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  • How is fundamental mathematics efficiently evaluated by programming languages?

    - by Korvin Szanto
    As I get more and more involved with the theory behind programming, I find myself fascinated and dumbfounded by seemingly simple things.. I realize that my understanding of the majority of fundamental processes is justified through circular logic Q: How does this work? A: Because it does! I hate this realization! I love knowledge, and on top of that I love learning, which leads me to my question (albeit it's a broad one). Question: How are fundamental mathematical operators assessed with programming languages? How have current methods been improved? Example var = 5 * 5; My interpretation: $num1 = 5; $num2 = 5; $num3 = 0; while ($num2 > 0) { $num3 = $num3 + $num1; $num2 = $num2 - 1; } echo $num3; This seems to be highly inefficient. With Higher factors, this method is very slow while the standard built in method is instantanious. How would you simulate multiplication without iterating addition? var = 5 / 5; How is this even done? I can't think of a way to literally split it 5 into 5 equal parts. var = 5 ^ 5; Iterations of iterations of addition? My interpretation: $base = 5; $mod = 5; $num1 = $base; while ($mod > 1) { $num2 = 5; $num3 = 0; while ($num2 > 0) { $num3 = $num3 + $num1; $num2 = $num2 - 1; } $num1 = $num3; $mod -=1; } echo $num3; Again, this is EXTREMELY inefficient, yet I can't think of another way to do this. This same question extends to all mathematical related functions that are handled automagically.

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  • Brain Teaser: How Did I Do This (Part 1: The Solution)

    - by Geertjan
    In Part 1: The Challenge, published this time last week, I introduced a "brain teaser". The brain teaser asks you to figure out how to allow images and other files to be meaningfully dropped onto a NetBeans Platform application, i.e., on the drop something useful should happen with the dropped file: if the file is an image, the image should open in the IDE; if the file is a PDF document, the PDF viewer should open externally; if the file is a text file, it should open as a text in the IDE, etc. Solution. And here is the solution: http://bits.netbeans.org/dev/javadoc/org-openide-windows/org/openide/windows/ExternalDropHandler.html When an implementation of the "ExternalDropHandler" class is available in the global Lookup, and an object is being dragged over some part of the main window, the window system may call the methods of this class to decide whether it can accept or reject the drag operation. And when the object is actually dropped, this class will be asked to handle the drop. OK, so go ahead and implement the above class and put it into the Lookup. Or... guess what? The NetBeans Platform has a default implementation of the above class, appropriately named "DefaultExternalDropHandler". Not only is this useful to learn about how to implement the ExternalDropHandler class (i.e., by reading the source here): you can simply include the module that contains this class in your own NetBeans Platform application and then your application will be able to receive external drag/drop events and do something meaningful with them thanks to the DefaultExternalDropHandler. Do this: Open your NetBeans Platform application in NetBeans IDE. Right-click the application in the Projects window and choose Properties. In the Libraries tab, expand the "ide" cluster, and select "User Utilities". (That's where "DefaultExternalDropHandler.java" is found and registered in the Lookup.) Now click the "Resolve" button, if it appears, because some additional related modules need to now be included, if they haven't been included yet. Again in the "ide" cluster in the Libraries tab, select "Image". That's the Image Editor. Click OK. Run the application. Drag an image or some other type of file into your application, from outside the application, and you'll see the application tries to handle the drop. If the file being dragged is an image, it will open in the Image Editor, which you included in the previous step of these instructions. Hurray, you're done. Without any programming at all, you've added a cool new feature to your application.

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  • Watch ON-Demand Oracle's 4th Annual Primavera Virtual Summit

    - by Melissa Centurio Lopes
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} Did you miss Oracle's 4th Annual Primavera Virtual Summit? Or, maybe you attended the virtual event live, but want to re-watch some presentations or download industry-specific assets - well you can! Watch and visit here, on-demand.  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} This event is now available On-Demand for your convenience. Feel free to log-in anytime to listen again about: New cloud based PPM solutions presentations. Special Primavera Roadmap presentation- what's new and what's coming. Customer stories highlighting their successes with Primavera Unifier, Oracle Instantis and Primavera P6 Enterprise Project Portfolio Management. And don't forget to visit the Resource Library to check out all the latest product information, whitepapers, and demos which are all available to download and read at your convenience. During your visit to the Virtual Summit ON-Demand, we would appreciate you visiting the Networking Lounge and taking a few minutes to fill out the survey. We would really like to hear what you think. You can also visit the Primavera Website for more information about the newest EPPM solutions and offerings.

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  • "You are missing the following 32-bit libraries, and Steam may not run: libc.so.6" The common fixes don't work,

    - by M_Steam_User
    So I know this is a problem that has been asked around a lot, but I've tried a bunch of solutions with no success. I'm running Ubuntu 12.04 (64 bit), and I just installed it yesterday. This is my first time working with linux. The error is: You are missing the following 32-bit libraries, and Steam may not run: libc.so.6 Things I've tried. First, I had downloaded from the steam website. I uninstalled it, and tried again from the ubuntu software centre. sudo apt-get update sudo apt-get install ia32-libs sudo apt-get upgrade This installed a bunch of the 32 bit libraries, but did not fix the issue. This seems like the major fix for most people. The direct approach of sudo apt-get install libc.so.6 returns this: Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package libc.so.6 E: Couldn't find any package by regex 'libc.so.6' I guess libc.so.6 isn't a package, just a single file or something? I also tried gksudo gedit /etc/ld.so.conf.d/steam.conf Added these two lines, those the second one was all ready in the file, but copied over: /usr/lib32 /usr/lib/i386-linux-gnu/mesa Then executed: sudo ldconfig But nothing seemed to happen, steam still doesn't work. So, I feel like it is more likely that I have the library and steam isn't looking in the right place. One thing I've seen is people usually reference /usr/local/lib/ for your library locations. However, I can't find where to cd into /usr/, it isn't in my home folder. If /usr/ is the home folder, there is only a /.local folder which only has /share, no lib anywhere. Sorry for my linux ignorance. I appreciate any help, I honestly have no idea how to confirm I have the library and point steam to it, or if that is even the right thing to do. Edit: Tried this, not entirely sure what it means ~$ ls -l /lib32/libc* -rwxr-xr-x 1 root root 1721832 Sep 30 11:06 /lib32/libc-2.15.so -rw-r--r-- 1 root root 185928 Sep 30 11:06 /lib32/libcidn-2.15.so lrwxrwxrwx 1 root root 15 Sep 30 11:06 /lib32/libcidn.so.1 -> libcidn-2.15.so -rw-r--r-- 1 root root 34316 Sep 30 11:06 /lib32/libcrypt-2.15.so lrwxrwxrwx 1 root root 16 Sep 30 11:06 /lib32/libcrypt.so.1 -> libcrypt-2.15.so lrwxrwxrwx 1 root root 12 Sep 30 11:06 /lib32/libc.so.6 -> libc-2.15.so

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  • Speed up your Silverlight Debugging for large projects

    - by Aligned
    I'm working on a 5+ year old ASP.NET project that has 74+ projects and we've been adding new Silverlight applications to run in the ASP.NET page islands. My machine at work isn't the most powerful, so I find myself waiting a lot for the whole thing to build. I'm using Visual Studio 2010, so that takes up a lot of resources as well. This causes me to get distracted and I start looking at the news... I need to combat that more :-). I can't get a new machine, that's up to someone else, so I've found a few tricks to help. 1. Only build the Silverlight project you're working with. This will build all referenced projects (you can see these by right clicking and clicking Project Dependencies) and package a new XAP (you can see all the actions in your output build window). Then refresh your page with the Silverlight app and it's up-to-date. 2. I was working with a co-worker (thanks Jordan) who was using the the Debug -> attach to processes window. In the Attach to: row there is a "Select..." button. In the dialog, click "Debug these code types:" and select Silverlight. Hit ok. Then all you need to do is find your process (you might need to click the refresh button). I'm usually debugging in IE, so I select the first one and push "i" on the keyboard. That brings me to the IE windows open. Find the one with type of Silverlight, x86. It is usually directly above one with type of x86 that has the page title for "title". Click attach and watch your output window spit out messages about loading debug symbols and your breakpoints enabled (if this doesn't happen you chose the wrong process, hit stop and try again). Now you can debug the client code as normal, server code requires a full F5 or attaching to the correct process. To improve this even further, bind the menu item to a key stroke. I chose ctrl + x, x. (Tools -> Options -> Keyboard, search for Debug.AttachToProcess, set the shortcut keys globaly and assign). Most of the time I build the project, then hit ctrl + x, x then i, then enter and I'm debugging. The process I want is usually the first IE in the list.

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  • I'm graduating with a Computer Science degree but I don't feel like I know how to program.

    - by wp123
    I'm graduating with a Computer Science degree but I see websites like Stack Overflow and search engines like Google and don't know where I'd even begin to write something like that. During one summer I did have the opportunity to work as a iPhone developer, but I felt like I was mostly gluing together libraries that other people had written with little understanding of the mechanics happening beneath the hood. I'm trying to improve my knowledge by studying algorithms, but it is a long and painful process. I find algorithms difficult and at the rate I am learning a decade will have passed before I will master the material in the book. Given my current situation, I've spent a month looking for work but my skills (C, Python, Objective-C) are relatively shallow and are not so desirable in the local market, where C#, Java, and web development are much higher in demand. That is not to say that C and Python opportunities do not exist but they tend to demand 3+ years of experience I do not have. My GPA is OK (3.0) but it's not high enough to apply to the large companies like IBM or return for graduate studies. Basically I'm graduating with a Computer Science degree but I don't feel like I've learned how to program. I thought that joining a company and programming full-time would give me a chance to develop my skills and learn from those more experienced than myself, but I'm struggling to find work and am starting to get really frustrated. I am going to cast my net wider and look beyond the city I've grown up in, but what have other people in similar situation tried to do? I've worked hard but don't have the confidence to go out on my own and write my own app. (That is, become an indie developer in the iPhone app market.) If nothing turns up I will need to consider upgrading and learning more popular skills or try something marginally related like IT, but given all the effort I've put in that feels like copping out. EDIT: Thank you for all the advice. I think I was premature because of unrealistic expectations but the comments have given me a dose of reality. I will persevere and continue to code. I have a project in mind, although well beyond my current capabilities it will challenge me to hone my craft and prove my worth to myself (and potential employers). Had I known there was a career overflow I would have posted there instead. Thanks again!

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  • Fans running very fast on MacBook Pro 8.1

    - by Tomasz Kacprzak
    I installed Ubuntu 12.04 on Macbook Pro 8.1 and one of the first things I noticed was that the fans were starting to spin very fast every few minutes for 10-30 sec and then going back to normal. That was happening even without any processor load, when completely idle. The fans were usually spinning at 4000 RPM and made much noise. The computer was not getting hotter than usual. When running OSX Lion there was no noise at all, fans almost all the time at 2000 RPM. I spent some time on it and found out that Precise uses a deamon to control the temperature, called macfanctld. You can use /etc/macfanctld.conf to set the configuration. I found out that the high fan speed is not due to the fact that the temperature is getting hot, but because there are two sensors which indicate wrong numbers (you can check that using 'sensors' command ): TW0P: +129.0°C TCTD: +256.0°C TCFC: +0.0°C TMBS: +0.0°C or setting the macfanctld log level to 2: Speed: 4992, *AVG: 56.9C, TC0P: 50.2C, TG0P: 51.5C, Sensors: TB0T:34 TB1T:34 TB2T:33 TC0C:58 TC0D:56 TC0E:59 TC0F:60 TC0P:50 TC1C:58 TC2C:58 TC3C:58 TC4C:57 TCFC:0 TCGC:57 TCSA:53 TCTD:256 TG0D:52 TG0P:52 THSP:42 TM0S:64 TMBS:0 TP0P:54 TPCD:60 TW0P:129 Th1H:51 Th2H:48 Tm0P:40 Ts0P:32 Ts0S:43 Moreover, TCTD was randomly jumping from temperatures of 0 to 256, so this may be the reason for unjustified random fan speeds. macfanctld is taking an average of the sensors including the values above, so the actual AVG temp used to control the fans is wrong, usually biased up, hence high RPM and noise. The workaround solution is to use an option in the macfanctld.conf which allows to ignore the malfunctioning sensors: exclude: 13 16 21 24 After reboot the reported temperatures are usually normal and the fans are working at reasonable speeds. I tested the response of the fans to heavy processor load by asking MATLAB to invert 10000x10000 matrix and the AVG temperature jumped to 63deg, and the fan to max 6200 RPM and then got it back to normal temperature. So I think it is safe so far. There is a expired bug about the failing sensor readings: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/955538 which may be good to open again. My question would be: does anyone know what the failing sensors do and if there is any danger in excluding them? Maybe some better solution to this problem?

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  • Upgrades from Beta or CTP SQL Server Software is NOT Supported

    - by BuckWoody
    As of this writing, SQL Server 2008 R2 has released, and just like every release, I get e-mails and calls from folks with this question: “Can I upgrade from Customer Technical Preview (CTP) x or Beta #x or Release Candidate (RC) to the “Released to Manufacturing” (RTM) version?” No. Right up until the last minute, things are changing in the code – and you want that to happen. Our internal testing runs right up until the second we lock down for release, and we watch the CTP/RC/Beta reports to make sure there are no show-stoppers, and fix what we find. And it’s not just “big” changes you need to worry about – a simple change in one line of code can have a massive effect. I know, I know – you’ve possibly upgraded an RC or CTP to the RTM version and it worked “just fine”. But hear this tale: I’ve dealt with someone who faced this exact situation in SQL Server 2008. They upgraded (which is clearly prohibited in the documentation) from a CTP to the RTM version over a year ago. Everything was working fine. But then…one day they had an issue. Couldn’t fix it themselves, we took a look, days went by, and we finally had to call in the big guns for support. Turns out, the upgrade was the problem. So we had to come up with some elaborate schemes to get the system migrated over while they were in production. This was painful for everyone involved. So the answer is still no. Just don’t do it. There is one caveat to this story – if you are a “TAP” customer (you’ll know if you are), we help you move from the CTP products to RTM, but that’s a special case that we track carefully and send along special instructions and tools to help you along. That level of effort isn’t possible on a large scale, so it’s not just a magic tool that we run to upgrade from CTP to RTM. So again, unless you’re a TAP customer, it’s a no-no. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • What is a useful pattern to maintaining an object state in a one to many relationship?

    - by ahenderson
    I am looking for a design for my application, here are the players(classes) involved. struct Transform { // Uses a matrix to transform the position. // Also acts acts as the state of a Dialog. Position transform(Position p); //other methods. }; struct Dialog { // There are multiple dialog for the user to transform the output. Transform& t; void ChangeTranformation(){t.rotate(360);} } struct Algorithm { //gives us a position based on an implementation. For example this can return points on a circle or line. Transform& t; Position m_p; Dialog& d; Position GetCurrentPosition(){ return t.transform(m_p);} //other methods. } Properties I need: Each algorithms has one dialog and each dialog can have many algorithms associated with it. When the user selects an algorithm a dialog associated with that algorithm is displayed. If the user selects a different algorithm then re-selects back the state is restored in the dialog. Basically I want a good design pattern to maintain the state of the dialog given that many algorithms use it and they can be switched back and forth. Does anyone have any suggestions? Here is a use case: Dialog1 has a single edit box to control the radius. Algorithm1 generates points on a unit circle. Algorithm2 is the same as Algorithm1. The user has selected Algorithm1 and entered 2 into the edit box. This will generate points on a circle of radius 2. The user then selects Algorithm2 and enters 10 into the edit box of Dialog1. This will generate points on a circle of radius 10. Finally Algorithm1 is selected again. The edit box of Dialog1 should show 2 and points on a circle of radius 2 should be generated.

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  • Threads slowing down application and not working properly

    - by Belgin
    I'm making a software renderer which does per-polygon rasterization using a floating point digital differential analyzer algorithm. My idea was to create two threads for rasterization and have them work like so: one thread draws each even scanline in a polygon and the other thread draws each odd scanline, and they both start working at the same time, but the main application waits for both of them to finish and then pauses them before continuing with other computations. As this is the first time I'm making a threaded application, I'm not sure if the following method for thread synchronization is correct: First of all, I use two global variables to control the two threads, if a global variable is set to 1, that means the thread can start working, otherwise it must not work. This is checked by the thread running an infinite loop and if it detects that the global variable has changed its value, it does its job and then sets the variable back to 0 again. The main program also uses an empty while to check when both variables become 0 after setting them to 1. Second, each thread is assigned a global structure which contains information about the triangle that is about to be rasterized. The structures are filled in by the main program before setting the global variables to 1. My dilemma is that, while this process works under some conditions, it slows down the program considerably, and also it fails to run properly when compiled for Release in Visual Studio, or when compiled with any sort of -O optimization with gcc (i.e. nothing on screen, even SEGFAULTs). The program isn't much faster by default without threads, which you can see for yourself by commenting out the #define THREADS directive, but if I apply optimizations, it becomes much faster (especially with gcc -Ofast -march=native). N.B. It might not compile with gcc because of fscanf_s calls, but you can replace those with the usual fscanf, if you wish to use gcc. Because there is a lot of code, too much for here or pastebin, I created a git repository where you can view it. My questions are: Why does adding these two threads slow down my application? Why doesn't it work when compiling for Release or with optimizations? Can I speed up the application with threads? If so, how? Thanks in advance.

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  • Operation times out trying to SSH outside LAN i.e. from internet to LAN no connection is established

    - by Pelle L
    I run Ubuntu 12.04 and have no success connecting with SSH from "Internet". The router is a TL-MR3420 which is set up to forward requests to one of the NIC's on ubuntu machine (which has in total 3 NICs). I can SSH from a client on the "local" network/LAN. The forward mechanism in the router seems to work. If I stop SSH service on the Ubuntu machine and instead start one on the windows machine - it works like a charm. I do not use the Std port 22 but that shouldn't be an issue as far as I understand - sine it works on the same port on the win machine. Since my public IS isn't static I use a dynDNS service but as said earlier the same setup works from the win machine. The router is located on 192.168.0.1 The Ubuntu NICs has the following IP: eth2 192.168.0.100 , eth1 192.168.0.101 , eth0 192.168.0.102 and I have forwarded the "outside" request to 192.168.0.100 In regards for firewall settings on the Ubuntu machine I have disabled the ufw and the command ufw status give status: inactive. I don't now it this is relevant information but teh command iptables --list give: Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination I have tried to catch traffic with help of wireshark (a tool I'm not too used to use) and it seems as a few (3?) "requests" actually reaches the NIC but ... nothing happens. The syslog does not show any entries during these attempts. Perhaps it could be some routing issues but I have reached my level of competence and are stuck ... all help and support to get this sorted out is much appreciated. I'm new to Linux so please do not assume I have a configuration that is correct - but as I wrote earlier - if the client that initiate SSH is on the LAN it all works. PS:I have also tried to get VPN (PPP) working from Internet with no success - once again VPN works on the windows machine ... so my best guess is that this is related to how the ubuntu machine handles (IP) traffic and not the TL-MR3420 router or other network issues.

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  • How to properly document functionality in an agile project?

    - by RoboShop
    So recently, we've just finished the first phase of our project. We used agile with fortnightly sprints. And whilst the application turned out well, we're now turning our eyes on some of the maintenance tasks. One maintenance task is that all of our documentation appears in the form of specs. These specs describe 1 or more stories and generally are a body of work which a few devs could knock over in a week. For development, that works really well - every two weeks, the devs get handed a spec and it's a nice discrete chunk of work that they can just do. From a documentation point of view, this has become a mess. The problem with writing specs that are focused on delivering just-in-time requirements to developers is we haven't placed much emphasis on the big picture. Specs come from all different angles - it could be describing a standard function, it could describing parts of a workflow, it could be describing a particular screen... And now, we have business rules about our application scattered across 120 documents. Looking for any document for a particular business rule or function in particular is quite hard because you don't know which document has this information, and making a change request is equally hard because once again, we are unsure about which spec to make the change. So we have maybe a couple of weeks of lull before it's back to specing out functionality for the next phase but in this time, I'd like to re-visit our processes. I think the way we have worked so far in terms of delivering fortnightly specs works well. But we also need a way to manage our documentation so that our business rules for a given function / workflow are easy to locate / change. I have two ideas. One is we compile all of our specs into a series of master specs broken by a few broad functional areas. The specs describe the sprint, the master spec describe the system. The only problem I can see is 1) Our existing 120 specs are not all neatly defined into broad functional areas. Some will require breaking up, merging etc. which will take a lot of time. 2) We'll be writing specs and updating master specs in each new sprint. Seems like double the work, and then do the devs look at the spec or the master spec? My other suggestion is to concede that our documentation is too big of a mess, and manage that mess going forward. So we go through each spec, assign like keywords to it, and then when we want to search for a function, we search for that keyword. Problems I can see 1) Still the problem of business rules scattered everywhere, keywords just make it easier to find it. anyway, if anyone has any decent ideas or any experience to share about how best to manage documentation, would really appreciate it.

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  • MySQL Connector/Net 6.6.4 RC1 has been released

    - by fernando
    MySQL Connector/Net 6.6.4, a new version of the all-managed .NET driver  for MySQL has been released.  This is the Release Candidate intended to introduce users to the new features in the release.  This release is feature complete it should be stable enough for users to understand the new features and how we expect them to work.  As is the case with all non-GA releases, it should not be used in any production environment.  It is appropriate for use with MySQL server versions 5.0-5.6 It is now available in source and binary form from http://dev.mysql.com/downloads/connector/net/#downloads and mirror sites (note that not all mirror sites may be up to date at this point-if you can't find this version on some mirror, please try again later or choose another download site.) The 6.6 version of MySQL Connector/Net brings the following new features:   * Stored routine debugging   * Entity Framework 4.3 Code First support   * Pluggable authentication (now third parties can plug new authentications mechanisms into the driver).   * Full Visual Studio 2012 support: everything from Server Explorer to Intellisense&  the Stored Routine debugger. The following specific fixes are addressed in this version: - Fixed Entity Framework + mysql connector/net in partial trust throws exceptions (MySql bug #65036, Oracle bug #14668820). - Added support in Parser for Datetime and Time types with precision when using Server 5.6 (No bug Number). - Fix for bug TIMESTAMP values are mistakenly represented as DateTime with Kind = Local (Mysql bug #66964, Oracle bug #14740705). The release is available to download athttp://dev.mysql.com/downloads/connector/net/6.6.html Documentation ------------------------------------- You can view current Connector/Net documentation at http://dev.mysql.com/doc/refman/5.5/en/connector-net.html For specific topics: Stored Routine Debugger:http://dev.mysql.com/doc/refman/5.5/en/connector-net-visual-studio-debugger.html Authentication plugin:http://dev.mysql.com/doc/refman/5.5/en/connector-net-programming-authentication-user-plugin.html You can find our team blog at http://blogs.oracle.com/MySQLOnWindows. You can also post questions on our forums at http://forums.mysql.com/. Enjoy and thanks for the support!

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  • Does OO, TDD, and Refactoring to Smaller Functions affect Speed of Code?

    - by Dennis
    In Computer Science field, I have noticed a notable shift in thinking when it comes to programming. The advice as it stands now is write smaller, more testable code refactor existing code into smaller and smaller chunks of code until most of your methods/functions are just a few lines long write functions that only do one thing (which makes them smaller again) This is a change compared to the "old" or "bad" code practices where you have methods spanning 2500 lines, and big classes doing everything. My question is this: when it call comes down to machine code, to 1s and 0s, to assembly instructions, should I be at all concerned that my class-separated code with variety of small-to-tiny functions generates too much extra overhead? While I am not exactly familiar with how OO code and function calls are handled in ASM in the end, I do have some idea. I assume that each extra function call, object call, or include call (in some languages), generate an extra set of instructions, thereby increasing code's volume and adding various overhead, without adding actual "useful" code. I also imagine that good optimizations can be done to ASM before it is actually ran on the hardware, but that optimization can only do so much too. Hence, my question -- how much overhead (in space and speed) does well-separated code (split up across hundreds of files, classes, and methods) actually introduce compared to having "one big method that contains everything", due to this overhead? UPDATE for clarity: I am assuming that adding more and more functions and more and more objects and classes in a code will result in more and more parameter passing between smaller code pieces. It was said somewhere (quote TBD) that up to 70% of all code is made up of ASM's MOV instruction - loading CPU registers with proper variables, not the actual computation being done. In my case, you load up CPU's time with PUSH/POP instructions to provide linkage and parameter passing between various pieces of code. The smaller you make your pieces of code, the more overhead "linkage" is required. I am concerned that this linkage adds to software bloat and slow-down and I am wondering if I should be concerned about this, and how much, if any at all, because current and future generations of programmers who are building software for the next century, will have to live with and consume software built using these practices. UPDATE: Multiple files I am writing new code now that is slowly replacing old code. In particular I've noted that one of the old classes was a ~3000 line file (as mentioned earlier). Now it is becoming a set of 15-20 files located across various directories, including test files and not including PHP framework I am using to bind some things together. More files are coming as well. When it comes to disk I/O, loading multiple files is slower than loading one large file. Of course not all files are loaded, they are loaded as needed, and disk caching and memory caching options exist, and yet still I believe that loading multiple files takes more processing than loading a single file into memory. I am adding that to my concern.

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  • Unintentional run-in with C# thread concurrency

    - by geekrutherford
    For the first time today we began conducting load testing on a ASP.NET application already in production. Obviously you would normally want to load test prior to releasing to a production environment, but that isn't the point here.   We ran a test which simulated 5 users hitting the application doing the same actions simultaneously. The first few pages visited seemed fine and then things just hung for a while before the test failed. While the test was running I was viewing the performance counters on the server noting that the CPU was consistently pegged at 100% until the testing tool gave up.   Fortunately the application logs all exceptions including those unhandled to the database (thanks to log4net). I checked the log and low and behold the error was:   System.ArgumentException: An item with the same key has already been added. (The rest of the stack trace intentionally omitted)   Since the code was running with debug on the line number where the exception occured was also provided. I began inspecting the code and almost immediately it hit me, the section of code responsible for the exception is trying to initialize a static class. My next question was how is this code being hit multiple times when I have a rudimentary check already in place to prevent this kind of thing (i.e. a check on a public variable of the static class before entering the initializing routine). The answer...the check fails because the value is not set before other threads have already made it through.   Not being one who consistently works with threading I wasn't quite sure how to handle this problem. Fortunately a co-worker recalled having to lock a section of code in the past but couldn't recall exactly how. After a quick search on Google the solution is as follows:   Object objLock = new Object(); lock(objLock) { //logic requiring lock }   The lock statement takes an object and tells the .NET runtime that the current thread has exclusive access while the code within brackets is executing. Once the code completes, the lock is released for another thread to utilize.   In my case, I only need to execute the inner code once to initialize my static class. So within the brackets I have a check on a public variable to prevent it from being initialized again.

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  • Should we persist with an employee still writing bad code after many years?

    - by user94986
    I've been assigned the task of managing developers for a well-established company. They have a single developer who specialises in all their C++ coding (since forever), but the quality of the work is abysmal. Code reviews and testing have revealed many problems, one of the worst being memory leaks. The developer has never tested his code for leaks, and I discovered that the applications could leak many MBs with only a minute of use. User's were reporting huge slowdowns, and his take was, "it's nothing to do with me - if they quit and restart, it's all good again." I've given him tools to detect and trace the leaks, and sat down with him for many hours to demonstrate how the tools are used, where the problems occur, and what to do to fix them. We're 6 months down the track, and I assigned him to write a new module. I reviewed it before it was integrated into our larger code base, and was dismayed to discover the same bad coding as before. The part that I find incomprehensible is that some of the coding is worse than amateurish. For example, he wanted a class (Foo) that could populate an object of another class (Bar). He decided that Foo would hold a reference to Bar, e.g.: class Foo { public: Foo(Bar& bar) : m_bar(bar) {} private: Bar& m_bar; }; But (for other reasons) he also needed a default constructor for Foo and, rather than question his initial design, he wrote this gem: Foo::Foo() : m_bar(*(new Bar)) {} So every time the default constructor is called, a Bar is leaked. To make matters worse, Foo allocates memory from the heap for 2 other objects, but he didn't write a destructor or copy constructor. So every allocation of Foo actually leaks 3 different objects, and you can imagine what happened when a Foo was copied. And - it only gets better - he repeated the same pattern on three other classes, so it isn't a one-off slip. The whole concept is wrong on so many levels. I would feel more understanding if this came from a total novice. But this guy has been doing this for many years and has had very focussed training and advice over the past few months. I realise he has been working without mentoring or peer reviews most of that time, but I'm beginning to feel he can't change. So my question is, would you persist with someone who is writing such obviously bad code?

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  • Is multiple domain names and links from same IP causing poor search engine rankings?

    - by John
    I have an ecommerce website which is not doing so well in Google. I am trying to improve this of course, and am looking at some possibilities for why it isn't doing well. The website has four domain names, all of which have been indexed by Google. A few months ago I applied 301 redirects to any requests for two of the domain names so now it is down to two domain names (one is a .net, the other is a .com.au, the others were .net.au and .com). I prefer to use my main domain name (the .com.au), but one of the names has been around for a long time and has more inbound links. According to a PageRank tool, both are PR2. It is a Classic ASP site and up until recently had a lot of querystring parameters. In the last week or so I added URL rewriting so there is now no parameters for most pages. I don't do 301 redirects from the old URLs but instead I add the META canonical tag indicating the preferred new URL. At the same time I redesigned the site and improved title tags, META descriptions, and H tags but it hasn't been long enough yet for Google to index many of these yet. I also looked at what pages Google has indexed and strangely it has some strange pages in the index, there are a lot of pages which are actual keyword searches (more a bunch of random letters than an actual word). What I mean is that it is as if they had typed in something to search for in my search box - there are no links to pages like this and the only way of getting this is to type something in to the search box). So I added a META robots tag with noindex,nofollow anytime that I render pages like this. Years ago I set up a fake price comparison site which lists all my products and links back to my site. It has a different keyword rich domain name but is on the same server and same IP address. It's a completely different layout but does have the same product categories and product descriptions (although I have stripped formatting out of them so they are not identical except in text). I also have a few blog sites which again are on the same server/IP and all have advertising for the website. My questions are: What should I do with the multiple domains, just use one, or continue with two or more? Should I add 301 redirects, not just the META canonical tag? Any idea about Google indexing my search results page, and did I do the right thing with the META robots tag? Is the fake price comparison site likely to be causing problems? Are all the links to the site from other domain names but the same IP address likely to be causing problems? Thanks for any help. Sorry for so many questions in one.

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  • dual boot ubuntu installation mishap

    - by user590849
    I have Windows 7 pc ,where i had 2 partitions, a c drive for my system files and a d drive for my data. I decided to install ubuntu 11.10 a couple of days ago and thought of install it in a separate partition of its own. So i made a separate Linux partition of 30GB. I downloaded ubuntu on my usb stick and installed. During the installation process i was asked where to install ubuntu so i opened up a screen that was similar to this one There were six partitions present ( I had made only 3 partition via windows). Their names were totally different from the ones that i had given in windows. So i selected a drive which had the same size as my Linux partition that i had made in windows ( no other partition had the same size). I clicked on install now and got an error message saying that "There was no root folder set". I set the newly made partition as my root folder and clicked install now. Now out of the 6 partitions that were created 3 were logical ( i had only created 3 partitions in windows). As soon as i clicked install now, the system asked me where i wanted to put my "swap space". I selected one of the logical drives and hit install. Ubuntu successfully installed on my system and at the end it asked me to reboot. I did and got the following error message: "missing operating system". I was shocked. I tried my windows recovery disk ( that i had gotten when i had purchased my laptop) and there i went into startup repair. In the startup repair option i was not able to locate windows. The system asked me to click the "Load drivers" button to load the drivers to my harddrive where windows was installed, but i could not locate any drivers to my harddrive. I tried this several times but to no success. I panicked and installed ubuntu, now this time click "ok" at every step( not worrying about the partition and all). The os installed correctly and i am now able to access my harddrive. NO data within the c drive is lost. All the windows system files are intact. I wish to recover my windows installation. How do i go about it? Thank you in advance. I do not want to format my computer and install windows again.

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  • Help with DB Structure, vOD site

    - by Chud37
    I have a video on demand style site that hosts series of videos under different modules. However with the way I have designed the database it is proving to be very slow. I have asked this question before and someone suggested indexing, but i cannot seem to get my head around it. But I would like someone to help with the structure of the database here to see if it can be improved. The core table is Videos: ID bigint(20) (primary key, auto-increment) pID text airdate text title text subject mediumtext url mediumtext mID int(11) vID int(11) sID int(11) pID is a unique 5 digit string to each video that is a shorthand identifier. Airdate is the TS, (stored in text format, right there maybe I should change that to TIMESTAMP AUTO UPDATE), title is self explanatory, subject is self explanatory, url is the hard link on the site to the video, mID is joined to another table for the module title, vID is joined to another table for the language of the video, (english, russian, etc) and sID is the summary for the module, a paragraph stored in an external database. The slowest part of the website is the logging part of it. I store the data in another table called 'Hits': id mediumint(10) (primary key, auto-increment) progID text ts int(10) Again, here (this was all made a while ago) but my Timestamp (ts) is an INT instead of ON UPDATE CURRENT TIMESTAMP, which I guess it should be. However This table is now 47,492 rows long and the script that I wrote to process it is very very slow, so slow in fact that it times out. A row is added to this table each time a user clicks 'Play' on the website and then so the progID is the same as the pID, and it logs the php time() timestamp in ts. Basically I load the entire database of 'Hits' into an array and count the hits in each day using the TS column. I am guessing (i'm quite slow at all this, but I had no idea this would happen when I built the thing) that this is possibly the worst way to go about this. So my questions are as follows: Is there a better way of structuring the 'Videos' table, is so, what do you suggest? Is there a better way of structuring 'hits', if so, please help/tell me! Or is it the fact that my tables are fine and the PHP coding is crappy?

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  • Registering domain during Christmas holidays

    - by arkascha
    One of the domain names I tried to register previously has been blocked by a domain grabber two days prior to my own attempt. That was about 1 year ago. The attempt to buy the domain from that person failed due to a totally exaggerated price. So I dropped the issue and watched the domain (offered at sedo.com). As expected there were no more offers, the domain was not sold. Now I learn from the whois database that the registration of that domain name ends on 25 Dec 2012 (Christmas holiday). This raises two questions for me, I fail to find reliable answers on the internet. So maybe someone experienced here can drop a statement or a hint: Is it reasonable that the domain name in question really will be free again when that date mentioned in the whois database up to when the domain is registered has passed? I certainly know that the registration can be prolonged, that is not what I mean. I expect (hope) that that domain grabber does not extend the registration, since it costs money and effort and he failed to sell the domain. Provided this is the case and the domain registration is not prolonged, is that date mentioned reliable? Or might it just be some 'default' date? I would like to try to register that domain name as soon as it is unregistered. Since that domain grabber registered that domain only two days before my own registration attempt I would like to prevent such annoying interference next time. So I ask myself: is it possible to register a domain name on a holiday? I mean not to send an email to my provider to do so on that day or before, but to actually have to process taking place as not to wait for 1-2 days after the unregistration? My own provider which I am very happy with does not offer such service on a holiday (which is perfectly understandable). They are 'still checking' if they can offer something automatic. I researched and did not find an answer to the question if that is possible at all. Is an automatic registration attempt on a holiday possible? Where can I do that? Is that reliable?

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  • Silverlight and WCF caching

    - by subodhnpushpak
    There are scenarios where Silverlight client calls WCF (or REST) service for data. Now, if the data is cached on the WCF layer, the calls can take considerable resources at the server if NOT cached. Keeping that in mind along with the fact that cache is an cross-cutting aspect, and therefore it should be as easy as possible to put Cache wherever required. The good thing about the solution is that it caches based on the inputs. The input can be basic type of any complex type. If input changes the data is fetched and then cached for further used. If same input is provided again, data id fetched from the cache. The cache logic itself is implemented as PostSharp aspect, and it is as easy as putting an attribute over service call to switch on cache. Notice how clean the code is:        [OperationContract]       [CacheOnArgs(typeof(int))] // based on actual value of cache        public string DoWork(int value)        {            return string.Format("You entered: {0} @ cached time {1}", value, System.DateTime.Now);        } The cache is implemented as POST Sharp as below 1: public override void OnInvocation(MethodInvocationEventArgs eventArgs) 2: { 3: try 4: { 5: object value = new object(); 6: object[] args = eventArgs.GetArgumentArray(); 7: if (args != null || args.Count() > 0) 8: { 9:   10: string key = string.Format("{0}_{1}", eventArgs.Method.Name, XMLUtility<object>.GetDataContractXml(args[0], null));// Compute the cache key (details omitted). 11:   12: 13: value = GetFromCache(key); 14: if (value == null) 15: { 16: eventArgs.Proceed(); 17: value = XMLUtility<object>.GetDataContractXml(eventArgs.ReturnValue, null); 18: value = eventArgs.ReturnValue; 19: AddToCache(key, value); 20: return; 21: } 22:   23:   24: Log(string.Format("Data returned from Cache {0}",value)); 25: eventArgs.ReturnValue = value; 26: } 27: } 28: catch (Exception ex) 29: { 30: //ApplicationLogger.LogException(ex.Message, Source.UtilityService); 31: } 32: } 33:   34: private object GetFromCache(string inputKey) { if (ServerConfig.CachingEnabled) { return WCFCache.Current[inputKey]; } return null; }private void AddToCache(string inputKey,object outputValue) 35: { 36: if (ServerConfig.CachingEnabled) 37: { 38: if (WCFCache.Current.CachedItemsNumber < ServerConfig.NumberOfCachedItems) 39: { 40: if (ServerConfig.SlidingExpirationTime <= 0 || ServerConfig.SlidingExpirationTime == int.MaxValue) 41: { 42: WCFCache.Current[inputKey] = outputValue; 43: } 44: else 45: { 46: WCFCache.Current.Insert(inputKey, outputValue, new TimeSpan(0, 0, ServerConfig.SlidingExpirationTime), true); 47:   48: // _bw.DoWork += bw_DoWork; 49: //string arg = string.Format("{0}|{1}", inputKey,outputValue); 50: //_bw.RunWorkerAsync(inputKey ); 51: } 52: } 53: } 54: }     The cache class can be extended to support Velocity / memcahe / Nache. the attribute can be used over REST services as well. Hope the above helps. Here is the code base for the same.   Please do provide your inputs / comments.

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  • Curating projects of deceased friends

    - by Ant
    A very good friend of mine, and an avid programmer, recently passed away. He left nearly 40 projects on BitBucket. Most of them are public, but a few of them are marked as private. I've decided to take on curation duties for the projects rather than leave his work to disappear. If you have been in the same situation, what did you do? Did you open-source everything? Continue development? Delete it all? I'm very interested to hear other people's experiences. There are a few reasons why some of the projects are marked as private (private projects on BitBucket are visible only to invited users and the original creator): One of them is an iOS web app that was free in the app store. I've had to remove the app from the store as I'm shutting down his web sites as a favour to his widow. However, I've already made the app public under the GPL v3 (he was a big GPL supporter). One of them contains proprietary code. It can't be open-sourced. Others are very much work-in-progress. I don't know if he intended to make them into hosted, paid services or if he wanted to give the code away under an open-source licence when they were finished. Here's a list of the private projects: Some kind of living cell simulator that uses SBML along with Runge-Kutta and Euler algorithms to do... something. There's a fair amount of code here but I don't know what it does or how far along it is. No docs. An accountacy application; it seems to have a solid DB design behind it but there's little code on top of that. A website whose purpose is to suggest good restaurants. Built on yii. Seems to have a lot of code but I'd need to set up a WAMP stack to see how far along it is. A website intended to host memorials to people who suffered from the same problem he was. Built on Joomla. I'm not sure how much of the code is just Joomla and how much is custom; again, I'd need to get Joomla running to find out. I'd just introduced him to Mercurial and BitBucket. All of the private projects are single commits of codebases he wasn't using version control with/was previously using SVN. I don't have the SVN repositories so I can't see the commit logs.

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  • how did Google Analytics kill my site?

    - by user1813359
    Yesterday I created a google analytics profile for one of my sites and included the JS block in the layout template. What happened next was very strange. Within about 2 minutes, the site had become unreachable. I had been checking the AWStats page for the site when I thought to set up GA. After that had been done, I clicked on the link for 404 stats, which opens in a new tab. It churned for a long while and then showed a nearly blank page, similar to that when Firefox chokes on a badly-formatted XML page, except there was no error msg. But i was logged into the server and could see that that page has a 401 Transitional DTD. Strange! I tried viewing source but it just churned endlessly. I then tried "inspect element" and was able to see an error msg having to do with some internal Firefox lib. Unfortunately, i neglected to copy that. :-( All further attempts to load anything on the site would time out. Firebug's Net panel showed no request being made. Chrome would time out. So, I deleted the GA profile, removed the JS block, and cleared the server cache. No joy. I then removed all google cookies and disabled JS. Still nothing. No luck in any other browser. And now my client couldn't access the site. Terrific. I was able use wget while logged into another server. The retrieved page was fine, and did not contain the GA JS block. However, the two servers are on the same network. (Perhaps a clue.) The server itself was fine. Ping, traceroute looked great. I could SSH in. I tailed the access log and tried a browser request. Nothing. But i forgot to quit and a minute or so later I saw a request from someone else being logged. Later, I could see that requests had been served all day to some people. Now, 24 hours later, the site works once again, but is still unreachable by the client (who is in another city). So, does anyone have some insight into what's going on? Does this have something to do with google's CDN? I don't know very much about how GA works but what I'm seeing reminds me of DNS propagation issues. And why the initial XML error? And why the heck was the site just plain unreachable? What did google do to my site?! Sorry for the length but I wanted to cover everything.

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  • From 20,663 issues to 1 issue&ndash;style-copping C5.Tests

    - by TATWORTH
    Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2014/05/28/from-20663-issues-to-1-issuendashstyle-copping-c5.tests.aspxI recently became interested in the potential of the C5 Collections solution from http://www.itu.dk/research/c5/, however I was dismayed at the state of the code in the unit test project, so I set about fixing the 20,663 issues detected by StyleCop. The tools I used were the latest versions of: My 64-bit development PC running Windows 8 Update with 8Gb RAM Visual Studio 2013 Ultimate with SP2 ReSharper GhostDoc Pro My first attempt had to be abandoned due to collision of class names which broke one of the unit tests. So being aware of this duplication of class names, I started again and planned to prepend the class names with the namespace name. In some cases I additionally prepended the item of the C5 collection that was being tested. So what was the condition of code at the start? Besides the sprawl of C# code not written to style cop standard, there was: 1) Placing of many classes within one physical file. 2) Namespace within name space that did not follow the project structure. 3) As already mentioned, duplication of class names across namespaces. 4) A copyright notice that spawled but had to be preserved. 5) Project sub-folders were all lower case instead of initial letter capitalised. The first step was to add a stylecop heading plus the original heading contained within a region, to every file. The next step was to run GhostDoc Pro using its “Document File” option on every file but not letting it replace the headers, I had added. This brought the number of issues down to 18,192. I then went through each file collapsing each class and prepending names as appropriate. At each step, I saved the changes to my local Git. The step was to move each class to its own file and to style-cop each file. ReSharper provides a very useful feature for doing this which also fixes missing “this.” and moves using statements inside the namespace. Some classes required minimal work whereas others required extensive work to reach the stylecop standard. The unit tests were run at each split and when each class was completed. When all was done, one issue remained which I will need to submit to stylecop team for their advice (and possibly a fix to stylecop). The updated solution has been made available at https://c5stylecopped.codeplex.com/releases/view/122785.

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  • How do I server multiple domains from the same directory and codebase without my configuraton breaking when apache.conf is overwritten?

    - by neokio
    I have 20 domains on a VPS running cPanel. One public_html is filled with code, the remaining 19 are symbolic links to that one. (For example, assets is a directory within public_html ... for the 19 others, there's a symbolic link to that directory in each each accounts public_html dir.) It's all PHP / MySQL database driven, with content changing depending on the domain. It works like a charm, assuming cPanel has suExec enabled correctly, and assuming apache.conf does NOT have SymLinksIfOwnerMatch enabled. However, every few weeks, my apache.conf is mysteriously overwritten, re-enabling SymLinksIfOwnerMatch, and disabling all 19 linked sites for as long as it takes for me to notice. Here's the offending line in apache.conf: <Directory "/"> AllowOverride All Options ExecCGI FollowSymLinks IncludesNOEXEC Indexes SymLinksIfOwnerMatch </Directory> The addition of SymLinksIfOwnerMatch disables the sites in a strange way ... the html is generated correctly, but all css/js/image in the html fails to load. Clicking any link redirects to /. And I have no idea why. I do have a few things in my .htaccess, which work fine when SymLinksIfOwnerMatch is not present: <IfModule mod_rewrite.c> # www.example.com -> example.com RewriteCond %{HTTPS} !=on RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC] RewriteRule ^ http://%1%{REQUEST_URI} [R=301,L] # Remove query strings from static resources RewriteRule ^assets/js/(.*)_v(.*)\.js /assets/js/$1.js [L] RewriteRule ^assets/css/(.*)_v(.*)\.css /assets/css/$1.css [L] RewriteRule ^assets/sites/(.*)/(.*)_v(.*)\.css /assets/sites/$1/$2.css [L] # Block access to hidden files and directories RewriteCond %{SCRIPT_FILENAME} -d [OR] RewriteCond %{SCRIPT_FILENAME} -f RewriteRule "(^|/)\." - [F] # SLIR ... reroute images to image processor RewriteCond %{REQUEST_URI} ^/images/.*$ RewriteRule ^.*$ - [L] # ignore rules if URL is a file RewriteCond %{REQUEST_FILENAME} !-f # ignore rules if URL is not php #RewriteCond %{REQUEST_URI} !\.php$ # catch-all for routing RewriteRule . index.php [L] </ifModule> I also use most of the 5G Blacklist 2013 for protection against exploits and other depravities. Again, all of this works great, except when SymLinksIfOwnerMatch gets added back into apache.conf. Since I've failed to find the cause of whatever cPanel/security update is overwriting apache.conf, I thought there might be a more correct way to accomplish my goal using group permissions. I've created a 'www' group, added all accounts to the group, and chmod -R'd the code source to use that group. Everything is 644 or 755. But doesn't seem to be enough. My unix isn't that strong. Do you need to restart something for group changes to take effect? Probably not. Anyways, I'm entering unknown territory. Can anyone recommend the right way to configure a website for multiple sites using one codebase that doesn't rely on apache.conf?

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