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• How to model parent to child pair in MySQL (SQL)

  - by mikeschuld

  I have a data model that includes element types Stage, Actor, and Form. Logically, Stages can be assigned pairs of ( Form <--- Actor ) which can be duplicated many times (i.e. same person and same form added to the same stage at a later date/time). Right now I am modeling this with these tables: Stage Form Actor Form_Actor _______________ |Id | |FormId | --> Id in Form |ActorId | --> Id in Actor Stage_FormActor __________________ |Id | |StageId | --> Id in Stage |FormActorId | --> Id in Form_Actor I am using CodeSmith to generate the data layer for this setup and none of the templates really know how to handle this type of relationship correctly when generating classes. Ideally, the ORM would have Stage.FormActors where FormActor would be the pair Form, Actor. Is this the correct way to model these relationships. I have tried using all three Ids in one table as well Stage_Form_Actor ______________ |Id | |StageId | --> Id in Stage |FormId | --> Id in Form |ActorId | --> Id in Actor This doesn't really get generated very well either. Ideas?

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• Delphi RTTI unable to find interface

  - by conciliator

  I'm trying to fetch an interface using D2010 RTTI. program rtti_sb_1; {$APPTYPE CONSOLE} {$M+} uses SysUtils, Rtti, mynamespace in 'mynamespace.pas'; var ctx: TRttiContext; RType: TRttiType; MyClass: TMyIntfClass; begin ctx := TRttiContext.Create; MyClass := TMyIntfClass.Create; // This prints a list of all known types, including some interfaces. // Unfortunately, IMyPrettyLittleInterface doesn't seem to be one of them. for RType in ctx.GetTypes do WriteLn(RType.Name); // Finding the class implementing the interface is easy. RType := ctx.FindType('mynamespace.TMyIntfClass'); // Finding the interface itself is not. RType := ctx.FindType('mynamespace.IMyPrettyLittleInterface'); MyClass.Free; ReadLn; end. Both IMyPrettyLittleInterface and TMyIntfClass = class(TInterfacedObject, IMyPrettyLittleInterface) are declared in mynamespace.pas. Do anyone know why this doesn't work? Is there a way to solve my problem? Thanks in advance!

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• Problem in filtering records using Dataview (C#3.0)

  - by Newbie

  I have a data table . The data table is basically getting populated from excel sheet. And there are many excel sheets. Henceforth, I have written a utility method for accomplishing the same. Now in some of the excel sheets, there are date columns and in some it is not(only text/string). My function is populating the values properly into the datatable from the excell sheet. But there are many blank rows in the excel sheets some are filled with NULL , some with " ". So I need to filter those records (which are NULL or " " ) first before further processing. What I am after is to use a dataview and apply the filter over there. DataView dv = dataTable.DefaultView; dv.RowFilter = ColumnName + " <> ''"; Well by using metedata (GetOleDbSchemaTable(OleDbSchemaGuid.Columns, restrection)) I was able to get the column names from the excel sheet , so getting the column names is not an issue. But the problem is as I said in some Excel sheet there are date fileds some are not. So the Filter condition of the Dataview needs to be proper. If I apply the above logic, and if it encounters a Datafield, it is throwing error Cannot perform '<' operation on System.DateTime and System.String. Could you people please help me out? I need to filter columns(not known at compile time + their data types) which can have NULL and " " I am using C#3.0 Thanks

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• How do you manually set a RadioGroup value in wicket?

  - by Kane

  I'm trying to change the selected radio button in a Wicket RadioGroup during an AjaxEventBehavior but can't figure out how to do so. Specifically when a user types some text in a textbox I want to change the selected radio button to one I specify. How do you do this? Here's what I have so far (it crashes on addComponent): myRadioGroup = new RadioGroup("MyNewGroup", new PropertyModel(getPojo(), "selectedGroup")); Radio internalRadio = new Radio("InternalDirectoryNumber", new Model("Internal")); myRadioGroup .add(internalRadio); Radio externalRadio = new Radio("OtherMobileNumber", new Model("External")); myRadioGroup .add(externalRadio); TextField myTxtField= new TextField("TextBoxPrivateNumber", new PropertyModel(getVoiceItem(), "privateMobilePhone")); myTxtField.add( new AjaxEventBehavior( "onKeyUp" ) { @Override protected void onEvent(AjaxRequestTarget target) { Component component = target.getPage().get("myForm:MyNewGroup").setDefaultModelObject("External"); target.addComponent(component); //this causes an exception } }); myRadioGroup .add(myTxtField); Here is the exception that's thrown. java.lang.IllegalArgumentException: cannot update component that does not have setOutputMarkupId property set to true. Component: [MarkupContainer [Component id = myRadioGroup]] What's the proper way to do this? I'm not finding a whole lot of wicket documentation for this online.

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• Saving "heavy" image to PDF in MATLAB - rendering problem

  - by yuk

  I generate a figure in MATLAB with lot amount of points (100000+) and want to save it into a PDF file. With zbuffer or painters renderer I've got very large and slowly opened file (over 4 Mb) - all points are in vector format. Using OpenGL renderer rasterize the figure in PDF, ok for the plot, but not good for text labels. The file size is about 150 Kb. Try this simplified code, for example: x=linspace(1,10,100000); y=sin(x)+randn(size(x)); plot(x,y,'.') set(gcf,'Renderer','zbuffer') print -dpdf -r300 testpdf_zb set(gcf,'Renderer','painters') print -dpdf -r300 testpdf_pa set(gcf,'Renderer','opengl') print -dpdf -r300 testpdf_op The actual figure is much more complex with several axes and different types of plots. Is there a way to rasterize the figure, but keep text labels as vectors? Another problem with OpenGL is that is does not work in terminal mode (-nosplash -nodesktop) under Mac OSX. Looks like OpenGL is not supported. I have to use terminal mode for automation. The MATLAB version I run is 2007b. Mac OSX server 10.4.

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• hadoop implementing a generic list writable

  - by Guruprasad Venkatesh

  I am working on building a map reduce pipeline of jobs(with one MR job's output feeding to another as input). The values being passed around are fairly complex, in that there are lists of different types and hash maps with values as lists. Hadoop api does not seem to have a ListWritable. Am trying to write a generic one, but it seems i can't instantiate a generic type in my readFields implementation, unless i pass in the class type itself: public class ListWritable<T extends Writable> implements Writable { private List<T> list; private Class<T> clazz; public ListWritable(Class<T> clazz) { this.clazz = clazz; list = new ArrayList<T>(); } @Override public void write(DataOutput out) throws IOException { out.writeInt(list.size()); for (T element : list) { element.write(out); } } @Override public void readFields(DataInput in) throws IOException{ int count = in.readInt(); this.list = new ArrayList<T>(); for (int i = 0; i < count; i++) { try { T obj = clazz.newInstance(); obj.readFields(in); list.add(obj); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } } } } But hadoop requires all writables to have a no argument constructor to read the values back. Has anybody tried to do the same and solved this problem? TIA.

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• Tips on designing a .NET API for future use with F#

  - by Drew Noakes

  I'm in the process of designing a .NET API to allow developers to create RoboCup agents for the 3D simulated soccer league. I'm pretty happy with how the API work with C# code, however I would like to use this project to improve my F# skill (which is currently based on reading rather than practice). So I would like to ask what kinds of things I should consider when designing an API that is to be consumed by both C# and F# code. Some points. I make fairly heavy use of matrix and vector math. These are currently immutable classes/structs. The API currently defines a few interfaces with the consumer implements (eg: IAgent), using instances of their implementations (eg: MyAgent) to construct other API classes (eg: new Client(myAgent)). The API fires events. The API exposes a few delegate types. The API includes several enums. I'd like to release a version of the API as soon as possible and don't want to make major changes to it later if I realise it's too difficult to work with from F#. Any advice is appreciated.

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• Algorithm for optimally choosing actions to perform a task

  - by Jules

  There are two data types: tasks and actions. An action costs a certain time to complete, and a set of tasks this actions consists of. A task has a set of actions, and our job is to choose one of them. So: class Task { Set<Action> choices; } class Action { float time; Set<Task> dependencies; } For example the primary task could be "Get a house". The possible actions for this task: "Buy a house" or "Build a house". The action "Build a house" costs 10 hours and has the dependencies "Get bricks" and "Get cement", etcetera. The total time is the sum of all the times of the actions required to perform. We want to choose actions such that the total time is minimal. Note that the dependencies can be diamond shaped. For example "Get bricks" could require "Get a car" (to transport the bricks) and "Get cement" would also require a car. Even if you do "Get bricks" and "Get cement" you only have to count the time it takes to get a car once. Note also that the dependencies can be circular. For example "Money" - "Job" - "Car" - "Money". This is no problem for us, we simply select all of "Money", "Job" and "Car". The total time is simply the sum of the time of these 3 things. Mathematical description: Let actions be the chosen actions. valid(task) = ?action ? task.choices. (action ? actions ? ?tasks ? action.dependencies. valid(task)) time = sum {action.time | action ? actions} minimize time subject to valid(primaryTask)

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• Simply doing modelType.ToString() isn't sufficient, How can i use it via Activator.CreateInstance?

  - by programmerist

  public class MyController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class CompanyView { public static List<Personel> GetPersonel() { MyController controller = new MyController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { xyz, klm, tucyz, Company } Yes, I agree Activator.CreateInstance() is very useful. Unfortunately, I need to pass in the correct type. That means building the correct string to pass to Type.GetType(). If I trace through the call to Controller.CreatebyEnum() in the code I posted above, simply doing modelType.ToString() isn't sufficient, even for the case of DataModelType.Company. My solution'll be maintenance bottleneck. What would be better is something that takes the results of modelType.ToString() and then recursively searches through all the types found in all the assemblies loaded in the current AppDomain. According to MSDN, Type.GetType() only searches the current calling assembly, and mscorlib.dll. How can i do that? . i need best performance?

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• ASP.NET MVC application architecture "guidelines"

  - by Joe Future

  I'm looking for some feedback on my ASP.NET MVC based CMS application architecture. Domain Model - depends on nothing but the System classes to define types. For now, mostly anemic. Repository Layer - abstracted data access, only called by the services layer Services Layer - performs business logic on domain models. Exposes view models to the controllers. ViewModelMapper - service that translates back and forth between view models and domain models Controllers - super thin "traffic cop" style functionality that interacts with the service layer and only talks in terms of view models, never domain models My domain model is mostly used as data transfer (DTO) objects and has minimal logic at the moment. I'm finding this is nice because it depends on nothing (not even classes in the services layer). The services layer is a bit tricky... I only want the controllers to have access to viewmodels for ease of GUI programming. However, some of the services need to talk to each other. For example, I have an eventing service that notifies other listener services when content is tagged, when blog posts are created, etc. Currently, the methods that take domain models as inputs or return them are marked internal so they can't be used by the controllers. Sounds like overkill? Not enough abstraction? I'm mainly doing this as a learning exercise in being strict about architecture, not for an actual product, so please no feedback along the lines of "right depends on what you want to do". thanks! Jason

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• Function should return float, but it gets messed up!

  - by Andre

  Hi guys, I'm going crazy here. I have a function that should return a float number: - (float) getHue:(UIColor *)original { NSLog(@"getHue"); const CGFloat *componentColors = CGColorGetComponents(original.CGColor); float red = componentColors[0]; float green = componentColors[1]; float blue = componentColors[2]; float h = 0.0f; float maxChannel = fmax(red, fmax(green, blue)); float minChannel = fmin(red, fmin(green, blue)); if (maxChannel == minChannel) h = 0.0f; else if (maxChannel == red) h = 0.166667f * (green - blue) / (maxChannel - minChannel) + 0.000000f; else if (maxChannel == green) h = 0.166667f * (blue - red) / (maxChannel - minChannel) + 0.333333f; else if (maxChannel == blue) h = 0.166667f * (red - green) / (maxChannel - minChannel) + 0.666667f; else h = 0.0f; if (h < 0.0f) h += 1.0f; NSLog(@"getHue results: %f", h); return h; } The NSLog will trace it correctly (i.e: 0.005), but the actual return value of the function is NULL. I've tried getting that value in so many ways and it never works. float originalHue = [self getHue:original]; results in a building error, as it says: "incompatible types in initialization" float *originalHue = [self getHue:original]; results in a null return. I've tried other ways, but it never actually gets the value properly. Any thoughts? Cheers guys, Andre

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• REST API - why use PUT DELETE POST GET?

  - by Andre

  So -i was looking through some articles on creating REST API's. And some of them suggest using all types of HTTP requests: like PUT DELETE POST GET. So - we would create for example index.php and write API this way: $method = $_SERVER['REQUEST_METHOD']; $request = split("/", substr(@$_SERVER['PATH_INFO'], 1)); switch ($method) { case 'PUT': ....some put action.... break; case 'POST': ....some post action.... break; case 'GET': ....some get action.... break; case 'DELETE': ....some delete action.... break; } Ok - granted - I don't know much baout web services (yet). But - wouldn't it be easier to just accept JSON object through normal $_POST and then respond in JSON as well. We can easily serialize/deserialize via php's json_encode and json_decode and do whatever we want with that data without having to deal with different HTTP request methods... Am I missing something? UPDATE 1: Ok - after digging through various API's and learning a lot about XML-RPC, JSON-RPC, SOAP, REST I came to a conclusion that this type of API is sound. Actually stack exchange is pretty much using this approach on their sites and I do think that these people know what they are doing Stack Exchange API.

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• Unboxing to unknown type

  - by Robert

  I'm trying to figure out syntax that supports unboxing an integral type (short/int/long) to its intrinsic type, when the type itself is unknown. Here is a completely contrived example that demonstrates the concept: // Just a simple container that returns values as objects struct DataStruct { public short ShortVale; public int IntValue; public long LongValue; public object GetBoxedShortValue() { return LongValue; } public object GetBoxedIntValue() { return LongValue; } public object GetBoxedLongValue() { return LongValue; } } static void Main( string[] args ) { DataStruct data; // Initialize data - any value will do data.LongValue = data.IntValue = data.ShortVale = 42; DataStruct newData; // This works if you know the type you are expecting! newData.ShortVale = (short)data.GetBoxedShortValue(); newData.IntValue = (int)data.GetBoxedIntValue(); newData.LongValue = (long)data.GetBoxedLongValue(); // But what about when you don't know? newData.ShortVale = data.GetBoxedShortValue(); // error newData.IntValue = data.GetBoxedIntValue(); // error newData.LongValue = data.GetBoxedLongValue(); // error } In each case, the integral types are consistent, so there should be some form of syntax that says "the object contains a simple type of X, return that as X (even though I don't know what X is)". Because the objects ultimately come from the same source, there really can't be a mismatch (short != long). I apologize for the contrived example, it seemed like the best way to demonstrate the syntax. Thanks.

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• What is the preferred way in C++ for converting a builtin type (int) to bool?

  - by Martin

  When programming with Visual C++, I think every developer is used to see the warning warning C4800: 'BOOL' : forcing value to bool 'true' or 'false' from time to time. The reason obviously is that BOOL is defined as int and directly assigning any of the built-in numerical types to bool is considered a bad idea. So my question is now, given any built-in numerical type (int, short, ...) that is to be interpreted as a boolean value, what is the/your preferred way of actually storing that value into a variable of type bool? Note: While mixing BOOL and bool is probably a bad idea, I think the problem will inevitably pop up whether on Windows or somewhere else, so I think this question is neither Visual-C++ nor Windows specific. Given int nBoolean; I prefer this style: bool b = nBoolean?true:false; The following might be alternatives: bool b = !!nBoolean; bool b = (nBoolean != 0); Is there a generally preferred way? Rationale? I should add: Since I only work with Visual-C++ I cannot really say if this is a VC++ specific question or if the same problem pops up with other compilers. So it would be interesting to specifically hear from g++ or users how they handle the int-bool case. Regarding Standard C++: As David Thornley notes in a comment, the C++ Standard does not require this behavior. In fact it seems to explicitly allow this, so one might consider this a VC++ weirdness. To quote the N3029 draft (which is what I have around atm.): 4.12 Boolean conversions [conv.bool] A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type bool. A zero value, null pointer value, or null member pointer value is converted to false; any other value is converted to true. (...)

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• Passing an arbitrary JSONValue to a JSNI function

  - by Riley Lark

  I have a JSONValue in my Java that may be a JSONArray, a JSONObject, a JSONString, etc. I want to pass it to a JSNI function that can accept any of those types. If I naively write my JSNI as something like: public final native jsni(Object parameter) /*-{ doSomething(parameter); }-*/; public void useFunction(JSONValue value) { jsni(value); //Throws js exception at runtime :( } then I get a javascript exception, because GWT doesn't know how to convert the JSONValue to a JavaScriptObject (or native string / number value). My current workaround is public final native jsniForJSO(Object parameter) /*-{ doSomething(parameter); }-*/; public final native jsniForString(String parameter) /*-{ doSomething(parameter); }-*/; public final native jsniForNumber(double parameter) /*-{ doSomething(parameter); }-*/; public actuallyUseFunction(JSONValue value) { if (value.isObject()) { jsniForJSO(value.isObject().getJavaScriptObject()); } else if (value.isString()) { jsniForString(value.isString().stringValue()); } else { //etc } } This is a big burden for code maintainability, etc... especially if you have more than one parameter. Is there a way to generate these functions automatically, or get around this issue altogether? I've taken to wrapping everything in a JSONObject first, so I can definitely get a JavaScriptObject to pass to my jsni, but that's another clumsy mechanic.

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• Creating an application that can open files of a given format

  - by Brian Postow

  I've got an app, written in Obj-C. The info.plist has a list of file types that the app can open. I'm pretty sure that this is working because when I try to drag a file of an unacceptable type, the app doesn't highlight, but when I drag a file of an acceptable type, it does highlight, and lets me drop. When I drop, the app starts up, correctly, however, then I get a dialog saying: The document "foo.tiff" could not be opened. DocView cannot open files in the "TIFF File" format. I DO have this in my info.plist <key>CFBundleTypeExtensions</key> <array> <string>tif</string> <string>tiff</string> </array> <key>CFBundleTypeIconFile</key> <string>TIFFFile.icns</string> <key>CFBundleTypeName</key> <string>TIFF File</string> <key>CFBundleTypeOSTypes</key> <array> <string>TIFF</string> </array> <key>CFBundleTypeRole</key> <string>Viewer</string> <key>LSHandlerRank</key> <string>Documents/</string> Thanks.

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• Question about decorator pattern and the abstract decorator class?

  - by es11

  This question was asked already here, but rather than answering the specific question, descriptions of how the decorator pattern works were given instead. I'd like to ask it again because the answer is not immediately evident to me just by reading how the decorator pattern works (I've read the wikipedia article and the section in the book Head First Design Patterns). Basically, I want to know why an abstract decorator class must be created which implements (or extends) some interface (or abstract class). Why can't all the new "decorated classes" simply implement (or extend) the base abstract object themselves (instead of extending the abstract decorator class)? To make this more concrete I'll use the example from the design patterns book dealing with coffee beverages: There is an abstract component class called Beverage Simple beverage types such as HouseBlend simply extend Beverage To decorate beverage, an abstract CondimentDecorator class is created which extends Beverage and has an instance of Beverage Say we want to add a "milk" condiment, a class Milk is created which extends CondimentDecorator I'd like to understand why we needed the CondimentDecorator class and why the class Milk couldn't have simply extended the Beverage class itself and been passed an instance of Beverage in its constructor. Hopefully this is clear...if not I'd simply like to know why is the abstract decorator class necessary for this pattern? Thanks. Edit: I tried to implement this, omitting the abstract decorator class, and it seems to still work. Is this abstract class present in all descriptions of this pattern simply because it provides a standard interface for all of the new decorated classes?

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• Dynamically overriding an abstract method in c#

  - by ng

  I have the following abstract class public abstract class AbstractThing { public String GetDescription() { return "This is " + GetName(); } public abstract String GetName(); } Now I would like to implement some new dynamic types from this like so. AssemblyName assemblyName = new AssemblyName(); assemblyName.Name = "My.TempAssembly"; AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("DynamicThings"); TypeBuilder typeBuilder = moduleBuilder.DefineType(someName + "_Thing", TypeAttributes.Public | TypeAttributes.Class, typeof(AbstractThing)); MethodBuilder methodBuilder = typeBuilder.DefineMethod("GetName", MethodAttributes.Public | MethodAttributes.ReuseSlot | MethodAttributes.Virtual | MethodAttributes.HideBySig, null, Type.EmptyTypes); ILGenerator msil = methodBuilder.GetILGenerator(); msil.EmitWriteLine(selectionList); msil.Emit(OpCodes.Ret); However when I try to instantiate via typeBuilder.CreateType(); I get an exception saying that there is no implementation for GetName. Is there something I am doing wrong here. I can not see the problem. Also, what would be the restrictions on instantiating such a class by name? For instance if I tried to instantiate via "My.TempAssembly.x_Thing" would it be availble for instantiation without the Type generated?

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• What's a good Java-based Master-Slave communication mechanism?

  - by plecong

  I'm creating a Java application that requires master-slave communication between JVMs, possibly residing on the same physical machine. There will be a "master" server running inside a JEE application server (i.e. JBoss) that will have "slave" clients connect to it and dynamically register itself for communication (that is the master will not know the IP addresses/ports of the slaves so cannot be configured in advance). The master server acts as a controller that will dole work out to the slaves and the slaves will periodically respond with notifications, so there would be bi-directional communication. I was originally thinking of RPC-based systems where each side would be a server, but it could get complicated, so I'd prefer a mechanism where there's an open socket and they talk back and forth. I'm looking for a communication mechanism that would be low-latency where the messages would be mostly primitive types, so no serious serialization is necessary. Here's what I've looked at: RMI JMS: Built-in to Java, the "slave" clients would connect to the existing ConnectionFactory in the application server. JAX-WS/RS: Both master and slave would be servers exposing an RPC interface for bi-directional communication. JGroups/Hazelcast: Use shared distributed data structures to facilitate communication. Memcached/MongoDB: Use these as "queues" to facilitate communication, though the clients would have to poll so there would be some latency. Thrift: This does seem to keep a persistent connection, but not sure how to integrate/embed a Thrift server into JBoss WebSocket/Raw Socket: This would work, but require a lot more custom code than I'd like. Is there any technology I'm missing? Edit: Also looked at: JMX: Have the client connect to JBoss' JMX server and receive JMX notifications for bidirectional comms.

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• database setup for web application

  - by vbNewbie

  I have an application that requires a database and I have already setup tables but not sure if they match the requirements of the app. The app is a crawler which fetches web urls, crawls and stores appropriate urls and posts and all this is based on client requests which are stored as projects. So for each url stored there is one post and for client there are many projects and for each project there are many types of requests. So we get a client with a request and assign them a project name and then use the request to search for content and store the url and post. A request could already exist and should not be duplicated but should be associated with the right client and project and post etc. Here is my schema now: url table: urlId PK queryId FK url post table: postId PK urlId FK post date request table: queryId PK request client table: clientId PK client Name projectId FK project table: projectID PK queryID FK project Does this look right? or does anyone have suggestions. Of course my stored procedures and insert statements will have to be in depth.

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• C++ interpreter conceptual problem

  - by Jan Wilkins

  I've built an interpreter in C++ for a language created by me. One main problem in the design was that I had two different types in the language: number and string. So I have to pass around a struct like: class myInterpreterValue { myInterpreterType type; int intValue; string strValue; } Objects of this class are passed around million times a second during e.g.: a countdown loop in my language. Profiling pointed out: 85% of the performance is eaten by the allocation function of the string template. This is pretty clear to me: My interpreter has bad design and doesn't use pointers enough. Yet, I don't have an option: I can't use pointers in most cases as I just have to make copies. How to do something against this? Is a class like this a better idea? vector<string> strTable; vector<int> intTable; class myInterpreterValue { myInterpreterType type; int locationInTable; } So the class only knows what type it represents and the position in the table This however again has disadvantages: I'd have to add temporary values to the string/int vector table and then remove them again, this would eat a lot of performance again. Help, how do interpreters of languages like Python or Ruby do that? They somehow need a struct that represents a value in the language like something that can either be int or string.

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• Return type from DAL class (Sql ce, Linq to Sql)

  - by bretddog

  Hi, Using VS2008 and Sql CE 3.5, and preferably Linq to Sql. I'm learning database, and unsure about DAL methods return types and how/where to map the data over to my business objects: I don't want direct UI binding. A business object class UserData, and a class UserDataList (Inherits List(Of UserData)), is represented in the database by the table "Users". I use SQL Compact and run SqlMetal which creates dbml/designer.vb file. This gives me a class with a TableAttribute: <Table()> _ Partial Public Class Users I'm unsure how to use this class. Should my business object know about this class, such that the DAL can return the type Users, or List(Of Users) ? So for example the "UserDataService Class" is a part of the DAL, and would have for example the functions GetAll and GetById. Will this be correct : ? Public Class UserDataService Public Function GetAll() As List(Of Users) Dim ctx As New MyDB(connection) Dim q As List(Of Users) = From n In ctx.Users Select n Return q End Function Public Function GetById(ByVal id As Integer) As Users Dim ctx As New MyDB(connection) Dim q As Users = (From n In ctx.Users Where n.UserID = id Select n).Single Return q End Function And then, would I perhaps have a method, say in the UserDataList class, like: Public Class UserDataList Inherits List(Of UserData) Public Sub LoadFromDatabase() Me.clear() Dim database as New UserDataService dim users as List(Of Users) users = database.GetAll() For each u in users dim newUser as new UserData newUser.Id = u.Id newUser.Name = u.Name Me.Add(newUser) Next End Sub End Class Is this a sensible approach? Would appreciate any suggestions/alternatives, as this is my first attempt on a database DAL. cheers!

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• WCF service reference namespace differs from original

  - by Thorarin

  I'm having a problem regarding namespaces used by my service references. I have a number of WCF services, say with the namespace MyCompany.Services.MyProduct (the actual namespaces are longer). As part of the product, I'm also providing a sample C# .NET website. This web application uses the namespace MyCompany.MyProduct. During initial development, the service was added as a project reference to the website and uses directly. I used a factory pattern that returns an object instance that implements MyCompany.Services.MyProduct.IMyService. So far, so good. Now I want to change this to use an actual service reference. After adding the reference and typing MyCompany.Services.MyProduct in the namespace textbox, it generates classes in the namespace MyCompany.MyProduct.MyCompany.Services.MyProduct. BAD! I don't want to have to change using directives in several places just because I'm using a proxy class. So I tried prepending the namespace with global::, but that is not accepted. Note that I hadn't even deleted the original assembly references yet, and "reuse types" is enabled, but no reusing was done, apparently. However, I don't want to keep the assembly references around in my sample website for it to work anyway. The only solution I've come up with so far is setting the default namespace for my web application to MyCompany (because it cannot be empty), and adding the service reference as Services.MyProduct. Suppose that a customer wants to use my sample website as a starting point, and they change the default namespace to OtherCompany.Whatever, this will obviously break my workaround. Is there a good solution to this problem? To summarize: I want to generate a service reference proxy in the original namespace, without referencing the assembly. Note: I have seen this question, but there was no solution provided that is acceptable for my use case. Edit: As John Saunders suggested, I've submitted some feedback to Microsoft about this: Feedback item @ Microsoft Connect

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• Generic dataset handling library

  - by Pep.

  Hello, I want to build a generic Perl module for handling and analysing biomedical character separated datasets and which can, most certain, be used on any kind of datasets that contain a mixture of categorical (A,B,C,..) and continuous (1.2,3,881..) and identifier (XXX1,XXX2...). The plan is to have people initialize the module and then use some arguments to point to the data file(s), the place were the analysis reports should be placed and the structure of the data. By structure of data I mean which variable is in which place and its name/type. And this is where I need some enlightenment. I am baffled how to do this in a clean way. Obviously, having people create a simple schema file, be it XML or some other format would be the cleanest but maybe not all people enjoy doing something like this. The solutions I can think of are: Create a configuration file in XML or similar and with a prespecified format. Pass the information during initialization of the module. Use the first row of the data as headers and try to guess types (ouch) Surely there must be a "canonical" way of doing this that is also usable and efficient. Thanks p.

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• best practice - loging events (general) and changes (database)

  - by b0x0rz

  need help with logging all activities on a site as well as database changes. requirements: * should be in database * should be easily searchable by initiator (user name / session id), event (activity type) and event parameters i can think of a database design but either it involves a lot of tables (one per event) so i can log each of the parameters of an event in a separate field OR it involves one table with generic fields (7 int numeric and 7 text types) and log everything in one table with event type field determining what parameter got written where (and hoping that i don't need more than 7 fields of a certain type, or 8 or 9 or whatever number i choose)... example of entries (the usual things): [username] login failed @datetime [username] login successful @datetime [username] changed password @datetime, estimated security of password [low/ok/high/perfect] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] changed profile name from [old name] to [new name] @datetime [username] verified name with [credit card type] credit card @datetime datbase table [table name] purged of old entries @datetime etc... so anyone dealt with this before? any best practices / links you can share? i've seen it done with the generic solution mentioned above, but somehow that goes against what i learned from database design, but as you can see the sheer number of events that need to be trackable (each user will be able to see this info) is giving me headaches, BUT i do LOVE the one event per table solution more than the generic one. any thoughts? edit: also, is there maybe an authoritative list of such (likely) events somewhere? thnx stack overflow says: the question you're asking appears subjective and is likely to be closed. my answer: probably is subjective, but it is directly related to my issue i have with designing a database / writing my code, so i'd welcome any help. also i tried narrowing down the ideas to 2 so hopefully one of these will prevail, unless there already is an established solution for these kinds of things.

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