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  • OnConnect event not firing when using TClientSocket inside a TThread on non-blocking mode

    - by mathematician1975
    I am trying to make use of Borlands TClientSocket component in non-blocking mode inside a multithreaded C++ Windows application. I am creating multiple threads (classes derived from TThread), each of which creates its own TClientSocket object. I then assign member functions of the thread class to act as event handlers for the OnConnect, OnDisconnect and OnSocketError events of the socket. The problem I am having here is that whenever I call the TClientSocket::Open() function from within the TThread::Execute() function, the OnConnect event never fires. However, When I call the Open() function from the VCL thread prior to the TThread::Execute() function getting called, all of the events fire and I can use the thread-socket combination as I would like. Now I have not read anything in documentation that says that TClientSocket should not be used in non-blocking mode when used inside a thread, but it appears to me that there is perhaps something wrong conceptually in the way I am trying to use this class. Borland documentation is quite poor on the subject and these components have now been deprecated so reliable information is hard to come by. Despite being deprecated I have to use them as there is no alternative in the Builder 6 package I have. Can anyone please advise me if there is a right/wrong way to use TThread and a non-blocking TClientSocket in combination. I have never had problems using it as part of the VCL thread and never had problems using TServerSocket before and I really cannot understand why some events are not firing.

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  • Polling servers at the same port - Threads and Java

    - by John
    Hi there. I'm currently busy working on an IP ban tool for the early versions of Call of Duty 1. (Apparently such a feature wasn't implemented in these versions). I've finished a single threaded application but it won't perform well enough for multiple servers, which is why I am trying to implement threading. Right now, each server has its own thread. I have a Networking class, which has a method; "GetStatus" -- this method is synchronized. This method uses a DatagramSocket to communicate with the server. Since this method is static and synchronized, I shouldn't get in trouble and receive a whole bunch of "Address already in use" exceptions. However, I have a second method named "SendMessage". This method is supposed to send a message to the server. How can I make sure "SendMessage" cannot be invoked when there's already a thread running in "GetStatus", and the other way around? If I make both synchronized, I will still get in trouble if Thread A is opening a socket on Port 99999 and invoking "SendMessage" while Thread B is opening a socket on the same port and invoking "GetStatus"? (Game servers are usually hosted on the same ports) I guess what I am really after is a way to make an entire class synchronized, so that only one method can be invoked and run at a time by a single thread. Hope that what I am trying to accomplish/avoid is made clear in this text. Any help is greatly appreciated.

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  • Design Philosophy Question - When to create new functions

    - by Eclyps19
    This is a general design question not relating to any language. I'm a bit torn between going for minimum code or optimum organization. I'll use my current project as an example. I have a bunch of tabs on a form that perform different functions. Lets say Tab 1 reads in a file with a specific layout, tab 2 exports a file to a specific location, etc. The problem I'm running into now is that I need these tabs to do something slightly different based on the contents of a variable. If it contains a 1 I may need to use Layout A and perform some extra concatenation, if it contains a 2 I may need to use Layout B and do no concatenation but add two integer fields, etc. There could be 10+ codes that I will be looking at. Is it more preferable to create an individual path for each code early on, or attempt to create a single path that branches out only when absolutely required. Creating an individual path for each code would allow my code to be extremely easy to follow at a glance, which in turn will help me out later on down the road when debugging or making changes. The downside to this is that I will increase the amount of code written by calling some of the same functions in multiple places (for example, steps 3, 5, and 9 for every single code may be exactly the same. Creating a single path that would branch out only when required will be a bit messier and more difficult to follow at a glance, but I would create less code by placing conditionals only at steps that are unique. I realize that this may be a case-by-case decision, but in general, if you were handed a previously built program to work on, which would you prefer?

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  • Sharing same vector control between different places

    - by Alexander K
    Hi everyone, I'm trying to implement the following: I have an Items Manager, that has an Item class inside. Item class can store two possible visual representations of it - BitmapImage(bitmap) and UserControl(vector). Then later, in the game, I need to share the same image or vector control between all possible places it takes place. For example, consider 10 trees on the map, and all point to the same vector control. Or in some cases this can be bitmap image source. So, the problem is that BitmapImage source can be easily shared in the application by multiple UIElements. However, when I try to share vector control, it fails, and says Child Element is already a Child element of another control. I want to know how to organize this in the best way. For example replace UserControl with other type of control, or storage, however I need to be sure it supports Storyboard animations inside. The code looks like this: if (bi.item.BitmapSource != null) { Image previewImage = new Image(); previewImage.Source = bi.item.BitmapSource; itemPane.ItemPreviewCanvas.Children.Add(previewImage); } else if (bi.item.VectorSource != null) { UserControl previewControl = bi.item.VectorSource; itemPane.ItemPreviewCanvas.Children.Add(previewControl); } Thanks in advance

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  • Going "behind Hibernate's back" to update foreign key values without an associated entity

    - by Alex Cruise
    Updated: I wound up "solving" the problem by doing the opposite! I now have the entity reference field set as read-only (insertable=false updatable=false), and the foreign key field read-write. This means I need to take special care when saving new entities, but on querying, the entity properties get resolved for me. I have a bidirectional one-to-many association in my domain model, where I'm using JPA annotations and Hibernate as the persistence provider. It's pretty much your bog-standard parent/child configuration, with one difference being that I want to expose the parent's foreign key as a separate property of the child alongside the reference to a parent instance, like so: @Entity public class Child { @Id @GeneratedValue Long id; @Column(name="parent_id", insertable=false, updatable=false) private Long parentId; @ManyToOne(cascade=CascadeType.ALL) @JoinColumn(name="parent_id") private Parent parent; private long timestamp; } @Entity public class Parent { @Id @GeneratedValue Long id; @OrderBy("timestamp") @OneToMany(mappedBy="parent", cascade=CascadeType.ALL, fetch=FetchType.LAZY) private List<Child> children; } This works just fine most of the time, but there are many (legacy) cases when I'd like to put an invalid value in the parent_id column without having to create a bogus Parent first. Unfortunately, Hibernate won't save values assigned to the parentId field due to insertable=false, updatable=false, which it requires when the same column is mapped to multiple properties. Is there any nice way to "go behind Hibernate's back" and sneak values into that field without having to drop down to JDBC or implement an interceptor? Thanks!

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  • Connecting to an RMI object without registry

    - by Mark Probst
    I think I need to connect to a remote RMI object without going through the registry, but I don't know how. My situation is this: I'm implementing a simple job distribution service which consists of one distributor and multiple workers. The distributor has a registered RMI object to which clients connect to send jobs, and workers connect to accept jobs. Unfortunately the distributor and worker hosts are behind a firewall. To get to the distributor host I am tunneling two ports (one for the registry, one for the distributor object) via SSH, so I can get to the registry and the distributor from outside the firewall. To make that work I have to set "-Djava.rmi.server.hostname=localhost" on the distributor JVM so that the clients connect to their local, tunneled port, instead of the port on the actual distributor host, which is blocked. This creates a problem for the workers, though, because they need to connect to the distributor directly, but because of the "localhost" redirection they behave like clients and try to connect to a port on their own host, which is not available, because I'm not tunneling on the workers (it is impractical). Now, if I could connect to a remote object directly by giving the hostname and port, I could do away both with the registry on the distributor and the "localhost" hack, and make the workers connect properly. How do I do that? Or is there a different solution to this problem?

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  • Client-server synchronization pattern / algorithm?

    - by tm_lv
    I have a feeling that there must be client-server synchronization patterns out there. But i totally failed to google up one. Situation is quite simple - server is the central node, that multiple clients connect to and manipulate same data. Data can be split in atoms, in case of conflict, whatever is on server, has priority (to avoid getting user into conflict solving). Partial synchronization is preferred due to potentially large amounts of data. Are there any patterns / good practices for such situation, or if you don't know of any - what would be your approach? Below is how i now think to solve it: Parallel to data, a modification journal will be held, having all transactions timestamped. When client connects, it receives all changes since last check, in consolidated form (server goes through lists and removes additions that are followed by deletions, merges updates for each atom, etc.). Et voila, we are up to date. Alternative would be keeping modification date for each record, and instead of performing data deletes, just mark them as deleted. Any thoughts?

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  • How do I write an RSpec test to unit-test this interesting metaprogramming code?

    - by Kyle Kaitan
    Here's some simple code that, for each argument specified, will add specific get/set methods named after that argument. If you write attr_option :foo, :bar, then you will see #foo/foo= and #bar/bar= instance methods on Config: module Configurator class Config def initialize() @options = {} end def self.attr_option(*args) args.each do |a| if not self.method_defined?(a) define_method "#{a}" do @options[:"#{a}"] ||= {} end define_method "#{a}=" do |v| @options[:"#{a}"] = v end else throw Exception.new("already have attr_option for #{a}") end end end end end So far, so good. I want to write some RSpec tests to verify this code is actually doing what it's supposed to. But there's a problem! If I invoke attr_option :foo in one of the test methods, that method is now forever defined in Config. So a subsequent test will fail when it shouldn't, because foo is already defined: it "should support a specified option" do c = Configurator::Config c.attr_option :foo # ... end it "should support multiple options" do c = Configurator::Config c.attr_option :foo, :bar, :baz # Error! :foo already defined # by a previous test. # ... end Is there a way I can give each test an anonymous "clone" of the Config class which is independent of the others?

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  • Problem with 2 levels of inheritance in hibernate mapping

    - by Seth
    Here's my class structure: class A class B extends A class C extends A class D extends C class E extends C And here are my mappings (class bodies omitted for brevity): Class A: @Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @MappedSuperclass @DiscriminatorColumn( name="className", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class A Class B: @Entity @DiscriminatorValue("B") public class B extends A Class C: @Entity @DiscriminatorValue("C") @MappedSuperclass @DiscriminatorColumn( name="cType", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class C extends A Class D: @Entity @DiscriminatorValue("D") public class D extends C Class E: @Entity @DiscriminatorValue("E") public class E extends C I've got a class F that contains a set of A: @Entity public class F { ... @OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL) @JoinTable( name="F_A", joinColumns = @JoinColumn(name="A_ID"), inverseJoinColumns = @JoinColumn(name="F_ID") ) private Set<A> aSet = new HashSet<A>(); ... The problem is that whenever I add a new E instance to aSet and then call session.saveOrUpdate(fInstance), hibernate saves with "A" as the discrimiator string. When I try to access the aSet in the F instance, I get the following exception (full stacktrace ommitted for brevity): org.hibernate.InstantiationException: Cannot instantiate abstract class or interface: path.to.class.A Am I mapping the classes incorrectly? How am I supposed to map multiple levels of inheritance? Thanks for the help!

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  • Why should I care about RVM's Gemset feature when I use Bundler?

    - by t6d
    I just don't get it. I thought, Bundler was developed to resolve version conflicts between gems. So that I just have to require "bundler/setup" and everything is fine, knowing that Bundler will load the correct versions of all my gems and their dependencies. Now, RVM is great for managing multiple Rubies, I know, but why should I care about the Gemset feature? Do I miss something here? Can it make my development even easier? Maybe, some of you can give me some hints on the perfect RVM + Bundler workflow for both, development and production. I also don't know when RVM starts switching to another Ruby. I know that I can have an .rvmrc file in my project, but do I have to cd to this directory so that the switch happens? Furthermore, I usually use Passenger for development since, thanks to the Passenger.prefpane, integration in Mac OS is great. Can I still do that with RVM or is there a better way to do it? Does Passenger recognize .rvmrc files and switch to the correct Gemset?

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  • create controls at run-time in .net

    - by ahmed naguib
    i add a course then search in students grid view and select multiple students after i choose students say they are 50 student user enter the number of students in each group say =10 mean that i will have 5 groups each group contain 10 student when user click button a five container appear whatever these container are ul or listboxes user can move one student from one group to another group cause every group start course at specific date notice : number of students user determine it and number of students in each group also user determine container i didnot decide ul as i will write or text boxes but how to transfer student from one listbox to another <ul group1> <li>student1</li> <li>student2</li> <li>student3</li> <li>student4</li> <li>student5</li> </ul> <ul group1> <li>student1</li> <li>student2</li> <li>student3</li> <li>student4</li> <li>student5</li> </ul>

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  • What is happening in Crockford's object creation technique?

    - by Chris Noe
    There are only 3 lines of code, and yet I'm having trouble fully grasping this: Object.create = function (o) { function F() {} F.prototype = o; return new F(); }; newObject = Object.create(oldObject); (from Prototypal Inheritance) 1) Object.create() starts out by creating an empty function called F. I'm thinking that a function is a kind of object. Where is this F object being stored? Globally I guess. 2) Next our oldObject, passed in as o, becomes the prototype of function F. Function (i.e., object) F now "inherits" from our oldObject, in the sense that name resolution will route through it. Good, but I'm curious what the default prototype is for an object, Object? Is that also true for a function-object? 3) Finally, F is instantiated and returned, becoming our newObject. Is the "new" operation strictly necessary here? Doesn't F already provide what we need, or is there a critical difference between function-objects and non-function-objects? Clearly it won't be possible to have a constructor function using this technique. What happens the next time Object.create() is called? Is global function F overwritten? Surely it is not reused, because that would alter previously configured objects. And what happens if multiple threads call Object.create(), is there any sort of synchronization to prevent race conditions on F?

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  • Why is Chrome miscalculating jQuery submenu dimensions?

    - by chunkymonkey
    I'm trying to implement this dropdown menu with flyouts: http://jsfiddle.net/chunkymonkey/fr6x4/ In Chrome certain categories can be expanded to show their subcategories while others show nothing when opened up. For example: Alternative Rock can be expanded to show its multiple subcategories . . . BUT . . . World Music, which has as many subcategories, shows no subcategories when expanded. (SCREENSHOT: http://i.imgur.com/0WorR.jpg) I thought I had tracked this problem down to a problem with they way the dimensions of the dropdown elements are calculated in the original code: First change: - var newLeftVal = - ($('.fg-menu-current').parents('ul').size() - 1) * 180; + var newLeftVal = - ($('.fg-menu-current').parents('ul').size() - 1) * container.width(); Second change: Remove: var checkMenuHeight = function(el) { if (el.height() > options.maxHeight) { el.addClass('fg-menu-scroll') }; el.css({ height: options.maxHeight }); }; Add: var checkMenuHeight = function(el) { var max_height = options.maxHeight - breadcrumb.getTotalHeight(); if (el.height() > max_height) { el.addClass('fg-menu-scroll'); el.height(max_height); topList.height(max_height); } else { if (topList.height() < el.height()) { topList.height(el.height()); } } }; But it's still not working only on Chrome (version 8, Windows & Mac) (not sure why Chrome is different).

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  • SQLBrowser will not start

    - by Oliver
    SQL Server 2005 x64 on Windows Server 2003 x64, with multiple instances (default + 2 named). Engineers moved server to a different domain. Since then, cannot get SQLBrowser to start. Still able to query the default instance, and can access named instances by port (TCP:hostname,port#). When on server, can use SSMS to connect to the instances, all is well from that perspective. No errors in the SQL Server logs. As SQLBrowser is starting, an entry in EventViewer.Application says that one of the named instances has an invalid configuration, but I haven't been able to figure out what is invalid. Startup continues, and next message says "The SQLBrowser service was unable to establish SQL instance and connectivity discovery." Next, it enables instance and connectivity discovery support; next, another message about that same named instance having an invalid configuration; then an event says that SQLBrowser has started; last, an event shows the SQLBrowser service has shutdown. I got SQLBrowser to get past the issue with the first named instance by temporarily renaming a registry entry, and now the second named instance can be accessed by name rather than port. Still, cannot access the first named instance by name. Advice?

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  • Maven3 Issues with building a multi-module enterprise project

    - by Sujit K
    I just migrated from Maven2 to Maven3 and I'm able to build each module individually or all the modules in one shot by calling mvn clean install. However, in Maven2, since we have multi-module enterprise project, we build multiple ear's and each ear is built as its own module with its own child pom. To build an individual ear with its dependents, the below command works fine in Maven2 but not in Maven3. Let me explain the issue in Maven3 a bit later. mvn -pl ear_module -rf first_dependent_module -am clean install In Maven2 when the reactor lists the build order, I see first_dependent_module second_dependent_module ear_module End of the day I have my ear module also part of the reactor which is how it should be. The reason we call -rf is we don't want to delete the target folder at the main ${project.basedir} (so not to delete the output created in target from building the other ear modules). With Maven3, however, this is all I see when the reactor lists the build order: first_dependent_module second_dependent_module Maven3 totally ignores the argument (ear_module) set to -pl flag to be also built after its dependents have been. Not sure what I'm missing here. Any help/tips would be greatly appreciated. P.S: The build I'm making is similar to the one below.... Build specific module in multi-module project Thanks, SK

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  • Catching specific vs. generic exceptions in c#

    - by Scott Vercuski
    This question comes from a code analysis run against an object I've created. The analysis says that I should catch a more specific exception type than just the basic Exception. Do you find yourself using just catching the generic Exception or attempting to catch a specific Exception and defaulting to a generic Exception using multiple catch blocks? One of the code chunks in question is below: internal static bool ClearFlags(string connectionString, Guid ID) { bool returnValue = false; SqlConnection dbEngine = new SqlConnection(connectionString); SqlCommand dbCmd = new SqlCommand("ClearFlags", dbEngine); SqlDataAdapter dataAdapter = new SqlDataAdapter(dbCmd); dbCmd.CommandType = CommandType.StoredProcedure; try { dbCmd.Parameters.AddWithValue("@ID", ID.ToString()); dbEngine.Open(); dbCmd.ExecuteNonQuery(); dbEngine.Close(); returnValue = true; } catch (Exception ex) { ErrorHandler(ex); } return returnValue; } Thank you for your advice EDIT: Here is the warning from the code analysis Warning 351 CA1031 : Microsoft.Design : Modify 'ClearFlags(string, Guid)' to catch a more specific exception than 'Exception' or rethrow the exception

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  • How to check whether user is login in web application?

    - by Morgan Cheng
    I want to learn the whole details of web application authentication. So, I decided to write a CodeIgniter authentication library from scratch. Now, I have to make design decision about how to determine whether one user is login. Basically, after user input username & password pair. A cookie is set for this session, following navigations in the web application will not require username & password. The server side will check whether the session cookie is valid to determine whether current user is login. The question is: how to determine whether cookie is valid cookie issued from server side? I can image the most simple way is to have the cookie value stored in session status as well. For each HTTP request, compare the value from cookie and the value from server session. (Since CodeIgniter session library store session variables in cookies, it is not applicable without some tweak.) This method requires storage in server side. For huge web application that is deployed in multiple datacenters. It is possible that user input username & password when browsing in one datacenter, while he/she access the web application in another datacenter later. The expected behavior is that user just input username & password once. As a result, all datacenters should be able to access the session status. That is possible not applicable even the session status is stored in external storage such as database. I tried Google. I login Google with Asian proxy which is supposed to direct me to datacenters in Asian. Then I switch to North American proxy which should direct me to datacenters in North America. It recognize my login without asking username and password again. So, is there any way to determine whether user is login without server side session status?

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  • Same session and session ID for different subdomains in Grails project - How can I do that?

    - by fluxon
    I am currently working on a project that supports multiple languages. In order to be seo friendly, I am trying to redirect users subdomains corresponding to their locale (or their preferred language). I.e., my projects's url is mydomain.com and I work with the subdomains en.mydomain.com, es.mydomain.com, de.mydomain.com, fr.mydomain.com ... you get the idea. All subdomains are served by the same grails app for now. What happens is that my grails project maintains different sessions (as seen by the session ids) for every single subdomain, hence information is lost, when a user switches between languages. I had not forseen that. :( How can I explicitly set the session identifier? I would like it to be based on just mydomain.com. I got the hint that Apache Tomcat offers something like <Context sessionCookiePath="/" sessionCookieDomain=".mydomain.com"> , but that does not help for the devel environment etc. Any hints? Have you tried storing session information in the DB? This is sometimes used for load-balancing purposes and might help here as well?! Help is highly appreciated (as always)! Cheers!

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  • Programming an IPTV application- Client/Server

    - by Sumit Ghosh
    I am part of a team which has been given a task to deploy an IPTV solution for a company. The system has been architect-ed like this. There is Video capture card , which receives satellite signals from a satellite receiver. This video capture card is part of a windows 7 machine. The signals need to be trans coded here and passed to a streaming server which will be received by end users. The end users will be desktop users having a C#.NET application installed to view the channels. I am confused at the choice of server software as I have multiple choices - Windows Media Server, VideoLan (VLC project), or Flash Media Server, it also supports MPEG-2 HD. My main aim to be able to stream MPEG-2 channels with HD quality and encrypt the channels at the server end so that the streams can be protected. I know reversing is possible but it wont be easy as for every naive user with wireshark snooping my streams. If any of you here has ever done such an implementation please do suggest me the best technologies I should go for. Iam open to C#,C++ and other similar languages. Any help shall be deeply appreciated. edit: End Users shall be part of Internet and not necessarily a lan, reason for this question is internet doesn't support multicast like Lan, so I need some suggestions.

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  • How to Treat Race Condition of Session in Web Application?

    - by Morgan Cheng
    I was in a ASP.NET application has heavy traffic of AJAX requests. Once a user login our web application, a session is created to store information of this user's state. Currently, our solution to keep session data consistent is quite simple and brutal: each request needs to acquire a exclusive lock before being processed. This works fine for tradition web application. But, when the web application turns to support AJAX, it turns to not efficient. It is quite possible that multiple AJAX requests are sent to server at the same time without reloading the web page. If all AJAX requests are serialized by the exclusive lock, the response is not so quick. Anyway, many AJAX requests that doesn't access same session variables are blocked as well. If we don't have a exclusive lock for each requests, then we need to treat all race condition carefully to avoid dead lock. I'm afraid that would make the code complex and buggy. So, is there any best practice to keep session data consistent and keep code simple and clean?

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  • Database structure for ecommerce site

    - by imanc
    Hey Guys, I have been tasked with designing an ecommerce solution. The aspect that is causing me the most problems is the database. Currently the site consists of 10+ country based shops each with their own database (all residing on the same mysql instance). For the new site I'd rather all these shop databases be merged into one database so that all tables (products, orders, customers etc.) have a shop_id field. From a programming perspective this seems to make the most sense as we won't have to manage data across multiple databases. Currently the entire site generates about 120k orders a year, but is experiencing fairly heavy growth and we need to design a solution that will scale. In 5 years there may be more than a million orders per year and a database that contains 5 years order history (archiving maybe a solution here). The question is - do we use a single database, or do we keep the database-per-shop structure? I am currently trying to find supporting evidence for either avenue. The company I am designing the solution for prefer the per-shop database structure because they believe it will allow the sites to scale. But my argument is that the shop's database probably won't get that busy over the next few years that they exceed the capacity of a mysql database and a "no expenses spared" hardware set-up. I am wondering if anyone has any advice either way? Does anyone have experience with websites / ecommerce sites that have tables containing millions of records? I know there is probably not a clear answer here, but at what stage do we have too many records or too large table files to have a fast loading site? Also, if anyone has any advice on sources of information - books, websites, etc. where I can do further research, it would be highly appreciated! Cheers, imanc

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  • SQL trigger to delete rows from database

    - by wpearse
    I have an industrial system that logs alarms to a remotely hosted MySQL database. The industrial system inserts a new row whenever a property of the alarm changes (such as the time the alarm was activated, acknowledged or switched off) into a table named 'alarms'. I don't want multiple records for each alarm, so I have set up two database triggers. The first trigger mirrors each new record to a second table, creating/updating rows as required: CREATE TRIGGER `mirror_alarms` BEFORE INSERT ON `alarms` FOR EACH ROW INSERT INTO `alarm_display` (Tag,...,OffTime) VALUES (new.Tag,...,new.OffTime) ON DUPLICATE KEY UPDATE OnDate=new.OnDate,...,OffTime=new.OffTime The second trigger should execute after the first and (ideally) delete all rows from the alarms table. (I used the Tag property of the alarm because the Tag property never changes, although I suspect I could just use a 'DELETE FROM alarms WHERE 1' statement to the same effect). CREATE TRIGGER `remove_alarms` AFTER INSERT ON `alarms` FOR EACH ROW DELETE FROM alarms WHERE Tag=new.Tag My problem is that the second trigger doesn't appear to run, or if it does, the second trigger doesn't delete any rows from the database. So here's the question: why does my second trigger not do what I expect it to do?

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  • How to properly implement the Strategy pattern in a web MVC framework?

    - by jboxer
    In my Django app, I have a model (lets call it Foo) with a field called "type". I'd like to use Foo.type to indicate what type the specific instance of Foo is (possible choices are "Number", "Date", "Single Line of Text", "Multiple Lines of Text", and a few others). There are two things I'd like the "type" field to end up affecting; the way a value is converted from its normal type to text (for example, in "Date", it may be str(the_date.isoformat())), and the way a value is converted from text to the specified type (in "Date", it may be datetime.date.fromtimestamp(the_text)). To me, this seems like the Strategy pattern (I may be completely wrong, and feel free to correct me if I am). My question is, what's the proper way to code this in a web MVC framework? In a client-side app, I'd create a Type class with abstract methods "serialize()" and "unserialize()", override those methods in subclasses of Type (such as NumberType and DateType), and dynamically set the "type" field of a newly-instantiated Foo to the appropriate Type subclass at runtime. In a web framework, it's not quite as straightforward for me. Right now, the way that makes the most sense is to define Foo.type as a Small Integer field and define a limited set of choices (0 = "Number", 1 = "Date", 2 = "Single Line of Text", etc.) in the code. Then, when a Foo object is instantiated, use a Factory method to look at the value of the instance's "type" field and plug in the correct Type subclass (as described in the paragraph above). Foo would also have serialize() and unserialize() methods, which would delegate directly to the plugged-in Type subclass. How does this design sound? I've never run into this issue before, so I'd really like to know if other people have, and how they've solved it.

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  • When should we use Views, Temporary Tables and Direct Queries ? What are the Performance issues in a

    - by Shantanu Gupta
    I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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  • Issue with Callback method and maintaining CultureInfo and ASP.Net HttpRuntime

    - by Little Larry Sellers
    Hi All, Here is my issue. I am working on an E-commerce solution that is deployed to multiple European countries. We persist all exceptions within the application to SQL Server and I have found that there are records in the DB that have a DateTime in the future! We define the culture in the web.config, for example pt-PT, and the format expected is DD-MM-YYYY. After debugging I found the issue with these 'future' records in the DB is because of Callback methods we use. For example, in our Caching architecture we use Callbacks, as such - CacheItemRemovedCallback ReloadCallBack = new CacheItemRemovedCallback(OnRefreshRequest); When I check the current threads CultureInfo, on these Callbacks it is en-US instead of pt-PT and also the HttpContext is null. If an exception occurs on the Callback our exception manager reports it as MM-DD-YYYY and thus it is persisted to SQL Server incorrectly. Unfortunately, in the exception manager code, we use DateTime.Now, which is fine if it is not a callback. I can't change this code to be culture specific due to it being shared across other verticals. So, why don't callbacks into ASP.Net maintain context? Is there any way to maintain it on this callback thread? What are the best practices here? Thanks.

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