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• git crlf configuration in mixed environment

  - by Jonas Byström

  I'm running a mixed environment, and keep a central, bare repository where I pull and push most of my stuff. This centralized repository runs on Linux, and I check out to Windows XP/7, Mac and Linux. In all repositories I put the following line in my .git/config: [core] autocrlf = true I don't have the flag safecrlf=true anywhere. First time when I modify stuff on my one Windows machine (XP) there is no problem and when I look at the diff, it looks fine. But when I do the same on the other Windows machine (7), all lines are shown as changed but local line endings are \r\n as expected (when checked in a hex editor). The same applies to a MacOSX can. Sometimes I get the feeling that the different systems wrestle on line endings, but I can't be sure (I'm loosing track of all the times I change specific files). I didn't use to have the autocrlf set, but set the flag many months back. Could that be causing my current problems? Do I need to clone everything again to loose some old baggage? Or are there other things that needs configuring too? I tried git checkout -- . about a million times, but with no success.

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• How can I tackle 'profoundly found elsewhere' syndrome (inverse of NIH)?

  - by Alistair Knock

  How can I encourage colleagues to embrace small-scale innovation within our team(s), in order to get things done quicker and to encourage skills development? (the term 'profoundly found elsewhere' comes from Wikipedia, although it is scarcely used anywhere else apart from a reference to Proctor & Gamble) I've worked in both environments where there is a strong opposition to software which hasn't been developed in-house (usually because there's a large community of developers), and more recently (with far fewer central developers) where off-the-shelf products are far more favoured for the usual reasons: maintenance, total cost over product lifecycle, risk management and so on. I think the off the shelf argument works in the majority of cases for the majority of users, even though as a developer the product never quite does what I'd like it to do. However, in some cases there are clear gaps where the market isn't able to provide specifically what we would need, or at least it isn't able to without charging astronomical consultancy rates for a bespoke solution. These can be small web applications which provide a short-term solution to a particular need in one specific department, or could be larger developments that have the potential to serve a wider audience, both across the organisation and into external markets. The problem is that while development of these applications would be incredibly cheap in terms of developer hours, and delivered very quickly without the need for glacial consultation, the proposal usually falls flat because of risk: 'Who'll maintain the project tracker that hasn't had any maintenance for the past 7 years while you're on holiday for 2 weeks?' 'What if one of our systems changes and the connector breaks?' 'How can you guarantee it's secure/better/faster/cheaper/holier than Company X's?' With one developer behind these little projects, the answers are invariably: 'Nobody, but...' 'It will break, just like any other application would...' 'I, uh...' How can I better answer these questions and encourage people to take a little risk in order to stimulate creativity and fast-paced, short-lifecycle development instead of using that 6 months to consult about what tender process we might use?

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• Event feed implementation - will it scale?

  - by SlappyTheFish

  Situation: I am currently designing a feed system for a social website whereby each user has a feed of their friends' activities. I have two possible methods how to generate the feeds and I would like to ask which is best in terms of ability to scale. Events from all users are collected in one central database table, event_log. Users are paired as friends in the table friends. The RDBMS we are using is MySQL. Standard method: When a user requests their feed page, the system generates the feed by inner joining event_log with friends. The result is then cached and set to timeout after 5 minutes. Scaling is achieved by varying this timeout. Hypothesised method: A task runs in the background and for each new, unprocessed item in event_log, it creates entries in the database table user_feed pairing that event with all of the users who are friends with the user who initiated the event. One table row pairs one event with one user. The problems with the standard method are well known – what if a lot of people's caches expire at the same time? The solution also does not scale well – the brief is for feeds to update as close to real-time as possible The hypothesised solution in my eyes seems much better; all processing is done offline so no user waits for a page to generate and there are no joins so database tables can be sharded across physical machines. However, if a user has 100,000 friends and creates 20 events in one session, then that results in inserting 2,000,000 rows into the database. Question: The question boils down to two points: Is this worst-case scenario mentioned above problematic, i.e. does table size have an impact on MySQL performance and are there any issues with this mass inserting of data for each event? Is there anything else I have missed?

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• git rebase onto remote updates

  - by Blake Chambers

  I work with a small team that uses git for source cod management. Recently, we have been doing topic branches to keep track of features then merging them into master locally then pushing them to a central git repository on a remote server. This works great when no changes have been made in master: I create my topic branch, commit it, merge it into master, then push. Hooray. However, if someone has pushed to origin before i do, my commits are not fast-forward. Thus a merge commit ensues. This also happens when a topic branch needs to merge with master locally to ensure my changes work with the code as of now. So, we end up with merge commits everywhere and a git log rivaling a friendship bracelet. So, rebasing is the obvious choice. What I would like is to: create topic branches holding several commits checkout master and pull (fast-forward because i haven't committed to master) rebase topic branches onto the new head of master rebase topics against master(so the topics start at masters head), bringing master up to my topic head My way of doing this currently is listed below: git checkout master git rebase master topic_1 git rebase topic_1 topic_2 git checkout master git rebase topic_2 git branch -d topic_1 topic_2 Is there a faster way to do this?

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• Is A Web App Feasible For A Heavy Use Data Entry System?

  - by Rob

  Looking for opinions on this, we're working on a project that is essentially a data entry system for a production line. Heavy data input by users who normally work in Excel or other thick client data systems. We've been told (as a consequence) that we have to develop this as a thick client using .NET. Our argument was to develop as a web app, as it resolves a lot of issues and would be easier to write and maintain. Their argument against the web is that (supposedly) the web is not ready yet for a heavy duty data entry system, and that the web in a browser does not offer the speed, responsiveness, and fluid experience for the end-user that a thick client can (citing things such as drag and drop, rapid auto-entry and data navigation, etc.) Personally, I think that with good form design and JQuery/AJAX, a web app could do everything a thick client does just as well, and they just don't know what they're talking about. The irony is that a thick client has to go to a lot more effort to manage the deployment and connectivity back to the central data server than a web app would need to do, so in terms of speed I would expect a web app to be faster. What are the thoughts of those out there? Are there any technologies currently in production use that modern data entry systems are being developed as web apps in? Appreciate any feedback. Regards, Rob.

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• Why does Rails screw up timezones when I am editing a resource?

  - by DJTripleThreat

  Steps to produce this: prompt>rails test_app prompt>cd test_app prompt>script/generate scaffold date_test my_date:datetime prompt>rake db:migrate now edit your app/views/date_tests/edit.html.erb: <h1>Editing date_test</h1> <% form_for(@date_test) do |f| %> <%= f.error_messages %> <p> RIGHT!<br/> <%= text_field_tag @date_test, f.object.my_date %> </p> <p> WRONG!<br /> <%= f.text_field :my_date %> </p> <p> <%= f.submit 'Update' %> </p> <% end %> <%= link_to 'Show', @date_test %> | <%= link_to 'Back', date_tests_path %> now edit your config/environment.rb: #add this config.time_zone = 'Central Time (US & Canada)' This recreates the problem I am having in my actual app. The problem with my app is that I'm storing a date in a hidden field and rendering a "user friendly" version. Creating a resource works fine but as soon as I try to edit it the time changes (it adds the difference between my current time zone configuration and UTC). go to http://localhost:3000/date_tests/new and save the time then go to reedit it and you will have two different representations of the date/time one which will save incorrectly and the other that will.

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• View results of affine transform

  - by stckjp

  I am trying to find out the reason why when I apply affine transformations on an image in OpenCV, the result of it is not visible in the preview window, but the entire window is black.How can I find workaround for this problem so that I can always view my transformed image (the result of the affine transform) in the window no matter the applied transformation? Update: I think that this happens because all the transformations are calculated with respect to the origin of the coordinate system (top left corner of the image). While for rotation I can specify the center of the rotation, and I am able to view the result, when I perform scaling I am not able to control where the transformed image goes. Is it possible to somehow move the coordinate system to make the image fit in the window? Update2: I have an image which contains only ROI at some position in it (the rest of the image is black), and I need to apply a set of affine transforms on it. To make things simpler and to see the effect of each individual transform, I applied each transform one by one. What I noticed is that, whenever I move (translate) the image such that the center of the ROI is in the center of the coordinate system (top left corner of the view window), all the affine transforms perform correctly without moving. However, by translating the center of ROI at the center of the coordinate system, the upper and the left part of the ROI remain cut out of the current view window. If I move ROI's central point to another point in the view window (for example the window center), an affine transform of type: A=[a 0 0; 0 b 0] (A is 2x3 matrix, parameter of the warpAffine function) moves the image (ROI), outside of the view window (which doesn't happen if the ROI's center is in the top-left corner). How can I modify the affine transform so the image doesn't move out of its place (behaves the same way as when the ROI center is in the center of the coordinate system)?

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• Replacement for Hamachi for SVN access

  - by Piers

  My company has been using Hamachi to access our SVN repository for a number of years. We are a small yet widely distributed development team with each programmer in a different country working from home. The server is hosted by a non-techie in our central office. Hamachi is useful here since it has a GUI and supports remote management. This system worked well for a while, but recently I have moved to a country with poor internet speeds. Hamachi will no longer connect 99% of the time - instead I get a "Probing..." message that doesn't resolve. It's certain to be a latency issue, as the same laptop will connect without problems when I cross the border and connect using a different ISP with better speeds. So I really need to replace Hamachi with some other VPN/protocol that handles latency better. The techie managing the repository is not comfortable installing and configuring Apache or IIS, so it looks like HTTP is out. I tried to convince my boss to go for a web hosting company, but he doesn't trust a 3rd party with our source. Any other recommended options / experiences out there for accessing our SVN repos that would be as simple as Hamachi for setup; but be more tolerant of network latency issues?

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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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• Centralized Exception handling for Eclipse plug-in

  - by Svilen

  Hello, At first I thought this would be question often asked, however trying (and failing) to look up info on this proved me wrong. Is there a mechanism in Eclipse platform for centralized exception handling of exceptions? For example... You have plug-in project which connects to a DB and issues queries, results of which are used to populate some e.g. views. This is like the most common example ever. :) Queries are executed almost for any user action, from every UI control the plug-in provides. Most likely the DB Query API will have some specific to the DB SomeDBGeneralException declared as being thrown by it. That's OK, you can handle those according to whatever your software design is. But how about unchecked exceptions which are likely to occur, e.g. , when communication with DB suddenly breaks for some network related reason? What if in such case one would like to catch those exceptions in a central place and for example provide user friendly message to the user (rather than the low level communication protocol api messages) and even some possible actions the user could execute in order to deal with the specific problem? Thinking in Eclipse platform context, the question may be rephrased as "Is there an extension point like "org.eclipse.ExceptionHandler" which allows to declare exception handlers for specific (some kind of filtering support) exceptions giving a lot of flexibility with the actual handling?"

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• Where can a self-teacher learn general good programming habits and conventions?

  - by lucid

  A few mistakes and general childishness in early adulthood have left me in a situation where I work a menial job, with no possibility (in the near future) of attending school. I aspire to one day work in the programming field (gaming specifically), after proving myself on the indie end of things. I've gotten very confident in C++, java, and python, and I find I'm able to solve any problem I want either from previous experience, or from scouring the web for help. The solutions work, and with each attempt they become more readable, maintainable, and extensible. But this is because I'm learning from mistakes and bad programming and design habits I feel I might have avoided with actual schooling. General tips like: "if it's hard to read or getting long, or you're writing it twice, it should be in one or more functions." or "design all your classes before you start coding, so you don't have to rewrite classes later when you discover an unforeseen dependency" Is there a good book or website for learning general good programming practices and design habits? Also, naming and format conventions. I realize sometimes development houses have their own conventions, but things like "Classes in python usually have the first letter of each word capitalized". I'd like to be able to show some source code to a potential employer, and be prepared when for what's expected on a team. Is there some central database of naming and formatting conventions somewhere? Also, feel free to give any thoughts on whether or not the self-teach, garner some indie sales, use them as your resume' route is realistic

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• git rebse onto remote updates

  - by Blake Chambers

  I work with a small team that uses git for source cod management. Recently, we have been doing topic branches to keep track of features then merging them into master locally then pushing them to a central git repository on a remote server. This works great when no changes have been made in master: I create my topic branch, commit it, merge it into master, then push. Hooray. However, if someone has pushed to origin before i do, my commits are not fast-forward. Thus a merge commit ensues. This also happens when a topic branch needs to merge with master locally to ensure my changes work with the code as of now. So, we end up with merge commits everywhere and a git log rivaling a friendship bracelet. So, rebasing is the obvious choice. What I would like is to: create topic branches holding several commits checkout master and pull (fast-forward because i haven't committed to master) rebase topic branches onto the new head of master rebase topics against master(so the topics start at masters head), bringing master up to my topic head My way of doing this currently is listed below: git checkout master git rebase master topic_1 git rebase topic_1 topic_2 git checkout master git rebase topic_2 git branch -d topic_1 topic_2 Is there a faster way to do this?

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• Programmatically configure MATLAB

  - by Richie Cotton

  Since MathWorks release a new version of MATLAB every six months, it's a bit of hassle having to set up the latest version each time. What I'd like is an automatic way of configuring MATLAB, to save wasting time on administrative hassle. The sorts of things I usually do when I get a new version are: Add commonly used directories to the path. Create some toolbar shortcuts. Change some GUI preferences. The first task is easy to accomplish programmatically with addpath and savepath. The next two are not so simple. Details of shortcuts are stored in the file 'shortcuts.xml' in the folder given by prefdir. My best idea so far is to use one of the XML toolboxes in the MATLAB Central File Exchange to read in this file, add some shortcut details and write them back to file. This seems like quite a lot of effort, and that usually means I've missed an existing utility function. Is there an easier way of (programmatically) adding shortcuts? Changing the GUI preferences seems even trickier. preferences just opens the GUI preference editor (equivalent to File - Preferences); setpref doesn't seems to cover GUI options. The GUI preferences are stored in matlab.prf (again in prefdir); this time in traditional name=value config style. I could try overwriting values in this directly, but it isn't always clear what each line does, or how much the names differ between releases, or how broken MATLAB will be if this file contains dodgy values. I realise that this is a long shot, but are the contents of matlab.prf documented anywhere? Or is there a better way of configuring the GUI? For extra credit, how do you set up your copy of MATLAB? Are there any other tweaks I've missed, that it is possible to alter via a script?

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• How to get a unique WindowRef in a dockable Qt application on Mac

  - by Robin

  How do I get a unique WindowRef from a Qt application that includes docked windows on the Mac? My code boils down to: int main(int argc, char* argv[]) { QApplication* qtApp = new QApplication(argc, argv); MyQMainWindow mainwin; mainwin.show(); } class MyQMainWindow : public QMainWindow { //... QDockWidget* mDock; MyQWidget* mDrawArea; QStackedWidget* mCentralStack; }; MyQMainWindow::MyQMainWindow() { mDock = new QDockWidget(tr("Docked Widget"), this); mDock->setMaximumWidth(180); //... addDockWidget(Qt::RightDockWidgetArea, mDock); mDrawArea = new MyQWidget(this); mCentralStack = new QStackedWidget(); mCentralStack->addWidget(mDrawArea); // Other widgets added to stack in production code. setCentralWidget(mCentralStack); //... } (Apologies if the above isn't syntactically correct, it's just easier to illustrate than to describe.) I added the following temporary code at the end of the above constructor: HIViewRef view1 = (HIViewRef) mDrawArea->winId(); HIViewRef view2 = (HIViewRef) mDock->winId(); WindowRef win1 = HIViewGetWindow(view1); WindowRef win2 = HIViewGetWindow(view2); My problem is that view1 and view2 are different, but win1 and win2 are the same! I tried the following equivalent on Windows: HWND win1 = (HWND)(mCentralDrawArea->winId()); HWND win2 = (HWND)(mDock1->winId()); This time win1 and win2 are different. I need the window handle to pass on to a 3rd party SDK so that it can draw into the central area only. BTW, I appreciate that the winId() method comes with lots of portability warnings, but a substantial refactor is out of the question for me. The same goes for using Carbon instead of Cocoa. Thanks.

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• Accessing global variables of custom controls in ASP.NET

  - by CL4NCY

  Hi, I have built lots of custom asp.net controls which work really well separately but I want to somehow allow global access to all their variables from anywhere on the page. I have a central control called the ContentManager which I can use to store these variables. The problem I have is that all the controls are bound at different times so I only want the variables available after they're bound. For example I have many custom repeaters on the page which when bound I want to add a reference in the content manager so all their variables are then available to use. <Custom:ContentManager ID="cm" runat="server"/> <Custom:Repeater ID="r1" runat="server"/> <Custom:Repeater ID="r2" runat="server"/> <Custom:Repeater ID="r3" runat="server"/> Then I want a tag which can access all variables from any of these controls. <%= cm.controls["r1"].Items[0]["name"] %> The problem with this is that the variable isn't available until the repeater is bound so I might need to use events to push out the value to tags on the page like so: <Custom:Var ID="v1" control="r1" value="Items[0]["name"]" runat="server"/> Is this possible or can you recommend a better approach?

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• Design an Application That Stores and Processes Files

  - by phasetwenty

  I'm tasked with writing an application that acts as a central storage point for files (usually document formats) as provided by other applications. It also needs to take commands like "file 395 needs a copy in X format", at which point some work is offloaded to a 3rd party application. I'm having trouble coming up with a strategy for this. I'd like to keep the design as simple as possible, so I'd like to avoid big extra frameworks or techniques like threads for as long as it makes sense. The clients are expected to be web applications (for example, one is a django application that receives files from our customers; the others are not yet implemented). The platform it will be running on is likely going to be Python on Linux, unless I have a strong argument to use something else. In the beginning I thought I could fit the information I wanted to communicate in the filenames, and let my application parse the filename to figure out what it needed to do, but this is proving too inflexible with the amount of information I'm realizing I need to make available. Another idea is to pair FTP with a database used as a communication medium (client uploads a file and updates the database with a command as a row in a table) but I don't like this idea because adding commands (a known change) looks like it will require adding code as well as changing database schemas. It will also muddy up the interface my clients will have to use. I looked into Pyro to let applications communicate more directly but I don't like the idea of running an extra nameserver for this one purpose. I also don't see a good way to do file transfer within this framework. What I'm looking for is techniques and/or technologies applicable to my problem. At the simplest level, I need the ability to accept files and messages with them.

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• Table not created by Hibernate

  - by User1

  I annotated a bunch of POJO's so JPA can use them to create tables in Hibernate. It appears that all of the tables are created except one very central table called "Revision". The Revision class has an @Entity(name="RevisionT") annotation so it will be renamed to RevisionT so there is not a conflict with any reserved words in MySQL (the target database). I delete the entire database, recreate it and basically open and close a JPA session. All the tables seem to get recreated without a problem. Why would a single table be missing from the created schema? What instrumentation can be used to see what Hibernate is producing and which errors? Thanks. UPDATE: I tried to create as a Derby DB and it was successful. However, one of the fields has a a name of "index". I use @org.hibernate.annotations.IndexColumn to specify the name to something other than a reserved word. However, the column is always called "index" when it is created. Here's a sample of the suspect annotations. @ManyToOne @JoinColumn(name="MasterTopID") @IndexColumn(name="Cx3tHApe") protected MasterTop masterTop; Instead of creating MasterTop.Cx3tHApe as a field, it creates MasterTop.Index. Why is the name ignored?

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• New desktop GUI developer; can choose any platform...

  - by alexantd

  I'm planning a client-server product for a tiny, low-volume, high-cost vertical market. One of the components of the product will be a desktop application, simple to moderate in complexity, for data entry and uploading to a central server from remote PCs and/or Macs via SOAP. The server is a Java web app. Customers will be choosing their platform (Windows or Mac) based on what the client app runs on, so my options are wide-open here. However, I will be developing on a Mac and have a strong allergy to MS-specific technologies (sorry). The app will not need to run on any non-desktop-computer devices and I have total freedom to say it will support X but not Y or Z without any negative consequences (quite the luxury, to be sure). I have a lot of experience in server-side development but very little in desktop GUI stuff, and am evaluating my options on the client - basically what do I want to commit to learning over the next 6+ months. I have server-side Java experience as well as a brief dabble in iPhone development, which went OK. Overall I'm looking for: Ease of learning & development IDE support Healthy surrounding ecosystem (libraries, tools, help, etc.) Quality documentation My options as I see them, in rough order of how I'm currently mentally ranking them: Java Swing Cocoa Java SWT JavaFX Adobe AIR XULRunner Am I leaving anything out?

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• Publishing content to multiple (unknown) domains using Open Graph?

  - by Beau Lebens

  I'm working on an application that publishes content ('articles') on a variety of URLs, which are all controlled by the same WordPress installation (mapped domains, all powered by the same set of code/part of a network). All of the publishing is done through one central Facebook App. I have no idea what the domains for these URLS are going to be, since they are controlled by our users who register domains and then configure them within their account on our service. When I attempt to use Open Graph to publish content on one of these sites (that has a customized domain), they are rejected with the following error (error code 1611028): Object at URL * * * * of type 'article' is invalid because the domain '* * * ' is not allowed for the specified application id ' * * *'. You can verify your configured 'App Domain' at.... Since I can't enter all of the domains into Facebook, and since they are not derived from my App URL anyway, is there any way that I can have this work? Some sort of magic OG tag I can put in the pages or something? Or is it just not possible to do what I'm trying to do?

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• jQuery or CSS - How do you make a link in a table row appear underlined even when the cursor is in a

  - by adam

  I have a table of 3-4 columns, the central one being task names that are also links(yet another todo app..groan). Im trying to make it so that whenever the mouse hovers over any part of the table row - not just the link itself - the link will appear underlined. Its a small detail but its been annoying me like hell and i refuse to let it get the better of me now. At first i tried jQuery with a (forgive the obvious syntax errors but this is the jist) $('#row_in_question').hover( function(){ $(this).find(...the link..).toggleClass("highlighted") }, function(){ $(this).find(...the link..).toggleClass("highlighted") } ); with this as a styling for the a element in general .highlighted { text-decoration: underlined; } and it did indeed toggle the highlighted class on that link - however css inheritance got in the way and no visual changes made. Since i previously styled that link to have no underline when not hovered it wouldnt change the style. So how do i go about this? I dont want the whole row to become clickable, I just want the text to become underlined.

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• Log in to subdomain via main domain

  - by Mattias

  I have a website, available through multiple domainnames. like www.domain1.com .... www.domain5.com All my customers have their own subdomain. like: customer1.domain1.com customer2.domain1.com .... customer351.domain4.com Currently i dont use SSL, each customer log in their own account via their sub domain. I want to change this, and make all customers log in on a central log in page, that would use SSL, for example. https://login.domain1.com And somehow redirect each user to the correct sub domain adress. (Sub domain that don't use SSL) How do I do this, and maintain security? One idea i had: Login - add random value somewhere in the database, Redirect to subdomain, with querystring the randomvalue. And after that the session takes care of it, Each value can be used once only.. But how secure is that? I guess someone would ask the question "why?" to me. Because SSL costs money. And unfortunately i dont have a lot of it. :D Thanks for your time!

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• Creating collaborative whiteboard drawing application

  - by Steven Sproat

  I have my own drawing program in place, with a variety of "drawing tools" such as Pen, Eraser, Rectangle, Circle, Select, Text etc. It's made with Python and wxPython. Each tool mentioned above is a class, which all have polymorphic methods, such as left_down(), mouse_motion(), hit_test() etc. The program manages a list of all drawn shapes -- when a user has drawn a shape, it's added to the list. This is used to manage undo/redo operations too. So, I have a decent codebase that I can hook collaborative drawing into. Each shape could be changed to know its owner -- the user who drew it, and to only allow delete/move/rescale operations to be performed on shapes owned by one person. I'm just wondering the best way to develop this. One person in the "session" will have to act as the server, I have no money to offer free central servers. Somehow users will need a way to connect to servers, meaning some kind of "discover servers" browser...or something. How do I broadcast changes made to the application? Drawing in realtime and broadcasting a message on each mouse motion event would be costly in terms of performance and things get worse the more users there are at a given time. Any ideas are welcome, I'm not too sure where to begin with developing this (or even how to test it)

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• Database choices

  - by flobadob

  I have a prickly design issue regarding the choice of database technologies to use for a group of new applications. The final suite of applications would have the following database requirements... Central databases (more than one database) using mysql (myst be mysql due to justhost.com). An application to be written which accesses the multiple mysql databases on the web host. This application will also write to local serverless database (sqlite/firebird/vistadb/whatever). Different flavors of this application will be created for windows (.NET), windows mobile, android if possible, iphone if possible. So, the design task is to minimise the quantity of code to achieve this. This is going to be tricky since the languages used are already c# / java (android) and objc (iphone). Not too worried about that, but can the work required to implement the various database access layers be minimised? The serverless database will hold similar data to the mysql server, so some kind of inheritance in the DAL would be useful. Looking at hibernate/nhibernate and there is linq to whatever. So many choices!

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• Best method to search hierarchical data

  - by WDuffy

  I'm looking at building a facility which allows querying for data with hierarchical filtering. I have a few ideas how I'm going to go about it but was wondering if there are any recommendations or suggestions that might be more efficient. As an example imagine that a user is searching for a job. The job areas would be as follows. 1: Scotland 2: --- West Central 3: ------ Glasgow 4: ------ Etc 5: --- North East 6: ------ Ayrshire 7: ------ Etc A user can search specific (i.e. Glasgow) or in a larger area (i.e. Scotland). The two approaches I am considering are: keep a note of children in the database for each record (i.e. cat 1 would have 2, 3, 4 in its children field) and query against that record with a SELECT * FROM Jobs WHERE Category IN Areas.childrenField. Use a recursive function to find all results who have a relation to the selected area. The problems I see from both are: Holding this data in the db will mean having to keep track of all changes to structure. Recursion is slow and inefficent. Any ideas, suggestion or recommendations on the best approach? I'm using C# ASP.NET with MSSQL 2005 DB.

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• Inline function v. Macro in C -- What's the Overhead (Memory/Speed)?

  - by Jason R. Mick

  I searched Stack Overflow for the pros/cons of function-like macros v. inline functions. I found the following discussion: Pros and Cons of Different macro function / inline methods in C ...but it didn't answer my primary burning question. Namely, what is the overhead in c of using a macro function (with variables, possibly other function calls) v. an inline function, in terms of memory usage and execution speed? Are there any compiler-dependent differences in overhead? I have both icc and gcc at my disposal. My code snippet I'm modularizing is: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = AttractiveTerm * AttractiveTerm; EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); My reason for turning it into an inline function/macro is so I can drop it into a c file and then conditionally compile other similar, but slightly different functions/macros. e.g.: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = pow(SigmaSquared/RadialDistanceSquared,9); EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); (note the difference in the second line...) This function is a central one to my code and gets called thousands of times per step in my program and my program performs millions of steps. Thus I want to have the LEAST overhead possible, hence why I'm wasting time worrying about the overhead of inlining v. transforming the code into a macro. Based on the prior discussion I already realize other pros/cons (type independence and resulting errors from that) of macros... but what I want to know most, and don't currently know is the PERFORMANCE. I know some of you C veterans will have some great insight for me!!

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