in the familiar way using query expressions and operator combinators. Notably, queries can be composed using pull-sequences (LINQ to Objects IQueryable<> inputs), push sequences (Reactive IQbservable<> inputs), and temporal sequences (StreamInsight IQStreamable<> inputs). You can even construct processes that span these three domains using “bridge” method overloads (ToEnumerable, ToObservable and To*Streamable). Finally, the targeted rewrite via type irritation pattern is used to ensure that StreamInsight computations can leverage other LINQ providers as well. Consider the following example (this example depends on Interactive Extensions): var source = app.DefineEnumerable((int id) =>     EnumerableEx.Using(() =>         new NorthwindDataContext(), context =>             from p in context.Products             where p.ProductID == id             select p.ProductName)); Within the definition, StreamInsight has no reason to suspect that it ‘owns’ the Queryable.Where and Queryable.Select calls, and it can therefore defer to LINQ to SQL! Let’s use this source in the context of a StreamInsight process: var sink = app.DefineObserver(() => Observer.Create<string>(Console.WriteLine)); var query = from name in source(1).ToObservable()             where name == "Widget"             select name; using (query.Bind(sink).Run("process")) {     ... } When we run the binding, the source portion which filters on product ID and projects the product name is evaluated by SQL Server. Outside of the definition, responsibility for evaluation shifts to the StreamInsight server where we create a bridge to the Reactive Framework (using ToObservable) and evaluate an additional predicate. It’s incredibly easy to define computations that span multiple domains using these new features in StreamInsight 2.1! Regards, The StreamInsight Team

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• SQL 2014 does data the way developers want

  - by Rob Farley

  A post I’ve been meaning to write for a while, good that it fits with this month’s T-SQL Tuesday, hosted by Joey D’Antoni (@jdanton) Ever since I got into databases, I’ve been a fan. I studied Pure Maths at university (as well as Computer Science), and am very comfortable with Set Theory, which undergirds relational database concepts. But I’ve also spent a long time as a developer, and appreciate that that databases don’t exactly fit within the stuff I learned in my first year of uni, particularly the “Algorithms and Data Structures” subject, in which we studied concepts like linked lists. Writing in languages like C, we used pointers to quickly move around data, without a database in sight. Of course, if we had a power failure all this data was lost, as it was only persisted in RAM. Perhaps it’s why I’m a fan of database internals, of indexes, latches, execution plans, and so on – the developer in me wants to be reassured that we’re getting to the data as efficiently as possible. Back when SQL Server 2005 was approaching, one of the big stories was around CLR. Many were saying that T-SQL stored procedures would be a thing of the past because we now had CLR, and that obviously going to be much faster than using the abstracted T-SQL. Around the same time, we were seeing technologies like Linq-to-SQL produce poor T-SQL equivalents, and developers had had a gutful. They wanted to move away from T-SQL, having lost trust in it. I was never one of those developers, because I’d looked under the covers and knew that despite being abstracted, T-SQL was still a good way of getting to data. It worked for me, appealing to both my Set Theory side and my Developer side. CLR hasn’t exactly become the default option for stored procedures, although there are plenty of situations where it can be useful for getting faster performance. SQL Server 2014 is different though, through Hekaton – its In-Memory OLTP environment. When you create a table using Hekaton (that is, a memory-optimized one), the table you create is the kind of thing you’d’ve made as a developer. It creates code in C leveraging structs and pointers and arrays, which it compiles into fast code. When you insert data into it, it creates a new instance of a struct in memory, and adds it to an array. When the insert is committed, a small write is made to the transaction to make sure it’s durable, but none of the locking and latching behaviour that typifies transactional systems is needed. Indexes are done using hashes and using bw-trees (which avoid locking through the use of pointers) and by handling each updates as a delete-and-insert. This is data the way that developers do it when they’re coding for performance – the way I was taught at university before I learned about databases. Being done in C, it compiles to very quick code, and although these tables don’t support every feature that regular SQL tables do, this is still an excellent direction that has been taken. @rob_farley

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• Why wifi doesn't work in this case?

  - by xRobot

  I have a brand new notebook where I have installed Windows 7 and Ubuntu 12.04 LTS 64bit in dual boot. In windows 7 wifi works but in Ubuntu not. Could you help me please ? iwconfig lo no wireless extensions. wlan0 IEEE 802.11bgn ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=20 dBm Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off eth0 no wireless extensions. lshw -C network *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:01:00.0 logical name: eth0 version: 07 serial: b4:b5:1f:1b:9a:56 size: 10Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half firmware=rtl8168e-3_0.0.4 03/27/12 latency=0 link=no multicast=yes port=MII speed=10Mbit/s resources: irq:41 ioport:3000(size=256) memory:c2404000-c2404fff memory:c2400000-c2403fff *-network description: Wireless interface product: Ralink corp. vendor: Ralink corp. physical id: 0 bus info: pci@0000:02:00.0 logical name: wlan0 version: 00 serial: 84:4b:f4:0a:3a:22 width: 32 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=rt2800pci driverversion=3.2.0-31-generic firmware=0.34 latency=0 link=no multicast=yes wireless=IEEE 802.11bgn resources: irq:18 memory:c2500000-c250ffff lspci | grep -i net 01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 07) 02:00.0 Network controller: Ralink corp. Device 539a iwlist scan lo Interface doesn't support scanning. wlan0 Interface doesn't support scanning : Device or resource busy eth0 Interface doesn't support scanning. lsmod Module Size Used by rfcomm 47604 0 bnep 18281 2 bluetooth 180104 10 rfcomm,bnep parport_pc 32866 0 ppdev 17113 0 snd_hda_codec_hdmi 32474 1 snd_hda_codec_realtek 224173 1 joydev 17693 0 hp_wmi 18092 0 sparse_keymap 13890 1 hp_wmi snd_hda_intel 33773 3 snd_hda_codec 127706 3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel snd_hwdep 13668 1 snd_hda_codec snd_pcm 97188 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec snd_seq_midi 13324 0 snd_rawmidi 30748 1 snd_seq_midi snd_seq_midi_event 14899 1 snd_seq_midi snd_seq 61896 2 snd_seq_midi,snd_seq_midi_event snd_timer 29990 2 snd_pcm,snd_seq snd_seq_device 14540 3 snd_seq_midi,snd_rawmidi,snd_seq psmouse 97362 0 snd 78855 16 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device arc4 12529 2 rt2800pci 18715 0 rt2800lib 58925 1 rt2800pci crc_ccitt 12667 1 rt2800lib rt2x00pci 14577 1 rt2800pci rt2x00lib 51144 3 rt2800pci,rt2800lib,rt2x00pci mac80211 506816 3 rt2800lib,rt2x00pci,rt2x00lib soundcore 15091 1 snd mac_hid 13253 0 uvcvideo 72627 0 videodev 98259 1 uvcvideo v4l2_compat_ioctl32 17128 1 videodev wmi 19256 1 hp_wmi i915 473240 3 cfg80211 205544 2 rt2x00lib,mac80211 eeprom_93cx6 12725 1 rt2800pci drm_kms_helper 46978 1 i915 drm 242038 4 i915,drm_kms_helper i2c_algo_bit 13423 1 i915 snd_page_alloc 18529 2 snd_hda_intel,snd_pcm mei 41616 0 serio_raw 13211 0 video 19596 1 i915 lp 17799 0 parport 46562 3 parport_pc,ppdev,lp usbhid 47199 0 hid 99559 1 usbhid r8169 62099 0 rfkill list: # rfkill list 0: phy0: Wireless LAN Soft blocked: no Hard blocked: no 1: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: no

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• returning a heap block by reference in c++

  - by basicR

  I was trying to brush up my c++ skills. I got 2 functions: concat_HeapVal() returns the output heap variable by value concat_HeapRef() returns the output heap variable by reference When main() runs it will be on stack,s1 and s2 will be on stack, I pass the value by ref only and in each of the below functions, I create a variable on heap and concat them. When concat_HeapVal() is called it returns me the correct output. When concat_HeapRef() is called it returns me some memory address (wrong output). Why? I use new operator in both the functions. Hence it allocates on heap. So when I return by reference, heap will still be VALID even when my main() stack memory goes out of scope. So it's left to OS to cleanup the memory. Right? string& concat_HeapRef(const string& s1, const string& s2) { string *temp = new string(); temp->append(s1); temp->append(s2); return *temp; } string* concat_HeapVal(const string& s1, const string& s2) { string *temp = new string(); temp->append(s1); temp->append(s2); return temp; } int main() { string s1,s2; string heapOPRef; string *heapOPVal; cout<<"String Conact Experimentations\n"; cout<<"Enter s-1 : "; cin>>s1; cout<<"Enter s-2 : "; cin>>s2; heapOPRef = concat_HeapRef(s1,s2); heapOPVal = concat_HeapVal(s1,s2); cout<<heapOPRef<<" "<<heapOPVal<<" "<<endl; return -9; }

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• How should I organize my matrices in a 3D game engine?

  - by Need4Sleep

  I'm working with a group of people from around the world to create a game engine (and hopefully a game with it) within the next upcoming years. My first task is to write a camera class for the engine to use in order to add cameras to the scene, with position and follow points. The problem I have is with using matrices for transformations in the class, should I keep matrices separate to each class? Such as have the model matrix in the model class, camera matrix in the camera class, or have all matrices placed in one class/chuck? I could see pros and cons for each method, but I wanted to hear some input form a more professional standpoint.

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• Advanced Analytics Oracle Data Mining - NEW 2-Day Training Course

  - by Mike.Hallett(at)Oracle-BI&EPM

  A NEW 2-Day Oracle University (OU) Instructor Led Course on Oracle Data Mining has been developed for partners and customers to learn more about data mining, predictive analytics and knowledge discovery inside the Oracle Database. Oracle Data Mining, provides data mining algorithms that run native for high performance in-database model building and model deployment. This OU course is a great way to learn the advantages and benefits of "big data analytics"; mining data, building and deploying "predictive analytics" all inside the Oracle Database and to work with OBI. To register for a class, click here, then click on View Schedule to see the latest scheduled classes and/or submit your information expressing interest in attending a class.

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• How to understand Linux kernel source code for a beginner?

  - by user16867

  I am a student interested in working on Memory Management, particularly the page replacement component of the linux kernel. What are the different guides that can help me to begin understanding the kernel source? I have tried to read the book Understanding the Linux Virutal Memory Manager by Mel Gorman and Understanding the Linux Kernel by Cesati and Bovet, but they do not explain the flow of control through the code. They only end up explaining various data structures used and the work various functions perform. This makes the code more confusing. My project deals with tweaking the page replacement algorithm in a mainstream kernel and analyse its performance for a set of workloads. Is there a flavor of the linux kernel that would be easier to understand(if not the linux-2.6.xx kernel)?

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• What are these errors when I try to "make" the driver of my wireless network?

  - by Tom Brito

  I got got a wireless to usb adapter, and I'm having some trouble to install the drivers on Ubuntu. First of all, the readme file say to use the "make" command, and I already got errors: $ make make[1]: Entering directory `/usr/src/linux-headers-2.6.35-22-generic' CC [M] /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.o /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c: In function ‘rtl8192_usb_probe’: /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12325: error: ‘struct net_device’ has no member named ‘open’ /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12326: error: ‘struct net_device’ has no member named ‘stop’ /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12327: error: ‘struct net_device’ has no member named ‘tx_timeout’ /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12328: error: ‘struct net_device’ has no member named ‘do_ioctl’ /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12329: error: ‘struct net_device’ has no member named ‘set_multicast_list’ /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12330: error: ‘struct net_device’ has no member named ‘set_mac_address’ /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12331: error: ‘struct net_device’ has no member named ‘get_stats’ /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.c:12332: error: ‘struct net_device’ has no member named ‘hard_start_xmit’ make[2]: *** [/home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u/r8192U_core.o] Error 1 make[1]: *** [_module_/home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/HAL/rtl8192u] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-2.6.35-22-generic' make: *** [all] Error 2 /home/wellington/Desktop/rtl8192su_linux_2.4_2.6.0003.0301.2010/ is the path where I copied the drivers on my computer. Any idea how to solve this? (I don't even know what the error is...) update: sudo lshw -class network *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:01:00.0 logical name: eth0 version: 03 serial: 78:e3:b5:e7:5f:6e size: 10MB/s capacity: 1GB/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half latency=0 link=no multicast=yes port=MII speed=10MB/s resources: irq:42 ioport:d800(size=256) memory:fbeff000-fbefffff memory:faffc000-faffffff memory:fbec0000-fbedffff *-network DISABLED description: Wireless interface physical id: 2 logical name: wlan0 serial: 00:26:18:a1:ae:64 capabilities: ethernet physical wireless configuration: broadcast=yes multicast=yes wireless=802.11b/g

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• Multiple vulnerabilities in Wireshark

  - by RitwikGhoshal

  CVE DescriptionCVSSv2 Base ScoreComponentProduct and Resolution CVE-2012-4285 Numeric Errors vulnerability 3.3 Wireshark Solaris 11 11/11 SRU 13.4 CVE-2012-4286 Numeric Errors vulnerability 4.3 CVE-2012-4287 Resource Management Errors vulnerability 5.0 CVE-2012-4288 Numeric Errors vulnerability 3.3 CVE-2012-4289 Resource Management Errors vulnerability 3.3 CVE-2012-4290 Resource Management Errors vulnerability 3.3 CVE-2012-4291 Resource Management Errors vulnerability 3.3 CVE-2012-4292 Improper Input Validation vulnerability 3.3 CVE-2012-4293 Numeric Errors vulnerability 3.3 CVE-2012-4294 Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability 5.8 CVE-2012-4295 Denial of Service (DoS) vulnerability 3.3 CVE-2012-4296 Resource Management Errors vulnerability 3.3 CVE-2012-4297 Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability 8.3 CVE-2012-4298 Numeric Errors vulnerability 5.4 This notification describes vulnerabilities fixed in third-party components that are included in Oracle's product distributions.Information about vulnerabilities affecting Oracle products can be found on Oracle Critical Patch Updates and Security Alerts page.

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• Getting front audio jacks to work

  - by Ashfame

  I run Ubuntu 10.10 on my Intel D945. My front audio ports don't work in Ubuntu, the rear one does. I never got it working earlier when I had Ubuntu 10.04 but this time I am going to try it again. My codec is SigmaTel STAC9227 My ALSA information is here. Handy details: !!ALSA Version !!------------ Driver version: 1.0.23 Library version: 1.0.23 Utilities version: 1.0.23 !!Loaded ALSA modules !!------------------- snd_hda_intel snd_hda_intel I know something that I will have to change the model of my module to make the front audio jack works but I couldn't find a model related line in my ALSA configuration file - /etc/modprobe.d/alsa-base.conf (I was able to get to that point in Ubuntu 10.04, may be something has changed). How can I proceed from here?

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• When to use an Array vs When to use a Vector, when dealing with GameObjects?

  - by user32465

  I understand that from other answers, Arrays and Vectors are the best choices. Many on SE claim that Linked Lists and Maps are bad for video game programming. I understand that for the most part, I can use Arrays. However, I don't really understand exactly when to use Vectors over Arrays. Why even use Vectors? Wouldn't it be best if I simply always used an Array, that way I know how much memory my game needs? Specifically my game would only ever load a single "Map" area of tiles, such as Map[100][100], so I could very easily have an array of GameObjectContainer GameObjects[100][100], which would reserve an entire map's worth of possible gameobjects, correct? So why use a Vector instead? Memory is quite large on modern hardware.

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• Exalytics OBI11g Partner Training 3-day hands-on Workshops

  - by Mike.Hallett(at)Oracle-BI&EPM

  These FREE to OPN Partners hands-on workshops highlight both the hardware and software components that are engineered to work together to deliver Oracle Exalytics - an optimized version of the industry-leading Oracle TimesTen In-Memory Database with analytic extensions, a highly scalable Oracle server designed specifically for in-memory business intelligence, and Oracle's proven Business Intelligence Foundation (OBI 11g v 11.1.1.6 and Essbase) with enhanced visualization capabilities and performance optimizations. Priority will be given to Partner individuals who have passed or scheduled to take the Oracle Business Intelligence Foundation Suite 11g Essentials (1Z1-591) exam, and to Partners who have purchased an Exalytics for their own data centres to demonstrate it to their clients. Topics covered will include: Exalytics Architectural Overview Upgrade and Lifecycle Management Times Ten for Exalytics Summary Advisor Utility Essbase and EPM System on Exalytics Dashboard and Analysis Interactions OBIEE 11.1.1.6 Features and Advanced Topics After taking this course, you will be well prepared to architect, build, demo, and implement an end-to-end Exalytics solution.You will also be able to extend your current analytical and enterprise performance management application implementations with numerous Oracle technologies specifically enhanced to take advantage of the compute capacity and in-memory capabilities of Oracle Exalytics. Prerequisites Experience and understanding of OBIEE 11g is required ·       Previous attendance of Oracle Business Intelligence Foundation Suite Workshop or BIEE 11g Introduction Workshop is highly recommended, and priority will be given to Partner individuals who have passed or scheduled to take the Oracle Business Intelligence Foundation Suite 11g Essentials (1Z1-591) exam. Good understanding of data warehousing and data modelling for reporting and analysis purpose.  Strong experience with database technologies preferred Attendee to provide their own laptops which must meet the following minimum hardware/software requirements: Hardware Minimum 8GB RAM 60 GB free disk space (includes staging) USB 2.0 port (at least one available) It is strongly recommended that you bring a mouse. You will be working in a development environment and using the mouse heavily. Software One of the following operating systems: 64-bit Windows host/laptop OS 64-bit host/laptop OS with a Windows VM (XP, Server, or Win 7, BIC2g, etc.) Internet Explorer 7.x/8.x or Firefox 3.5.x WINRAR or 7ziputility to unzip workshop files: Download-able from http://www.win-rar.com/download.html Download-able from http://www.7zip.com/ Oracle VirtualBox 4.0.2 or higher Downloadable from http://www.virtualbox.org/wiki/Downloads CPU virtualization mode needs to be enabled. We will provide guidance on the day of the workshop.  Attendees will be given a VirtualBox image containing a pre-installed Oracle Exalytics environment. Register Here for 3-day Workshops: 11-Dec-12 Birmingham UK 29-Jan-13 Utrecht NL 12-Feb-13 Frankfurt Germany 12-Mar-13 Moscow Russia

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• Class Versus Struct

  - by Prometheus87

  In C++ and other influenced languages there is a construct called Structure (struct) and we all know the class. Both are capable of holding functions and variables. some differences are 1. Class is given memory in heap and struct is given memory in stack 2. in class variable are private by default and in struct thy are public My question is that struct was somehow abandoned for Class. Why? other that abstraction, a struct can do all the same stuff a class does. Then why abandon it?

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• Avoiding coupling

  - by Seralize

  It is also true that a system may become so coupled, where each class is dependent on other classes that depend on other classes, that it is no longer possible to make a change in one place without having a ripple effect and having to make subsequent changes in many places.[1] This is why using an interface or an abstract class can be valuable in any object-oriented software project. Quote from Wikipedia Starting from scratch I'm starting from scratch with a project that I recently finished because I found the code to be too tightly coupled and hard to refactor, even when using MVC. I will be using MVC on my new project aswell but want to try and avoid the pitfalls this time, hopefully with your help. Project summary My issue is that I really wish to keep the Controller as clean as possible, but it seems like I can't do this. The basic idea of the program is that the user picks wordlists which is sent to the game engine. It will pick random words from the lists until there are none left. Problem at hand My main problem is that the game will have 'modes', and need to check the input in different ways through a method called checkWord(), but exactly where to put this and how to abstract it properly is a challenge to me. I'm new to design patterns, so not sure whether there exist any might fit my problem. My own attempt at abstraction Here is what I've gotten so far after hours of 'refactoring' the design plans, and I know it's long, but it's the best I could do to try and give you an overview (Note: As this is the sketch, anything is subject to change, all help and advice is very welcome. Also note the marked coupling points): Wordlist class Wordlist { // Basic CRUD etc. here! // Other sample methods: public function wordlistCount($user_id) {} // Returns count of how many wordlists a user has public function getAll($user_id) {} // Returns all wordlists of a user } Word class Word { // Basic CRUD etc. here! // Other sample methods: public function wordCount($wordlist_id) {} // Returns count of words in a wordlist public function getAll($wordlist_id) {} // Returns all words from a wordlist public function getWordInfo($word_id) {} // Returns information about a word } Wordpicker class Wordpicker { // The class needs to know which words and wordlists to exclude protected $_used_words = array(); protected $_used_wordlists = array(); // Wordlists to pick words from protected $_wordlists = array(); /* Public Methods */ public function setWordlists($wordlists = array()) {} public function setUsedWords($used_words = array()) {} public function setUsedWordlists($used_wordlists = array()) {} public function getRandomWord() {} // COUPLING POINT! Will most likely need to communicate with both the Wordlist and Word classes /* Protected Methods */ protected function _checkAvailableWordlists() {} // COUPLING POINT! Might need to check if wordlists are deleted etc. protected function _checkAvailableWords() {} // COUPLING POINT! Method needs to get all words in a wordlist from the Word class } Game class Game { protected $_session_id; // The ID of a game session which gets stored in the database along with game details protected $_game_info = array(); // Game instantiation public function __construct($user_id) { if (! $this->_session_id = $this->_gameExists($user_id)) { // New game } else { // Resume game } } // This is the method I tried to make flexible by using abstract classes etc. // Does it even belong in this class at all? public function checkWord($answer, $native_word, $translation) {} // This method checks the answer against the native word / translation word, depending on game mode public function getGameInfo() {} // Returns information about a game session, or creates it if it does not exist public function deleteSession($session_id) {} // Deletes a game session from the database // Methods dealing with game session information protected function _gameExists($user_id) {} protected function _getProgress($session_id) {} protected function _updateProgress($game_info = array()) {} } The Game /* CONTROLLER */ /* "Guess the word" page */ // User input $game_type = $_POST['game_type']; // Chosen with radio buttons etc. $wordlists = $_POST['wordlists']; // Chosen with checkboxes etc. // Starts a new game or resumes one from the database $game = new Game($_SESSION['user_id']); $game_info = $game->getGameInfo(); // Instantiates a new Wordpicker $wordpicker = new Wordpicker(); $wordpicker->setWordlists((isset($game_info['wordlists'])) ? $game_info['wordlists'] : $wordlists); $wordpicker->setUsedWordlists((isset($game_info['used_wordlists'])) ? $game_info['used_wordlists'] : NULL); $wordpicker->setUsedWords((isset($game_info['used_words'])) ? $game_info['used_words'] : NULL); // Fetches an available word if (! $word_id = $wordpicker->getRandomWord()) { // No more words left - game over! $game->deleteSession($game_info['id']); redirect(); } else { // Presents word details to the user $word = new Word(); $word_info = $word->getWordInfo($word_id); } The Bit to Finish /* CONTROLLER */ /* "Check the answer" page */ // ?????????????????? ( http://pastebin.com/cc6MtLTR ) Make sure you toggle the 'Layout Width' to the right for a better view. Thanks in advance. Questions To which extent should objects be loosely coupled? If object A needs info from object B, how is it supposed to get this without losing too much cohesion? As suggested in the comments, models should hold all business logic. However, as objects should be independent, where to glue them together? Should the model contain some sort of "index" or "client" area which connects the dots? Edit: So basically what I should do for a start is to make a new model which I can more easily call with oneliners such as $model->doAction(); // Lots of code in here which uses classes! How about the method for checking words? Should it be it's own object? I'm not sure where I should put it as it's pretty much part of the 'game'. But on another hand, I could just leave out the 'abstraction and OOPness' and make it a method of the 'client model' which will be encapsulated from the controller anyway. Very unsure about this.

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• Does anyone know of any work being done on EEE transformer?

  - by Matthew

  I recently got a (few) nexus 7's to install and enjoy ubuntu on. Which is great and all, but from what I've read online and the issues I have experienced myself the Nexus 7 has way to many serious defects. Such as: Audio jack not working Screen lifting Screen ghosting out (The very first one) Instant drop in battery life (happened to one of mine) Internal memory malfunctions (The latest issue I've had, the internal memory went completely bad) If you need to read other horror stories you can simply check out XDA developers forum, lots of people are having issues. I'd really like to enjoy ubuntu on a different device, I think the Transformer prime would make way more sense (usability and stability wise). Have there been any hacks/mods to get it running on this device?

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• What is a right datatype in C++ for OpenGL scene representation with use of GLSL

  - by Rarach

  I am programming in C++ OpenGl with GLSL. Until now I have been using a data structure that is composed of std::vector filled with structures of vertexes and with their parameters (position , normal, color ...) as a global variable for all the code. My question is, as I am using VBOs for drawing - is this a good approach to this problem? I am asking because I happen to have a lot of memory related trouble with this structure. I am trying to generate a terrain with a lot of vertices - more than 1 million. This seems to work, but as I refill the buffer I get memory related issues (crushes that occur, more or less randomly). So again the question is, is this a good data structure to use / and look for the faults in my code, or should I change to something else? Or what data structure would be advisable?

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• What's the difference or purpose of a file format like ELF when flat binaries take up less space and can do the same thing?

  - by Sinister Clock

  I will give a better description now. In Linux driver development you need to follow a specification using an ELF file format as a finalized executable, i.e., that right there is not flat, it has headers, entry fields, and is basically carrying more weight than just a flat binary with opcodes. What is the purpose or in-depth difference of a Linux ELF file for a driver to interact with the video hardware, and, say, a bare, flat x86 16-bit binary I write that makes use of emulated graphics mode on a graphics card and writes to memory(besides the fact that the Linux driver probably is specific to making full use of the hardware and not just the emulated, backwards compatible memory accessing scheme). To sum it up, what is a difference or purpose of a binary like ELF with different headers and settings and just a flat binary with the necessary opcodes/instructions/data to do the same thing, just without any specific format? Example: Windows uses PE, Mac uses Mach-O/PEF, Linux uses ELF/FATELF, Unix uses COFF. What do any of them really mean or designate if you can just go flat, especially with a device driver which is system software.

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• Red Hat Extends Linux Subscriptions to Cloud Computing

  Red Hat Cloud Access extends Linux subscription model for cloud computing deployments on Amazon EC2.

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