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• ANTS Memory Profiler 7.0

  - by James Michael Hare

  I had always been a fan of ANTS products (Reflector is absolutely invaluable, and their performance profiler is great as well – very easy to use!), so I was curious to see what the ANTS Memory Profiler could show me. Background While a performance profiler will track how much time is typically spent in each unit of code, a memory profiler gives you much more detail on how and where your memory is being consumed and released in a program. As an example, I’d been working on a data access layer at work to call a market data web service.  This web service would take a list of symbols to quote and would return back the quote data.  To help consolidate the thousands of web requests per second we get and reduce load on the web services, we implemented a 5-second cache of quote data.  Not quite long enough to where customers will typically notice a quote go “stale”, but just long enough to be able to collapse multiple quote requests for the same symbol in a short period of time. A 5-second cache may not sound like much, but it actually pays off by saving us roughly 42% of our web service calls, while still providing relatively up-to-date information.  The question is whether or not the extra memory involved in maintaining the cache was worth it, so I decided to fire up the ANTS Memory Profiler and take a look at memory usage. First Impressions The main thing I’ve always loved about the ANTS tools is their ease of use.  Pretty much everything is right there in front of you in a way that makes it easy for you to find what you need with little digging required.  I’ve worked with other, older profilers before (that shall remain nameless other than to hint it was created by a very large chip maker) where it was a mind boggling experience to figure out how to do simple tasks. Not so with AMP.  The opening dialog is very straightforward.  You can choose from here whether to debug an executable, a web application (either in IIS or from VS’s web development server), windows services, etc. So I chose a .NET Executable and navigated to the build location of my test harness.  Then began profiling. At this point while the application is running, you can see a chart of the memory as it ebbs and wanes with allocations and collections.  At any given point in time, you can take snapshots (to compare states) zoom in, or choose to stop at any time.  Snapshots Taking a snapshot also gives you a breakdown of the managed memory heaps for each generation so you get an idea how many objects are staying around for extended periods of time (as an object lives and survives collections, it gets promoted into higher generations where collection becomes less frequent). Generating a snapshot brings up an analysis view with very handy graphs that show your generation sizes.  Almost all my memory is in Generation 1 in the managed memory component of the first graph, which is good news to me, because Gen 2 collections are much rarer.  I once3 made the mistake once of caching data for 30 minutes and found it didn’t get collected very quick after I released my reference because it had been promoted to Gen 2 – doh! Analysis It looks like (from the second pie chart) that the majority of the allocations were in the string class.  This also is expected for me because the majority of the memory allocated is in the web service responses, so it doesn’t seem the entities I’m adapting to (to prevent being too tightly coupled to the web service proxy classes, which can change easily out from under me) aren’t taking a significant portion of memory. I also appreciate that they have clear summary text in key places such as “No issues with large object heap fragmentation were detected”.  For novice users, this type of summary information can be critical to getting them to use a tool and develop a good working knowledge of it. There is also a handy link at the bottom for “What to look for on the summary” which loads a web page of help on key points to look for. Clicking over to the session overview, it’s easy to compare the samples at each snapshot to see how your memory is growing, shrinking, or staying relatively the same.  Looking at my snapshots, I’m pretty happy with the fact that memory allocation and heap size seems to be fairly stable and in control: Once again, you can check on the large object heap, generation one heap, and generation two heap across each snapshot to spot trends. Back on the analysis tab, we can go to the [Class List] button to get an idea what classes are making up the majority of our memory usage.  As was little surprise to me, System.String was the clear majority of my allocations, though I found it surprising that the System.Reflection.RuntimeMehtodInfo came in second.  I was curious about this, so I selected it and went into the [Instance Categorizer].  This view let me see where these instances to RuntimeMehtodInfo were coming from. So I scrolled back through the graph, and discovered that these were being held by the System.ServiceModel.ChannelFactoryRefCache and I was satisfied this was just an artifact of my WCF proxy. I also like that down at the bottom of the Instance Categorizer it gives you a series of filters and offers to guide you on which filter to use based on the problem you are trying to find.  For example, if I suspected a memory leak, I might try to filter for survivors in growing classes.  This means that for instances of a class that are growing in memory (more are being created than cleaned up), which ones are survivors (not collected) from garbage collection.  This might allow me to drill down and find places where I’m holding onto references by mistake and not freeing them! Finally, if you want to really see all your instances and who is holding onto them (preventing collection), you can go to the “Instance Retention Graph” which creates a graph showing what references are being held in memory and who is holding onto them. Visual Studio Integration Of course, VS has its own profiler built in – and for a free bundled profiler it is quite capable – but AMP gives a much cleaner and easier-to-use experience, and when you install it you also get the option of letting it integrate directly into VS. So once you go back into VS after installation, you’ll notice an ANTS menu which lets you launch the ANTS profiler directly from Visual Studio.   Clicking on one of these options fires up the project in the profiler immediately, allowing you to get right in.  It doesn’t integrate with the Visual Studio windows themselves (like the VS profiler does), but still the plethora of information it provides and the clear and concise manner in which it presents it makes it well worth it. Summary If you like the ANTS series of tools, you shouldn’t be disappointed with the ANTS Memory Profiler.  It was so easy to use that I was able to jump in with very little product knowledge and get the information I was looking it for. I’ve used other profilers before that came with 3-inch thick tomes that you had to read in order to get anywhere with the tool, and this one is not like that at all.  It’s built for your everyday developer to get in and find their problems quickly, and I like that! Tweet Technorati Tags: Influencers,ANTS,Memory,Profiler

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• const vs. readonly for a singleton

  - by GlenH7

  First off, I understand there are folk who oppose the use of singletons. I think it's an appropriate use in this case as it's constant state information, but I'm open to differing opinions / solutions. (See The singleton pattern and When should the singleton pattern not be used?) Second, for a broader audience: C++/CLI has a similar keyword to readonly with initonly, so this isn't strictly a C# type question. (Literal field versus constant variable in C++/CLI) Sidenote: A discussion of some of the nuances on using const or readonly. My Question: I have a singleton that anchors together some different data structures. Part of what I expose through that singleton are some lists and other objects, which represent the necessary keys or columns in order to connect the linked data structures. I doubt that anyone would try to change these objects through a different module, but I want to explicitly protect them from that risk. So I'm currently using a "readonly" modifier on those objects*. I'm using readonly instead of const with the lists as I read that using const will embed those items in the referencing assemblies and will therefore trigger a rebuild of those referencing assemblies if / when the list(s) is/are modified. This seems like a tighter coupling than I would want between the modules, but I wonder if I'm obsessing over a moot point. (This is question #2 below) The alternative I see to using "readonly" is to make the variables private and then wrap them with a public get. I'm struggling to see the advantage of this approach as it seems like wrapper code that doesn't provide much additional benefit. (This is question #1 below) It's highly unlikely that we'll change the contents or format of the lists - they're a compilation of things to avoid using magic strings all over the place. Unfortunately, not all the code has converted over to using this singleton's presentation of those strings. Likewise, I don't know that we'd change the containers / classes for the lists. So while I normally argue for the encapsulations advantages a get wrapper provides, I'm just not feeling it in this case. A representative sample of my singleton public sealed class mySingl { private static volatile mySingl sngl; private static object lockObject = new Object(); public readonly Dictionary<string, string> myDict = new Dictionary<string, string>() { {"I", "index"}, {"D", "display"}, }; public enum parms { ABC = 10, DEF = 20, FGH = 30 }; public readonly List<parms> specParms = new List<parms>() { parms.ABC, parms.FGH }; public static mySingl Instance { get { if(sngl == null) { lock(lockObject) { if(sngl == null) sngl = new mySingl(); } } return sngl; } } private mySingl() { doSomething(); } } Questions: Am I taking the most reasonable approach in this case? Should I be worrying about const vs. readonly? is there a better way of providing this information?

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• Poner aplicaci&oacute;n Asp.Net en modo OFFLINE

  - by Jason Ulloa

  Una de las opciones que todo aplicación debería tener es el poder ponerse en modo OFFLINE para evitar el acceso de usuarios. Esto es completamente necesario cuando queremos realizar cambios a nuestra aplicación (cambiar algo, poner una actualización, etc) o a nuestra base de datos y evitarnos problemas con los usuarios que se encuentren logueados dentro de la aplicación en ese momento. Muchos ejemplos a través de la Web exponen la forma de realizar esta tarea utilizando dos técnicas: 1. La primera de ellas es utilizar el archivo App_Offline.htm sin embargo, esta técnica tiene un inconveniente. Y es que, una vez que hemos subido el archivo a nuestra aplicación esta se bloquea completamente y no tenemos forma de volver a ponerla ONLINE a menos que eliminemos el archivo. Es decir no podemos controlarla. 2. La segunda de ellas es el utilizar la etiqueta httpRuntime, pero nuevamente tenemos el mismo problema. Al habilitar el modo OFFLINE mediante esta etiqueta, tampoco podremos acceder a un modo de administración para cambiarla. Un ejemplo de la etiqueta httpRuntime <configuration> <system.web> <httpRuntime enable="false" /> </system.web> </configuration>   Tomando en cuenta lo anterior, lo mas optimo seria que podamos por medio de alguna pagina de administración colocar nuestro sitio en modo OFFLINE, pero manteniendo el acceso a la pagina de administración para poder volver a cambiar el valor que pondrá nuestra aplicación nuevamente en modo ONLINE. Para ello, utilizaremos el web.config de nuestra aplicación y una pequeña clase que se encargara de Leer y escribir los valores. Lo primero será, abrir nuestro web.config y definir dentro del appSettings dos nuevas KEY que contendrán los valores para el modo OFFLINE de nuestra aplicación: <appSettings> <add key="IsOffline" value="false" /> <add key="IsOfflineMessage" value="Sistema temporalmente no disponible por tareas de mantenimiento." /> </appSettings>   En las KEY anteriores tenemos el IsOffLine con value de false, esto es para indicarle a nuestra aplicación que actualmente su modo de funcionamiento es ONLINE, este valor será el que posteriormente cambiemos a TRUE para volver al modo OFFLINE. Nuestra segunda KEY (IsOfflineMessage) posee el value (Sistema temporalmente….) que será mostrado al usuario como un mensaje cuando el sitio este en modo OFFLINE. Una vez definidas nuestras dos KEY en el web.config, escribiremos una clase personalizada para leer y escribir los valores. Así que, agregamos un nuevo elemento de tipo clase al proyecto llamado SettingsRules y la definimos como Public. Está clase contendrá dos métodos, el primero será para leer los valores: public string readIsOnlineSettings(string sectionToRead) { Configuration cfg = WebConfigurationManager.OpenWebConfiguration(System.Web.Hosting.HostingEnvironment.ApplicationVirtualPath); KeyValueConfigurationElement isOnlineSettings = (KeyValueConfigurationElement)cfg.AppSettings.Settings[sectionToRead]; return isOnlineSettings.Value; }   El segundo método, será el encargado de escribir los nuevos valores al web.config public bool saveIsOnlineSettings(string sectionToWrite, string value) { bool succesFullySaved;   try { Configuration cfg = WebConfigurationManager.OpenWebConfiguration(System.Web.Hosting.HostingEnvironment.ApplicationVirtualPath); KeyValueConfigurationElement repositorySettings = (KeyValueConfigurationElement)cfg.AppSettings.Settings[sectionToWrite];   if (repositorySettings != null) { repositorySettings.Value = value; cfg.Save(ConfigurationSaveMode.Modified); } succesFullySaved = true; } catch (Exception) { succesFullySaved = false; } return succesFullySaved; }   Por último, definiremos en nuestra clase una región llamada instance, que contendrá un método encargado de devolver una instancia de la clase (esto para no tener que hacerlo luego) #region instance   private static SettingsRules m_instance;   // Properties public static SettingsRules Instance { get { if (m_instance == null) { m_instance = new SettingsRules(); } return m_instance; } }   #endregion instance   Con esto, nuestra clase principal esta completa. Así que pasaremos a la implementación de las páginas y el resto de código que completará la funcionalidad.   Para complementar la tarea del web.config utilizaremos el fabuloso GLOBAL.ASAX, este contendrá el código encargado de detectar si nuestra aplicación tiene el valor de ONLINE o OFFLINE y además de bloquear todas las paginas y directorios excepto el que le hayamos definido como administrador, esto para luego poder volver a configurar el sitio.   El evento del Global.Asax que utilizaremos será el Application_BeginRequest   protected void Application_BeginRequest(Object sender, EventArgs e) {   if (Convert.ToBoolean(SettingsRules.Instance.readIsOnlineSettings("IsOffline"))) {   string Virtual = Request.Path.Substring(0, Request.Path.LastIndexOf("/") + 1);   if (Virtual.ToLower().IndexOf("/admin/") == -1) { //We don't makes action, is admin section Server.Transfer("~/TemporarilyOfflineMessage.aspx"); }   } } La primer Línea del IF, verifica si el atributo del web.config es True o False, si es true toma la dirección WEB que se ha solicitado y la incluimos en un IF para verificar si corresponde a la Sección admin (está sección no es mas que un folder en nuestra aplicación llamado admin y puede ser cambiado a cualquier otro). Si el resultado de ese if es –1 quiere decir que no coincide, entonces, esa será la bandera que nos permitirá bloquear inmediatamente la pagina actual, transfiriendo al usuario a una pagina de mantenimiento. Ahora, en nuestra carpeta Admin crearemos una nueva pagina asp.net llamada OnlineSettings.aspx para actualizar y leer los datos del web.config y una pagina Default.aspx para pruebas. Nuestra página OnlineSettings tendrá dos pasos importantes: 1. Leer los datos actuales de configuración protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { IsOffline.Checked = Convert.ToBoolean(mySettings.readIsOnlineSettings("IsOffline")); OfflineMessage.Text = mySettings.readIsOnlineSettings("IsOfflineMessage"); } }   2. Actualizar los datos con los nuevos valores. protected void UpdateButton_Click(object sender, EventArgs e) { string htmlMessage = OfflineMessage.Text.Replace(Environment.NewLine, "<br />");   // Update the Application variables Application.Lock(); if (IsOffline.Checked) { mySettings.saveIsOnlineSettings("IsOffline", "True"); mySettings.saveIsOnlineSettings("IsOfflineMessage", htmlMessage); } else { mySettings.saveIsOnlineSettings("IsOffline", "false"); mySettings.saveIsOnlineSettings("IsOfflineMessage", htmlMessage); }   Application.UnLock(); }   Por último en la raíz de la aplicación, crearemos una nueva página aspx llamada TemporarilyOfflineMessage.aspx que será la que se muestre cuando se bloquee la aplicación. Al final nuestra aplicación se vería algo así Página bloqueada Configuración del Bloqueo Y para terminar la aplicación de ejemplo

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• Sniffing out SQL Code Smells: Inconsistent use of Symbolic names and Datatypes

  - by Phil Factor

  It is an awkward feeling. You’ve just delivered a database application that seems to be working fine in production, and you just run a few checks on it. You discover that there is a potential bug that, out of sheer good chance, hasn’t kicked in to produce an error; but it lurks, like a smoking bomb. Worse, maybe you find that the bug has started its evil work of corrupting the data, but in ways that nobody has, so far detected. You investigate, and find the damage. You are somehow going to have to repair it. Yes, it still very occasionally happens to me. It is not a nice feeling, and I do anything I can to prevent it happening. That’s why I’m interested in SQL code smells. SQL Code Smells aren’t necessarily bad practices, but just show you where to focus your attention when checking an application. Sometimes with databases the bugs can be subtle. SQL is rather like HTML: the language does its best to try to carry out your wishes, rather than to be picky about your bugs. Most of the time, this is a great benefit, but not always. One particular place where this can be detrimental is where you have implicit conversion between different data types. Most of the time it is completely harmless but we’re  concerned about the occasional time it isn’t. Let’s give an example: String truncation. Let’s give another even more frightening one, rounding errors on assignment to a number of different precision. Each requires a blog-post to explain in detail and I’m not now going to try. Just remember that it is not always a good idea to assign data to variables, parameters or even columns when they aren’t the same datatype, especially if you are relying on implicit conversion to work its magic.For details of the problem and the consequences, see here:  SR0014: Data loss might occur when casting from {Type1} to {Type2} . For any experienced Database Developer, this is a more frightening read than a Vampire Story. This is why one of the SQL Code Smells that makes me edgy, in my own or other peoples’ code, is to see parameters, variables and columns that have the same names and different datatypes. Whereas quite a lot of this is perfectly normal and natural, you need to check in case one of two things have gone wrong. Either sloppy naming, or mixed datatypes. Sure it is hard to remember whether you decided that the length of a log entry was 80 or 100 characters long, or the precision of a number. That is why a little check like this I’m going to show you is excellent for tidying up your code before you check it back into source Control! 1/ Checking Parameters only If you were just going to check parameters, you might just do this. It simply groups all the parameters, either input or output, of all the routines (e.g. stored procedures or functions) by their name and checks to see, in the HAVING clause, whether their data types are all the same. If not, it lists all the examples and their origin (the routine) Even this little check can occasionally be scarily revealing. ;WITH userParameter AS  ( SELECT   c.NAME AS ParameterName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  t.name + ' '     + CASE     --we may have to put in the length            WHEN t.name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.max_length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.name IN ('nchar', 'nvarchar')                      THEN c.max_length / 2 ELSE c.max_length                    END)                END + ')'         WHEN t.name IN ('decimal', 'numeric')             THEN '(' + CONVERT(VARCHAR(4), c.precision)                   + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = c.XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType]  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'   AND parameter_id>0)SELECT CONVERT(CHAR(80),objectName+'.'+ParameterName),DataType FROM UserParameterWHERE ParameterName IN   (SELECT ParameterName FROM UserParameter    GROUP BY ParameterName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY ParameterName   so, in a very small example here, we have a @ClosingDelimiter variable that is only CHAR(1) when, by the looks of it, it should be up to ten characters long, or even worse, a function that should be a char(1) and seems to let in a string of ten characters. Worth investigating. Then we have a @Comment variable that can't decide whether it is a VARCHAR(2000) or a VARCHAR(MAX) 2/ Columns and Parameters Actually, once we’ve cleared up the mess we’ve made of our parameter-naming in the database we’re inspecting, we’re going to be more interested in listing both columns and parameters. We can do this by modifying the routine to list columns as well as parameters. Because of the slight complexity of creating the string version of the datatypes, we will create a fake table of both columns and parameters so that they can both be processed the same way. After all, we want the datatypes to match Unfortunately, parameters do not expose all the attributes we are interested in, such as whether they are nullable (oh yes, subtle bugs happen if this isn’t consistent for a datatype). We’ll have to leave them out for this check. Voila! A slight modification of the first routine ;WITH userObject AS  ( SELECT   Name AS DataName,--the actual name of the parameter or column ('@' removed)  --and the qualified object name of the routine  OBJECT_SCHEMA_NAME(ObjectID) + '.' + OBJECT_NAME(ObjectID) AS ObjectName,  --now the harder bit: the definition of the datatype.  TypeName + ' '     + CASE     --we may have to put in the length. e.g. CHAR (10)           WHEN TypeName IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN MaxLength = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN TypeName IN ('nchar', 'nvarchar')                      THEN MaxLength / 2 ELSE MaxLength                    END)                END + ')'         WHEN TypeName IN ('decimal', 'numeric')--a BCD number!             THEN '(' + CONVERT(VARCHAR(4), Precision)                   + ',' + CONVERT(VARCHAR(4), Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0 --tush tush. XML         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT TOP 1 QUOTENAME(ss.name) + '.' + QUOTENAME(sc.Name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType],       DataObjectType  FROM   (Select t.name AS TypeName, REPLACE(c.name,'@','') AS Name,          c.max_length AS MaxLength, c.precision AS [Precision],           c.scale AS [Scale], c.[Object_id] AS ObjectID, XML_collection_ID,          is_XML_Document,'P' AS DataobjectType  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  AND parameter_id>0  UNION all  Select t.name AS TypeName, c.name AS Name, c.max_length AS MaxLength,          c.precision AS [Precision], c.scale AS [Scale],          c.[Object_id] AS ObjectID, XML_collection_ID,is_XML_Document,          'C' AS DataobjectType            FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID   WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'  )f)SELECT CONVERT(CHAR(80),objectName+'.'   + CASE WHEN DataobjectType ='P' THEN '@' ELSE '' END + DataName),DataType FROM UserObjectWHERE DataName IN   (SELECT DataName FROM UserObject   GROUP BY DataName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY DataName     Hmm. I can tell you I found quite a few minor issues with the various tabases I tested this on, and found some potential bugs that really leap out at you from the results. Here is the start of the result for AdventureWorks. Yes, AccountNumber is, for some reason, a Varchar(10) in the Customer table. Hmm. odd. Why is a city fifty characters long in that view?  The idea of the description of a colour being 256 characters long seems over-ambitious. Go down the list and you'll spot other mistakes. There are no bugs, but just mess. We started out with a listing to examine parameters, then we mixed parameters and columns. Our last listing is for a slightly more in-depth look at table columns. You’ll notice that we’ve delibarately removed the indication of whether a column is persisted, or is an identity column because that gives us false positives for our code smells. If you just want to browse your metadata for other reasons (and it can quite help in some circumstances) then uncomment them! ;WITH userColumns AS  ( SELECT   c.NAME AS columnName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  REPLACE(t.name + ' '   + CASE WHEN is_computed = 1 THEN ' AS ' + --do DDL for a computed column          (SELECT definition FROM sys.computed_columns cc           WHERE cc.object_id = c.object_id AND cc.column_ID = c.column_ID)     --we may have to put in the length            WHEN t.Name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.Max_Length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.Name IN ('nchar', 'nvarchar')                      THEN c.Max_Length / 2 ELSE c.Max_Length                    END)                END + ')'       WHEN t.name IN ('decimal', 'numeric')       THEN '(' + CONVERT(VARCHAR(4), c.precision) + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'       ELSE ''      END + CASE WHEN c.is_rowguidcol = 1          THEN ' ROWGUIDCOL'          ELSE ''         END + CASE WHEN XML_collection_ID <> 0            THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                THEN 'DOCUMENT '                ELSE 'CONTENT '               END + COALESCE((SELECT                QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM                sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE                sc.xml_collection_ID = c.XML_collection_ID),                'NULL') + ')'            ELSE ''           END + CASE WHEN is_identity = 1             THEN CASE WHEN OBJECTPROPERTY(object_id,                'IsUserTable') = 1 AND COLUMNPROPERTY(object_id,                c.name,                'IsIDNotForRepl') = 0 AND OBJECTPROPERTY(object_id,                'IsMSShipped') = 0                THEN ''                ELSE ' NOT FOR REPLICATION '               END             ELSE ''            END + CASE WHEN c.is_nullable = 0               THEN ' NOT NULL'               ELSE ' NULL'              END + CASE                WHEN c.default_object_id <> 0                THEN ' DEFAULT ' + object_Definition(c.default_object_id)                ELSE ''               END + CASE                WHEN c.collation_name IS NULL                THEN ''                WHEN c.collation_name <> (SELECT                collation_name                FROM                sys.databases                WHERE                name = DB_NAME()) COLLATE Latin1_General_CI_AS                THEN COALESCE(' COLLATE ' + c.collation_name,                '')                ELSE ''                END,'  ',' ') AS [DataType]FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys')SELECT CONVERT(CHAR(80),objectName+'.'+columnName),DataType FROM UserColumnsWHERE columnName IN (SELECT columnName FROM UserColumns  GROUP BY columnName  HAVING MIN(Datatype)<>MAX(DataType))ORDER BY columnName If you take a look down the results against Adventureworks, you'll see once again that there are things to investigate, mostly, in the illustration, discrepancies between null and non-null datatypes So I here you ask, what about temporary variables within routines? If ever there was a source of elusive bugs, you'll find it there. Sadly, these temporary variables are not stored in the metadata so we'll have to find a more subtle way of flushing these out, and that will, I'm afraid, have to wait!

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• Custom Lookup Provider For NetBeans Platform CRUD Tutorial

  - by Geertjan

  For a long time I've been planning to rewrite the second part of the NetBeans Platform CRUD Application Tutorial to integrate the loosely coupled capabilities introduced in a seperate series of articles based on articles by Antonio Vieiro (a great series, by the way). Nothing like getting into the Lookup stuff right from the get go (rather than as an afterthought)! The question, of course, is how to integrate the loosely coupled capabilities in a logical way within that tutorial. Today I worked through the tutorial from scratch, up until the point where the prototype is completed, i.e., there's a JTextArea displaying data pulled from a database. That brought me to the place where I needed to be. In fact, as soon as the prototype is completed, i.e., the database connection has been shown to work, the whole story about Lookup.Provider and InstanceContent should be introduced, so that all the subsequent sections, i.e., everything within "Integrating CRUD Functionality" will be done by adding new capabilities to the Lookup.Provider. However, before I perform open heart surgery on that tutorial, I'd like to run the scenario by all those reading this blog who understand what I'm trying to do! (I.e., probably anyone who has read this far into this blog entry.) So, this is what I propose should happen and in this order: Point out the fact that right now the database access code is found directly within our TopComponent. Not good. Because you're mixing view code with data code and, ideally, the developers creating the user interface wouldn't need to know anything about the data access layer. Better to separate out the data access code into a separate class, within the CustomerLibrary module, i.e., far away from the module providing the user interface, with this content: public class CustomerDataAccess { public List<Customer> getAllCustomers() { return Persistence.createEntityManagerFactory("CustomerLibraryPU"). createEntityManager().createNamedQuery("Customer.findAll").getResultList(); } } Point out the fact that there is a concept of "Lookup" (which readers of the tutorial should know about since they should have followed the NetBeans Platform Quick Start), which is a registry into which objects can be published and to which other objects can be listening. In the same way as a TopComponent provides a Lookup, as demonstrated in the NetBeans Platform Quick Start, your own object can also provide a Lookup. So, therefore, let's provide a Lookup for Customer objects.  import org.openide.util.Lookup; import org.openide.util.lookup.AbstractLookup; import org.openide.util.lookup.InstanceContent; public class CustomerLookupProvider implements Lookup.Provider { private Lookup lookup; private InstanceContent instanceContent; public CustomerLookupProvider() { // Create an InstanceContent to hold capabilities... instanceContent = new InstanceContent(); // Create an AbstractLookup to expose the InstanceContent... lookup = new AbstractLookup(instanceContent); // Add a "Read" capability to the Lookup of the provider: //...to come... // Add a "Update" capability to the Lookup of the provider: //...to come... // Add a "Create" capability to the Lookup of the provider: //...to come... // Add a "Delete" capability to the Lookup of the provider: //...to come... } @Override public Lookup getLookup() { return lookup; } } Point out the fact that, in the same way as we can publish an object into the Lookup of a TopComponent, we can now also publish an object into the Lookup of our CustomerLookupProvider. Instead of publishing a String, as in the NetBeans Platform Quick Start, we'll publish an instance of our own type. And here is the type: public interface ReadCapability { public void read() throws Exception; } And here is an implementation of our type added to our Lookup: public class CustomerLookupProvider implements Lookup.Provider { private Set<Customer> customerSet; private Lookup lookup; private InstanceContent instanceContent; public CustomerLookupProvider() { customerSet = new HashSet<Customer>(); // Create an InstanceContent to hold capabilities... instanceContent = new InstanceContent(); // Create an AbstractLookup to expose the InstanceContent... lookup = new AbstractLookup(instanceContent); // Add a "Read" capability to the Lookup of the provider: instanceContent.add(new ReadCapability() { @Override public void read() throws Exception { ProgressHandle handle = ProgressHandleFactory.createHandle("Loading..."); handle.start(); customerSet.addAll(new CustomerDataAccess().getAllCustomers()); handle.finish(); } }); // Add a "Update" capability to the Lookup of the provider: //...to come... // Add a "Create" capability to the Lookup of the provider: //...to come... // Add a "Delete" capability to the Lookup of the provider: //...to come... } @Override public Lookup getLookup() { return lookup; } public Set<Customer> getCustomers() { return customerSet; } } Point out that we can now create a new instance of our Lookup (in some other module, so long as it has a dependency on the module providing the CustomerLookupProvider and the ReadCapability), retrieve the ReadCapability, and then do something with the customers that are returned, here in the rewritten constructor of the TopComponent, without needing to know anything about how the database access is actually achieved since that is hidden in the implementation of our type, above: public CustomerViewerTopComponent() { initComponents(); setName(Bundle.CTL_CustomerViewerTopComponent()); setToolTipText(Bundle.HINT_CustomerViewerTopComponent()); // EntityManager entityManager = Persistence.createEntityManagerFactory("CustomerLibraryPU").createEntityManager(); // Query query = entityManager.createNamedQuery("Customer.findAll"); // List<Customer> resultList = query.getResultList(); // for (Customer c : resultList) { // jTextArea1.append(c.getName() + " (" + c.getCity() + ")" + "\n"); // } CustomerLookupProvider lookup = new CustomerLookupProvider(); ReadCapability rc = lookup.getLookup().lookup(ReadCapability.class); try { rc.read(); for (Customer c : lookup.getCustomers()) { jTextArea1.append(c.getName() + " (" + c.getCity() + ")" + "\n"); } } catch (Exception ex) { Exceptions.printStackTrace(ex); } } Does the above make as much sense to others as it does to me, including the naming of the classes? Feedback would be appreciated! Then I'll integrate into the tutorial and do the same for the other sections, i.e., "Create", "Update", and "Delete". (By the way, of course, the tutorial ends up showing that, rather than using a JTextArea to display data, you can use Nodes and explorer views to do so.)

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• Creating a two-way Forest trust with Powershell

  - by Michel Klomp

  Here is a small Powershell script for creating a two-way forest trust. $localforest = [System.DirectoryServices.ActiveDirectory.Forest]::getCurrentForest() $strRemoteForest = ‘domain.local’ $strRemoteUser = ‘administrator’ $strRemotePassword = ‘P@ssw0rd’ $remoteContext = New-Object System.DirectoryServices.ActiveDirectory.DirectoryContext(‘Forest’, $strRemoteForest,$strRemoteUser,$strRemotePassword) $remoteForest = [System.DirectoryServices.ActiveDirectory.Forest]::getForest($remoteContext) $localForest.CreateTrustRelationship($remoteForest,’Bidirectional’)

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• Custom shadow mapping in Unity 3D Free Edition

  - by nosferat

  Since real time hard and soft shadows are Unity 3D Pro only features I thought I will learn Cg programming and create my own shadow mapping shader. But after some digging I found that the shadow mapping technique uses depth textures, and in Unity depth values can be accessed through a Render Texture object, which is Unity Pro only again. So is it true, that I cannot create real time shadow shaders as a workaround to the limitations of the free version?

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• Ensure your view and function meta data is upto date.

  - by simonsabin

  You will see if you use views and functions that SQL Server holds the rowset metadata for this in system tables. This means that if you change the underlying tables, columns and data types your views and functions can be out of sync. This is especially the case with views and functions that use select * To get the metadata to be updated you need to use sp_refreshsqlmodule. This forces the object to be “re run” into the database and the meta data updated. Thomas mentioned sp_refreshview which is a...(read more)

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• PostSharp, Obfuscation, and IL

  - by Simon Cooper

  Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

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• Merge Records in Session bean by using ADF Drag/Drop

  - by shantala.sankeshwar

  This article describes how to merge multiple selected records in Session Bean using ADF drag & drop feature. Below described is simple use case that shows how exactly this can be achieved. Here we will have table & user input field.Table shows  EMP records & user input field accepts Salary.When we drag & drop multiple records on user input field,the selected records get updated with the new Salary provided. Steps: Let us suppose that we have created Java EE Web Application with Entities from Emp table.Then create EJB Session Bean & generate Data control for the same. Write a simple code in sessionEJBBean & expose this method to local interface :  public void updateEmprecords(List empList, Object sal) {       Emp emp = null;       for (int i = 0; i < empList.size(); i++)       {        emp = em.find(Emp.class, empList.get(i));         emp.setSal((BigDecimal)sal);       }      em.merge(emp);   } Now let us create updateEmpRecords.jspx page in viewController project & Drop empFindAll object as ADF Table Define custom SelectionListener method for the table :   public void selectionListener(SelectionEvent selectionEvent)     {     // This method gets the Empno of the selected record & stores in the list object      UIXTable table = (UIXTable)selectionEvent.getComponent();      FacesCtrlHierNodeBinding fcr      =(FacesCtrlHierNodeBinding)table.getSelectedRowData();      Number empNo = (Number)fcr.getAttribute("empno") ;      this.getSelectedRowsList().add(empNo);     }Set table's selectedRowKeys to #{bindings.empFindAll.collectionModel.selectedRow}"Drop inputText on the same jspx page that accepts Salary .Now we would like to drag records from the above table & drop that on the inputtext field.This feature can be achieved by inserting dragSource operation inside the table & dropTraget operation inside the inputText:<af:dragSource discriminant="tab"/> //Insert this inside the table<af:inputText label="Enter Salary" id="it13" autoSubmit="true"       binding="# {test.deptValue}">       <af:dropTarget dropListener="#{test.handleTableDrop}">       <af:dataFlavor        flavorClass="org.apache.myfaces.trinidad.model.RowKeySet"    discriminant="tab"/>       </af:dropTarget>       <af:convertNumber/> </af:inputText> In the above code when the user drags & drops multiple records on inputText,the dropListener method gets called.Goto the respective page definition file & create updateEmprecords method action& execute action dropListener method code:        public DnDAction handleTableDrop(DropEvent dropEvent)        {          //Below code gets the updateEmprecords method,passes parameters & executes method            DataFlavor<RowKeySet> df = DataFlavor.getDataFlavor(RowKeySet.class);            RowKeySet droppedKeySet = dropEvent.getTransferable().getData(df);            if (droppedKeySet != null && droppedKeySet.size() > 0)           {                  DCBindingContainer bindings =                  (DCBindingContainer)BindingContext.getCurrent().getCurrentBindingsEntry();                  OperationBinding updateEmp;                  updateEmp= bindings.getOperationBinding("updateEmprecords");                  updateEmp.getParamsMap().put("sal",                  this.getDeptValue().getAttributes().get("value"));                            updateEmp.getParamsMap().put("empList", this.getSelectedRowsList());                  updateEmp.execute(); //Below code performs execute operation to refresh the updated records                 OperationBinding executeBinding;                 executeBinding= bindings.getOperationBinding("Execute");                 executeBinding.execute(); AdfFacesContext.getCurrentInstance().addPartialTarget(dropEvent.getDragComponent());                this.getSelectedRowsList().clear();          }                 return DnDAction.NONE;        }Run updateEmpRecords.jspx page & enter any Salary say '5000'.Select multiple records in table & drop these selected records on the inputText Salary. Note that all the selected records salary value gets updated to 5000.Technorati Tags: ADF Drag and drop,EJB Session bean,ADF table,inputText,DropEvent  

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• 2D game editor with SDK or open format (Windows)

  - by Edward83

  I need 2d editor (Windows) for game like rpg. Mostly important features for me: Load tiles as classes with attributes, for example "tile1 with coordinates [25,30] is object of class FlyingMonster with speed=1.0f"; Export map to my own format (SDK) or open format which I can convert to my own; As good extension feature will be multi-tile brush. I wanna to choose one or many tiles into one brush and spread it on canvas.

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• Unity: Spin wheels to move vehicle

  - by Paul Manta

  I am just getting started with Unity and I'd like to ask a question. If I have a "Vehicle" object that has two children: "FrontWheel" and "BackWheel" (both 'wheels' are cylinders), how should I set everything up such that I can move the entire vehicle by turning its wheels? When I apply a torque to "FrontWheel", the vehicle starts to move, but instead of the whole thing the moving together, the chassis is rolling on the cylinders and eventually falls off. How can I prevent it from doing that?

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• ASP.NET Hosting :: ASP.NET File Upload Control

  - by mbridge

  The asp.net FileUpload control allows a user to browse and upload files to the web server. From developers perspective, it is as simple as dragging and dropping the FileUpload control to the aspx page. An extra control, like a Button control, or some other control is needed, to actually save the file. <asp:FileUploadID="FileUpload1"runat="server"/> <asp:ButtonID="B1"runat="server"Text="Save"OnClick="B1_Click"/> By default, the FileUpload control allows a maximum of 4MB file to be uploaded and the execution timeout is 110 seconds. These properties can be changed from within the web.config file’s httpRuntime section. The maxRequestLength property determines the maximum file size that can be uploaded. The executionTimeout property determines the maximum time for execution. <httpRuntimemaxRequestLength="8192"executionTimeout="220"/> From code behind, the mime type, size of the file, file name and the extension of the file can be obtained. The maximum file size that can be uploaded can be obtained and modified using the System.Web.Configuration.HttpRuntimeSection class. Files can be alternatively saved using the System.IO.HttpFileCollection class. This collection class can be populated using the Request.Files property. The collection contains HttpPostedFile class which contains a reference to the class. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.IO; using System.Configuration; using System.Web.Configuration;   namespace WebApplication1 {     public partial class WebControls : System.Web.UI.Page     {         protected void Page_Load(object sender, EventArgs e)         {         }           //Using FileUpload control to upload and save files         protected void B1_Click(object sender, EventArgs e)         {             if (FileUpload1.HasFile && FileUpload1.PostedFile.ContentLength > 0)             {                 //mime type of the uploaded file                 string mimeType = FileUpload1.PostedFile.ContentType;                   //size of the uploaded file                 int size = FileUpload1.PostedFile.ContentLength; // bytes                   //extension of the uploaded file                 string extension = System.IO.Path.GetExtension(FileUpload1.FileName);                                  //save file                 string path = Server.MapPath("path");                                 FileUpload1.SaveAs(path + FileUpload1.FileName);                              }             //maximum file size allowed             HttpRuntimeSection rt = new HttpRuntimeSection();             rt.MaxRequestLength = rt.MaxRequestLength * 2;             int length = rt.MaxRequestLength;                     //execution timeout             TimeSpan ts = rt.ExecutionTimeout;             double secomds = ts.TotalSeconds;           }           //Using Request.Files to save files         private void AltSaveFile()         {             HttpFileCollection coll = Request.Files;             for (int i = 0; i < coll.Count; i++)             {                 HttpPostedFile file = coll[i];                   if (file.ContentLength > 0)                     ;//do something             }         }     } }

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• Titan – The Mystery of the Missing Waves

  - by Akemi Iwaya

  The moon Titan holds a unique distinction…it is the only other known ‘object’ in our solar system with a dense atmosphere and stable bodies of surface liquid. Unlike Earth though, there are no waves on Titan. This mystery has planetary scientists baffled and on a quest to understand this incredible phenomenon. Titan: The Mystery of the Missing Waves [YouTube]     

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• Class Design -- Multiple Calls from One Method or One Call from Multiple Methods?

  - by Andrew

  I've been working on some code recently that interfaces with a CMS we use and it's presented me with a question on class design that I think is applicable in a number of situations. Essentially, what I am doing is extracting information from the CMS and transforming this information into objects that I can use programatically for other purposes. This consists of two steps: Retrieve the data from the CMS (we have a DAL that I use, so this is essentially just specifying what data from the CMS I want--no connection logic or anything like that) Map the parsed data to my own [C#] objects There are basically two ways I can approach this: One call from multiple methods public void MainMethodWhereIDoStuff() { IEnumerable<MyObject> myObjects = GetMyObjects(); // Do other stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); List<MyObject> mappedObjects = new List<MyObject>(); // do stuff to map the CmsDataItems to MyObjects return mappedObjects; } private static IEnumerable<CmsDataItem> GetCmsDataItems() { List<CmsDataItem> cmsDataItems = new List<CmsDataItem>(); // do stuff to get the CmsDataItems I want return cmsDataItems; } Multiple calls from one method public void MainMethodWhereIDoStuff() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); IEnumerable<MyObject> myObjects = GetMyObjects(cmsDataItems); // do stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects(IEnumerable<CmsDataItem> itemsToMap) { // ... } private static IEnumerable<CmsDataItem> GetCmsDataItems() { // ... } I am tempted to say that the latter is better than the former, as GetMyObjects does not depend on GetCmsDataItems, and it is explicit in the calling method the steps that are executed to retrieve the objects (I'm concerned that the first approach is kind of an object-oriented version of spaghetti code). On the other hand, the two helper methods are never going to be used outside of the class, so I'm not sure if it really matters whether one depends on the other. Furthermore, I like the fact that in the first approach the objects can be retrieved from one line-- most likely anyone working with the main method doesn't care how the objects are retrieved, they just need to retrieve the objects, and the "daisy chained" helper methods hide the exact steps needed to retrieve them (in practice, I actually have a few more methods but am still able to retrieve the object collection I want in one line). Is one of these methods right and the other wrong? Or is it simply a matter of preference or context dependent?

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• SCORM and the Learning Management System (LMS)

  What actually is SCORM? SCORM, Shareable Content Object Reference Model, is a standard for web-based e-learning that has been developed to define communication between client-side content and a runti... [Author: Stuart Campbell - Computers and Internet - October 05, 2009]

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• Returning null vs Throwing exceptions

  - by Svish

  Is in a bit of disagreement with a more experienced developer on this issue, and was wondering what you guys here think about this. Environment is Java, EJB 3, services, etc. The code I wrote calls a service to get things and to create things. Problem was that I got null pointer exceptions in places that didn't make sense. For example when I asked the service to create an object, I got null back. And when I tried to look up an object with an id I knew existed, I still got null back. Was like it was ignoring me. Spent some time trying to figure out what was wrong in my code (since I'm less experienced I usually assume I have messed up). Turns out the reason was security. If the user principal using my service didn't have the right permissions to use the service I called from my service, then that service simply returned null. The services that are here already are usually not documented either, so this is just something you have to know... somehow... So here is the thing: I mean that this is rather confusing as a developer interacting with this service. To me it would make much more sense if that service thew an exception which would tell me that hey, you don't have the proper permissions to get info about this thing or to create this new thing. I would then immediately know why my service wasn't working as expected. However, he argued that asking is not wrong. Exceptions should only be thrown when there is an error and asking for a thing is not an error. Even if you don't have permission to "see" that the thing you asked for. The things are often looked up in a GUI by users and for those users not having the right permissions, these things simply "do not exist". So, in short: Asking is not wrong, hence no exception. Get methods return null because to those users those things "doesn't exist". Create methods return null because nothing was created, since the user wasn't allowed to create anything. So, what do you guys think? Is this normal and/or good practice? I prefer exceptions as I prefer throwing and catching exceptions because I find it much easier to know what's going on. So I would for example also prefer to throw a NotFoundException if you asked for an id which didn't exist, rather than returning null. Anyways, just curious to what others think about this as I'm not the most experienced developer yet.

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• How to sort a ListView control by a column in Visual C#

  - by bconlon

  Microsoft provide an article of the same name (previously published as Q319401) and it shows a nice class 'ListViewColumnSorter ' for sorting a standard ListView when the user clicks the column header. This is very useful for String values, however for Numeric or DateTime data it gives odd results. E.g. 100 would come before 99 in an ascending sort as the string compare sees 1 < 9. So my challenge was to allow other types to be sorted. This turned out to be fairly simple as I just needed to create an inner class in ListViewColumnSorter which extends the .Net CaseInsensitiveComparer class, and then use this as the ObjectCompare member's type. Note: Ideally we would be able to use IComparer as the member's type, but the Compare method is not virtual in CaseInsensitiveComparer , so we have to create an exact type: public class ListViewColumnSorter : IComparer {     private CaseInsensitiveComparer ObjectCompare;     private MyComparer ObjectCompare;     ... rest of Microsofts class implementation... } Here is my private inner comparer class, note the 'new int Compare' as Compare is not virtual, and also note we pass the values to the base compare as the correct type (e.g. Decimal, DateTime) so they compare correctly: private class MyComparer : CaseInsensitiveComparer {     public new int Compare(object x, object y)     {         try         {             string s1 = x.ToString();             string s2 = y.ToString();               // check for a numeric column             decimal n1, n2 = 0;             if (Decimal.TryParse(s1, out n1) && Decimal.TryParse(s2, out n2))                 return base.Compare(n1, n2);             else             {                 // check for a date column                 DateTime d1, d2;                 if (DateTime.TryParse(s1, out d1) && DateTime.TryParse(s2, out d2))                     return base.Compare(d1, d2);             }         }         catch (ArgumentException) { }           // just use base string compare         return base.Compare(x, y);     } } You could extend this for other types, even custom classes as long as they support ICompare. Microsoft also have another article How to: Sort a GridView Column When a Header Is Clicked that shows this for WPF, which looks conceptually very similar. I need to test it out to see if it handles non-string types. #

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• Handling permissions in a MVP application

  - by Chathuranga

  In a windows forms payroll application employing MVP pattern (for a small scale client) I'm planing user permission handling as follows (permission based) as basically its implementation should be less complicated and straight forward. NOTE : System could be simultaneously used by few users (maximum 3) and the database is at the server side. This is my UserModel. Each user has a list of permissions given for them. class User { string UserID { get; set; } string Name { get; set; } string NIC {get;set;} string Designation { get; set; } string PassWord { get; set; } List <string> PermissionList = new List<string>(); bool status { get; set; } DateTime EnteredDate { get; set; } } When user login to the system it will keep the current user in memory. For example in BankAccountDetailEntering view I control the controller permission as follows. public partial class BankAccountDetailEntering : Form { bool AccountEditable {get; set;} private void BankAccountDetailEntering_Load(object sender, EventArgs e) { cmdEditAccount.enabled = false; OnLoadForm (sender, e); // Event fires... If (AccountEditable ) { cmdEditAccount.enabled=true; } } } In this purpose my all relevant presenters (like BankAccountDetailPresenter) should aware of UserModel as well in addition to the corresponding business Model it is presenting to the View. class BankAccountDetailPresenter { BankAccountDetailEntering _View; BankAccount _Model; User _UserModel; DataService _DataService; BankAccountDetailPresenter( BankAccountDetailEntering view, BankAccount model, User userModel, DataService dataService ) { _View=view; _Model = model; _UserModel = userModel; _DataService = dataService; WireUpEvents(); } private void WireUpEvents() { _View.OnLoadForm += new EventHandler(_View_OnLoadForm); } private void _View_OnLoadForm(Object sender, EventArgs e) { foreach(string s in _UserModel.PermissionList) { If( s =="CanEditAccount") { _View.AccountEditable =true; return; } } } public Show() { _View.ShowDialog(); } } So I'm handling the user permissions in the presenter iterating through the list. Should this be performed in the Presenter or View? Any other more promising ways to do this? Thanks.

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• Drawing multiple Textures as tilemap

  - by DocJones

  I am trying to draw a 2d game map and the objects on the map in a single pass. Here is my OpenGL initialization code // Turn off unnecessary operations glDisable(GL_DEPTH_TEST); glDisable(GL_LIGHTING); glDisable(GL_CULL_FACE); glDisable(GL_STENCIL_TEST); glDisable(GL_DITHER); glEnable(GL_BLEND); glEnable(GL_TEXTURE_2D); // activate pointer to vertex & texture array glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); My drawing code is being called by a NSTimer every 1/60 s. Here is the drawing code of my world object: - (void) draw:(NSRect)rect withTimedDelta:(double)d { GLint *t; glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, [_textureManager textureByName:@"blocks"]); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE); for (int x=0; x<[_map getWidth] ; x++) { for (int y=0; y<[_map getHeight] ; y++) { GLint v[] = { 16*x ,16*y, 16*x+16,16*y, 16*x+16,16*y+16, 16*x ,16*y+16 }; t=[_textureManager getBlockWithNumber:[_map getBlockAtX:x andY:y]]; glVertexPointer(2, GL_INT, 0, v); glTexCoordPointer(2, GL_INT, 0, t); glDrawArrays(GL_QUADS, 0, 4); } } } (_textureManager is a Singelton only loading a texture once!) The object drawing codes is identical (except the nested loops) in terms of OpenGL calls: - (void) drawWithTimedDelta:(double)d { GLint *t; GLint v[] = { 16*xpos ,16*ypos, 16*xpos+16,16*ypos, 16*xpos+16,16*ypos+16, 16*xpos ,16*ypos+16 }; glBindTexture(GL_TEXTURE_2D, [_textureManager textureByName:_textureName]); t=[_textureManager getBlockWithNumber:12]; glVertexPointer(2, GL_INT, 0, v); glTexCoordPointer(2, GL_INT, 0, t); glDrawArrays(GL_QUADS, 0, 4); } As soon as my central drawing routine calls the two drawing methods the second call overlays the first one. i would expect the call to world.draw to draw the map and "stamp" the objects upon it. Debugging shows me, that the first call is performed correctly (world is being drawn), but the following call to all objects ONLY draws the objects, the rest of the scene is getting black. I think i need to blend the drawn textures, but i cant seem to figure out how. Any help is appreciated. Thanks PS: Here is the github link to the project. It may not be in sync of my post here, but for some more in-depth analysis it may help.

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• LINQ: Enhancing Distinct With The SelectorEqualityComparer

  - by Paulo Morgado

  On my last post, I introduced the PredicateEqualityComparer and a Distinct extension method that receives a predicate to internally create a PredicateEqualityComparer to filter elements. Using the predicate, greatly improves readability, conciseness and expressiveness of the queries, but it can be even better. Most of the times, we don’t want to provide a comparison method but just to extract the comaprison key for the elements. So, I developed a SelectorEqualityComparer that takes a method that extracts the key value for each element. Something like this: public class SelectorEqualityComparer<TSource, Tkey> : EqualityComparer<TSource> where Tkey : IEquatable<Tkey> { private Func<TSource, Tkey> selector; public SelectorEqualityComparer(Func<TSource, Tkey> selector) : base() { this.selector = selector; } public override bool Equals(TSource x, TSource y) { Tkey xKey = this.GetKey(x); Tkey yKey = this.GetKey(y); if (xKey != null) { return ((yKey != null) && xKey.Equals(yKey)); } return (yKey == null); } public override int GetHashCode(TSource obj) { Tkey key = this.GetKey(obj); return (key == null) ? 0 : key.GetHashCode(); } public override bool Equals(object obj) { SelectorEqualityComparer<TSource, Tkey> comparer = obj as SelectorEqualityComparer<TSource, Tkey>; return (comparer != null); } public override int GetHashCode() { return base.GetType().Name.GetHashCode(); } private Tkey GetKey(TSource obj) { return (obj == null) ? (Tkey)(object)null : this.selector(obj); } } Now I can write code like this: .Distinct(new SelectorEqualityComparer<Source, Key>(x => x.Field)) And, for improved readability, conciseness and expressiveness and support for anonymous types the corresponding Distinct extension method: public static IEnumerable<TSource> Distinct<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> selector) where TKey : IEquatable<TKey> { return source.Distinct(new SelectorEqualityComparer<TSource, TKey>(selector)); } And the query is now written like this: .Distinct(x => x.Field) For most usages, it’s simpler than using a predicate.

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• Game programming course materials: What should it include?

  - by Esa

  I am tasked to create the course materials for a game programming class, and I’d like your opinion on what aspects and areas of game programming, such as game state management, game object storing or simple AI, should I include in it? The course is intented to be the first step into game programming for students with novice skills in programming. There will be mathematics as well, but I found that there are multiple questions, with good answers, on that subject already.

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• Persisting Session Between Different Browser Instances

  - by imran_ku07

      Introduction:          By default inproc session's identifier cookie is saved in browser memory. This cookie is known as non persistent cookie identifier. This simply means that if the user closes his browser then the cookie is immediately removed. On the other hand cookies which stored on the user’s hard drive and can be reused for later visits are called persistent cookies. Persistent cookies are less used than nonpersistent cookies because of security. Simply because nonpersistent cookies makes session hijacking attacks more difficult and more limited. If you are using shared computer then there are lot of chances that your persistent session will be used by other shared members. However this is not always the case, lot of users desired that their session will remain persisted even they open two instances of same browser or when they close and open a new browser. So in this article i will provide a very simple way to persist your session even the browser is closed.   Description:          Let's create a simple ASP.NET Web Application. In this article i will use Web Form but it also works in MVC. Open Default.aspx.cs and add the following code in Page_Load.    protected void Page_Load(object sender, EventArgs e)        {            if (Session["Message"] != null)                Response.Write(Session["Message"].ToString());            Session["Message"] = "Hello, Imran";        }          This page simply shows a message if a session exist previously and set the session.          Now just run the application, you will just see an empty page on first try. After refreshing the page you will see the Message "Hello, Imran". Now just close the browser and reopen it or just open another browser instance, you will get the exactly same behavior when you run your application first time . Why the session is not persisted between browser instances. The simple reason is non persistent session cookie identifier. The session cookie identifier is not shared between browser instances. Now let's make it persistent.          To make your application share session between different browser instances just add the following code in global.asax.    protected void Application_PostMapRequestHandler(object sender, EventArgs e)           {               if (Request.Cookies["ASP.NET_SessionIdTemp"] != null)               {                   if (Request.Cookies["ASP.NET_SessionId"] == null)                       Request.Cookies.Add(new HttpCookie("ASP.NET_SessionId", Request.Cookies["ASP.NET_SessionIdTemp"].Value));                   else                       Request.Cookies["ASP.NET_SessionId"].Value = Request.Cookies["ASP.NET_SessionIdTemp"].Value;               }           }          protected void Application_PostRequestHandlerExecute(object sender, EventArgs e)        {             HttpCookie cookie = new HttpCookie("ASP.NET_SessionIdTemp", Session.SessionID);               cookie.Expires = DateTime.Now.AddMinutes(Session.Timeout);               Response.Cookies.Add(cookie);         }          This code simply state that during Application_PostRequestHandlerExecute(which is executed after HttpHandler) just add a persistent cookie ASP.NET_SessionIdTemp which contains the value of current user SessionID and sets the timeout to current user session timeout.          In Application_PostMapRequestHandler(which is executed just before th session is restored) we just check whether the Request cookie contains ASP.NET_SessionIdTemp. If yes then just add or update ASP.NET_SessionId cookie with ASP.NET_SessionIdTemp. So when a new browser instance is open, then a check will made that if ASP.NET_SessionIdTemp exist then simply add or update ASP.NET_SessionId cookie with ASP.NET_SessionIdTemp.          So run your application again, you will get the last closed browser session(if it is not expired).   Summary:          Persistence session is great way to increase the user usability. But always beware the security before doing this. However there are some cases in which you might need persistence session. In this article i just go through how to do this simply. So hopefully you will again enjoy this simple article too.

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• Internal Mutation of Persistent Data Structures

  - by Greg Ros

  To clarify, when I mean use the terms persistent and immutable on a data structure, I mean that: The state of the data structure remains unchanged for its lifetime. It always holds the same data, and the same operations always produce the same results. The data structure allows Add, Remove, and similar methods that return new objects of its kind, modified as instructed, that may or may not share some of the data of the original object. However, while a data structure may seem to the user as persistent, it may do other things under the hood. To be sure, all data structures are, internally, at least somewhere, based on mutable storage. If I were to base a persistent vector on an array, and copy it whenever Add is invoked, it would still be persistent, as long as I modify only locally created arrays. However, sometimes, you can greatly increase performance by mutating a data structure under the hood. In more, say, insidious, dangerous, and destructive ways. Ways that might leave the abstraction untouched, not letting the user know anything has changed about the data structure, but being critical in the implementation level. For example, let's say that we have a class called ArrayVector implemented using an array. Whenever you invoke Add, you get a ArrayVector build on top of a newly allocated array that has an additional item. A sequence of such updates will involve n array copies and allocations. Here is an illustration: However, let's say we implement a lazy mechanism that stores all sorts of updates -- such as Add, Set, and others in a queue. In this case, each update requires constant time (adding an item to a queue), and no array allocation is involved. When a user tries to get an item in the array, all the queued modifications are applied under the hood, requiring a single array allocation and copy (since we know exactly what data the final array will hold, and how big it will be). Future get operations will be performed on an empty cache, so they will take a single operation. But in order to implement this, we need to 'switch' or mutate the internal array to the new one, and empty the cache -- a very dangerous action. However, considering that in many circumstances (most updates are going to occur in sequence, after all), this can save a lot of time and memory, it might be worth it -- you will need to ensure exclusive access to the internal state, of course. This isn't a question about the efficacy of such a data structure. It's a more general question. Is it ever acceptable to mutate the internal state of a supposedly persistent or immutable object in destructive and dangerous ways? Does performance justify it? Would you still be able to call it immutable? Oh, and could you implement this sort of laziness without mutating the data structure in the specified fashion?

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• Data Holder Framework

  - by csharp-source.net

  Data Holder is an open source .net object/relational mapper written in c#. It provides typed data ecapsulation and database persistence for .net applications. It also contains a wizzard for generating the data objects and persistance c# code. Right now it has persistence implementation only for MSQL 2000/2005.

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