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  • Why does the heat production increase as the clockrate of a CPU increases?

    - by Nils
    This is probably a bit off-topic, but the whole multi-core debate got me thinking. It's much easier to produce two cores (in one package) then speeding up one core by a factor of two. Why exactly is this? I googled a bit, but found mostly very imprecise answers from over clocking boards which do not explain the underlying Physics. The voltage seems to have the most impact (quadratic), but do I need to run a CPU at higher voltage if I want a faster clock rate? Also I like to know why exactly (and how much) heat a semiconductor circuit produces when it runs at a certain clock speed.

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  • CentOS drive mapping? [on hold]

    - by DroidOS
    This is the first time I am posting on this particular StackExchange forum and I hope that I am using the right one for the present question. Briefly, this is what I need to do I am running a web service where users can, amongst other things, upload and store files on the server. What I want to do is to hive off user file storage to a different location so my server (CentOS 64 bit) can concentrate on what it does best - server side scripting and database management. As things stand all user files go into subdirectories in a folder called stash that lies above DOC_ROOT. What I would like to do is Transparently detect all attempts to read/write to stash/sub_folder and get/set file data on a remote server - ideally the latter would be one which replicates files like a CDN so they can be delivered from the closest/fastest location based on where the user's location. Even nicer would be if for all read accesses I could provide a URL that allows the user's browser to fetch the relevant file directly without having to funnel them via my server. I am a relative newbie when it comes to this sort of thing so I hope that I have phrased this question adequately well. From the little searching I done I gathered that WebDAV can be used to map drives to a different location on the web so perhaps that is a starting point. But if that will work I need to Establish how to get WebDAV up and running on my CentOS 64 bit server. Ideally, identify a service that allows this kind of file storage and provides an API I can use in my own scripting. I'd much appreciate any help with this.

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  • Left click and enter not working

    - by user1981338
    Sometimes when I turn on my homemade desktop computer (running 64-bit Windows 7), the left mouse click and enter key doesn't work. They work well in BIOS, as well as on the Windows 7 BCD and login screen. Usually, restarting the computer solves the problem. Why does this keep happening? I've tried: Using other USB ports Refreshing, repairing and reinstalling drivers Changing mouse settings Refreshing mouse profiles My keyboard is a Logitech G510, and my mouse is a Razer Lanchesis 5600. Both work without problems in Ubuntu 12.04 and Windows 8.1 Preview, and I've been using both on my 64-bit Windows 7 homemade desktop without problems for about a year and a half. I encountered the problems yesterday.

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  • Which is the best way to catch an expiring domain name? [closed]

    - by newspeak
    I know a similar question has been asked, but I really don't know what to do. There is this .com domain which is currently on redemption period and should likely be available again within a month. I was wondering which is the best way to get it at a reasonable price. I don't think it's a highly valuable domain, it shows to have very bad ranking and has 0 exact same searches according to adwords. Why it is valuable to me is very simple: I have a project responding to this name. I already own the .net domain and would love to have the .com. I discovered the domain was going to be available thanks to an email I received by a backorder site. I did some research and these guys have a bad reputation on the web. I did further research and found that more reputable (at least in theory) companies should be the likes of snapnames, pool, namejet, godaddy, etc. I am a bit suspicious using these drop cathing services: What if they shill bids? What if they make it go into auction even if I'm the only person interested? What if I raise attention and interest to the domain by backordering? I just would rather wait for it to be deleted and available again to register it manually. It is really not an interesting domain name, and I don't think anyone would care to have it. But what if the domain is already being watched by the domain industry sharks? I did a whois research and my desired domain nameserves point to domcollect.com, which appears to be an auction site. What if I decide to wait for manual registration and I miss the chance to get it? I'm willing to spend the 60/70$ fees these sites require, but not really more than that. Suggestions? Thank you very much. I'm a bit confused and undecided.

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  • Battery life low on notebook using ubuntu 11.10 vs. windows 7

    - by les
    Im using a brand new Dell XPS notebook (bought mar 2012) which has 4.5 hrs battery life using a 6 cell battery-when i use windows 7. The machine uses an Intel core 17 2670qm processor, and a 64 bit operating system. I downloaded Ubuntu 11.10 and installed it on a USB drive, which is how i use it. I still have Windows 7 on the machine. When the machine is booting up I hit F12, and run Ubuntu from the flash drive instead of the machine booting Windows, as it normally would. On the Ubuntu menu, on the top right area, there is a battery menu, which shows how long to charge battery, or how much life left etc..with a fully charged battery the most Ubuntu will give me is 1.5 hrs. I've adjusted all power setting etc by clicking on the battery meter where i can make these adjustments, and have even turned down the brightness on the monitor. I've read through these questions here, and a user wrote to install Ubuntu 12(?)(the alpha version) when it's out this month(april), and this has better power management. Other forums (Ubuntu wiki) state that windows 7 controls power management effectively because it's configured to work with the hardware. I'd like to install Ubuntu and wipe windows but can't because of this issue. I need my notebook to go hours, not an hour and a bit. Can anybody recommend possibly a good software to use, that will work with the machines bios under Ubuntu? Another thought of mine, is- since I didn't yet wipe windows off my hard disk, is windows still possibly controlling the power mgmt aspect on the machine? I've thought of calling tech support at Dell and asking for help there, maybe Dell has something (a tweak?), I can download that'll work under Ubuntu. Looking forward to any help/suggestions i can get here, i'm really stuck on this..

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  • Why Virtualbox VDI doubles the space of the VM hard disk?

    - by logoff
    I have one Xubuntu 12.10 64 bit Virtualbox VM on a Windows 7 64 bit host. It has one dynamic allocated hard disk with VDI format with maximum capacity of 20GB. If I use a command df -h in the VM I get that 5.3GB are in use in th main partition. I have only 2 partitions, one for the ext4 hard disk and another with 512MB of swap. I have no snapshots. The VDI file of this VM has 10.7GB. It is normal this difference of space? It is caused because the VDI format?

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  • SQL Server 2012 Express LocalDB &ndash; How to get started

    - by krislankford
    As many of you aware, SQL Server can be a bit of a pig when it comes to system resources on your development machine. As part of the 2012 products Microsoft has added SQL Server 2012 Express LocalDB which is a happy medium for myself when thinking about having to install a full blown SQL Server on my box. This however does not work in all cases for all development but if you are doing web or local client development then it should suffice. On the other hand, if you are working with technologies like SharePoint or trying to run Team Foundation Server on your local box then you will be out of luck while using LocalDB. To start of with, the localDB setup is delivered and packaged with Visual Studio 2012 RC. If you want to get the stand-alone installer you can download it here in either the 32 or 64 bit flavors. Once you get it installed you can start using it right away in either Visual Studio 2010 or the new Visual Studio 2012 RC. To get started you can open the SQL Server object explorer in Visual Studio by clicking   the menu option View –> SQL Server Object Explorer. This will bring up to the navigation pane where you can add a SQL Server. Once you add the SQL Server you will be prompted with the “Connect to Server” dialog to enter the server for which you can use “(localdb)\v11.0”. Click connect and you should be connected to your localDB where you can create and manage databases from Visual Studio 2010, Visual Studio 2012 or SSMS. Once you have started creating databases here you can use the database projects in Visual Studio with these database as well as use the (localdb)\v11.0 server name inside your connections string information for your development environment. Hope this helps someone get started with SQL Server 2012 Express LocalDB! It provides a great balance for developing against SQL Server 2012.

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  • My laptop adapter has just faintly chirped like a cricket. Should I not plug it into my laptop again?

    - by Bloke
    The DC end that goes into the laptop was unplugged and the AC end was plugged into the mains (actually the plug sucks, so it could have been that it was...you know...just on the border. Getting and losing contact many times in a short amount of time if I moved the cable a bit) ...So one of these times that I just touched the cable, it did this chirping cricket sound and I unplugged it immediately. It did smell a bit weird, but I'm not sure if that's normal (due to heat or whatever).. So, should I be afraid of if? Can it kill my laptop if I try charging it? I only have around half an hour of battery left. Please help. Hope this is the right StackExchange site to ask. Thank you in advance

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  • Upgraded from ubuntu 12.04 to 12.10 issues

    - by ubuntu novice user
    I recently upgraded 12.04 to 12.10 ubuntu and then all hell broke loose. Being more specific, I have a Compaq machine and its hard disk is partitioned into 3 parts, so when I installed Ubuntu 10.04, I installed it in windows, since then have upgraded with each new ubuntu release via the update manager without any problems. I have installed the 64 bit versions. 12.10 downloaded via update manager, and initial downloading of packages was without problems, however, as it tried to install the packages, error messages appeared. The first was one about missing lib files, but I clicked to continue, since I am a relative novice on ubuntu. It continued, and during the restart process, when it was powering down, the computer hanged on the shutting down bit without rebooting for more than half an hour, so I manually shut down the machine and restarted it. Then a new error message appeared stating could not find disk, and I hit the manual fix option, and it now boots to an empty ubuntu desktop with my wallpaper but no launcher and the graphics appears as if this was put on a 640 x 480 resolution, and the screen no longer fits onto my 19" LCD. I had to use Ctrl-Alt-T to log out and then restart from there. How can I resolve this issue. Please help!

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  • Working in Germany (Munich) [closed]

    - by adri
    My husband and I are relocating to Munich in August (He's German). I have been looking for jobs online since I heard that software developers are in great demand. And by the looks of it, seems to be correct. There are lots of offers on line but I have a problem, my german is not spectacular. I would rate it as basic. Good to be a tourist but not good to write anything formal, not even my cover letter. So I was wondering how hard is really going to be to find a job for me with virtually no german (I'm studying, but good german is not going to happen over night). Also, would it be possible to secure a job before arriving to Germany? I have nearly 10 years of working experience developing software, mostly in .net (c#, vb, winForms, asp.net) but I also know java. 3 years experience as a team leader for groups of up to 8 people. In the last couple of years I've been working mostly on digitalization of documents (such as birth certificates and the like) but I'm more than willing to try other fields Also I speak English, Spanish, Italian, a bit of portuguese and of course a bit of german.

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  • Crunchbang asks for URIs to get build dependencies for php5 [closed]

    - by Koen027
    I'm trying to install PHP5, by compiling it myself. I'm doing this on Crunchbang Linux, version 11. Specifically, the version using the 3.2 kernel. Crunchbang 11 is based on Debian. This is a 64-bit Virtual machine, running on a 64-bit Win7 Professional. Using Virtualbox 4.2 This is my sources.list file: http://pastebin.com/rQJNwX7c When I try to do sudo apt-get build-dep php5, I get the following output: Reading package lists... Done Building dependency tree Reading state information... Done E: You must put some 'source' URIs in your sources.list I'm not sure what's going on here. Can anyone point out what's missing in my setup? Also, since I'm under 300 reputation on serverfault, I can't add the "crunchbang" tag.

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  • Outlook 2007 starts with minimized window

    - by astro46
    Outlook 2007, starts at boot, minimized: suddenly, as of 2 weeks ago, when I click on the taskbar icon (Outlook already started but minimized) what opens on screen is a tiny "window" the size of the close-minimize-restore buttons. I then have to move it down the screen, and drag the borders to bring it to full size, or, sometimes, clicking on the restore button maximizes the tiny window: then, for days, it starts either the same way or in some other small size, not the same as I left it. I would appreciate suggestions on how to repair this particular example of Outlook not remembering its setting? win7, 64 bit. outlook 2007 32 bit

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  • all USB "randomly" disconnect and reconnect

    - by teuneboon
    I'm having a weird issue currently: at seemingly random times(although it seems to happen mostly when USB is used a lot, ie downloading + uploading over my WiFi stick or viewing an HD video from my external hard-drive) all my USB devices disconnect and reconnect after a few seconds. This wouldn't be a HUGE problem if I didn't have to rely on my USB for my internet, because now every time this happens my internet, and with it stuff like remote desktop, crashes. I'm running Windows 8 Pro 64 bit with a Gigabyte 990FXA-D3 motherboard. Now the weird thing: I had the same problem with my previous pc, which had a different motherboard(I think it was an Asus M4A785TD-V EVO). I googled a bit and didn't really find anything about this, only found out I could check if something shows up in the Event Viewer, and I get this error there when the USB crashes: "A timeout occurred while waiting for the EHCI host controller Interrupt on Async Advance Doorbell response." If you require any extra information I'm happy to provide it.

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  • 2010 outlook stationery

    - by chris
    I have just installed Microsoft 2010 I am using the 'Outlook 2010' for my email program. For the past few years I have used Outlook Express and used the program quite well However with the Outlook 2010 I have not been able to find 2 functions that I was able to do on Outlook Express 1) OE I could press stationary and it would insert a BIT Map for me , however when I do stationary in Outlook 2010 it no longer allows me to insert the Bit map. 2) OE I created a rule that allowed me to copy emails into another folder , however in 2010 it only allows me to move as a rule and not the initial copy. Please could you explain how I may be able to use the same function in 2010?

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  • MSSQL 2005 Snapshot Agent Uses 100% CPU

    - by matth1jd
    When setting up a new subscription to a publication (transactional replication) from 64-bit SQL Server 2005 to 64-bit SQL Server 2005 the Snapshot Agent on the publisher consumes 100% of the CPU. I am using SSMS to create the new subscription. My initial impression is that this could be from row locking occurring during the generation of the snapshot but I have read that a concurrent snapshot is generated by default in SQL Server 2005, and that row locking shouldn't be a concern. As this is a production server I would like to be able to initialize replication without bringing the box to it's knees. Any suggestions would be helpful and appreciated.

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  • Converting AES encryption token code in C# to php

    - by joey
    Hello, I have the following .Net code which takes two inputs. 1) A 128 bit base 64 encoded key and 2) the userid. It outputs the AES encrypted token. I need the php equivalent of the same code, but dont know which corresponding php classes are to be used for RNGCryptoServiceProvider,RijndaelManaged,ICryptoTransform,MemoryStream and CryptoStream. Im stuck so any help regarding this would be really appreciated. using System; using System.Text; using System.IO; using System.Security.Cryptography; class AESToken { [STAThread] static int Main(string[] args) { if (args.Length != 2) { Console.WriteLine("Usage: AESToken key userId\n"); Console.WriteLine("key Specifies 128-bit AES key base64 encoded supplied by MediaNet to the partner"); Console.WriteLine("userId specifies the unique id"); return -1; } string key = args[0]; string userId = args[1]; StringBuilder sb = new StringBuilder(); // This example code uses the magic string “CAMB2B”. The implementer // must use the appropriate magic string for the web services API. sb.Append("CAMB2B"); sb.Append(args[1]); // userId sb.Append('|'); // pipe char sb.Append(System.DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ssUTC")); //timestamp Byte[] payload = Encoding.ASCII.GetBytes(sb.ToString()); byte[] salt = new Byte[16]; // 16 bytes of random salt RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); rng.GetBytes(salt); // the plaintext is 16 bytes of salt followed by the payload. byte[] plaintext = new byte[salt.Length + payload.Length]; salt.CopyTo(plaintext, 0); payload.CopyTo(plaintext, salt.Length); // the AES cryptor: 128-bit key, 128-bit block size, CBC mode RijndaelManaged cryptor = new RijndaelManaged(); cryptor.KeySize = 128; cryptor.BlockSize = 128; cryptor.Mode = CipherMode.CBC; cryptor.GenerateIV(); cryptor.Key = Convert.FromBase64String(args[0]); // the key byte[] iv = cryptor.IV; // the IV. // do the encryption ICryptoTransform encryptor = cryptor.CreateEncryptor(cryptor.Key, iv); MemoryStream ms = new MemoryStream(); CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write); cs.Write(plaintext, 0, plaintext.Length); cs.FlushFinalBlock(); byte[] ciphertext = ms.ToArray(); ms.Close(); cs.Close(); // build the token byte[] tokenBytes = new byte[iv.Length + ciphertext.Length]; iv.CopyTo(tokenBytes, 0); ciphertext.CopyTo(tokenBytes, iv.Length); string token = Convert.ToBase64String(tokenBytes); Console.WriteLine(token); return 0; } } Please help. Thank You.

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  • processing an audio wav file with C

    - by sa125
    Hi - I'm working on processing the amplitude of a wav file and scaling it by some decimal factor. I'm trying to wrap my head around how to read and re-write the file in a memory-efficient way while also trying to tackle the nuances of the language (I'm new to C). The file can be in either an 8- or 16-bit format. The way I thought of doing this is by first reading the header data into some pre-defined struct, and then processing the actual data in a loop where I'll read a chunk of data into a buffer, do whatever is needed to it, and then write it to the output. #include <stdio.h> #include <stdlib.h> typedef struct header { char chunk_id[4]; int chunk_size; char format[4]; char subchunk1_id[4]; int subchunk1_size; short int audio_format; short int num_channels; int sample_rate; int byte_rate; short int block_align; short int bits_per_sample; short int extra_param_size; char subchunk2_id[4]; int subchunk2_size; } header; typedef struct header* header_p; void scale_wav_file(char * input, float factor, int is_8bit) { FILE * infile = fopen(input, "rb"); FILE * outfile = fopen("outfile.wav", "wb"); int BUFSIZE = 4000, i, MAX_8BIT_AMP = 255, MAX_16BIT_AMP = 32678; // used for processing 8-bit file unsigned char inbuff8[BUFSIZE], outbuff8[BUFSIZE]; // used for processing 16-bit file short int inbuff16[BUFSIZE], outbuff16[BUFSIZE]; // header_p points to a header struct that contains the file's metadata fields header_p meta = (header_p)malloc(sizeof(header)); if (infile) { // read and write header data fread(meta, 1, sizeof(header), infile); fwrite(meta, 1, sizeof(meta), outfile); while (!feof(infile)) { if (is_8bit) { fread(inbuff8, 1, BUFSIZE, infile); } else { fread(inbuff16, 1, BUFSIZE, infile); } // scale amplitude for 8/16 bits for (i=0; i < BUFSIZE; ++i) { if (is_8bit) { outbuff8[i] = factor * inbuff8[i]; if ((int)outbuff8[i] > MAX_8BIT_AMP) { outbuff8[i] = MAX_8BIT_AMP; } } else { outbuff16[i] = factor * inbuff16[i]; if ((int)outbuff16[i] > MAX_16BIT_AMP) { outbuff16[i] = MAX_16BIT_AMP; } else if ((int)outbuff16[i] < -MAX_16BIT_AMP) { outbuff16[i] = -MAX_16BIT_AMP; } } } // write to output file for 8/16 bit if (is_8bit) { fwrite(outbuff8, 1, BUFSIZE, outfile); } else { fwrite(outbuff16, 1, BUFSIZE, outfile); } } } // cleanup if (infile) { fclose(infile); } if (outfile) { fclose(outfile); } if (meta) { free(meta); } } int main (int argc, char const *argv[]) { char infile[] = "file.wav"; float factor = 0.5; scale_wav_file(infile, factor, 0); return 0; } I'm getting differing file sizes at the end (by 1k or so, for a 40Mb file), and I suspect this is due to the fact that I'm writing an entire buffer to the output, even though the file may have terminated before filling the entire buffer size. Also, the output file is messed up - won't play or open - so I'm probably doing the whole thing wrong. Any tips on where I'm messing up will be great. Thanks!

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  • Using GA in GUI

    - by AlexT
    Sorry if this isn't clear as I'm writing this on a mobile device and I'm trying to make it quick. I've written a basic Genetic Algorithm with a binary encoding (genes) that builds a fitness value and evolves through several iterations using tournament selection, mutation and crossover. As a basic command-line example it seems to work. The problem I've got is with applying a genetic algorithm within a GUI as I am writing a maze-solving program that uses the GA to find a method through a maze. How do I turn my random binary encoded genes and fitness function (add all the binary values together) into a method to control a bot around a maze? I have built a basic GUI in Java consisting of a maze of labels (like a grid) with the available routes being in blue and the walls being in black. To reiterate my GA performs well and contains what any typical GA would (fitness method, get and set population, selection, crossover, etc) but now I need to plug it into a GUI to get my maze running. What needs to go where in order to get a bot that can move in different directions depending on what the GA says? Rough pseudocode would be great if possible As requested, an Individual is built using a separate class (Indiv), with all the main work being done in a Pop class. When a new individual is instantiated an array of ints represent the genes of said individual, with the genes being picked at random from a number between 0 and 1. The fitness function merely adds together the value of these genes and in the Pop class handles selection, mutation and crossover of two selected individuals. There's not much else to it, the command line program just shows evolution over n generations with the total fitness improving over each iteration. EDIT: It's starting to make a bit more sense now, although there are a few things that are bugging me... As Adamski has suggested I want to create an "Agent" with the options shown below. The problem I have is where the random bit string comes into play here. The agent knows where the walls are and has it laid out in a 4 bit string (i.e. 0111), but how does this affect the random 32 bit string? (i.e. 10001011011001001010011011010101) If I have the following maze (x is the start place, 2 is the goal, 1 is the wall): x 1 1 1 1 0 0 1 0 0 1 0 0 0 2 If I turn left I'm facing the wrong way and the agent will move completely off the maze if it moves forward. I assume that the first generation of the string will be completely random and it will evolve as the fitness grows but I don't get how the string will work within a maze. So, to get this straight... The fitness is the result of when the agent is able to move and is by a wall. The genes are a string of 32 bits, split into 16 sets of 2 bits to show the available actions and for the robot to move the two bits need to be passed with four bits from the agent showings its position near the walls. If the move is to go past a wall the move isn't made and it is deemed invalid and if the move is made and if a new wall is found then the fitness goes up. Is that right?

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  • Problems re-populating select options in Rails when form returned with errors

    - by Rick
    I have a form with 2 select options in it -- frequency and duration. When there are errors with the form, and it is returned to the browser, the select options are not re-populated with the selections the user made even though the returned values for those fields match the values of options in the selects. Also, when the form is returned, these fields are not marked as having errors even though their values are blank. Here's the frequency and duration fields in Rails <%= frequency_select c, :frequency %> <%= duration_select c, :duration %> The method for frequency_select is def frequency_select(f, method) options = [["day", 1.day], ["other day", 2.days], ["week", 1.week]] f.select method, options, :include_blank => true end And the method for duration_select is def duration_select(f, method, unit="day" ) values, units = *case unit when "day" : [[[5, 5], [15, 15], [30, 29]], "days"] when "other day" : [[[15, 15], [30, 29], [45,45]], "days"] when "week" : [[[4, 29], [6, 43], [8, 57]], "weeks"] end f.select method, values.map {|(label, i)| ["#{label} #{units}", i.days]}, :include_blank => true end If you enter a value into one or both of these fields and submit the form without completing part of it (any part of it), the form is returned to the user (as would be expected), but the duration and frequency fields are not re-populated with the user's selection. If I add this bit of code to the form <p><%= @challenge.attributes.inspect %></p> I see that this for duration and frequency when the form is returned to the browser: "duration"=>3888000, "frequency"=>172800 These values match values on the options in the select fields. Is there anything special in Rails that needs to be done so that the select fields are re-populated with the user's selections? Any thoughts on what the problem could be or what I should try next? Help is greatly appreciated! -Rick PS If you look at some of the other questions, you'll notice I've asked about this in the past. At one point, I thought the form was returning values for frequency and duration in days rather than seconds, but that's not the case. PPS Here's one other bit of information that might matter, but my tests indicate that it probably does not. (Though, I'm a bit of a newbie to this, so don't take my word for it.) These two fields are chained together using the cascade jquery plugin. The javascript is included on the page (not in a separate file) and some of the js is being created by Rails. First, here are the scripts as they appear in the browser. The first is the script to generate the options for the duration select and the second is the script required by the Cascade plugin to trigger the field chaining. <script type="text/javascript"> var list1 = [ {'When':'86400','Value':' ','Text':' '}, {'When':'172800','Value':' ','Text':' '}, {'When':'604800','Value':' ','Text':' '}, {'When':'86400','Value':'432000','Text':'5 days'}, {'When':'86400','Value':'1296000','Text':'15 days'}, {'When':'86400','Value':'2505600','Text':'30 days'}, {'When':'172800','Value':'1296000','Text':'15 days'}, {'When':'172800','Value':'2505600','Text':'30 days'}, {'When':'172800','Value':'3888000','Text':'45 days'}, {'When':'604800','Value':'2505600','Text':'4 weeks'}, {'When':'604800','Value':'3715200','Text':'6 weeks'}, {'When':'604800','Value':'4924800','Text':'8 weeks'} ]; function commonTemplate(item) { return "<option value='" + item.Value + "'>" + item.Text + "</option>"; }; function commonMatch(selectedValue) { return this.When == selectedValue; }; </script> <script type="text/javascript"> jQuery(document).ready(function(){ jQuery("#challenge_duration, #user_challenge_duration").cascade("#challenge_frequency, #user_challenge_frequency",{ list: list1, template: commonTemplate, match: commonMatch }) }); </script> And here's a bit of the the first script as it is in the erb file -- you see that some of the script is being generated by Rails <%= [ [1.day, [[5, 5], [15,15], [30, 29]], "days"], [2.days, [[15, 15], [30, 29], [45, 45]], "days"], [1.week, [[4, 29], [6, 43], [8, 57]], "weeks"]].map do |(frequency, durations, unit)| durations.map do |(label, value)| "{'When':'#{frequency}','Value':'#{value.days}','Text':'#{label} #{unit}'}" end end.join(",\n") -%> Now, the reason I don't think that it matters whether the duration is being generated with JS is the problem still exists if I remove all the JS the problem also affects the frequency field, whose options are not being generated by the JS

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  • Large Object Heap Fragmentation

    - by Paul Ruane
    The C#/.NET application I am working on is suffering from a slow memory leak. I have used CDB with SOS to try to determine what is happening but the data does not seem to make any sense so I was hoping one of you may have experienced this before. The application is running on the 64 bit framework. It is continuously calculating and serialising data to a remote host and is hitting the Large Object Heap (LOH) a fair bit. However, most of the LOH objects I expect to be transient: once the calculation is complete and has been sent to the remote host, the memory should be freed. What I am seeing, however, is a large number of (live) object arrays interleaved with free blocks of memory, e.g., taking a random segment from the LOH: 0:000> !DumpHeap 000000005b5b1000 000000006351da10 Address MT Size ... 000000005d4f92e0 0000064280c7c970 16147872 000000005e45f880 00000000001661d0 1901752 Free 000000005e62fd38 00000642788d8ba8 1056 <-- 000000005e630158 00000000001661d0 5988848 Free 000000005ebe6348 00000642788d8ba8 1056 000000005ebe6768 00000000001661d0 6481336 Free 000000005f214d20 00000642788d8ba8 1056 000000005f215140 00000000001661d0 7346016 Free 000000005f9168a0 00000642788d8ba8 1056 000000005f916cc0 00000000001661d0 7611648 Free 00000000600591c0 00000642788d8ba8 1056 00000000600595e0 00000000001661d0 264808 Free ... Obviously I would expect this to be the case if my application were creating long-lived, large objects during each calculation. (It does do this and I accept there will be a degree of LOH fragmentation but that is not the problem here.) The problem is the very small (1056 byte) object arrays you can see in the above dump which I cannot see in code being created and which are remaining rooted somehow. Also note that CDB is not reporting the type when the heap segment is dumped: I am not sure if this is related or not. If I dump the marked (<--) object, CDB/SOS reports it fine: 0:015> !DumpObj 000000005e62fd38 Name: System.Object[] MethodTable: 00000642788d8ba8 EEClass: 00000642789d7660 Size: 1056(0x420) bytes Array: Rank 1, Number of elements 128, Type CLASS Element Type: System.Object Fields: None The elements of the object array are all strings and the strings are recognisable as from our application code. Also, I am unable to find their GC roots as the !GCRoot command hangs and never comes back (I have even tried leaving it overnight). So, I would very much appreciate it if anyone could shed any light as to why these small (<85k) object arrays are ending up on the LOH: what situations will .NET put a small object array in there? Also, does anyone happen to know of an alternative way of ascertaining the roots of these objects? Thanks in advance. Update 1 Another theory I came up with late yesterday is that these object arrays started out large but have been shrunk leaving the blocks of free memory that are evident in the memory dumps. What makes me suspicious is that the object arrays always appear to be 1056 bytes long (128 elements), 128 * 8 for the references and 32 bytes of overhead. The idea is that perhaps some unsafe code in a library or in the CLR is corrupting the number of elements field in the array header. Bit of a long shot I know... Update 2 Thanks to Brian Rasmussen (see accepted answer) the problem has been identified as fragmentation of the LOH caused by the string intern table! I wrote a quick test application to confirm this: static void Main() { const int ITERATIONS = 100000; for (int index = 0; index < ITERATIONS; ++index) { string str = "NonInterned" + index; Console.Out.WriteLine(str); } Console.Out.WriteLine("Continue."); Console.In.ReadLine(); for (int index = 0; index < ITERATIONS; ++index) { string str = string.Intern("Interned" + index); Console.Out.WriteLine(str); } Console.Out.WriteLine("Continue?"); Console.In.ReadLine(); } The application first creates and dereferences unique strings in a loop. This is just to prove that the memory does not leak in this scenario. Obviously it should not and it does not. In the second loop, unique strings are created and interned. This action roots them in the intern table. What I did not realise is how the intern table is represented. It appears it consists of a set of pages -- object arrays of 128 string elements -- that are created in the LOH. This is more evident in CDB/SOS: 0:000> .loadby sos mscorwks 0:000> !EEHeap -gc Number of GC Heaps: 1 generation 0 starts at 0x00f7a9b0 generation 1 starts at 0x00e79c3c generation 2 starts at 0x00b21000 ephemeral segment allocation context: none segment begin allocated size 00b20000 00b21000 010029bc 0x004e19bc(5118396) Large object heap starts at 0x01b21000 segment begin allocated size 01b20000 01b21000 01b8ade0 0x00069de0(433632) Total Size 0x54b79c(5552028) ------------------------------ GC Heap Size 0x54b79c(5552028) Taking a dump of the LOH segment reveals the pattern I saw in the leaking application: 0:000> !DumpHeap 01b21000 01b8ade0 ... 01b8a120 793040bc 528 01b8a330 00175e88 16 Free 01b8a340 793040bc 528 01b8a550 00175e88 16 Free 01b8a560 793040bc 528 01b8a770 00175e88 16 Free 01b8a780 793040bc 528 01b8a990 00175e88 16 Free 01b8a9a0 793040bc 528 01b8abb0 00175e88 16 Free 01b8abc0 793040bc 528 01b8add0 00175e88 16 Free total 1568 objects Statistics: MT Count TotalSize Class Name 00175e88 784 12544 Free 793040bc 784 421088 System.Object[] Total 1568 objects Note that the object array size is 528 (rather than 1056) because my workstation is 32 bit and the application server is 64 bit. The object arrays are still 128 elements long. So the moral to this story is to be very careful interning. If the string you are interning is not known to be a member of a finite set then your application will leak due to fragmentation of the LOH, at least in version 2 of the CLR. In our application's case, there is general code in the deserialisation code path that interns entity identifiers during unmarshalling: I now strongly suspect this is the culprit. However, the developer's intentions were obviously good as they wanted to make sure that if the same entity is deserialised multiple times then only one instance of the identifier string will be maintained in memory.

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  • How to Play FLAC Files in Windows 7 Media Center & Player

    - by Mysticgeek
    An annoyance for music lovers who enjoy FLAC format, is there’s no native support for WMP or WMC. If you’re a music enthusiast who prefers FLAC format, we’ll look at adding support to Windows 7 Media Center and Player. For the following article we are using Windows 7 Home Premium 32-bit edition. Download and Install madFLAC v1.8 The first thing we need to do is download and install the madFLAC v1.8 decoder (link below). Just unzip the file and run install.bat… You’ll get a message that it has been successfully registered, click Ok. To verify everything is working, open up one of your FLAC files with WMP, and you’ll get the following message. Check the box Don’t ask me again for this extension and click Yes. Now Media Player should play the track you’ve chosen.   Delete Current Music Library But what if you want to add your entire collection of FLAC files to the Library? If you already have it set up as your default music player, unfortunately we need to remove the current library and delete the database. The best way to manage the music library in Windows 7 is via WMP 12. Since we don’t want to delete songs from the computer we need to Open WMP, press “Alt+T” and navigate to Tools \ Options \ Library.   Now uncheck the box Delete files from computer when deleted from library and click Ok. Now in your Library click “Ctrl + A” to highlight all of the songs in the Library, then hit the “Delete” key. If you have a lot of songs in your library (like on our system) you’ll see the following dialog box while it collects all of the information.   After all of the data is collected, make sure the radio button next to Delete from library only is marked and click Ok. Again you’ll see the Working progress window while the songs are deleted. Deleting Current Database Now we need to make sure we’re starting out fresh. Close out of Media Player, then we’ll basically follow the same directions The Geek pointed out for fixing the WMP Library. Click on Start and type in services.msc into the search box and hit Enter. Now scroll down and stop the service named Windows Media Player Network Sharing Service. Now, navigate to the following directory and the main file to delete CurrentDatabase_372.wmdb %USERPROFILE%\Local Settings\Application Data\Microsoft\Media Player\ Again, the main file to delete is CurrentDatabase_372.wmdb, though if you want, you can delete them all. If you’re uneasy about deleting these files, make sure to back them up first. Now after you restart WMP you can begin adding your FLAC files. For those of us with large collections, it’s extremely annoying to see WMP try to pick up all of your media by default. To delete the other directories go to Organize \ Manage Libraries then open the directories you want to remove. For example here we’re removing the default libraries it tries to check for music. Remove the directories you don’t want it to gather contents from in each of the categories. We removed all of the other collections and only added the FLAC music directory from our home server. SoftPointer Tag Support Plugin Even though we were able to get FLAC files to play in WMP and WMC at this point, there’s another utility from SoftPointer to add. It enables FLAC (and other file formats) to be picked up in the library much easier. It has a long name but is effective –M4a/FLAC/Ogg/Ape/Mpc Tag Support Plugin for Media Player and Media Center (link below). Just install it by accepting the defaults, and you’ll be glad you did. After installing it, and re-launching Media Player, give it some time to collect all of the data from your FLAC directory…it can take a while. In fact, if your collection is huge, just walk away and let it do its thing. If you try to use it right away, WMP slows down considerably while updating the library.   Once the library is setup you’ll be able to play your FLAC tunes in Windows 7 Media Center as well and Windows Media Player 12.   Album Art One caveat is that some of our albums didn’t show any cover art. But we were usually able to get it by right-clicking the album and selecting Find album info.   Then confirming the album information is correct…   Conclusion Although this seems like several steps to go through to play FLAC files in Windows 7 Media Center and Player, it seems to work really well after it’s set up. We haven’t tried this with a 64-bit machine, but the process should be similar, but you might want to make sure the codecs you use are 64-bit. We’re sure there are other methods out there that some of you use, and if so leave us a comment and tell us about it. Download madFlac V1.8  M4a/FLAC/Ogg/Ape/Mpc Tag Support Plugin for Media Player and Media Center from SoftPointer Similar Articles Productive Geek Tips How to Play .OGM Video Files in Windows VistaFixing When Windows Media Player Library Won’t Let You Add FilesUsing Netflix Watchnow in Windows Vista Media Center (Gmedia)Kantaris is a Unique Media Player Based on VLCEasily Change Audio File Formats with XRECODE TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional OutSync will Sync Photos of your Friends on Facebook and Outlook Windows 7 Easter Theme YoWindoW, a real time weather screensaver Optimize your computer the Microsoft way Stormpulse provides slick, real time weather data Geek Parents – Did you try Parental Controls in Windows 7?

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  • Create Chemistry Equations and Diagrams in Word

    - by Matthew Guay
    Microsoft Word is a great tool for formatting text, but what if you want to insert a chemistry formula or diagram?  Thanks to a new free add-in for Word, you can now insert high-quality chemistry formulas and diagrams directly from the Ribbon in Word. Microsoft’s new Education Labs has recently released the new Chemistry Add-in for Word 2007 and 2010.  This free download adds support for entering and editing chemistry symbols, diagrams, and formulas using the standard XML based Chemical Markup Language.  You can convert any chemical name, such as benzene, or formula, such as H2O, into a chemical diagram, standard name, or formula.  Whether you’re a professional chemist, just taking chemistry in school, or simply curious about the makeup of Citric Acid, this add-in is an exciting way to bring chemistry to your computer. This add-in works great on Word 2007 and 2010, including the 64 bit version of Word 2010.  Please note that the current version is still in beta, so only run it if you are comfortable running beta products. Getting Started Download the Chemistry add-in from Microsoft Education Labs (link below), and unzip the file.  Then, run the ChemistryAddinforWordBeta2.Setup.msi. It may inform you that you need to install the Visual Studio Tools for Office 3.0.  Simply click Yes to download these tools. This will open the download in your default browser.  Simply click run, or save and then run it when it is downloaded. Now, click next to install the Visual Studio Tools for Office as usual. When this is finished, run the ChemistryAddinforWordBeta2.Setup.msi again.  This time, you can easily install it with the default options. Once it’s finished installing, open Word to try out the Chemistry Add-in.  You will be asked if you want to install this customization, so click Install to enable it. Now you will have a new Chemistry tab in your Word ribbon.  Here’s the ribbon in Word 2010… And here it is in Word 2007.   Using the Chemistry Add-in It’s very easy to insert nice chemistry diagrams and formulas in Word with the Chemistry add-in.  You can quickly insert a premade diagram from the Chemistry Gallery: Or you can insert a formula from file.  Simply click “From File” and choose any Chemical Markup Language (.cml) formatted file to insert the chemical formula. You can also convert any chemical name to it’s chemical form.  Simply select the word, right-click, select “Convert to Chemistry Zone” and then click on its name. Now you can see the chemical form in the sidebar if you click the Chemistry Navigator button, and can choose to insert the diagram into the document.  Some chemicals will automatically convert to the diagram in the document, while others simply link to it in the sidebar.  Either way, you can display exactly what you want. You can also convert a chemical formula directly to it’s chemical diagram.  Here we entered H2O and converted it to Chemistry Zone: This directly converted it to the diagram directly in the document. You can click the Edit button on the top, and from there choose to either edit the 2D model of the chemical, or edit the labels. When you click Edit Labels, you may be asked which form you wish to display.  Here’s the options for potassium permanganate: You can then edit the names and formulas, and add or remove any you wish. If you choose to edit the chemical in 2D, you can even edit the individual atoms and change the chemical you’re diagramming.  This 2D editor has a lot of options, so you can get your chemical diagram to look just like you want. And, if you need any help or want to learn more about the Chemistry add-in and its features, simply click the help button in the Chemistry Ribbon.  This will open a Word document containing examples and explanations which can be helpful in mastering all the features of this add-in. All of this works perfectly, whether you’re running it in Word 2007 or 2010, 32 or 64 bit editions. Conclusion Whether you’re using chemistry formulas everyday or simply want to investigate a chemical makeup occasionally, this is a great way to do it with tools you already have on your computer.  It will also help make homework a bit easier if you’re struggling with it in high school or college. Links Download the Chemistry Add-in for Word Introducing Chemistry Add-in for Word – MSDN blogs Chemistry Markup Language – Wikipedia Similar Articles Productive Geek Tips Geek Reviews: Using Dia as a Free Replacement for Microsoft VisioEasily Summarize A Word 2007 DocumentCreate a Hyperlink in a Word 2007 Flow Chart and Hide Annoying ScreenTipsHow To Create and Publish Blog Posts in Word 2010 & 2007Using Word 2007 as a Blogging Tool TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Windows 7 Easter Theme YoWindoW, a real time weather screensaver Optimize your computer the Microsoft way Stormpulse provides slick, real time weather data Geek Parents – Did you try Parental Controls in Windows 7? Change DNS servers on the fly with DNS Jumper

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  • Windows Phone 7 development: first impressions

    - by DigiMortal
    After hard week in work I got some free time to play with Windows Phone 7 CTP developer tools. Although my first test application is still unfinished I think it is good moment to share my first experiences to you. In this posting I will give you quick overview of Windows Phone 7 developer tools from developer perspective. If you are familiar with Visual Studio 2010 then you will feel comfortable because Windows Phone 7 CTP developer tools base on Visual Studio 2010 Express. Project templates There are five project templates available. Three of them are based on Silverlight and two on XNA Game Studio: Windows Phone Application (Silverlight) Windows Phone List Application (Silverlight) Windows Phone Class Library (Silverlight) Windows Phone Game (XNA Game Studio) Windows Phone Game Library (XNA Game Studio) Currently I am writing to test applications. One of them is based on Windows Phone Application and the other on Windows Phone List Application project template. After creating these projects you see the following views in Visual Studio. Windows Phone Application. Click on image to enlarge. Windows Phone List Application. Click on image to enlarge.  I suggest you to use some of these templates to get started more easily. Windows Phone 7 emulator You can run your Windows Phone 7 applications on Windows Phone 7 emulator that comes with developer tools CTP. If you run your application then emulator is started automatically and you can try out how your application works in phone-like emulator. You can see screenshot of emulator on right. Currently there is opened Windows Phone List Application as it is created by default. Click on image to enlarge it. Emulator is a little bit slow and uncomfortable but it works pretty well. This far I have caused only couple of crashes during my experiments. In these cases emulator works but Visual Studio gets stuck because it cannot communicate with emulator. One important note. Emulator is based on virtual machine although you can see only phone screen and options toolbar. If you want to run emulator you must close all virtual machines running on your machine and run Visual Studio 2010 as administrator. Once you run emulator you can keep it open because you can stop your application in Visual Studio, modify, compile and re-deploy it without restarting emulator. Designing user interfaces You can design user interface of your application in Visual Studio. When you open XAML-files it is displayed in window with two panels. Left panel shows you device screen and works as visual design environment while right panel shows you XAML mark-up and let’s you modify XML if you need it. As it is one of my very first Silverlight applications I felt more comfortable with XAML editor because property names in property boxes of visual designer confused me a little bit. Designer panel is not very good because it is visually hard to follow. It has black background that makes dark borders of controls very hard to see. If you have monitor with very high contrast then it is may be not a real problem. I have usual monitor and I have problem. :) Putting controls on design surface, dragging and resizing them is also pretty painful. Some controls are drawn correctly but for some controls you have to set width and height in XML so they can be resized. After some practicing it is not so annoying anymore. On the right you can see toolbox with some controllers. This is all you get out of the box. But it is sufficient to get started. After getting some experiences you can create your own controls or use existing ones from other vendors or developers. If it is your first time to do stuff with Silverlight then keep Google open – you need it hard. After getting over the first shock you get the point very quickly and start developing at normal speed. :) Writing source code Writing source code is the most familiar part of this action. Good old Visual Studio code editor with all nice features it has. But here you get also some surprises: The anatomy of Silverlight controls is a little bit different than the one of user controls in web and forms projects. Windows Phone 7 doesn’t run on full version of Windows (I bet it is some version of Windows CE or something like this) then there is less system classes you can use. Some familiar classes have less methods that in full version of .NET Framework and in these cases you have to write all the code by yourself or find libraries or source code from somewhere. These problems are really not so much problems than limitations and you get easily over them. Conclusion Windows Phone 7 CTP developer tools help you do a lot of things on Windows Phone 7. Although I expected better performance from tools I think that current performance is not a problem. This far my first test project is going very well and Google has answer for almost every question. Windows Phone 7 is mobile device and therefore it has less hardware resources than desktop computers. This is why toolset is so limited. The more you need memory the more slower is device and as you may guess it needs the more battery. If you are writing apps for mobile devices then make your best to get your application use as few resources as possible and act as fast as possible.

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  • Using HTML 5 SessionState to save rendered Page Content

    - by Rick Strahl
    HTML 5 SessionState and LocalStorage are very useful and super easy to use to manage client side state. For building rich client side or SPA style applications it's a vital feature to be able to cache user data as well as HTML content in order to swap pages in and out of the browser's DOM. What might not be so obvious is that you can also use the sessionState and localStorage objects even in classic server rendered HTML applications to provide caching features between pages. These APIs have been around for a long time and are supported by most relatively modern browsers and even all the way back to IE8, so you can use them safely in your Web applications. SessionState and LocalStorage are easy The APIs that make up sessionState and localStorage are very simple. Both object feature the same API interface which  is a simple, string based key value store that has getItem, setItem, removeitem, clear and  key methods. The objects are also pseudo array objects and so can be iterated like an array with  a length property and you have array indexers to set and get values with. Basic usage  for storing and retrieval looks like this (using sessionStorage, but the syntax is the same for localStorage - just switch the objects):// set var lastAccess = new Date().getTime(); if (sessionStorage) sessionStorage.setItem("myapp_time", lastAccess.toString()); // retrieve in another page or on a refresh var time = null; if (sessionStorage) time = sessionStorage.getItem("myapp_time"); if (time) time = new Date(time * 1); else time = new Date(); sessionState stores data that is browser session specific and that has a liftetime of the active browser session or window. Shut down the browser or tab and the storage goes away. localStorage uses the same API interface, but the lifetime of the data is permanently stored in the browsers storage area until deleted via code or by clearing out browser cookies (not the cache). Both sessionStorage and localStorage space is limited. The spec is ambiguous about this - supposedly sessionStorage should allow for unlimited size, but it appears that most WebKit browsers support only 2.5mb for either object. This means you have to be careful what you store especially since other applications might be running on the same domain and also use the storage mechanisms. That said 2.5mb worth of character data is quite a bit and would go a long way. The easiest way to get a feel for how sessionState and localStorage work is to look at a simple example. You can go check out the following example online in Plunker: http://plnkr.co/edit/0ICotzkoPjHaWa70GlRZ?p=preview which looks like this: Plunker is an online HTML/JavaScript editor that lets you write and run Javascript code and similar to JsFiddle, but a bit cleaner to work in IMHO (thanks to John Papa for turning me on to it). The sample has two text boxes with counts that update session/local storage every time you click the related button. The counts are 'cached' in Session and Local storage. The point of these examples is that both counters survive full page reloads, and the LocalStorage counter survives a complete browser shutdown and restart. Go ahead and try it out by clicking the Reload button after updating both counters and then shutting down the browser completely and going back to the same URL (with the same browser). What you should see is that reloads leave both counters intact at the counted values, while a browser restart will leave only the local storage counter intact. The code to deal with the SessionStorage (and LocalStorage not shown here) in the example is isolated into a couple of wrapper methods to simplify the code: function getSessionCount() { var count = 0; if (sessionStorage) { var count = sessionStorage.getItem("ss_count"); count = !count ? 0 : count * 1; } $("#txtSession").val(count); return count; } function setSessionCount(count) { if (sessionStorage) sessionStorage.setItem("ss_count", count.toString()); } These two functions essentially load and store a session counter value. The two key methods used here are: sessionStorage.getItem(key); sessionStorage.setItem(key,stringVal); Note that the value given to setItem and return by getItem has to be a string. If you pass another type you get an error. Don't let that limit you though - you can easily enough store JSON data in a variable so it's quite possible to pass complex objects and store them into a single sessionStorage value:var user = { name: "Rick", id="ricks", level=8 } sessionStorage.setItem("app_user",JSON.stringify(user)); to retrieve it:var user = sessionStorage.getItem("app_user"); if (user) user = JSON.parse(user); Simple! If you're using the Chrome Developer Tools (F12) you can also check out the session and local storage state on the Resource tab:   You can also use this tool to refresh or remove entries from storage. What we just looked at is a purely client side implementation where a couple of counters are stored. For rich client centric AJAX applications sessionStorage and localStorage provide a very nice and simple API to store application state while the application is running. But you can also use these storage mechanisms to manage server centric HTML applications when you combine server rendering with some JavaScript to perform client side data caching. You can both store some state information and data on the client (ie. store a JSON object and carry it forth between server rendered HTML requests) or you can use it for good old HTTP based caching where some rendered HTML is saved and then restored later. Let's look at the latter with a real life example. Why do I need Client-side Page Caching for Server Rendered HTML? I don't know about you, but in a lot of my existing server driven applications I have lists that display a fair amount of data. Typically these lists contain links to then drill down into more specific data either for viewing or editing. You can then click on a link and go off to a detail page that provides more concise content. So far so good. But now you're done with the detail page and need to get back to the list, so you click on a 'bread crumbs trail' or an application level 'back to list' button and… …you end up back at the top of the list - the scroll position, the current selection in some cases even filters conditions - all gone with the wind. You've left behind the state of the list and are starting from scratch in your browsing of the list from the top. Not cool! Sound familiar? This a pretty common scenario with server rendered HTML content where it's so common to display lists to drill into, only to lose state in the process of returning back to the original list. Look at just about any traditional forums application, or even StackOverFlow to see what I mean here. Scroll down a bit to look at a post or entry, drill in then use the bread crumbs or tab to go back… In some cases returning to the top of a list is not a big deal. On StackOverFlow that sort of works because content is turning around so quickly you probably want to actually look at the top posts. Not always though - if you're browsing through a list of search topics you're interested in and drill in there's no way back to that position. Essentially anytime you're actively browsing the items in the list, that's when state becomes important and if it's not handled the user experience can be really disrupting. Content Caching If you're building client centric SPA style applications this is a fairly easy to solve problem - you tend to render the list once and then update the page content to overlay the detail content, only hiding the list temporarily until it's used again later. It's relatively easy to accomplish this simply by hiding content on the page and later making it visible again. But if you use server rendered content, hanging on to all the detail like filters, selections and scroll position is not quite as easy. Or is it??? This is where sessionStorage comes in handy. What if we just save the rendered content of a previous page, and then restore it when we return to this page based on a special flag that tells us to use the cached version? Let's see how we can do this. A real World Use Case Recently my local ISP asked me to help out with updating an ancient classifieds application. They had a very busy, local classifieds app that was originally an ASP classic application. The old app was - wait for it: frames based - and even though I lobbied against it, the decision was made to keep the frames based layout to allow rapid browsing of the hundreds of posts that are made on a daily basis. The primary reason they wanted this was precisely for the ability to quickly browse content item by item. While I personally hate working with Frames, I have to admit that the UI actually works well with the frames layout as long as you're running on a large desktop screen. You can check out the frames based desktop site here: http://classifieds.gorge.net/ However when I rebuilt the app I also added a secondary view that doesn't use frames. The main reason for this of course was for mobile displays which work horribly with frames. So there's a somewhat mobile friendly interface to the interface, which ditches the frames and uses some responsive design tweaking for mobile capable operation: http://classifeds.gorge.net/mobile  (or browse the base url with your browser width under 800px)   Here's what the mobile, non-frames view looks like:   As you can see this means that the list of classifieds posts now is a list and there's a separate page for drilling down into the item. And of course… originally we ran into that usability issue I mentioned earlier where the browse, view detail, go back to the list cycle resulted in lost list state. Originally in mobile mode you scrolled through the list, found an item to look at and drilled in to display the item detail. Then you clicked back to the list and BAM - you've lost your place. Because there are so many items added on a daily basis the full list is never fully loaded, but rather there's a "Load Additional Listings"  entry at the button. Not only did we originally lose our place when coming back to the list, but any 'additionally loaded' items are no longer there because the list was now rendering  as if it was the first page hit. The additional listings, and any filters, the selection of an item all were lost. Major Suckage! Using Client SessionStorage to cache Server Rendered Content To work around this problem I decided to cache the rendered page content from the list in SessionStorage. Anytime the list renders or is updated with Load Additional Listings, the page HTML is cached and stored in Session Storage. Any back links from the detail page or the login or write entry forms then point back to the list page with a back=true query string parameter. If the server side sees this parameter it doesn't render the part of the page that is cached. Instead the client side code retrieves the data from the sessionState cache and simply inserts it into the page. It sounds pretty simple, and the overall the process is really easy, but there are a few gotchas that I'll discuss in a minute. But first let's look at the implementation. Let's start with the server side here because that'll give a quick idea of the doc structure. As I mentioned the server renders data from an ASP.NET MVC view. On the list page when returning to the list page from the display page (or a host of other pages) looks like this: https://classifieds.gorge.net/list?back=True The query string value is a flag, that indicates whether the server should render the HTML. Here's what the top level MVC Razor view for the list page looks like:@model MessageListViewModel @{ ViewBag.Title = "Classified Listing"; bool isBack = !string.IsNullOrEmpty(Request.QueryString["back"]); } <form method="post" action="@Url.Action("list")"> <div id="SizingContainer"> @if (!isBack) { @Html.Partial("List_CommandBar_Partial", Model) <div id="PostItemContainer" class="scrollbox" xstyle="-webkit-overflow-scrolling: touch;"> @Html.Partial("List_Items_Partial", Model) @if (Model.RequireLoadEntry) { <div class="postitem loadpostitems" style="padding: 15px;"> <div id="LoadProgress" class="smallprogressright"></div> <div class="control-progress"> Load additional listings... </div> </div> } </div> } </div> </form> As you can see the query string triggers a conditional block that if set is simply not rendered. The content inside of #SizingContainer basically holds  the entire page's HTML sans the headers and scripts, but including the filter options and menu at the top. In this case this makes good sense - in other situations the fact that the menu or filter options might be dynamically updated might make you only cache the list rather than essentially the entire page. In this particular instance all of the content works and produces the proper result as both the list along with any filter conditions in the form inputs are restored. Ok, let's move on to the client. On the client there are two page level functions that deal with saving and restoring state. Like the counter example I showed earlier, I like to wrap the logic to save and restore values from sessionState into a separate function because they are almost always used in several places.page.saveData = function(id) { if (!sessionStorage) return; var data = { id: id, scroll: $("#PostItemContainer").scrollTop(), html: $("#SizingContainer").html() }; sessionStorage.setItem("list_html",JSON.stringify(data)); }; page.restoreData = function() { if (!sessionStorage) return; var data = sessionStorage.getItem("list_html"); if (!data) return null; return JSON.parse(data); }; The data that is saved is an object which contains an ID which is the selected element when the user clicks and a scroll position. These two values are used to reset the scroll position when the data is used from the cache. Finally the html from the #SizingContainer element is stored, which makes for the bulk of the document's HTML. In this application the HTML captured could be a substantial bit of data. If you recall, I mentioned that the server side code renders a small chunk of data initially and then gets more data if the user reads through the first 50 or so items. The rest of the items retrieved can be rather sizable. Other than the JSON deserialization that's Ok. Since I'm using SessionStorage the storage space has no immediate limits. Next is the core logic to handle saving and restoring the page state. At first though this would seem pretty simple, and in some cases it might be, but as the following code demonstrates there are a few gotchas to watch out for. Here's the relevant code I use to save and restore:$( function() { … var isBack = getUrlEncodedKey("back", location.href); if (isBack) { // remove the back key from URL setUrlEncodedKey("back", "", location.href); var data = page.restoreData(); // restore from sessionState if (!data) { // no data - force redisplay of the server side default list window.location = "list"; return; } $("#SizingContainer").html(data.html); var el = $(".postitem[data-id=" + data.id + "]"); $(".postitem").removeClass("highlight"); el.addClass("highlight"); $("#PostItemContainer").scrollTop(data.scroll); setTimeout(function() { el.removeClass("highlight"); }, 2500); } else if (window.noFrames) page.saveData(null); // save when page loads $("#SizingContainer").on("click", ".postitem", function() { var id = $(this).attr("data-id"); if (!id) return true; if (window.noFrames) page.saveData(id); var contentFrame = window.parent.frames["Content"]; if (contentFrame) contentFrame.location.href = "show/" + id; else window.location.href = "show/" + id; return false; }); … The code starts out by checking for the back query string flag which triggers restoring from the client cache. If cached the cached data structure is read from sessionStorage. It's important here to check if data was returned. If the user had back=true on the querystring but there is no cached data, he likely bookmarked this page or otherwise shut down the browser and came back to this URL. In that case the server didn't render any detail and we have no cached data, so all we can do is redirect to the original default list view using window.location. If we continued the page would render no data - so make sure to always check the cache retrieval result. Always! If there is data the it's loaded and the data.html data is restored back into the document by simply injecting the HTML back into the document's #SizingContainer element:$("#SizingContainer").html(data.html); It's that simple and it's quite quick even with a fully loaded list of additional items and on a phone. The actual HTML data is stored to the cache on every page load initially and then again when the user clicks on an element to navigate to a particular listing. The former ensures that the client cache always has something in it, and the latter updates with additional information for the selected element. For the click handling I use a data-id attribute on the list item (.postitem) in the list and retrieve the id from that. That id is then used to navigate to the actual entry as well as storing that Id value in the saved cached data. The id is used to reset the selection by searching for the data-id value in the restored elements. The overall process of this save/restore process is pretty straight forward and it doesn't require a bunch of code, yet it yields a huge improvement in the usability of the site on mobile devices (or anybody who uses the non-frames view). Some things to watch out for As easy as it conceptually seems to simply store and retrieve cached content, you have to be quite aware what type of content you are caching. The code above is all that's specific to cache/restore cycle and it works, but it took a few tweaks to the rest of the script code and server code to make it all work. There were a few gotchas that weren't immediately obvious. Here are a few things to pay attention to: Event Handling Logic Timing of manipulating DOM events Inline Script Code Bookmarking to the Cache Url when no cache exists Do you have inline script code in your HTML? That script code isn't going to run if you restore from cache and simply assign or it may not run at the time you think it would normally in the DOM rendering cycle. JavaScript Event Hookups The biggest issue I ran into with this approach almost immediately is that originally I had various static event handlers hooked up to various UI elements that are now cached. If you have an event handler like:$("#btnSearch").click( function() {…}); that works fine when the page loads with server rendered HTML, but that code breaks when you now load the HTML from cache. Why? Because the elements you're trying to hook those events to may not actually be there - yet. Luckily there's an easy workaround for this by using deferred events. With jQuery you can use the .on() event handler instead:$("#SelectionContainer").on("click","#btnSearch", function() {…}); which monitors a parent element for the events and checks for the inner selector elements to handle events on. This effectively defers to runtime event binding, so as more items are added to the document bindings still work. For any cached content use deferred events. Timing of manipulating DOM Elements Along the same lines make sure that your DOM manipulation code follows the code that loads the cached content into the page so that you don't manipulate DOM elements that don't exist just yet. Ideally you'll want to check for the condition to restore cached content towards the top of your script code, but that can be tricky if you have components or other logic that might not all run in a straight line. Inline Script Code Here's another small problem I ran into: I use a DateTime Picker widget I built a while back that relies on the jQuery date time picker. I also created a helper function that allows keyboard date navigation into it that uses JavaScript logic. Because MVC's limited 'object model' the only way to embed widget content into the page is through inline script. This code broken when I inserted the cached HTML into the page because the script code was not available when the component actually got injected into the page. As the last bullet - it's a matter of timing. There's no good work around for this - in my case I pulled out the jQuery date picker and relied on native <input type="date" /> logic instead - a better choice these days anyway, especially since this view is meant to be primarily to serve mobile devices which actually support date input through the browser (unlike desktop browsers of which only WebKit seems to support it). Bookmarking Cached Urls When you cache HTML content you have to make a decision whether you cache on the client and also not render that same content on the server. In the Classifieds app I didn't render server side content so if the user comes to the page with back=True and there is no cached content I have to a have a Plan B. Typically this happens when somebody ends up bookmarking the back URL. The easiest and safest solution for this scenario is to ALWAYS check the cache result to make sure it exists and if not have a safe URL to go back to - in this case to the plain uncached list URL which amounts to effectively redirecting. This seems really obvious in hindsight, but it's easy to overlook and not see a problem until much later, when it's not obvious at all why the page is not rendering anything. Don't use <body> to replace Content Since we're practically replacing all the HTML in the page it may seem tempting to simply replace the HTML content of the <body> tag. Don't. The body tag usually contains key things that should stay in the page and be there when it loads. Specifically script tags and elements and possibly other embedded content. It's best to create a top level DOM element specifically as a placeholder container for your cached content and wrap just around the actual content you want to replace. In the app above the #SizingContainer is that container. Other Approaches The approach I've used for this application is kind of specific to the existing server rendered application we're running and so it's just one approach you can take with caching. However for server rendered content caching this is a pattern I've used in a few apps to retrofit some client caching into list displays. In this application I took the path of least resistance to the existing server rendering logic. Here are a few other ways that come to mind: Using Partial HTML Rendering via AJAXInstead of rendering the page initially on the server, the page would load empty and the client would render the UI by retrieving the respective HTML and embedding it into the page from a Partial View. This effectively makes the initial rendering and the cached rendering logic identical and removes the server having to decide whether this request needs to be rendered or not (ie. not checking for a back=true switch). All the logic related to caching is made on the client in this case. Using JSON Data and Client RenderingThe hardcore client option is to do the whole UI SPA style and pull data from the server and then use client rendering or databinding to pull the data down and render using templates or client side databinding with knockout/angular et al. As with the Partial Rendering approach the advantage is that there's no difference in the logic between pulling the data from cache or rendering from scratch other than the initial check for the cache request. Of course if the app is a  full on SPA app, then caching may not be required even - the list could just stay in memory and be hidden and reactivated. I'm sure there are a number of other ways this can be handled as well especially using  AJAX. AJAX rendering might simplify the logic, but it also complicates search engine optimization since there's no content loaded initially. So there are always tradeoffs and it's important to look at all angles before deciding on any sort of caching solution in general. State of the Session SessionState and LocalStorage are easy to use in client code and can be integrated even with server centric applications to provide nice caching features of content and data. In this post I've shown a very specific scenario of storing HTML content for the purpose of remembering list view data and state and making the browsing experience for lists a bit more friendly, especially if there's dynamically loaded content involved. If you haven't played with sessionStorage or localStorage I encourage you to give it a try. There's a lot of cool stuff that you can do with this beyond the specific scenario I've covered here… Resources Overview of localStorage (also applies to sessionStorage) Web Storage Compatibility Modernizr Test Suite© Rick Strahl, West Wind Technologies, 2005-2013Posted in JavaScript  HTML5  ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Alien deletes .deb when converting from .rpm

    - by Stann
    I'm trying to convert .rpm to .deb using alien. sudo alien -k libtetra-1.0.0-2.i386.rpm Alien says that: libtetra-1.0.0-2.i386.deb generated But when I check the folder - there is just original .rpm and no .deb. Also - I can see that for a split second there is a .deb file in a folder. so it looks like alien create .deb and deletes it right away. I suspect that it's maybe because I run 64 bit os and package is 32? Can somebody explain why alien deletes .deb automatically? Verbose output: LANG=C rpm -qp --queryformat %{NAME} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{VERSION} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{RELEASE} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{ARCH} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{CHANGELOGTEXT} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{SUMMARY} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{DESCRIPTION} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{PREFIXES} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{POSTIN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{POSTUN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{PREUN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{LICENSE} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{PREIN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qcp libtetra-1.0.0-2.i386.rpm rpm -qpi libtetra-1.0.0-2.i386.rpm LANG=C rpm -qpl libtetra-1.0.0-2.i386.rpm mkdir libtetra-1.0.0 chmod 755 libtetra-1.0.0 rpm2cpio libtetra-1.0.0-2.i386.rpm | lzma -t -q > /dev/null 2>&1 rpm2cpio libtetra-1.0.0-2.i386.rpm | (cd libtetra-1.0.0; cpio --extract --make-directories --no-absolute-filenames --preserve-modification-time) 2>&1 chmod 755 libtetra-1.0.0/./ chmod 755 libtetra-1.0.0/./usr chmod 755 libtetra-1.0.0/./usr/lib chown 0:0 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 chmod 755 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 mkdir libtetra-1.0.0/debian date -R date -R chmod 755 libtetra-1.0.0/debian/rules debian/rules binary 2>&1 libtetra_1.0.0-3_i386.deb generated find libtetra-1.0.0 -type d -exec chmod 755 {} ; rm -rf libtetra-1.0.0 Very Verbose output LANG=C rpm -qp --queryformat %{NAME} libtetra-1.0.0-2.i386.rpm libtetra LANG=C rpm -qp --queryformat %{VERSION} libtetra-1.0.0-2.i386.rpm 1.0.0 LANG=C rpm -qp --queryformat %{RELEASE} libtetra-1.0.0-2.i386.rpm 2 LANG=C rpm -qp --queryformat %{ARCH} libtetra-1.0.0-2.i386.rpm i386 LANG=C rpm -qp --queryformat %{CHANGELOGTEXT} libtetra-1.0.0-2.i386.rpm - First RPM Package LANG=C rpm -qp --queryformat %{SUMMARY} libtetra-1.0.0-2.i386.rpm Panasonic KX-MC6000 series Printer Driver for Linux. LANG=C rpm -qp --queryformat %{DESCRIPTION} libtetra-1.0.0-2.i386.rpm This software is Panasonic KX-MC6000 series Printer Driver for Linux. You can print from applications by using CUPS(Common Unix Printing System) which is the printing system for Linux. Other functions for KX-MC6000 series are not supported by this software. LANG=C rpm -qp --queryformat %{PREFIXES} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{POSTIN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{POSTUN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{PREUN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{LICENSE} libtetra-1.0.0-2.i386.rpm GPL and LGPL (Version2) LANG=C rpm -qp --queryformat %{PREIN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qcp libtetra-1.0.0-2.i386.rpm rpm -qpi libtetra-1.0.0-2.i386.rpm Name : libtetra Relocations: (not relocatable) Version : 1.0.0 Vendor: Panasonic Communications Co., Ltd. Release : 2 Build Date: Tue 27 Apr 2010 05:16:40 AM EDT Install Date: (not installed) Build Host: localhost.localdomain Group : System Environment/Daemons Source RPM: libtetra-1.0.0-2.src.rpm Size : 31808 License: GPL and LGPL (Version2) Signature : (none) URL : http://panasonic.net/pcc/support/fax/world.htm Summary : Panasonic KX-MC6000 series Printer Driver for Linux. Description : This software is Panasonic KX-MC6000 series Printer Driver for Linux. You can print from applications by using CUPS(Common Unix Printing System) which is the printing system for Linux. Other functions for KX-MC6000 series are not supported by this software. LANG=C rpm -qpl libtetra-1.0.0-2.i386.rpm /usr/lib/libtetra.so /usr/lib/libtetra.so.1.0.0 mkdir libtetra-1.0.0 chmod 755 libtetra-1.0.0 rpm2cpio libtetra-1.0.0-2.i386.rpm | lzma -t -q > /dev/null 2>&1 rpm2cpio libtetra-1.0.0-2.i386.rpm | (cd libtetra-1.0.0; cpio --extract --make-directories --no-absolute-filenames --preserve-modification-time) 2>&1 63 blocks chmod 755 libtetra-1.0.0/./ chmod 755 libtetra-1.0.0/./usr chmod 755 libtetra-1.0.0/./usr/lib chown 0:0 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 chmod 755 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 mkdir libtetra-1.0.0/debian date -R Mon, 07 Feb 2011 11:03:58 -0500 date -R Mon, 07 Feb 2011 11:03:58 -0500 chmod 755 libtetra-1.0.0/debian/rules debian/rules binary 2>&1 dh_testdir dh_testdir dh_testroot dh_clean -k -d dh_clean: No packages to build. dh_installdirs dh_installdocs dh_installchangelogs find . -maxdepth 1 -mindepth 1 -not -name debian -print0 | \ xargs -0 -r -i cp -a {} debian/ dh_compress dh_makeshlibs dh_installdeb dh_shlibdeps dh_gencontrol dh_md5sums dh_builddeb libtetra_1.0.0-2_i386.deb generated find libtetra-1.0.0 -type d -exec chmod 755 {} ; rm -rf libtetra-1.0.0 Resolution Oh well. It looks like it's perhaps a bug? or I don't know. I simply installed 32-bit version of Ubuntu in VirtualBox and converted package there. For some reason I couldn't convert 32-bit package in 64 OS. and that is that. If someone ever finds the reason ffor this behavior - plz. post somewhere in comments. Thanks

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