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• Telerik Releases a new Visual Entity Designer

  Love LINQ to SQL but are concerned that it is a second class citizen? Need to connect to more databases other than SQL Server? Think that the Entity Framework is too complex? Want a domain model designer for data access that is easy, yet powerful? Then the Telerik Visual Entity Designer is for you. Built on top of Telerik OpenAccess ORM, a very mature and robust product, Teleriks Visual Entity Designer is a new way to build your domain model that is very powerful and also real easy to use. How easy? Ill show you here. First Look: Using the Telerik Visual Entity Designer To get started, you need to install the Telerik OpenAccess ORM Q1 release for Visual Studio 2008 or 2010. You dont need to use any of the Telerik OpenAccess wizards, designers, or using statements. Just right click on your project and select Add|New Item from the context menu. Choose Telerik OpenAccess Domain Model from the Visual Studio project templates. (Note to existing OpenAccess users, dont run the Enable ORM wizard or any other OpenAccess menu unless you are building OpenAccess Entities.) You will then have to specify the database backend (SQL Server, SQL Azure, Oracle, MySQL, etc) and connection. After you establish your connection, select the database objects you want to add to your domain model. You can also name your model, by default it will be NameofyourdatabaseEntityDiagrams. You can click finish here if you are comfortable, or tweak some advanced settings. Many users of domain models like to add prefixes and suffixes to classes, fields, and properties as well as handle pluralization. I personally accept the defaults, however, I hate how DBAs force underscores on me, so I click on the option to remove them. You can also tweak your namespace, mapping options, and define your own code generation template to gain further control over the outputted code. This is a very powerful feature, but for now, I will just accept the defaults.   When we click finish, you can see your domain model as a file with the .rlinq extension in the Solution Explorer. You can also bring up the visual designer to view or further tweak your model by double clicking on the model in the Solution Explorer.  Time to use the model! Writing a LINQ Query Programming against the domain model is very simple using LINQ. Just set a reference to the model (line 12 of the code below) and write a standard LINQ statement (lines 14-16).  (OpenAccess users: notice the you dont need any using statements for OpenAccess or an IObjectScope, just raw LINQ against your model.) 1: using System; 2: using System.Linq; 3: //no need for anOpenAccess using statement 4:   5: namespace ConsoleApplication3 6: { 7: class Program 8: { 9: static void Main(string[] args) 10: { 11: //a reference tothe data context 12: NorthwindEntityDiagrams dat = new NorthwindEntityDiagrams(); 13: //LINQ Statement 14: var result = from c in dat.Customers 15: where c.Country == "Germany" 16: select c; 17:   18: //Print out the company name 19: foreach (var cust in result) 20: { 21: Console.WriteLine("CompanyName: " + cust.CompanyName); 22: } 23: //keep the consolewindow open 24: Console.Read(); 25: } 26: } 27: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Lines 19-24 loop through the result of our LINQ query and displays the results. Thats it! All of the super powerful features of OpenAccess are available to you to further enhance your experience, however, in most cases this is all you need. In future posts I will show how to use the Visual Designer with some other scenarios. Stay tuned. Enjoy! Technorati Tags: Telerik,OpenAccess,LINQ Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Can a class inherit from LambdaExpression in .NET? Or is this not recommended?

  - by d.

  Consider the following code (C# 4.0): public class Foo : LambdaExpression { } This throws the following design-time error: Foo does not implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) There's absolutely no problem with public class Foo : Expression { } but, out of curiosity and for the sake of learning, I've searched in Google System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) and guess what: zero results returned (when was the last time you saw that?). Needless to say, I haven't found any documentation on this method anywhere else. As I said, one can easily inherit from Expression; on the other hand LambdaExpression, while not marked as sealed (Expression<TDelegate> inherits from it), seems to be designed to prevent inheriting from it. Is this actually the case? Does anyone out there know what this method is about? EDIT (1): More info based on the first answers - If you try to implement Accept, the editor (C# 2010 Express) automatically gives you the following stub: protected override Expression Accept(System.Linq.Expressions.ExpressionVisitor visitor) { return base.Accept(visitor); } But you still get the same error. If you try to use a parameter of type StackSpiller directly, the compiler throws a different error: System.Linq.Expressions.Compiler.StackSpiller is inaccessible due to its protection level. EDIT (2): Based on other answers, inheriting from LambdaExpression is not possible so the question as to whether or not it is recommended becomes irrelevant. I wonder if, in cases like this, the error message should be Foo cannot implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) because [reasons go here]; the current error message (as some answers prove) seems to tell me that all I need to do is implement Accept (which I can't do).

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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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• SSIS - XML Source Script

  - by simonsabin

  The XML Source in SSIS is great if you have a 1 to 1 mapping between entity and table. You can do more complex mapping but it becomes very messy and won't perform. What other options do you have? The challenge with XML processing is to not need a huge amount of memory. I remember using the early versions of Biztalk with loaded the whole document into memory to map from one document type to another. This was fine for small documents but was an absolute killer for large documents. You therefore need a streaming approach. For flexibility however you want to be able to generate your rows easily, and if you've ever used the XmlReader you will know its ugly code to write. That brings me on to LINQ. The is an implementation of LINQ over XML which is really nice. You can write nice LINQ queries instead of the XMLReader stuff. The downside is that by default LINQ to XML requires a whole XML document to work with. No streaming. Your code would look like this. We create an XDocument and then enumerate over a set of annoymous types we generate from our LINQ statement XDocument x = XDocument.Load("C:\\TEMP\\CustomerOrders-Attribute.xml");   foreach (var xdata in (from customer in x.Elements("OrderInterface").Elements("Customer")                        from order in customer.Elements("Orders").Elements("Order")                        select new { Account = customer.Attribute("AccountNumber").Value                                   , OrderDate = order.Attribute("OrderDate").Value }                        )) {     Output0Buffer.AddRow();     Output0Buffer.AccountNumber = xdata.Account;     Output0Buffer.OrderDate = Convert.ToDateTime(xdata.OrderDate); } As I said the downside to this is that you are loading the whole document into memory. I did some googling and came across some helpful videos from a nice UK DPE Mike Taulty http://www.microsoft.com/uk/msdn/screencasts/screencast/289/LINQ-to-XML-Streaming-In-Large-Documents.aspx. Which show you how you can combine LINQ and the XmlReader to get a semi streaming approach. I took what he did and implemented it in SSIS. What I found odd was that when I ran it I got different numbers between using the streamed and non streamed versions. I found the cause was a little bug in Mikes code that causes the pointer in the XmlReader to progress past the start of the element and thus foreach (var xdata in (from customer in StreamReader("C:\\TEMP\\CustomerOrders-Attribute.xml","Customer")                                from order in customer.Elements("Orders").Elements("Order")                                select new { Account = customer.Attribute("AccountNumber").Value                                           , OrderDate = order.Attribute("OrderDate").Value }                                ))         {             Output0Buffer.AddRow();             Output0Buffer.AccountNumber = xdata.Account;             Output0Buffer.OrderDate = Convert.ToDateTime(xdata.OrderDate);         } These look very similiar and they are the key element is the method we are calling, StreamReader. This method is what gives us streaming, what it does is return a enumerable list of elements, because of the way that LINQ works this results in the data being streamed in. static IEnumerable<XElement> StreamReader(String filename, string elementName) {     using (XmlReader xr = XmlReader.Create(filename))     {         xr.MoveToContent();         while (xr.Read()) //Reads the first element         {             while (xr.NodeType == XmlNodeType.Element && xr.Name == elementName)             {                 XElement node = (XElement)XElement.ReadFrom(xr);                   yield return node;             }         }         xr.Close();     } } This code is specifically designed to return a list of the elements with a specific name. The first Read reads the root element and then the inner while loop checks to see if the current element is the type we want. If not we do the xr.Read() again until we find the element type we want. We then use the neat function XElement.ReadFrom to read an element and all its sub elements into an XElement. This is what is returned and can be consumed by the LINQ statement. Essentially once one element has been read we need to check if we are still on the same element type and name (the inner loop) This was Mikes mistake, if we called .Read again we would advance the XmlReader beyond the start of the Element and so the ReadFrom method wouldn't work. So with the code above you can use what ever LINQ statement you like to flatten your XML into the rowsets you want. You could even have multiple outputs and generate your own surrogate keys.        

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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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• 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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• 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

  Hi All, I often find myself with fairly complex data that represents something that my objects will be working on. For example, in a task-list app, several objects might work with an array of tasks, each of which has attributes, temporal expressions, sub tasks and sub sub tasks, etc. One object will collect data from web forms, standardize it into a format consumable by the class that will save them to the database, another object will pull them from the database, put them in the standard format and pass them to the display object, or the update object, etc. The data itself can become a fairly complex series of arrays and sub arrays, representing a 'task' or list of tasks. For example, the below might be one entry in a task list, in the format that is consumable by the various objects that will work on it. Normally, I just document this in a file somewhere with an example. However, I am thinking about the best way to add it to something like PHPDoc, or another standard doc system. Where would you document your consumable data formats that are for many or all of the objects / methods in your app? Array ( [Meta] => Array ( //etc. ) [Sched] => Array ( [SchedID] => 32 [OwnerID] => 2 [StatusID] => 1 [DateFirstTask] => 2011-02-28 [DateLastTask] => [MarginMonths] => 3 ) [TemporalExpressions] => Array ( [0] => Array ( [type] => dw [TemporalExpID] => 3 [ord] => 2 [day] => 6 [month] => 4 ) [1] => Array ( [type] => dm [TemporalExpID] => 32 [day] => 28 [month] => 2 ) ) [Task] => Array ( [SchedTaskID] => 32 [SchedID] => 32 [OwnerID] => 2 [UserID] => 5 [ClientID] => 9 [Title] => Close Prior Year [Body] => [DueTime] => ) [SubTasks] => Array ( [101] => Array ( [SchedSubTaskID] => 101 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Profit and Loss by Class [Body] => [DueDiff] => 0 ) [102] => Array ( [SchedSubTaskID] => 102 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Balance Sheet [Body] => [DueDiff] => 0 ) [103] => Array ( [SchedSubTaskID] => 103 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Current Year for Prior Year Expenses to Accrue [Body] => Look at Journal Entries that are templates as well. [DueDiff] => 0 ) [104] => Array ( [SchedSubTaskID] => 104 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Review Prior Year Membership from 11/1 - 12/31 to Accrue to Current Year [Body] => [DueDiff] => 0 ) [105] => Array ( [SchedSubTaskID] => 105 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Enter Vacation Accrual [Body] => [DueDiff] => 0 ) [106] => Array ( [SchedSubTaskID] => 106 [ParentST] => 105 [RootT] => 32 [UserID] => 2 [Title] => Email Peter requesting Vacation Status of Employees at Year End [Body] => We need Employee Name, Rate and Days of Vacation left to use. We also need to know if the employee used any of the prior year's vacation. [DueDiff] => 43 ) [107] => Array ( [SchedSubTaskID] => 107 [ParentST] => [RootT] => 32 [UserID] => 2 [Title] => Grants Receivable at Year End [Body] => [DueDiff] => 0 ) [108] => Array ( [SchedSubTaskID] => 108 [ParentST] => 107 [RootT] => 32 [UserID] => 2 [Title] => Email Peter Requesting if there were and Grants Receivable at year end [Body] => [DueDiff] => 43 ) ) )

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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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• Can this way of storing typed objects be improved?

  - by Pindatjuh

  This is an "can it be improved"-question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 Windows 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 position 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 alignment. [...] 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 01010101 01010101 01010101 01010101 Data (user defined) Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 01010101 01010101 01010101 01010101 How can I improve this? (Both performance- and memory-consumption wise)

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• How can I send multiple types of objects across Protobuf?

  - by cyclotis04

  I'm implementing a client-server application, and am looking into various ways to serialize and transmit data. I began working with Xml Serializers, which worked rather well, but generate data slowly, and make large objects, especially when they need to be sent over the net. So I started looking into Protobuf, and protobuf-net. My problem lies in the fact that protobuf doesn't sent type information with it. With Xml Serializers, I was able to build a wrapper which would send and receive any various (serializable) object over the same stream, since object serialized into Xml contain the type name of the object. ObjectSocket socket = new ObjectSocket(); socket.AddTypeHandler(typeof(string)); // Tells the socket the types socket.AddTypeHandler(typeof(int)); // of objects we will want socket.AddTypeHandler(typeof(bool)); // to send and receive. socket.AddTypeHandler(typeof(Person)); // When it gets data, it looks for socket.AddTypeHandler(typeof(Address)); // these types in the Xml, then uses // the appropriate serializer. socket.Connect(_host, _port); socket.Send(new Person() { ... }); socket.Send(new Address() { ... }); ... Object o = socket.Read(); Type oType = o.GetType(); if (oType == typeof(Person)) HandlePerson(o as Person); else if (oType == typeof(Address)) HandleAddress(o as Address); ... I've considered a few solutions to this, including creating a master "state" type class, which is the only type of object sent over my socket. This moves away from the functionality I've worked out with Xml Serializers, though, so I'd like to avoid that direction. The second option would be to wrap protobuf objects in some type of wrapper, which defines the type of object. (This wrapper would also include information such as packet ID, and destination.) It seems silly to use protobuf-net to serialize an object, then stick that stream between Xml tags, but I've considered it. Is there an easy way to get this functionality out of protobuf or protobuf-net? I've come up with a third solution, and posted it below, but if you have a better one, please post it too!

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• building objects from xml file at runtime and intializing, in one pass?

  - by KaluSingh Gabbar

  I have to parse the XML file and build objects representation based on that, now once I get all these data I create entries in various database for these data objects. I have to do second pass over that for value as in the first pass all I could do is build the assets in various databases. and in second pass I get the values for all the data and put it in the database. I have a feeling that this can be done in a single pass but I just want to see what are your opinions. As I am just a student who started with professional work, experienced ppl please help. Can someone who have ideas or done similar work, please provide some light on the topic so that I can think over the possibility of the work and get the prototype going based on your suggestion. Thanks a lot for your precious time, I honestly appreciate it.

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• Why should I use mock objects (Java)? Do all mocking frameworks serve the same purpose?

  - by Mehmet Yesin

  I'm preparing a presentation and I need to get a better understanding of what mocking is, what is the purpose of using it, what are the common situations that I should use mock objects? I found out that there are a bunch of mocking frameworks out there. Do they all do the same thing or do I use a specific framework for specific testing purpose? What are the differences between these frameworks? Which one would you recommend for testing Java? here are some stuff that I found: 1.MockingToolkitComparisonMatrix which seems biased. 2.What are mock objects in Java? This is a year old. I thought there might be some better answer today. Thank you.

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• What techniques are available for filtering collections of objects when using zodb?

  - by Omega

  As the title says: What techniques are available for filtering objects when using zodb? The equivalent in SQL terms would be something like filtering results by a date range. Or only returning rows with a particular value set in a column. If I had a series of blog posts and only wanted ones done in the past month, what would I have to do? Is there any way to optimize these kinds of "queries"? My gut tells me iterating over all the objects in a relationship simply to perform a test is less than optimal.

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• How does a Java Arraylist contains() method evaluate 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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• Why I sould not develop an opensource runtime UI Autogeneration from domain objects?

  - by Marco Bettiolo

  I'm using for my projects a rather complete UI auto-generation tool from database entities for windows forms and asp.net I wrote. Now I've built a working prototype UI auto-generation tool from domain objects. Right now it is in early stage of development and by reflection it generates user interface for creating and updating domain objects. I searched a bit and I didn't find other opensource projects that have the same goal. Why? This type of tool is not useful? Is this idea fundamentally flawed? Thanks.

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• How to sort an NSMutableArray of objects by a member of its class, that is an int or float

  - by J. Dave

  I have a class (from NSObject) that contains: NSString name int position float speed I then create an array (NSMutableArray) of objects from this class. I would like to then sort the array by the 'speed' value, which is a float. I initially has the float value as an NSNumber and the int as NSInteger, and I was successfully sorting with: [myMutableArray sortUsingFunction:compareSelector context:@selector(position)]; where myMutableArray is my array of objects. here is the function: static int compareSelector(id p1, id p2, void *context) { SEL methodSelector = (SEL)context; id value1 = [p1 performSelector:methodSelector]; id value2 = [p2 performSelector:methodSelector]; return [value1 compare:value2]; } Now that I am using int instead of NSInteger, the above code does not work. Is there a more low-level command that I should be using to execute the sort? Thank!

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• How to store NSMutableArray of user defined class objects to file system in iphone?

  - by chaitanya

  Can anyone please tell me how to write NSMutableArray of custom class objects to file? below is the code which i am using to write my array "medicationsArray" to file. medicationsArray contains the objects of below medicationData class @interface medicationData: NSObject { NSString *drName; NSString *date; NSString *description; } @end NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES); NSString *documentDir = [path objectAtIndex:0]; NSString *pathWithFileName; NSString *pathWithFileName = [NSString stringWithFormat:@"%@/medicationsArray",documentDir]; [medicationsArray writeToFile:pathWithFileName atomically:NO]; by using this code i am not able to create a file. can anyone help me in this, thanks in advance

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• Entity Framework - Self Tracking Objects - how to reset client side?

  - by David

  I am using wcf with self tracking entity framework objects. On the client side i have bound an entity to an edit form (which has multiple textboxes and comboboxes). After the user hits Save, the entity is sent through wcf to the server wcf service which will attempt to save the entity. If there is a failure (say a network failure), I need to reset the current entity back to original values. How best can I do this client side? (I recognize with Self Tracking objects there is a property OriginalValues however that collection seems to have count=0) so not sure how to get the original values? Thanks-

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