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• In Java, is there a performance gain in using interfaces for complex models?

  - by Gnoupi

  The title is hardly understandable, but I'm not sure how to summarize that another way. Any edit to clarify is welcome. I have been told, and recommended to use interfaces to improve performances, even in a case which doesn't especially call for the regular "interface" role. In this case, the objects are big models (in a MVC meaning), with many methods and fields. The "good use" that has been recommended to me is to create an interface, with its unique implementation. There won't be any other class implementing this interface, for sure. I have been told that this is better to do so, because it "exposes less" (or something close) to the other classes which will use methods from this class, as these objects are referring to the object from its interface (all public methods from the implementation being reproduced in the interface). This seems quite strange to me, as it seems like a C++ use to me (with header files). There I see the point, but in Java? Is there really a point in making an interface for such unique implementation? I would really appreciate some clarifications on the topic, so I could justify not following such kind of behavior, and the hassle it creates from duplicating all declarations. Edit: Plenty of valid points in most answers, I'm wondering if I won't switch this question for a community wiki, so we can regroup these points in more structured answers.

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• Java Inheritance doubt in parameterised collection

  - by Gala101

  It's obvious that a parent class's object can hold a reference to a child, but does this not hold true in case of parameterised collection ?? eg: Car class is parent of Sedan So public void doSomething(Car c){ ... } public void caller(){ Sedan s = new Sedan(); doSomething(s); } is obviously valid But public void doSomething(Collection<Car> c){ ... } public void caller(){ Collection<Sedan> s = new ArrayList<Sedan>(); doSomething(s); } Fails to compile Can someone please point out why? and also, how to implement such a scenario where a function needs to iterate through a Collection of parent objects, modifying only the fields present in parent class, using parent class methods, but the calling methods (say 3 different methods) pass the collection of three different subtypes.. Ofcourse it compiles fine if I do as below: public void doSomething(Collection<Car> c){ ... } public void caller(){ Collection s = new ArrayList<Sedan>(); doSomething(s); }

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• C#: at design time, how can I reliably determine the type of a variable that is declared using var?

  - by Cheeso

  I'm working on a completion (intellisense) facility for C# in emacs. The idea is, if a user types a fragment, then asks for completion via a particular keystroke combination, the completion facility will use .NET reflection to determine the possible completions. Doing this requires that the type of the thing being completed, be known. If it's a string, it has a set of known methods; if it's an Int32, it has a separate set of methods, and so on. Using semantic, a code lexer/parser package available in emacs, I can locate the variable declarations, and their types. Given that, it's straightforward to use reflection to get the methods and properties on the type, and then present the list of options to the user. The problem arrives when the code uses var in the declaration. How can I reliably determine the actual type used, when the variable is declared with the var keyword? Just to be clear, I don't need to determine it at runtime. I want to determine it at "Design time". So far the best idea I have is: extract the declaration statement, eg var foo = "a string value"; concatenate a statement foo.GetType(); dynamically compile the resulting C# fragment it into a new assembly load the assembly into a new AppDomain, run the framgment and get the return type. unload and discard the assembly This sounds awfully heavyweight, for each completion request in the editor. Any better ideas out there?

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• Hibernate Session flush behaviour [ and Spring @Transactional ]

  - by EugeneP

  I use Spring and Hibernate in a web-app, SessionFactory is injected into a DAO bean, and then this DAO is used in a Servlet through webservicecontext. DAO methods are transactional, inside one of the methods I use ... getCurrentSession().save(myObject); One servlet calls this method with an object passed. The update seems to not be flushed at once, it takes about 5 seconds to see the changes in the database. The servlet's method in which that DAO's update method is called, takes a fraction of second to complete. After the @Transactional method of DAO is completed, flushing may NOT happen ? It does not seem to be a rule [ I already see it ]. Then the question is this: what to do to force the session to flush after every DAO method? It may not be a good thing to do, but talking about a Service layer, some methods must end with immediate flush, and Hibernate Session behavior is not predictable. So what to do to guarantee that my @Transactional method persists all the changes after the last line of that method code? getCurrentSession().flush() is the only solution? p.s. I read somewhere that @Transactional IS ASSOCIATED with a DB Transaction. Method returns, transaction must be committed. I do not see this happens.

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• How to Implement an Interface that Requires Duplicate Member Names in C#?

  - by Will Marcouiller

  I often have to implement some interfaces such as IEnumerable<T> in my code. Each time, when implementing automatically, I encounter the following: public IEnumerator<T> GetEnumerator() { // Code here... } public IEnumerator GetEnumerator1() { // Code here... } Though I have to implement both GetEnumerator() methods, they impossibly can have the same name, even if we understand that they do the same, somehow. The compiler can't treat them as one being the overload of the other, because only the return type differs. When doing so, I manage to set the GetEnumerator1() accessor to private. This way, the compiler doesn't complaint about not implementing the interface member, and I simply throw a NotImplementedException within the methods body. However, I wonder whether it is a good practice, or if I shall proceed differently, as perhaps a method alias or something like so. What is the best approach while implementing an interface such as IEnumerable<T> that requires the implementation of two different methods with the same name?

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• Should I put actors in the Domain-Model/Class-Diagram?

  - by devoured elysium

  When designing both the domain-model and class-diagrams I am having some trouble understanding what to put in them. I'll give an example of what I mean: I am doing a vacations scheduler program, that has an Administrator and End-Users. The Administrator does a couple of things like registering End-Users in the program, changing their previleges, etc. The End-User can choose his vacations days, etc. I initially defined an Administrator and End-User as concepts in the domain-model, and later as classes in the class-diagram. In the class-diagram, both classes ended up having a couple of methods like Administrator.RegisterNewUser(); Administrator.UnregisterUser(int id); etc. Only after some time I realised that actually both Administrator and End-User are actors, and maybe I got this design totally wrong. Instead of filling Administrator and End-User classes with methods to do what my Use-Cases request, I could define other classes from the domain to do them, and have controllers handle the Use-Cases(actually, I decided to do one for each Use-Case). I could have a UserDatabase.RegisterNewUser() and UserDatabase.UnregisterUser(int id);, for example, instead of having those methods on the Administrator class. The idea would be to try to think of the whole vacation-scheduler as a "closed-program" that has a set of features and doesn't bother with things such as authentication, that should be internal/protected, being that the only public things I'd let the outside world see would be its controllers. Is this the right approach? Or am I getting this totally wrong? Is it generally bad idea to put Actors in the domain-model/class-diagrams? What are good rules of thumb for this? My lecturer is following Applying UML and Patterns, which I find awful, so I'd like to know where I could look up more info on this described actor-models situation. I'm still a bit confused about all of this, as this new approach is radically different from anything I've done before.

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• Trouble accessing fields of a serialized object in Java

  - by typoknig

  I have instantized a class that implements Serializable and I am trying to stream that object like this: try{ Socket socket = new Socket("localhost", 8000); ObjectOutputStream toServer = new ObjectOutputStream(socket.getOutputStream()); toServer.writeObject(myObject); } catch (IOException ex) { System.err.println(ex); } All good so far right? Then I am trying to read the fields of that object like this: //This is an inner class class HandleClient implements Runnable{ private ObjectInputStream fromClient; private Socket socket; // This socket was established earlier try { fromClient = new ObjectInputStream(socket.getInputStream()); GetField inputObjectFields = fromClient.readFields(); double myFristVariable = inputObjectFields.get("myFirstVariable", 0); int mySecondVariable = inputObjectFields.get("mySecondVariable", 0); //do stuff } catch (IOException ex) { System.err.println(ex); } catch (ClassNotFoundException ex) { System.err.println(ex); } finally { try { fromClient.close(); } catch (Exception ex) { ex.printStackTrace(); } } } But I always get the error: java.io.NotActiveException: not in call to readObject This is my first time streaming objects instead of primitive data types, what am I doing wrong? BONUS When I do get this working correctly, is the ENTIRE CLASS passed with the serialized object (i.e. will I have access to the methods of the object's class)? My reading suggests that the entire class is passed with the object, but I have been unable to use the objects methods thus far. How exactly do I call on the object's methods? In addition to my code above I also experimented with the readObject method, but I was probably using it wrong too because I couldn't get it to work. Please enlighten me.

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• Python class structure ... prep() method?

  - by Adam Nelson

  We have a metaclass, a class, and a child class for an alert system: class AlertMeta(type): """ Metaclass for all alerts Reads attrs and organizes AlertMessageType data """ def __new__(cls, base, name, attrs): new_class = super(AlertMeta, cls).__new__(cls, base, name, attrs) # do stuff to new_class return new_class class BaseAlert(object): """ BaseAlert objects should be instantiated in order to create new AlertItems. Alert objects have classmethods for dequeue (to batch AlertItems) and register (for associated a user to an AlertType and AlertMessageType) If the __init__ function recieves 'dequeue=True' as a kwarg, then all other arguments will be ignored and the Alert will check for messages to send """ __metaclass__ = AlertMeta def __init__(self, **kwargs): dequeue = kwargs.pop('dequeue',None) if kwargs: raise ValueError('Unexpected keyword arguments: %s' % kwargs) if dequeue: self.dequeue() else: # Do Normal init stuff def dequeue(self): """ Pop batched AlertItems """ # Dequeue from a custom queue class CustomAlert(BaseAlert): def __init__(self,**kwargs): # prepare custom init data super(BaseAlert, self).__init__(**kwargs) We would like to be able to make child classes of BaseAlert (CustomAlert) that allow us to run dequeue and to be able to run their own __init__ code. We think there are three ways to do this: Add a prep() method that returns True in the BaseAlert and is called by __init__. Child classes could define their own prep() methods. Make dequeue() a class method - however, alot of what dequeue() does requires non-class methods - so we'd have to make those class methods as well. Create a new class for dealing with the queue. Would this class extend BaseAlert? Is there a standard way of handling this type of situation?

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• Whether to put method code in a VB.Net data storage class, or put it in a separate class?

  - by Alan K

  TLDR summary: (a) Should I include (lengthy) method code in classes which may spawn multiple objects at runtime, (b) does doing so cause memory usage bloat, (c) if so should I "outsource" the code to a class that is loaded only once and have the class methods call that, or alternatively (d) does the code get loaded only once with the object definition anyway and I'm worrying about nothing? ........ I don't know whether there's a good answer to this but if there is I haven't found it yet by searching in the usual places. In my VB.Net (2010 if it matters) WinForms project I have about a dozen or so class objects in an object model. Some of these are pretty simple and do little more than act as data storage repositories. The ones further up the object model, however, have an increasing number of methods. There can be a significant number of higher level objects in use though the exact number will be runtime dependent so I can't be more precise than that. As I was writing the method code for one of the top level ones I noticed that it was starting to get quite lengthy. Memory optimisation is something of a lost art given how much memory the average PC has these days but I don't want to make my application a resource hog. So my questions for anyone who knows .Net way better than I do (of which there will be many) are: Is the code loaded into memory with each instance of the class that's created? Alternatively is it loaded only once with the definition of the class, and all derived objects just refer to that definition? (I'm not really sure how that could be possible given that, for example, event handlers can be assigned dynamically, but no harm asking.) If the answer to the first one is yes, would it be more efficient to write the code in a "utility" object which is loaded only once and called from the real class' methods? Any thoughts appreciated.

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• C# properties: How are they instantiated?

  - by Pedery

  Hi! This might be a pretty straightforward question, but I'm trying to understand some of the internal workings of the compilation. Very simply put, imagine an arbitrary object being instantiated. This object is then allocated on the heap. The object has a property of type PointF (which is value type), with a get and a set method. Imagine the get and the set method containing a few calculations for doing their work. How and where (stack/heap) and when is this code instantiated? This is the background for this question: I'm writing get and set methods for an object and these methods need to be accessed very frequently. The get and set code in itself is rather massive so I feared that in a worst case scenario the methods would be instantiated as an object or a value type with all internal code for every access of the property. On the other hand the code is probably instantiated when the main object is created and the CPU is simply told to jmp to the property code start. Anyway, this is what I want to have clarified.

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• possible to make codeigniter work with another framework?

  - by ajsie

  the situation is this. my client (who also is a programmer) asks me to develop an address book (with mysql database) with a lot of functions. then he can interact with some class methods i provide for him. kinda like an API. the situation is that the address book application is getting bigger and bigger, and i feel like its way better to use CodeIgniter to code it with MVC. i wonder if i can use codeigniter, then in some way give him the access to controller methods. eg. in a controller there are some functions u can call with the web browser. public function create_contact($information) {..} public function delete_contact($id) {..} public function get_contact($id) {..} however, these are just callable from web browser. how can i let my client have access to these functions like an API? then in his own application he can use: $result = $address_book-create_contact($information); if($result) { echo "Success"; } $contact = $address_book-get_contact($id); is this possible? cause i just know how to access the controller methods with the webbrowser. and i guess its not an option for him to use header(location) to access them. all suggestions to make this possible are welcomed! thanks

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• Exposing a C++ API to C#

  - by Siyfion

  So what I have is a C++ API contained within a *.dll and I want to use a C# application to call methods within the API. So far I have created a C++ / CLR project that includes the native C++ API and managed to create a "bridge" class that looks a bit like the following: ManagedBridge.h namespace ManagedAPIWrapper { public ref class Bridge { public: int bridge_test(void); int bridge_test2(api_struct* temp); } } ManagedBridge.cpp int Bridge::bridge_test(void) { return test(); } int Bridge::bridge_test2(api_struct* temp) { return test2(temp); } I also have a C# application that has a reference to the C++/CLR "Bridge.dll" and then uses the methods contained within. I have a number of problems with this: I can't figure out how to call bridge_test2 within the C# program, as it has no knowledge of what a api_struct actually is. I know that I need to marshal the object somewhere, but do I do it in the C# program or the C++/CLR bridge? This seems like a very long-winded way of exposing all of the methods in the API, is there not an easier way that I'm missing out? (That doesn't use P/Invoke!)

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• Minimal framework in Scala for collections with inheriting return type

  - by Rex Kerr

  Suppose one wants to build a novel generic class, Novel[A]. This class will contain lots of useful methods--perhaps it is a type of collection--and therefore you want to subclass it. But you want the methods to return the type of the subclass, not the original type. In Scala 2.8, what is the minimal amount of work one has to do so that methods of that class will return the relevant subclass, not the original? For example, class Novel[A] /* What goes here? */ { /* Must you have stuff here? */ def reverse/* What goes here instead of :Novel[A]? */ = //... def revrev/*?*/ = reverse.reverse } class ShortStory[A] extends Novel[A] /* What goes here? */ { override def reverse: /*?*/ = //... } val ss = new ShortStory[String] val ss2 = ss.revrev // Type had better be ShortStory[String], not Novel[String] Does this minimal amount change if you want Novel to be covariant? (The 2.8 collections do this among other things, but they also play with return types in more fancy (and useful) ways--the question is how little framework one can get away with if one only wants this subtypes-always-return-subtypes feature.)

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• Action on each method's return value

  - by RobGlynn

  What I'd like to do is take some action using the value returned by every method in a class. So for instance, if I have a class Order which has a method public Customer GetCustomer() { Customer CustomerInstance = // get customer return CustomerInstance; } Let's say I want to log the creation of these - Log(CustomerInstance); My options (AFAIK) are: Call Log() in each of these methods before returning the object. I'm not a fan of this because it gets unwieldy if used on a lot of classes with a lot of methods. It also is not an intrinsic part of the method's purpose. Use composition or inheritance to layer the log callon the Order class similar to: public Customer GetCustomer() { Customer CustomerInstance = this.originalCustomer.GetCustomer(); Log(CustomerInstance); return CustomerInstance; } I don't think this buys me anything over #1. Create extension methods on each of the returned types: Customer CustomerInstance = Order.GetCustomer().Log(); which has just as many downsides. I'm looking to do this for every (or almost every) object returned, automatically if possible, without having to write double the amount of code. I feel like I'm either trying to bend the language into doing something it's not supposed to, or failing to recognize some language feature that would enable this. Possible solutions would be greatly appreciated.

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• Is it an good idea to make a wrapper specifically for a DateTime that respresents Now?

  - by Dirk Boer

  I have been noticing lately that is really nice to use a DateTime representing 'now' as an input parameter for your methods, for mocking and testing purposes. Instead of every method calling DateTime.UtcNow themselves, I do it once in the upper methods and forward it on the lower ones. So a lot of methods that need a 'now', have an input parameter DateTime now. (I'm using MVC, and try to detect a parameter called now and modelbind DateTime.UtcNow to it) So instead of: public bool IsStarted { get { return StartTime >= DateTime.UtcNow; } } I usually have: public bool IsStarted(DateTime now) { return StartTime >= now; } So my convention is at the moment, if a method has a DateTime parameter called now, you have to feed it with the current time. Of course this comes down to convention, and someone else can easily just throw some other DateTime in there as a parameter. To make it more solid and static-typed I am thinking about wrapping DateTime in a new object, i.e. DateTimeNow. So in one of the most upper layers I will convert the DateTime to a DateTimeNow and we will get compile errors when, someone tries to fiddle in a normal DateTime. Of course you can still workaround this, but at least if feels more that you are doing something wrong at point. Did anyone else ever went into this path? Are there any good or bad results on the long term that I am not thinking about?

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• Should Service Depend on Many Repositories, or Break Them Up?

  - by Josh Pollard

  I'm using a repository pattern for my data access. So I basically have a repository per table/class. My UI currently uses service classes to actually get things done, and these service classes wrap, and therefore depend on repositories. In many cases my services are only dependent upon one or two repositories, so things aren't too crazy. Unfortunately, one of my forms in the UI expects the user to enter data that will span five different tables. For this form I made a single service class that depends upon five repositories. Then the methods within the service for saving and loading the data call the appropriate methods on all of the corresponding repositories. As you can imagine, the save and load methods in this service are really big. Also, unit testing this service is getting really difficult because I have to setup so many fake repositories. Would it have been a better choice to break this single service apart into a few smaller services? It would put more code at the UI layer, but would make the services smaller and more testable.

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• convert a repeating code to method

  - by Mr_Green

  In my project, I am adding ComboBox, Text, Link label to my DataGridView dgvMain.I have created different methods for different cell templates as shown below: (The code below is working) gridLnklbl(string headerName) DataGridViewLinkColumn col = new DataGridViewLinkColumn(); col.HeaderText = headerName; // col.Name = "col" + headerName; // same code repeating to all the methods dgvMain.Columns.Add(col); // gridCmb(string headerName) DataGridViewComboBoxColumn col = new DataGridViewComboBoxColumn(); col.HeaderText = headerName; col.Name = "col" + headerName; dgvMain.Columns.Add(col); gridText(string headerName) DataGridViewTextBoxColumn col = new DataGridViewTextBoxColumn(); col.HeaderText = headerName; col.Name = "col" + headerName; dgvMain.Columns.Add(col); As you can see, except the declaration of objects, the code for every method is repeating. Just curious to know, can the repeating code be converted to single method? I dont know how to do that.. Its not about 3 codes of line, I have written many more lines which can be make common to those methods.

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• SPARC T4-4 Beats 8-CPU IBM POWER7 on TPC-H @3000GB Benchmark

  - by Brian

  Oracle's SPARC T4-4 server delivered a world record TPC-H @3000GB benchmark result for systems with four processors. This result beats eight processor results from IBM (POWER7) and HP (x86). The SPARC T4-4 server also delivered better performance per core than these eight processor systems from IBM and HP. Comparisons below are based upon system to system comparisons, highlighting Oracle's complete software and hardware solution. This database world record result used Oracle's Sun Storage 2540-M2 arrays (rotating disk) connected to a SPARC T4-4 server running Oracle Solaris 11 and Oracle Database 11g Release 2 demonstrating the power of Oracle's integrated hardware and software solution. The SPARC T4-4 server based configuration achieved a TPC-H scale factor 3000 world record for four processor systems of 205,792 QphH@3000GB with price/performance of $4.10/QphH@3000GB. The SPARC T4-4 server with four SPARC T4 processors (total of 32 cores) is 7% faster than the IBM Power 780 server with eight POWER7 processors (total of 32 cores) on the TPC-H @3000GB benchmark. The SPARC T4-4 server is 36% better in price performance compared to the IBM Power 780 server on the TPC-H @3000GB Benchmark. The SPARC T4-4 server is 29% faster than the IBM Power 780 for data loading. The SPARC T4-4 server is up to 3.4 times faster than the IBM Power 780 server for the Refresh Function. The SPARC T4-4 server with four SPARC T4 processors is 27% faster than the HP ProLiant DL980 G7 server with eight x86 processors on the TPC-H @3000GB benchmark. The SPARC T4-4 server is 52% faster than the HP ProLiant DL980 G7 server for data loading. The SPARC T4-4 server is up to 3.2 times faster than the HP ProLiant DL980 G7 for the Refresh Function. The SPARC T4-4 server achieved a peak IO rate from the Oracle database of 17 GB/sec. This rate was independent of the storage used, as demonstrated by the TPC-H @3000TB benchmark which used twelve Sun Storage 2540-M2 arrays (rotating disk) and the TPC-H @1000TB benchmark which used four Sun Storage F5100 Flash Array devices (flash storage). [*] The SPARC T4-4 server showed linear scaling from TPC-H @1000GB to TPC-H @3000GB. This demonstrates that the SPARC T4-4 server can handle the increasingly larger databases required of DSS systems. [*] The SPARC T4-4 server benchmark results demonstrate a complete solution of building Decision Support Systems including data loading, business questions and refreshing data. Each phase usually has a time constraint and the SPARC T4-4 server shows superior performance during each phase. [*] The TPC believes that comparisons of results published with different scale factors are misleading and discourages such comparisons. Performance Landscape The table lists the leading TPC-H @3000GB results for non-clustered systems. TPC-H @3000GB, Non-Clustered Systems System Processor P/C/T – Memory Composite(QphH) $/perf($/QphH) Power(QppH) Throughput(QthH) Database Available SPARC Enterprise M9000 3.0 GHz SPARC64 VII+ 64/256/256 – 1024 GB 386,478.3 $18.19 316,835.8 471,428.6 Oracle 11g R2 09/22/11 SPARC T4-4 3.0 GHz SPARC T4 4/32/256 – 1024 GB 205,792.0 $4.10 190,325.1 222,515.9 Oracle 11g R2 05/31/12 SPARC Enterprise M9000 2.88 GHz SPARC64 VII 32/128/256 – 512 GB 198,907.5 $15.27 182,350.7 216,967.7 Oracle 11g R2 12/09/10 IBM Power 780 4.1 GHz POWER7 8/32/128 – 1024 GB 192,001.1 $6.37 210,368.4 175,237.4 Sybase 15.4 11/30/11 HP ProLiant DL980 G7 2.27 GHz Intel Xeon X7560 8/64/128 – 512 GB 162,601.7 $2.68 185,297.7 142,685.6 SQL Server 2008 10/13/10 P/C/T = Processors, Cores, Threads QphH = the Composite Metric (bigger is better) $/QphH = the Price/Performance metric in USD (smaller is better) QppH = the Power Numerical Quantity QthH = the Throughput Numerical Quantity The following table lists data load times and refresh function times during the power run. TPC-H @3000GB, Non-Clustered Systems Database Load & Database Refresh System Processor Data Loading(h:m:s) T4Advan RF1(sec) T4Advan RF2(sec) T4Advan SPARC T4-4 3.0 GHz SPARC T4 04:08:29 1.0x 67.1 1.0x 39.5 1.0x IBM Power 780 4.1 GHz POWER7 05:51:50 1.5x 147.3 2.2x 133.2 3.4x HP ProLiant DL980 G7 2.27 GHz Intel Xeon X7560 08:35:17 2.1x 173.0 2.6x 126.3 3.2x Data Loading = database load time RF1 = power test first refresh transaction RF2 = power test second refresh transaction T4 Advan = the ratio of time to T4 time Complete benchmark results found at the TPC benchmark website http://www.tpc.org. Configuration Summary and Results Hardware Configuration: SPARC T4-4 server 4 x SPARC T4 3.0 GHz processors (total of 32 cores, 128 threads) 1024 GB memory 8 x internal SAS (8 x 300 GB) disk drives External Storage: 12 x Sun Storage 2540-M2 array storage, each with 12 x 15K RPM 300 GB drives, 2 controllers, 2 GB cache Software Configuration: Oracle Solaris 11 11/11 Oracle Database 11g Release 2 Enterprise Edition Audited Results: Database Size: 3000 GB (Scale Factor 3000) TPC-H Composite: 205,792.0 QphH@3000GB Price/performance: $4.10/QphH@3000GB Available: 05/31/2012 Total 3 year Cost: $843,656 TPC-H Power: 190,325.1 TPC-H Throughput: 222,515.9 Database Load Time: 4:08:29 Benchmark Description The TPC-H benchmark is a performance benchmark established by the Transaction Processing Council (TPC) to demonstrate Data Warehousing/Decision Support Systems (DSS). TPC-H measurements are produced for customers to evaluate the performance of various DSS systems. These queries and updates are executed against a standard database under controlled conditions. Performance projections and comparisons between different TPC-H Database sizes (100GB, 300GB, 1000GB, 3000GB, 10000GB, 30000GB and 100000GB) are not allowed by the TPC. TPC-H is a data warehousing-oriented, non-industry-specific benchmark that consists of a large number of complex queries typical of decision support applications. It also includes some insert and delete activity that is intended to simulate loading and purging data from a warehouse. TPC-H measures the combined performance of a particular database manager on a specific computer system. The main performance metric reported by TPC-H is called the TPC-H Composite Query-per-Hour Performance Metric (QphH@SF, where SF is the number of GB of raw data, referred to as the scale factor). QphH@SF is intended to summarize the ability of the system to process queries in both single and multiple user modes. The benchmark requires reporting of price/performance, which is the ratio of the total HW/SW cost plus 3 years maintenance to the QphH. A secondary metric is the storage efficiency, which is the ratio of total configured disk space in GB to the scale factor. Key Points and Best Practices Twelve Sun Storage 2540-M2 arrays were used for the benchmark. Each Sun Storage 2540-M2 array contains 12 15K RPM drives and is connected to a single dual port 8Gb FC HBA using 2 ports. Each Sun Storage 2540-M2 array showed 1.5 GB/sec for sequential read operations and showed linear scaling, achieving 18 GB/sec with twelve Sun Storage 2540-M2 arrays. These were stand alone IO tests. The peak IO rate measured from the Oracle database was 17 GB/sec. Oracle Solaris 11 11/11 required very little system tuning. Some vendors try to make the point that storage ratios are of customer concern. However, storage ratio size has more to do with disk layout and the increasing capacities of disks – so this is not an important metric in which to compare systems. The SPARC T4-4 server and Oracle Solaris efficiently managed the system load of over one thousand Oracle Database parallel processes. Six Sun Storage 2540-M2 arrays were mirrored to another six Sun Storage 2540-M2 arrays on which all of the Oracle database files were placed. IO performance was high and balanced across all the arrays. The TPC-H Refresh Function (RF) simulates periodical refresh portion of Data Warehouse by adding new sales and deleting old sales data. Parallel DML (parallel insert and delete in this case) and database log performance are a key for this function and the SPARC T4-4 server outperformed both the IBM POWER7 server and HP ProLiant DL980 G7 server. (See the RF columns above.) See Also Transaction Processing Performance Council (TPC) Home Page Ideas International Benchmark Page SPARC T4-4 Server oracle.com OTN Oracle Solaris oracle.com OTN Oracle Database 11g Release 2 Enterprise Edition oracle.com OTN Sun Storage 2540-M2 Array oracle.com OTN Disclosure Statement TPC-H, QphH, $/QphH are trademarks of Transaction Processing Performance Council (TPC). For more information, see www.tpc.org. SPARC T4-4 205,792.0 QphH@3000GB, $4.10/QphH@3000GB, available 5/31/12, 4 processors, 32 cores, 256 threads; IBM Power 780 QphH@3000GB, 192,001.1 QphH@3000GB, $6.37/QphH@3000GB, available 11/30/11, 8 processors, 32 cores, 128 threads; HP ProLiant DL980 G7 162,601.7 QphH@3000GB, $2.68/QphH@3000GB available 10/13/10, 8 processors, 64 cores, 128 threads.

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• More Fun With Math

  - by PointsToShare

  More Fun with Math   The runaway student – three different ways of solving one problem Here is a problem I read in a Russian site: A student is running away. He is moving at 1 mph. Pursuing him are a lion, a tiger and his math teacher. The lion is 40 miles behind and moving at 6 mph. The tiger is 28 miles behind and moving at 4 mph. His math teacher is 30 miles behind and moving at 5 mph. Who will catch him first? Analysis Obviously we have a set of three problems. They are all basically the same, but the details are different. The problems are of the same class. Here is a little excursion into computer science. One of the things we strive to do is to create solutions for classes of problems rather than individual problems. In your daily routine, you call it re-usability. Not all classes of problems have such solutions. If a class has a general (re-usable) solution, it is called computable. Otherwise it is unsolvable. Within unsolvable classes, we may still solve individual (some but not all) problems, albeit with different approaches to each. Luckily the vast majority of our daily problems are computable, and the 3 problems of our runaway student belong to a computable class. So, let’s solve for the catch-up time by the math teacher, after all she is the most frightening. She might even make the poor runaway solve this very problem – perish the thought! Method 1 – numerical analysis. At 30 miles and 5 mph, it’ll take her 6 hours to come to where the student was to begin with. But by then the student has advanced by 6 miles. 6 miles require 6/5 hours, but by then the student advanced by another 6/5 of a mile as well. And so on and so forth. So what are we to do? One way is to write code and iterate it until we have solved it. But this is an infinite process so we’ll end up with an infinite loop. So what to do? We’ll use the principles of numerical analysis. Any calculator – your computer included – has a limited number of digits. A double floating point number is good for about 14 digits. Nothing can be computed at a greater accuracy than that. This means that we will not iterate ad infinidum, but rather to the point where 2 consecutive iterations yield the same result. When we do financial computations, we don’t even have to go that far. We stop at the 10th of a penny.  It behooves us here to stop at a 10th of a second (100 milliseconds) and this will how we will avoid an infinite loop. Interestingly this alludes to the Zeno paradoxes of motion – in particular “Achilles and the Tortoise”. Zeno says exactly the same. To catch the tortoise, Achilles must always first come to where the tortoise was, but the tortoise keeps moving – hence Achilles will never catch the tortoise and our math teacher (or lion, or tiger) will never catch the student, or the policeman the thief. Here is my resolution to the paradox. The distance and time in each step are smaller and smaller, so the student will be caught. The only thing that is infinite is the iterative solution. The race is a convergent geometric process so the steps are diminishing, but each step in the solution takes the same amount of effort and time so with an infinite number of steps, we’ll spend an eternity solving it.  This BTW is an original thought that I have never seen before. But I digress. Let’s simply write the code to solve the problem. To make sure that it runs everywhere, I’ll do it in JavaScript. function LongCatchUpTime(D, PV, FV) // D is Distance; PV is Pursuers Velocity; FV is Fugitive’ Velocity {     var t = 0;     var T = 0;     var d = parseFloat(D);     var pv = parseFloat (PV);     var fv = parseFloat (FV);     t = d / pv;     while (t > 0.000001) //a 10th of a second is 1/36,000 of an hour, I used 1/100,000     {         T = T + t;         d = t * fv;         t = d / pv;     }     return T;     } By and large, the higher the Pursuer’s velocity relative to the fugitive, the faster the calculation. Solving this with the 10th of a second limit yields: 7.499999232000001 Method 2 – Geometric Series. Each step in the iteration above is smaller than the next. As you saw, we stopped iterating when the last step was small enough, small enough not to really matter.  When we have a sequence of numbers in which the ratio of each number to its predecessor is fixed we call the sequence geometric. When we are looking at the sum of sequence, we call the sequence of sums series.  Now let’s look at our student and teacher. The teacher runs 5 times faster than the student, so with each iteration the distance between them shrinks to a fifth of what it was before. This is a fixed ratio so we deal with a geometric series.  We normally designate this ratio as q and when q is less than 1 (0 < q < 1) the sum of  + … +  is  – 1) / (q – 1). When q is less than 1, it is easier to use ) / (1 - q). Now, the steps are 6 hours then 6/5 hours then 6/5*5 and so on, so q = 1/5. And the whole series is multiplied by 6. Also because q is less than 1 , 1/  diminishes to 0. So the sum is just  / (1 - q). or 1/ (1 – 1/5) = 1 / (4/5) = 5/4. This times 6 yields 7.5 hours. We can now continue with some algebra and take it back to a simpler formula. This is arduous and I am not going to do it here. Instead let’s do some simpler algebra. Method 3 – Simple Algebra. If the time to capture the fugitive is T and the fugitive travels at 1 mph, then by the time the pursuer catches him he travelled additional T miles. Time is distance divided by speed, so…. (D + T)/V = T  thus D + T = VT  and D = VT – T = (V – 1)T  and T = D/(V – 1) This “strangely” coincides with the solution we just got from the geometric sequence. This is simpler ad faster. Here is the corresponding code. function ShortCatchUpTime(D, PV, FV) {     var d = parseFloat(D);     var pv = parseFloat (PV);     var fv = parseFloat (FV);     return d / (pv - fv); } The code above, for both the iterative solution and the algebraic solution are actually for a larger class of problems.  In our original problem the student’s velocity (speed) is 1 mph. In the code it may be anything as long as it is less than the pursuer’s velocity. As long as PV > FV, the pursuer will catch up. Here is the really general formula: T = D / (PV – FV) Finally, let’s run the program for each of the pursuers.  It could not be worse. I know he’d rather be eaten alive than suffering through yet another math lesson. See the code run? Select  “Catch Up Time” in www.mgsltns.com/games.htm The host is running on Unix, so the link is case sensitive. That’s All Folks

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• WMI Rights required to read root\MicrosoftIISv2 in IIS7 with IIS6 compatibility mode

  - by JoeBilly

  I need to manage my IIS7 (Windows Server 2008) remotely with a WMI IIS6 API. So I added the IIS6 WMI Compatibility and IIS6 Metabase Compatibility roles to access the root\MicrosoftIIsv2 namespace. I have a domain account which is not administrator on the remote machine ; with this right, everything is ok. I configured these rights for my domain account to access the root\MicrosoftIIsv2 WMI namespace remotely ; note that these rights work perfectly on a IIS6 and Windows Server 2003 : DCOM : Account in Distributed COM Users Remote & local access to DCOM WMI : Root\CIMV2 (I need access here too) Execute methods, Enable Account, Remote Enable Root\Default (I need access here too) Execute methods, Enable Account, Remote Enable Root\MicrosoftIISv2 Execute methods, Enable Account, Provider Write, Remote Enable IIS Metabase (Metabase Explorer) : LM Full Control (W3SVC inherits these permissions) I tried to give some access on C:\Windows\System32\inetsrv too ; don't know if needed. My issue is : I can't list the IIS WebSites (\root\MicrosoftIISv2:IIsWebServerSetting.Name="W3SVC/*"). I don't get an 'access denied' but nothing is returned. My API and powershell tests can connect and execute queries in the root\MicrosoftIISv2 namespace I can read the IIsComputer class ex: Get-WmiObject IIsComputer -namespace "ROOT\MicrosoftIISv2" -authentication PacketPrivacy | SELECT * I can't read the IIsWebServerSetting, IIsWebServer ... to list the WebSites : the query returns an empty collection ex: Get-WmiObject IIsWebServerSetting -namespace "ROOT\MicrosoftIISv2" -authentication PacketPrivacy | SELECT ServerComment All queries work perfectly if the account is administrator as already said I am using PacketPrivacy authentication FI: I got a Warning Event 5605 with the Administrator right or not, that does not seem to have an impact : The root\MicrosoftIISv2 namespace is marked with the RequiresEncryption flag. Access to this namespace might be denied if the script or application does not have the appropriate authentication level. Change the authentication level to Pkt_Privacy and run the script or application again Ok, I have some more informations, when I use IIS 6 Metabase Explorer with my administrator account I can see the rights are correctly inherited for my non-administrator account. But when I try to connect using my non-administrator account, I can list the LM node, but get an "access denied, failed to get a key's data" when I try to browse the child nodes. I'll check further. I tried to Trace the WMI Activity, and everything seems OK ; this tends to confirm that the problem lies in IIS Rights.

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• Mac OS X Server Configure DHCP Options 66 and 67

  - by Paul Adams

  I need to configure Mountain Lion (10.8.2) OS X Server BOOTP to provide DHCP options 66 and 67 to provide PXE booting for PCs on my network. I have tried following the bootpd MAN pages, but they are not specific enough. I have also read conflicting information on the net, but nothing definitive for Mountain Lion DHCP. From bootpd man page: bootpd has a built-in type conversion table for many more options, mostly those specified in RFC 2132, and will try to convert from whatever type the option appears in the property list to the binary, packet format. For example, if bootpd knows that the type of the option is an IP address or list of IP addresses, it converts from the string form of the IP address to the binary, network byte order numeric value. If the type of the option is a numeric value, it converts from string, integer, or boolean, to the proper sized, network byte-order numeric value. Regardless of whether bootpd knows the type of the option or not, you can always specify the DHCP option using the data property list type <key>dhcp_option_128</key> <data> AAqV1Tzo </data> My TFTP server is 172.16.152.20 and the bootfile is pxelinux.0 I have edited /etc/bootpd.plist and added the following to the subnet dict: <key>dhcp_option_66</key> <data> LW4gLWUgrBCYFAo= </data> <key>dhcp_option_67</key> <data> LW4gLWUgcHhlbGludXguMAo= </data> According to the man page, the data elements are supposed to be Base64 encoded, but no matter what I try, I cannot get PXE clients to boot. I have tried encoding 172.16.152.20 using various methods: echo "172.16.152.20" | openssl enc -base64 returns MTcyLjE2LjE1Mi4yMAo= DHCP Option Code Utility (http://mac.softpedia.com/get/Internet-Utilities/DHCP-Option-Code-Utility.shtml) generating a string from 172.16.152.20 yields: LW4gLWUgMTcyLjE2LjE1Mi4yMAo= (used in the above example) DHCP Option Code Utility generating an IP Addresss from 172.16.152.20 yields: LW4gLWUgrBCYFAo= Encoding pxelinux.0 with the above methods likewise yields different encodings. I have tried using all three methods of encoding the data elements, but nothing seems to work i.e. my PXE boot clients do not get directed to my TFTP server. Can anyone help? Regards, Paul Adams.

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• Best way to migrate from IIS6 to IIS6

  - by darko-romanov

  Hi, I need to move all my sites on a server with IIS 6 to another one, that has same OS (Windows Server 20003) and same IIS version. I'm trying to understand which is the best way to do it. Searching on Google I've found that there are at least 2 methods, one uses IIS Migration Tool, and another Web Deployment Tool. I don't know which method is best, it also seems that both methods can export one site at once, and I have about 100 sites hosted. What would you do?

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• NPS EAP authentication failing after Windows Update

  - by sqlreader

  I have a Windows 2008 Std server running NPS. After applying the latest round of updates (including Root Certificates for April 2012 KB931125 (See:http://support.microsoft.com/kb/933430/)), EAP authentication is failing due to being malformed. Sample error (Security/Event ID 6273), truncated for brevity: Authentication Details: Proxy Policy Name: Use Windows authentication for all users Network Policy Name: Wireless Access Authentication Provider: Windows Authentication Server: nps-host.corp.contoso.com Authentication Type: PEAP EAP Type: - Account Session Identifier: - Reason Code: 266 Reason: The message received was unexpected or badly formatted. The NPS policy (Wireless Access) is configured accordingly (for Constraints/Authentication methods) EAP Types: Microsoft: Protected EAP (PEAP) - with a valid certificate from ADCS Microsoft: Secured password (EAP-MSCHAP v2) Less secure authentication methods: Microsoft Encrypted Authentication version 2 (MS-CHAP-v2) User can change password after it has expired Microsoft Encrypted Authentication (MS-CHAP) User can change password after it has expired We've tested a different RADIUS server without the aforementioned patch, and removed EAP as an authentication type and experienced success. Has anyone else experienced this issue?

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• DD-WRT with native IPv6

  - by Matt

  My ISP provides native IPv6 support (ie. I can plug in my computer straight into the WAN and get an IPv6 address). However I can not get this working on DD-WRT. When I enable IPv6 and radvd in DD-WRT, the router gets in IPv6 address, but the devices on my LAN do not. I tried looking at the DD-WRT wiki, but this only displayed instructions for tunneling or other methods where native support isn't available. I found a small amount of sites thorough searching, but none of the methods these sites described gave my computers each a global IPv6 address. In addition, SSHing into the router using ping6 on sites such as ipv6.google.com causes "host unreachable" errors. Has anyone using DD-WRT configured a successful setup with native IPv6? I am using a Netgear WNDR3700 v2, with DD-WRT build 17201

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• How to properly add .NET assemblies to Powershell session?

  - by amandion

  I have a .NET assembly (a dll) which is an API to backup software we use here. It contains some properties and methods I would like to take advantage of in my Powershell script(s). However, I am running into a lot of issues with first loading the assembly, then using any of the types once the assembly is loaded. The complete file path is: C:\rnd\CloudBerry.Backup.API.dll In Powershell I use: $dllpath = "C:\rnd\CloudBerry.Backup.API.dll" Add-Type -Path $dllpath I get the error below: Add-Type : Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information. At line:1 char:9 + Add-Type <<<< -Path $dllpath + CategoryInfo : NotSpecified: (:) [Add-Type], ReflectionTypeLoadException + FullyQualifiedErrorId : System.Reflection.ReflectionTypeLoadException,Microsoft.PowerShell.Commands.AddTypeComma ndAdd-Type : Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information. Using the same cmdlet on another .NET assembly, DotNetZip, which has examples of using the same functionality on the site also does not work for me. I eventually find that I am seemingly able to load the assembly using reflection: [System.Reflection.Assembly]::LoadFrom($dllpath) Although I don't understand the difference between the methods Load, LoadFrom, or LoadFile that last method seems to work. However, I still seem to be unable to create instances or use objects. Each time I try, I get errors that describe that Powershell is unable to find any of the public types. I know the classes are there: $asm = [System.Reflection.Assembly]::LoadFrom($dllpath) $cbbtypes = $asm.GetExportedTypes() $cbbtypes | Get-Member -Static ---- start of excerpt ---- TypeName: CloudBerryLab.Backup.API.BackupProvider Name MemberType Definition ---- ---------- ---------- PlanChanged Event System.EventHandler`1[CloudBerryLab.Backup.API.Utils.ChangedEventArgs] PlanChanged(Sy... PlanRemoved Event System.EventHandler`1[CloudBerryLab.Backup.API.Utils.PlanRemoveEventArgs] PlanRemoved... CalculateFolderSize Method static long CalculateFolderSize() Equals Method static bool Equals(System.Object objA, System.Object objB) GetAccounts Method static CloudBerryLab.Backup.API.Account[], CloudBerry.Backup.API, Version=1.0.0.1, Cu... GetBackupPlans Method static CloudBerryLab.Backup.API.BackupPlan[], CloudBerry.Backup.API, Version=1.0.0.1,... ReferenceEquals Method static bool ReferenceEquals(System.Object objA, System.Object objB) SetProfilePath Method static System.Void SetProfilePath(string profilePath) ----end of excerpt---- Trying to use static methods fail, I don't know why!!! [CloudBerryLab.Backup.API.BackupProvider]::GetAccounts() Unable to find type [CloudBerryLab.Backup.API.BackupProvider]: make sure that the assembly containing this type is load ed. At line:1 char:42 + [CloudBerryLab.Backup.API.BackupProvider] <<<< ::GetAccounts() + CategoryInfo : InvalidOperation: (CloudBerryLab.Backup.API.BackupProvider:String) [], RuntimeException + FullyQualifiedErrorId : TypeNotFound Any guidance appreciated!!

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