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• Rabbitmq queue sharding

  - by kolchanov

  I have to implement this scenario: An external application publish message to rabbitmq. This message has a client_id property. We can place this id to routing key or message header or some other property. I have to implement sharding in a exchange routng logic - the message should be delivered to specific queue based on the client_id range. Is it possible to implement in a standard exchanges? If not what exchange should I take as the base? How to dynamicly change client_id ranges?

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• what pattern to use for multi-argument method?

  - by Omid S

  I have a method with the following signature: foo (Sample sample, Aliquot aliquot) "foo" needs to alter a Sample object, either the first argument or from the second argument it can extract its Sample. For example: foo (Sample sample, Aliquot aliquot) { Sample out = null; if (sample != null) out = sample else out = aliquot.getSample() return out; } But that is so un-elegant, other than reading the API a developer does not know the reference of the first argument overrides the Sample of the second argument. Now, I could change "foo" to foo (SomeMagicalObject bar) where SomeMagicalObject is a tuple for Sample and Aliquot and holds some logic ... etc. But I am wondering, are there some patterns for this question?

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• Are there any tools to help the user to design a State Machine to be consumed by my application?

  - by kolrie

  When reading this question I remembered there was something I have been researching for a while now and I though Stackoverflow could be of help. I have created a framework that handles applications as state machines. Currently all the state business logic and transactions are handled via Java code. I was looking for some UI implementation that would allow the user to draw the state machines and transactions and generate a file that can later on be consumed by my framework to "run" the workflow according to one or more defined state machines. Ideally I would like to use an open standard like SCXML. The goal as the UI would be to have something like this plugin IBM have for Rational Software Architect: Do you know any editor, plugin or library that would have something similar or at least serve as a good starting point?

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• Constrain generic extension method to base types and string

  - by hitch

  I want to have an extension method for XElement/XAttribute that allows me to apply a "ValueOrDefault" logic - perhaps with various slightly different implementations: ValueOrNull, ValueOrDefault, NumericValueOrDefault (which validates if the value is numeric), but I want to constrain these methods so that they can only work with ValueTypes or String (i.e. it does not really make sense to use any other reference types. Is it possible to do this with one implementation of each method, or will I have to have one where the constraint is "Structure" and one where the constraint is "String" - if I combine Structure and String in the generic constraint, I get the error : 'Structure' constraint and a specific class type constraint cannot be combined. An example of the current method implementation is as follows: <Extension()> _ Public Function ValueOrDefault(Of T As {Structure})(ByVal xe As XElement, ByVal defaultValue As T) As T If xe Is Nothing or xe.Value = "" Then Return defaultValue End If Return CType(Convert.ChangeType(xe.Value, GetType(T)), T) End Function

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• Does DB2 have an "insert or update" statement?

  - by Mikael Eriksson

  From my code (Java) I want to ensure that a row exists in the database (DB2) after my code is executed. My code now does a select and if no result is returned it does an insert. I really don't like this code since it exposes me to concurrency issuses when running in a multi-threaded environment. What I would like to do is to put this logic in DB2 instead of in my Java code. Does DB2 have an "insert-or-update" statement? Or anything like it that I can use? For example: insertupdate into mytable values ('myid') Another way of doing it would probably be to allways do the insert and catch "SQL-code -803 primary key already exists", but I would like to avoid that if possible.

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• Web service reference location?

  - by Damien Dennehy

  I have a Visual Studio 2008 solution that's currently consisting of three projects: A DataFactory project for Business Logic/Data Access. A Web project consisting of the actual user interface, pages, controls, etc. A Web.Core project consisting of utility classes, etc. The application requires consuming a web service. Normally I'd add the service reference to the Web project, but I'm not sure if this is best practice or not. The following options are open to me: Add the reference to the Web project. Add the reference to the Web.Core project, and create a wrapper method that Web will call to consume the web service. Add a new project called Web.Services, and copy step 2. This project is expected to increase in size so I'm open to any suggestions.

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• How do views reduce code duplication?

  - by Debuger

  Hi! I read something like this about db views: Views are incredibly powerful and useful for one reason that stands out above all the other very good reasons. They reduce code duplication. That is, in most cases, the bottom line. If a query will be used in three or more places, then a view will drastically simplify your changes if the schema or query parameters change. I once had to edit 22 stored procedures to change some query logic. If the original architecture had utilized views, then I would have had only three changes. Can anyone explain to me how it works, and maybe give me some examples? Best regards!

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• How to implement following with Zend navigation?

  - by simple

  I have a top navigation and a side one Home | Tours | Booking Tour1 ------ Tour2 ------ Tour3 I show the side menu depending on a active top item. But sometimes when the side menu item is clicked I have to show that items children instead of the sidemenu. When no children exist I just show Children of a top menu depending on the active item. I an really having difficulties implementing that kind a logic and any help would be appreciated. //Comment button is not working so I will add comments here After stumbling the zend navigation view helpers, I am coming to the point - Understanding the concept of how in zend V part of MVC is implemented can save someone who is new to the framework many hours. As said in the answer to this question - "Use what is available", thought first we have to know where to find what is already available out there - that is where comes handy to take a look at the concept of helpers and so forth.

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• Using recode in R

  - by celenius

  I'm trying to use 'recode' in R (from the 'cars' package) and it is not working. I read in data from a .csv file into a data frame called 'results'. Then, I replace the values in the column 'Built_year', according to the following logic. recode(results$Built_year, "2 ='1950s';3='1960s';4='1970s';5='1980s';6='1990s';7='2000 or later'") When I check results$Built_year after doing this step, it appears to have worked. However, it does not store this value, and returns to its previous value. I don't understand why. Thanks. (at the moment something is going wrong and I can't see any of the icons for formatting)

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• Accessing constructor from abstract base class with reflection

  - by craesh

  Hi! I'm playing around with Java's Reflection. I have an abstract class Base with a constructor. abstract class Base { public Base( String foo ) { // do some magic } } I have some further classes extending Base. They don't contain much logic. I want to instantiate them with Base's constructor, without having to write some proxy contructors in those derived classes. And of course, I want to instantiate those derived classes with Reflection. Say: Class cls = SomeDerivedClass.class; Constructor constr; constr = cls.getConstructor( new Class[] { String.class } ); // will return null Class clsBase = Base.class; constr = clsBase.getConstructor( new Class[] { String.class } ); // ok Base obj = (Base) constr.newInstance( new Object[] { "foo" } ); // will throw InstantiationException because it belongs to an abstract class Any ideas, how I can instantiate a derived class with Base's constructor? Or must I declare those dumb proxy constructors?

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• XSD file, where to get xmlns argument?

  - by Daok

  <?xml version="1.0" encoding="utf-8"?> <xs:schema id="abc" targetNamespace="http://schemas.businessNameHere.com/SoftwareNameHere" elementFormDefault="qualified" xmlns="http://schemas.businessNameHere.com/SoftwareNameHere" xmlns:mstns="http://schemas.businessNameHere.com/SoftwareNameHere" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="..." type="..." /> <xs:complexType name="..."> I am working on a project using XSD to generate .cs file. My question is concerning the string "http://schemas.businessNameHere.com/SoftwareNameHere" If I change it, it doesn't work. But the http:// is not a valid one... what is the logic behind and where can I can information about what to put there or how to change it?

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• "Verbose Dictionary" in C#, 'override new' this[] or implement IDictionary

  - by Benjol

  All I want is a dictionary which tells me which key it couldn't find, rather than just saying The given key was not present in the dictionary. I briefly considered doing a subclass with override new this[TKey key], but felt it was a bit hacky, so I've gone with implementing the IDictionary interface, and passing everything through directly to an inner Dictionary, with the only additional logic being in the indexer: public TValue this[TKey key] { get { ThrowIfKeyNotFound(key); return _dic[key]; } set { ThrowIfKeyNotFound(key); _dic[key] = value; } } private void ThrowIfKeyNotFound(TKey key) { if(!_dic.ContainsKey(key)) throw new ArgumentOutOfRangeException("Can't find key [" + key + "] in dictionary"); } Is this the right/only way to go? Would newing over the this[] really be that bad?

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• How can I modify a custom object in an ASP.NET FormView based on a button click?

  - by David

  I have a FormView that modifies an instance of a custom class. The various form controls (TextBox, DropDownList etc.) are working fine. However, I want to include a Button that will modify the state of the DataItem based on some very simple logic. There is no form control which could control this change in a non-confusing way. So I tried adding a Button and modifying the state of the DataItem in the code-behind. But the problem I encounter is that the FormView's DataItem is null/nothing. From reading this SO question it seems the problem is that the item is not databound when the Button's Click event is fired. So, the question; Is it possible to get the DataItem for the FormView during a Button's Click event? and if not: what are my options for implementing this? Thanks in advance. Edit: I can include any code that might help

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• How to add Transactions with a DataSet created using the Add Connection Wizard?

  - by RoguePlanetoid

  I have a DataSet that I have added to my project where I can Insert and Add records using the Add Query function in Visual Studio 2010, however I want to add transactions to this, I have found a few examples but cannot seem to find one that works with these. I know I need to use the SQLClient.SQLTransaction Class somehow. I used the Add New Data Source Wizard and added the Tables/View/Functions I need, I just need an example using this process such as How to get the DataConnection my DataSet has used. Assuming all options have been set in the wizard and I am only using the pre-defined adapters and options asked for in this wizard, how to I add the Transaction logic to my Database. For example I have a DataSet called ProductDataSet with the XSD created for this, I have then added my Stock table as a Datasource and Added an AddStock method with a wizard, this also if a new item calls an AddItem method, if either of these fails I want to rollback the AddItem and AddStock in this case.

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• .NET Database Apps: Your Preferred Setup

  - by mdvaldosta

  I'm struggling to settle into a pattern for developing typical database driven apps in C# and Visual Studio. There are so many ways to set them up, using drag/drop datasets and adapters or writing the queries manually in ADO.NET or Linq to SQL, Linq to Entities, to bind or not to data bind etc etc. Where to store the connection string, in app.config or in a method or both etc etc. So many tutorials and all of them are different. Everytime I write something I start hating the way it looks and works, so I scrap it and start over. It's getting a bit tedious. Maybe it's alittle of the OCD in me. Would any of you professional developers out there share your method of setting up and structuring your database logic and maybe some sample code? It's really how to go about organizing the code and the method(s) of interacting with SQL that I'm trying to get into a routine with, one that works and won't get me laughed at by someone reviewing it.

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• Language Agnositc Basic Programming Question

  - by Rachel

  This is very basic question from programming point of view but as I am in learning phase, I thought I would better ask this question rather than having an misunderstanding or narrow knowledge about the topic. So do excuse me if somehow I mess it up. Question: Let say I have class A,B,C and D now class A has some piece of code which I need to have in class B,C and D so I am extending class A in class B, class C, and class D Now how can I access the function of class A in other classes, do I need to create an object of class A and than access the function of class A or as am extending A in other classes than I can internally call the function using this parameter. If possible I would really appreciate if someone can explain this concept with code sample explaining how the logic flows.

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• BLL returning the right Type of an instance

  - by Younes

  I have a class "Artikel" and there i write some Business Logic. I also have a class "tArtikel" which is a type. In my class "Artikel" I work with "tArtikel" and returns are of that type. Now when i instantiate an "Artikel" i want it to be of type "tArtikel", so what i tried in my code is: public tArtikel Artikel() { tArtikel artikel = new tArtikel(); } Which results in: "'Artikel' member names cannot be the same as their enclosing type". How would i set this up correctly?

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• Injecting an XML fragment into the current document from an external file

  - by makenai

  I'm currently parsing an XML file using REXML and trying to come up with a way of inserting an XML fragment from an internal file. Currently, I'm using some logic like the following: doc.elements.each('//include') do |element| handleInclude( element ) end def handleInclude( element ) if filename = element.attributes['file'] data = File.open( filename ).read doc = REXML::Document.new( data ) element.parent.replace_child( element, doc ) end end Where my XML looks like the following: <include file="test.xml" /> But this seems a little bit clunky, and I'm worried that REXML might not always parse XML fragments correctly due to absence of a proper root node in some cases. Is there a better way of doing this? Concern #2: REXML seems not to pick up my changes after I replace elements. For example, after making a change: doc.elements.each('rootNode/*') do |element| end ..picks up neither the original element I replaced, nor the one I replaced it with. Is there some trick to getting REXML to rescan its' tree?

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• How does SQL Server treat statements inside stored procedures with respect to transactions?

  - by Sleepless

  Hi All! Say I have a stored procedure consisting of several seperate SELECT, INSERT, UPDATE and DELETE statements. There is no explicit BEGIN TRANS / COMMIT TRANS / ROLLBACK TRANS logic. How will SQL Server handle this stored procedure transaction-wise? Will there be an implicit connection for each statement? Or will there be one transaction for the stored procedure? Also, how could I have found this out on my own using T-SQL and / or SQL Server Management Studio? Thanks!

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• Socket : can an asynchronous Receive returns without reading all the bytes I asked for?

  - by NorthWind

  Hi; I was reading an article on Vadym Stetsiak's blog about how to transfer variable length messages with async sockets (url: http://vadmyst.blogspot.com/2008/03/part-2-how-to-transfer-fixed-sized-data.html). He says : What to expect when multiple messages arrive at the server? While dealing with multiple messages one has to remember that receive operation can return arbitrary number of bytes being read from the net. Typically that size is from 0 to specified buffer length in the Receive or BeginReceive methods. So, even if I tell BeginReceive to read 100 bytes, it may read less than that and returns??? I am developing a network-enabled software (TCP/IP), and I always receive the same exact number of bytes I asked for. I don't even understand the logic : why would Receive completes asynchronously if it didn't get every byte I asked for ... just keep waiting. Maybe it has something to do with IP vs TCP? Thank you for your help.

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• Integrating JSF with Spring

  - by Abel Morelos

  I haven't implemented any code, I'm still working the overall architecture for a new application and this going to be the first time I use JSF+Spring. I need to put web services in front of the Spring service beans (business logic tier) since these beans could be accessed by other applications besides the presentation tier. While defining the different layers or tiers for the application, I feel unsure about how to integrate JSF (the presentation tier) with Spring (the business tier in this application). I'm considering to define some sort of common tier or service tier in order to provide the glue code for JSF and Spring, but before that I want to hear from others what have they done or if they have used other frameworks to help with the glue code for this scenario (I already checked Spring MVC/Spring Faces, but I'm not sure if that's what I need since I'm thinking of this application more like JSF-centric than Spring-centric, but maybe you could help me about considering another approach). Thanks in advance.

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• How to find out all versions of iPad from user-agent string?

  - by User11091981

  I wanted to find out all the version's of iPad (excluding iPhone, iPod) from user agent string, currently while testing I got the following string Mozilla/5.0 (iPad; CPU OS 5_1_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B206 Safari/7534.48.3 Question: Will the following code works fine for all the iPad's? String userAgentStr = request.getHeader("User-agent"); if (userAgentStr.contains("iPad")) { //do my logic } EDIT: I am using Dolphin browser from iPad but I am getting the following UA string: Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_1 like Mac OS X; en_US) AppleWebKit/533.17.9 (KHTML, like Gecko) Mobile/8C148 Safari/6533.18.5 Similarly iBrowser from iPad UA string is: Mozilla/5.0 (iPhone; CPU iPhone OS 5_1_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Mobile/9B206 So my above code is breaking...

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• Invoke private method with interface as argument

  - by Stephanie

  Hi, I've been attempting to invoke a private method whose argument is a parameter and I can't quite seem to get it right. Here's kind of how the code looks so far: public class TestClass { public TestClass(){ } private void simpleMethod( Map<String, Integer> testMap) { //code logic } } Then I attempt to use this to invoke the private method: //Hashmap Map <String, Integer> testMap = new HashMap <String, Integer>(); //method I want to invoke Method simpleMethod = TestClass.class.getDeclaredMethod("simpleMethod", Map.class); simpleMethod.setAccessible(true); simpleMethod.invoke(testClassObject, testMap); //Throws an IllegalArgumentException As you can see, it throws an IllegalArgumentException. I've attempted to cast the hashmap back to a map, but that didn't work. What am I doing wrong?

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• Grand Central Strategy for Opening Multiple Files

  - by user276632

  I have a working implementation using Grand Central dispatch queues that (1) opens a file and computes an OpenSSL DSA hash on "queue1", (2) writing out the hash to a new "side car" file for later verification on "queue2". I would like to open multiple files at the same time, but based on some logic that doesn't "choke" the OS by having 100s of files open and exceeding the hard drive's sustainable output. Photo browsing applications such as iPhoto or Aperture seem to open multiple files and display them, so I'm assuming this can be done. I'm assuming the biggest limitation will be disk I/O, as the application can (in theory) read and write multiple files simultaneously. Any suggestions? TIA

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• How do I use theme preprocessor functions for my own templates?

  - by Jergason

  I have several .tpl.php files for nodes, CCK fields, and Views theming. These template files have a lot of logic in them to move things around, strip links, create new links, etc. I understand that this is bad development and not "The Drupal Way". If I understand correctly, "The Drupal Way" is to use preprocessor functions in your template.php file to manipulate variables and add new variables. A few questions about that: Is there a naming convention for creating a preprocessor function for a specific theme? For example, if I have a CCK field template called content-field-field_transmission_make_model.tpl, how would I name the preprocessor function? Can I use template preprocessor functions for node templates, CCK field templates, and Views templates? Do they have different methods of modifying template variables or adding new ones?

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