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  • Call methods in main method

    - by Niloo
    this is my main method that gets 3 integers from command line and I parse then in my validating method. However I have one operation method that calls 3 other methods, but i don't know what type of data and howmany I have to put in my operatinMethod() " cuase switch only gets one); AND also in my mainMethod() for calling the operationMehod(); itself? please let me know if i'm not clear? Thanx! main method: public class test { // Global Constants final static int MIN_NUMBER = 1; final static int MAX_PRIME = 10000; final static int MAX_FACTORIAL = 12; final static int MAX_LEAPYEAR = 4000; //Global Variables static int a,b,c; public static void main (String[] args) { for(int i =0; i< args.length; i++){} if(validateInput(args[0],args[1],args[2])){ performOperations(); } } //Validate User Input public static boolean validateInput(String num1,String num2,String num3){ boolean isValid = false; try{ try{ try{ a = Integer.parseInt(num1); if(!withinRange(a,MIN_NUMBER, MAX_PRIME)) { System.out.println("The entered value " + num1 +" is out of range [1 TO 10000]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num1 + " is not a valid integer. Please try again."); } b = Integer.parseInt(num2); if(!withinRange(b,MIN_NUMBER, MAX_FACTORIAL)) { System.out.println("The entered value " + num2 +" is out of range [1 TO 12]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num2 + " is not a valid integer. Please try again."); } c = Integer.parseInt(num3); if(!withinRange(c,MIN_NUMBER, MAX_LEAPYEAR)) { System.out.println("The entered value " + num3 +" is out of range [1 TO 4000]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num3 + " is not a valid integer. Please try again."); } return isValid; } //Check the value within the specified range private static boolean withinRange(int userInput ,int min, int max){ boolean isInRange = true; if(userInput < min || userInput > max){ isInRange = false; } return isInRange; } //Perform operations private static void performOperations(int userInput) { switch(userInput) { case 1: // count Prime numbers countPrimes(a); break; case 2: // Calculate factorial getFactorial(b); break; case 3: // find Leap year isLeapYear(c); break; } } // Verify Prime Number private static boolean isPrime(int prime) { for(int i = 2; i <= Math.sqrt(prime) ; i++) { if ((prime % i) == 0) { return false; } } return true; } // Calculate Prime private static int countPrimes(int userInput){ int count =0; for(int i=userInput; i<=MAX_PRIME; i++) { if(isPrime(i)){ count++; } } System.out.println("Exactly "+ count + " prime numbers exist between "+ a + " and 10,000."); return count; } // Calculate the factorial value private static int getFactorial(int userInput){ int ans = userInput; if(userInput >1 ){ ans*= (getFactorial(userInput-1)); //System.out.println("The value of "+ b +"! is "+ getFactorial(userInput)); } return ans; } // Determine whether the integer represents a leap year private static boolean isLeapYear(int userInput){ if (userInput % 4 == 0 && userInput % 400 == 0 && userInput % 100 ==0){ System.out.println("The year "+ c +" is a leap year"); } else { System.out.println("The year "+ c +" is a not leap year"); } return false; } }

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  • How to be sure that my MVC project is runting on the correct version after upgrade to vs2010?

    - by Stephane
    I just installed visual studio 2010 and upgraded my MVC project (which was running on MVC RC2 in visual studio 2008). visual studio 2010 updated every project file to target the framework 4.0. But the system.web.dll is pointing to C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 2\Assemblies\System.Web.Mvc.dll in VS2010 object browser, I have every dll showing up in multiple versions as expected (3.5.0.0 and 4.0.0.0) except for the System.Web.Mvc dll which doesn't show any version and points to the path I mentioned above. Isn't this namespace point to the Framework folder like the System.Web namespace? C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.dll

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  • Describe the Damas-Milner type inference in a way that a CS101 student can understand

    - by user128807
    Hindley-Milner is a type system that is the basis of the type systems of many well known functional programming languages. Damas-Milner is an algorithm that infers (deduces?) types in a Hindley-Milner type system. Wikipedia gives a description of the algorithm which, as far as I can tell, amounts to a single word: "unification." Is that all there is to it? If so, that means that the interesting part is the type system itself not the type inference system. If Damas-Milner is more than unification, I would like a description of Damas-Milner that includes a simple example and, ideally, some code. Also, this algorithm is often said to do type inference. Is it really an inference system? I thought it was only deducing the types. Related questions: What is Hindley Miller? Type inference to unification problem

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  • Is wordpress a good platform for webapp development?

    - by darlinton
    I am planning a webapp to control bank paying orders. In a quick review, the user goes online and creates a payment order. This order goes to other people that pays it and register the payment on the system. The system keeps track of all the payments, keeping the account balance up-to-date. The system needs a login system, bank integration, and to support at some point thousands of clients. We can find articles on the web about the benefits of using wordpress platform to build webapps. However, I could not find discussion with counterarguments to user wordpress. As the platform the most important choice in webapp project, I would to know more about the pitfalls and harms for choosing wordpress. The question is: What are the benefits and harms for choosing wordpress as a development platform for a webapp that need to be integrated with other system (backend systems) and to handle thousands of users (does it scale up?)?

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  • Java: how does isDirectory and isFile work in File-class?

    - by HH
    $ javac GetAllDirs.java GetAllDirs.java:16: cannot find symbol symbol : variable checkFile location: class GetAllDirs System.out.println(checkFile.getName()); ^ 1 error $ cat GetAllDirs.java import java.util.*; import java.io.*; public class GetAllDirs { public void getAllDirs(File file) { if(file.isDirectory()){ System.out.println(file.getName()); File checkFile = new File(file.getCanonicalPath()); }else if(file.isFile()){ System.out.println(file.getName()); File checkFile = new File(file.getParent()); }else{ // checkFile should get Initialized at least HERE! File checkFile = file; } System.out.println(file.getName()); // WHY ERROR HERE: checkfile not found System.out.println(checkFile.getName()); } public static void main(String[] args) { GetAllDirs dirs = new GetAllDirs(); File current = new File("."); dirs.getAllDirs(current); } }

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  • Using rvm with a standalone ruby script

    - by John Yeates
    I have rvm installed on a Mac OS X 10.6 system with the system ruby and 1.9.1. I also have this basic ruby script: #!/usr/bin/ruby require 'curb-fu' I need the script to use the system ruby regardless of what rvm's using at any given time; I'm assuming that I've got that right, at least. I've switched to the system ruby (rvm use system) and then installed the gem (gem install curb-fu). If I run irb and type require 'curb-fu', it works. However, running that script with ./myscript.rb fails: /Users/me/bin/podcast_notify.rb:6:in `require': no such file to load -- curb-fu (LoadError) from /Users/me/bin/podcast_notify.rb:6 What's going wrong here? How do I install curb-fu so that it's always available to this script?

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  • Java compiler error: "cannot find symbol" when trying to access local variable

    - by HH
    $ javac GetAllDirs.java GetAllDirs.java:16: cannot find symbol symbol : variable checkFile location: class GetAllDirs System.out.println(checkFile.getName()); ^ 1 error $ cat GetAllDirs.java import java.util.*; import java.io.*; public class GetAllDirs { public void getAllDirs(File file) { if(file.isDirectory()){ System.out.println(file.getName()); File checkFile = new File(file.getCanonicalPath()); }else if(file.isFile()){ System.out.println(file.getName()); File checkFile = new File(file.getParent()); }else{ // checkFile should get Initialized at least HERE! File checkFile = file; } System.out.println(file.getName()); // WHY ERROR HERE: checkfile not found System.out.println(checkFile.getName()); } public static void main(String[] args) { GetAllDirs dirs = new GetAllDirs(); File current = new File("."); dirs.getAllDirs(current); } }

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  • DRY and SRP

    - by Timothy Klenke
    Originally posted on: http://geekswithblogs.net/TimothyK/archive/2014/06/11/dry-and-srp.aspxKent Beck’s XP Simplicity Rules (aka Four Rules of Simple Design) are a prioritized list of rules that when applied to your code generally yield a great design.  As you’ll see from the above link the list has slightly evolved over time.  I find today they are usually listed as: All Tests Pass Don’t Repeat Yourself (DRY) Express Intent Minimalistic These are prioritized.  If your code doesn’t work (rule 1) then everything else is forfeit.  Go back to rule one and get the code working before worrying about anything else. Over the years the community have debated whether the priority of rules 2 and 3 should be reversed.  Some say a little duplication in the code is OK as long as it helps express intent.  I’ve debated it myself.  This recent post got me thinking about this again, hence this post.   I don’t think it is fair to compare “Expressing Intent” against “DRY”.  This is a comparison of apples to oranges.  “Expressing Intent” is a principal of code quality.  “Repeating Yourself” is a code smell.  A code smell is merely an indicator that there might be something wrong with the code.  It takes further investigation to determine if a violation of an underlying principal of code quality has actually occurred. For example “using nouns for method names”, “using verbs for property names”, or “using Booleans for parameters” are all code smells that indicate that code probably isn’t doing a good job at expressing intent.  They are usually very good indicators.  But what principle is the code smell of Duplication pointing to and how good of an indicator is it? Duplication in the code base is bad for a couple reasons.  If you need to make a change and that needs to be made in a number of locations it is difficult to know if you have caught all of them.  This can lead to bugs if/when one of those locations is overlooked.  By refactoring the code to remove all duplication there will be left with only one place to change, thereby eliminating this problem. With most projects the code becomes the single source of truth for a project.  If a production code base is inconsistent with a five year old requirements or design document the production code that people are currently living with is usually declared as the current reality (or truth).  Requirement or design documents at this age in a project life cycle are usually of little value. Although comparing production code to external documentation is usually straight forward, duplication within the code base muddles this declaration of truth.  When code is duplicated small discrepancies will creep in between the two copies over time.  The question then becomes which copy is correct?  As different factions debate how the software should work, trust in the software and the team behind it erodes. The code smell of Duplication points to a violation of the “Single Source of Truth” principle.  Let me define that as: A stakeholder’s requirement for a software change should never cause more than one class to change. Violation of the Single Source of Truth principle will always result in duplication in the code.  However, the inverse is not always true.  Duplication in the code does not necessarily indicate that there is a violation of the Single Source of Truth principle. To illustrate this, let’s look at a retail system where the system will (1) send a transaction to a bank and (2) print a receipt for the customer.  Although these are two separate features of the system, they are closely related.  The reason for printing the receipt is usually to provide an audit trail back to the bank transaction.  Both features use the same data:  amount charged, account number, transaction date, customer name, retail store name, and etcetera.  Because both features use much of the same data, there is likely to be a lot of duplication between them.  This duplication can be removed by making both features use the same data access layer. Then start coming the divergent requirements.  The receipt stakeholder wants a change so that the account number has the last few digits masked out to protect the customer’s privacy.  That can be solve with a small IF statement whilst still eliminating all duplication in the system.  Then the bank wants to take a picture of the customer as well as capture their signature and/or PIN number for enhanced security.  Then the receipt owner wants to pull data from a completely different system to report the customer’s loyalty program point total. After a while you realize that the two stakeholders have somewhat similar, but ultimately different responsibilities.  They have their own reasons for pulling the data access layer in different directions.  Then it dawns on you, the Single Responsibility Principle: There should never be more than one reason for a class to change. In this example we have two stakeholders giving two separate reasons for the data access class to change.  It is clear violation of the Single Responsibility Principle.  That’s a problem because it can often lead the project owner pitting the two stakeholders against each other in a vein attempt to get them to work out a mutual single source of truth.  But that doesn’t exist.  There are two completely valid truths that the developers need to support.  How is this to be supported and honour the Single Responsibility Principle?  The solution is to duplicate the data access layer and let each stakeholder control their own copy. The Single Source of Truth and Single Responsibility Principles are very closely related.  SST tells you when to remove duplication; SRP tells you when to introduce it.  They may seem to be fighting each other, but really they are not.  The key is to clearly identify the different responsibilities (or sources of truth) over a system.  Sometimes there is a single person with that responsibility, other times there are many.  This can be especially difficult if the same person has dual responsibilities.  They might not even realize they are wearing multiple hats. In my opinion Single Source of Truth should be listed as the second rule of simple design with Express Intent at number three.  Investigation of the DRY code smell should yield to the proper application SST, without violating SRP.  When necessary leave duplication in the system and let the class names express the different people that are responsible for controlling them.  Knowing all the people with responsibilities over a system is the higher priority because you’ll need to know this before you can express it.  Although it may be a code smell when there is duplication in the code, it does not necessarily mean that the coder has chosen to be expressive over DRY or that the code is bad.

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  • how to create a watcher using fsevents in mac osx 10.6

    - by mathan
    I m trying to get file event notifications using fsevents.h file. I m working with Mac OS X 10.6 and XCode 3.1.4 in which i found fsevents.h in four following locations /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/Versions/A/Headers/FSEvents.h /Xcode3.1.4/SDKs/MacOSX10.5.sdk/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/Versions/A/Headers /Developer/SDKs/MacOSX10.5.sdk/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/Versions/A/Headers /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/Versions/A/Headers I have following issues in accessing fsevents.h 1) Out of above four locations which one should be included since fsevents is not getting included unless i put following include syntax include<../../../../Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/Versions/A/Headers/fsevents.h 2) Where could I find the function definition whose prototypes are declared in fsevents.h using "extern" keyword

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  • How to improve my LDAP schema?

    - by asmaier
    Hello, I have a OpenLDAP Database and it holds some project objects that look like dn: cn=Proj1,ou=Project,ou=ua,dc=org cn: Proj1 objectClass: top objectClass: posixGroup member: 001ag member: 002ag System: ABEL System: PCx Budget: ABEL:1000000:0.3 Budget: PCx:300000:0.3 One can see that the Budget attribute is a ":"-separated string, where the first part holds the name of the system the budget is for, the second part holds some budget (which may change every month) and the last entry is a conversion factor for the budget of that system. Seeing this, I thought this is bad database design, since attribute values should always be atomic. But how can I improve that in LDAP, so that I can do a direct ldapsearch or a direct ldapmodify of the budget of System "ABEL" instead of writing a script, that will have to parse and split the ":"-separated string?

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  • Users being forced to re-login randomly, before session and auth ticket timeout values are reached

    - by Don
    I'm having reports and complaints from my user that they will be using a screen and get kicked back to the login screen immediately on their next request. It doesn't happen all the time but randomly. After looking at the Web server the error that shows up in the application event log is: Event code: 4005 Event message: Forms authentication failed for the request. Reason: The ticket supplied has expired. Everything that I read starts out with people asking about web gardens or load balancing. We are not using either of those. We're a single Windows 2003 (32-bit OS, 64-bit hardware) Server with IIS6. This is the only website on this server too. This behavior does not generate any application exceptions or visible issues to the user. They just get booted back to the login screen and are forced to login. As you can imagine this is extremely annoying and counter-productive for our users. Here's what I have set in my web.config for the application in the root: <authentication mode="Forms"> <forms name=".TcaNet" protection="All" timeout="40" loginUrl="~/Login.aspx" defaultUrl="~/MyHome.aspx" path="/" slidingExpiration="true" requireSSL="false" /> </authentication> I have also read that if you have some locations setup that no longer exist or are bogus you could have issues. My path attributes are all valid directories so that shouldn't be the problem: <location path="js"> <system.web> <authorization> <allow users="*" /> </authorization> </system.web> </location> <location path="images"> <system.web> <authorization> <allow users="*" /> </authorization> </system.web> </location> <location path="anon"> <system.web> <authorization> <allow users="*" /> </authorization> </system.web> </location> <location path="App_Themes"> <system.web> <authorization> <allow users="*" /> </authorization> </system.web> </location> <location path="NonSSL"> <system.web> <authorization> <allow users="*" /> </authorization> </system.web> </location> The only thing I'm not clear on is if my timeout value in the forms property for the auth ticket has to be the same as my session timeout value (defined in the app's configuration in IIS). I've read some things that say you should have the authentication timeout shorter (40) than the session timeout (45) to avoid possible complications. Either way we have users that get kicked to the login screen a minute or two after their last action. So the session definitely should not be expiring. Update 2/23/09: I've since set the session timeout and authentication ticket timeout values to both be 45 and the problem still seems to be happening. The only other web.config in the application is in 1 virtual directory that hosts Community Server. That web.config's authentication settings are as follows: <authentication mode="Forms"> <forms name=".TcaNet" protection="All" timeout="40" loginUrl="~/Login.aspx" defaultUrl="~/MyHome.aspx" path="/" slidingExpiration="true" requireSSL="true" /> </authentication> And while I don't believe it applies unless you're in a web garden, I have both of the machine key values set in both web.config files to be the same (removed for convenience): <machineKey validationKey="<MYVALIDATIONKEYHERE>" decryptionKey="<MYDECRYPTIONKEYHERE>" validation="SHA1" /> <machineKey validationKey="<MYVALIDATIONKEYHERE>" decryptionKey="<MYDECRYPTIONKEYHERE>" validation="SHA1"/> Any help with this would be greatly appreciated. This seems to be one of those problems that yields a ton of Google results, none of which seem to be fitting into my situation so far.

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  • How to be sure that my MVC project is running on the correct version after upgrade to vs2010?

    - by Stephane
    I just installed visual studio 2010 and upgraded my MVC project (which was running on MVC RC2 in visual studio 2008). visual studio 2010 updated every project file to target the framework 4.0. But the system.web.dll is pointing to C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 2\Assemblies\System.Web.Mvc.dll in VS2010 object browser, I have every dll showing up in multiple versions as expected (3.5.0.0 and 4.0.0.0) except for the System.Web.Mvc dll which doesn't show any version and points to the path I mentioned above. Isn't this namespace point to the Framework folder like the System.Web namespace? C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.dll

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  • Invalid character in a Base-64 string

    - by swetha
    I am getting this error when I am validating the user with sql membership provider this.provider.ValidateUser(userName, password); the password i have used is "freetrial". I tried trimming the spaces but still no luck!!! and the call stack is as follows: [FormatException: Invalid character in a Base-64 string.] System.Convert.FromBase64String(String s) +0 System.Web.Security.MembershipProvider.EncodePassword(String pass, Int32 passwordFormat, String salt) +54 System.Web.Security.SqlMembershipProvider.CheckPassword(String username, String password, Boolean updateLastLoginActivityDate, Boolean failIfNotApproved, String& salt, Int32& passwordFormat) +169 System.Web.Security.SqlMembershipProvider.CheckPassword(String username, String password, Boolean updateLastLoginActivityDate, Boolean failIfNotApproved) +42 System.Web.Security.SqlMembershipProvider.ValidateUser(String username, String password) +78

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  • Sharepoint Variations Error

    - by marcocampos
    I'm getting some crazy errors when trying to create variations in Sharepoint. Has anybody seen this error? PublishingPage::AttemptPairUpWithPage() Ends. this: http://wseasp05/PT/Paginas/Destaque1.aspx, destPageUrl: /ES/Paginas/Destaque1.aspx Begin DeploymentWrapper::SynchronizePeerPages(), sourcePage = Paginas/Destaque1.aspx DeploymentWrapper::SynchronizePeerPages(), synchronizeDestUrl = /ES/Paginas/Destaque1.aspx Access to the path 'C:\Windows\TEMP\11c7c12e-030d-4860-a942-f5ab71f0930d\ExportSettings.xml' is denied. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy) at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy) at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options) at System.IO.FileInfo.Create() at Microsoft.SharePoint.Deployment.Ex... ...portDataFileManager.Initialize() at Microsoft.SharePoint.Deployment.SPExport.InitializeExport() at Microsoft.SharePoint.Deployment.SPExport.Run() Export Completed. DeploymentWrapper.SynchronizePeerPages() catches UnauthorizedAccessException. Spawn failed for /ES/Paginas/Destaque1.aspx End of DeploymentWrapper.SynchronizePeerPages() Thanks in advance.

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  • Security exception with ASP.NET AJAX toolkit

    - by Rod
    I've got an ASP.NET WebForms app that I've written, which uses the ASP.NET AJAX Toolkit. I've put the MultiView control onto the web form, and it worked fine, when I had it under Vista. Well, I had to replace my machine (HD failed) and I went to Windows 7 Ultimate. I tried copying the ASP.NET app from the system (before it finally failed for good) and put it onto the Windows 7 machine. I can bring up the app fine, go to all pages, but the one with these controls on it. When I do I get the following error: Security Exception Description: The application attempted to perform an operation not allowed by the security policy. To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file. Exception Details: System.Security.SecurityException: Request for the permission of type 'System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. What's going on? How do I fix it?

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  • Setting the paper size

    - by rajaneesh
    Please help me how to set paper size in c# code . i am using api printDocument .. my code is ppvw = new PrintPreviewDialog(); ppvw.Document = printDoc; ppvw.PrintPreviewControl.StartPage = 0; ppvw.PrintPreviewControl.Zoom = 1.0; ppvw.PrintPreviewControl.Columns = 10; // Showing the Print Preview Page printDoc.BeginPrint += new System.Drawing.Printing.PrintEventHandler(PrintDoc_BeginPrint); printDoc.PrintPage += new System.Drawing.Printing.PrintPageEventHandler(PrintDoc_PrintPage); if (ppvw.ShowDialog() != DialogResult.OK) { printDoc.BeginPrint -= new System.Drawing.Printing.PrintEventHandler(PrintDoc_BeginPrint); printDoc.PrintPage -= new System.Drawing.Printing.PrintPageEventHandler(PrintDoc_PrintPage); } printDoc.PrinterSettings.DefaultPageSettings.PaperSize = new System.Drawing.Printing.PaperSize("a2", 5.0,5.0); printDoc.Print();

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  • Computer Networks UNISA - Chap 15 &ndash; Network Management

    - by MarkPearl
    After reading this section you should be able to Understand network management and the importance of documentation, baseline measurements, policies, and regulations to assess and maintain a network’s health. Manage a network’s performance using SNMP-based network management software, system and event logs, and traffic-shaping techniques Identify the reasons for and elements of an asset managements system Plan and follow regular hardware and software maintenance routines Fundamentals of Network Management Network management refers to the assessment, monitoring, and maintenance of all aspects of a network including checking for hardware faults, ensuring high QoS, maintaining records of network assets, etc. Scope of network management differs depending on the size and requirements of the network. All sub topics of network management share the goals of enhancing the efficiency and performance while preventing costly downtime or loss. Documentation The way documentation is stored may vary, but to adequately manage a network one should at least record the following… Physical topology (types of LAN and WAN topologies – ring, star, hybrid) Access method (does it use Ethernet 802.3, token ring, etc.) Protocols Devices (Switches, routers, etc) Operating Systems Applications Configurations (What version of operating system and config files for serve / client software) Baseline Measurements A baseline is a report of the network’s current state of operation. Baseline measurements might include the utilization rate for your network backbone, number of users logged on per day, etc. Baseline measurements allow you to compare future performance increases or decreases caused by network changes or events with past network performance. Obtaining baseline measurements is the only way to know for certain whether a pattern of usage has changed, or whether a network upgrade has made a difference. There are various tools available for measuring baseline performance on a network. Policies, Procedures, and Regulations Following rules helps limit chaos, confusion, and possibly downtime. The following policies and procedures and regulations make for sound network management. Media installations and management (includes designing physical layout of cable, etc.) Network addressing policies (includes choosing and applying a an addressing scheme) Resource sharing and naming conventions (includes rules for logon ID’s) Security related policies Troubleshooting procedures Backup and disaster recovery procedures In addition to internal policies, a network manager must consider external regulatory rules. Fault and Performance Management After documenting every aspect of your network and following policies and best practices, you are ready to asses you networks status on an on going basis. This process includes both performance management and fault management. Network Management Software To accomplish both fault and performance management, organizations often use enterprise-wide network management software. There various software packages that do this, each collect data from multiple networked devices at regular intervals, in a process called polling. Each managed device runs a network management agent. So as not to affect the performance of a device while collecting information, agents do not demand significant processing resources. The definition of a managed devices and their data are collected in a MIB (Management Information Base). Agents communicate information about managed devices via any of several application layer protocols. On modern networks most agents use SNMP which is part of the TCP/IP suite and typically runs over UDP on port 161. Because of the flexibility and sophisticated network management applications are a challenge to configure and fine-tune. One needs to be careful to only collect relevant information and not cause performance issues (i.e. pinging a device every 5 seconds can be a problem with thousands of devices). MRTG (Multi Router Traffic Grapher) is a simple command line utility that uses SNMP to poll devices and collects data in a log file. MRTG can be used with Windows, UNIX and Linux. System and Event Logs Virtually every condition recognized by an operating system can be recorded. This is typically done using event logs. In Windows there is a GUI event log viewer. Similar information is recorded in UNIX and Linux in a system log. Much of the information collected in event logs and syslog files does not point to a problem, even if it is marked with a warning so it is important to filter your logs appropriately to reduce the noise. Traffic Shaping When a network must handle high volumes of network traffic, users benefit from performance management technique called traffic shaping. Traffic shaping involves manipulating certain characteristics of packets, data streams, or connections to manage the type and amount of traffic traversing a network or interface at any moment. Its goals are to assure timely delivery of the most important traffic while offering the best possible performance for all users. Several types of traffic prioritization exist including prioritizing traffic according to any of the following characteristics… Protocol IP address User group DiffServr VLAN tag in a Data Link layer frame Service or application Caching In addition to traffic shaping, a network or host might use caching to improve performance. Caching is the local storage of frequently needed files that would otherwise be obtained from an external source. By keeping files close to the requester, caching allows the user to access those files quickly. The most common type of caching is Web caching, in which Web pages are stored locally. To an ISP, caching is much more than just convenience. It prevents a significant volume of WAN traffic, thus improving performance and saving money. Asset Management Another key component in managing networks is identifying and tracking its hardware. This is called asset management. The first step to asset management is to take an inventory of each node on the network. You will also want to keep records of every piece of software purchased by your organization. Asset management simplifies maintaining and upgrading the network chiefly because you know what the system includes. In addition, asset management provides network administrators with information about the costs and benefits of certain types of hardware or software. Change Management Networks are always in a stage of flux with various aspects including… Software changes and patches Client Upgrades Shared Application Upgrades NOS Upgrades Hardware and Physical Plant Changes Cabling Upgrades Backbone Upgrades For a detailed explanation on each of these read the textbook (Page 750 – 761)

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  • Big Data – Buzz Words: What is HDFS – Day 8 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned what is MapReduce. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – HDFS. What is HDFS ? HDFS stands for Hadoop Distributed File System and it is a primary storage system used by Hadoop. It provides high performance access to data across Hadoop clusters. It is usually deployed on low-cost commodity hardware. In commodity hardware deployment server failures are very common. Due to the same reason HDFS is built to have high fault tolerance. The data transfer rate between compute nodes in HDFS is very high, which leads to reduced risk of failure. HDFS creates smaller pieces of the big data and distributes it on different nodes. It also copies each smaller piece to multiple times on different nodes. Hence when any node with the data crashes the system is automatically able to use the data from a different node and continue the process. This is the key feature of the HDFS system. Architecture of HDFS The architecture of the HDFS is master/slave architecture. An HDFS cluster always consists of single NameNode. This single NameNode is a master server and it manages the file system as well regulates access to various files. In additional to NameNode there are multiple DataNodes. There is always one DataNode for each data server. In HDFS a big file is split into one or more blocks and those blocks are stored in a set of DataNodes. The primary task of the NameNode is to open, close or rename files and directory and regulate access to the file system, whereas the primary task of the DataNode is read and write to the file systems. DataNode is also responsible for the creation, deletion or replication of the data based on the instruction from NameNode. In reality, NameNode and DataNode are software designed to run on commodity machine build in Java language. Visual Representation of HDFS Architecture Let us understand how HDFS works with the help of the diagram. Client APP or HDFS Client connects to NameSpace as well as DataNode. Client App access to the DataNode is regulated by NameSpace Node. NameSpace Node allows Client App to connect to the DataNode based by allowing the connection to the DataNode directly. A big data file is divided into multiple data blocks (let us assume that those data chunks are A,B,C and D. Client App will later on write data blocks directly to the DataNode. Client App does not have to directly write to all the node. It just has to write to any one of the node and NameNode will decide on which other DataNode it will have to replicate the data. In our example Client App directly writes to DataNode 1 and detained 3. However, data chunks are automatically replicated to other nodes. All the information like in which DataNode which data block is placed is written back to NameNode. High Availability During Disaster Now as multiple DataNode have same data blocks in the case of any DataNode which faces the disaster, the entire process will continue as other DataNode will assume the role to serve the specific data block which was on the failed node. This system provides very high tolerance to disaster and provides high availability. If you notice there is only single NameNode in our architecture. If that node fails our entire Hadoop Application will stop performing as it is a single node where we store all the metadata. As this node is very critical, it is usually replicated on another clustered as well as on another data rack. Though, that replicated node is not operational in architecture, it has all the necessary data to perform the task of the NameNode in the case of the NameNode fails. The entire Hadoop architecture is built to function smoothly even there are node failures or hardware malfunction. It is built on the simple concept that data is so big it is impossible to have come up with a single piece of the hardware which can manage it properly. We need lots of commodity (cheap) hardware to manage our big data and hardware failure is part of the commodity servers. To reduce the impact of hardware failure Hadoop architecture is built to overcome the limitation of the non-functioning hardware. Tomorrow In tomorrow’s blog post we will discuss the importance of the relational database in Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Watching a variable for changes without polling.

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

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  • Rkhunter 122 suspect files; do I have a problem?

    - by user276166
    I am new to ubuntu. I am using Xfce Ubuntu 14.04 LTS. I have ran rkhunter a few weeks age and only got a few warnings. The forum said that they were normal. But, this time rkhunter reported 122 warnings. Please advise. casey@Shaman:~$ sudo rkhunter -c [ Rootkit Hunter version 1.4.0 ] Checking system commands... Performing 'strings' command checks Checking 'strings' command [ OK ] Performing 'shared libraries' checks Checking for preloading variables [ None found ] Checking for preloaded libraries [ None found ] Checking LD_LIBRARY_PATH variable [ Not found ] Performing file properties checks Checking for prerequisites [ Warning ] /usr/sbin/adduser [ Warning ] /usr/sbin/chroot [ Warning ] /usr/sbin/cron [ OK ] /usr/sbin/groupadd [ Warning ] /usr/sbin/groupdel [ Warning ] /usr/sbin/groupmod [ Warning ] /usr/sbin/grpck [ Warning ] /usr/sbin/nologin [ Warning ] /usr/sbin/pwck [ Warning ] /usr/sbin/rsyslogd [ Warning ] /usr/sbin/useradd [ Warning ] /usr/sbin/userdel [ Warning ] /usr/sbin/usermod [ Warning ] /usr/sbin/vipw [ Warning ] /usr/bin/awk [ Warning ] /usr/bin/basename [ Warning ] /usr/bin/chattr [ Warning ] /usr/bin/cut [ Warning ] /usr/bin/diff [ Warning ] /usr/bin/dirname [ Warning ] /usr/bin/dpkg [ Warning ] /usr/bin/dpkg-query [ Warning ] /usr/bin/du [ Warning ] /usr/bin/env [ Warning ] /usr/bin/file [ Warning ] /usr/bin/find [ Warning ] /usr/bin/GET [ Warning ] /usr/bin/groups [ Warning ] /usr/bin/head [ Warning ] /usr/bin/id [ Warning ] /usr/bin/killall [ OK ] /usr/bin/last [ Warning ] /usr/bin/lastlog [ Warning ] /usr/bin/ldd [ Warning ] /usr/bin/less [ OK ] /usr/bin/locate [ OK ] /usr/bin/logger [ Warning ] /usr/bin/lsattr [ Warning ] /usr/bin/lsof [ OK ] /usr/bin/mail [ OK ] /usr/bin/md5sum [ Warning ] /usr/bin/mlocate [ OK ] /usr/bin/newgrp [ Warning ] /usr/bin/passwd [ Warning ] /usr/bin/perl [ Warning ] /usr/bin/pgrep [ Warning ] /usr/bin/pkill [ Warning ] /usr/bin/pstree [ OK ] /usr/bin/rkhunter [ OK ] /usr/bin/rpm [ Warning ] /usr/bin/runcon [ Warning ] /usr/bin/sha1sum [ Warning ] /usr/bin/sha224sum [ Warning ] /usr/bin/sha256sum [ Warning ] /usr/bin/sha384sum [ Warning ] /usr/bin/sha512sum [ Warning ] /usr/bin/size [ Warning ] /usr/bin/sort [ Warning ] /usr/bin/stat [ Warning ] /usr/bin/strace [ Warning ] /usr/bin/strings [ Warning ] /usr/bin/sudo [ Warning ] /usr/bin/tail [ Warning ] /usr/bin/test [ Warning ] /usr/bin/top [ Warning ] /usr/bin/touch [ Warning ] /usr/bin/tr [ Warning ] /usr/bin/uniq [ Warning ] /usr/bin/users [ Warning ] /usr/bin/vmstat [ Warning ] /usr/bin/w [ Warning ] /usr/bin/watch [ Warning ] /usr/bin/wc [ Warning ] /usr/bin/wget [ Warning ] /usr/bin/whatis [ Warning ] /usr/bin/whereis [ Warning ] /usr/bin/which [ OK ] /usr/bin/who [ Warning ] /usr/bin/whoami [ Warning ] /usr/bin/unhide.rb [ Warning ] /usr/bin/mawk [ Warning ] /usr/bin/lwp-request [ Warning ] /usr/bin/heirloom-mailx [ OK ] /usr/bin/w.procps [ Warning ] /sbin/depmod [ Warning ] /sbin/fsck [ Warning ] /sbin/ifconfig [ Warning ] /sbin/ifdown [ Warning ] /sbin/ifup [ Warning ] /sbin/init [ Warning ] /sbin/insmod [ Warning ] /sbin/ip [ Warning ] /sbin/lsmod [ Warning ] /sbin/modinfo [ Warning ] /sbin/modprobe [ Warning ] /sbin/rmmod [ Warning ] /sbin/route [ Warning ] /sbin/runlevel [ Warning ] /sbin/sulogin [ Warning ] /sbin/sysctl [ Warning ] /bin/bash [ Warning ] /bin/cat [ Warning ] /bin/chmod [ Warning ] /bin/chown [ Warning ] /bin/cp [ Warning ] /bin/date [ Warning ] /bin/df [ Warning ] /bin/dmesg [ Warning ] /bin/echo [ Warning ] /bin/ed [ OK ] /bin/egrep [ Warning ] /bin/fgrep [ Warning ] /bin/fuser [ OK ] /bin/grep [ Warning ] /bin/ip [ Warning ] /bin/kill [ Warning ] /bin/less [ OK ] /bin/login [ Warning ] /bin/ls [ Warning ] /bin/lsmod [ Warning ] /bin/mktemp [ Warning ] /bin/more [ Warning ] /bin/mount [ Warning ] /bin/mv [ Warning ] /bin/netstat [ Warning ] /bin/ping [ Warning ] /bin/ps [ Warning ] /bin/pwd [ Warning ] /bin/readlink [ Warning ] /bin/sed [ Warning ] /bin/sh [ Warning ] /bin/su [ Warning ] /bin/touch [ Warning ] /bin/uname [ Warning ] /bin/which [ OK ] /bin/kmod [ Warning ] /bin/dash [ Warning ] [Press <ENTER> to continue] Checking for rootkits... Performing check of known rootkit files and directories 55808 Trojan - Variant A [ Not found ] ADM Worm [ Not found ] AjaKit Rootkit [ Not found ] Adore Rootkit [ Not found ] aPa Kit [ Not found ] Apache Worm [ Not found ] Ambient (ark) Rootkit [ Not found ] Balaur Rootkit [ Not found ] BeastKit Rootkit [ Not found ] beX2 Rootkit [ Not found ] BOBKit Rootkit [ Not found ] cb Rootkit [ Not found ] CiNIK Worm (Slapper.B variant) [ Not found ] Danny-Boy's Abuse Kit [ Not found ] Devil RootKit [ Not found ] Dica-Kit Rootkit [ Not found ] Dreams Rootkit [ Not found ] Duarawkz Rootkit [ Not found ] Enye LKM [ Not found ] Flea Linux Rootkit [ Not found ] Fu Rootkit [ Not found ] Fuck`it Rootkit [ Not found ] GasKit Rootkit [ Not found ] Heroin LKM [ Not found ] HjC Kit [ Not found ] ignoKit Rootkit [ Not found ] IntoXonia-NG Rootkit [ Not found ] Irix Rootkit [ Not found ] Jynx Rootkit [ Not found ] KBeast Rootkit [ Not found ] Kitko Rootkit [ Not found ] Knark Rootkit [ Not found ] ld-linuxv.so Rootkit [ Not found ] Li0n Worm [ Not found ] Lockit / LJK2 Rootkit [ Not found ] Mood-NT Rootkit [ Not found ] MRK Rootkit [ Not found ] Ni0 Rootkit [ Not found ] Ohhara Rootkit [ Not found ] Optic Kit (Tux) Worm [ Not found ] Oz Rootkit [ Not found ] Phalanx Rootkit [ Not found ] Phalanx2 Rootkit [ Not found ] Phalanx2 Rootkit (extended tests) [ Not found ] Portacelo Rootkit [ Not found ] R3dstorm Toolkit [ Not found ] RH-Sharpe's Rootkit [ Not found ] RSHA's Rootkit [ Not found ] Scalper Worm [ Not found ] Sebek LKM [ Not found ] Shutdown Rootkit [ Not found ] SHV4 Rootkit [ Not found ] SHV5 Rootkit [ Not found ] Sin Rootkit [ Not found ] Slapper Worm [ Not found ] Sneakin Rootkit [ Not found ] 'Spanish' Rootkit [ Not found ] Suckit Rootkit [ Not found ] Superkit Rootkit [ Not found ] TBD (Telnet BackDoor) [ Not found ] TeLeKiT Rootkit [ Not found ] T0rn Rootkit [ Not found ] trNkit Rootkit [ Not found ] Trojanit Kit [ Not found ] Tuxtendo Rootkit [ Not found ] URK Rootkit [ Not found ] Vampire Rootkit [ Not found ] VcKit Rootkit [ Not found ] Volc Rootkit [ Not found ] Xzibit Rootkit [ Not found ] zaRwT.KiT Rootkit [ Not found ] ZK Rootkit [ Not found ] [Press <ENTER> to continue] Performing additional rootkit checks Suckit Rookit additional checks [ OK ] Checking for possible rootkit files and directories [ None found ] Checking for possible rootkit strings [ None found ] Performing malware checks Checking running processes for suspicious files [ None found ] Checking for login backdoors [ None found ] Checking for suspicious directories [ None found ] Checking for sniffer log files [ None found ] Performing Linux specific checks Checking loaded kernel modules [ OK ] Checking kernel module names [ OK ] [Press <ENTER> to continue] Checking the network... Performing checks on the network ports Checking for backdoor ports [ None found ] Checking for hidden ports [ Skipped ] Performing checks on the network interfaces Checking for promiscuous interfaces [ None found ] Checking the local host... Performing system boot checks Checking for local host name [ Found ] Checking for system startup files [ Found ] Checking system startup files for malware [ None found ] Performing group and account checks Checking for passwd file [ Found ] Checking for root equivalent (UID 0) accounts [ None found ] Checking for passwordless accounts [ None found ] Checking for passwd file changes [ Warning ] Checking for group file changes [ Warning ] Checking root account shell history files [ None found ] Performing system configuration file checks Checking for SSH configuration file [ Not found ] Checking for running syslog daemon [ Found ] Checking for syslog configuration file [ Found ] Checking if syslog remote logging is allowed [ Not allowed ] Performing filesystem checks Checking /dev for suspicious file types [ Warning ] Checking for hidden files and directories [ Warning ] [Press <ENTER> to continue] System checks summary ===================== File properties checks... Required commands check failed Files checked: 137 Suspect files: 122 Rootkit checks... Rootkits checked : 291 Possible rootkits: 0 Applications checks... All checks skipped The system checks took: 5 minutes and 11 seconds All results have been written to the log file (/var/log/rkhunter.log)

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  • DBA Best Practices - A Blog Series: Episode 1 - Backups

    - by Argenis
      This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups had completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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  • Iterating through tooltips

    - by icemanind
    Guys, I have a windows form with a panel control and inside the panel control are several other controls with a System.Windows.Forms.Tooltip attached to them. How can I iterate through each tooltip and set the Active property of the tooltip to false? Tooltips, unlike other controls, are not actually controls. So I had this: foreach (System.Windows.Forms.Control ctrl in this.pnlControl.Controls) { if (ctrl.Name.StartsWith("tt")) // since all my tooltip names start with 'tt' { System.Windows.Forms.ToolTip TipControl=(System.Windows.Forms.ToolTip)ctrl; TipControl.Active=false; } } This does not work though. It gets an error because the ToolTip control is not inherited from System.Windows.Forms.Control. Any ideas?

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  • DBA Best Practices - A Blog Series: Episode 1 - Backups

    - by Argenis
      This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups have completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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  • Groupby in relationtable

    - by Dofs
    I am creating some tag functionality for a forum using linq2sql, and I have two tables [Tag] TagId TagName [ForumTagRelation] TagId ForumId I would like to retrieve, like SO, the most popular tags. I have tried to do this by: List<Tag> popularTags = db.Tags.Select(x => x.ForumTagRelations.GroupBy(y => y.TagId).OrderByDescending(z => z.Count())).Take(count).ToList(); But this just returns the following error: Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<System.Linq.IOrderedEnumerable<System.Linq.IGrouping<System.Guid?,SampleWebsite.ForumTagRelation>>>' to 'System.Collections.Generic.IEnumerable<SampleWebsite.Tag>'. An explicit conversion exists (are you missing a cast?) The question is how I easily can return a list of tags which has the most counts in the ForumTagRelation table?

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  • goto statements in java

    - by user238284
    I executed the below code in Eclipse, but the GOTO statements in it is not effective. How to use it? case 2: **outsideloops:** System.out.println("Enter the marks (in 100):"); System.out.println("Subject 1:"); float sub1=Float.parseFloat(br.readLine()); **if(sub1<=101) goto outsideloops;** System.out.println("Subject 2:"); float sub2=Float.parseFloat(br.readLine()); System.out.println("Subject 3:"); float sub3=Float.parseFloat(br.readLine()); System.out.println("The Student is "+stu.average(sub1,sub2,sub3)+ "in the examinations"); break;

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