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• MYSQL not running on Ubuntu OS - Error 2002.

  - by mgj

  Hi, I am a novice to mysql DB. I am trying to run the MYSQL Server on Ubuntu 10.04. Through Synaptic Package Manager I am have installed the mysql version: mysql-client-5.1 I wonder that how was the database password set for the mysql-client software that I installed through the above way.It would be nice if you could enlighten me on this. When I tried running this database, I encountered the error given below: mohnish@mohnish-laptop:/var/lib$ mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) mohnish@mohnish-laptop:/var/lib$ I referred to a similar question posted by another user. I didn't find a solution through the proposed answers. For instance when I tried the solutions posted for the similar question I got the following: mohnish@mohnish-laptop:/var/lib$ service start mysqld start: unrecognized service mohnish@mohnish-laptop:/var/lib$ ps -u mysql ERROR: User name does not exist. ********* simple selection ********* ********* selection by list ********* -A all processes -C by command name -N negate selection -G by real group ID (supports names) -a all w/ tty except session leaders -U by real user ID (supports names) -d all except session leaders -g by session OR by effective group name -e all processes -p by process ID T all processes on this terminal -s processes in the sessions given a all w/ tty, including other users -t by tty g OBSOLETE -- DO NOT USE -u by effective user ID (supports names) r only running processes U processes for specified users x processes w/o controlling ttys t by tty *********** output format ********** *********** long options *********** -o,o user-defined -f full --Group --User --pid --cols --ppid -j,j job control s signal --group --user --sid --rows --info -O,O preloaded -o v virtual memory --cumulative --format --deselect -l,l long u user-oriented --sort --tty --forest --version -F extra full X registers --heading --no-heading --context ********* misc options ********* -V,V show version L list format codes f ASCII art forest -m,m,-L,-T,H threads S children in sum -y change -l format -M,Z security data c true command name -c scheduling class -w,w wide output n numeric WCHAN,UID -H process hierarchy mohnish@mohnish-laptop:/var/lib$ which mysql /usr/bin/mysql mohnish@mohnish-laptop:/var/lib$ mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) I even tried referring to http://forums.mysql.com/read.php?11,27769,84713#msg-84713 but couldn't find anything useful. Please let me know how I could tackle this error. Thank you very much..

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• Variable Assignment and loops (Java)

  - by Raven Dreamer

  Greetings Stack Overflowers, A while back, I was working on a program that hashed values into a hashtable (I don't remember the specifics, and the specifics themselves are irrelevant to the question at hand). Anyway, I had the following code as part of a "recordInput" method. tempElement = new hashElement(someInt); while(in.hasNext() == true) { int firstVal = in.nextInt(); if (firstVal == -911) { break; } tempElement.setKeyValue(firstVal, 0); for(int i = 1; i<numKeyValues;i++) { tempElement.setKeyValue(in.nextInt(), i); } elementArray[placeValue] = tempElement; placeValue++; } // close while loop } // close method This part of the code was giving me a very nasty bug -- no matter how I finagled it, no matter what input I gave the program, it would always produce an array full of only a single value -- the last one. The problem, as I later determined it, was that because I had not created the tempElement variable within the loop, and because values were not being assigned to elementArray[] until after the loop had ended -- every term was defined rather as "tempElement" -- when the loop terminated, every slot in the array was filled with the last value tempElement had taken. I was able to fix this bug by moving the declaration of tempElement within the while loop. My question to you, Stackoverflow, is whether there is another (read: better) way to avoid this bug while keeping the variable declaration of tempElement outside the while loop. (suggestions for better title and tags also appreciated)

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• Make PasswordRecovery control work with locked out users ?

  - by Moe Sisko

  Example scenario in an ASP.NET application using SQL Server membership provider : 1) a user can't remember their exact password, and tries many times in a short space of time to login with an invalid password (say 5 times in a 10 minute window). This locks out the user (i.e. sets the IsLockedOut flag of the aspnet_Membership table to 1). 2) user goes to the "forgot my password" screen to try to get a new password emailed to them. This screen uses the PasswordRecovery control. User enters their correct user id, but then cannot go further in the password recovery process, since the IsLockedOut flag is 1. (They don't even get to see their security question). 3) The user would then have to phone tech support to get themselves unlocked etc. To reduce the burden on support staff, we are trying to eliminate step 3) if possible, by making the PasswordRecovery control (if possible), work with locked out users. i.e. when they enter their login ID, the security question comes up, and IF they enter the correct answer, the system will unlock the user, then send the new email to them. I'm wondering if it is possible to tweak the PasswordRecovery control to do this. Or maybe I'm approaching this the wrong way ?

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• How to identify a particular entity's Session Factory with Fluent NHibernate and Multiple Databases

  - by Trevor

  I've already asked this question as part of an answer to another question ( see http://stackoverflow.com/questions/2655861/fluent-nhibernate-multiple-databases ) but thought it better to ask again here. My problem is this: I'm using Fluent NHibernate. My application uses multiple databases. Each database has its own entities registered (mapped) against it. The result is that have multiple Session Factories, each one relating to a single DB, and each 'containing' its own set of mapped entities. For loading entities I've created a generic Factory class that provides some standard load methods usable for any registered entity (in any DB). The problem is: The load methods need to use the correct session factory for the entity class I'm busy dealing with. How would I determine which session factory I need to use? I have all the Session Factories 'on hand' (and indexed by database name), I just need a way, knowing just the type of Entity I'm about to load, of choosing the right Session Factory to use. For example: public IBaseBusinessObject CreatePopulatedInstance(Type boType, Guid instanceKey) { IBaseBusinessObject result = null; ISessionFactory sessionFactory = GetSessionFactory(boType); using (ISession session = sessionFactory.OpenSession()) { using (session.BeginTransaction()) { result = (IBaseBusinessObject)session.Get(boType, instanceKey); } } return result; } What needs to go on in GetSessionFactory(boType) ? Thanks for reading!

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• How to bind "rest" variables to list of values in macro in Scheme

  - by Slartibartfast

  I want to make a helper macro for writing match-extensions. I have something like this: (define-match-expander my-expander (? (stx) (let* ([dat (cdr (syntax-e stx))] [var1 (car dat))] [var2 (cadr dat)]) ;transformer goes here ))) So I wanted a macro that will do this let binding. I've started with something like this: (define-syntax-rule (define-my-expander (id vars ...) body) (define-match-expander id (? (stx) (match-let ([(vars ...) (cdr (syntax-e stx))]) body)))) but match-let isn't defined in transformation time. First question would be is there any other way of doing this (making this expanders, I mean)? Maybe there is already something similar in plt-scheme that I'm not aware of, or I'm doing it wrong in some way. Regardless of answer on the first question, if I ever want to bound list of variables to list of values inside of a macro, how should I do it? EDIT: In combination with Eli's answer macro now looks like this: (define-syntax-rule (define-my-expander (id vars ...) body) (define-match-expander id (? (stx) (syntax-case stx () [(_ vars ...) body]))))

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• Protocol specific channel handlers

  - by Mickael Marrache

  I'm writing an application server that will receive SIP and DNS messages from the network. When I receive a message from the network, I understand from the documentation that at first, I get a ChannelBuffer. I would like to determine which kind of message has been received (SIP or DNS) and to decode it. To determine the message type, I can dedicate port to each type of message, but I would be interested to know if there exist another solution for that. My question is more about how to decode the ChannelBuffer. Is there a ChannelHandler provided by Netty to decode SIP or DNS messages? If not, what would be the right place in the type hierarchy to write my custom ChannelHandler? To illustrate my question, let's take as example the HttpRequestDecoder, the hierarchy is: java.lang.Object org.jboss.netty.channel.SimpleChannelUpstreamHandler org.jboss.netty.handler.codec.frame.FrameDecoder org.jboss.netty.handler.codec.replay.ReplayingDecoder<HttpMessageDecoder.State> org.jboss.netty.handler.codec.http.HttpMessageDecoder org.jboss.netty.handler.codec.http.HttpRequestDecoder Also, do I need to use two different ChannelHandler for decoding and encoding, or is there a possibility to use a single ChannelHandler for both? Thanks

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• Zend Framework :: Is this code good for user login (Its begining- because that I want to know if its

  - by Yosef

  Hi, I new in Zend. Main Question: Is this code good for user login (Its beginning- because that I want to know if its can be improve)? Code understanding question: Is every time that in action call to his view- code execution in action not going to next row until view request? (I asking about IndexAction that I write down) Thanks view index.phtml <? echo $this->form controller IndexAction.php public function indexAction() { $form=new Application_Form_Login(); $this->view->form = $form; if ($this->getRequest()->isPost()) { $formData = $this->getRequest()->getPost(); if ($form->isValid($formData)) { echo " test value username: ".$form->getValue('username'); } } } form Login.php public function init() { $this->setMethod('post'); $this->setName('user login'); $username = new Zend_Form_Element_Text('username'); $username->setLabel("username") ->setRequired(true) ->addFilter('StripTags') ->addFilter('StringTrim') ->addValidator('NotEmpty'); $password = new Zend_Form_Element_Password('password'); $password->setLabel('password') ->setRequired(true) ->addFilter('StripTags') ->addFilter('StringTrim') ->addValidator('NotEmpty'); $submit = new Zend_Form_Element_Submit('submit'); $this->addElements(array($username, $password, $submit)); }

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• Ignore case in Python strings

  - by Paul Oyster

  What is the easiest way to compare strings in Python, ignoring case? Of course one can do (str1.lower() <= str2.lower()), etc., but this created two additional temporary strings (with the obvious alloc/g-c overheads). I guess I'm looking for an equivalent to C's stricmp(). [Some more context requested, so I'll demonstrate with a trivial example:] Suppose you want to sort a looong list of strings. You simply do theList.sort(). This is O(n * log(n)) string comparisons and no memory management (since all strings and list elements are some sort of smart pointers). You are happy. Now, you want to do the same, but ignore the case (let's simplify and say all strings are ascii, so locale issues can be ignored). You can do theList.sort(key=lambda s: s.lower()), but then you cause two new allocations per comparison, plus burden the garbage-collector with the duplicated (lowered) strings. Each such memory-management noise is orders-of-magnitude slower than simple string comparison. Now, with an in-place stricmp()-like function, you do: theList.sort(cmp=stricmp) and it is as fast and as memory-friendly as theList.sort(). You are happy again. The problem is any Python-based case-insensitive comparison involves implicit string duplications, so I was expecting to find a C-based comparisons (maybe in module string). Could not find anything like that, hence the question here. (Hope this clarifies the question).

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• Does Java 6 open a default port for JMX remote connections?

  - by Bob Cross

  My specific question has to do with JMX as used in JDK 1.6: if I am running a Java process using JRE 1.6 with com.sun.management.jmxremote in the command line, does Java pick a default port for remote JMX connections? Backstory: I am currently trying to develop a procedure to give to a customer that will enable them to connect to one of our processes via JMX from a remote machine. The goal is to facillitate their remote debugging of a situation occurring on a real-time display console. Because of their service level agreement, they are strongly motivated to capture as much data as possible and, if the situation looks too complicated to fix quickly, to restart the display console and allow it to reconnect to the server-side. I am aware the I could run jconsole on JDK 1.6 processes and jvisualvm on post-JDK 1.6.7 processes given physical access to the console. However, because of the operational requirements and people problems involved, we are strongly motivated to grab the data that we need remotely and get them up and running again. EDIT: I am aware of the command line port property com.sun.management.jmxremote.port=portNum The question that I am trying to answer is, if you do not set that property at the command line, does Java pick another port for remote monitoring? If so, how could you determine what it might be?

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• Java InputReader. Detect if file being read is binary?

  - by Trizicus

  I had posted a question in regards to this code. I found that JTextArea does not support the binary type data that is loaded. So my new question is how can I go about detecting the 'bad' file and canceling the file I/O and telling the user that they need to select a new file? class Open extends SwingWorker<Void, String> { File file; JTextArea jta; Open(File file, JTextArea jta) { this.file = file; this.jta = jta; } @Override protected Void doInBackground() throws Exception { BufferedReader br = null; try { br = new BufferedReader(new FileReader(file)); String line = br.readLine(); while(line != null) { publish(line); line = br.readLine(); } } finally { try { br.close(); } catch (IOException e) { } } return null; } @Override protected void process(List<String> chunks) { for(String s : chunks) jta.append(s + "\n"); } }

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• Modifying NSMutableDictionary from a single index format into nested (array within array)

  - by Michael Robinson

  I need to take the member ID off the top of this and create an array inside that contains the rest of the JSON return. Here is my JSON return. [{"F_Name_VC":"Frank", "L_Name_VC":"Johnson", "userid":"18", "age":"23", },] After it is json-deserialized it looks like this: I need convert it to be transformed into this, with children sub-array: Someone else posted a similar question but without the fact that it was coming from a JSON deserialization. There were two answers but no conclusion to the question. (Answer 1): NSDictionary *item1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@" member",[NSNumber numberWithInt:3],nil] forKeys:[NSArray arrayWithObjects:@"Title",@"View",nil]]; Answer (2): NSMutableArray *Rows = [NSMutableArray arrayWithCapacity: 1]; for (int i = 0; i < 4; ++i) { NSMutableArray *theChildren = [NSMutableArray arrayWithCapacity: 1]; [theChildren addObject: [NSString stringWithFormat: @"tester %d", i]]; NSString *aTitle = [NSString stringWithFormat: @"Item %d", i]; NSDictionary *anItem = [NSDictionary dictionaryWithObjectsAndKeys: aTitle, @"Title", theChildren, @"Children"]; [Rows addObject: anItem]; } NSDictionary *Root = [NSDictionary withObject: Rows andKey: @"Rows"]; Here is my JSON return and save code: NSData *jsonData = [jsonreturn dataUsingEncoding:NSUTF32BigEndianStringEncoding]; NSError *error = nil; NSDictionary * dict = [[CJSONDeserializer deserializer] deserializeAsDictionary:jsonData error:&error]; if (dict) { rowsArray = [dict objectForKey:@"member"]; [rowsArray retain]; } Thanks in advance. Every tutorial on JSON only shows a simple array being returned, never with children..It's driving me crazy trying to figure this out.

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• Drupal Views api, add simple argument handler

  - by LanguaFlash

  Background: I have a complex search form that stores the query and it's hash in a cache. Once the cache is set, I redirect to something like /searchresults/e6c86fadc7e4b7a2d068932efc9cc358 where that big long string on the end is the md5 hash of my query. I need to make a new argument for views to know what the hash is good for. The reason for all this hastle is because my original search form is way to complex and has way to many arguments to consider putting them all into the path and expecting to do the filtering with the normal views arguments. Now for my question. I have been reading views 2 documentation but not figuring out how to accomplish this custom argument. It doesn't seem to me like this should be as hard as it seems to me like it must be. Leaving aside any knowledge of the veiws api, it would seem that all I need is a callback function that will take the argument from the path as it's only argument and return a list of node id's to filter to. Can anyone point me to a solution or give me some example code? Thanks for your help! You guys are great. PS. I am pretty sure that my design is the best I can come up with, lets don't get off my question and into cross checking my design logic if we can help it.

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• Creating an API for an ASP.NET MVC site with rate-limiting and caching

  - by Maxim Z.

  Recently, I've been very interested in APIs, specifically in how to create them. For the purpose of this question, let's say that I have created an ASP.NET MVC site that has some data on it; I want to create an API for this site. I have multiple questions about this: What type of API should I create? I know that REST and oData APIs are very popular. What are the pros and cons of each, and how do I implement them? From what I understand so far, REST APIs with ASP.NET MVC would just be actions that return JSON instead of Views, and oData APIs are documented here. How do I handle writing? Reading from both API types is quite simple. However, writing is more complex. With the REST approach, I understand that I can use HTTP POST, but how do I implement authentication? Also, with oData, how does writing work in the first place? How do I implement basic rate-limiting and caching? From my past experience with APIs, these are very important things, so that the API server isn't overloaded. What's the best way to set these two things up? Can I get some sample code? Any code that relates to C# and ASP.NET MVC would be appreciated. Thanks in advance! While this is a broad question, I think it's not too broad... :) There are some similar questions to this one that are about APIs, but I haven't found any that directly address the questions I outlined here.

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• Eclipse and JavaFX? is it just me?

  - by jeff porter

  I'm looking at learning JavaFX. I've tried setting Eclipse to develop a small app and I've downloaded the Eclipse plugin. Eclipse JavaFX plugin BUT... it just seems, well, flakey. So I have 3 questions... 1: Is there a better plugin? 2: Or is there some great set of tutorials out there that I'm missing? 3: finally, is it meant to be easy to call Java code from FX? I'm stuggling, it there a good example somewhere? On questions 1 & 2, Eclipse underlines code in red that just shouln't be. For example.. see this image... Why does it underline bit of imports in red? I know this is little of an open ended question. So I guess my main question is this... Is my experiance of JavaFX and Eclipse the best I can hope for? Or am I missing something ? (and I'm not looking for a Yes/No response) :-) Just looking for a discussion on how best to learn/develop JavaFx.

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• echo POST array.. or other ideas?

  - by gamerzfuse

  Update: As seen in the Original Questions below, I am looking to echo an array. The problem is that when I send the Moneris gateway to return a POST array to my new file (cart.php) it gets a 500 Internal Server Error. This is the same error I received when it send to the script, which should have worked. Is there any reason that it would always send a 500 Internal Server Error? Cart.php Direct Link Craig ORIGINAL QUESTION: Hello there, I am back for another question. Here is my dilemma: I have a script (ImageFolio Commerce) that hasn't been updated on our server since.. probably 2003. The script had a Payment Gateway (Moneris) manually added to it by the company who offers the script. This costs $1000 to get them to add a gateway. I now have a new client who purchased this business from the previous owner. While switching the account to the new owner's Moneris account, we found out that things have been updated. Long story short.. The Moneris gateway can send 3 types of responses: POST with XML Data POST GET I imagine it is easiest to just use the POST array. I have the file that it sends the response to. As of now the file responds with a Internal Server error, but it does process the order. What I want to do is determine what the POST array is that is being sent, so that I can take it and echo it in a logical manner. Is there a way to capture and echo the entire POST? Or can someone suggest a better method of doing this? Thank you, Craig

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• magento payment process.. how it works in general

  - by spirytus

  hi everyone, got a question and I hope this is right place to ask :).. don’t quite understand how payment works in magento. client goes to checkout and lets say wants to pay as a guest, so provides address etc. and finally gets to payment methods. Then I want clients to pay thru credit card. Already have module installed for gateway (bank?) of my choice. At that point I would expect users to be redirected to 3rd party page (bank hosted) where they giving all the details, only after being returned to my magento site with appropriate message. In magento however it seems like they need to provide cc numbers and details on magento checkout page. I don’t understand if I (or the payment module I installed) need to transfer then all the credit card details to bank? I would have to have checkout page on ssl connection and static ip right? The thing is I want to avoid touching CC numbers at any point and would love to have it done by a bank page. I like the idea of magento interface all the way without redirecting to another page though, the only problem is not sure if would be able to set it all up properly. If anyone could explain to me possible options, what is the common way to do it and how the whole process works that would be very much appreciated. I did my research and looked all over google and various forums still need someones help though. Please let me know if some parts of my question are not quite clear, will try to better explain if necessary.

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• Pronunciation of programming structures (particularly in c#)

  - by Andrzej Nosal

  As a non-English speaking person I often have problems pronouncing certain programming structures and abbreviations. I've been watching some video tutorials and listening to podcasts as well, though I couldn't catch them all. My question is what is the common or correct pronunciation of the following code snippets? Generics, like IEnumerable<int> or in a method void Swap<T>(T lhs, T rhs) Collections indexing and indexer access e.g. garage[i], rectangular arrays myArray[2,1] or jagged[1][2][3] Lambda operator =>, e.g. in a where extension method .Where(animal => animal.Color == Color.Brown) or in an anonymous method () => { return false;} Inheritance class Derived : Base (extends?) class SomeClass : IDisposable (implements?) Arithemtic operators += -= *= /= %= ! Are += and -= pronounced the same for events? Collections initializers new int[] { 4, 5, 8, 9, 12, 13, 16, 17 }; Casting MyEnum foo = (MyEnum)(int)yourFloat; (as?) Nullables DateTime? dt = new DateTime?(); I tagged the question with C# as some of them are specific to C# only.

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• Conversion type

  - by Ruben

  Hi, I've got the following question. I've got one class "Instellingen" that's a property in 3 other classes public class Instellingen { private int _ID; } public class Class1: Label { private Instellingen _Instellingen; } public class Class2 : Label { private Instellingen _Instellingen; } public class Class3 : Label { private Instellingen _Instellingen; } If I've got another class, that uses the other classes (but it can be anyone of this 3 classes) Do i have to use a switch? or is there an easier way? public class AnotherClass { public AnotherClass () { GetInstellingenFromClass(new Class1()); GetInstellingenFromClass(new Class2()); GetInstellingenFromClass(new Class3()); } private void GetInstellingenFromClass(Control c) { switch (c.GetType.ToString()) { case "Class1": Class1 klasse = (Class1) c; //Do something with the _Instellingen of this class break; case "Class2": Class2 klasse2 = (Class2) c; //Do something with the _Instellingen of this class break; case "Class3": Class3 klasse3 = (Class3)c; //Do something with the _Instellingen of this class break; } } } (does there exists something so i can just do something like c._Instellingen -- without converting it first to the right type, where it doesn't matter what type c is?) I hope you understand my question. Thanks

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• Use AJAX to reload captcha

  - by arik-so

  Hello! This question may have been asked already - but unfortunately, I could not find any satisfactory answers. I will just ask it for my concrete case and ask the admins not to delete the question for at least a few days so I can try it out... I have a page. It uses a captcha. Like so: <?php session_start(); // the captcha saves the md5 into the session ?> <img src="captcha.php" onclick="this.src = this.src" /> That was my first code. It did not work, because the browser condsidered it useless to reload an image if the source is the same. My current solution is to pass a get parameter: onclick="this.src = 'captcha.php?randomNumber='+ranNum" The JavaScript variable var ranNum is generated randomly every time the onclick event fires. It works fine, still, I don't like the possibility, if the - though improbable - case of two numbers being the same twice in a row. Although the random number varies between -50,000 and 50,000 - I still do not like it. And I don't think the method is right. I would like to know the 'righter' method, by means of AJAX. I know it's possible. I hope you know how it's possible ^^ In that case, please show me. Thanks in advance! By the way - if I spell cap(t)cha differently, never mind, the reference to the PHP file is right in my code: I use randomImage.php

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• Multi-level shop, xml or sql. best practice?

  - by danrichardson

  Hello, i have a general "best practice" question regarding building a multi-level shop, which i hope doesn't get marked down/deleted as i personally think it's quite a good "subjective" question. I am a developer in charge (in most part) of maintaining and evolving a cms system and associated front-end functionality. Over the past half year i have developed a multiple level shop system so that an infinite level of categories may exist down into a product level and all works fine. However over the last week or so i have questioned by own methods in front-end development and the best way to show the multi-level data structure. I currently use a sql server database (2000) and pull out all the shop levels and then process them into an enumerable typed list with child enumerable typed lists, so that all levels are sorted. This in my head seems quite process heavy, but we're not talking about thousands of rows, generally only 1-500 rows maybe. I have been toying with the idea recently of storing the structure in an XML document (as well as the database) and then sending last modified headers when serving/requesting the document for, which would then be processed as/when nessecary with an xsl(t) document - which would be processed server side. This is quite a handy, reusable method of storing the data but does it have more overheads in the fact im opening and closing files? And also the xml will require a bit of processing to pull out blocks of xml if for instance i wanted to show two level mid way through the tree for a side menu. I use the above method for sitemap purposes so there is currently already code i have built which does what i require, but unsure what the best process is to go about. Maybe a hybrid method which pulls out the data, sorts it and then makes an xml document/stream (XDocument/XmlDocument) for xsl processing is a good way? - This is the way i currently make the cms work for the shop. So really (and thanks for sticking with me on this), i am just wandering which methods other people use or recommend as being the best/most logical way of doing things. Thanks Dan

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• Java: Implement own message queue (threadsafe)

  - by derMax

  The task is to implement my own messagequeue that is thread safe. My approach: public class MessageQueue { /** * Number of strings (messages) that can be stored in the queue. */ private int capacity; /** * The queue itself, all incoming messages are stored in here. */ private Vector<String> queue = new Vector<String>(capacity); /** * Constructor, initializes the queue. * * @param capacity The number of messages allowed in the queue. */ public MessageQueue(int capacity) { this.capacity = capacity; } /** * Adds a new message to the queue. If the queue is full, it waits until a message is released. * * @param message */ public synchronized void send(String message) { //TODO check } /** * Receives a new message and removes it from the queue. * * @return */ public synchronized String receive() { //TODO check return "0"; } } If the queue is empty and I call remove(), I want to call wait() so that another thread can use the send() method. Respectively, I have to call notifyAll() after every iteration. Question: Is that possible? I mean does it work that when I say wait() in one method of an object, that I can then execute another method of the same object? And another question: Does that seem to be clever?

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• Grouping a list of of entities which has a sublist in c#

  - by mikei

  I have a set of Entities which basically has this structure. {Stats Name="<Product name> (en)" TotalResources="10" ..} {DayStats Date="2009-12-10" TotalResources="5"} {DayStats Date="2009-12-11" TotalResources="5"} {Stats} {Stats Name="<Product name> (us)" TotalResources="10" ..} {DayStats Date="2009-12-10" TotalResources="5"} {DayStats Date="2009-12-11" TotalResources="5"} {Stats} ... What I wan't to extract from this set is a new set entities (or entity in the example above) where the first level has been grouped by the (ignoring the country label) where all/some of the properties has been summmed together, including the the sublist of {DayStas} on a per day basis. So the result set of the example would look something like this: {Stats Name="<Product name>" TotalResources="20" ..} {DayStats Date="2009-12-10" TotalResources="10"} {DayStats Date="2009-12-11" TotalResources="10"} {Stats} ... So my question is: Is it possible to do this in a more elegant way in LINQ rather than the vanilla "loop-trhough-each-entity-and-compare"-way? And I wan't the set to contain the same type of entities as the original set ({Stats}, {DayStats}), your answer doesn't need to include code for that, I can probably work that out by myself. Just letting you know incase you need to take that into account. (I'm sorry if this question has been discussed before, I tried searching to no avail. I guess my searching skills are fuubar ;)) Merry christmas =)

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• Why is creating a ring buffer shared by different processes so hard (in C++), what I am doing wrong?

  - by recipriversexclusion

  I am being especially dense about this but it seems I'm missing an important, basic point or something, since what I want to do should be common: I need to create a fixed-size ring buffer object from a manager process (Process M). This object has write() and read() methods to write/read from the buffer. The read/write methods will be called by independent processes (Process R and W) I have implemented the buffer, SharedBuffer<T&>, it allocates buffer slots in SHM using boost::interprocess and works perfectly within a single process. I have read the answers to this question and that one on SO, as well as asked my own, but I'm still in the dark about how to have different processes access methods from a common object. The Boost doc has an example of creating a vector in SHM, which is very similar to what I want, but I want to instantiate my own class. My current options are: Use placement new, as suggested by Charles B. to my question; however, he cautions that it's not a good idea to put non-POD objects in SHM. But my class needs the read/write methods, how can I handle those? Add an allocator to my class definition, e.g. have SharedBuffer<T&, Alloc> and proceed similarly to the vector example given in boost. This sounds really complicated. Change SharedBuffer to a POD class, i.e. get rid of all the methods. But then how to synchronize reading and writing between processes? What am I missing? Fixed-length ring buffers are very common, so either this problem has a solution or else I'm doing something wrong.

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• Raising C# events with an extension method - is it bad?

  - by Kyralessa

  We're all familiar with the horror that is C# event declaration. To ensure thread-safety, the standard is to write something like this: public event EventHandler SomethingHappened; protected virtual void OnSomethingHappened(EventArgs e) { var handler = SomethingHappened; if (handler != null) handler(this, e); } Recently in some other question on this board (which I can't find now), someone pointed out that extension methods could be used nicely in this scenario. Here's one way to do it: static public class EventExtensions { static public void RaiseEvent(this EventHandler @event, object sender, EventArgs e) { var handler = @event; if (handler != null) handler(sender, e); } static public void RaiseEvent<T>(this EventHandler<T> @event, object sender, T e) where T : EventArgs { var handler = @event; if (handler != null) handler(sender, e); } } With these extension methods in place, all you need to declare and raise an event is something like this: public event EventHandler SomethingHappened; void SomeMethod() { this.SomethingHappened.RaiseEvent(this, EventArgs.Empty); } My question: Is this a good idea? Are we missing anything by not having the standard On method? (One thing I notice is that it doesn't work with events that have explicit add/remove code.)

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• Write a sql for updating data based on time

  - by Lu Lu

  Hello everyone, Because I am new with SQL Server and T-SQL, so I will need your help. I have 2 table: Realtime and EOD. To understand my question, I give example data for 2 tables: ---Realtime table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 // this day is not existed in EOD -> inserting BBC 1/3/2009 03:05:01 458 // this day is not existed in EOD -> inserting ABC 1/2/2009 03:05:01 326 // this day is new -> updating BBC 1/2/2009 03:05:01 454 // this day is new -> updating ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 ABC 1/2/2009 01:05:01 313 BBC 1/2/2009 01:05:01 423 ---EOD table--- Symbol Date Value ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 I will need to create a store procedure to update value of symbols. If data in day of a symbol is new (compare between Realtime & EOD), it will update value and date for EOD at that day if existing, otherwise inserting. And store will update EOD table with new data: ---EOD table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 BBC 1/3/2009 03:05:01 458 ABC 1/2/2009 03:05:01 326 BBC 1/2/2009 03:05:01 454 P/S: I use SQL Server 2005. And I have a similar answered question at here: http://stackoverflow.com/questions/2726369/help-to-the-way-to-write-a-query-for-the-requirement Please help me. Thanks.

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