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• Windows 8 "Upgrade Offer" eligibilty when running the Consumer Preview in a VM?

  - by Dan Harris

  If I have a VM running Windows 8 Consumer/Release Preview, am I allowed to take advantage of the Windows 8 upgrade offer, and install it on that machine? I would have assumed not...as there was never a licensed version of XP SP3 through to Windows 7 installed in that VM. It was a clean installation of the Consumer Preview into a VM. My confusion comes from the notes at the bottom of the download page for the Upgrade offer which states: Offer valid from October 26, 2012 until January 31, 2013 and is for individuals and small businesses needing to upgrade up to five devices. If you are a business customer looking to upgrade more than five devices to Windows 8 Pro, contact your Microsoft partner for more information. To install Windows 8 Pro, customers must be running Windows XP SP3, Windows Vista, Windows 7, Windows 8 Consumer Preview, or Windows 8 Release Preview. I am assuming it's not possible and i'll need to purchase the System Builder edition to install within a VM? My guess is that you can use your downloaded upgrade offer only if you updated Windows 7 to the release preview, and therefore had the Windows 7 license on the machine, I used the serial number from the Microsoft Website when downloading the Release Preview, and did a clean install, so there was never a Windows 7 license on the VM. I have MSDN for development purposes, but I am looking to run in a VM for personal use as well, so my MSDN license is not valid for that particular use.

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• Why would using a Temp table be faster than a nested query?

  - by Mongus Pong

  We are trying to optimise some of our queries. One query is doing the following: SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, INTO [#Gadget] FROM task t SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) as Client FROM [#Gadget] order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC DROP TABLE [#Gadget] (I have removed the complex subquery, cos I dont think its relevant other than to explain why this query has been done as a two stage process.) Now I would have thought it would be far more efficient to merge this down into a single query using subqueries as : SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) FROM ( SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, FROM task t ) as sub order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC This would give the optimiser better information to work out what was going on and avoid any temporary tables. It should be faster. But it turns out it is a lot slower. 8 seconds vs under 5 seconds. I cant work out why this would be the case as all my knowledge of databases imply that subqueries would always be faster than using temporary tables. Can anyone explain what could be going on!?!?

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• C# expression tree for ordinary code

  - by rwallace

  It's possible to create an expression tree, if you declare it as such. But is it possible to get an expression tree for an ordinary chunk of code such as a method or property getter? What I'm trying to do is, let's say for an order processing system, I have a class for order items: class Item : Entity { [Cascade] public Document document { get; set; } public int line { get; set; } public Product product { get; set; } public string description { get; set; } public decimal qty { get; set; } public decimal price { get; set; } public decimal net { get { return qty * price; } } public VatCode vat_code { get; set; } } where the net value equals qty * price, so I'd like to declare it as such, either with a property or method, and then also have the framework introspect that expression so it can generate appropriate SQL for defining a corresponding calculated column in a corresponding database view. The most obvious way to do this would be to get the expression tree for a property getter or a method, but I can't find any indication how to do this, or that it is possible. (I have found a way to get a method body as a byte stream, but that's not what's desired here.) If that isn't possible, I suppose the recommended solution would be to declare something like a static field that is an expression tree, and compile/run it at run time for internal use, and also introspect as normal for SQL generation?

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• Cannot use a Like query in a JSP prepared statement?

  - by SeerUK

  OK, first the query code and query: ps = conn.prepareStatement("select instance_id, ? from eam_measurement where resource_id in (select RESOURCE_ID from eam_res_grp_res_map where resource_group_id = ?) and DSN like '?' order by 2"); ps.setString(1,"SUBSTR(DSN,27,16)"); ps.setInt(2,defaultWasGroup); ps.setString(3,"%Module=jvmRuntimeModule:freeMemory%"); rs = ps.executeQuery(); while (rs.next()) { bla blah blah blah ... Returns an empty resultSet. Through basic debugging I have found its the 3rd bind that is the problem i.e. DSN like '?' I have tried all kinds of variations, the most sensible of which seemed to be using: DSN like concat('%',?,'%') bit that doesn' work as I am missing the ' ' either side of the concatenated string so I try DSN like ' concat('%',Module=P_STAG_JDBC01:poolSize,'%') ' order by 2 but I just can't seem to find a way to get them in that works. What am I missing? :) Thanks!

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• Using C# to parse a SOAP Response

  - by Gavin

  I am trying to get the values for faultcode, faultstring, and OrderNumber from the SOAP below <SOAP:Envelope xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/"> <SOAP:Body> <faultcode>1234</faultcode> <faultstring>SaveOrder:SetrsOrderMain:Cannot change OrderDate if GLPeriod is closed, new OrderDate is 3/2/2010:Ln:1053</faultstring> <detail> <SOAP:Envelope xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/"> <SOAP:Body UserGUID="test"> <m:SaveOrder xmlns:m="http://www.test.com/software/schema/" UserGUID="test"> <Order OrderNumber="1234-1234-123" Caller="" OrderStatus="A" xmlns="http://www.test.com/software/schema/"> Here is my code in C# XDocument doc = XDocument.Load(HttpContext.Current.Server.MapPath("XMLexample.xml")); var errorDetail = new EcourierErrorDetail { FaultCode = from fc in doc.Descendants("faultcode") select fc.Value, FaultString = from fs in c.Descendants("faultstring") select fs.Value, OrderNumber = from o in doc.Descendants("detail").Elements("Order").Attributes("OrderNumber") select o.Value }; return errorDetail; I am able to get the values for both faultcode and faultstring but not the OrderNumber. I am getting "Enumeration yielded no results." Can anyone help? Thanks.

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• How do I write escape characters verbatim (without escaping) using StreamWriter?

  - by Joel

  I'm writing a utility that takes in a .resx file and creates a javascript object containing properties for all the name/value pairs in the .resx file. This is all well and good, until one of the values in the .resx is This dealer accepts electronic orders. /r/nClick to order {0} from this dealer. I'm adding the name/value pairs to the js object like this: streamWriter.Write(string.Format("\n{0} : \"{1}\"", kvp.Key, kvp.Value)); When kvp.Value = "This dealer accepts electronic orders./r/nClick to order {0} from this dealer." This causes StreamWriter.Write() to actually place a newline in between 'orders.' and 'Click', which naturally screws up my javascript output. I've tried different things with @ and without using string.Format, but I've had no luck. Any suggestions? Edit: This application is run during build to get some javascript files deployed later, so at no point is it accessible to / run by anyone but the app developers. So while I obviously need a way to escape characters here, XSS as such is not really a concern.

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• On counting pairs of words that differ by one letter

  - by Quintofron

  Let us consider n words, each of length k. Those words consist of letters over an alphabet (whose cardinality is n) with defined order. The task is to derive an O(nk) algorithm to count the number of pairs of words that differ by one position (no matter which one exactly, as long as it's only a single position). For instance, in the following set of words (n = 5, k = 4): abcd, abdd, adcb, adcd, aecd there are 5 such pairs: (abcd, abdd), (abcd, adcd), (abcd, aecd), (adcb, adcd), (adcd, aecd). So far I've managed to find an algorithm that solves a slightly easier problem: counting the number of pairs of words that differ by one GIVEN position (i-th). In order to do this I swap the letter at the ith position with the last letter within each word, perform a Radix sort (ignoring the last position in each word - formerly the ith position), linearly detect words whose letters at the first 1 to k-1 positions are the same, eventually count the number of occurrences of each letter at the last (originally ith) position within each set of duplicates and calculate the desired pairs (the last part is simple). However, the algorithm above doesn't seem to be applicable to the main problem (under the O(nk) constraint) - at least not without some modifications. Any idea how to solve this?

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• 3D and AI basics. The foundation before the coding.

  - by Allan

  Hi, everyone. (If you have the time and patience:) I've recently made the decision to study programming seriously and I'm about to order TAOCP and Concrete Mathematics to begin my studies (please don't get caught up on this). I'm very much interested in learning and understanding how 3D works but I'm aware that if I plan to do it right there's still a long walk before I get to actually play with 3D coding. Now to the question.. (tl;dr) Excluding programming itself, what disciplines do I have to be familiar with to code 3D? What kinds of mathematics? Physics? What else? What books do you recommend on such subjects? Now read it all again but replacing "3D" with "AI". Please don't recommend computer-specific books. The question is about the foundation to be learned before using the machine. Also, if possible, please keep the list brief; I plan to order one book on each subject but no more than that for now. Excuse me for any English mistakes, it's not my first language. Thank you.

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• Magento: The best way to hook into the checkout process

  - by dan.codes

  I am integrating with a third party order management system and I have to make calls to it throughout the checkout process. The problem is, I don't think there are many events available because of how the onepage checkout is all done in javascript/ajax calls. There are a few like after saving the shipping method, and none of the dynamic events seem to fit either. basically I need to know as soon as the user is getting access to the shipping method tab to pass the billing shipping address over, then after the shipping method, to pass that over. Obviously there is an event for that. I know there are ones for when you submit an order so that should be good. I guess I only need to know when the billing/shipping address is saved. I was using controller_action_layout_render_before_checkout_onepage_progress but the progress gets called way to late. It just doesn't seem like there are a lot of hooks through the onepage checkout. if anyone can give me some examples of what they have done that would be great!

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• Moving from 1 Linux Partition to Many over USB Mount

  - by Mistiry

  We have devices which use Compact Flash for storage. They work OK, but we recently got industrial-grade CF cards to start using. One of the major problems we get is corruption on the flash card. As it is now, these flash cards run Debian with everything in a single partition. We want to have multiple partitions on the new industrial CF cards to help avoid some of the corruption problems. I booted up the device, and attached a USB CF reader. I then used fdisk to partition the CF card in the USB reader. How can I move the data to these partitions so that it works? I have a partition for each of these directories: /lib /var /root /boot /tmp /home /etc / swap space I imagine I can't just use rsync - do I need to attach a second CF reader with a copy of the CF card, so that it's not active and in-use - and then copy from the first reader to the second? How will the system know where to find its files? I know I'd have to change fstab, but that resides in /etc, which will be on a separate partition...how will it find the fstab file if it can't find /etc? And what about grub? I'm at a loss, perhaps its just because I'm under the weather, or I'm just missing a piece of logic here... Any help is greatly appreciated, this is somewhat urgent as our existing stock is nearing its end and we don't want to purchase anything but these industrial cards, but need to get it working with partitions.

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• iPhone - sorting the results of a core data entity

  - by Digital Robot

  I have a core data entity that represents the attributes of a product, as number, price, etc. The product number is a NSString property and follows the form X.y where X is a number variable of digits and Y is one digit. For example. 132.2, 99.4, etc. I am querying the database to obtain the list of product numbers in order: The code is like this: + (NSArray*)todosOsItens:(NSString *)pName inManagedObjectContext:(NSManagedObjectContext *)context { Product *aProduct = [Product productWithName:pName inManagedObjectContext:context]; NSArray *all = nil; NSFetchRequest *request = [[NSFetchRequest alloc] init]; request.entity = [NSEntityDescription entityForName:@"Attributes" inManagedObjectContext:context]; request.predicate = [NSPredicate predicateWithFormat: @"(belongsTo == %@)", aProduct]; [request setResultType:NSDictionaryResultType]; [request setReturnsDistinctResults:YES]; [request setPropertiesToFetch:[NSArray arrayWithObject:item]]; NSSortDescriptor *sortByItem = [NSSortDescriptor sortDescriptorWithKey:@"ProductNumber" ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObject:sortByItem]; [request setSortDescriptors:sortDescriptors]; NSError *error = nil; all = [[context executeFetchRequest:request error:&error] mutableCopy]; [request release]; return all; } but this query is not returning the sorted results. The results are coming on their natural order on the database. How do I do that? thanks.

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• Hibernate NamingStrategy implementation that maintains state between calls

  - by Robert Petermeier

  Hi, I'm working on a project where we use Hibernate and JBoss 5.1. We need our entity classes to be mapped to Oracle tables that follow a certain naming convention. I'd like to avoid having to specify each table and column name in annotations. Therefore, I'm currently considering implementing a custom implementation of org.hibernate.cfg.NamingStrategy. The SQL naming conventions require the name of columns to have a suffix that is equivalent to a prefix of the table name. If there is a table "T100_RESOURCE", the ID column would have to be named "RES_ID_T100". In order to implement this in a NamingStrategy, the implementation would have to maintain state, i.e. the current class name it is creating the mappings for. It would rely on Hibernate to always call classToTableName() before propertyToColumnName() and to determine all column names by calling propertyToColumnName() before the next call to classToTableName() Is it safe to do that or are there situations where Hibernate will mix things up? I am not thinking of problems through multiple threads here (which can be solved by keeping the last class name in a ThreadLocal) but also of Hibernate deliberately calling this out of order in certain circumstances. For example Hibernate asking for mappings of three properties of class A, then one of class B, then again more attributes of class A.

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• ruby on rails implement search with auto complete

  - by user429400

  I've implemented a search box that searches the "Illnesses" table and the "symptoms" table in my DB. Now I want to add auto-complete to the search box. I've created a new controller called "auto_complete_controller" which returns the auto complete data. I'm just not sure how to combine the search functionality and the auto complete functionality: I want the "index" action in my search controller to return the search results, and the "index" action in my auto_complete controller to return the auto_complete data. Please guide me how to fix my html syntax and what to write in the js.coffee file. I'm using rails 3.x with the jquery UI for auto-complete, I prefer a server side solution, and this is my current code: main_page/index.html.erb: <p> <b>Syptoms / Illnesses</b> <%= form_tag search_path, :method => 'get' do %> <p> <%= text_field_tag :search, params[:search] %> <br/> <%= submit_tag "Search", :name => nil %> </p> <% end %> </p> auto_complete_controller.rb: class AutoCompleteController < ApplicationController def index @results = Illness.order(:name).where("name like ?", "%#{params[:term]}%") + Symptom.order(:name).where("name like ?", "%#{params[:term]}%") render json: @results.map(&:name) end end search_controller.rb: class SearchController < ApplicationController def index @results = Illness.search(params[:search]) + Symptom.search(params[:search]) respond_to do |format| format.html # index.html.erb format.json { render json: @results } end end end Thanks, Li

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• Wordpress Query Compare operator not working?

  - by Liam

  I have the following wordpress query... $args = array('orderby' => 'meta_value_num', 'meta_key' => 'order', 'order' => 'ASC', 'meta_query' => array( array( 'key' => $customkey, 'value' => $customvalue, 'compare' => '=' ), array( 'key' => $customkey1, 'value' => $customvalue1, 'compare' => '=' ), array( 'key' => 'coverageRegion', 'value' => 'national', 'compare' => '=' ), array( 'key' => 'vehicleType', 'value' => 'psv', 'compare' => '!=' ) ) ); I want to return posts where there custom field 'Vechicle Type' is not PSV, The above however returns posts with exactly that, has anybody come across this before? Seems im not the only one neither... http://wordpress.org/support/topic/meta_query-without-key-results-in-compare-of-not-like-not-working

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• jQuery prevAll displaying text in backward ordering

  - by SoulieBaby

  hi all, I'm trying to use jQuery to get all the paragraphs before the first h2 tag in my content. Here's the code I'm using: $(".content").find("h2:first").prevAll().text() Which is grabbing the content, although it's displaying it in backwards order. Example content: <div class="content"> <p>paragraph 1</p> <p>paragraph 2</p> <p>paragraph 3</p> <h2>First h2 tag</h2> <p>paragraph 4</p> <p>paragraph 5</p> <p>paragraph 6</p> <h2>Second h2 tag</h2> </div> The above code is outputting: <p>paragraph 3</p> <p>paragraph 2</p> <p>paragraph 1</p> Is there any way of reversing this, so it's in the correct order? I have tried using nextAll using different codes, but it seems to grab all of my content, or not work at all lol

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• data ownership and performance

  - by Ami

  We're designing a new application and we ran into some architectural question when thinking about data ownership. we broke down the system into components, for example Customer and Order. each of this component/module is responsible for a specific business domain, i.e. Customer deals with CRUD of customers and business process centered around customers (Register a n new customer, block customer account, etc.). each module is the owner of a set of database tables, and only that module may access them. if another module needs data that is owned by another module, it retrieves it by requesting it from that module. so far so good, the question is how to deal with scenarios such as a report that needs to show all the customers and for each customer all his orders? in such a case we need to get all the customers from the Customer module, iterate over them and for each one get all the data from the Order module. performance won't be good...obviously it would be much better to have a stored proc join customers table and orders table, but that would also mean direct access to the data that is owned by another module, creating coupling and dependencies that we wish to avoid. this is a simplified example, we're dealing with an enterprise application with a lot of business entities and relationships, and my goal is to keep it clean and as loosely coupled as possible. I foresee in the future many changes to the data scheme, and possibly splitting the system into several completely separate systems. I wish to have a design that would allow this to be done in a relatively easy way. Thanks!

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• What tools do you have at your disposal as a manager to promote a way of thinking

  - by John Leidegren

  This question goes beoynd just programming, but I'd like to get some input on this, if that's okay with the community. Preferably from people that do a lot of coding themselves but also manage other people coding. My problem is this. We have all these ideas that we know is good for the overall strategy of the company and the problem is not figuring out what to do, it's to come about this change. Just telling someone to do things differently isn't enough and it's hard to promote a mind set that is shared within all of the company, (this will take time). If I could jump forward I'd like it if we could create a very nurturing company culture that promotes these ideals cross all areas but I'm not sure what tools to use. And by tools I mean anything I'm legally permitted to do. e.g. we could talk about, we could arrange traning sessions, we could spend more time in meeting (talk about it more), we could spend more time designing, we could spend more time pair-programming, we could add/remove incentive or we could encurage more play. Ultimately if we did all of these things what will be the recurring theme that ties this together. I'd like to be able to answer the question -- why should we do things like this? -- and come up with an answer that explains how important it is to think about our ideals from begining to end. I've puposly avoided to talk about or specifics of the situtation becuase I believe that it narrows things down too much. But I guess, by know you either know how to answer this question or you're as confused as I am ;) I'd love to hear from people who had to bring about a change in order to go from chaos to order, or fix something in the organization which wasn't working. And I'd like to hear it from the perspective of the developer and designer. -- or -- You could simply weigh in on what are the most important qualities in an organization encurage or stimulate rigid fun development cycle from start to finish?

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• Information on the BMPP File Extension/Format

  - by Angel Brighteyes

  I am looking for information on the file type BMPp. Namely I need an application that can create this file type, preferably open source or free. Wikipedia says for BMP File Format that 'BMPp' is a "type code", which is the "mechanism used by pre-OSX Macs ... to denote a files format..." (Look in the little info-box of general information under "Type code"). Continuing my research, I found an old 2009 archived mailing list "Re: Incorrect png file type 'PNG' that talks about something related to another problem a developer is having. In the response he talks about there being variant file types, and lists BMPp as being linked to an old version of Graphics Converter. The company Lemkesoft sells Graphics Converter, which I am not willing to purchase. I can't imagine that the only program in existence to make a BMPp file is that program. There has got to be another way to make that file type, other than creating a BMP file and just renaming it to BMPp (unless of course it is really that easy)? This is the first time I've run into this file format, and it took a bit on Google, Bing, and Wikipedia to find the information that I've posted here. Any further help would be appreciated.

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• Datastructure choices for highspeed and memory efficient detection of duplicate of strings

  - by Jonathan Holland

  I have a interesting problem that could be solved in a number of ways: I have a function that takes in a string. If this function has never seen this string before, it needs to perform some processing. If the function has seen the string before, it needs to skip processing. After a specified amount of time, the function should accept duplicate strings. This function may be called thousands of time per second, and the string data may be very large. This is a highly abstracted explanation of the real application, just trying to get down to the core concept for the purpose of the question. The function will need to store state in order to detect duplicates. It also will need to store an associated timestamp in order to expire duplicates. It does NOT need to store the strings, a unique hash of the string would be fine, providing there is no false positives due to collisions (Use a perfect hash?), and the hash function was performant enough. The naive implementation would be simply (in C#): Dictionary<String,DateTime> though in the interest of lowering memory footprint and potentially increasing performance I'm evaluating a custom data structures to handle this instead of a basic hashtable. So, given these constraints, what would you use? EDIT, some additional information that might change proposed implementations: 99% of the strings will not be duplicates. Almost all of the duplicates will arrive back to back, or nearly sequentially. In the real world, the function will be called from multiple worker threads, so state management will need to be synchronized.

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• MySQL error code:1329 in function

  - by Sharad Sharma

  DELIMITER // CREATE DEFINER=`root`@`localhost` FUNCTION `formatMovieNames`(lID int) RETURNS varchar(1000) CHARSET latin1 BEGIN DECLARE output varchar(1000); DECLARE done INT DEFAULT 0; declare a varchar(200); declare cur1 cursor for select fileName from swlp4_movie where movieID in (select movieID from lesson_movie_map where lessonID = lID order by lm_map_id); DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; open cur1; read_loop: loop fetch cur1 into a; if done = 1 then leave read_loop; end if; set output = concat(output, 'movie:[',a,']<br/>'); set output = substr(output, 0, length(@output)-5); end loop; close cur1; RETURN output; END// I have create this function and when I run it I do not get any output (select fileName from swlp4_movie where movieID in (select movieID from lesson_movie_map where lessonID = 24 order by lm_map_id)); brings correct result I am trying to get result as movie:['movieName']< br / movie:['movieName1'] and so on (had to change br tag, cause it was adding a line break) cant't figure out what I am doing wrong

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• IPtables and Remote Desktop with Proxy

  - by Sebastian

  So I setup a windows 2008 web server R2 on VirtualBox. Currently using Bridged Network. I can remote desktop to the machine hosting the VM (10.0.0.183) but cannot remote desktop to the VM itself (10.0.0.195). The remote port on the VM set to 5003. VM setup to accept remote connections (windows side). We also use a proxy for our internet, and I added these rules under NAT. (centOS 5) on our proxy box. -A INPUT -p tcp --dport 3389 -j ACCEPT -A REROUTING -i ppp0 -p tcp --dport 3389 -j REDIRECT --to-port 5003 -A FORWARD -d 10.0.0.195 --dport 5003 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT I've been trying for hours and hours and just cannot get it to work. I also used freedns so that we can use a domain name to connect too this VM over the internet. (the DNS points to our external IP address). If we don't get this right we will have to purchase a PPoE from an ISP to connect to this VM remotely, but I know that there is an alternative route if I can just get this port forwarding right!

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• sort elements in jQuery object

  - by Fresheyeball

  <div class="myClass">1</div> <div class="myClass">2</div> <div class="myClass">3</div> <div class="myClass">4</div> <div class="myClass">5</div> <div class="myClass">6</div> var $myClass = $('.myClass'); $myClass.eq(0).text() //returns '1' $myClass.eq(4).text() //returns '5' $myClass.eq(5).text() //returns '6' What I want to do is reorder the objects in jQuery manually. //fantasy command reversing $myClass.eqSorter([5,4,3,2,1,0]); $myClass.eq(0).text() //returns '6' $myClass.eq(5).text() //returns '1' What I really want is to allow a fully custom order input //fantasy command custom ordering $myClass.eqSorter([3,5,4,2,0,1]); $myClass.eq(0).text() //returns '4' $myClass.eq(5).text() //returns '2' Now I've looked at basic ways of doing this like .sort as a part of javascript, but .sort takes a dynamic argument the compares things, and does not allow for a fully custom order. I also looked at making a new blank jquery object that I could pass elements into like this $newObjectVar.eq(0) = $myClass.eq(3); for example. But as of yet I have not found a way to make a blank jQuery object like this.

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• Efficient mapping of game entity positions in Java

  - by byte

  In Java (Swing), say I've got a 2D game where I have various types of entities on the screen, such as a player, bad guys, powerups, etc. When the player moves across the screen, in order to do efficient checking of what is in the immediate vicinity of the player, I would think I'd want indexed access to the things that are near the character based on their position. For example, if player 'P' steps onto element 'E' in the following example... | | | | | | | | | |P| | | | |E| | | | | | | | | ... would be to do something like: if(player.getPosition().x == entity.getPosition().x && entity.getPosition.y == thing.getPosition().y) { //do something } And thats fine, but that implies that the entities hold their positions, and therefor if I had MANY entities on the screen I would have to loop through all possible entities available and check each ones position against the player position. This seems really inefficient especially if you start getting tons of entities. So, I would suspect I'd want some sort of map like Map<Point, Entity> map = new HashMap<Point, Entity>(); And store my point information there, so that I could access these entities in constant time. The only problem with that approach is that, if I want to move an entity to a different point on the screen, I'd have to search through the values of the HashMap for the entity I want to move (inefficient since I dont know its Point position ahead of time), and then once I've found it remove it from the HashMap, and re-insert it with the new position information. Any suggestions or advice on what sort of data structure / storage format I ought to be using here in order to have efficient access to Entities based on their position, as well as Position's based on the Entity?

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• DB optimization to use it as a queue

  - by anony

  We have a table called worktable which has some columns(key(primary key), ptime, aname, status, content) we have something called producer which puts in rows in this table and we have consumer which does an order-by on the key column and fetches the first row which has status as 'pending'. The consumer does some processing on this row: 1. updates status to "processing" 2. does some processing using content 3. deletes the row we are facing contention issues when we try to run multiple consumers(probably due to the order-by which does a full table scan)... using Advanced queues would be our next step but before we go there we want to check what is the max throughput we can achieve with multiple consumers and producer on the table. What are the optimizations we can do to get the best numbers possible? Can we do an in-memory processing where a consumer fetches 1000 rows at a time processes and deletes? will that improve? What are other possibilities? partitioning of table? parallelization? Index organized tables?...

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• NSFetchedResultsController sort different sections differently (ascending/descending)?

  - by PartiallyFinite

  In my app, I have a task list (no, it's not just another todo app), and I display the tasks in a UITableView using an NSFetchedResultsController. Here is the relevant initialisation code: NSSortDescriptor *dueDateSortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"due" YES]; NSSortDescriptor *completionSortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"completed" ascending:YES]; [fetchRequest setSortDescriptors:[NSArray arrayWithObjects:completionSortDescriptor, dueDateSortDescriptor, nil]]; _fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:@"completed" cacheName:nil]; What this does is sorts the tasks such that I have an incomplete tasks section at the top, sorting with the tasks due first on top, and tasks due later further down. This all works. However, this means that the second section, the one with the completed tasks, also sorts this way, so the earliest due tasks are on top. What I want to do is change it so the second section sorts the other way around (in descending order), but the first section stays sorted in ascending order. Is this even possible? How would I go about this? Why I want to do this: The way it currently works, the tasks at the top of the second section (and therefore the most visible) are the ones that were completed ages ago. It is more likely that the user would want to see the tasks that are more recently completed (and uncheck one if it was accidentally checked), and presumably the tasks with a more recent due date were more recently completed. I am happy to add a separate completion date field to the Core Data task object if necessary (This isn't a shipping application yet, so I can change the data format however I like).

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