temporary objects - Page 90

MS Access 2007 doesn't allow to group form objects anymore like in 2003 ?

- by asksuperuser

It's a long time I haven't looked at MS Access but I clearly remembered it was possible to select multiple objects (lines, textbox, etc.) and type Ctrl + G to group them. In Access 2007 I can't make it work and I can't find any context menu to do so. Has this feature been erased by MS ?

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How can you procedurally place objects in a non-gridded game?

- by nickbadal

This is a follow-up question to this question. I mistakenly worded the question, but got a good answer before I could correct myself, so I didn't want to delete it. Sorry! Now that I know that it is possible, I'd like to implement procedural world generation, but I don't want it to look gridded or blocky, where everything is obviously placed on an integer grid. I know that you can do this in gridded worlds by inputting a square's x and y into a noise function, or similar, but how can I generate a more natural looking object placement using procedural methods? This is in the context of an adventure game, if it matters.

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Static vs. dynamic memory allocation - lots of constant objects, only small part of them used at runtime

- by k29

Here are two options: Option 1: enum QuizCategory { CATEGORY_1(new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...), CATEGORY_2(new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...), ... ; public MyCollection<Question> collection; private QuizCategory(MyCollection<Question> collection) { this.collection = collection; } public Question getRandom() { return collection.getRandomQuestion(); } } Option 2: enum QuizCategory2 { CATEGORY_1 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...; } }, CATEGORY_2 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...; } }; public Question getRandom() { MyCollection<Question> collection = populateWithQuestions(); return collection.getRandomQuestion(); } protected abstract MyCollection<Question> populateWithQuestions(); } There will be around 1000 categories, each containing 10 - 300 questions (100 on average). At runtime typically only 10 categories and 30 questions will be used. Each question is itself an enum constant (with its fields and methods). I'm trying to decide between those two options in the mobile application context. I haven't done any measurements since I have yet to write the questions and would like to gather more information before committing to one or another option. As far as I understand: (a) Option 1 will perform better since there will be no need to populate the collection and then garbage-collect the questions; (b) Option 1 will require extra memory: 1000 categories x 100 questions x 4 bytes for each reference = 400 Kb, which is not significant. So I'm leaning to Option 1, but just wondered if I'm correct in my assumptions and not missing something important? Perhaps someone has faced a similar dilemma? Or perhaps it doesn't actually matter that much?

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Did Bjarne Stroustrup create the terms constructor/destructor when talking about objects?

- by user104971

I was watching this keynote and Bjarne Stroustrup (Creator of C++) claims that he hadn't yet invented the words constructor and destructor yet when he was giving an example of RAII. http://www.youtube.com/watch?v=IYBLXBJr0HU I know the concept of construction and destruction has been around a lot longer (even in C, a function that allocates and returns a struct and then a function that frees it etc.), but was Bjarne really the first to invent the terms?

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Can I retrieve objects from a complex query that limits results to fields from a single table?

- by Sean Redmond

I have a model whose rows I always want to sort based on the values in another associated model and I was thinking that the way to implement this would be to use set_dataset in the model. This is causing query results to be returned as hashes rather than objects, though, so none of the methods from the class can be used when iterating over the dataset. I basically have two classes class SortFields < Sequel::Model(:sort_fields) set_primary_key :objectid end class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid end Some backstory: the data is imported from a legacy system into mysql. The values in sort_fields are calculated from multiple other associated tables (some one-to-many, some many-to-many) according to some complicated rules. The likely solution will be to just add the values in sort_fields to items (I want to keep the imported data separate from the calculated data, but I don't have to). First, though, I just want to understand how far you can go with a dataset and still get objects rather than hashes. If I set the dataset to sort on a field in items like so class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset(order(:sortnumber)) end then the expected clause is added to the generated SQL, e.g.: >> Items.limit(1).sql => "SELECT * FROM `items` ORDER BY `sortnumber` LIMIT 1" and queries still return objects: >> Items.limit(1).first.class => Items If I order it by the associated fields though... class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). order(:sort1, :sort2, :sort3) ) end ...I get hashes ?> Items.limit(1).first.class => Hash My first thought was that this happens because all fields from sort_fields are included in the results and maybe if selected only the fields from items I would get Items objects again: class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). select(:items.*). order(:sort1, :sort2, :sort3) ) end The generated SQL is what I would expect: >> Items.limit(1).sql => "SELECT `items`.* FROM `items` LEFT OUTER JOIN `sort_fields` ON (`sort_fields`.`objectid` = `items`.`objectid`) ORDER BY `sort1`, `sort2`, `sort3` LIMIT 1" It returns the same rows as the set_dataset(order(:sortnumber)) version but it still doesn't work: >> Items.limit(1).first.class => Hash Before I add the sort fields to the items table so that they can all live happily in the same model, is there a way to tell Sequel to return on object when it wants to return a hash?

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How can I make the storage of C++ lambda objects more efficient?

- by Peter Ruderman

I've been thinking about storing C++ lambda's lately. The standard advice you see on the Internet is to store the lambda in a std::function object. However, none of this advice ever considers the storage implications. It occurred to me that there must be some seriously black voodoo going on behind the scenes to make this work. Consider the following class that stores an integer value: class Simple { public: Simple( int value ) { puts( "Constructing simple!" ); this->value = value; } Simple( const Simple& rhs ) { puts( "Copying simple!" ); this->value = rhs.value; } Simple( Simple&& rhs ) { puts( "Moving simple!" ); this->value = rhs.value; } ~Simple() { puts( "Destroying simple!" ); } int Get() const { return this->value; } private: int value; }; Now, consider this simple program: int main() { Simple test( 5 ); std::function<int ()> f = [test] () { return test.Get(); }; printf( "%d\n", f() ); } This is the output I would hope to see from this program: Constructing simple! Copying simple! Moving simple! Destroying simple! 5 Destroying simple! Destroying simple! First, we create the value test. We create a local copy on the stack for the temporary lambda object. We then move the temporary lambda object into memory allocated by std::function. We destroy the temporary lambda. We print our output. We destroy the std::function. And finally, we destroy the test object. Needless to say, this is not what I see. When I compile this on Visual C++ 2010 (release or debug mode), I get this output: Constructing simple! Copying simple! Copying simple! Copying simple! Copying simple! Destroying simple! Destroying simple! Destroying simple! 5 Destroying simple! Destroying simple! Holy crap that's inefficient! Not only did the compiler fail to use my move constructor, but it generated and destroyed two apparently superfluous copies of the lambda during the assignment. So, here finally are the questions: (1) Is all this copying really necessary? (2) Is there some way to coerce the compiler into generating better code? Thanks for reading!

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ASP.NET exception gives irrelevant stack trace on YSOD, very challenging!

- by pootow

Here is the YSOD: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SqlException (0x80131904): Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.] System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +428 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 ECommerce.PMethod.Sql.SqlConns.Open() +78 ECommerce.PMethod.Sql.SqlConns..ctor() +120 ECommerce.login.DatasInfo.Proc.UserCenter.IsLogin(String UserGUID, Int32 UserID) +49 ECommerce.login.Rules.Users.UserLogin.isLogin() +44 Config.isUserLogined() +5 Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627 [TypeInitializationException: The type initializer for 'ECommerce.ERP.DAL.DBConn' threw an exception.] ECommerce.ERP.DAL.DBConn.get_ConnString() +0 [ObjectDefinitionStoreException: Factory method 'System.String get_ConnString()' threw an Exception.] Spring.Objects.Factory.Support.SimpleInstantiationStrategy.Instantiate(RootObjectDefinition definition, String name, IObjectFactory factory, MethodInfo factoryMethod, Object[] arguments) +257 Spring.Objects.Factory.Support.ConstructorResolver.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +624 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +60 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +56 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +436 [ObjectCreationException: Error thrown by a dependency of object 'styleService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 56' : Initialization of object failed : Factory method 'System.String get_ConnString()' threw an Exception. while resolving 'constructor argument with name promotionservice' to 'promotionService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 31' while resolving 'constructor argument with name domainservice' to 'promotionDomainService' defined in 'assembly [ECommerce.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Domain.AppContext.xml] line 20' while resolving 'constructor argument with name promotionrepos' to 'promotionRepos' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34' while resolving 'constructor argument with name connstr' to 'ECommerce.ERP.DAL.DBConn#389F399' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34'] Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveReference(IObjectDefinition definition, String name, String argumentName, RuntimeObjectReference reference) +394 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolvePropertyValue(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +312 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveValueIfNecessary(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +17 Spring.Objects.Factory.Support.ConstructorResolver.ResolveConstructorArguments(String objectName, RootObjectDefinition definition, ObjectWrapper wrapper, ConstructorArgumentValues cargs, ConstructorArgumentValues resolvedValues) +993 Spring.Objects.Factory.Support.ConstructorResolver.AutowireConstructor(String objectName, RootObjectDefinition rod, ConstructorInfo[] chosenCtors, Object[] explicitArgs) +171 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.AutowireConstructor(String name, RootObjectDefinition definition, ConstructorInfo[] ctors, Object[] explicitArgs) +65 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +161 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +636 Spring.Objects.Factory.Support.AbstractObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +174 Spring.Objects.Factory.Support.WebObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +150 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObjectInternal(String name, Type requiredType, Object[] arguments, Boolean suppressConfigure) +990 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObject(String name) +10 Spring.Context.Support.AbstractApplicationContext.GetObject(String name) +20 ECommerce.Common.ServiceLocator.GetService() +334 ECommerce.Mvc.Controllers.StylesController..ctor() +72 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +80 [InvalidOperationException: An error occurred when trying to create a controller of type 'ECommerce.Mvc.Controllers.StylesController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +190 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +68 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +118 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +46 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +63 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +13 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8677954 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 Question is: the first stack trace is irrelevant to others, what happened? Any ideas? Let me make this more clear: a MVC page uses the spring part trying to load a lazy-init service which constructor wants a connection string through a static property like this: <object id="promotionRepos" type="ECommerce.Data.AdoNet.Promotions.PromotionRepos, ECommerce.Data.AdoNet" lazy-init="true"> <constructor-arg name="provider"> <null /> </constructor-arg> <constructor-arg name="connStr"> <object type="ECommerce.ERP.DAL.DBConn, ECommerce.ERP.DAL" factory-method="get_ConnString" /> </constructor-arg> <property name="RefreshInterval" value="00:00:10" /> </object> the timeout part is some what irrelevent to all others. see this in the first exception: Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 it's another page at all. And also, ECommerce.PMethod.Sql.SqlConns.Open() uses its own connection string, not the one loaded by spring, it's different module from diffrent team. And I am sure the connection string is correct. And, this ysod cames up randomly. Sometimes nothing is wrong, and sometimes, it appears. I thought there could be something wrong with my database or the network/firewall, I will check it later, but now I want understand this tricky stack trace.

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Building "isolated" and "automatically updated" caches (java.util.List) in Java.

- by Aidos

Hi Guys, I am trying to write a framework which contains a lot of short-lived caches created from a long-living cache. These short-lived caches need to be able to return their entier contents, which is a clone from the original long-living cache. Effectively what I am trying to build is a level of transaction isolation for the short-lived caches. The user should be able to modify the contents of the short-lived cache, but changes to the long-living cache should not be propogated through (there is also a case where the changes should be pushed through, depending on the Cache type). I will do my best to try and explain: master-cache contains: [A,B,C,D,E,F] temporary-cache created with state [A,B,C,D,E,F] 1) temporary-cache adds item G: [A,B,C,D,E,F] 2) temporary-cache removes item B: [A,C,D,E,F] master-cache contains: [A,B,C,D,E,F] 3) master-cache adds items [X,Y,Z]: [A,B,C,D,E,F,X,Y,Z] temporary-cache contains: [A,C,D,E,F] Things get even harder when the values in the items can change and shouldn't always be updated (so I can't even share the underlying object instances, I need to use clones). I have implemented the simple approach of just creating a new instance of the List using the standard Collection constructor on ArrayList, however when you get out to about 200,000 items the system just runs out of memory. I know the value of 200,000 is excessive to iterate, but I am trying to stress my code a bit. I had thought that it might be able to somehow "proxy" the list, so the temporary-cache uses the master-cache, and stores all of it's changes (effectively a Memento for the change), however that quickly becomes a nightmare when you want to iterate the temporary-cache, or retrieve an item at a specific index. Also given that I want some modifications to the contents of the list to come through (depending on the type of the temporary-cache, whether it is "auto-update" or not) and I get completly out of my depth. Any pointers to techniques or data-structures or just general concepts to try and research will be greatly appreciated. Cheers, Aidos

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My architecture has a problem with views that required information from different objects. How can I solve this?

- by Oscar

I am building an architecture like this: These are my SW layers ______________ | | | Views | |______________| ______________ | | |Business Logic| |______________| ______________ | | | Repository | |______________| My views are going to generate my HTML to be sent to the user Business logic is where all the business logics are Repository is a layer to access the DB My idea is that the repository uses entities (that are basically the representation of the tables, in order to perform DB queries. The layers communicate between themselves using Business Objects, that are objects that represent the real-world-object itself. They can contain business rules and methods. The views build/use DTOs, they are basically objects that have the information required to be shown on the screen. They expect also this kind of object on actions and, before calling the business logic, they create BO. First question: what is your overall feeling about this architecture? I've used similar architecture for some projects and I always got this problem: If my view has this list to show : Student1, age, course, Date Enrolled, Already paid? It has information from different BO. How do you think one should build the structure? These were the alternatives I could think of: The view layer could call the methods to get the student, then the course it studies, then the payment information. This would cause a lot of DB accesses and my view would have the knowledge about how to act to generate this information. This just seems wrong for me. I could have an "adapter object", that has the required information (a class that would have a properties Student, Course and Payment). But I would required one adapter object for each similar case, this may get very bad for big projects. I still don't like them. Would you have ideas? How would you change the architecture to avoid this kind of problems? @Rory: I read the CQRS and I don't think this suits my needs. As taken from a link references in your link Before describing the details of CQRS we need to understand the two main driving forces behind it: collaboration and staleness That means: many different actors using the same object (collaboration) and once data has been shown to a user, that same data may have been changed by another actor – it is stale (staleness). My problem is that I want to show to the user information from different BO, so I would need to receive them from the service layer. How can my service layer assemble and deliver this information? Edit to @AndrewM: Yes, you understood it correctly, the original idea was to have the view layer to build the BOs, but you have a very nice point about the creation of the BO inside the business layers. Assuming I follow your advice and move the creation logic inside the business layer, my business layer interface would contain the DTOs, for instance public void foo(MyDTO object) But as far as I understand, the DTO is tightly coupled to each view, so it would not be reusable by a second view. In order to use it, the second view would need to build a specific DTO from a specific view or I would have to duplicate the code in the business layer. Is this correct or am I missing something?

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Boost your infrastructure with Coherence into the Cloud

- by Nino Guarnacci

Authors: Nino Guarnacci & Francesco Scarano, at this URL could be found the original article: http://blogs.oracle.com/slc/coherence_into_the_cloud_boost. Thinking about the enterprise cloud, come to mind many possible configurations and new opportunities in enterprise environments. Various customers needs that serve as guides to this new trend are often very different, but almost always united by two main objectives: Elasticity of infrastructure both Hardware and Software Investments related to the progressive needs of the current infrastructure Characteristics of innovation and economy. A concrete use case that I worked on recently demanded the fulfillment of two basic requirements of economy and innovation.The client had the need to manage a variety of data cache, which can process complex queries and parallel computational operations, maintaining the caches in a consistent state on different server instances, on which the application was installed.In addition, the customer was looking for a solution that would allow him to manage the likely situations in load peak during certain times of the year.For this reason, the customer requires a replication site, on which convey part of the requests during periods of peak; the desire was, however, to prevent the immobilization of investments in owned hardware-software architectures; so, to respond to this need, it was requested to seek a solution based on Cloud technologies and architectures already offered by the market. Coherence can already now address the requirements of large cache between different nodes in the cluster, providing further technology to search and parallel computing, with the simultaneous use of all hardware infrastructure resources. Moreover, thanks to the functionality of "Push Replication", which can replicate and update the information contained in the cache, even to a site hosted in the cloud, it is satisfied the need to make resilient infrastructure that can be based also on nodes temporarily housed in the Cloud architectures. There are different types of configurations that can be realized using the functionality "Push-Replication" of Coherence. Configurations can be either: Active - Passive Hub and Spoke Active - Active Multi Master Centralized Replication Whereas the architecture of this particular project consists of two sites (Site 1 and Site Cloud), between which only Site 1 is enabled to write into the cache, it was decided to adopt an Active-Passive Configuration type (Hub and Spoke). If, however, the requirement should change over time, it will be particularly easy to change this configuration in an Active-Active configuration type. Although very simple, the small sample in this post, inspired by the specific project is effective, to better understand the features and capabilities of Coherence and its configurations. Let's create two distinct coherence cluster, located at miles apart, on two different domain contexts, one of them "hosted" at home (on-premise) and the other one hosted by any cloud provider on the network (or just the same laptop to test it :)). These two clusters, which we call Site 1 and Site Cloud, will contain the necessary information, so a simple client can insert data only into the Site 1. On both sites will be subscribed a listener, who listens to the variations of specific objects within the various caches. To implement these features, you need 4 simple classes: CachedResponse.java Represents the POJO class that will be inserted into the cache, and fulfills the task of containing useful information about the hypothetical links navigation ResponseSimulatorHelper.java Represents a link simulator, which has the task of randomly creating objects of type CachedResponse that will be added into the caches CacheCommands.java Represents the model of our example, because it is responsible for receiving instructions from the controller and performing basic operations against the cache, such as insert, delete, update, listening, objects within the cache Shell.java It is our controller, which give commands to be executed within the cache of the two Sites So, summarily, we execute the java class "Shell", asking it to put into the cache 100 objects of type "CachedResponse" through the java class "CacheCommands", then the simulator "ResponseSimulatorHelper" will randomly create new instances of objects "CachedResponse ". Finally, the Shell class will listen to for events occurring within the cache on the Site Cloud, while insertions and deletions are performed on Site 1. Now, we realize the two configurations of two respective sites / cluster: Site 1 and Site Cloud.For the Site 1 we define a cache of type "distributed" with features of "read and write", using the cache class store for the "push replication", a functionality offered by the project "incubator" of Oracle Coherence.For the "Site Cloud" we expect even the definition of “distributed” cache type with tcp proxy feature enabled, so it can receive updates from Site 1. Coherence Cache Config XML file for "storage node" on "Site 1" site1-prod-cache-config.xml Coherence Cache Config XML file for "storage node" on "Site Cloud" site2-prod-cache-config.xml For two clients "Shell" which will connect respectively to the two clusters we have provided two easy access configurations. Coherence Cache Config XML file for Shell on "Site 1" site1-shell-prod-cache-config.xml Coherence Cache Config XML file for Shell on "Site Cloud" site2-shell-prod-cache-config.xml Now, we just have to get everything and run our tests. To start at least one "storage" node (which holds the data) for the "Cloud Site", we can run the standard class provided OOTB by Oracle Coherence com.tangosol.net.DefaultCacheServer with the following parameters and values:-Xmx128m-Xms64m-Dcom.sun.management.jmxremote -Dtangosol.coherence.management=all -Dtangosol.coherence.management.remote=true -Dtangosol.coherence.distributed.localstorage=true -Dtangosol.coherence.cacheconfig=config/site2-prod-cache-config.xml-Dtangosol.coherence.clusterport=9002-Dtangosol.coherence.site=SiteCloud To start at least one "storage" node (which holds the data) for the "Site 1", we can perform again the standard class provided by Coherence com.tangosol.net.DefaultCacheServer with the following parameters and values:-Xmx128m-Xms64m-Dcom.sun.management.jmxremote -Dtangosol.coherence.management=all -Dtangosol.coherence.management.remote=true -Dtangosol.coherence.distributed.localstorage=true -Dtangosol.coherence.cacheconfig=config/site1-prod-cache-config.xml-Dtangosol.coherence.clusterport=9001-Dtangosol.coherence.site=Site1 Then, we start the first client "Shell" for the "Cloud Site", launching the java class it.javac.Shell using these parameters and values: -Xmx64m-Xms64m-Dcom.sun.management.jmxremote -Dtangosol.coherence.management=all -Dtangosol.coherence.management.remote=true -Dtangosol.coherence.distributed.localstorage=false -Dtangosol.coherence.cacheconfig=config/site2-shell-prod-cache-config.xml-Dtangosol.coherence.clusterport=9002-Dtangosol.coherence.site=SiteCloud Finally, we start the second client "Shell" for the "Site 1", re-launching a new instance of class it.javac.Shell using the following parameters and values: -Xmx64m-Xms64m-Dcom.sun.management.jmxremote -Dtangosol.coherence.management=all -Dtangosol.coherence.management.remote=true -Dtangosol.coherence.distributed.localstorage=false -Dtangosol.coherence.cacheconfig=config/site1-shell-prod-cache-config.xml-Dtangosol.coherence.clusterport=9001-Dtangosol.coherence.site=Site1 And now, let’s execute some tests to validate and better understand our configuration. TEST 1The purpose of this test is to load the objects into the "Site 1" cache and seeing how many objects are cached on the "Site Cloud". Within the "Shell" launched with parameters to access the "Site 1", let’s write and run the command: load test/100 Within the "Shell" launched with parameters to access the "Site Cloud" let’s write and run the command: size passive-cache Expected result If all is OK, the first "Shell" has uploaded 100 objects into a cache named "test"; consequently the "push-replication" functionality has updated the "Site Cloud" by sending the 100 objects to the second cluster where they will have been posted into a respective cache, which we named "passive-cache". TEST 2The purpose of this test is to listen to deleting and adding events happening on the "Site 1" and that are replicated within the cache on "Cloud Site". In the "Shell" launched with parameters to access the "Site Cloud" let’s write and run the command: listen passive-cache/name like '%' or a "cohql" query, with your preferred parameters In the "Shell" launched with parameters to access the "Site 1" let’s write and run the following commands: load test/10 load test2/20 delete test/50 Expected result If all is OK, the "Shell" to Site Cloud let us to listen to all the add and delete events within the cache "cache-passive", whose objects satisfy the query condition "name like '%' " (ie, every objects in the cache; you could change the tests and create different queries).Through the Shell to "Site 1" we launched the commands to add and to delete objects on different caches (test and test2). With the "Shell" running on "Site Cloud" we got the evidence (displayed or printed, or in a log file) that its cache has been filled with events and related objects generated by commands executed from the" Shell "on" Site 1 ", thanks to "push-replication" feature. Other tests can be performed, such as, for example, the subscription to the events on the "Site 1" too, using different "cohql" queries, changing the cache configuration, to effectively demonstrate both the potentiality and the versatility produced by these different configurations, even in the cloud, as in our case. More information on how to configure Coherence "Push Replication" can be found in the Oracle Coherence Incubator project documentation at the following link: http://coherence.oracle.com/display/INC10/Home More information on Oracle Coherence "In Memory Data Grid" can be found at the following link: http://www.oracle.com/technetwork/middleware/coherence/overview/index.html To download and execute the whole sources and configurations of the example explained in the above post, click here to download them; After download the last available version of the Push-Replication Pattern library implementation from the Oracle Coherence Incubator site, and download also the related and required version of Oracle Coherence. For simplicity the required .jarS to execute the example (that can be found into the Push-Replication-Pattern download and Coherence Distribution download) are: activemq-core-5.3.1.jar activemq-protobuf-1.0.jar aopalliance-1.0.jar coherence-commandpattern-2.8.4.32329.jar coherence-common-2.2.0.32329.jar coherence-eventdistributionpattern-1.2.0.32329.jar coherence-functorpattern-1.5.4.32329.jar coherence-messagingpattern-2.8.4.32329.jar coherence-processingpattern-1.4.4.32329.jar coherence-pushreplicationpattern-4.0.4.32329.jar coherence-rest.jar coherence.jar commons-logging-1.1.jar commons-logging-api-1.1.jar commons-net-2.0.jar geronimo-j2ee-management_1.0_spec-1.0.jar geronimo-jms_1.1_spec-1.1.1.jar http.jar jackson-all-1.8.1.jar je.jar jersey-core-1.8.jar jersey-json-1.8.jar jersey-server-1.8.jar jl1.0.jar kahadb-5.3.1.jar miglayout-3.6.3.jar org.osgi.core-4.1.0.jar spring-beans-2.5.6.jar spring-context-2.5.6.jar spring-core-2.5.6.jar spring-osgi-core-1.2.1.jar spring-osgi-io-1.2.1.jar At this URL could be found the original article: http://blogs.oracle.com/slc/coherence_into_the_cloud_boost Authors: Nino Guarnacci & Francesco Scarano

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Using Jquery to get JSON objects from local file.

- by ThoughtCrhyme

I'm trying to get a list of JSON objects (products) from a local file using Jquery and store all the objects in a single array called allItems. The file is co-located in the same directory as the code, and it's called "allItems.json". Here's how I'm doing it now: function getAllSupportedItems(){ var allItems = new Array(); $.getJSON("allItems.json", function(data){ $.each(data.items, function(item){ allItems.push(item); }); }); return allItems; } Based on this example: http://api.jquery.com/jQuery.getJSON/

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MongoDB vs. Redis vs. Cassandra for a fast-write, temporary row storage solution

- by Mark Bao

Hi there, I'm building a system that tracks and verifies ad impressions and clicks. This means that there are a lot of insert commands (about 90/second average, peaking at 250) and some read operations, but the focus is on performance and making it blazing-fast. The system is currently on MongoDB, but I've been introduced to Cassandra and Redis since then. Would it be a good idea to go to one of these two solutions, rather than stay on MongoDB? Why or why not? Thank you

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Using wix3 SqlScript to run generated temporary sql-script files.

- by leiflundgren

I am starting to write an installer which will use the SqlScript-element. That takes a reference to the Binary-table what script to run. I would like to dynamically generate the script during the installation. I can see three possibilities: Somehow to get SqlScript to read it data from a file rather then a Binary entry. Inject my generated script into the Binary table Using SqlString Which will cause the need to place some rather long strings into Properties, but I guess that shouldn't really be a prolem. Any advice? Regards Leif (My reason, should anyone be interested is that the database should have a job set up, that calls on an installed exe-file. I prefer to create the job using sqlscript. And the path of that file is not known until InstallDir has been choosen.)

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Can I draw Qt objects directly to Win32 DC (Device Context)?

- by Kevin

I can draw Qt objects to an QImage and then draw the image to HDC or CDC. This may hurt our application's performance. It would be great if I can draw Qt objects directly to Win32 HDC or MFC CDC. I expect that there is a class, say QWin32Image for clear, then I can use it in this way: QWin32Image image(hdc, 100, 100, Format_ARGB32_Premultiplied); QPainter painter(&image); painter.drawText(....); Is it possible for my thought? Or is there a better way to do that?

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When does the .NET runtime hold a reference count > 1 for COM objects?

- by Wim Coenen

Until recently, I believed that the .NET runtime only increases the reference count of COM objects by 1 when creating a runtime-callable wrapper, and that only one such runtime-callable wrapper is created for any given COM object. If I'm not mistaken, the above implies that Marshal.FinalReleaseComObject and Marshal.ReleaseComObject do the same thing in practice. However, today I was writing some tests to verify that COM objects are properly released by my code. I do this by invoking the supposedly released object and checking for the expected InvalidComObjectException. It turns out that there are cases where the exception is thrown after a FinalReleaseComObject, but not after a ReleaseComObject. Does this mean that the .NET 2.0 runtime can hold more than one reference to a COM object? If so, when does it do this?

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How does Linq-to-Xml convert objects to strings?

- by Eamon Nerbonne

Linq-to-Xml contains lots of methods that allow you to add arbitrary objects to an xml tree. These objects are converted to strings by some means, but I can't seem to find the specification of how this occurs. The conversion I'm referring to is mentioned (but not specified) in MSDN. I happen to need this for javascript interop, but that doesn't much matter to the question. Linq to Xml isn't just calling .ToString(). Firstly, it'll accept null elements, and secondly, it's doing things no .ToString() implementation does: For example: new XElement("elem",true).ToString() == "<elem>true</elem>" //but... true.ToString() == "True" //IIRC, this is culture invariant, but in any case... true.ToString(CultureInfo.InvariantCulture) == "True" Other basic data types are similarly specially treated. So, does anybody know what it's doing and where that's described?

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A tool or framework extension or code snippet for logging the internal state of objects?

- by George Mauer

When spiking on how something works or when my unit test behave in an unpredictable manner I usually have to drop into debug mode. 99% of my time in debug mode is spent checking the values of fields on objects to verify its state. I already have log4net set up, it would seem that if I could easily add a line of code to log out the state of objects I could remove most of my need to start up the bulky debugger. The problem is of course that to expose object state implicitly you need to manually override each object's ToString() method. What I would like to be able to do is the ability to do logger.LogState(someObject) and have logged out the object state including at least a formatted list of all the private variables, references (to some arbitrary depth), and collections. Does anyone know a tool/framework/code snippet that can be used to generate a string of the internal state of any object? I could of course write one myself but its a non-trivial problem and I'd prefer something someone has put some thought into.

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Is this way of storing typed objects in memory good?

- by Pindatjuh

This is an "is this okay, or can it be done better" question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical possition when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignement. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 11111111 11111111 11111111 11111111 Data Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 11111111 11111111 11111111 11111111 Is this okay, or can it be done better?

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Is it possible to use objects as function paremeters in EL with JBoss EL resolver?

- by calavera.info

There is this sentence in JBoss EL resolver online documentation: It's important to fully understand how this extension to EL works. When the page is rendered, the parameter names are stored (for example, hotel.id and user.username), and evaluated (as value expressions) when the page is submitted. You can't pass objects as parameters! But I had used objects as function parameters in my project before I accidentally read this hint and it worked! How is it possible? I'm afraid of that there is some magic now...

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How does a Java Arraylist contains() method evalute objects?

- by mvid

Say i create one object and add it to my ArrayList. If I then create another object with exactly the same constructor input, will the contain() method evaluate the two objects to be the same? Assume the constructor doesn't do anything funny with the input, and the variables stored in both objects are identical. ArrayList<Thing> basket = new ArrayList<Thing>(); Thing thing = new Thing(100); basket.add(thing); Thing another = new Thing(100); basket.contains(another); // true or false?

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Where would you document standardized complex data that is passed between many objects and methods?

- by Eli

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Is there a limit on the number of mutex objects that can be created in a Windows process?

- by young-phillip

I'm writing a c# application that can create a series of request messages. Each message could have a response, that needs to be waited on by a consumer. Where the number of outstanding request messages is constrained, I have used the windows EVENT to solve this problem. However, I know there is a limit on how many EVENT objects can be created in a single process, and in this instance, its possible I might exceed that limit. Does anyone know if there is a similar limit on creation of mutex objects or semaphores? I know this can be solved by some sort of pool of shared resources, that are grabbed by consumers when they need to wait, but it would be more convenient if each request message could have its own sync object.

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What ways are there for cleaning an R environment from objects?

- by Tal Galili

I know I can use ls() and rm() to see and remove objects that exist in my environment. However, when dealing with "old" .RData file, one needs to sometimes pick an environment a part to find what to keep and what to leave out. What I would like to do, is to have a GUI like interface to allow me to see the objects, sort them (for example, by there size), and remove the ones I don't need (for example, by a check-box interface). Since I imagine such a system is not currently implemented in R, what ways do exist? What do you use for cleaning old .RData files? Thanks, Tal

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MySQL INSERT data does not get stored in proper db, only temporary?

- by greye

I'm having trouble with MySQL or Python and can't seem to isolate the problem. INSERTs only seem to last the run of the script and are not stored in the database. I have this script: import MySQLdb db = MySQLdb.connect(host="localhost", user="user", passwd="password", db="example") dbcursor = db.cursor() dbcursor.execute("select * from tablename") temp = dbcursor.fetchall() print 'before: '+str(temp) dbcursor.execute('INSERT INTO tablename (data1, data2, data3) VALUES ("1", "a", "b")') dbcursor.execute("select * from tablename") temp = dbcursor.fetchall() print 'after: '+str(temp) The first time I run it I get the expected output: >>> before: () after: ((1L, 'a', 'b'),) The problem is that if I run it again, the before comes out empty when it should already have the entry in it and the after doesn't break (data 1 is primary key). >>> before: () after: ((1L, 'a', 'b'),) >>> before: () after: ((1L, 'a', 'b'),) >>> before: () after: ((1L, 'a', 'b'),) If I try running the insert command twice in the same script it will break ("Duplicate entry for PRIMARY KEY") Any idea what might be happening here?

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How to select all parent objects into DataContext using single LINQ query ?

- by too

I am looking for an answer to a specific problem of fetching whole LINQ object hierarchy using single SELECT. At first I was trying to fill as much LINQ objects as possible using LoadOptions, but AFAIK this method allows only single table to be linked in one query using LoadWith. So I have invented a solution to forcibly set all parent objects of entity which of list is to be fetched, although there is a problem of multiple SELECTS going to database - a single query results in two SELECTS with the same parameters in the same LINQ context. For this question I have simplified this query to popular invoice example: public static class Extensions { public static IEnumerable<T> ForEach<T>(this IEnumerable<T> collection, Action<T> func) { foreach(var c in collection) { func(c); } return collection; } } public IEnumerable<Entry> GetResults(AppDataContext context, int CustomerId) { return ( from entry in context.Entries join invoice in context.Invoices on entry.EntryInvoiceId equals invoice.InvoiceId join period in context.Periods on invoice.InvoicePeriodId equals period.PeriodId // LEFT OUTER JOIN, store is not mandatory join store in context.Stores on entry.EntryStoreId equals store.StoreId into condStore from store in condStore.DefaultIfEmpty() where (invoice.InvoiceCustomerId = CustomerId) orderby entry.EntryPrice descending select new { Entry = entry, Invoice = invoice, Period = period, Store = store } ).ForEach(x => { x.Entry.Invoice = Invoice; x.Invoice.Period = Period; x.Entry.Store = Store; } ).Select(x => x.Entry); } When calling this function and traversing through result set, for example: var entries = GetResults(this.Context); int withoutStore = 0; foreach(var k in entries) { if(k.EntryStoreId == null) withoutStore++; } the resulting query to database looks like (single result is fetched): SELECT [t0].[EntryId], [t0].[EntryInvoiceId], [t0].[EntryStoreId], [t0].[EntryProductId], [t0].[EntryQuantity], [t0].[EntryPrice], [t1].[InvoiceId], [t1].[InvoiceCustomerId], [t1].[InvoiceDate], [t1].[InvoicePeriodId], [t2].[PeriodId], [t2].[PeriodName], [t2].[PeriodDateFrom], [t4].[StoreId], [t4].[StoreName] FROM [Entry] AS [t0] INNER JOIN [Invoice] AS [t1] ON [t0].[EntryInvoiceId] = [t1].[InvoiceId] INNER JOIN [Period] AS [t2] ON [t2].[PeriodId] = [t1].[InvoicePeriodId] LEFT OUTER JOIN ( SELECT 1 AS [test], [t3].[StoreId], [t3].[StoreName] FROM [Store] AS [t3] ) AS [t4] ON [t4].[StoreId] = ([t0].[EntryStoreId]) WHERE (([t1].[InvoiceCustomerId]) = @p0) ORDER BY [t0].[InvoicePrice] DESC -- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [186] -- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 3.5.30729.1 SELECT [t0].[EntryId], [t0].[EntryInvoiceId], [t0].[EntryStoreId], [t0].[EntryProductId], [t0].[EntryQuantity], [t0].[EntryPrice], [t1].[InvoiceId], [t1].[InvoiceCustomerId], [t1].[InvoiceDate], [t1].[InvoicePeriodId], [t2].[PeriodId], [t2].[PeriodName], [t2].[PeriodDateFrom], [t4].[StoreId], [t4].[StoreName] FROM [Entry] AS [t0] INNER JOIN [Invoice] AS [t1] ON [t0].[EntryInvoiceId] = [t1].[InvoiceId] INNER JOIN [Period] AS [t2] ON [t2].[PeriodId] = [t1].[InvoicePeriodId] LEFT OUTER JOIN ( SELECT 1 AS [test], [t3].[StoreId], [t3].[StoreName] FROM [Store] AS [t3] ) AS [t4] ON [t4].[StoreId] = ([t0].[EntryStoreId]) WHERE (([t1].[InvoiceCustomerId]) = @p0) ORDER BY [t0].[InvoicePrice] DESC -- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [186] -- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 3.5.30729.1 The question is why there are two queries and how can I fetch LINQ objects without such hacks?

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