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• Windows 8, NVIDIA graphics recognition fails

  - by Roy Grubb

  I just installed Windows 8 Pro OEM 64-bit (clean install) and it won't properly recognize my graphics adapter. When I installed Win8, it automatically installed the BasicDisplay.sys driver dated 6/21/2006. 6.2.9200.16384 (win8_rtm.120725-1247). Hardware - Mobo:MSi G41M-P33 Combo CPU:Intel CoreDuo 6600 Graphics:NVIDIA GeForce 9400GT *OS* - Windows 8 Pro 64-bit OEM The graphics adapter worked fine in Windows XP. The PC is a generic box, bought locally and its mobo failed recently, so I replaced it with the G41M. Microsoft wouldn't let me re-activate Windows XP with a different mobo, so I installed Win8, which appears to work except as described next. Win8 only partially recognizes the graphics adapter and won't allow NVIDIA latest driver installer to see that it's an NVIDIA card. As a result, OpenGL doesn't work, and this is needed by the software I most use. Other than that the graphics look OK. When I say 'partially recognizes', I mean that via the Control Panel, I can see that the adapter is described as NVIDIA, but the driver remains stuck at Microsoft Basic Display Adapter no matter what I try, including "Update driver..." in adapter properties. Display Screen Resolution Advanced Settings Adapter shows: Adapter Type: Microsoft Basic Display Adapter Chip Type: NVIDIA DAC Type: NVIDIA Corporation Bios Information: G27 Board - p381n17 Don't know what this means ... no mention of 9400GT Total Available Graphics Memory: 256 MB Dedicated Video Memory: 0 MB In fact the adapter has 512MB on-board video memory. System Video Memory: 0 MB Shared System Memory: 256 MB And Control Panel Device Manager Display adapters just shows Microsoft Basic Display Adapter. No other graphics adapter, and no unknown device or yellow question mark. What I have tried so far: 1. Cleared CMOS and reset. Updated BIOS and all mobo drivers as follows: 1st I used Driver Reviver to see if any driver updates were required. It found some but I didn't use that to get the drivers. Then I switched to MSi's own mobo driver utility Live Update 5. This also showed the board needed to update several so I used it to fetch the new drivers. After that it showed that everything was up to date and I checked with Driver Reviver again, which also reported no drivers now needed updating. Rebooted. Went to the NVIDIA site to get the latest graphics adapter driver. Their auto-detect "Option 2: Automatically find drivers for my NVIDIA products" said "The NVIDIA Smart Scan was unable to evaluate your system hardware. Please use Option 1 to manually find drivers for your NVIDIA products." So I downloaded 310.70-desktop-win8-win7-winvista-64bit-international-whql.exe, which lists 9400 GT under supported products, but when I run it, it says: "NVIDIA Installer cannot continue This graphics driver could not find compatible graphics hardware." Connected the display to the on-board Intel graphics (G41 Intel Express), removed the NVIDIA card and rebooted, changed to internal graphics in CMOS. Again it installs the MS Basic Display Adapter, and can't properly run my s/w that needs OpenGL. It runs on other machines with Intel Express graphics (WinXP and 7) Shut down and pulled out the power cord. Held start button to discharge all capacitors. Removed and re-inserted NVIDIA adapter in PCI-E slot and made sure properly seated. Connected the monitor to the card, screwed plug to socket. Reconnected power cord. Started and checked in BIOS that Primary Graphics Adapter was set to PCI-E. Started Windows. Uninstalled MS Basic Display Adapter in Device Manager. Screen blanks briefly, reappears. No Graphics adapter entry was then visible in Device Manager. Restarted PC. MS Basic Display Adapter Visible again in Device Manager. Clicked in Device Manager View Show hidden devices. No other graphics adapter appears, no unknown devices. Rebooted. Tried Scan for Hardware changes. None detected. Tried right-click on MS Basic Display Adapter Properties Driver Update Driver... Search automatically. It replied that it had determined driver was up to date. I checked that there were no graphic driver-related entries in Programs and Features that I could delete (none). Searched for any other drivers with nvidia in their name and deleted them, just keeping the 306.97 installer exe file. Did a Windows Update. Ran GPU-Z which shows (main items): Microsoft Basic Display Adapter GPU G72 BIOS 5.72.22.76.88 Device ID 10DE - 01D5 DDR2 Bus Width 32 Bit Memory size 64MB Driver Version nvlddmkm 6.2.9200.16384 (ForceWare 0.00) / Win8 64 NVIDIA SLI Unknown in the drop-down at the foot, "Microsoft Basic Display Adapter" is the only option If I swap hard disks in that machine to one with a Ubuntu 10.4 installation (originally installed on the same PC), lspci shows "VGA compatible controller as NVIDIA Corporation Device 01d5 (rev a1) (prog-if 00 [VGA controller])" and "kernel driver in use: nvidia" I'm out of ideas for new things to try and would be really grateful of suggestions. Thanks!

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• DNS resolution problems; dig SERVFAIL error

  - by JustinP

  I'm setting up a couple of dedicated servers, and having problems setting up my nameservers properly. One of these is a LEMP server (LAMP with nginx in place of Apache), and the other will function solely as an email server, running exim/dovecot/ASSP antispam (no Apache). The LEMP server is CentOS 5.5, with no control panel, while the email server is CentOS 5.5 as well, with cPanel/WHM. So, I've had problems getting DNS set up properly. I have two domains, each one pointing to one of these servers. The nameservers are registered correctly with the domain registrar, and the nameserver IPs are entered correctly as well. I've spoken to tech support at the registrar and they confirm that everything is set up on their end. Not knowing much about DNS, I googled nameservers and DNS until I nearly went blind, and spent hours messing with the configuration. Eventually, I got the LEMP server's DNS working properly (no cPanel). Pleased with this triumph, I'm trying to mimic that configuration and repeat the process with the email server, and it's just not happening. The nameserver starts and stops, but the domain doesn't resolve. Things I have tried Going through standard procedures to set up DNS in WHM Clearing all DNS information, uninstalling BIND, then reinstalling all of that and again going through WHM procedures for setting up DNS Clearing all DNS information, and setting up BIND via shell (completely outside of cPanel) by using my config and zone files from the LEMP server as a template named runs just fine, but nothing is resolving. When I "dig any example.com" I get a SERVFAIL message. Nslookups return no information. Here are my config and zone files. named.conf controls { inet 127.0.0.1 allow { localhost; } keys { coretext-key; }; }; options { listen-on port 53 { any; }; listen-on-v6 port 53 { ::1; }; directory "/var/named"; dump-file "/var/named/data/cache_dump.db"; statistics-file "/var/named/data/named_stats.txt"; memstatistics-file "/var/named/data/named_mem_stats.txt"; // Those options should be used carefully because they disable port // randomization // query-source port 53; // query-source-v6 port 53; allow-query { any; }; allow-query-cache { any; }; }; logging { channel default_debug { file "data/named.run"; severity dynamic; }; }; view "localhost_resolver" { match-clients { 127.0.0.0/24; }; match-destinations { localhost; }; recursion yes; //zone "." IN { // type hint; // file "/var/named/named.ca"; //}; include "/etc/named.rfc1912.zones"; }; view "internal" { /* This view will contain zones you want to serve only to "internal" clients that connect via your directly attached LAN interfaces - "localnets" . */ match-clients { localnets; }; match-destinations { localnets; }; recursion yes; zone "." IN { type hint; file "/var/named/named.ca"; }; // include "/var/named/named.rfc1912.zones"; // you should not serve your rfc1912 names to non-localhost clients. // These are your "authoritative" internal zones, and would probably // also be included in the "localhost_resolver" view above : zone "example.com" { type master; file "data/db.example.com"; }; zone "3.2.1.in-addr.arpa" { type master; file "data/db.1.2.3"; }; }; view "external" { /* This view will contain zones you want to serve only to "external" clients * that have addresses that are not on your directly attached LAN interface subnets: */ match-clients { any; }; match-destinations { any; }; recursion no; // you'd probably want to deny recursion to external clients, so you don't // end up providing free DNS service to all takers allow-query-cache { none; }; // Disable lookups for any cached data and root hints // all views must contain the root hints zone: //include "/etc/named.rfc1912.zones"; zone "." IN { type hint; file "/var/named/named.ca"; }; zone "example.com" { type master; file "data/db.example.com"; }; zone "3.2.1.in-addr.arpa" { type master; file "data/db.1.2.3"; }; }; include "/etc/rndc.key"; db.example.com $TTL 1D ; ; Zone file for example.com ; ; Mandatory minimum for a working domain ; @ IN SOA ns1.example.com. contact.example.com. ( 2011042905 ; serial 8H ; refresh 2H ; retry 4W ; expire 1D ; default_ttl ) NS ns1.example.com. NS ns2.example.com. ns1 A 1.2.3.4 ns2 A 1.2.3.5 example.com. A 1.2.3.4 localhost A 127.0.0.1 www CNAME example.com. mail CNAME example.com. ; db.1.2.3 $TTL 1D $ORIGIN 3.2.1.in-addr.arpa. @ IN SOA ns1.example.com contact.example.com. ( 2011042908 ; 8H ; 2H ; 4W ; 1D ; ) NS ns1.example.com. NS ns2.example.com. 4 PTR hostname.example.com. 5 PTR hostname.example.com. ; Also of note: both of these servers are managed. Tech support is very responsive, and largely useless. Hours go by with them asking me questions to narrow down what could be wrong, then they pass the ticket to the tech on the next shift, who ignores everything that's happened already and spend his whole shift asking all the same questions the last guy asked. So, in summary: *Nameservers, with IPs, are correctly registered with domain registrar *named is configured and running *...and must not be configured correctly, because nothing resolves. Any help would be great. I changed domains and IPs in the files to generics, but let me know if you need to know the domain in question. Thanks! UPDATE I found that I didn't have 127.0.0.1 in /etc/resolv.conf, so I added it, along with my two public IPs that I have named listening on. resolv.conf search www.example.com example.com nameserver 127.0.0.1 nameserver 7.8.9.10 ;Was in here by default, authoritative nameserver of hosting company nameserver 1.2.3.4 ;Public IP #1 nameserver 1.2.3.5 ;Public IP #2 Now when I DIG example.com from the host, it resolves. If I try to DIG from my other server (in the same datacenter), or from the internet, it times out or I get SERVFAIL.

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• Paying great programmers more than average programmers

  - by Kelly French

  It's fairly well recognized that some programmers are up to 10 times more productive than others. Joel mentions this topic on his blog. There is a whole blog devoted to the idea of the "10x productive programmer". In years since the original study, the general finding that "There are order-of-magnitude differences among programmers" has been confirmed by many other studies of professional programmers (Curtis 1981, Mills 1983, DeMarco and Lister 1985, Curtis et al. 1986, Card 1987, Boehm and Papaccio 1988, Valett and McGarry 1989, Boehm et al 2000). Fred Brooks mentions the wide range in the quality of designers in his "No Silver Bullet" article, The differences are not minor--they are rather like the differences between Salieri and Mozart. Study after study shows that the very best designers produce structures that are faster, smaller, simpler, cleaner, and produced with less effort. The differences between the great and the average approach an order of magnitude. The study that Brooks cites is: H. Sackman, W.J. Erikson, and E.E. Grant, "Exploratory Experimental Studies Comparing Online and Offline Programming Performance," Communications of the ACM, Vol. 11, No. 1 (January 1968), pp. 3-11. The way programmers are paid by employers these days makes it almost impossible to pay the great programmers a large multiple of what the entry-level salary is. When the starting salary for a just-graduated entry-level programmer, we'll call him Asok (From Dilbert), is $40K, even if the top programmer, we'll call him Linus, makes $120K that is only a multiple of 3. I'd be willing to be that Linus does much more than 3 times what Asok does, so why wouldn't we expect him to get paid more as well? Here is a quote from Stroustrup: "The companies are complaining because they are hurting. They can't produce quality products as cheaply, as reliably, and as quickly as they would like. They correctly see a shortage of good developers as a part of the problem. What they generally don't see is that inserting a good developer into a culture designed to constrain semi-skilled programmers from doing harm is pointless because the rules/culture will constrain the new developer from doing anything significantly new and better." This leads to two questions. I'm excluding self-employed programmers and contractors. If you disagree that's fine but please include your rationale. It might be that the self-employed or contract programmers are where you find the top-10 earners, but please provide a explanation/story/rationale along with any anecdotes. [EDIT] I thought up some other areas in which talent/ability affects pay. Financial traders (commodities, stock, derivatives, etc.) designers (fashion, interior decorators, architects, etc.) professionals (doctor, lawyer, accountant, etc.) sales Questions: Why aren't the top 1% of programmers paid like A-list movie stars? What would the industry be like if we did pay the "Smart and gets things done" programmers 6, 8, or 10 times what an intern makes? [Footnote: I posted this question after submitting it to the Stackoverflow podcast. It was included in episode 77 and I've written more about it as a Codewright's Tale post 'Of Rockstars and Bricklayers'] Epilogue: It's probably unfair to exclude contractors and the self-employed. One aspect of the highest earners in other fields is that they are free-agents. The competition for their skills is what drives up their earning power. This means they can not be interchangeable or otherwise treated as a plug-and-play resource. I liked the example in one answer of a major league baseball team trying to field two first-basemen. Also, something that Joel mentioned in the Stackoverflow podcast (#77). There are natural dynamics to shrink any extreme performance/pay ranges between the highs and lows. One is the peer pressure of organizations to pay within a given range, another is the likelyhood that the high performer will realize their undercompensation and seek greener pastures.

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• Synapse and string problems with HTTPSend in Delphi 2010

  - by Mick

  I have been trying to get to the bottom of this problem off and on for the past 2 days and I'm really stuck. Hopefully some smart folks can help me out. The issue is that I have a function that I call in a thread that downloads a file (using Synapse libraries) from a website that is passed to it. However, I've found that every once in a while there are sites where it will not pull down a file, but wget or Firefox/IE will download it without issue. Digging into it, I've found some curious things. Here is the relevant code: uses //[..] HTTPSend, blcksock; //[..] type TMyThread = class(TThread) protected procedure Execute; override; private { Private declarations } fTheUrl: string; procedure GetFile(const TheUrl: string); public property thrd_TheUrl: string read fTheUrl write fTheUrl; end; implementation [..] procedure TMyThread.GetFile(const TheUrl: string); var HTTP: THTTPSend; success: boolean; sLocalUrl: string; IsSame : boolean; begin HTTP := THTTPSend.Create; try HTTP.UserAgent := 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727)'; HTTP.ProxyHost := 'MYPROXY.COM'; HTTP.ProxyPort := '80'; sLocalUrl := 'http://web.archive.org/web/20071212205017/energizer.com/usbcharger/download/UsbCharger_setup_V1_1_1.exe'; IsSame := SameText(sLocalUrl, sTheUrl); //this equals True when I debug /// /// /// THIS IS WHERE THE ISSUE BEGINS /// I will comment out 1 of the following when debugging /// HTTP.HTTPMethod('GET', sLocalUrl); // ----this works and WILL download the file HTTP.HTTPMethod('GET', sTheUrl); // --- this always fails, and HTTP.ResultString contains "Not Found" success := SysUtils.UpperCase(HTTP.ResultString) = 'OK'; if HTTP.ResultCode > 0 then success := True; //this is here just to keep the value around while debugging finally HTTP.Free; end; end; procedure TMyThread.Execute begin //fTheURL contains this value: http://web.archive.org/web/20071212205017/energizer.com/usbcharger/download/UsbCharger_setup_V1_1_1.exe GetFile(fTheUrl); end; The problem is that when I assign a local variable to the function and give it the URL directly, everything works. However, when passing the variable into the function, it fails. Anyone have any ideas? HTTP.HTTPMethod('GET', sLocalUrl); // ----this works and WILL download the file HTTP.HTTPMethod('GET', sTheUrl); // --- this always fails, and HTTP.ResultString contains "Not Found" I'm using the latest version of Synapse from their SVN repository (version from 2 days ago). NOTE: The file I am attempting to download is known to have a virus, the program I am writing is meant to download malicious files for analysis. So, don't execute the file once you download it. However, I'm using this URL b/c this is the one I can reproduce the issue with.

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• Getting JAX-WS client work on Weblogic 9.2 with ant

  - by michuk

  I've recently had lots of issues trying to deploy a JAX-WS web servcie client on Weblogic 9.2. It turns out there is no straightforward guide on how to achieve this, so I decided to put together this short wiki entry hoping it might be useful for others. Firstly, Weblogic 9.2 does not support web servcies using JAX-WS in general. It comes with old versions of XML-related java libraries that are incompatible with the latest JAX-WS (similar issues occur with Axis2, only Axis1 seems to be working flawlessly with Weblogic 9.x but that's a very old and unsupported library). So, in order to get it working, some hacking is required. This is how I did it (note that we're using ant in our legacy corporate project, you probably should be using maven which should eliminate 50% of those steps below): Download the most recent JAX-WS distribution from https://jax-ws.dev.java.net/ (The exact version I got was JAXWS2.2-20091203.zip) Place the JAX-WS jars with the dependencies in a separate folder like lib/webservices. Create a patternset in ant to reference those jars: Include the patternset in your WAR-related goal. This could look something like: (not the flatten="true" parameter - it's important as Weblogic 9.x is by default not smart enough to access jars located in a different lcoation than WEB-INF/lib inside your WAR file) In case of clashes, Weblogic uses its own jars by default. We want it to use the JAX-WS jars from our application instead. This is achieved by preparing a weblogic-application.xml file and placing it in META-INF folder of the deplotyed EAR file. It should look like this: javax.jws. javax.xml.bind. javax.xml.crypto. javax.xml.registry. javax.xml.rpc. javax.xml.soap. javax.xml.stream. javax.xml.ws. com.sun.xml.api.streaming.* Remember to place that weblogic-application.xml file in your EAR! The ant goal for that may look similar to: <jar destfile="${warfile}" basedir="${wardir}"/> <ear destfile="${earfile}" appxml="resources/${app.name}/application.xml"> <fileset dir="${dist}" includes="${app.name}.war"/> <metainf dir="resources/META-INF"/> </ear> Also you need to tell weblogic to prefer your WEB-INF classes to those in distribution. You do that by placing the following lines in your WEB-INF/weblogic.xml file: true And that's it for the weblogic-related configuration. Now only set up your JAX-WS goal. The one below is going to simply generate the web service stubs and classes based on a locally deployed WSDL file and place them in a folder in your app: Remember about the keep="true" parameter. Without it, wsimport generates the classes and... deletes them, believe it or not! For mocking a web service I suggest using SOAPUI, an open source project. Very easy to deploy, crucial for web servcies intergation testing. We're almost there. The final thing is to write a Java class for testing the web service, try to run it as a standalone app first (or as part of your unit tests) And then try to run the same code from withing Weblogic. It should work. It worked for me. After some 3 days of frustration. And yes, I know I should've put 9 and 10 under a single bullet-point, but the title "10 steps to deploy a JAX-WS web service under Web logic 9.2 using ant" sounds just so much better. Please, edit this post and improve it if you find something missing!

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• NHibernate which cache to use for WinForms application

  - by chiccodoro

  I have a C# WinForms application with a database backend (oracle) and use NHibernate for O/R mapping. I would like to reduce communication to the database as much as possible since the network in here is quite slow, so I read about second level caching. I found this quite good introduction, which lists the following available cache implementations. I'm wondering which implementation I should use for my application. The caching should be simple, it should not significantly slow down the first occurrence of a query, and it should not take much memory to load the implementing assemblies. (With NHibernate and Castle, the application already takes up to 80 MB of RAM!) Velocity: uses Microsoft Velocity which is a highly scalable in-memory application cache for all kinds of data. Prevalence: uses Bamboo.Prevalence as the cache provider. Bamboo.Prevalence is a .NET implementation of the object prevalence concept brought to life by Klaus Wuestefeld in Prevayler. Bamboo.Prevalence provides transparent object persistence to deterministic systems targeting the CLR. It offers persistent caching for smart client applications. SysCache: Uses System.Web.Caching.Cache as the cache provider. This means that you can rely on ASP.NET caching feature to understand how it works. SysCache2: Similar to NHibernate.Caches.SysCache, uses ASP.NET cache. This provider also supports SQL dependency-based expiration, meaning that it is possible to configure certain cache regions to automatically expire when the relevant data in the database changes. MemCache: uses memcached; memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load. Basically a distributed hash table. SharedCache: high-performance, distributed and replicated memory object caching system. See here and here for more info My considerations so far were: Velocity seems quite heavyweight and overkill (the files totally take 467 KB of disk space, haven't measured the RAM it takes so far because I didn't manage to make it run, see below) Prevalence, at least in my first attempt, slowed down my query from ~0.5 secs to ~5 secs, and caching didn't work (see below) SysCache seems to be for ASP.NET, not for winforms. MemCache and SharedCache seem to be for distributed scenarios. Which one would you suggest me to use? There would also be a built-in implementation, which of course is very lightweight, but the referenced article tells me that I "(...) should never use this cache provider for production code but only for testing." Besides the question which fits best into my situation I also faced problems with applying them: Velocity complained that "dcacheClient" tag not specified in the application configuration file. Specify valid tag in configuration file," although I created an app.config file for the assembly and pasted the example from this article. Prevalence, as mentioned above, heavily slowed down my first query, and the next time the exact same query was executed, another select was sent to the database. Maybe I should "externalize" this topic into another post. I will do that if someone tells me it is absolutely unusual that a query is slowed down so much and he needs further details to help me.

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• starting with flex - please let me know if the direction is right (ActionScript vs MXML separation)

  - by Piotr

  Hi, I've just started learning flex using OReilly "Programming Flex 3.0". After completing three chapters and starting fourth (ActionScript), and not having enough patience to wait till completing chapter 22 I started to practice :) One bit that I have most worries about right now is the the dual coding mode (MXML vs ActionScript) Please have a look at my code below (it compiles via mxmlc design.mxml, second file 'code.as' should be in same directory) and advise if the separation I used between visual design and code is appropriate. Also - if some smart guy could show me how to recode same example with *.as being a class file [package?] it would be highly appreciated. I got lost with creating directory structure for package - and did not find it most intuitive, especially for small project that has two files like my example. Code: design.mxml <?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:Script source="code.as"/> <mx:VBox> <mx:TextInput creationComplete="initializeCalculator()" id="txtScreen"/> <mx:HBox> <mx:Button click="click('7')" id="btn7" label="7"/> <mx:Button click="click('8')" id="btn8" label="8"/> <mx:Button click="click('9')" id="btn9" label="9"/> <mx:Button click="click('C')" id="btnClear" label="C"/> </mx:HBox> <mx:HBox> <mx:Button click="click('4')" id="btn4" label="4"/> <mx:Button click="click('5')" id="btn5" label="5"/> <mx:Button click="click('6')" id="btn6" label="6"/> <mx:Button click="click('/')" id="btnDivide" label="/"/> </mx:HBox> <mx:HBox> <mx:Button click="click('1')" id="btn1" label="1"/> <mx:Button click="click('2')" id="btn2" label="2"/> <mx:Button click="click('3')" id="btn3" label="3"/> <mx:Button click="click('*')" id="btnMultiply" label="*"/> </mx:HBox> <mx:HBox> <mx:Button click="click('0')" id="btn0" label="0"/> <mx:Button click="click('=')" id="btnEqual" label="="/> <mx:Button click="click('-')" id="btnMinus" label="-"/> <mx:Button click="click('+')" id="btnPlus" label="+"/> </mx:HBox> </mx:VBox> </mx:Application> code: code.as public var res:int = 0; public var previousOperator:String = ""; public var previousRes:int=0; public function initializeCalculator():void{ txtScreen.text = res.toString(); } public function click(code:String):void{ if (code=="1" || code=="2" || code=="3" || code=="4" || code=="5" || code=="6" || code=="7" || code=="8" || code=="9" || code=="0"){ res = res*10 + int(code); txtScreen.text = res.toString(); } else if (code=="C"){ res = 0; previousOperator =""; previousRes = 0; txtScreen.text = res.toString(); } else{ calculate(code); } } public function calculate(operator:String):void{ var tmpRes:int; if (previousOperator=="+"){ tmpRes = previousRes + res; } else if (previousOperator=="-"){ tmpRes = previousRes - res; } else if (previousOperator=="/"){ tmpRes = previousRes / res; } else if (previousOperator=="*"){ tmpRes = previousRes * res; } else{ tmpRes = res; } previousOperator = operator; previousRes = tmpRes; txtScreen.text = previousRes.toString(); res = 0; if (previousOperator=="=") { res = tmpRes; txtScreen.text=res.toString(); } } PS. If you have comments that this calculator does not calculate properly, they are also appreciated, yet most important are comments on best practices in Flex.

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• How to solve JAVA menubar, layout and panel problem ?

  - by Berkay

  i'm not a java guy however i start implementing some security tools with java, in these days i'm creating a gui for my security tools : Here is the how my Gui looks: menuBar = new JMenuBar(); // construct menu bar // hash functions fileMenu = new JMenu("HASH FUNCTIONS"); // define file menu fileMenu.setMnemonic('H'); // shortcut hashes = new JMenuItem("Md5&Sha1"); // define file menu options hashes.setMnemonic('M'); hashes.addActionListener(this); fileMenu.add(hashes); menuBar.add(fileMenu); // add file menu to menu bar // symmetric encryption asMenu = new JMenu("SYMMETRIC ENCRYPTION"); // define format menu asMenu.setMnemonic('S'); // shortcut desItem = new JMenuItem("DES"); // define format menu options desItem.setMnemonic('D'); desItem.addActionListener(this); asMenu.add(desItem); ... ... menuBar.add(helpMenu); // add help menu to menu bar setJMenuBar(menuBar); // put menu bar on application textColor = Color.RED; when from the Menu desitem is selected, desvar is just for not showing the panel multiple times, it calls Panels () else if(e.getSource() == desItem && desvar ==1 ) { // make other panels unvisible. if(hashvar!=1) MyPanel.setVisible(false);//hash functions if(rsavar!=1) MyPanel3.setVisible(false);//rsa function if (dhvar!=1) MyPanel4.setVisible(false);//dh diffie hellman hashvar=1; rsavar=1; dhvar=1; ++desvar; desPanel=true; Panels(); } and in Panels() Method: if (hashPanel){ MyPanel.add("West",radioSHA1); MyPanel.add("West",radioMD5); MyPanel.add("Center", inputField); MyPanel.add("East",SubmitButton); MyPanel.add("South",resultHash); add(MyPanel); validate(); hashPanel=false; } i have many panels for example : -hash functions=mypanel1 , des=mypanel2, rsa functions= mypanel3 , dh= mypanel4 However in may other panals such as rsa function: i have to use some layout properties of the java:in this panel i selected to use gridbaglayout if (dhPanel){ System.out.println("rsa panel burda misin"); MyPanel3.add(pqLabel); MyPanel3.add(pLabel); MyPanel3.add(pTextArea); MyPanel3.add(qLabel); ... ... add(MyPanel3); generate_pqButton.addActionListener(this); calculate_nButton.addActionListener(this); ... ... GridBagLayout layout = new GridBagLayout(); GridBagConstraints gbc = new GridBagConstraints(); setLayout(layout); // x, y, w, h, wx, wy gbc.fill = GridBagConstraints.NONE; add (bit_length_label, gbc, 0, 0, 1, 1, 0, 10); add (p, gbc, 0, 1, 1, 1, 0, 10); add (g, gbc, 0, 2, 1, 1, 0, 10); add (a, gbc, 1, 3, 1, 1, 100, 10); add (x, gbc, 0, 4, 1, 1, 0, 10); add (gx, gbc, 0, 5, 1, 1, 0, 10); add (gxy, gbc, 0, 6, 1, 1, 0, 10); add (b, gbc, 1, 7, 1, 1, 100, 10); add (y, gbc, 0, 8, 1, 1, 0, 10); add (gy, gbc, 0, 9, 1, 1, 0, 10); add (gyx, gbc, 0, 10, 1, 1, 0, 10); add (sk, gbc, 1, 11, 1, 1, 100, 10); add (key, gbc, 0, 12, 1, 1, 0, 10); add (status, gbc, 1, 13, 1, 1, 100, 10); add (dhstart, gbc, 1, 14, 1, 1, 100, 10); add (bit_length_value, gbc, 1, 0, 1, 1, 100, 10); add (p_value, gbc, 1, 1, 1, 1, 100, 10); add (g_value, gbc, 1, 2, 1, 1, 100, 10); add (x_value, gbc, 1, 4, 1, 1, 100, 10); add (gx_value, gbc, 1, 5, 1, 1, 100, 10); add (gxy_value, gbc, 1, 6, 1, 1, 100, 10); add (y_value, gbc, 1, 8, 1, 1, 100, 10); add (gy_value, gbc, 1, 9, 1, 1, 100, 10); add (gyx_value, gbc, 1, 10, 1, 1, 100, 10); validate(); repaint(); rsaPanel=false; } Everthing seems okey however when i swith from one menu to another sometimes components are seen or apper in wrong places or mixed. where i'm doing wrong?

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• Overflow exception while performing parallel factorization using the .NET Task Parallel Library (TPL

  - by Aviad P.

  Hello, I'm trying to write a not so smart factorization program and trying to do it in parallel using TPL. However, after about 15 minutes of running on a core 2 duo machine, I am getting an aggregate exception with an overflow exception inside it. All the entries in the stack trace are part of the .NET framework, the overflow does not come from my code. Any help would be appreciated in figuring out why this happens. Here's the commented code, hopefully it's simple enough to understand: class Program { static List<Tuple<BigInteger, int>> factors = new List<Tuple<BigInteger, int>>(); static void Main(string[] args) { BigInteger theNumber = BigInteger.Parse( "653872562986528347561038675107510176501827650178351386656875178" + "568165317809518359617865178659815012571026531984659218451608845" + "719856107834513527"); Stopwatch sw = new Stopwatch(); bool isComposite = false; sw.Start(); do { /* Print out the number we are currently working on. */ Console.WriteLine(theNumber); /* Find a factor, stop when at least one is found (using the Any operator). */ isComposite = Range(theNumber) .AsParallel() .Any(x => CheckAndStoreFactor(theNumber, x)); /* Of the factors found, take the one with the lowest base. */ var factor = factors.OrderBy(x => x.Item1).First(); Console.WriteLine(factor); /* Divide the number by the factor. */ theNumber = BigInteger.Divide( theNumber, BigInteger.Pow(factor.Item1, factor.Item2)); /* Clear the discovered factors cache, and keep looking. */ factors.Clear(); } while (isComposite); sw.Stop(); Console.WriteLine(isComposite + " " + sw.Elapsed); } static IEnumerable<BigInteger> Range(BigInteger squareOfTarget) { BigInteger two = BigInteger.Parse("2"); BigInteger element = BigInteger.Parse("3"); while (element * element < squareOfTarget) { yield return element; element = BigInteger.Add(element, two); } } static bool CheckAndStoreFactor(BigInteger candidate, BigInteger factor) { BigInteger remainder, dividend = candidate; int exponent = 0; do { dividend = BigInteger.DivRem(dividend, factor, out remainder); if (remainder.IsZero) { exponent++; } } while (remainder.IsZero); if (exponent > 0) { lock (factors) { factors.Add(Tuple.Create(factor, exponent)); } } return exponent > 0; } } Here's the exception thrown: Unhandled Exception: System.AggregateException: One or more errors occurred. --- > System.OverflowException: Arithmetic operation resulted in an overflow. at System.Linq.Parallel.PartitionedDataSource`1.ContiguousChunkLazyEnumerator.MoveNext(T& currentElement, Int32& currentKey) at System.Linq.Parallel.AnyAllSearchOperator`1.AnyAllSearchOperatorEnumerator`1.MoveNext(Boolean& currentElement, Int32& currentKey) at System.Linq.Parallel.StopAndGoSpoolingTask`2.SpoolingWork() at System.Linq.Parallel.SpoolingTaskBase.Work() at System.Linq.Parallel.QueryTask.BaseWork(Object unused) at System.Linq.Parallel.QueryTask.<.cctor>b__0(Object o) at System.Threading.Tasks.Task.InnerInvoke() at System.Threading.Tasks.Task.Execute() --- End of inner exception stack trace --- at System.Linq.Parallel.QueryTaskGroupState.QueryEnd(Boolean userInitiatedDispose) at System.Linq.Parallel.SpoolingTask.SpoolStopAndGo[TInputOutput,TIgnoreKey](QueryTaskGroupState groupState, PartitionedStream`2 partitions, SynchronousChannel`1[] channels, TaskScheduler taskScheduler) at System.Linq.Parallel.DefaultMergeHelper`2.System.Linq.Parallel.IMergeHelper<TInputOutput>.Execute() at System.Linq.Parallel.MergeExecutor`1.Execute[TKey](PartitionedStream`2 partitions, Boolean ignoreOutput, ParallelMergeOptions options, TaskScheduler taskScheduler, Boolean isOrdered, CancellationState cancellationState, Int32 queryId) at System.Linq.Parallel.PartitionedStreamMerger`1.Receive[TKey](PartitionedStream`2 partitionedStream) at System.Linq.Parallel.AnyAllSearchOperator`1.WrapPartitionedStream[TKey](PartitionedStream`2 inputStream, IPartitionedStreamRecipient`1 recipient, BooleanpreferStriping, QuerySettings settings) at System.Linq.Parallel.UnaryQueryOperator`2.UnaryQueryOperatorResults.ChildResultsRecipient.Receive[TKey](PartitionedStream`2 inputStream) at System.Linq.Parallel.ScanQueryOperator`1.ScanEnumerableQueryOperatorResults.GivePartitionedStream(IPartitionedStreamRecipient`1 recipient) at System.Linq.Parallel.UnaryQueryOperator`2.UnaryQueryOperatorResults.GivePartitionedStream(IPartitionedStreamRecipient`1 recipient) at System.Linq.Parallel.QueryOperator`1.GetOpenedEnumerator(Nullable`1 mergeOptions, Boolean suppressOrder, Boolean forEffect, QuerySettings querySettings) at System.Linq.Parallel.QueryOpeningEnumerator`1.OpenQuery() at System.Linq.Parallel.QueryOpeningEnumerator`1.MoveNext() at System.Linq.Parallel.AnyAllSearchOperator`1.Aggregate() at System.Linq.ParallelEnumerable.Any[TSource](ParallelQuery`1 source, Func`2 predicate) at PFact.Program.Main(String[] args) in d:\myprojects\PFact\PFact\Program.cs:line 34 Any help would be appreciated. Thanks!

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• Is the Cloud ready for an Enterprise Java web application? Seeking a JEE hosting advice.

  - by Jakub Holý

  Greetings to all the smart people around here! I'd like to ask whether it is feasible or a good idea at all to deploy a Java enterprise web application to a Cloud such as Amazon EC2. More exactly, I'm looking for infrastructure options for an application that shall handle few hundred users with long but neither CPU nor memory intensive sessions. I'm considering dedicated servers, virtual private servers (VPSs) and EC2. I've noticed that there is a project called JBoss Cloud so people are working on enabling such a deployment, on the other hand it doesn't seem to be mature yet and I'm not sure that the cloud is ready for this kind of applications, which differs from the typical cloud-based applications like Twitter. Would you recommend to deploy it to the cloud? What are the pros and cons? The application is a Java EE 5 web application whose main function is to enable users to compose their own customized Product by combining the available Parts. It uses stateless and stateful session beans and JPA for persistence of entities to a RDBMS and fetches information about Parts from the company's inventory system via a web service. Aside of external users it's used also by few internal ones, who are authenticated against the company's LDAP. The application should handle around 300-400 concurrent users building their product and should be reasonably scalable and available though these qualities are only of a medium importance at this stage. I've proposed an architecture consisting of a firewall (FW) and load balancer supporting sticky sessions and https (in the Cloud this would be replaced with EC2's Elastic Load Balancing service and FW on the app. servers, in a physical architecture the load-balancer would be a HW), then two physical clustered application servers combined with web servers (so that if one fails, a user doesn't loose his/her long built product) and finally a database server. The DB server would need a slave backup instance that can replace the master instance if it fails. This should provide reasonable availability and fault tolerance and provide good scalability as long as a single RDBMS can keep with the load, which should be OK for quite a while because most of the operations are done in the memory using a stateful bean and only occasionally stored or retrieved from the DB and the amount of data is low too. A problematic part could be the dependency on the remote inventory system webservice but with good caching of its outputs in the application it should be OK too. Unfortunately I've only vague idea of the system resources (memory size, number and speed of CPUs/cores) that such an "average Java EE application" for few hundred users needs. My rough and mostly unfounded estimate based on actual Amazon offerings is that 1.7GB and a single, 2-core "modern CPU" with speed around 2.5GHz (the High-CPU Medium Instance) should be sufficient for any of the two application servers (since we can handle higher load by provisioning more of them). Alternatively I would consider using the Large instance (64b, 7.5GB RAM, 2 cores at 1GHz) So my question is whether such a deployment to the cloud is technically and financially feasible or whether dedicated/VPS servers would be a better option and whether there are some real-world experiences with something similar. Thank you very much! /Jakub Holy PS: I've found the JBoss EAP in a Cloud Case Study that shows that it is possible to deploy a real-world Java EE application to the EC2 cloud but unfortunately there're no details regarding topology, instance types, or anything :-(

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• WebSphere Application Server EJB Optimization

  - by Chris Aldrich

  We are working on developing a Java EE based application. Our application is Java 1.5 compatible and will be deployed to WAS ND 6.1.0.21 with EBJ 3.0 and Web Services feature packs. The configuration is currently one cell with two clusters. Each cluster will have two nodes. Our application, or our system, as I should rather say, comes in two or three parts. Part 1: An ear deployed to one cluster that contains 3rd party vendor code combined with customization code. Their code is EJB 2.0 compliant and has a lot of Remote Home interfaces. Part 2: An ear deployed to the same cluster as the first ear. This ear contains EBJ 3's that make calls into the EJB 2's supplied by the vendor and the custom code. These EJB 3's are used by the JSF UI also packaged with the EAR, and some of them are also exposed as web services (JAX-WS 2.0 with SOAP 1.2 compliance) for other clients. Part 3: There may be other services that do not depend on our vendor/custom code app. These services will be EJB 3.0's and web services that are deployed to the other cluster. Per a recommendation from some IBM staff on site here, communication between nodes in a cluster can be EJB RMI. But if we are going across clusters and/or other cells, then the communication should be web services. That said, some of us are wondering about performance and optimizing communication for speed of our applications that will use our web services and EJB's. Right now most EJB's are exposed as remote. (and our vendor set theirs up that way, rather than also exposing local home interfaces). We are wondering if WAS does any optimizations between apps in the same node/cluster node space. If two apps are installed in the same area and they call each other via remote home interface, is WAS smart enough to make it a local home interface call? Are their other optimization techniques? Should we consider them? Should we not? What are the costs/benefits? Here is the question from one of our team members as sent in their email: The question is: Supposing we develop our EJBs as remote EJBs, where our UI controller code is talking to our EXT java services via EJB3...what are our options for performance optimization when both the EJB server and client are running in the same container? As one point of reference, google has given me some oooooold websphere performance tuning documentation from 2000 that explains a tuning configuration you can set to enable Call By Reference for EJB communication when they're in the same application server JVM. It states the following: Because EJBs are inherently location independent, they use a remote programming model. Method parameters and return values are serialized over RMI-IIOP and returned by value. This is the intrinsic RMI "Call By Value" model. WebSphere provides the "No Local Copies" performance optimization for running EJBs and clients (typically servlets) in the same application server JVM. The "No Local Copies" option uses "Call By Reference" and does not create local proxies for called objects when both the client and the remote object are in the same process. Depending on your workload, this can result in a significant overhead savings. Configure "No Local Copies" by adding the following two command line parameters to the application server JVM: * -Djavax.rmi.CORBA.UtilClass=com.ibm.CORBA.iiop.Util * -Dcom.ibm.CORBA.iiop.noLocalCopies=true CAUTION: The "No Local Copies" configuration option improves performance by changing "Call By Value" to "Call By Reference" for clients and EJBs in the same JVM. One side effect of this is that the Java object derived (non-primitive) method parameters can actually be changed by the called enterprise bean. Consider Figure 16a: Also, we will also be using Process Server 6.2 and WESB 6.2 as well in the future. Any ideas? recommendations? Thanks

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• MovieClip, counter almost working AS3

  - by VideoDnd

  How do I get my counter to work? This was over my director's head. Please include explanation, and feel free to comment. CONFUSION: I'm confused about the MovieClip container in as3. public class NumbersView extends MovieClip, so that seems to be a container. That may not be the problem, but that's where I got lost. CODE http://videodnd.weebly.com/ The working version of this code is fantastic. My code bellow is an attempt at revising it. The source has been adapted from various smart people. It's a work in progress LIBRARY OBJECT 'vertical number column' Name: mc-NumberImage Class: NumberImage OUTPUT ERRORS 'When I uncomment the code" 1023: Incompatible override. NumbersView... 1021: Duplicate function definition. NumbersView... //NUMBER DOCUMENT CLASS //IMPORT import flash.display.Sprite; import flash.events.Event; import flash.utils.Timer; import flash.events.TimerEvent; import flash.display.DisplayObject; import flash.display.MovieClip; import flash.utils.Dictionary; import caurina.transitions.Tweener; //COUNTER var timer:Timer = new Timer(1000); var count:int = 0; var fcount:int = 0; timer.addEventListener(TimerEvent.TIMER, incrementCounter); timer.start(); function incrementCounter(event:TimerEvent) { count++; fcount=int(count*count/1000); } function formatCount(i:int):String { var fraction:int = i % 100; var whole:int = i / 100; return ("000000000" + i).substr(-9, 9); } //------------------------------------------------------------------------ //PROBLEM AREA function enterFrameHandler(e:Event):void { // numbers.setTime(formatCount(fcount)); } var _listItems:Array = new Array(); var previousNums:Array; const numHeight:int = 120; var NumbersView:Sprite = new Sprite(); //var numbers:NumbersView = new NumbersView; //NUMBERSVIEW // function NumbersView($n:int):void { _listItems = new Array(); previousNums = new Array(); var item:NumberImage; var offset:int = _listItems.length; for (var i:Number = 0; i < 9; i++) { item = new NumberImage(); // }//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< //------------------------------------------------------------------------ //PUSH ARRAY addChild(item); item.x = i * item.width; _listItems.push(item); } //TWEENER 'Y SCROLLING' function setTime($number:String):void { var nums:Array = $number.split(""); for (var i:Number = 0; i < nums.length; i++) { if (nums[i] == previousNums[i]) continue; Tweener.removeTweens(_listItems[i]); var newY:int = int(nums[i]) * -numHeight; if (_listItems[i].y < 0) _listItems[i].y = numHeight; Tweener.addTween(_listItems[i], { y:newY, time:3 } ); } previousNums = nums; } D E S C R I P T I O N COUNTER: formatCount needs to get passed to Tweener STAGE: for loop, sets up children to be added to the stage NumbersView becomes item, item array adds children to stage TWEENER: advances the vertical number column every time the count fires adds and removes WHY - Learning - Benifit in simplifying the classes and putting it in one FLA

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• Android launches system settings instead of my app

  - by jsundin

  Hi, For some reason whenever I (try to) start my app the phone decides to launch system settings instead of my "main activity". And yes, I am referring to the "Android system settings", and not something from my app. This only happens on my phone, and I suppose it probably could be related to the fact that my app had just opened system settings when I decided to re-launch with a new version from Eclipse. It is possible to start the app from within Eclipse, but when I navigate back from the app it returns to the system settings rather than the home screen, as if the settings activity was started first and then my activity. If I then start the app from the phone all I get is system settings yet again. The app is listening to the VIEW-action for a specific URL substring, and when I start the app using a matching URL I get the same result as when I start it from Eclipse, app starts, but when I return I return to settings. I have tried googling for this problem, and all I could find was something about Android saving state when an app gets killed, but without any information on how to reset this state. I have tried uninstalling the app, killing system settings, rebooting the phone, reinstalling, clearing application data.. no luck.. For what it's worth, here's the definition of my main activity from the manifest, <activity android:name=".HomeActivity" android:label="@string/app_name" android:screenOrientation="portrait" android:clearTaskOnLaunch="true" android:launchMode="singleTop"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> <intent-filter> <action android:name="android.intent.action.VIEW"></action> <category android:name="android.intent.category.DEFAULT"></category> <category android:name="android.intent.category.BROWSABLE"></category> <data android:pathPrefix="/isak-web-mobile/smart/" android:scheme="http" android:host="*"></data> </intent-filter> </activity> And here is the logcat-line from when I try to start my app, nothing about any settings anywhere. I/ActivityManager( 1301): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=se.opencare.isak/.HomeActivity } When I launch from Eclipse I also get this line (as one would expect), I/ActivityManager( 1301): Start proc se.opencare.isak for activity se.opencare.isak/.HomeActivity: pid=23068 uid=10163 gids={3003, 1007, 1015} If it matters the phone is a HTC Desire Z running 2.2.1. Currently, this is my HomeActivity, public class HomeActivity extends Activity { public static final String TAG = "HomeActivity"; @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { Log.d(TAG, "onActivityResult(" + requestCode + ", " + resultCode + ", " + data + ")"); super.onActivityResult(requestCode, resultCode, data); } @Override protected void onCreate(Bundle savedInstanceState) { Log.d(TAG, "onCreate(" + savedInstanceState + ")"); super.onCreate(savedInstanceState); } @Override protected void onDestroy() { Log.d(TAG, "onDestroy()"); super.onDestroy(); } @Override protected void onPause() { Log.d(TAG, "onPause()"); super.onPause(); } @Override protected void onPostCreate(Bundle savedInstanceState) { Log.d(TAG, "onPostCreate(" + savedInstanceState + ")"); super.onPostCreate(savedInstanceState); } @Override protected void onPostResume() { Log.d(TAG, "onPostResume()"); super.onPostResume(); } @Override protected void onRestart() { Log.d(TAG, "onRestart()"); super.onRestart(); } @Override protected void onRestoreInstanceState(Bundle savedInstanceState) { Log.d(TAG, "onRestoreInstanceState(" + savedInstanceState + ")"); super.onRestoreInstanceState(savedInstanceState); } @Override protected void onResume() { Log.d(TAG, "onResume()"); super.onResume(); } @Override protected void onStart() { Log.d(TAG, "onStart()"); super.onStart(); } @Override protected void onStop() { Log.d(TAG, "onStop()"); super.onStop(); } @Override protected void onUserLeaveHint() { Log.d(TAG, "onUserLeaveHint()"); super.onUserLeaveHint(); } } Nothing (of the above) is written to the log.

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• Watching a variable for changes without polling.

  - by milkfilk

  I'm using a framework called Processing which is basically a Java applet. It has the ability to do key events because Applet can. You can also roll your own callbacks of sorts into the parent. I'm not doing that right now and maybe that's the solution. For now, I'm looking for a more POJO solution. So I wrote some examples to illustrate my question. Please ignore using key events on the command line (console). Certainly this would be a very clean solution but it's not possible on the command line and my actual app isn't a command line app. In fact, a key event would be a good solution for me but I'm trying to understand events and polling beyond just keyboard specific problems. Both these examples flip a boolean. When the boolean flips, I want to fire something once. I could wrap the boolean in an Object so if the Object changes, I could fire an event too. I just don't want to poll with an if() statement unnecessarily. import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; /* * Example of checking a variable for changes. * Uses dumb if() and polls continuously. */ public class NotAvoidingPolling { public static void main(String[] args) { boolean typedA = false; String input = ""; System.out.println("Type 'a' please."); while (true) { InputStreamReader isr = new InputStreamReader(System.in); BufferedReader br = new BufferedReader(isr); try { input = br.readLine(); } catch (IOException ioException) { System.out.println("IO Error."); System.exit(1); } // contrived state change logic if (input.equals("a")) { typedA = true; } else { typedA = false; } // problem: this is polling. if (typedA) System.out.println("Typed 'a'."); } } } Running this outputs: Type 'a' please. a Typed 'a'. On some forums people suggested using an Observer. And although this decouples the event handler from class being observed, I still have an if() on a forever loop. import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.Observable; import java.util.Observer; /* * Example of checking a variable for changes. * This uses an observer to decouple the handler feedback * out of the main() but still is polling. */ public class ObserverStillPolling { boolean typedA = false; public static void main(String[] args) { // this ObserverStillPolling o = new ObserverStillPolling(); final MyEvent myEvent = new MyEvent(o); final MyHandler myHandler = new MyHandler(); myEvent.addObserver(myHandler); // subscribe // watch for event forever Thread thread = new Thread(myEvent); thread.start(); System.out.println("Type 'a' please."); String input = ""; while (true) { InputStreamReader isr = new InputStreamReader(System.in); BufferedReader br = new BufferedReader(isr); try { input = br.readLine(); } catch (IOException ioException) { System.out.println("IO Error."); System.exit(1); } // contrived state change logic // but it's decoupled now because there's no handler here. if (input.equals("a")) { o.typedA = true; } } } } class MyEvent extends Observable implements Runnable { // boolean typedA; ObserverStillPolling o; public MyEvent(ObserverStillPolling o) { this.o = o; } public void run() { // watch the main forever while (true) { // event fire if (this.o.typedA) { setChanged(); // in reality, you'd pass something more useful notifyObservers("You just typed 'a'."); // reset this.o.typedA = false; } } } } class MyHandler implements Observer { public void update(Observable obj, Object arg) { // handle event if (arg instanceof String) { System.out.println("We received:" + (String) arg); } } } Running this outputs: Type 'a' please. a We received:You just typed 'a'. I'd be ok if the if() was a NOOP on the CPU. But it's really comparing every pass. I see real CPU load. This is as bad as polling. I can maybe throttle it back with a sleep or compare the elapsed time since last update but this is not event driven. It's just less polling. So how can I do this smarter? How can I watch a POJO for changes without polling? In C# there seems to be something interesting called properties. I'm not a C# guy so maybe this isn't as magical as I think. private void SendPropertyChanging(string property) { if (this.PropertyChanging != null) { this.PropertyChanging(this, new PropertyChangingEventArgs(property)); } }

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• Design Question - how do you break the dependency between classes using an interface?

  - by Seth Spearman

  Hello, I apologize in advance but this will be a long question. I'm stuck. I am trying to learn unit testing, C#, and design patterns - all at once. (Maybe that's my problem.) As such I am reading the Art of Unit Testing (Osherove), and Clean Code (Martin), and Head First Design Patterns (O'Reilly). I am just now beginning to understand delegates and events (which you would see if you were to troll my SO questions of recent). I still don't quite get lambdas. To contextualize all of this I have given myself a learning project I am calling goAlarms. I have an Alarm class with members you'd expect (NextAlarmTime, Name, AlarmGroup, Event Trigger etc.) I wanted the "Timer" of the alarm to be extensible so I created an IAlarmScheduler interface as follows... public interface AlarmScheduler { Dictionary<string,Alarm> AlarmList { get; } void Startup(); void Shutdown(); void AddTrigger(string triggerName, string groupName, Alarm alarm); void RemoveTrigger(string triggerName); void PauseTrigger(string triggerName); void ResumeTrigger(string triggerName); void PauseTriggerGroup(string groupName); void ResumeTriggerGroup(string groupName); void SetSnoozeTrigger(string triggerName, int duration); void SetNextOccurrence (string triggerName, DateTime nextOccurrence); } This IAlarmScheduler interface define a component that will RAISE an alarm (Trigger) which will bubble up to my Alarm class and raise the Trigger Event of the alarm itself. It is essentially the "Timer" component. I have found that the Quartz.net component is perfectly suited for this so I have created a QuartzAlarmScheduler class which implements IAlarmScheduler. All that is fine. My problem is that the Alarm class is abstract and I want to create a lot of different KINDS of alarm. For example, I already have a Heartbeat alarm (triggered every (int) interval of minutes), AppointmentAlarm (triggered on set date and time), Daily Alarm (triggered every day at X) and perhaps others. And Quartz.NET is perfectly suited to handle this. My problem is a design problem. I want to be able to instantiate an alarm of any kind without my Alarm class (or any derived classes) knowing anything about Quartz. The problem is that Quartz has awesome factories that return just the right setup for the Triggers that will be needed by my Alarm classes. So, for example, I can get a Quartz trigger by using TriggerUtils.MakeMinutelyTrigger to create a trigger for the heartbeat alarm described above. Or TriggerUtils.MakeDailyTrigger for the daily alarm. I guess I could sum it up this way. Indirectly or directly I want my alarm classes to be able to consume the TriggerUtils.Make* classes without knowing anything about them. I know that is a contradiction, but that is why I am asking the question. I thought about putting a delegate field into the alarm which would be assigned one of these Make method but by doing that I am creating a hard dependency between alarm and Quartz which I want to avoid for both unit testing purposes and design purposes. I thought of using a switch for the type in QuartzAlarmScheduler per here but I know it is bad design and I am trying to learn good design. If I may editorialize a bit. I've decided that coding (predefined) classes is easy. Design is HARD...in fact, really hard and I am really fighting feeling stupid right now. I guess I want to know if you really smart people took a while to really understand and master this stuff or should I feel stupid (as I do) because I haven't grasped it better in the couple of weeks/months I have been studying. You guys are awesome and thanks in advance for your answers. Seth

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• Where do I start ?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be learning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• Is there any better way for creating a dynamic HTML table without using any javascript library like

  - by piemesons

  Dont worry we dont need to find out any bug in this code.. Its working perfectly.:-P My boss came to me and said "Hey just tell me whats the best of way of writing code for a dynamic HTML table (add row, delete row, update row).No need to add any CSS. Just javascript. No Jquery library etc. I was confused that in the middle of the project why he asking for some stupid exercise like this. What ever i wrote the following code and mailed him and after 15 mins i got a mail from him. " I was expecting much better code from a guy like you. Anyways good job monkey.(And with a picture of monkey as attachment.) thats was the mail. Line by line. I want to reply him but before that i want to know about the quality of my code. Is this really shitty...!!! Or he was just making fun of mine. I dont think that code is really shitty. Still correct me if you can.Code is working perfectly fine. Just copy paste it in a HTML file. <html> <head> <title> Exercise CSS </title> <script type="text/javascript"> function add_row() { var table = document.getElementById('table'); var rowCount = table.rows.length; var row = table.insertRow(rowCount); var cell1 = row.insertCell(0); var element1 = document.createElement("input"); element1.type = "text"; cell1.appendChild(element1); var cell2 = row.insertCell(1); var element2 = document.createElement("input"); element2.type = "text"; cell2.appendChild(element2); var cell3 = row.insertCell(2); cell3.innerHTML = ' <span onClick="edit(this)">Edit</span>/<span onClick="delete_row(this)">Delete</span>'; cell3.setAttribute("style", "display:none;"); var cell4 = row.insertCell(3); cell4.innerHTML = '<span onClick="save(this)">Save</span>'; } function save(e) { var elTableCells = e.parentNode.parentNode.getElementsByTagName("td"); elTableCells[0].innerHTML=elTableCells[0].firstChild.value; elTableCells[1].innerHTML=elTableCells[1].firstChild.value; elTableCells[2].setAttribute("style", "display:block;"); elTableCells[3].setAttribute("style", "display:none;"); } function edit(e) { var elTableCells = e.parentNode.parentNode.getElementsByTagName("td"); elTableCells[0].innerHTML='<input type="text" value="'+elTableCells[0].innerHTML+'">'; elTableCells[1].innerHTML='<input type="text" value="'+elTableCells[1].innerHTML+'">'; elTableCells[2].setAttribute("style", "display:none;"); elTableCells[3].setAttribute("style", "display:block;"); } function delete_row(e) { e.parentNode.parentNode.parentNode.removeChild(e.parentNode.parentNode); } </script> </head> <body > <div id="display"> <table id='table'> <tr id='id'> <td> Piemesons </td> <td> 23 </td> <td > <span onClick="edit(this)">Edit</span>/<span onClick="delete_row(this)">Delete</span> </td> <td style="display:none;"> <span onClick="save(this)">Save</span> </td> </tr> </table> <input type="button" value="Add new row" onClick="add_row();" /> </div> </body>

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• Editing a Gridview row with drop-down lists gets too wide - how can I use popup panels instead?

  - by David

  I have a series of GridViews in a Tab Panel - databound to a generic List of Business Objects. The columns in the Gridview are all similar to the following: <asp:TemplateField HeaderText="Company" SortExpression="Company.ShortName"> <ItemTemplate> <asp:Label ID="lblCompany" runat="server" Text='<%# Bind("Company.ShortName") %>'></asp:Label> </ItemTemplate> <EditItemTemplate> <asp:DropDownList ID="ddlCompany" runat="server"></asp:DropDownList> </EditItemTemplate> </asp:TemplateField> The GridView generates the "Edit" link at the beginning of the row, all the events fire ok. The problem is that the data is getting long. When in 'display mode', it's fine because the GridView control is smart enough to break some text into multiple lines (in particular Project, Title and Worker names can get pretty long). The problem come in editing mode. Drop-down lists DON'T break entries into multiple lines (for obvious reasons). Going into Edit ode on a row in the Gridview can make the Griview expand horizontally to twice the screen size (blowing through the width limits in the Master page and CSS but that's only a related problem). What I need is something like the ModalPopup - but trying to tie it to an ID in an EditItemTemplate gives me errors when the page renders (because the 'ddlXXXX' doesn't exist at the time). In addition I don't know how to dynamically populate the panel so that I can get a response from it (like the ID of the Company they selected). I'm also trying to avoid javascript and would like this to be a 'pure' aspx/code-behind solution (for simplicity's sake among others). All the examples I find are of Modal Popups with the panels pre-defined. Even if it (the popup panel) were something like a list of checkboxes, it could be databound to the SortedList I have ready to go and an OK/Cancel button combination to accept or ignore things. I'm just not sure of what goes where. I'm open to suggestions. Thanks in advance. EDIT: Final solution looks as follows: <asp:TemplateField HeaderText="Company" SortExpression="Company.ShortName"> <ItemTemplate> <asp:Label ID="lblCompany" runat="server" Text='<%# Bind("Company.ShortName") %>'></asp:Label> </ItemTemplate> <EditItemTemplate> <asp:LinkButton ID="lnkCompany" runat="server" Text='<%# Bind("Company.ShortName") %>'></asp:LinkButton> <asp:Panel ID="pnlCompany" runat="server" style="display:none"> <div> <asp:DropDownList ID="ddlCompany" runat="server" ></asp:DropDownList> <br/> <asp:ImageButton ID="btnOKCo" runat="server" ImageUrl="~/Images/greencheck.gif" OnCommand="PopupButton_Command" CommandName="SelectCO" /> <asp:ImageButton ID="btnCxlCo" runat="server" ImageUrl="~/Images/RedX.gif" /> </div> </asp:Panel> <cc1:ModalPopupExtender ID="mpeCompany" runat="server" TargetControlID="lnkCompany" PopupControlID="pnlCompany" BackgroundCssClass="modalBackground" CancelControlID="btnCxlCo" DropShadow="true" PopupDragHandleControlID="pnlCompany" /> </EditItemTemplate> </asp:TemplateField> And in the code-behind, lstIDLabor is the generic List of data lines (of which Company is one of the properties that is also a business object) that is bound to the GridView: Sub PopupButton_Command(ByVal sender As Object, ByVal e As CommandEventArgs) Dim intRow As Integer Dim intVal As Integer RestoreFromSessionVariables() Select Case e.CommandName Case "SelectCO" intRow = grdIDCostLabor.EditIndex Dim ddlCo As DropDownList = CType(grdIDCost.Rows(intRow).FindControl("ddlCompany"), DropDownList) intVal = ddlCo.SelectedValue lstIDLabor(intRow).CompanyID = intVal lstIDLabor(intRow).Company = Company.Read(intVal) Case Else ' End Select MakeSessionVariables() BindGrids() End Sub

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• How best to modernize the 2002-era J2EE app?

  - by user331465

  I have this friend.... I have this friend who works on a java ee application (j2ee) application started in the early 2000's. Currently they add a feature here and there, but have a large codebase. Over the years the team has shrunk by 70%. [Yes, the "i have this friend is". It's me, attempting to humorously inject teenage high-school counselor shame into the mix] Java, Vintage 2002 The application uses EJB 2.1, struts 1.x, DAO's etc with straight jdbc calls (mixture of stored procedures and prepared statements). No ORM. For caching they use a mixture of OpenSymphony OSCache and a home-grown cache layer. Over the last few years, they have spent effort to modernize the UI using ajax techniques and libraries. This largely involves javascript libaries (jquery, yui, etc). Client Side On the client side, the lack of upgrade path from struts1 to struts2 discouraged them from migrating to struts2. Other web frameworks became popular (wicket, spring , jsf). Struts2 was not the "clear winner". Migrating all the existing UI from Struts1 to Struts2/wicket/etc did not seem to present much marginal benefit at a very high cost. They did not want to have a patchwork of technologies-du-jour (subsystem X in Struts2, subsystem Y in Wicket, etc.) so developer write new features using Struts 1. Server Side On the server side, they looked into moving to ejb 3, but never had a big impetus. The developers are all comfortable with ejb-jar.xml, EJBHome, EJBRemote, that "ejb 2.1 as is" represented the path of least resistance. One big complaint about the ejb environment: programmers still pretend "ejb server runs in separate jvm than servlet engine". No app server (jboss/weblogic) has ever enforced this separation. The team has never deployed the ejb server on a separate box then the app server. The ear file contains multiple copies of the same jar file; one for the 'web layer' (foo.war/WEB-INF/lib) and one for the server side (foo.ear/). The app server only loads one jar. The duplications makes for ambiguity. Caching As for caching, they use several cache implementations: OpenSymphony cache and a homegrown cache. Jgroups provides clustering support Now What? The question: The team currently has spare cycles to to invest in modernizing the application? Where would the smart investor spend them? The main criteria: 1) productivity gains. Specifically reducing the time to develope new subsystems features and reduced maintenance. 2) performance/scalability. They do not care about fashion or techno-du-jour street cred. What do you all recommend? On the persistence side Switch everything (or new development only) to JPA/JPA2? Straight hibernate? Wait for Java EE 6? On the client/web-framework side: Migrate (some or all) to struts2? wicket? jsf/jsf2? As for caching: terracotta? ehcache? coherence? stick with what they have? how best to take advantage of the huge heap sizes that the 64-bit jvms offer? Thanks in advance.

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• linux script, standard directory locations.

  - by Thingomy

  I am trying to write a bash script to do a task, I have done pretty well so far, and have it working to an extent, but I want to set it up so it's distributable to other people, and will be opening it up as open source, so I want to start doing things the "conventional" way. Unfortunately I'm not all that sure what the conventional way is. Ideally I want a link to an in depth online resource that discusses this and surrounding topics in depth, but I'm having difficulty finding keywords that will locate this on google. At the start of my script I set a bunch of global variables that store the names of the dirs that it will be accessing, this means that I can modify the dir's quickly, but this is programming shortcuts, not user shortcuts, I can't tell the users that they have to fiddle with this stuff. Also, I need for individual users' settings not to get wiped out on every upgrade. Questions: Name of settings folder: ~/.foo/ -- this is well and good, but how do I keep my working copy and my development copy separate? tweek the reference in the source of the dev version? If my program needs to maintain and update library of data (gps tracklog data in this case) where should this directory be? the user will need to access some of this data, but it's mostly for internal use. I personally work in cygwin, and I like to keep this data on separate drive, so the path is wierd, I suspect many users could find this. for a default however I'm thinking ~/gpsdata/ -- would this be normal, or should I hard code a system that ask the user at first run where to put it, and stores this in the settings folder? whatever happens I'm going ot have to store the directory reference in a file in the settings folder. The program needs a data "inbox" that is a folder that the user can dump files, then run the script to process these files. I was thinking ~/gpsdata/in/ ?? though there will always be an option to add a file or folder to the command line to use that as well (it processed files all locations listed, including the "inbox") Where should the script its self go? it's already smart enough that it can create all of it's ancillary/settings files (once I figure out the "correct" directory) if run with "./foo --setup" I could shove it in /usr/bin/ or /bin or ~/.foo/bin (and add that to the path) what's normal? I need to store login details for a web service that it will connect to (using curl -u if it matters) plan on including a setting whereby it asks for a username and password every execution, but it currently stores it plane text in a file in ~/.foo/ -- I know, this is not good. The webservice (osm.org) does support oauth, but I have no idea how to get curl to use it -- getting curl to speak to the service in the first place was a hack. Is there a simple way to do a really basic encryption on a file like this to deter idiots armed with notepad? Sorry for the list of questions, I believe they are closely related enough for a single post. This is all stuff that stabbing at, but would like clarification/confirmation over.

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• Event handle in drop-down menu.

  - by QLiu

  Hello fellows, I am trying to develop a dynamic drop down menu by a customized widget style The custom widget has two main features: Read user's location cookies variable to set the proper contact phone number in the CP pages When users select on the drop down menu, it triggers onChange event, it re-select the contact phone number based on users' selections, but it won't reset the location cookies. My widgets conatins two files: Controller.php: Simply one, it uses to handle get cookies variables class serial extends Widget { function __construct() { parent::__construct(); } function generateWidgetInformation() { $this->info['notes'] = "Serial Number search Box"; } function getData() { //Get cookies code will go here, and pass to view.php $this->data['locale'] = 'gb';// for test purpose now } } view.php is about Presentation layer contains HTML, which get the data from my controller <div style="border: 1px solid black; display: block;" id="<?=$this->instanceID;?>"></div> <script>locale2contact('<?=$this->data['locale']?>', '<?=$this->instanceID;?>');</script> And then the Javascript function, call locale2contact var element_id =''; //Define Global Variables, //Receive the cookies locale, and instance id from view.php function locale2contact(locale, instance_id) { var details = ''; this.element_id=instance_id; //assing the instance id into global variable // alert(instance_id); //Check whether we got the instance id from view files if (locale == 'gb') details = 'UK Contact Details<br>' + build_dropdown(locale); else if (locale == 'fr') details = 'French Contact Details<br>'+build_dropdown(locale); else if (locale == 'be') details = 'Belgian Contact Details<br>'+ build_dropdown(locale); else details = 'Unknown Contact Detail'; writeContactInfo(details); } //Build the drop down menu with pre-selected option by using cookies. function build_dropdown(locale) { var dropdown = '<select onChange=changeContactInfo(this.options[selectedIndex].text)>'; dropdown += '<option' + (locale == 'gb' ? ' selected' : '') + '>UK</option>'; dropdown += '<option' + (locale == 'be' ? ' selected' : '') + '>Belgium</option>'; dropdown += '</select>'; return dropdown; } // Not smart way in here, once the people select the drop down box, it reselect the drop down menu and reset the contact info function changeContactInfo(selected) { var details =''; //alert(this.element_id); //alert(locale); if (selected == 'UK') details = 'UK Contact Details<br>' + build_dropdown2(selected); else if (selected == 'fr') details = 'French Contact Details<br>'+ build_dropdown2(selected); else if (selected == 'Belgium') details = 'Belgian Contact Details<br>'+ build_dropdown2(selected); else details = 'Unknown Contact Detail'; writeContactInfo(details); } //Build the drop down menu function build_dropdown2(selected) { var dropdown = '<select onChange=changeContactInfo(this.options[selectedIndex].text)>'; dropdown += '<option' + (selected == 'UK' ? ' selected' : '') + '>UK</option>'; dropdown += '<option' + (selected == 'Belgium' ? ' selected' : '') + '>Belgium</option>'; dropdown += '</select>'; return dropdown; } //Back to view function writeContactInfo(details) { document.getElementById(this.element_id).innerHTML = details; //update the instance field in view } Javascript function is not efficient. As you see, I got two similar duplicate functions to handle events. Users go to the page, the widget read the cookies variable to display contact info (locale2contact)and preselect the drop-down menu (function build_dropdown) If users select the drop down menu, the displya contact info change (function changeContactInfo), and then I need to rebuild the drop down menu with user previously selection (function build_dropdown2). I am looking for best practices for adding this functionality to RightNow widget. Thank you. I really do not like the way i am doing now. It works; but the code looks bad.

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• How do I learn algorithms?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• Is there a potential for resource leak/double free here?

  - by nhed

  The following sample (not compiled so I won't vouch for syntax) pulls two resources from resource pools (not allocated with new), then "binds" them together with MyClass for the duration of a certain transaction. The transaction, implemented here by myFunc, attempts to protect against leakage of these resources by tracking their "ownership". The local resource pointers are cleared when its obvious that instantiation of MyClass was successful. The local catch, as well as the destructor ~MyClass return the resources to their pool (double-frees are protected by teh above mentioned clearing of the local pointers). Instantiation of MyClass can fail and result in an exception at two steps (1) actual memory allocation, or (2) at the constructor body itself. I do not have a problem with #1, but in the case of #2, if the exception is thrown AFTER m_resA & m_resB were set. Causing both the ~MyClass and the cleanup code of myFunc to assume responsibility for returning these resources to their pools. Is this a reasonable concern? Options I have considered, but didn't like: Smart pointers (like boost's shared_ptr). I didn't see how to apply to a resource pool (aside for wrapping in yet another instance). Allowing double-free to occur at this level but protecting at the resource pools. Trying to use the exception type - trying to deduce that if bad_alloc was caught that MyClass did not take ownership. This will require a try-catch in the constructor to make sure that any allocation failures in ABC() ...more code here... wont be confused with failures to allocate MyClass. Is there a clean, simple solution that I have overlooked? class SomeExtResourceA; class SomeExtResourceB; class MyClass { private: // These resources come out of a resource pool not allocated with "new" for each use by MyClass SomeResourceA* m_resA; SomeResourceB* m_resB; public: MyClass(SomeResourceA* resA, SomeResourceB* resB): m_resA(resA), m_resB(resB) { ABC(); // ... more code here, could throw exceptions } ~MyClass(){ if(m_resA){ m_resA->Release(); } if(m_resB){ m_resB->Release(); } } }; void myFunc(void) { SomeResourceA* resA = NULL; SomeResourceB* resB = NULL; MyClass* pMyInst = NULL; try { resA = g_pPoolA->Allocate(); resB = g_pPoolB->Allocate(); pMyInst = new MyClass(resA,resB); resA=NULL; // ''ownership succesfully transfered to pMyInst resB=NULL; // ''ownership succesfully transfered to pMyInst // Do some work with pMyInst; ...; delete pMyInst; } catch (...) { // cleanup // need to check if resA, or resB were allocated prior // to construction of pMyInst. if(resA) resA->Release(); if(resB) resB->Release(); delete pMyInst; throw; // rethrow caught exception } }

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• C++ Optimize if/else condition

  - by Heye

  I have a single line of code, that consumes 25% - 30% of the runtime of my application. It is a less-than comparator for an std::set (the set is implemented with a Red-Black-Tree). It is called about 180 Million times within 52 seconds. struct Entry { const float _cost; const long _id; // some other vars Entry(float cost, float id) : _cost(cost), _id(id) { } }; template<class T> struct lt_entry: public binary_function <T, T, bool> { bool operator()(const T &l, const T &r) const { // Most readable shape if(l._cost != r._cost) { return r._cost < l._cost; } else { return l._id < r._id; } } }; The entries should be sorted by cost and if the cost is the same by their id. I have many insertions for each extraction of the minimum. I thought about using Fibonacci-Heaps, but I have been told that they are theoretically nice, but suffer from high constants and are pretty complicated to implement. And since insert is in O(log(n)) the runtime increase is nearly constant with large n. So I think its okay to stick to the set. To improve performance I tried to express it in different shapes: return l._cost < r._cost || r._cost > l._cost || l._id < r._id; return l._cost < r._cost || (l._cost == r._cost && l._id < r._id); Even this: typedef union { float _f; int _i; } flint; //... flint diff; diff._f = (l._cost - r._cost); return (diff._i && diff._i >> 31) || l._id < r._id; But the compiler seems to be smart enough already, because I haven't been able to improve the runtime. I also thought about SSE but this problem is really not very applicable for SSE... The assembly looks somewhat like this: movss (%rbx),%xmm1 mov $0x1,%r8d movss 0x20(%rdx),%xmm0 ucomiss %xmm1,%xmm0 ja 0x410600 <_ZNSt8_Rb_tree[..]+96> ucomiss %xmm0,%xmm1 jp 0x4105fd <_ZNSt8_Rb_[..]_+93> jne 0x4105fd <_ZNSt8_Rb_[..]_+93> mov 0x28(%rdx),%rax cmp %rax,0x8(%rbx) jb 0x410600 <_ZNSt8_Rb_[..]_+96> xor %r8d,%r8d I have a very tiny bit experience with assembly language, but not really much. I thought it would be the best (only?) point to squeeze out some performance, but is it really worth the effort? Can you see any shortcuts that could save some cycles? The platform the code will run on is an ubuntu 12 with gcc 4.6 (-stl=c++0x) on a many-core intel machine. Only libraries available are boost, openmp and tbb. I am really stuck on this one, it seems so simple, but takes that much time. I have been crunching my head since days thinking how I could improve this line... Can you give me a suggestion how to improve this part, or is it already at its best?

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• SQL: Using a CASE Statement to update 1000 rows at once

  - by SoLoGHoST

  Ok, I would like to use a CASE STATEMENT for this, but I am lost with this. Basically, I need to update a ton of rows, but just on the "position" column. I need to update all "position" values from 0 - count(position) for each id_layout_position column per id_layout column. OK, here is a pic of what the table looks like: Now let's say I delete the circled row, this will remove position = 2 and give me: 0, 1, 3, 5, 6, 7, and 4. But I want to add something at the end now and make sure that it has the last possible position, but the positions are already messed up, so I need to reorder them like so before I insert the new row: 0, 1, 2, 3, 4, 5, 6. But it must be ordered by lowest first. So 0 stays at 0, 1 stays at 1, 3 gets changed to 2, the 4 at the end gets changed to a 3, 5 gets changed to 4, 6 gets changed to 5, and 7 gets changed to 6. Hopefully you guys get the picture now. I'm completely lost here. Also, note, this table is tiny compared to how fast it can grow in size, so it needs to be able to do this FAST, thus I was thinking on the CASE STATEMENT for an UPDATE QUERY. Here's what I got for a regular update, but I don't wanna throw this into a foreach loop, as it would take forever to do it. I'm using SMF (Simple Machines Forums), so it might look a little different, but the idea is the same, and CASE statements are supported... $smcFunc['db_query']('', ' UPDATE {db_prefix}dp_positions SET position = {int:position} WHERE id_layout_position = {int:id_layout_position} AND id_layout = {int:id_layout}', array( 'position' => $position++, 'id_layout_position' => (int) $id_layout_position, 'id_layout' => (int) $id_layout, ) ); Anyways, I need to apply some sort of CASE on this so that I can auto-increment by 1 all values that it finds and update to the next possible value. I know I'm doing this wrong, even in this QUERY. But I'm totally lost when it comes to CASES. Here's an example of a CASE being used within SMF, so you can see this and hopefully relate: $conditions = ''; foreach ($postgroups as $id => $min_posts) { $conditions .= ' WHEN posts >= ' . $min_posts . (!empty($lastMin) ? ' AND posts <= ' . $lastMin : '') . ' THEN ' . $id; $lastMin = $min_posts; } // A big fat CASE WHEN... END is faster than a zillion UPDATE's ;). $smcFunc['db_query']('', ' UPDATE {db_prefix}members SET id_post_group = CASE ' . $conditions . ' ELSE 0 END' . ($parameter1 != null ? ' WHERE ' . (is_array($parameter1) ? 'id_member IN ({array_int:members})' : 'id_member = {int:members}') : ''), array( 'members' => $parameter1, ) ); Before I do the update, I actually have a SELECT which throws everything I need into arrays like so: $disabled_sections = array(); $positions = array(); while ($row = $smcFunc['db_fetch_assoc']($request)) { if (!isset($disabled_sections[$row['id_group']][$row['id_layout']])) $disabled_sections[$row['id_group']][$row['id_layout']] = array( 'info' => $module_info[$name], 'id_layout_position' => $row['id_layout_position'] ); // Increment the positions... if (!is_null($row['position'])) { if (!isset($positions[$row['id_layout']][$row['id_layout_position']])) $positions[$row['id_layout']][$row['id_layout_position']] = 1; else $positions[$row['id_layout']][$row['id_layout_position']]++; } else $positions[$row['id_layout']][$row['id_layout_position']] = 0; } Thanks, I know if anyone can help me here it's definitely you guys and gals... Anyways, here is my question: How do I use a CASE statement in the first code example, so that I can update all of the rows in the position column from 0 - total # of rows found, that have that id_layout value and that id_layout_position value, and continue this for all different id_layout values in that table? Can I use the arrays above somehow? I'm sure I'll have to use the id_layout and id_layout_position values for this right? But how can I do this? Ok, guy, I get an error, saying "Hacking Attempt" with the following code: // Updating all positions in here. $smcFunc['db_query']('', ' SET @pos = 0; UPDATE {db_prefix}dp_positions SET position=@pos:=@pos+1 ORDER BY id_layout_position, position', array( ) ); Am I doing something wrong? Perhaps SMF has safeguards against this approach?? Perhaps I need to use a CASE STATEMENT instead?

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