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• Implementing BindingList<T>

  - by EtherealMonkey

  I am trying to learn more about BindingList because I believe that it will help me with a project that I am working on. Currently, I have an object class (ScannedImage) that is a subtype of a class (HashedImage) that subtypes a native .Net object (Image). There is no reason why I couldn't move the two subtypes together. I am simply subtyping an object that I had previously constructed, but I will now be storing my ScannedImage object in an RDB (well, not technically - only the details and probably the thumbnail). Also, the object class has member types that are my own custom types (Keywords). I am using a custom datagridview to present these objects, but am handling all changes to the ScannedImage object with my own code. As you can probably imagine, I have quite a few events to handle that occur in these base types. So, if I changed my object to implement INotifyPropertyChanged, would the object collection (implementing BindingList) receive notifications of changes to the ScannedImage object? Also, if Keywords were to implement INotifyPropertyChanged, would changes be accessible to the BindingList through the ScannedImage object? Sorry if this seems rather newbish. I only recently discovered the BindingList and not having formal training in C# programming - am having a difficult time moving forward with this. Also, if anyone has any good reference material, I would be thankful for links. Obviously, I have perused the MSDN Library. I have found a few good links on the web, but it seems that a lot of people are now using WPF and ObservableCollection. My project is based on Winforms and .Net3.5 framework. TIA

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• Auto switching databases from a rails app gracefully from the ApplicationController?

  - by Zaqintosh

  I've seen this post a few times, but haven't really found the answer to this specific question. I'd like to run a rails application that based on the detected request.host (imagine I have two subdomains points to the same rails app and server ip address: myapp1.domain.com and myapp2.domain.com). I'm trying to have myapp1 use the default "production" database, and myapp2 requests always use the alternative remote database. Here is an example of what I tried to do in Application controller that did not work: class ApplicationController < ActionController::Base helper :all before_filter :use_alternate_db private def use_alternate_db if request.host == 'myapp1.domain.com' regular_db elsif request.host == 'myapp2.domain.com' alternate_db end end def regular_db ActiveRecord::Base.establish_connection :production end def alternate_db ActiveRecord::Base.establish_connection( :adapter => 'mysql', :host => '...', :username => '...', :password => '...', :database => 'alternatedb' ) end end The problem is when it switches databases using this method, all connections (including valid sessions across the different subdomains get interrupted...). All examples online have people controlling database connectivity at the model level, but this would involve adding code all over my application. Is there some way to globally switch database connections on a per-request basis in the manner I'm suggesting above WITHOUT having to inject code all over my application? The added complexity here is I'm using Heroku as a hosting provider, so I have no control at the apache / rails application server level. I have looked at solutions like dbcharmer and magicmodels, but none seem to show examples of doing it in the manner that I'm trying to. Thanks for any help!

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• Address Match Key Algorithm

  - by sestocker

  I have a list of addresses in two separate tables that are slightly off that I need to be able to match. For example, the same address can be entered in multiple ways: 110 Test St 110 Test St. 110 Test Street Although simple, you can imagine the situation in more complex scenerios. I am trying to develop a simple algorithm that will be able to match the above addresses as a key. For example. the key might be "11TEST" - first two of 110, first two of Test and first two of street variant. A full match key would also include first 5 of the zipcode as well so in the above example, the full key might look like "11TEST44680". I am looking for ideas for an effective algorithm or resources I can look at for considerations when developing this. Any ideas can be pseudo code or in your language of choice. We are only concerned with US addresses. In fact, we are only looking at addresses from 250 zip codes from Ohio and Michigan. We also do not have access to any postal software although would be open to ideas for cost effective solutions (it would essentially be a one time use). Please be mindful that this is an initial dump of data from a government source so suggestions of how users can clean it are helpful as I build out the application but I would love to have the best initial I possibly can by being able to match addresses as best as possible.

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• Git-svn branch hoses dcommit when using an odd branch structure

  - by Chuck Vose

  I had a boss, past-tense, who decided to put svn branches in the same folder as trunk. Normally, this wouldn't affect me that much but since I'm using git-svn things are going so well. After I did a fetch it created a folder for each branch in my root folder so I have three folders, drupal, trunk, and client. The drupal folder is git's master branch, client and trunk are the svn branches. Merging and committing works great, in fact everything git related is working superb. However dcommit is totally hosed, it's trying to commit a folder called client and one called trunk. I can't even imagine what havoc this would cause for svn later on. So my question is, what have I done wrong in my .git/config and is there anything I can do to fix this or am I going to have to suffer and go back to using svn? Please don't make me go back. I don't think I can take it anymore. Bastard boss knows how to leave a legacy. [svn-remote "svn"] url = https://svn.mydomain.com/svn/project_name fetch = trunk:refs/remotes/trunk branches = *:refs/remotes/* tags = tags/*:refs/remotes/tags/* Normally the branches line would look like this (when using --stdlayout): branches = branches/*:refs/remotes/branches/* ls output is thus: $ ls client/ docs/ drupal/ sql/ trunk/

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• How to exploit Diffie-hellman to perform a man in the middle attack

  - by jfisk

  Im doing a project where Alice and Bob send each other messages using the Diffie-Hellman key-exchange. What is throwing me for a loop is how to incorporate the certificate they are using in this so i can obtain their secret messages. From what I understand about MIM attakcs, the MIM acts as an imposter as seen on this diagram: Below are the details for my project. I understand that they both have g and p agreed upon before communicating, but how would I be able to implement this with they both having a certificate to verify their signatures? Alice prepares ?signA(NA, Bob), pkA, certA? where signA is the digital signature algorithm used by Alice, “Bob” is Bob’s name, pkA is the public-key of Alice which equals gx mod p encoded according to X.509 for a fixed g, p as specified in the Diffie-Hellman key- exchange and certA is the certificate of Alice that contains Alice’s public-key that verifies the signature; Finally, NA is a nonce (random string) that is 8 bytes long. Bob checks Alice's signature, and response with ?signB{NA,NB,Alice},pkB,certB?. Alice gets the message she checks her nonce NA and calculates the joint key based on pkA, pkB according to the Diffie-Hellman key exchange. Then Alice submits the message ?signA{NA,NB,Bob},EK(MA),certA? to Bob and Bobrespondswith?SignB{NA,NB,Alice},EK(MB),certB?. where MA and MB are their corresponding secret messages.

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• Determing size of visible area of a ScrollingGraphicalViewer in Eclipse GEF

  - by Simon

  I am attempting to create a simple application using Eclipse GEF that displays a diagram inside a ScrollingGraphicalViewer. On start-up I want the diagram to be centered inside the viewer (imagine a star layout where the center of the star is in the center of the view). Here are what I think are the relevant code sections: My view: public class View extends ViewPart { public static final String ID = "GEFProofOfConcept.view"; ... public void createPartControl(Composite parent) { viewer.createControl(parent); viewer.setRootEditPart(rootEditPart); viewer.setEditPartFactory(editPartFactory); viewer.setContents(DummyModelCreator.generateModel()); } The edit part code: @Override protected void refreshVisuals() { Project project = (Project) getModel(); // This is where the actual drawing is done, // Simply a rectangle with text Rectangle bounds = new Rectangle(50, 50, 75, 50); getFigure().setBounds(bounds); Label label = new Label(project.getName()); projectFont = new Font(null, "Arial", 6, SWT.NORMAL); label.setFont(projectFont); label.setTextAlignment(PositionConstants.CENTER); label.setBounds(bounds.crop(IFigure.NO_INSETS)); getFigure().add(label); setLocation(); } private void setLocation() { Project project = (Project) getModel(); if (project.isRoot()) { // Place in centre of the layout Point centrePoint = new Point(0, 0); // This is where I need the center of the view getFigure().setLocation(centrePoint); } else { ... } } And the parent of the above edit part: public class ProjectDependencyModelEditPart extends AbstractGraphicalEditPart { @Override protected IFigure createFigure() { Figure f = new FreeformLayer(); f.setLayoutManager(new XYLayout()); return f; } ... Alternative solutions to the problem also welcome, I am most certainly a GEF (and Eclipse in general) newbie.

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• visual studio 2008 vs 2010 Pro unmanaged code

  - by bartek

  Hi, I'm a C++ programmer, I use Visual Studio 2008 Professional, only unmanaged code. I'm thinking of buying VS 2010 Pro. I'm confused, I don't know what are differences between those two. I know that, in plus, it has tr1 included. When I started using 2008 edition I was very pleased to see f.e. unit testing support but all new features are only for managed code. The C++ debugger in 2008 is very good, better than 2003 edition one. I would't like to buy a new tool and discover that I gained nothing and lost some functionality ( because f.e. something was moved to higher version). Once upon a time I switched from very good VS6 to VS 2003.Net and imagine what, after some time I discovered that Pro has no support for code optimalization. It is wonderful how Microsoft makes money. I wouldn't like to experience something like that again. What do you think, what can you recommended?

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• How do I use a different image for each JQuery UI Slider handle

  - by Tom

  I'm using a JQuery UI slider which has two handles (a.k.a range slider). I know how to style the first handle: .ui-slider-horizontal .ui-slider-handle {background: white url(http://stackoverflow.com/content/img/so/vote-arrow-down.png) no-repeat scroll 50% 50%;} But how do I style the second handle differently? Using Firebug I can see Jquery does not uniquely identify each handle: <div id="hourlyRateSlider" class="ui-slider ui-slider-horizontal ui-widget ui-widget-content ui-corner-all"> <div class="ui-slider-range ui-widget-header" style="left: 26%; width: 46%;"/> <a class="ui-slider-handle ui-state-default ui-corner-all" href="#" style="left: 26%;"/> <a class="ui-slider-handle ui-state-default ui-corner-all" href="#" style="left: 72%;"/> </div> So I imagine I have to use either a CSS child selector which could be cross-browser problematic. Or I could use some JQuery trickery to add a CSS class to the second handle? Anyone done this in a neat way before?

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• StackOverFlowException - but oviously NO recursion/endless loop

  - by user567706

  Hi there, I'm now blocked by this problem the entire day, read thousands of google results, but nothing seems to reflect my problem or even come near to it... i hope any of you has a push into the right direction for me. I wrote a client-server-application (so more like 2 applications) - the client collects data about his system, as well as a screenshot, serializes all this into a XML stream (the picture as a byte[]-array]) and sends this to the server in regular intervals. The server receives the stream (via tcp), deserializes the xml to an information-object and shows the information on a windows form. This process is running stable for about 20-25 minutes at a submission interval of 3 seconds. When observing the memory usage there's nothing significant to see, also kinda stable. But after these 20-25 mins the server throws a StackOverflowException at the point where it deserializes the tcp-stream, especially when setting the Image property from the byte[]-array. I thoroughly searched for recursive or endless loops, and regarding the fact that it occurs after thousands of sucessfull intervals, i could hardly imagine that. public byte[] ImageBase { get { MemoryStream ms = new MemoryStream(); _screen.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); return ms.GetBuffer(); } set { if (_screen != null) _screen.Dispose(); //preventing well-known image memory leak MemoryStream ms = new MemoryStream(value); try { _screen = Image.FromStream(ms); //<< EXCEPTION THROWING HERE } catch (StackOverflowException ex) //thx to new CLR management this wont work anymore -.- { Console.WriteLine(ex.Message + Environment.NewLine + ex.StackTrace); } ms.Dispose(); ms = null; } } I hope that more code would be unnecessary, or it could get very complex... Please help, i have no clue at all anymore thx Chris

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• choosing row (from group) with max value in a SQL Server Database

  - by sriehl

  I have a large database and am putting together a report of the data. I have aggregated and summed the data from many tables to get two tables that look like the following. id | code | value id | code | value 13 | AA | 0.5 13 | AC | 2.0 13 | AB | 1.0 14 | AB | 1.5 14 | AA | 2.0 13 | AA | 0.5 15 | AB | 0.5 15 | AB | 3.0 15 | AD | 1.5 15 | AA | 1.0 I need to get a list of id's, with the code (sumed from both tables) with the largest value. 13 | AC 14 | AA 15 | AB There are 4-6 thousand records and it is not possible to change the original tables. I'm not too worried about performance as I only need to run it a few times a year. edit: Let me see if I can explain a bit more clearly, imagine the id is the customer id, the code is who they ordered from and the value is how much they spent there. I need a list of the all the customer id's and the store that customer spent the most money at (and if they spent the same at two different stores, put a value such as 'ZZ' in for the store name).

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• mtl, transformers, monads-fd, monadLib, and the paradox of choice

  - by yairchu

  Hackage has several packages for monad transformers: mtl: Monad transformer library transformers: Concrete functor and monad transformers monads-fd: Monad classes, using functional dependencies monads-tf: Monad classes, using type families monadLib: A collection of monad transformers. mtl-tf: Monad transformer library using type families mmtl: Modular Monad transformer library mtlx: Monad transformer library with type indexes, providing 'free' copies. compose-trans: Composable monad transformers (and maybe I missed some) Which one shall we use? mtl is the one in the Haskell Platform, but I keep hearing on reddit that it's uncool. But what's bad about choice anyway, isn't it just a good thing? Well, I saw how for example the authors of data-accessor had to make all these to cater to just the popular choices: data-accessor-monadLib library: Accessor functions for monadLib's monads data-accessor-monads-fd library: Use Accessor to access state in monads-fd State monad class data-accessor-monads-tf library: Use Accessor to access state in monads-tf State monad type family data-accessor-mtl library: Use Accessor to access state in mtl State monad class data-accessor-transformers library: Use Accessor to access state in transformers State monad I imagine that if this goes on and for example several competing Arrow packages evolve, we might see something like: spoonklink-arrows-transformers, spoonklink-arrows-monadLib, spoonklink-tfArrows-transformers, spoonklink-tfArrows-monadLib, ... And then I worry that if spoonklink gets forked, Hackage will run out of disk space. :) Questions: Why are there so many monad transformer packages? Why is mtl [considered] uncool? What are the key differences? Most of these seemingly competing packages were written by Andy Gill and are maintained by Ross Paterson. Does this mean that these packages are not competing but rather work together in some way? And do Andy and Ross consider any of their own packages as obsolete? Which one should me and you use?

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• WCF - remote service without using IIS - base address?

  - by Mark Pim

  I'm trying to get my head around the addressing of WCF services. We have a client-server setup where the server occasionally (maybe once a day) needs to push data to each client. I want to have a lightweight WCF listener service on each client hosted in an NT service to receive that data. We already have such an NT service setup hosting some local WCF services for other tasks so the overhead of this is minimal. Because of existing legacy code on the server I believe the service needs to be exposed as ASMX and use basicHttpBinding to allow it to connect. Each client is registered on the server by the user (they need to configure them individually) so discovery is not the issue. My question is, how does the addressing work? I imagine the user entering the client's address on the server in the form http://0.0.0.0/MyService or even http://hostname/MyService If so, how do I configure the client service in its App.config? Do I use localhost? If not then what is the reccommended way of exposing the service to the server? Note: I don't want to host in IIS as that adds extra requirements to the hardware required for the client. The clients will be almost certainly located on LANs, not over the public internet

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• Jquery Livesearch with quicksilver plugin to include not just the <li>s

  - by 133794m3r

  Ok, what i'm trying to do here is to make the exact code found here here ordered list and make it so that it doesn't just not work when i try to add additional elements into the list. Also i'm planning on using the more effecient one linked to at the end but i cannot put it here so you'll have to find that link on your own sadly. Since i'm trying to use this for a knowledge base page i want to allow people to be able to search through the items on the page and go to the proper part(ie loading it into the viewing area) but it's not letting me even include a simple anchor in there. if there is anyway to do something similar or to edit it so that it'll include everything within the <li> that'd be great. I don't know if anyone out there has done something like this before, but if they have and wouldn't mind sharing the code with me i'd be extremely happy. If no one has but does know how to make it include everything within the <li> including text also a great thing to have. I imagine that i won't be the only person out there in this world with my exact query.

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• Project with multiple binaries in Eclipse CDT

  - by Robert Schneider

  I think it is quite normal to have more than one binary in a project. However, with Eclipse CDT I don't know how to set up the IDE to get things done. I know I can create several projects - one per binary. And I know I can set the dependencies per project. However, I cannot regard them as one project in Eclipse. If I'd like to share the code with a version control system (like svn), each developer has to import the projects separately. What I miss is something like the Solution (sln file) in Visual Studio. Should I create a single project and create the make files by myself? I haven't tried it out yet, but there is this 'project set' which can be ex- and imported. Is this the solution? Can this be put into version control? My goal it to put everything under version control, not only subprojects. I cannot imagine that CDT makes only sense for single-binary applications. How can I work properly?

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• What are the correct bindings for an NSComboBox for use with Core Data

  - by theMikeSwan

  Imagine if you will a Core Data app with two entities (Employee, and Department). Employees have a to-one relationship with department (department) and the inverse is a to-many relationship (employees). In the UI you can select individual Employee entities and edit the details in a detail area (there are of course other attributes and there is UI for adding and editing Department entities). When using a popup button the bindings are: content = PopUpArrayController.arrangedObjects content values = PopUpArrayController.arrangedObjects.name (name is an NSString) selected object = EmployeeArrayController.selection.department.name This allows for viewing of all departments in the popup menu, correct selection of the current Employee's department, and allows that department to be changed as expected. The goal is to change this for an NSComboBox so that the user can tab to the box and type the department name in without switching to the mouse. I have tried numerous different bindings to accomplish this. I even had it work for one run with these bindings: content = PopUpArrayController.arrangedObjects.name value = EmployeeArrayController.selection.department.name At least once this worked as expected (it even added a new department when the entered text did not match any existing department). Now however it will display the available Departments and auto complete but will not update the model with the correct value when the value is changed in the combo box. If the Department is set or changed with the popup the correct department is shown in the combo box. Does anyone know what I am missing? Thanks.

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• Mathematical annotations in a PDF file

  - by kvaruni

  I like to annotate papers I read in a digital way. Numerous programs exist to help in this process. For example, on OS X one can use programs such as Skim or even Preview. However, making annotations is dreadful when one wishes to add mathematical annotations, such as formulas or greek letters. A cumbersome "solution" is to select the desired symbol one by one using the Special Characters palette, though this considerably slows down the annotation process. Is there any way to add mathematical annotations to a PDF? The only two limitations that I would impose on a solution is that 1) the mathematical text needs to be selectable, i.e. it must be text and 2) I want to limit the number of programs I need to make the process as painless as possible. Some of the more promising solutions I have tried include generating LaTeX with LaTeXiT, but it seems to be impossible to add a PDF on top of another PDF. Another attempt was to use jsMath to generate the symbols and copy-paste these as annotation using one of the jsMath fonts. This results in unreadable, incorrect characters.

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• ai: Determining what tests to run to get most useful data

  - by Sai Emrys

  This is for http://cssfingerprint.com I have a system (see about page on site for details) where: I need to output a ranked list, with confidences, of categories that match a particular feature vector the binary feature vectors are a list of site IDs & whether this session detected a hit feature vectors are, for a given categorization, somewhat noisy (sites will decay out of history, and people will visit sites they don't normally visit) categories are a large, non-closed set (user IDs) my total feature space is approximately 50 million items (URLs) for any given test, I can only query approx. 0.2% of that space I can only make the decision of what to query, based on results so far, ~10-30 times, and must do so in <~100ms (though I can take much longer to do post-processing, relevant aggregation, etc) getting the AI's probability ranking of categories based on results so far is mildly expensive; ideally the decision will depend mostly on a few cheap sql queries I have training data that can say authoritatively that any two feature vectors are the same category but not that they are different (people sometimes forget their codes and use new ones, thereby making a new user id) I need an algorithm to determine what features (sites) are most likely to have a high ROI to query (i.e. to better discriminate between plausible-so-far categories [users], and to increase certainty that it's any given one). This needs to take into balance exploitation (test based on prior test data) and exploration (test stuff that's not been tested enough to find out how it performs). There's another question that deals with a priori ranking; this one is specifically about a posteriori ranking based on results gathered so far. Right now, I have little enough data that I can just always test everything that anyone else has ever gotten a hit for, but eventually that won't be the case, at which point this problem will need to be solved. I imagine that this is a fairly standard problem in AI - having a cheap heuristic for what expensive queries to make - but it wasn't covered in my AI class, so I don't actually know whether there's a standard answer. So, relevant reading that's not too math-heavy would be helpful, as well as suggestions for particular algorithms. What's a good way to approach this problem?

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• How do I Handle Ties When Ranking Results in MySQL?

  - by Laxmidi

  Hi, How does one handle ties when ranking results in a mysql query? I've simplified the table names and columns in this example, but it should illustrate my problem: SET @rank=0; SELECT student_names.students, @rank := @rank +1 AS rank, scores.grades FROM student_names LEFT JOIN scores ON student_names.students = scores.students ORDER BY scores.grades DESC So imagine the the above query produces: Students Rank Grades Al 1 90 Amy 2 90 George 3 78 Bob 4 73 Mary 5 NULL William 6 NULL Even though Al and Amy have the same grade, one is ranked higher than the other. Amy got ripped-off. How can I make it so that Amy and Al have the same ranking, so that they both have a rank of 1. Also, William and Mary didn't take the test. They bagged class and were smoking in the boy's room. They should be tied for last place. The correct ranking should be: Students Rank Grades Al 1 90 Amy 1 90 George 3 78 Bob 4 73 Mary 5 NULL William 5 NULL If anyone has any advice, please let me know. Thank you! -Laxmidi

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• Anyone got a nifty credit expiry algorithm?

  - by garethkeenan

  Our website uses a credit system to allow users to purchase inexpensive digital goods (eg. photos). We use credits, rather than asking the user to pay for items individually, because the items are cheap and we are trying to keep our credit-card/PayPal overhead low. Because we aren't a bank, we have to expire credits after a certain amount of time. We expire deposit credits after a year, but other types of credits (bonuses, prizes, refunds) may have a different shelf-life. When a buyer buys an item, we spend the credit that is going to expire first. Our current system keeps track of every deposit by storing the original value and the remainder to be spent. We keep a list of all purchases as well, of course. I am currently moving to a system which is much more like a traditional double-entry accounting system. A deposit will create a ledger item, increasing the user's 'spending' account balance. Every purchase will also create a ledger item, decreasing the user's 'spending' account balance. The new system has running balances, while the old system does not, which greatly improves our ability to find problems and do reconciliations. We do not want to use the old system of keeping a 'remainder' value attached to each deposit record because it is inefficient to replay a user's activities to calculate what the remainder of each deposit is over time (for the user's statement). So, after all of this verbose introduction, my question is "Does anyone else out there have a similar system of expiring credits?" If you could describe how you calculate expired credits it would be a great help. If all expired credits had the exact same shelf life, we would be able to calculate the expired amount using: Total Deposits - Total Spending - Deposits Not Due To Expire = Amount to Expire However, because deposits can have different shelf lives, this formula does not work because more than one deposit can be partially spent at any given time.

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• Subversion versus Vault

  - by WebDude

  I'm currently reviewing the benefits of moving from SVN to a SourceGear Vault. Has anyone got advice or a link to a detailed comparison between the two? Bear in mind I would have to move my current Source Control system across which works strongly in SVN's favor Here is some info I have found out thus far from my own investigations. I have been taking some time tests between the two and vault seems to perform most operations much faster. Time tests used the same server as the repository, the same workstation client, and the same project. Time Comparisons SVN Add/Commit    12:30 Get Latest Revision    5:35 Tagging/Labelling    0:01 Branching    N/A - I don't think true branching exists in SVN Vault Add/Commit    4:45 Get Latest Revision    0:51 Tagging/Labelling    0:30 Branching    3:23 (can't get this to format correctly) I also found an online source comparing some other points. This is the kind of information i'm looking for. Usage Comparisons Subversion is edit/merge/commit only. Vault allows you to do either edit/merge/commit or checkout/edit/checkin. Vault looks and acts just like VSS, which makes the learning curve effectively zero for VSS users. Vault has a VS plugin, but it only works if you're going to run in checkout-mode. Subversion has clients for pretty much every OS you can imagine; Vault has a GUI client for Windows and a command line client for Mono. Both will support remote work, since both use HTTP as their transport (Subversion uses extended DAV, Vault uses SOAP). Subversion installation, especially w/ Apache, is more complex. Subversion has a lot of third party support. Vault has just a few things. My question Has anyone got advice or a link to a detailed comparison between the two?

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• Pros and cons of making database IDs consistent and "readable"

  - by gmale

  Question Is it a good rule of thumb for database IDs to be "meaningless?" Conversely, are there significant benefits from having IDs structured in a way where they can be recognized at a glance? What are the pros and cons? Background I just had a debate with my coworkers about the consistency of the IDs in our database. We have a data-driven application that leverages spring so that we rarely ever have to change code. That means, if there's a problem, a data change is usually the solution. My argument was that by making IDs consistent and readable, we save ourselves significant time and headaches, long term. Once the IDs are set, they don't have to change often and if done right, future changes won't be difficult. My coworkers position was that IDs should never matter. Encoding information into the ID violates DB design policies and keeping them orderly requires extra work that, "we don't have time for." I can't find anything online to support either position. So I'm turning to all the gurus here at SA! Example Imagine this simplified list of database records representing food in a grocery store, the first set represents data that has meaning encoded in the IDs, while the second does not: ID's with meaning: Type 1 Fruit 2 Veggie Product 101 Apple 102 Banana 103 Orange 201 Lettuce 202 Onion 203 Carrot Location 41 Aisle four top shelf 42 Aisle four bottom shelf 51 Aisle five top shelf 52 Aisle five bottom shelf ProductLocation 10141 Apple on aisle four top shelf 10241 Banana on aisle four top shelf //just by reading the ids, it's easy to recongnize that these are both Fruit on Aisle 4 ID's without meaning: Type 1 Fruit 2 Veggie Product 1 Apple 2 Banana 3 Orange 4 Lettuce 5 Onion 6 Carrot Location 1 Aisle four top shelf 2 Aisle four bottom shelf 3 Aisle five top shelf 4 Aisle five bottom shelf ProductLocation 1 Apple on aisle four top shelf 2 Banana on aisle four top shelf //given the IDs, it's harder to see that these are both fruit on aisle 4 Summary What are the pros and cons of keeping IDs readable and consistent? Which approach do you generally prefer and why? Is there an accepted industry best-practice?

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• Access and modify attributes/objects which are not part of the form backing bean

  - by spa

  I use Spring MVC (via Spring Roo) to build a small web application for administering persons. In the page for creating a person the bean Person is used as form backing object (key "person" in the model map). <form:form action="${form_url}" method="POST" modelAttribute="person"> I would like to add some attributes to the model map which can be altered by the user in the creation form. Basically, I try to add a Boolean, so that I can control which page is displayed next after the user presses the submit button. I try to modify the Boolean (key "myBoolean" in the model map) using a simple checkbox: <form:checkbox id="_myboolean_id" path="myBoolean"/> However, as I am new to Spring MVC I have some difficulties here. The Boolean object is not an attribute of the form backing object. So if I try to access it the following exception is thrown (of course): Invalid property 'myBoolean' of bean class [de.cm.model.Person]: Bean property 'myBoolean' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter? Is there are way to access a value of the model map directly? The only solution I can imagine right now is a kind of wrapper object around the class Person and my additional attributes which is used as a new form backing object. However, this is more work for a IMHO simple task. Do you have a better solution?

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• How do I detect whether the sample supplied by VideoSink.OnSample() is right-side up?

  - by Ken Smith

  We're currently using the Silverlight VideoSink to capture video from users' local webcams, kinda like so: protected override void OnSample(long sampleTime, long frameDuration, byte[] sampleData) { if (FrameShouldBeSubmitted()) { byte[] resampledData = ResizeFrame(sampleData); mediaController.SetVideoFrame(resampledData); } } Now, on most of the machines that we've tested, the video sample provided in the byte[] sampleData parameter is upside-down, i.e., if you try to take the RGBA data and turn it into, say, a WriteableBitmap, the bitmap will be upside-down. That's odd, but fairly easy to correct, of course -- you just have to reverse the array as you encode it. The problem is that at least on some machines (e.g., the single Macintosh in our test environment), the video sample provided is no longer upside-down, but right-side up, and hence, flipping the image actually results in an image that's received upside-down on the far side. I reported this to MS as a bug, but their (terse) response was that it was "As Designed". Further attempts at clarification have so far been ignored. Now, I'll grant that it's kinda entertaining to imagine the discussions behind this design decision: "OK, just to make it interesting, let's play the video rightside up on a Mac, but let's turn it upside down for Windows!" "Great idea!" "Yeah, that'll keep those developers guessing!" But beyond that, I can't find this, umm, "feature" documented anywhere, nor can I find any documentation on how one is supposed to be able to tell that a given video sample is upside down or rightside up. Any thoughts on how to tell this?

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• Why would javascript click-areas not be working in IE8?

  - by Edward Tanguay

  I'm trying to find a bug in an old ASP.NET application which causes IE8 to not be able to click on the following "button" area in our application: <td width="150px" class="ctl00_CP1_UiCommandManager1i toolBarItem" valign="middle" onmouseout="onMouseOverCommand(this,1,'ctl00_CP1_UiCommandManager1',0,0);" onmouseover="onMouseOverCommand(this,0,'ctl00_CP1_UiCommandManager1',0,0);" onmousedown="onMouseDownCommand(this, 'ctl00_CP1_UiCommandManager1', 0, 0);" onmouseup="onMouseUpCommand(this, 'ctl00_CP1_UiCommandManager1', 0, 0);" id="ctl00_CP1_UiCommandManager1_0_0"> <span style="width:100%;overflow:hidden;text-overflow:ellipsis;vertical-align:middle;white-space:nowrap;"> NEW </span> </td> When we switch IE8 to IE7 compatibility mode, the problem disappears, IE7 is able to click on it. Since the above HTML is generated by a third party control (Janus, http://www.janusys.com/controls), we don't have the source code. has anyone experienced any similar problems with IE8? I've determined that it actually fires the onMouseDownCommand command also the CSS of the button area is different in IE8, it doesn't have color shading that it does in IE7. I can imagine that somewhere the HTML is not valid and IE8 being stricter is not playing along, but where? any advice on how to narrow in on this bug welcome ANSWER: Turned out to be that the application was not checking the navigator.agent for "MSIE 8.0" and was thus treating IE8 has a non-Internet-Explorer browser. Thanks Lazarus for the tip, the IE8 Javascript debugger is very nice, like a Firebug for IE, will be using it more!

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• Learning AES: the KeyBytes

  - by Tom Brito

  I got the following example from here: import java.security.Security; import javax.crypto.Cipher; import javax.crypto.spec.SecretKeySpec; public class MainClass { public static void main(String[] args) throws Exception { Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider()); byte[] input = "www.java2s.com".getBytes(); byte[] keyBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17 }; SecretKeySpec key = new SecretKeySpec(keyBytes, "AES"); Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC"); System.out.println(new String(input)); // encryption pass cipher.init(Cipher.ENCRYPT_MODE, key); byte[] cipherText = new byte[cipher.getOutputSize(input.length)]; int ctLength = cipher.update(input, 0, input.length, cipherText, 0); ctLength += cipher.doFinal(cipherText, ctLength); System.out.println(new String(cipherText)); System.out.println(ctLength); // decryption pass cipher.init(Cipher.DECRYPT_MODE, key); byte[] plainText = new byte[cipher.getOutputSize(ctLength)]; int ptLength = cipher.update(cipherText, 0, ctLength, plainText, 0); ptLength += cipher.doFinal(plainText, ptLength); System.out.println(new String(plainText)); System.out.println(ptLength); } } I imagine that the byte[] keyBytes should be random generated, so I gone to test the max size before do it. When adding one more byte 0x18 to the array, the exception raised: InvalidKeyException: Key length not 128/192/256 bits. But the original 18 bytes (from 0 to 17) are not multiple of nither 128, 192 or 256. I would like to understand the math here.. can anyone explain me? Thanks!

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