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  • Database triggers / referential integrity and in-memory caching

    - by Ran Biron
    Do you see database triggers / referential integrity rules being used in a way that changes actual data in the database (changing row w in table x causes a change in row y in table z)? If yes, How does this tie-in with the increasing popularity of in-memory caching (memcache and friends)? After all, these actions occur inside the database but the caching system must be aware of them in order to reflect to correct state (or at least invalidate the possibly changed state). I find it hard to believe that callbacks are implemented for such cases. Does anyone have real-world experience with such a setup / real-world experience with considering such a setup and abandoning it (which way did you go? if caching, how do you enforce integrity?)

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  • Java, how to trace functions called

    - by user435657
    Hi all, I want to trace the beginning [& ending] of functions called in Java, like the following code: public void foo() { System.out.println("begin of foo()"); ... System.out.println("e-n-d of foo()"); } But maintaining of the dump code System.out.println is something tedious and error-prone, for there may be tens of thounds of function in an class. Any good idea can ease this work? I don't want dump statements all over the file. Implementation of both or one of the beginning & ending traces is perferd. But, if impossible, recordings of that the function has been called is also helpful. I mean not care the exact beginnig and ending, just tell that the function has been called.

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  • VMWare additional drives...

    - by Tony
    I have a system that I imaged using VMWare Converter, and it runs perfect. However, I have a second drive on the system that I did not originally image. How can I image the second drive and add it to the virtual machine?

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  • Is it a good idea to close and open hibernate sessions frequently?

    - by Gaurav
    Hi, I'm developing an application which requires that state of entities be read from a database at frequent intervals or triggers. However, once hibernate reads the state, it doesn't re-read it unless I explicitly close the session and read the entity in a new session. Is it a good idea to open a session everytime I want to read the entity and then close it afterwards? How much of an overhead does this put on the application and the database (we use a c3p0 connection pool also)? Will it be enough to simply evict the entity from the session before reading it again?

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  • Is there anything like memcached, but for sorted lists?

    - by depesz
    I have a situation where I could really benefit from having system like memcached, but with the ability to store (per each key) sorted list of elements, and modifying the list by addition of values. For example: something.add_to_sorted_list( 'topics_list_sorted_by_title', 1234, 'some_title') something.add_to_sorted_list( 'topics_list_sorted_by_title', 5436, 'zzz') something.add_to_sorted_list( 'topics_list_sorted_by_title', 5623, 'aaa') Which I then could use like this: something.get_list_size( 'topics_list_sorted_by_title' ) // returns 3 something.get_list_elements( 'topics_list_sorted_by_title', 1, 10 ) // returns: 5623, 1234, 5436 Required system would allow me to easily get items count in every array, and fetch any number of values from the array, with the assumption that the values are sorted using attached value. I hope that the description is clear. And the question is relatively simple: is there any such system?

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  • How do I drop a foerign key in mssql?

    - by mmattax
    I have created a foreign key (in mssql / tsql) by: alter table company add CountryID varchar(3); alter table company add constraint Company_CountryID_FK foreign key(CountryID) references Country; I then run this query: alter table company drop column CountryID; and I get this error: Msg 5074, Level 16, State 4, Line 2 The object 'Company_CountryID_FK' is dependent on column 'CountryID'. Msg 4922, Level 16, State 9, Line 2 ALTER TABLE DROP COLUMN CountryID failed because one or more objects access this column. I have tried this, yet it does not seem to work: alter table company drop foreign key Company_CountryID_FK; alter table company drop column CountryID; What do I need to do to drop the CountryID column? Thanks.

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  • New harddrives failing within weeks.

    - by Jason Kealey
    I've experienced 8 hard disk failures in 3 months and have tried many things to solve the issue permanently but I have failed. I would like to know if you have any advice for me. System was running Win XP on an Asus P5W-DH Deluxe. I have setup a RAID-1 array. I started out with 2 x 500 GB 7200RPM Western Digital drives. One died. I took it out to RMA it. On the same day, the router was fried. Assumed a power surge occurred; connected an older UPS to protect the system. Once I got my hands on an identical disk, I installed it. The RAID array was rebuilt. A few days later, the other one died. Assumed the rebuild caused it to fail. Took it out for RMA. Before the other one arrived, the remaining one died. I then discovered I could re-enable them using the Intel Matrix Storage Manager. I re-enabled both and the system seemed fine for a week, until both died again. I got two new 1.5 TB 7200RPM Seagate drives and re-installed Windows 7. Also replaced the UPS and power supply. They both died again. The voltage on the plug is stable between 120 and 122V as per the UPS. None of the other devices have had any problems (monitors, etc.). At this point, I see two options: a) electrical issue in the house that was, for some reason, not blocked by the UPS. b) something else inside the system causing surges? motherboard? onboard raid controller? Failures happen fairly quickly, between 2 and 14 days after I fix the previous issue. I just gotten a new computer (Core i7) to replace it. If it is stable, I can determine that b) was the problem. If it fries its hard drive again, I can determine that it is an electrical issue in the house. Do you have any other thoughts? Any tools I can run on the drives that failed to get more information about the original SMART event history?

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  • Using charAt in java

    - by ThuL?nå F?rñ?nDö
    This is my assignment: Write a program where the user enters a string, and the program echoes it to the monitor with one character per line: C:\>java LinePerChar Enter a string: Octopus O c t o p u s I have tried, but I'm getting some compilation errors. Here's my code: import java.util.*; class CharactorEcho{ public static void main(String args []){ Scanner sc = new Scanner(System.in); System.out.println("Enter a string :"); try { String inputString = sc.nextLine(); for(int i=0; i < sc.length(); i++) { char c = inputString.charAt(i); System.out.println("" + c); } } catch(IOException e) { } } }

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  • Robust way to save/load objects with dependencies?

    - by mrteacup
    I'm writing an Android game in Java and I need a robust way to save and load application state quickly. The question seems to apply to most OO languages. To understand what I need to save: I'm using a Strategy pattern to control my game entities. The idea is I have a very general Entity class which e.g. stores the location of a bullet/player/enemy and I then attach a Behaviour class that tells the entity how to act: class Entiy { float x; float y; Behavior b; } abstract class Behavior { void update(Entity e); {} // Move about at a constant speed class MoveBehavior extends Behavior { float speed; void update ... } // Chase after another entity class ChaseBehavior extends Behavior { Entity target; void update ... } // Perform two behaviours in sequence class CombineBehavior extends Behavior { Behaviour a, b; void update ... } Essentially, Entity objects are easy to save but Behaviour objects can have a semi-complex graph of dependencies between other Entity objects and other Behaviour objects. I also have cases where a Behaviour object is shared between entities. I'm willing to change my design to make saving/loading state easier, but the above design works really well for structuring the game. Anyway, the options I've considered are: Use Java serialization. This is meant to be really slow in Android (I'll profile it sometime). I'm worried about robustness when changes are made between versions however. Use something like JSON or XML. I'm not sure how I would cope with storing the dependencies between objects however. Would I have to give each object a unique ID and then use these IDs on loading to link the right objects together? I thought I could e.g. change the ChaseBehaviour to store a ID to an entity, instead of a reference, that would be used to look up the Entity before performing the behaviour. I'd rather avoid having to write lots of loading/saving code myself as I find it really easy to make mistakes (e.g. forgetting to save something, reading things out in the wrong order). Can anyone give me any tips on good formats to save to or class designs that make saving state easier?

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  • What would be the best schema to store the 'address' for different entities?

    - by Cesar
    Suppose we're making a system where we have to store the addrees for buildings, persons, cars, etc. The address 'format' should be something like: State (From a State list) County (From a County List) Street (free text, like '5th Avenue') Number (free text, like 'Chrysler Building, Floor 10, Office No. 10') (Yes I don't live in U.S.A) What would be the best way to store that info: Should I have a Person_Address, Car_Address, ... Or the address info should be in columns on each entity, Could we have just one address table and try to link each row to a different entity? Or are there another 'better' way to handle this type of scenario? How would yo do it?

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  • Buying a new PC with fast hardware features

    - by Hooshkar
    I am web designer/developer, and I design and code "Premium Wordpress Themes" and HTML Websites. I wish to buy a new PC system with fast features, and will be installing virtual machines too. What kind of PC system would be best for a professional web designer/developer. Tell me the PC specs, e.g processor, motherboard, how much hard drive, RAM, graphic card etc. Don't really care about the price.

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  • What are your tricks for optimizing your Subversion configuration?

    - by Scott Markwell
    For a Linux or Windows system, what tricks do you do to optimize your Subversion server? The following are my current tricks for a Linux system serving over Apache with HTTPS and backed by Active Directory using LDAP authentication. Enabling KeepAlive on Apache Disable SVNPathAuthz Increase LDAP Cache Using the FSFS storage method instead of BDB Feel free to call this into question. I don't have hard proof that FSFS out performs BDB, only lots of tribal knowledge and hearsay.

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  • Use HTTP PUT to create new cache (ehCache) running on the same Tomcat?

    - by socal_javaguy
    I am trying to send a HTTP PUT (in order to create a new cache and populate it with my generated JSON) to ehCache using my webservice which is on the same local tomcat instance. Am new to RESTful Web Services and am using JDK 1.6, Tomcat 7, ehCache, and JSON. I have my POJOs defined like this: Person POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class Person { private String firstName; private String lastName; private List<House> houses; // Getters & Setters } House POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class House { private String address; private String city; private String state; // Getters & Setters } Using a PersonUtil class, I hardcoded the POJOs as follows: public class PersonUtil { public static Person getPerson() { Person person = new Person(); person.setFirstName("John"); person.setLastName("Doe"); List<House> houses = new ArrayList<House>(); House house = new House(); house.setAddress("1234 Elm Street"); house.setCity("Anytown"); house.setState("Maine"); houses.add(house); person.setHouses(houses); return person; } } Am able to create a JSON response per a GET request: @Path("") public class MyWebService{ @GET @Produces(MediaType.APPLICATION_JSON) public Person getPerson() { return PersonUtil.getPerson(); } } When deploying the war to tomcat and pointing the browser to http://localhost:8080/personservice/ Generated JSON: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So far, so good, however, I have a different app which is running on the same tomcat instance (and has support for REST): http://localhost:8080/ehcache/rest/ While tomcat is running, I can issue a PUT like this: echo "Hello World" | curl -S -T - http://localhost:8080/ehcache/rest/hello/1 When I "GET" it like this: curl http://localhost:8080/ehcache/rest/hello/1 Will yield: Hello World What I need to do is create a POST which will put my entire Person generated JSON and create a new cache: http://localhost:8080/ehcache/rest/person And when I do a "GET" on this previous URL, it should look like this: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So, far, this is what my PUT looks like: @PUT @Path("/ehcache/rest/person") @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public Response createCache() { ResponseBuilder response = Response.ok(PersonUtil.getPerson(), MediaType.APPLICATION_JSON); return response.build(); } Question(s): (1) Is this the correct way to write the PUT? (2) What should I write inside the createCache() method to have it PUT my generated JSON into: http://localhost:8080/ehcache/rest/person (3) What would the command line CURL comment look like to use the PUT? Thanks for taking the time to read this...

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  • automated GUI tests fails when running from Jenkins

    - by adm
    Jenkins(master) is installed on the Linux system and runs automated tests on the node slave (Win-XP) via ssh connection. But all the GUi tests are failed, when GUI tests are running locally(WINXP system) testst are passed. I tried tscon.exe 0 /dest:console for forwards the calls to the console but I am getting the error: Could not connect sessionID 0 to sessionname console, Error code 7045 Error [7045]:The requested session access is denied. thanks

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  • Input string was not in correct format.

    - by jawahar-sync
    Hi Experts, I had a Ribbon like custom control. I created an application using this control. These applications work fine until I change the system number format. They crashes if I change the system number format like below: Current Format = English (United State) Decimal symbol = ',' Digit group symbol = '.' When I run applications, they throw an exception "Input string not in Correct format". . Some other applications specify the Exception's message = "Input string '0,2,0,2' was not a correct format", so I think in Wpf ES's xaml files, we may declare some properties i.e Padding, Margin like "0,2,0,2" = that will cause errors with the system number format above. I have note that this error only occurs in Windows Vista, it does not occurs on Windows XP. I do not know why? I have also look at this link, But it not helps for Vista. http://support.microsoft.com/kb/968227/en-us

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  • 'Static/Constant' business ojects

    - by UpTheCreek
    I don't quite know how to ask this question, so I'll phase it as an example: Imagine in an application you have a Country object. There are two properties of this object: Name, and a 'Bordering Countries' collection. More properties might be added later, but it will be the kind of information that would change very rarely (e.g. changes of country names/borders) Lets say this application needs to know about all of the countries in the world. Where would you store these object's state? How would you new them up? It seems silly to store all this state in the DB, since it won't change very often. One option might be to have an abstract 'country' base object, and have a class for each country inheriting from this with the details of each country. But this doesn't seem quite right to me. What is the proper way of dealing with these kinds of objects?

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  • Operation Has Been Cancelled in Windows 7!!!

    - by hosseinsinohe
    Hi All I Use Windows 7.I am Not Administrator.I want run executable files in Windows ,but I can not do it,Because when I try System Has a Error: "This Operation has been cancelled due to restriction in effect on this computer.please contact your system administrator". I want Solve this problem,and I do not want contact my Administrator. I try MMC And gpedit.msc but those do not work And I See this Error Again. Please Help me

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  • ValidateRequest = False but in action it's still True and ignored that?

    - by Sadegh
    hi guy's, i want disable RequestValidation on particular view in ASP.NET MVC 2.0 RTM. so i added some necessary to view Page directive section as below: <%@ Page ValidateRequest="false" Language="C#" MasterPageFile="Path" Inherits="System.Web.Mvc.ViewPage<Path>" %> but RequestValidation isn't Disabled! i also added RequestValidation Attribute to related action in controller as below: [System.Web.Mvc.ValidateInput(false)] public System.Web.Mvc.ActionResult Create(Model instance) { //Do here something } :') but RequestValidation isn't Disabled too! in last try i set RequestValidation to false in Web.config file as below: <pages validateRequest="false" /> RequestValidation still isn't turned off! Why? thank's in advance ;)

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  • How to run a restricted set of programs with Administrator privileges without giving up Admin acces (Win7 Pro)

    - by frLich
    I have a shared system, running Windows7 X64, restricted to a 'standard user' with no password. Not everyone who has access to the system has the administrator password. This works rather well, except for some applications - specially the unlock-applications for encrypted hard drives/USB flash drives. The specific ones either require Administrator access (eg. Seagate Blackarmor) or simply fail without it -- since these programs are sending raw commands to a device, this is to be expected. I would like to be able to add the hashes of these particular programs to a whitelist, and have them run as administrator without needing any prompts. Since these are by definition on removable media, I can't simply use a filename or even a path. One of the users who shares the system can be considered 'crafty', so anything which temporarily grants administrator rights to an user account is certain to cause problems. What i'd like to be able to do: 1) Create an admin account that can only run programs from a whitelist (or, failing that, from a directory) I can't find a good way to do this: As far as I can tell, SRP applies equally to ALL users? Even if I put a "Deny" token on all directories on the system, such that new directories would inherit it, it could still potentially run things from the mounted USB devices. I also don't know whether it's possible to create a new directory that DOESN'T inherit from the parent, that would lake the deny token, and provide admin access. 2) Find a lightweight service that will run these programs in its local context Windows7 seems to block cross-privilege level communication by default, and I haven't found such for windows 7. One example seems to be "sudo" (http://pages.cpsc.ucalgary.ca/~nfriess/sudo/) but because it uses a WLNOTIFY hook, it won't work under Vista nor Windows7 Non-Solutions: - RunAs: Requires administrator password! (but everyone calls it "sudo" anyway) - RunAs /savecred: Nice idea, but appears to be completely insecure. - RUNASSPC - Same concept as RunAs, uses "encrypted" files with credentials, but checks in user-space. - Scheduled Tasks - "Fixed" permissions make this difficult, and doesn't support interactive processes even if it did. - SuRun: From Google: "Surun uses its own Windows service that adds the user to the group of administrators during program start and removes him automatically from that group again"

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  • I'm trying to implement 2 factor authentication on the cheap. How would I do that?

    - by Biff MaGriff
    Ok so I need 2 of the 3. Something the user knows. Something the user has. Something the user is. I have a system that is exposed to the internet and we need clients to connect in a secure manner to satisfy our security standards. I'm thinking when a user registers to use our system we send them an application that they install on their home system. The application generates a key based on a timed randomness algorithm. Our application server has the same algorithm so when the user submits their credentials with the key we know that they are a legitimate user. Is this a valid method of 2 factor authentication? What is another way of doing this? Are there any pitfalls that I should be aware of? Thanks for your help!

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  • Count the number of ways in which a number 'A' can be broken into a sum of 'B' numbers such that all numbers are co-prime to 'C'

    - by rajneesh2k10
    I came across the solution of a problem which involve dynamic-programming approach, solved using a three dimensional matrix. Link to actual problem is: http://community.topcoder.com/stat?c=problem_statement&pm=12189&rd=15177 Solution to this problem is here under MuddyRoad2: http://apps.topcoder.com/wiki/display/tc/SRM+555 In the last paragraph of explanation, author describes a dynamic programming approach to count the number of ways in which a number 'A' can be broken into a sum of 'B' numbers (not necessarily different), such that every number is co-prime to 3 and the order in which these numbers appear does matter. I am not able to grasp that approach. Can anyone help me understand how DP is acting here. I can't understand what is a state here and how it is derived from the previous state.

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  • making lan connection facing problem

    - by user30780
    i am making lan connection.afer all to do i have check all the setting of workgroup and all but if i am checking through ping command to check they are connected or not??only from one system reply is coming.from the secong system reply is not coming.and i m accessing the workgru=oup"the maessge\ pc2 is not accessible.the network path not found"what should i do??

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  • please give me a solution

    - by user327832
    here is the code i have written so far but ended up giving me error import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; public class Main { public static void main(String[] args) throws Exception { File file = new File("c:\\filea.txt"); InputStream is = new FileInputStream(file); long length = file.length(); System.out.println (length); bytes[] bytes = new bytes[(int) length]; try { int offset = 0; int numRead = 0; while (numRead >= 0) { numRead = is.read(bytes); } } catch (IOException e) { System.out.println ("Could not completely read file " + file.getName()); } is.close(); Object[] see = new Object[(int) length]; see[1] = bytes; System.out.println ((String[])see[1]); } }

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  • Arguments to convince to switch from CVS to SVN

    - by ereOn
    Hi, The UNIX department of my company currently uses CVS as source-version control system. They use it in a very strange way: different repositories for development/testing/production code (for the same project), no one tags anything, weird directory architecture, and so on. The system has been set for ages but now, I have an opportunity to organize a meeting where I have to suggest changes. I'd like to make them change from CVS to SVN (Mercurial or Git might be even better, however I can't really recommand using a system I don't know well, and switching to SVN will already be a great step forward). I don't have much experience with CVS so I can't compare them efficiently: I just know it doesn't support atomic operations and that it is deprecated. What killer arguments would you use to convince my collegues to do the switch ? Thank you very much.

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  • Anonymous users support vs Google bot

    - by Andy
    I have a User class in my web app that represents a user currently logged in. Every time a user vists a page, a User instance is populated based on authentication data supplied in cookies. A User instance is created even if an anonymous user logs in - and a corresponding new record is created in the User table in the database. This approach allows me to save some state info for the current user regardless of its type. The problem however with this approach is the Google bot, and other non-human web organisms crawling my pages. Every time a bot starts to walk around the site, thousands of useless records will be created in the database, each of them only to be used for a single page. Question: what is the best trade off? How to support anonymous users, save their state, and don't get too much overhead because of cookieless bots?

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