Search Results

Search found 1769 results on 71 pages for 'architechture concepts'.

Page 61/71 | < Previous Page | 57 58 59 60 61 62 63 64 65 66 67 68  | Next Page >

  • Computer Science taxonomy

    - by Bakhtiyor
    I am developing web application where users have collection of tags. I need to create a suggestion list for users based on the similarity of their tags. For example, when a user logs in to the system, system gets his tags and search these tags in the DB of users and showing users who have similar tags. For instance if User 1 has following tags [Linux, Apache, MySQL, PHP] and User 2 has [Windows, IIS, PHP, MySQL] it says that User 2 matchs User 1 with a weight of 50%, because he has 2 similar tags(PHP and MySQL). But imagine the situation where User 1 has [ASP, IIS, MS Access] and User 2 has [PHP, Apache, MySQL]. In this situation my system doesn't suggest User 2 as a "friend" to User 1 or vice versa. But we now that these two users has similarity on the the field of work, both works on Web Technology (or Web Programming, etc). So, that is why I need kind of taxonomy of computer science (right now, but probably I would need taxonomy of other fields also, like medicine, physics, mathematics, etc.) where these concepts are categorized and so that when I search for similarity of ASP and PHP, for example, it can say that they have similarity and belong into one group(or category). I hope I described my problem clearly, but if something wrong explained would be happy for your corrections. Thanks

    Read the article

  • Computation overhead in C# - Using getters/setters vs. modifying arrays directly and casting speeds

    - by Jeffrey Kern
    I was going to write a long-winded post, but I'll boil it down here: I'm trying to emulate the graphical old-school style of the NES via XNA. However, my FPS is SLOW, trying to modify 65K pixels per frame. If I just loop through all 65K pixels and set them to some arbitrary color, I get 64FPS. The code I made to look-up what colors should be placed where, I get 1FPS. I think it is because of my object-orented code. Right now, I have things divided into about six classes, with getters/setters. I'm guessing that I'm at least calling 360K getters per frame, which I think is a lot of overhead. Each class contains either/and-or 1D or 2D arrays containing custom enumerations, int, Color, or Vector2D, bytes. What if I combined all of the classes into just one, and accessed the contents of each array directly? The code would look a mess, and ditch the concepts of object-oriented coding, but the speed might be much faster. I'm also not concerned about access violations, as any attempts to get/set the data in the arrays will done in blocks. E.g., all writing to arrays will take place before any data is accessed from them. As for casting, I stated that I'm using custom enumerations, int, Color, and Vector2D, bytes. Which data types are fastest to use and access in the .net Framework, XNA, XBox, C#? I think that constant casting might be a cause of slowdown here. Also, instead of using math to figure out which indexes data should be placed in, I've used precomputed lookup tables so I don't have to use constant multiplication, addition, subtraction, division per frame. :)

    Read the article

  • Oddities in Linq-to-SQL generated code related to property change/changing events

    - by Lasse V. Karlsen
    I'm working on creating my own Linq-to-Sql generated classes in order to learn the concepts behind it all. I have some questions, if anyone knows the answer to one or more of these I'd be much obliged. The code below, and thus the questions, are from looking at code generated by creating a .DBML file in the Visual Studio 2010 designer, and inspecting the .Designer.cs file afterwards. 1. Why is INotifyPropertyChanging not passing the property name The event raising method is defined like this: protected virtual void SendPropertyChanging() Why isn't the name of the property that is changing passed to the event here? It is defined to be part of the EventArgs descendant that is passed to the event handler, but the method only passes an empty such value to it. 2. Why are the EntitySet<X> attach/detach methods not raising property changed? For an EntitySet<X> reference, the following two methods are generated: private void attach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = this; } private void detach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = null; } Why isn't SendPropertyChanged also called here? I'm sure I have more questions later, but for now these will suffice :)

    Read the article

  • python list Index out of range error

    - by dman762000
    I am working on a python tetris game that my proffessor assigned for the final project of a concepts of programming class. I have got just about everything he wanted to work on it at this point but I am having a slight problem with one part of it. Whenever I start moving pieces left and right I keep getting "index out of range error". This only happens when it is up against a piece. Here are the culprits that are giving me grief. def clearRight(block=None): global board, activeBlock, stackedBlocks isClear = True if(block == None): block = activeBlock if(block != None): for square in block['squares']: row = square[1] col = square[0]+1 if(col >= 0 and stackedBlocks[row][col] !=None): isClear=False return isClear def clearLeft(block=None): global board, activeBlock, stackedBlocks isClear = True if(block == None): block = activeBlock if(block != None): for square in block['squares']: row = square[1] col = square[0]-1 if(col >= 0 and stackedBlocks[row][col] !=None): isClear=False return isClear I am not looking to get anyone to fix it for me, I'm only looking for tips on how to fix it myself. Thanks in advance for any help that is given.

    Read the article

  • Should I put actors in the Domain-Model/Class-Diagram?

    - by devoured elysium
    When designing both the domain-model and class-diagrams I am having some trouble understanding what to put in them. I'll give an example of what I mean: I am doing a vacations scheduler program, that has an Administrator and End-Users. The Administrator does a couple of things like registering End-Users in the program, changing their previleges, etc. The End-User can choose his vacations days, etc. I initially defined an Administrator and End-User as concepts in the domain-model, and later as classes in the class-diagram. In the class-diagram, both classes ended up having a couple of methods like Administrator.RegisterNewUser(); Administrator.UnregisterUser(int id); etc. Only after some time I realised that actually both Administrator and End-User are actors, and maybe I got this design totally wrong. Instead of filling Administrator and End-User classes with methods to do what my Use-Cases request, I could define other classes from the domain to do them, and have controllers handle the Use-Cases(actually, I decided to do one for each Use-Case). I could have a UserDatabase.RegisterNewUser() and UserDatabase.UnregisterUser(int id);, for example, instead of having those methods on the Administrator class. The idea would be to try to think of the whole vacation-scheduler as a "closed-program" that has a set of features and doesn't bother with things such as authentication, that should be internal/protected, being that the only public things I'd let the outside world see would be its controllers. Is this the right approach? Or am I getting this totally wrong? Is it generally bad idea to put Actors in the domain-model/class-diagrams? What are good rules of thumb for this? My lecturer is following Applying UML and Patterns, which I find awful, so I'd like to know where I could look up more info on this described actor-models situation. I'm still a bit confused about all of this, as this new approach is radically different from anything I've done before.

    Read the article

  • static initialization confusion

    - by Happy Mittal
    I am getting very confused in some concepts in c++. For ex: I have following two files //file1.cpp class test { static int s; public: test(){s++;} }; static test t; int test::s=5; //file2.cpp #include<iostream> using namespace std; class test { static int s; public: test(){s++;} static int get() { return s; } }; static test t; int main() { cout<<test::get()<<endl; } Now My question is : 1. How two files link successfully even if they have different class definitions? 2. Are the static member s of two classes related because I get output as 7. Please explain this concept of statics.

    Read the article

  • How do software events work internally?

    - by Duddle
    Hello! I am a student of Computer Science and have learned many of the basic concepts of what is going on "under the hood" while a computer program is running. But recently I realized that I do not understand how software events work efficiently. In hardware, this is easy: instead of the processor "busy waiting" to see if something happened, the component sends an interrupt request. But how does this work in, for example, a mouse-over event? My guess is as follows: if the mouse sends a signal ("moved"), the operating system calculates its new position p, then checks what program is being drawn on the screen, tells that program position p, then the program itself checks what object is at p, checks if any event handlers are associated with said object and finally fires them. That sounds terribly inefficient to me, since a tiny mouse movement equates to a lot of cpu context switches (which I learned are relatively expensive). And then there are dozens of background applications that may want to do stuff of their own as well. Where is my intuition failing me? I realize that even "slow" 500MHz processors do 500 million operations per second, but still it seems too much work for such a simple event. Thanks in advance!

    Read the article

  • How to check Internet status in iPhone

    - by Radix
    Hello; I wanted to check whether internet is connected or not using either the SystemConfiguration or the CFNetwork i am not quite sure which one. Then i want to know that if the internet is connected then is it connected through wifi or not. I tried an example where i used the below code -(IBAction) shownetworkStatus { NSURL *url = [NSURL URLWithString:@"www.google.com"]; if (url!=NULL) { lbl.text = @"Connected"; } else { lbl.text = @"notConnected"; } } some say that its not valid as per apple and you have to use the SystemConfiguration Framework, Please let me know what needs to be done. Also i personally think that what i am doing in the above code is not proper as if one day google may also be down due to maintenance or some other factors. Also if you could provide me a link where i could display the name of the WIFI network then it would be really cool. I searched the internet then i got these Reachability.h code which again is a bouncer as i wana learn the concepts not copy paste them Thanks and Regards Radix

    Read the article

  • Identifying memory leaks in C++

    - by Dororo
    I've got the following bit of code, which I've narrowed down to be causing a memory leak (that is, in Task Manager, the Private Working Set of memory increases with the same repeated input string). I understand the concepts of heaps and stacks for memory, as well as the general rules for avoiding memory leaks, but something somewhere is still going wrong: while(!quit){ char* thebuffer = new char[210]; //checked the function, it isn't creating the leak int size = FuncToObtainInputTextFromApp(thebuffer); //stored in thebuffer string bufferstring = thebuffer; int startlog = bufferstring.find("$"); int endlog = bufferstring.find("&"); string str_text=""; str_text = bufferstring.substr(startlog,endlog-startlog+1); String^ str_text_m = gcnew String(str_text_m.c_str()); //some work done delete str_text_m; delete [] thebuffer; } The only thing I can think of is it might be the creation of 'string str_text' since it never goes out of scope since it just reloops in the while? If so, how would I resolve that? Defining it outside the while loop wouldn't solve it since it'd also remain in scope then too. Any help would be greatly appreciated.

    Read the article

  • Linux: Find all symlinks of a given 'original' file? (reverse 'readlink')

    - by sdaau
    Hi all, Consider the following command line snippet: $ cd /tmp/ $ mkdir dirA $ mkdir dirB $ echo "the contents of the 'original' file" > orig.file $ ls -la orig.file -rw-r--r-- 1 $USER $USER 36 2010-12-26 00:57 orig.file # create symlinks in dirA and dirB that point to /tmp/orig.file: $ ln -s $(pwd)/orig.file $(pwd)/dirA/ $ ln -s $(pwd)/orig.file $(pwd)/dirB/lorig.file $ ls -la dirA/ dirB/ dirA/: total 44 drwxr-xr-x 2 $USER $USER 4096 2010-12-26 00:57 . drwxrwxrwt 20 root root 36864 2010-12-26 00:57 .. lrwxrwxrwx 1 $USER $USER 14 2010-12-26 00:57 orig.file -> /tmp/orig.file dirB/: total 44 drwxr-xr-x 2 $USER $USER 4096 2010-12-26 00:58 . drwxrwxrwt 20 root root 36864 2010-12-26 00:57 .. lrwxrwxrwx 1 $USER $USER 14 2010-12-26 00:58 lorig.file -> /tmp/orig.file At this point, I can use readling to see what is the 'original' (well, I guess the usual term here is either 'target' or 'source', but those in my mind can be opposite concepts as well, so I'll just call it 'original') file of the symlinks, i.e. $ readlink -f dirA/orig.file /tmp/orig.file $ readlink -f dirB/lorig.file /tmp/orig.file ... However, what I'd like to know is - is there a command I could run on the 'original' file, and find all the symlinks that point to it? In other words, something like (pseudo): $ getsymlinks /tmp/orig.file /tmp/dirA/orig.file /tmp/dirB/lorig.file Thanks in advance for any comments, Cheers!

    Read the article

  • What are the possible tags inside the "global" tag in Magento "config.xml" file?

    - by Knowledge Craving
    Can someone professional experienced Magento developer tell me how to accomplish the following in Magento? I want to know what are the possible tags that can fit in the "global" tag of the "config.xml" page of every module's etc folder? I have tried searching for this answer at many places in Internet but in vain. Please provide the full details along with it for Magento version = 1.4.0.0, because I want at least the users accessing this website find it useful enough, instead of scratching their heads. I really want a detailed explanation, because every newbie like me gets totally confused at this point. From what I know till now, is that in this page, you can set routers, rewrites, cron jobs, admin html, front-end html and many more. But without any strong concepts, none can go ahead with the belief that his code is 100% correct w.r.t. the Magento MVC architecture. So please I want that strong fundamental concept, getting underlined here, with a detailed explanation about it, so that no one gets into this pitfall ever again. Many many thanks to those who can answer only upon knowing the total concept clearly.

    Read the article

  • Why can’t I create a database in an empty ASP MVC 2 project using Project->Add->New Item->SQL Server

    - by Dr Dork
    I'm diving head first into ASP MVC and am playing around with creating and manipulating a database. I did a search and found this tutorial for creating a database, however when I follow it, I get this error right at the start when trying to add a new database to my fresh, empty ASP MVC 2 project... A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) The only requirement the tutorial mentioned was SQL Server Express, but when I went to download it, it said it was already installed. I'm assuming it was part of the VS 2010 RC I installed and am running. So I don't know what else I need if I am missing something. This is all new to me, so I'm sure I'm missing something obvious here and after I'm done posting this question, I plan to do some more research into the topic of databases and how they work with ASP MVC. In the meantime, I was you could help me answer a couple high level questions... What am I missing/forgetting to do that is causing this error? Any suggestions for good resources/tutorials that focus on using databases with ASP MVC? I've done a lot of database programming in the past, so I'm familiar with the concepts of relational databases and the SQL language. I wish I could find a good resource for learning how to work with them in an ASP dev environment, as well as a good breakdown of all the related technologies used for working with them (i.e. LINQ to SQL). Thanks so much in advance for all your help! I'm going to start researching these questions right now.

    Read the article

  • Overlay an image over video using OpenGL ES shaders

    - by BlueVoodoo
    I am trying to understand the basic concepts of OpenGL. A week into it, I am still far from there. Once I am in glsl, I know what to do but I find getting there is the tricky bit. I am currently able to pass in video pixels which I manipulate and present. I have then been trying to add still image as an overlay. This is where I get lost. My end goal is to end up in the same fragment shader with pixel data from both my video and my still image. I imagine this means I need two textures and pass on two pixel buffers. I am currently passing the video pixels like this: glGenTextures(1, &textures[0]); //target, texture glBindTexture(GL_TEXTURE_2D, textures[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_BYTE, buffer); Would I then repeat this process on textures[1] with the second buffer from the image? If so, do I then bind both GL_TEXTURE0 and GL_TEXTURE1? ...and would my shader look something like this? uniform sampler2D videoData; uniform sampler2D imageData; once I am in the shader? It seems no matter what combination I try, image and video always ends up being just video data in both these. Sorry for the many questions merged in here, just want to clear my many assumptions and move on. To clarify the question a bit, what do I need to do to add pixels from a still image in the process described? ("easy to understand" sample code or any types of hints would be appreciated).

    Read the article

  • TCP/IP Implementation General Questions

    - by user2971023
    I've implemented the concepts shown here; http://wiki.unity3d.com/index.php/Simple_TCP/IP_Client_-_Server outside of unity and it works. (though i had to create the TCPIPServerApp from scratch as i could not find the base project anywhere). I have some general questions on how to use tcp/ip properly however. I've done some research on tcp/ip itself but I'm still a little confused. It seems like using the method above doesn't guarantee that I'll see the message (res). It just checks on every update to see if there is a different message in res. What if multiple messages are sent and the program lags or something, will i miss the earlier packet(s)? Should i instead do an array so it stores the last X messages? How do i know the data was received? Do I need to add a message id and build in my own ack into the data? Should i check to see if the port is in use before setting up a connection? Sorry for all the questions. This is all new to me but I enjoy this very much! ... Below already answered By Anton, Thanks It sounds like tcp uses its own packet numbering to ensure the packets end up in the right order on the other side. What if a packet is missed, are the subsequent packets thrown away? Or is this numbering and packet ordering, only for handling data that is broken out into multiple packets? TCP will automatically break the data into multiple packets if necessary right?

    Read the article

  • Tools for Automated Source Code Editing

    - by Steve
    I'm working on a research project to automatically modify code to include advanced mathematical concepts (like adding random effects into a loop or encapsulating an existing function with a new function that adds in a more advanced physical model). My question to the community is: are there are any good tools for manipulating source code directly? I want to do things like Swap out functions Add variable declarations wherever they are required Determine if a function is multiplied by anything Determine what functions are called on a line of code See what parameters are passed to a function and replace them with alternatives Introduce new function calls on certain lines of code Wherever possible just leaving the rest of the code untouched and write out the results I never want to actually compile the code I only want to understand what symbols are used, replace and add in a syntactically correct way, and be able to declare variables at the right position. I've been using a minimal flex/bison approach with some success but I do not feel the it is robust. I hate to take on writing a full language parser just to add some new info to the end of a line or the top of a function. It seems like this is almost what is going to be required but it also seems like there should be some tools out there to do these types of manipulations already. The code to be changed is in a variety of languages, but I'm particularly interested in FORTRAN. Any thoughts?

    Read the article

  • How is machine code understood by the machine

    - by Kraken
    I have a very naive question here, and I would like you to correct me on whatever wrong concepts I put out here. The question is as follows: I have ubuntu installed on my machine, now I write a helloWorld.c program in C language. Now, on the operating system I have a compiler installed, when I execute my helloWorld.c program, the OS schedules the compiler and that basically compiles my code into machine code, which eventually, I execute. Now my kernel code is written in C, then how does my machine interprets that code? Say my kernel code is helloWorld.c, now would not I require any compiler, to compile this code. Also, if I hardcode a compiler in maybe ROM or something, then what language is it written in? Assembly language? Let me know if I have made myself clear with the problem. Thanks. EDIT: By kernel code I mean, the code for operating system. Operating System code. I guess it is written in C right?

    Read the article

  • What goes into the "Controller" in "MVC"?

    - by P72endragon
    I think I understand the basic concepts of MVC - the Model contains the data and behaviour of the application, the View is responsible for displaying it to the user and the Controller deals with user input. What I'm uncertain about is exactly what goes in the Controller. Lets say for example I have a fairly simple application (I'm specifically thinking Java, but I suppose the same principles apply elsewhere). I organise my code into 3 packages called app.model, app.view and app.controller. Within the app.model package, I have a few classes that reflect the actual behaviour of the application. These extends Observable and use setChanged() and notifyObservers() to trigger the views to update when appropriate. The app.view package has a class (or several classes for different types of display) that uses javax.swing components to handle the display. Some of these components need to feed back into the Model. If I understand correctly, the View shouldn't have anything to do with the feedback - that should be dealt with by the Controller. So what do I actually put in the Controller? Do I put the public void actionPerformed(ActionEvent e) in the View with just a call to a method in the Controller? If so, should any validation etc be done in the Controller? If so, how do I feedback error messages back to the View - should that go through the Model again, or should the Controller just send it straight back to View? If the validation is done in the View, what do I put in the Controller? Sorry for the long question, I just wanted to document my understanding of the process and hopefully someone can clarify this issue for me!

    Read the article

  • Reality behind wireless security - the weakness of encrypting

    - by Cawas
    I welcome better key-wording here, both on tags and title, and I'll add more links as soon as possible. For some years I'm trying to conceive a wireless environment that I'd setup anywhere and advise for everyone, including from big enterprises to small home networks of 1 machine. I've always had the feeling using any kind of the so called "wireless security" methods is actually a bad design. I'm talking mostly about encrypting and pass-phrasing (which are actually two different concepts), since I won't even considering hiding SSID and mac filtering. I understand it's a natural way of thinking. With cable networking nobody can access the network unless they have access to the physical cable, so you're "secure" in the physical way. In a way, encrypting is for wireless what walling (building walls) is for the cables. And giving pass-phrases is adding a door with a key. But the cabling without encryption is also insecure. Someone just need to plugin and get your data! And while I can see the use for encrypting data, I don't think it's a security measure in wireless networks. As I said elsewhere, I believe we should encrypt only sensitive data regardless of wires. And passwords should be added to the users, always, not to wifi. For securing files, truly, best solution is backup. Sure all that doesn't happen that often, but I won't consider the most situations where people just don't care. I think there are enough situations where people actually care on using passwords on their OS users, so let's go with that in mind. For being able to break the walls or the door someone will need proper equipment such as a hammer or a master key of some kind. Same is true for breaking the wireless walls in the analogy. But, I'd say true data security is at another place. I keep promoting the Fonera concept as an instance. It opens up a free wifi port, if you choose so, and anyone can connect to the internet through that, without having any access to your LAN. It also uses a QoS which will never let your bandwidth drop from that public usage. That's security, and it's open. And who doesn't want to be able to use internet freely anywhere you can find wifi spots? I have 3G myself, but that's beyond the point here. If I have a wifi at home I want to let people freely use it for internet as to not be an hypocrite and even guests can easily access my files, just for reading access, so I don't need to keep setting up encryption and pass-phrases that are not whole compatible. I'll probably be bashed for promoting the non-usage of WPA 2 with AES or whatever, but I wanted to know from more experienced (super) users out there: what do you think? Is there really a need for encryption to have true wireless security?

    Read the article

  • Distinction between an extranet and a DMZ

    - by Markus Yrjölä
    I've been reading about intranets, extranets, DMZs and VPNs now, and I'd need some clarifications related to extranets and DMZs. I understand that they are different types of concepts - extranet allows limited access to some intranet resources, while DMZ is a subnet that sits between the internet and intranet and hosts the external-faced services. However, I'd like to know what is their distinction in practice in a usual setup? The Wikipedia article on extranets says that extranets are similar to DMZs because they are used for the same purpose (providing access to some services/resources without exposing the whole intranet). The article also states that an extranet is a part of a VPN, and this TechNet article also states that extranet access is often implemented similarly to remote intranet access, e.g. with a VPN. The TechNet article also says that commonly the extranet is hosted inside the DMZ. This Pearson article says "Although [the DMZ] is technically located within the intranet, [it] can serve as the extranet as well". This is slightly confusing. Consider this scenario: A company has a B2C website hosted in the DMZ. The website can be accessed from anywhere, but requires user authentication. The underlying web app has its database inside the intranet and also interacts with some web services that are hosted inside the intranet (i.e. it accesses intranet resources). The way I see it, the website does effectively offer a restricted access to the intranet. But can it be considered an extranet? If we take the Wikipedia definition of an extranet literally - "An extranet is a computer network that allows controlled access from outside of an organization's intranet" - I think it can. Let's say that the above can't be considered an extranet. What if we change the scenario slightly, and say it's a B2B website, where the access is e.g. limited to connections coming from a specific business partner (by using site-to-site VPN, for example). In this case it surely is an extranet, right? If this is the case, then the difference between extranet services and any other services hosted in the DMZ is simply access restrictions?

    Read the article

  • Why is the installation of certain programs always such a pain in Linux [closed]

    - by Saif Bechan
    I am new to Linux and I am trying to set up a server. For this I sometimes to need to install special software, but the installation of this is always such a pain. For example I wanted to try the htscanner to see if it did the job for me. When i got to the page there is NO INSTALLATION guide. I had to search for the right one on google. Even on google its a pain to find the right method. Just try it - google search.After a long search and tried different things I finally found out that I had te install some more software before it will work. The website says that the version I used did not had any dependencies. Thats a lie. Release0.8.1: No dependencies registered. You do need certain things for it to work. After managing to set it up it still didn't work I can't figure out why because there is no official guide on the website. So I wanted to just uninstall it and find a better solution. Uninstalling. Uninstalling something in Linux is a real mystery how this actually works. The best answer I got is to manually look for the files and delete them. Whats up with that! There is never something said about uninstalling on the websites. Even on the website of CentOS itself it tels you how to install something like rpmforge packages (it's a miracle they tell you and not have to google it) but there is no mention of what to do when you want to uninstall. Why not? The forums you get on when trying to solve your problem are most of the time in plain text, and you have to scroll trough huge error logs before you see somethings that vaguely resembles your question if you are lucky. The Question My question is if there are any recommended websites / forums that explain the basic concepts of installing and uninstalling software on Linux. And explain other useful operations. And not Wikipedia or the first hits of Google, I have been there already. I am looking for some easy to read trough guides on these operations on Linux. I have been on a lot of websites that explain some Linux operation, but I bet its easier to get a degree in rocket science than to read trough the website and understand what they try to say.

    Read the article

  • "Hostile" network in the company - please comment on a security setup

    - by TomTom
    I have a little specific problem here that I want (need) to solve in a satisfactory way. My company has multiple (IPv4) networks that are controlled by our router sitting in the middle. Typical smaller shop setup. There is now one additional network that has an IP Range OUTSIDE of our control, connected to the internet with another router OUTSIDE of our control. Call it a project network that is part of another companies network and combined via VPN they set up. This means: They control the router that is used for this network and They can reconfigure things so that they can access the machines in this network. The network is physically split on our end through some VLAN capable switches as it covers three locations. At one end there is the router the other company controls. I Need / want to give the machines used in this network access to my company network. In fact, it may be good to make them part of my active directory domain. The people working on those machines are part of my company. BUT - I need to do so without compromising the security of my company network from outside influence. Any sort of router integration using the externally controlled router is out by this idea So, my idea is this: We accept the IPv4 address space and network topology in this network is not under our control. We seek alternatives to integrate those machines into our company network. The 2 concepts I came up with are: Use some sort of VPN - have the machines log into VPN. Thanks to them using modern windows, this could be transparent DirectAccess. This essentially treats the other IP space not different than any restaurant network a laptop of the company goes in. Alternatively - establish IPv6 routing to this ethernet segment. But - and this is a trick - block all IPv6 packets in the switch before they hit the third party controlled router, so that even IF they turn on IPv6 on that thing (not used now, but they could do it) they would get not a single packet. The switch can nicely do that by pulling all IPv6 traffic coming to that port into a separate VLAN (based on ethernet protocol type). Anyone sees a problem with using he switch to isolate the outer from IPv6? Any security hole? It is sad we have to treat this network as hostile - would be a lot easier - but the support personnel there is of "known dubious quality" and the legal side is clear - we can not fulfill our obligations when we integrate them into our company while they are under a jurisdiction we don't have a say in.

    Read the article

  • Mixed sessions with Classic ASP on IIS 7.5 and Windows 2008 R2 64 bit

    - by Marcin
    Recently had an issues with a server upgrade from IIS 6 on Windows 2003 to IIS 7.5 on Windows 2008 R2 64 bit. We have a number of websites running on Classic ASP. All the sites sit under a particular site, e.g. www.example.com/foo and www.example.com/foobar. On IIS 6 each site was set up as a virtual directory and things worked fine. Since moving to the new set up, a lot of websites seem to have mixed Sessions. To be clear, this is not a app pool recycling issue; rather the sessions are populated with information when the user hits the site and while browsing they get sessions from different sites. We've determined this based on - a few customers called up and reported having their shopping cart with items with names of items belonging to a different site - also our own testing showed that some queries being run would try to bring products in from a different site We've tried - disabling dynamic caching - converting each site to be a virtual application (if I understand correctly, the virtual directory/application concepts were changed/refined somewhat in IIS 7 although to be honest, I'm not clear what the difference is) - various application pool changes (using .NET 2 framework), classic and integrated modes, changing the Process model to NetworkIdentity), all to no avail. The only thing we haven't tried is changing it to run as a 32 bit application. We're not using http only cookies, so when I open up a browser and type document.cookie into the dev console in Firefox/Chrome/IE that there will be multiple ASPSESSIONID=... values whereas previously I believe there was only one. Finally, we use server side JScript for the classic ASP pages, not VBScript, so we have code similar to the below. //the user's login account as a jscript object Session("user") = { email : "[email protected]", id : 123 }; and if we execute a line of code like below: Response.Write( typeof(Session("user")) ); When things are running correctly, we get "object" - as expected. When the Session gets trashed, the output is "unknown" and we are also unable to access the fields within the JScript object (e.g. the .email or .id fields). Much appreciated if anyone can provide any pointers about how to resolve this, everything on google seems to point to different issues.

    Read the article

  • Wrapping a point-to-point link

    - by user3712955
    I'm using a pair of IP radios (non-WiFi) to bridge my office engineering LAN (172.0.0.0/8) to a lab in another building. The radios work fine, but they expose a web management interface I'd like to hide, and they also generate traffic (ARP, STP, and more) that I need to keep off my (very, very clean) LAN segments. I have some ARM-Linux boards (similar to Beagle/Panda/RasPi) running Ubuntu, and I've put one at each end of the link, between the radio and the LAN. Each of the boards has 2 wired Ethernet interfaces, eth0 and eth1. The LAN segments are connected to eth0, and the radios are connected to eth1. I'd like to accomplish the following: Keep radio-originated traffic off my LAN segments! Hide all services provided by the radio (web, ssh, etc.) Transparently pass all traffic between the LAN segments (including things like ARP). The above also applies to the ARM-Linux boards: No stray traffic my LAN from them either! I'd like the system to look like a switch: LAN packets arriving at one eth0 appear at the other. And neither eth0 should have an IP address: The working system should behave like a CAT6 cable with some latency (instead of ARM boards and radios). Unfortunately, I'm confused about how to properly configure the ARM Ubuntu systems. What I'm guessing I need is a bridge on each board (br0?) and a VLAN (vlan0 or eth0.0?) to isolate the LAN traffic from everything else as it passes through the ARM boards and the radios. Then I need some kind of a firewall to block sending anything out eth0 that isn't from the other eth0 (via the VLAN). I've looked at the ip and ebtables commands (especially -t broute). While the concepts sorta-kinda make sense, I'm completely lost in the details. Edit: In the perverse case that a system on one of my LAN segments has the same IP address as one of the radios, or as eth1 on the ARM-Ubuntu boards, a VLAN won't work. Which I believe means I need to tunnel all traffic between the two eth0 interfaces to get that "like a wire" behavior. Help? Finally, I'd like to have a way to temporarily expose services on the ARM boards (ssh) and the radios (web) for maintenance purposes. Ideally, it would expose an IP address with ssh available on port 22. Once connected, I figure I'd start an X11 session and run a browser on the ARM board to access the radios. Or something. I could login via the console to enable/disable this, or perhaps could use a GPIO to trigger a script. I feel I've identified most of the pieces needed to make all this happen, but I have no idea how to combine them to make a working system. Thanks!

    Read the article

  • SQL SERVER – 2008 – Introduction to Snapshot Database – Restore From Snapshot

    - by pinaldave
    Snapshot database is one of the most interesting concepts that I have used at some places recently. Here is a quick definition of the subject from Book On Line: A Database Snapshot is a read-only, static view of a database (the source database). Multiple snapshots can exist on a source database and can always reside on the same server instance as the database. Each database snapshot is consistent, in terms of transactions, with the source database as of the moment of the snapshot’s creation. A snapshot persists until it is explicitly dropped by the database owner. If you do not know how Snapshot database work, here is a quick note on the subject. However, please refer to the official description on Book-on-Line for accuracy. Snapshot database is a read-only database created from an original database called the “source database”. This database operates at page level. When Snapshot database is created, it is produced on sparse files; in fact, it does not occupy any space (or occupies very little space) in the Operating System. When any data page is modified in the source database, that data page is copied to Snapshot database, making the sparse file size increases. When an unmodified data page is read in the Snapshot database, it actually reads the pages of the original database. In other words, the changes that happen in the source database are reflected in the Snapshot database. Let us see a simple example of Snapshot. In the following exercise, we will do a few operations. Please note that this script is for demo purposes only- there are a few considerations of CPU, DISK I/O and memory, which will be discussed in the future posts. Create Snapshot Delete Data from Original DB Restore Data from Snapshot First, let us create the first Snapshot database and observe the sparse file details. USE master GO -- Create Regular Database CREATE DATABASE RegularDB GO USE RegularDB GO -- Populate Regular Database with Sample Table CREATE TABLE FirstTable (ID INT, Value VARCHAR(10)) INSERT INTO FirstTable VALUES(1, 'First'); INSERT INTO FirstTable VALUES(2, 'Second'); INSERT INTO FirstTable VALUES(3, 'Third'); GO -- Create Snapshot Database CREATE DATABASE SnapshotDB ON (Name ='RegularDB', FileName='c:\SSDB.ss1') AS SNAPSHOT OF RegularDB; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO Now let us see the resultset for the same. Now let us do delete something from the Original DB and check the same details we checked before. -- Delete from Regular Database DELETE FROM RegularDB.dbo.FirstTable; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO When we check the details of sparse file created by Snapshot database, we will find some interesting details. The details of Regular DB remain the same. It clearly shows that when we delete data from Regular/Source DB, it copies the data pages to Snapshot database. This is the reason why the size of the snapshot DB is increased. Now let us take this small exercise to  the next level and restore our deleted data from Snapshot DB to Original Source DB. -- Restore Data from Snapshot Database USE master GO RESTORE DATABASE RegularDB FROM DATABASE_SNAPSHOT = 'SnapshotDB'; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Clean up DROP DATABASE [SnapshotDB]; DROP DATABASE [RegularDB]; GO Now let us check the details of the select statement and we can see that we are successful able to restore the database from Snapshot Database. We can clearly see that this is a very useful feature in case you would encounter a good business that needs it. I would like to request the readers to suggest more details if they are using this feature in their business. Also, let me know if you think it can be potentially used to achieve any tasks. Complete Script of the afore- mentioned operation for easy reference is as follows: USE master GO -- Create Regular Database CREATE DATABASE RegularDB GO USE RegularDB GO -- Populate Regular Database with Sample Table CREATE TABLE FirstTable (ID INT, Value VARCHAR(10)) INSERT INTO FirstTable VALUES(1, 'First'); INSERT INTO FirstTable VALUES(2, 'Second'); INSERT INTO FirstTable VALUES(3, 'Third'); GO -- Create Snapshot Database CREATE DATABASE SnapshotDB ON (Name ='RegularDB', FileName='c:\SSDB.ss1') AS SNAPSHOT OF RegularDB; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Delete from Regular Database DELETE FROM RegularDB.dbo.FirstTable; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Restore Data from Snapshot Database USE master GO RESTORE DATABASE RegularDB FROM DATABASE_SNAPSHOT = 'SnapshotDB'; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Clean up DROP DATABASE [SnapshotDB]; DROP DATABASE [RegularDB]; GO Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

    Read the article

  • MVC Portable Areas Enhancement &ndash; Embedded Resource Controller

    - by Steve Michelotti
    MvcContrib contains a feature called Portable Areas which I’ve recently blogged about. In short, portable areas provide a way to distribute MVC binary components as simple .NET assemblies where the aspx/ascx files are actually compiled into the assembly as embedded resources. This is an extremely cool feature but once you start building robust portable areas, you’ll also want to be able to access other external files like css and javascript.  After my recent post suggesting portable areas be expanded to include other embedded resources, Eric Hexter asked me if I’d like to contribute the code to MvcContrib (which of course I did!). Embedded resources are stored in a case-sensitive way in .NET assemblies and the existing embedded view engine inside MvcContrib already took this into account. Obviously, we’d want the same case sensitivity handling to be taken into account for any embedded resource so my job consisted of 1) adding the Embedded Resource Controller, and 2) a little refactor to extract the logic that deals with embedded resources so that the embedded view engine and the embedded resource controller could both leverage it and, therefore, keep the code DRY. The embedded resource controller targets these scenarios: External image files that are referenced in an <img> tag External files referenced like css or JavaScript files Image files referenced inside css files Embedded Resources Walkthrough This post will describe a walkthrough of using the embedded resource controller in your portable areas to include the scenarios outlined above. I will build a trivial “Quick Links” widget to illustrate the concepts. The portable area registration is the starting point for all portable areas. The MvcContrib.PortableAreas.EmbeddedResourceController is optional functionality – you must opt-in if you want to use it.  To do this, you simply “register” it by providing a route in your area registration that uses it like this: 1: context.MapRoute("ResourceRoute", "quicklinks/resource/{resourceName}", 2: new { controller = "EmbeddedResource", action = "Index" }, 3: new string[] { "MvcContrib.PortableAreas" }); First, notice that I can specify any route I want (e.g., “quicklinks/resources/…”).  Second, notice that I need to include the “MvcContrib.PortableAreas” namespace as the fourth parameter so that the framework is able to find the EmbeddedResourceController at runtime. The handling of embedded views and embedded resources have now been merged.  Therefore, the call to: 1: RegisterTheViewsInTheEmmeddedViewEngine(GetType()); has now been removed (breaking change).  It has been replaced with: 1: RegisterAreaEmbeddedResources(); Other than that, the portable area registration remains unchanged. The solution structure for the static files in my portable area looks like this: I’ve got a css file in a folder called “Content” as well as a couple of image files in a folder called “images”. To reference these in my aspx/ascx code, all of have to do is this: 1: <link href="<%= Url.Resource("Content.QuickLinks.css") %>" rel="stylesheet" type="text/css" /> 2: <img src="<%= Url.Resource("images.globe.png") %>" /> This results in the following HTML mark up: 1: <link href="/quicklinks/resource/Content.QuickLinks.css" rel="stylesheet" type="text/css" /> 2: <img src="/quicklinks/resource/images.globe.png" /> The Url.Resource() method is now included in MvcContrib as well. Make sure you import the “MvcContrib” namespace in your views. Next, I have to following html to render the quick links: 1: <ul class="links"> 2: <li><a href="http://www.google.com">Google</a></li> 3: <li><a href="http://www.bing.com">Bing</a></li> 4: <li><a href="http://www.yahoo.com">Yahoo</a></li> 5: </ul> Notice the <ul> tag has a class called “links”. This is defined inside my QuickLinks.css file and looks like this: 1: ul.links li 2: { 3: background: url(/quicklinks/resource/images.navigation.png) left 4px no-repeat; 4: padding-left: 20px; 5: margin-bottom: 4px; 6: } On line 3 we’re able to refer to the url for the background property. As a final note, although we already have complete control over the location of the embedded resources inside the assembly, what if we also want control over the physical URL routes as well. This point was raised by John Nelson in this post. This has been taken into account as well. For example, suppose you want your physical url to look like this: 1: <img src="/quicklinks/images/globe.png" /> instead of the same corresponding URL shown above (i.e., “/quicklinks/resources/images.globe.png”). You can do this easily by specifying another route for it which includes a “resourcePath” parameter that is pre-pended. Here is the complete code for the area registration with the custom route for the images shown on lines 9-11: 1: public class QuickLinksRegistration : PortableAreaRegistration 2: { 3: public override void RegisterArea(System.Web.Mvc.AreaRegistrationContext context, IApplicationBus bus) 4: { 5: context.MapRoute("ResourceRoute", "quicklinks/resource/{resourceName}", 6: new { controller = "EmbeddedResource", action = "Index" }, 7: new string[] { "MvcContrib.PortableAreas" }); 8:   9: context.MapRoute("ResourceImageRoute", "quicklinks/images/{resourceName}", 10: new { controller = "EmbeddedResource", action = "Index", resourcePath = "images" }, 11: new string[] { "MvcContrib.PortableAreas" }); 12:   13: context.MapRoute("quicklink", "quicklinks/{controller}/{action}", 14: new {controller = "links", action = "index"}); 15:   16: this.RegisterAreaEmbeddedResources(); 17: } 18:   19: public override string AreaName 20: { 21: get 22: { 23: return "QuickLinks"; 24: } 25: } 26: } The Quick Links portable area results in the following requests (including custom route formats): The complete code for this post is now included in the Portable Areas sample solution in the latest MvcContrib source code. You can get the latest code now.  Portable Areas open up exciting new possibilities for MVC development!

    Read the article

< Previous Page | 57 58 59 60 61 62 63 64 65 66 67 68  | Next Page >