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• Update DataBase on clicking in button, after editing gridview (not automatically saving in DB, but a

  - by gaponte69

  0 vote down star I am using GridView in asp .net and editing data with edit command field property (as we know after updating the edited row, we automatically update the database), and I want to use transactions (with begin to commit statement - including rollback) to commit this update query in database, after clicking in some button (after some events for example), not automatically to insert or update the edited data from grid directly to the DB...so I want to save them somewhere temporary (even many edited rows - not just one row) and then to confirm the transaction - to update the real tables in database... Any suggestions are welcomed... I've used some good links, but very helpful, like: http://www.asp.net/learn/data-access/tutorial-63-cs.aspx http://www.asp.net/learn/data-access/tutorial-66-cs.aspx etc... etc...

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• Experiences with "language converters"?

  - by Friedrich

  I have read a few articles mentioning converters from one language to another. I'm a bit more than skeptical about the use of such kind of tools. Does anyone know or have experiences let's say about Visual Basic to Java or vs converters? Just one example to pick http://www.tvobjects.com/products/products.html, claims to be the "world leader" or so in that aspect, However if read this: http://dev.mysql.com/tech-resources/articles/active-grid.html There the author states: "The consensus of MySQL users is that automated conversion tools for MS Access do not work. For example, tools that translate existing Access applications to Java often result in 80% complete solutions where finishing the last 20% of the work takes longer than starting from scratch." Well we know we need 80% of the time to implement the first 80% functionality and another 80% of the time for the other 20 %.... So has anyone tried such tools and found them to be worthwhile?

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• Historical / auditable database

  - by Mark

  Hi all, This question is related to the schema that can be found in one of my other questions here. Basically in my database I store users, locations, sensors amongst other things. All of these things are editable in the system by users, and deletable. However - when an item is edited or deleted I need to store the old data; I need to be able to see what the data was before the change. There are also non-editable items in the database, such as "readings". They are more of a log really. Readings are logged against sensors, because its the reading for a particular sensor. If I generate a report of readings, I need to be able to see what the attributes for a location or sensor was at the time of the reading. Basically I should be able to reconstruct the data for any point in time. Now, I've done this before and got it working well by adding the following columns to each editable table: valid_from valid_to edited_by If valid_to = 9999-12-31 23:59:59 then that's the current record. If valid_to equals valid_from, then the record is deleted. However, I was never happy with the triggers I needed to use to enforce foreign key consistency. I can possibly avoid triggers by using the extension to the "PostgreSQL" database. This provides a column type called "period" which allows you to store a period of time between two dates, and then allows you to do CHECK constraints to prevent overlapping periods. That might be an answer. I am wondering though if there is another way. I've seen people mention using special historical tables, but I don't really like the thought of maintainling 2 tables for almost every 1 table (though it still might be a possibility). Maybe I could cut down my initial implementation to not bother checking the consistency of records that aren't "current" - i.e. only bother to check constraints on records where the valid_to is 9999-12-31 23:59:59. Afterall, the people who use historical tables do not seem to have constraint checks on those tables (for the same reason, you'd need triggers). Does anyone have any thoughts about this? PS - the title also mentions auditable database. In the previous system I mentioned, there is always the edited_by field. This allowed all changes to be tracked so we could always see who changed a record. Not sure how much difference that might make. Thanks.

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• INNER JOIN vs LEFT JOIN performance in SQL Server

  - by Ekkapop

  I've created SQL command that use INNER JOIN for 9 tables, anyway this command take a very long time (more than five minutes). So my folk suggest me to change INNER JOIN to LEFT JOIN because the performance of LEFT JOIN is better, at first time its despite what I know. After I changed, the speed of query is significantly improve. I want to know why LEFT JOIN is faster than INNER JOIN? My SQL command look like below: SELECT * FROM A INNER JOIN B ON ... INNER JOIN C ON ... INNER JOIN D and so no

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• How do I store keys pressed

  - by Glycerine

  I would like to store keys pressed when I listen out for the keyDown on the stage. I can add the listener fine, but I'm not getting the character I want out of the event to store it into a string. This is what I have so far: private var _addToString:String = ""; public function Hotwire() { this.addEventListener(KeyboardEvent.KEY_DOWN, keydownEventHandler); } private function keydownEventHandler(ev:KeyboardEvent):void { trace("Key pressed: " + ev.charCode ); addToString(ev.charCode); } private function addToString(value:uint):String { trace(_addToString); return _addToString += String.fromCharCode(value); } Every key I press its returns '0'. How do I convert the chatCode to a real alphanumeric character I can read later? Thanks in advance

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• How can something like BOSH be implemented using Java Servlets

  - by John

  BOSH (Bidirectional-streams Over Synchronous HTTP) is a sneaky way of implementing 2-way client-server communication in situations where true server-push is not allowed, most obviously to let a server push data to a browser client without having to use client polling. It works by the client sending a request to the server, and the server doesn't respond immediately... rather it remembers the request but only responds when it has some data to send. When this happens the client immediately sends another request so there is virtually always a 'stored request' sitting on the server ready to push data to the client. At least, that's how I think it works! My question is how you can do this using a Java EE stack i.e standard servlets. I'm rusty with them, is it allowed to send no response and cache the request somehow? If anyone could share (pseudo) code what a servlet class for handling BOSH might look like, I'd be real grateful.

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• Is there a Java equivalent to libevent?

  - by JoelPM

  I've written a high-throughput server that handles each request in its own thread. For requests coming in it is occasionally necessary to do RPCs to one or more back-ends. These back-end RPCs are handled by a separate queue and thread-pool, which provides some bounding on the number of threads created and the maximum number of connections to the back-end (it does some caching to reuse clients and save the overhead of constantly creating connections). Having done all this, though, I'm beginning to think an event-based architecture would be more efficient. In searching around I haven't found any equivalents to libevent for Java, but maybe I'm not looking in the right place? Mina-statemachine from Apache was the closest thing I found, but it looks more verbose than I need and there's no real release available. Any suggestions?

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• Is it ever a bad idea to publish a sitemap for a blog?

  - by mipadi

  I have a blog, and I have been considering publishing a sitemap for it, which would include the index page, archives page, and an entry for each individual blog post. Is this ever a bad idea? Is it a good (or useful) idea? I'm particularly interested in the <changefreq> element: I edit posts from time to time, and while that's not a common occurrence, I don't want to set a particularly infrequent change frequency that prevents search engines like Google from indexing the edits. (The sitemaps protocol says that search engines may still crawl the pages more frequently, but has no further details on the matter.)

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• Good .NET based CMS?

  - by rAm

  For many projects we had to choose a CMS platform. I came across a few CMS platforms based on .NET. I want to know your experience. Community Server (cannot be called a true CMS) DotNetNuke (DNN) Umbraco Kentico Sitefinity Can you please touch upon the following points: UI customization. Feature extension. Third party extensions Support And most important: how much time it takes to learn, as a programmer and someone who manages the application with little or no programming knowledge. Update: thanks for all the responses, I have seen the other thread but did not get a satisfactory reply addressing the Support and Time? (which I forgot to add earlier).

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• .NET TCPListener limitation ?

  - by Karnalta

  Hi all, I have a question about the usage of TCPListener in .NET... I am thinking about a client/server application and being new to this kind of application I have search a bit around the web and the solution which come the more often is to create a new thread for each new client connection. This solution seem fine but I was wondering if it was still usable with a application where you can have thousands of client at the same time ? Of course if there is thousands of client the application will not be hosted on a small desktop but on a real server, but is it the way to design an application for a large number of client ? Thank for help.

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• Preload a lot of tiny pics

  - by clorz

  I'm thinking about how to approach the problem at hand. There's a flash movie that requires a lot of relativly small images and I'm trying to optimize the time it takes for them to be preloaded. One thing I've considered it turning on KeepAlive in Apache on the server side. That works. But my mind still wonders if there's anything else ;-) So, what other approaches I may try? Is there a way to compress all those images and then unpack on client side? I have full control on both server and client side. Can even try installing something other than Apache. Cache is not an option because it already works and it's first time loading that bothers me here.

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• Linq to sql Error "Data at the root level is invalid " for nullable xml column

  - by Mukesh

  I have Created a table like CREATE TABLE [dbo].[tab1]( [Id] [int] NOT NULL, [Name] [varchar](100) NOT NULL, [Meta] [xml] NULL, CONSTRAINT [PK_tab1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] When I am doing linq to sql query to fetch a data it throw an error "data at the root level is invalid linq". In further investigation I come to know that the meta column is null in that case. In real it is nullable Do I have to remove the nullable and set some blank root node as default or there is some another way to get rid of the error. My linq Query which throws error var obj1= (from obj in dbContext.tab1s where obj.id== 123 select obj).FirstOrDefault<Tab1>();

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• Client-side Replication for SQL Server?

  - by Mighty Z

  I'd like to have some degree of fault tolerance / redundancy with my SQL Server Express database. I know that if I upgrade to a pricier version of SQL Server, I can get "Replication" built in. But I'm wondering if anyone has experience in managing replication on the client side. As in, from my application: Every time I need to create, update or delete records from the database -- issue the statement to all n servers directly from the client side Every time I need to read, I can do so from one representative server (other schemes seem possible here, too). It seems like this logic could potentially be added directly to my Linq-To-SQL Data Context. Any thoughts?

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• String to date (Invalid format)

  - by MrThys

  I am using Joda Time library to convert my String dates to a real date, because this seemed like the easiest solution to do this. I am using the DateTime object to do this; new DateTime(strValue); But when inserting some formats it throws me the exception; java.lang.IllegalArgumentException: Invalid format: "Mon, 30 Sep 2002 01:56:02 GMT" java.lang.IllegalArgumentException: Invalid format: "Sun, 29 Sep 2002 19:59:01 GMT" java.lang.IllegalArgumentException: Invalid format: "Mon, 30 Sep 2002 01:52:02 GMT" java.lang.IllegalArgumentException: Invalid format: "Sun, 29 Sep 2002 17:05:20 GMT" java.lang.IllegalArgumentException: Invalid format: "Sun, 29 Sep 2002 19:09:28 GMT" java.lang.IllegalArgumentException: Invalid format: "Sun, 29 Sep 2002 15:01:02 GMT" java.lang.IllegalArgumentException: Invalid format: "Sun, 29 Sep 2002 23:48:33 GMT" java.lang.IllegalArgumentException: Invalid format: "Sun, 29 Sep 2002 17:24:20 GMT" java.lang.IllegalArgumentException: Invalid format: "Sun, 29 Sep 2002 11:13:10 GMT" Is there a way to solve this, or should I use something else instead of DateTime.

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• Symlinking (ln) faster than moving (mv)?

  - by Chad Johnson

  When we build web software releases, we prepare the release in a temporary directory and then replace the release directory with the temporary one just prepared: # Move and replace existing release directory. mv /path/to/httpdocs /path/to/httpdocs.before mv /path/to/$newReleaseName /path/to/httpdocs Under this scheme, it happens that with about 1 in every 15 releases, a user was using a file in the original release directory exactly at the time the commands above are run, and a fatal error occurs for that user. I am wondering if using symlinking like follows would be significantly faster, in terms of processing time, thereby helping to lessen the likelihood of this problem: # Remove and replace existing release symlink. ln -sf /path/to/$newReleaseName path/to/httpdocs

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• Cleanest way to tell if 3 times are within half an hour of each other

  - by niggles

  I have 3 date / time input boxes on a form and the user cannot select any times within half an hour of each other. I've converted all values to epoch format using a Javascript implementation of strtotime, but not sure how to recursively check that any of the times are actually half an hour apart. I can hand code all checks, but it would be cleaner to write a recursive function (especially if there were theoretically more than 3 time slots). Did some Google research but no luck. Any suggestions on implementing this in Javascript or Jquery. Thanks.

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• Castle Windsor - Resolving a generic implementation to a base type

  - by arootbeer

  I'm trying to use Windsor as a factory to provide specification implementations based on subtypes of XAbstractBase (an abstract message base class in my case). I have code like the following: public abstract class XAbstractBase { } public class YImplementation : XAbstractBase { } public class ZImplementation : XAbstractBase { } public interface ISpecification<T> where T : XAbstractBase { bool PredicateLogic(); } public class DefaultSpecificationImplementation : ISpecification<XAbstractBase> { public bool PredicateLogic() { return true; } } public class SpecificSpecificationImplementation : ISpecification<YImplementation> { public bool PredicateLogic() { /*do real work*/ } } My component registration code looks like this: container.Register( AllTypes.FromAssembly(Assembly.GetExecutingAssembly()) .BasedOn(typeof(ISpecification<>)) .WithService.FirstInterface() ) This works fine when I try to resolve ISpecification<YImplementation>; it correctly resolves SpecificSpecificationImplementation. However, when I try to resolve ISpecification<ZImplementation> Windsor throws an exception: "No component for supporting the service ISpecification'1[ZImplementation, AssemblyInfo...] was found" Does Windsor support resolving generic implementations down to base classes if no more specific implementation is registered?

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• Java: startingPath as "public static final" exception

  - by HH

  [Updated] Thanks to polygenelubricants's reply, the real problem is the exception from the method getCanonicalPath() because I cannot include try-catch-loop there. $ cat StartingPath.java import java.util.*; import java.io.*; public class StartingPath { public static final String startingPath = (new File(".")).getCanonicalPath(); public static void main(String[] args){ System.out.println(startingPath); } } $ javac StartingPath.java StartingPath.java:5: unreported exception java.io.IOException; must be caught or declared to be thrown public static final String startingPath = (new File(".")).getCanonicalPath(); ^ 1 error

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• Programming tests: are they relevant?

  - by BlackVoid

  Do online programming tests have any value (except for providing an evidence to potential employers) in terms of evaluating your knowledge, or a they too broad or too narrow in general? For examples, brainbench.com and similar websites. From my experience I have never found myself scoring particularly high, although I have many years of commercial experience and is doing great at work. These tests mostly refer to things I have never worked with (WebForms or ADO .Net, who works with ADO .Net directly anyway?), yet these tests claim to be C# tests. If you were hiring a programmer, would you consider online tests as an evidence of real skill?

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• Microsoft Chart Control labels

  - by Serge

  Hello, I've been searching for a while and browsing through the samples but could not find a solution to my problem. In Microsoft Chart Control I have created a line series that plots real-time data. As new data points are added, the chart margins will sometimes jump on the form. I have tried disabling the grid lines and have determined that the margins change when the x-axis label overlaps with the y-axis label. I have tried auto-fitting the labels but that does not seem to work probably because it treat x-axis and y-axis separately. Is there any way to prevent the overlap, or keep the labels and corresponding grid lines stationery and just change their value when the data scrolls? Thank you for your help.

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• Select from multiple tables, remove duplicates

  - by staze

  I have two tables in a SQLite DB, and both have the following fields: idnumber, firstname, middlename, lastname, email, login One table has all of these populated, the other doesn't have the idnumber, or middle name populated. I'd LIKE to be able to do something like: select idnumber, firstname, middlename, lastname, email, login from users1,users2 group by login; But I get an "ambiguous" error. Doing something like: select idnumber, firstname, middlename, lastname, email, login from users1 union select idnumber, firstname, middlename, lastname, email, login from users2; LOOKS like it works, but I see duplicates. my understanding is that union shouldn't allow duplicates, but maybe they're not real duplicates since the second user table doesn't have all the fields populated (e.g. "20, bob, alan, smith, [email protected], bob" is not the same as "NULL, bob, NULL, smith, [email protected], bob"). Any ideas? What am I missing? All I want to do is dedupe based on "login". Thanks!

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• Space-based architecture?

  - by rcampbell

  One chapter in Pragmatic Programmer recommends looking at a blackboard/space-based architecture + a rules engine as a more flexible alternative to a traditional workflow system. The project I'm working on currently uses a workflow engine, but I'd like to evaluate alternatives. I really feel like a SBA would be a better solution to our business problems, but I'm worried about a total lack of community support/user base/venders/options. JavaSpaces is dead, and the JINI spin-off Apache River seems to be on life support. SemiSpace looks perfect, but it's a one-man show. The only viable solution seems to be GigaSpaces. I'd like to hear your thoughts on space based architecture and any experiences you've had with real world implementations.

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• How to cause AggregateException with TPL?

  - by Sly

  I'm trying to recreate the conditions that will cause this exception: System.AggregateException: A Task's exception(s) were not observed either by Waiting on the Task or accessing its Exception property. As a result, the unobserved exception was rethrown by the finalizer thread.` I wrote this program thinking I'd cause the exception but it does not: using System; using System.Threading.Tasks; namespace SomeAsyncStuff { class Program { static void Main(string[] args) { Task.Factory.StartNew(() => { throw new NullReferenceException("ex"); }); GC.Collect(); Console.WriteLine("completed"); } } } In my real application, I use TPL and I did not code my exception handling right. As a result I get that exception. Now I'm trying to recreate the same conditions in a separate program to experiment with unobserved exceptions.

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• how to implement a "soft barrier" in multithreaded c++

  - by Jason

  I have some multithreaded c++ code with the following structure: do_thread_specific_work(); update_shared_variables(); //checkpoint A do_thread_specific_work_not_modifying_shared_variables(); //checkpoint B do_thread_specific_work_requiring_all_threads_have_updated_shared_variables(); What follows checkpoint B is work that could have started if all threads have reached only checkpoint A, hence my notion of a "soft barrier". Typically multithreading libraries only provide "hard barriers" in which all threads must reach some point before any can continue. Obviously a hard barrier could be used at checkpoint B. Using a soft barrier can lead to better execution time, especially since the work between checkpoints A and B may not be load-balanced between the threads (i.e. 1 slow thread who has reached checkpoint A but not B could be causing all the others to wait at the barrier just before checkpoint B). I've tried using atomics to synchronize things and I know with 100% certainty that is it NOT guaranteed to work. For example using openmp syntax, before the parallel section start with: shared_thread_counter = num_threads; //known at compile time #pragma omp flush Then at checkpoint A: #pragma omp atomic shared_thread_counter--; Then at checkpoint B (using polling): #pragma omp flush while (shared_thread_counter > 0) { usleep(1); //can be removed, but better to limit memory bandwidth #pragma omp flush } I've designed some experiments in which I use an atomic to indicate that some operation before it is finished. The experiment would work with 2 threads most of the time but consistently fail when I have lots of threads (like 20 or 30). I suspect this is because of the caching structure of modern CPUs. Even if one thread updates some other value before doing the atomic decrement, it is not guaranteed to be read by another thread in that order. Consider the case when the other value is a cache miss and the atomic decrement is a cache hit. So back to my question, how to CORRECTLY implement this "soft barrier"? Is there any built-in feature that guarantees such functionality? I'd prefer openmp but I'm familiar with most of the other common multithreading libraries. As a workaround right now, I'm using a hard barrier at checkpoint B and I've restructured my code to make the work between checkpoint A and B automatically load-balancing between the threads (which has been rather difficult at times). Thanks for any advice/insight :)

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• TIBRV: Remote vs Local RVD

  - by jsw

  When connected to a local RVD a sending application is shielded from network interruptions and the send message methods will only block for the time it takes for the message to reach the local RVD process. With remote RVD the sending application is no longer shielded from network interruptions and the send message methods will block for the time it takes to hop across the network to reach the remote RVD process. Is my understanding correct? The documentation is vague regarding remote daemons. I'm mostly concerned with how reliable and performant the send message will be from the perspective of a sending application. Introducing unnecessary blocking on the client side due to sending a message (especially a network hop) is a big no-no in this application. The speed at which the messages reach the consumer is not of the utmost importance. With this in mind is a remote RVD out of the question?

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