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• SQL Server becomes slow after restart

  - by Tobi DM

  We use SQL Server 2005 on an Windwos Server 2008. Ther Server has 48 GB RAM. SQL Server is configured to use 40 GB RAM. There is only one database hosted (About 70 GB). The only app beside SQL Server is our App-Server which connects the clients to the database. Now we encounter the following problem: After a restart of the server our the performance is great. The server grabs the 40 GB RAM wich it is allowed to and then runs fast as hell. But after about 4 weeks the system becomes slower and slower. The execution of statements (seen in the profiler) is raising slowly. But I cannot see that there is something going wrong on the server. CPU usage is at about 20% I/O also seems to be no Problem The process monitor does also not show that there are strange apps or something like that. Eventlog does also have no interessting messages No open transactions or blockings to see We tried already the following things without effect: Droped the cache by using the statements DBCC FreeProcCache DBCC FREESYSTEMCACHE('ALL') DBCC DropCleanbuffers Restarted the Appserver we are using. Restart the sql server service But nothing did help exept restarting the whole server. Any ideas?

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• Python - Why use anything other than uuid4() for unique strings?

  - by orokusaki

  I see quit a few implementations of unique string generation for things like uploaded image names, session IDs, et al, and many of them employ the usage of hashes like SHA1, or others. I'm not questioning the legitimacy of using custom methods like this, but rather just the reason. If I want a unique string, I just say this: >>> import uuid >>> uuid.uuid4() 07033084-5cfd-4812-90a4-e4d24ffb6e3d And I'm done with it. I wasn't very trusting before I read up on uuid, so I did this: >>> import uuid >>> s = set() >>> for i in range(5000000): # That's 5 million! >>> s.add(uuid.uuid4()) ... ... >>> len(s) 5000000 Not one repeater (I didn't expect one considering the odds are like 1.108e+50, but it's comforting to see it in action). You could even half the odds by just making your string by combining 2 uuid4()s. So, with that said, why do people spend time on random() and other stuff for unique strings, etc? Is there an important security issue or other regarding uuid?

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• Passing data between ViewControllers versus doing local Fetch in each VC

  - by Tofrizer

  Hi All, I'm developing an iPhone app using Core Data and I'm looking for some general advice and recommendations on whether its acceptable to pass data between ViewControllers versus doing a local fetch in each ViewController as you navigate to it. Ordinarily I would say it all depends on various factors (e.g. performance etc) but the passing data approach is so prevalent in my app and I'm spooked by all the stories about Apple rejecting apps because of not conforming to their standard guidelines. So let me put another way -- is it non-standard to pass data between VC's? The reason I pass data so much is because each ViewController is just another view on to data present in my object model / graph. Once I have a handle on my first object in the first view controller (which I of course do have to fetch), I can use the existing object composition / relationships to drill down into the next level of detail into data and so I just pass these objects to the next VC. Separately, one possible downside with this passing-data-to-each-VC approach is I don't benefit from (what I perceive to be) the optimisation/benefits that NSFetchedResultsController provides in terms of efficient memory usage and section handling. My app is read-only but I do have one table with 5000 rows and I'm curious if I am missing out on NSFetchedResultsController benefits. Any thoughts on this as well? Can I somehow still benefit from NSFetchedResultsController goodness without having to do a full fetch (as I would have already passed in the data from my previous VC)? Thanks a lot.

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• Is there a significant mechanical difference between these faux simulations of default parameters?

  - by ccomet

  C#4.0 introduced a very fancy and useful thing by allowing default parameters in methods. But C#3.0 doesn't. So if I want to simulate "default parameters", I have to create two of that method, one with those arguments and one without those arguments. There are two ways I could do this. Version A - Call the other method public string CutBetween(string str, string left, string right, bool inclusive) { return str.CutAfter(left, inclusive).CutBefore(right, inclusive); } public string CutBetween(string str, string left, string right) { return CutBetween(str, left, right, false); } Version B - Copy the method body public string CutBetween(string str, string left, string right, bool inclusive) { return str.CutAfter(left, inclusive).CutBefore(right, inclusive); } public string CutBetween(string str, string left, string right) { return str.CutAfter(left, false).CutBefore(right, false); } Is there any real difference between these? This isn't a question about optimization or resource usage or anything (though part of it is my general goal of remaining consistent), I don't even think there is any significant effect in picking one method or the other, but I find it wiser to ask about these things than perchance faultily assume.

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• how can exec change the behavior of exec'ed program

  - by R Samuel Klatchko

  I am trying to track down a very odd crash. What is so odd about it is a workaround that someone discovered and which I cannot explain. The workaround is this small program which I'll refer to as 'runner': #include <stdio.h> #include <unistd.h> #include <string.h> #include <errno.h> int main(int argc, char *argv[]) { if (argc == 1) { fprintf(stderr, "Usage: %s prog [args ...]\n", argv[0]); return 1; } execvp(argv[1], argv + 1); fprintf(stderr, "execv failed: %s\n", strerror(errno)); // If exec returns because the program is not found or we // don't have the appropriate permission return 255; } As you can see, all this program does is use execvp to replace itself with a different program. The program crashes when it is directly invoked from the command line: /path/to/prog args # this crashes but works fine when it is indirectly invoked via my runner shim: /path/to/runner /path/to/prog args # works successfully For the life of me, I can figure out how having an extra exec can change the behavior of the program being run (as you can see the program does not change the environment). Some background on the crash. The crash itself is happening in the C++ runtime. Specifically, when the program does a throw, the crashing version incorrectly thinks there is no matching catch (although there is) and calls terminate. When I invoke the program via runner, the exception is properly caught. My question is any idea why the extra exec changes the behavior of the exec'ed program?

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• Do fluent interfaces significantly impact runtime performance of a .NET application?

  - by stakx

  I'm currently occupying myself with implementing a fluent interface for an existing technology, which would allow code similar to the following snippet: using (var directory = Open.Directory(@"path\to\some\directory")) { using (var file = Open.File("foobar.html").In(directory)) { // ... } } In order to implement such constructs, classes are needed that accumulate arguments and pass them on to other objects. For example, to implement the Open.File(...).In(...) construct, you would need two classes: // handles 'Open.XXX': public static class OpenPhrase { // handles 'Open.File(XXX)': public static OpenFilePhrase File(string filename) { return new OpenFilePhrase(filename); } // handles 'Open.Directory(XXX)': public static DirectoryObject Directory(string path) { // ... } } // handles 'Open.File(XXX).XXX': public class OpenFilePhrase { internal OpenFilePhrase(string filename) { _filename = filename } // handles 'Open.File(XXX).In(XXX): public FileObject In(DirectoryObject directory) { // ... } private readonly string _filename; } That is, the more constituent parts statements such as the initial examples have, the more objects need to be created for passing on arguments to subsequent objects in the chain until the actual statement can finally execute. Question: I am interested in some opinions: Does a fluent interface which is implemented using the above technique significantly impact the runtime performance of an application that uses it? With runtime performance, I refer to both speed and memory usage aspects. Bear in mind that a potentially large number of temporary, argument-saving objects would have to be created for only very brief timespans, which I assume may put a certain pressure on the garbage collector. If you think there is significant performance impact, do you know of a better way to implement fluent interfaces?

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• Why doesn't this jQuery snippet work in IE8 like it does in Firefox or Chrome (Live Demo Included) ?

  - by Siracuse

  I asked for help earlier on Stackoverflow involving highlighting spans with the same Class when a mouse hovers over any Span with that same Class. It is working great: http://stackoverflow.com/questions/2709686/how-can-i-add-a-border-to-all-the-elements-that-share-a-class-when-the-mouse-has $('span[class]').hover( function() { $('.' + $(this).attr('class')).css('background-color','green'); }, function() { $('.' + $(this).attr('class')).css('background-color','yellow'); } ) Here is an example of it in usage: http://dl.dropbox.com/u/638285/0utput.html However, it doesn't appear to work properly in IE8, while it DOES work in Chrome/Firefox. Here is a screenshot of it in IE8, with my mouse hovered over the " min) { min" section in the middle. As you can see, it highlighted the span that the mouse is hovering over perfectly fine. However, it has also highlighted some random spans above and below it that don't have the same class! Only the span's with the same Class as the one where the mouse is over should be highlighted green. In this screenshot, only that middle green section should be green. Here is a screenshot of it working properly in Firefox/Chrome with my mouse in the exact same position: This screenshot is correct as the span that the mouse is over (the green section) is the only one in this section that shares that class. Why is IE8 randomly green-highlighting spans when it shouldn't be (they don't share the same class) using my little jQuery snippet? Again, if you want to see it live I have it here: http://dl.dropbox.com/u/638285/0utput.html

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• javascript plugin - singleton pattern?

  - by Adam Kiss

  intro Hello, I'm trying to develop some plugin or/*and* object in javascript, which will control some properties over some object. It will also use jQuery, to ease development. idea This is in pseudocode to give you an idea, since I can't really describe it in english with the right words, it's impossible to go and use google to find out what I want to use (and learn). I will have plugin (maybe object?) with some variables and methods: plugin hideshow(startupconfig){ var c, //collection add: function(what){ c += what; }, do: function(){ c.show().hide().stop(); //example code } } and I will use it this way (or sort-of): var p = new Plugin(); p .add($('p#simple')) .add($('p#simple2')) .do(); note I'm not really looking for jQuery plugin tutorials - it's more like usage of singleton pattern in document in javascript, jQuery is mentione only because it will be used to modify dom and simplify selectors, jQuery plugin maybe just for that one little function add. I'm looking for something, that will sit on top of my document and call functions from itselft based on timer, or user actions, or whatever. problems I don't really know where to start with construction of this object/plugin I'm not really sure how to maintain one variable, which is collection of jQuery objects (something like $('#simple, #simple2');) I would maybe like to extedn jQuery with $.fn.addToPlugin to use chaining of objects, but that should be simple (really just each( p.add($(this)); )) I hope I make any sense, ideas, links or advices appreciated.

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• Javascript force GC collection? / Forcefully free object?

  - by plash

  I have a js function for playing any given sound using the Audio interface (creating a new instance for every call). This works quite well, until about the 32nd call (sometimes less). This issue is directly related to the release of the Audio instance. I know this because I've allowed time for the GC in Chromium to run and it will allow me to play another 32 or so sounds again. Here's an example of what I'm doing: <html><head> <script language="javascript"> function playSound(url) { snd = new Audio(url); snd.play(); delete snd; snd = null; } </script> </head> <body> <a href="#" onclick="playSound('blah.mp3');">Play sound</a> </body></html> I also have this, which works well for pages that have less than 32 playSound calls: var AudioPlayer = { cache: {}, play: function(url) { if (!AudioPlayer.cache[url]) AudioPlayer.cache[url] = new Audio(url); AudioPlayer.cache[url].play(); } }; But this will not work for what I want to do (dynamically replace a div with other content (from separate files), which have even more sounds on them - 1. memory usage would easily skyrocket, 2. many sounds will never play). I need a way to release the sound immediately. Is it possible to do this? I have found no free/close/unload method for the Audio interface. The pages will be viewed locally, so the constant loading of sounds is not a big factor at all (and most sounds are rather short).

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• Which view will be resolved, code from spring's docs

  - by Blankman

  So when you go to /appointments the get() action is called, so then would the view be get.jsp (assuming you are using .jsp, and assuming you are mapping action names to views)? And what about the getnewform? It seems to be returning an object? Is that basically passed into the view? @Controller @RequestMapping("/appointments") public class AppointmentsController { private final AppointmentBook appointmentBook; @Autowired public AppointmentsController(AppointmentBook appointmentBook) { this.appointmentBook = appointmentBook; } @RequestMapping(method = RequestMethod.GET) public Map<String, Appointment> get() { return appointmentBook.getAppointmentsForToday(); } @RequestMapping(value="/{day}", method = RequestMethod.GET) public Map<String, Appointment> getForDay(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date day, Model model) { return appointmentBook.getAppointmentsForDay(day); } @RequestMapping(value="/new", method = RequestMethod.GET) public AppointmentForm getNewForm() { return new AppointmentForm(); } @RequestMapping(method = RequestMethod.POST) public String add(@Valid AppointmentForm appointment, BindingResult result) { if (result.hasErrors()) { return "appointments/new"; } appointmentBook.addAppointment(appointment); return "redirect:/appointments"; } } In the example, the @RequestMapping is used in a number of places. The first usage is on the type (class) level, which indicates that all handling methods on this controller are relative to the /appointments path. The get() method has a further @RequestMapping refinement: it only accepts GET requests, meaning that an HTTP GET for /appointments invokes this method. The post() has a similar refinement, and the getNewForm() combines the definition of HTTP method and path into one, so that GET requests for appointments/new are handled by that method.

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• Handling form from different view and passing form validation through session in django

  - by Mo J. Mughrabi

  I have a requirement here to build a comment-like app in my django project, the app has a view to receive a submitted form process it and return the errors to where ever it came from. I finally managed to get it to work, but I have doubt for the way am using it might be wrong since am passing the entire validated form in the session. below is the code comment/templatetags/comment.py @register.inclusion_tag('comment/form.html', takes_context=True) def comment_form(context, model, object_id, next): """ comment_form() is responsible for rendering the comment form """ # clear sessions from variable incase it was found content_type = ContentType.objects.get_for_model(model) try: request = context['request'] if request.session.get('comment_form', False): form = CommentForm(request.session['comment_form']) form.fields['content_type'].initial = 15 form.fields['object_id'].initial = 2 form.fields['next'].initial = next else: form = CommentForm(initial={ 'content_type' : content_type.id, 'object_id' : object_id, 'next' : next }) except Exception as e: logging.error(str(e)) form = None return { 'form' : form } comment/view.py def save_comment(request): """ save_comment: """ if request.method == 'POST': # clear sessions from variable incase it was found if request.session.get('comment_form', False): del request.session['comment_form'] form = CommentForm(request.POST) if form.is_valid(): obj = form.save(commit=False) if request.user.is_authenticated(): obj.created_by = request.user obj.save() messages.info(request, _('Your comment has been posted.')) return redirect(form.data.get('next')) else: request.session['comment_form'] = request.POST return redirect(form.data.get('next')) else: raise Http404 the usage is by loading the template tag and firing {% comment_form article article.id article.get_absolute_url %} my doubt is if am doing the correct approach or not by passing the validated form to the session. Would that be a problem? security risk? performance issues? Please advise Update In response to Pol question. The reason why I went with this approach is because comment form is handled in a separate app. In my scenario, I render objects such as article and all I do is invoke the templatetag to render the form. What would be an alternative approach for my case? You also shared with me the django comment app, which am aware of but the client am working with requires a lot of complex work to be done in the comment app thats why am working on a new one.

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• Database for Python Twisted

  - by Will

  There's an API for Twisted apps to talk to a database in a scalable way: twisted.enterprise.dbapi The confusing thing is, which database to pick? The database will have a Twisted app that is mostly making inserts and updates and relatively few selects, and then other strictly-read-only clients that are accessing the database directly making selects. (The read-only users are not necessarily selecting the data that the Twisted app is inserting; its not as though the database is being used as a message-queue) My understanding - which I'd like corrected/adviced - is that: Postgres is a great DB, but all the Python bindings - and there is a confusing maze of them - are abandonware There is psycopg2, but that makes a lot of noise about doing its own connection-pooling and things; does this co-exist gracefully/usefully/transparently with the Twisted async database connection pooling and such? SQLLite is a great database for little things but if used in a multi-user way it does whole-database locking, so performance would suck in the usage pattern I envisage MySQL - after the Oracle takeover, who'd want to adopt it now or adopt a fork? Is there anything else out there?

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• Sending an email with browser capabilities and screen size etc.

  - by talkingnews

  A lot of my visitors are blind (with it being a site for the blind), and often when trying to diagnose problems, I'd like to know what version of browser etc they're using, whether flash is installed. Because more often than not, someone will swear they are using X, when in fact Y is installed. Currently, I'm using http://jsbrwsniff.sourceforge.net/usage.html piped into an email, but I've got 2 problems here: First of all, jsbrwsniff is quite "heavy" and hasn't been updated since early 2007, so there's a lot of -1's in the result. Secondly, if I call it as follows, the page reloads: <a href="#" onclick="sendEmail()">Email feedback</a> And if I call it like this, the page goes blank and looks like it's trying to infinitely load a blank page: <a href="javascript:sendEmail()">Email feedback</a> See the nightmare for yourself here: http://kingston.talking-newspapers.co.uk/ Now, I know there are 1001 articles and comments here and elsewhere saying "don't use browser sniffers, they can be spoofed (etc)", but honestly, you'll have to trust me that this is a significantly useful tool when you're talking someone in their more "senior years" and using a screenreader through "help about", when they've clicked the wrong window to start with! I'm using jquery anyway in the site, and I'm aware of $jQuery.browser and $jQuery.support, but these don't tell me the elements I need (like whether Flash is installed, and what version etc). I've looked everywhere for a jquery plugin for my needs, with no luck. Finally, if I have to stick to the current method of jsbrwsniff then it's not the end of the world, but if anyone knows a way of launching the user's email client populated with the information I need but WITHOUT refreshing or blanking the page, I'd love to know. BTW - there's a good reason for not using a webform, which is simply because it's easier for the screen-reader user to use an email client they are used to. Thanks!

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• Why does Perl's DBI complain about "failed: ERROR OCIEnvNlsCreate" when I try to connect to Oracle 1

  - by John

  I am getting the following error connecting to an Oracle 11g database using a simple Perl script: failed: ERROR OCIEnvNlsCreate. Check ORACLE_HOME (Linux) env var or PATH (Windows) and or NLS settings, permissions, etc. at The script is as follows: #!/usr/local/bin/perl use strict; use DBI; if ($#ARGV < 3) { print "Usage: perl testDbAccess.pl dataBaseUser dataBasePassword SID dataBasePort\n"; exit 0; } my ($user, $pwd, $sid, $port) = @ARGV; my $host = `hostname`; my $dbh; my $sth; my $dbname = "dbi:Oracle:HOST=$host;SID=$sid;PORT=$port"; openDbConnection(); closeDbConnection(); sub openDbConnection() { $dbh = DBI->connect ($dbname, $user ,$pwd , { RaiseError => 1}) || die "Database connection not made: $DBI::errstr"; } sub closeDbConnection() { #$sth->finish(); $dbh->disconnect(); } Anyone seen this problem before?

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• Copy Small Bitmaps on to Large Bitmap with Transparency Blend: What is faster than graphics.DrawImag

  - by Glenn

  I have identified this call as a bottleneck in a high pressure function. graphics.DrawImage(smallBitmap, x , y); Is there a faster way to blend small semi transparent bitmaps into a larger semi transparent one? Example Usage: XY[] locations = GetLocs(); Bitmap[] bitmaps = GetBmps(); //small images sizes vary approx 30px x 30px using (Bitmap large = new Bitmap(500, 500, PixelFormat.Format32bppPArgb)) using (Graphics largeGraphics = Graphics.FromImage(large)) { for(var i=0; i < largeNumber; i++) { //this is the bottleneck largeGraphics.DrawImage(bitmaps[i], locations[i].x , locations[i].y); } } var done = new MemoryStream(); large.Save(done, ImageFormat.Png); done.Position = 0; return (done); The DrawImage calls take a small 32bppPArgb bitmaps and copies them into a larger bitmap at locations that vary and the small bitmaps might only partially overlap the larger bitmaps visible area. Both images have semi transparent contents that get blended by DrawImage in a way that is important to the output. I've done some testing with BitBlt but not seen significant speed improvement and the alpha blending didn't come out the same in my tests. I'm open to just about any method including a better call to bitblt or unsafe c# code.

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• Can it be done in a more elegant way with the Swing Timer?

  - by Roman

  Bellow is the code for the simplest GUI countdown. Can the same be done in a shorter and more elegant way with the usage of the Swing timer? import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.SwingUtilities; public class CountdownNew { static JLabel label; // Method which defines the appearance of the window. public static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. public static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText("You have " + i + " seconds."); } } ); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); counter.start(); } }); } }

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• Use .bat file to recursively loop through folders and get hold of .class files

  - by user320550

  HI all, This is what i'm trying to do. I have a .bat file which takes in a argument which is nothing but a folder name. What i do first is go one level up (cd ..). Now in this directory i have 3 folders and each folders have sub-folders and have .class files in them. What i want to do is recursively loop through the folders and get hold of the .class files. Once this is done i want to echo the target folder of the .class file as well as echo the name of the.class file. So c:\temp\potter\myclass.class. I would echo out c:\temp\potter\ and myclass. I'm able to do this by writing a separate bat file which works. But when i integrate this with the recursive function it seems to break. This is what i'm doing: :: call the junit classes... and save the results echo step 3... cd %1 cd .. for /r %%a in (*.class) do set Var=%%a echo Full file location %Var% for %%i in ("%Var%") do Set CF=%%~dpi Set CF=%CF:~0,-1% :LOOP If "%CF:~-1,1%"=="\" GoTo :DONE Set CF=%CF:~0,-1% GoTo :LOOP :DONE Set CF=%CF:~0,-1% echo Folder Location %CF% ::cd %CF% For %%j in ("%Var%") Do Set name=%%~nxj :: -6 because of Quotations Set name=%name:~0,-6% echo File Name %name% echo step 3 complete... However i only get the output of one directory, while i have multiple directories having .class files. This is the output i get: step 3... Full file location C:\NKCV\Project\MyActivities\6_Selenium\htmlTestCasesConve rted2JUnit\iexplore\flow2\testCase_app2.class Folder Location C:\NKCV\Project\MyActivities\6_Selenium\htmlTestCasesConverte d2JUnit\iexplore\flow2 File Name testCase_app2 step 3 complete... missing argument! usage htmltestCaseLocation for eg., "C:\NKCV\Project\MyActivities\6_Selenium\htmlTestCases" Could anyone please let me know whats wrong here? Thanks.

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• AnyCPU/x86/x64 for C# application and it's C++/CLI dependency

  - by Soonts

  I'm Windows developer, I'm using Microsoft visual studio 2008 SP1. My developer machine is 64 bit. The software I'm currently working on is managed .exe written in C#. Unfortunately, I was unable to solve the whole problem solely in C#. That's why I also developed a small managed DLL in C++/CLI. Both projects are in the same solution. My C# .exe build target is "Any CPU". When my C++ DLL build target is "x86", the DLL is not loaded. As far as I understood when I googled, the reason is C++/CLI language, unlike other .NET languages, compiles to the native code, not managed code. I switched the C++ DLL build target to x64, and everything works now. However, AFAIK everything will stop working as soon as my client will install my product on a 32-bit OS. I have to support Windows Vista and 7, both 32 and 64 bit versions of each of them. I don't want to fall back to 32 bits. That 250 lines of C++ code in my DLL is only 2% of my codebase. And that DLL is only used in several places, so in the typical usage scenario it's not even loaded. My DLL implements two COM objects with ATL, so I can't use "/clr:safe" project setting. Is there way to configure the solution and the projects so that C# project builds "Any CPU" version, the C++ project builds both 32 bit and 64 bit versions, then in the runtime when the managed .EXE is starting up, it uses either 32-bit DLL or 64-bit DLL depending on the OS? Or maybe there's some better solution I'm not aware of? Thanks in advance!

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• Are document-oriented databases any more suitable than relational ones for persisting objects?

  - by Owen Fraser-Green

  In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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• How to bundle extension methods requiring configuration in a library

  - by Greg

  Hi, I would like to develop a library that I can re-use to add various methods involved in navigating/searching through a graph (nodes/relationships, or if you like vertexs/edges). The generic requirements would be: There are existing classes in the main project that already implement the equivalent of the graph class (which contains the lists of nodes / relationships), node class and relationship class (which links nodes together) - the main project likely already has persistence mechanisms for the info (e.g. these classes might be built using Entity Framework for persistance) Methods would need to be added to each of these 3 classes: (a) graph class - methods like "search all nodes", (b) node class - methods such as "find all children to depth i", c) relationship class - methods like "return relationship type", "get parent node", "get child node". I assume there would be a need to inform the library with the extending methods the class names for the graph/node/relationships table (as different project might use different names). To some extent it would need to be like how a generics collection works (where you pass the classes to the collection so it knows what they are). Need to be a way to inform the library of which node property to use for equality checks perhaps (e.g. if it were a graph of webpages the equality field to use might be the URI path) I'm assuming that using abstract base classes wouldn't really work as this would tie usage down to have to use the same persistence approach, and same class names etc. Whereas really I want to be able to, for a project that has "graph-like" characteristics, the ability to add graph searching/walking methods to it.

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• Docs for auto-generated methods in Ruby on Rails

  - by macek

  Rails has all sorts of auto-generated methods that I've often times struggled to find documentation for. For example, in routes.rb, if I have: map.resources :projects do |p| p.resources :tasks end This will get a plethora of auto-generate path and url helpers. Where can I find documentation for how to work with these paths? I generally understand how to work with them, but more explicit docs might help me understand some of the magic that happens behind the scenes. # compare project_path(@project) project_task_path(@project, @task) # to project_path(:id => @project.id) project_task_path(:project_id => @project.id, :id => @task.id) Also, when I change an attribute on a model, @post.foo_changed? will be true. Where can I find documentation for this and all other magical methods that are created like this? If the magic is there, I'd love to take advantage of it. And finally: Is there a complete resource for config.___ statements for environment.rb? I was able to find docs for Configuration#gem but what attributes can I set within the stubs like config.active_record.___, config.action_mailer.___, config.action_controller.___, etc. Again, I'm looking for a complete resource here, not just a settings for the examples I provided. Even if you can only answer one of these questions, please chime in. These things seem to have been hiding from me and it's my goal to get them some more exposure, so I'll be upvoting all links to docs that point me to what I'm looking for. Thanks! ps, If they're not called auto-generated methods, I apologize. Someone can teach me a lesson here, too :) Edit I'm not looking for tutorials here, folks. I have a fair amount of experience with rails; I'm just looking for complete docs. E.g., I understand how routing works, I just want docs where I can read about all of the usage options.

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• Failure remediation strategy for File I/O

  - by Brett

  I'm doing buffered IO into a file, both read and write. I'm using fopen(), fseeko(), standard ANSI C file I/O functions. In all cases, I'm writing to a standard local file on a disk. How often do these file I/O operations fail, and what should the strategy be for failures? I'm not exactly looking for stats, but I'm looking for a general purpose statement on how far I should go to handle error conditions. For instance, I think everyone recognizes that malloc() could and probably will fail someday on some user's machine and the developer should check for a NULL being returned, but there is no great remediation strategy since it probably means the system is out of memory. At least, this seems to be the approach taken with malloc() on desktop systems, embedded systems are different. Likewise, is it worth reattempting a file I/O operation, or should I just consider a failure to be basically unrecoverable, etc. I would appreciate some code samples demonstrating proper usage, or a library guide reference that indicates how this is to be handled. Any other data is, of course, welcome.

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• Native functions throw UnsatisfiedLinkError in custom view, despite working in main activity

  - by Mark Ingram

  For some reason I can only call native functions from my main activity and not any custom views that I've created. Here is an example file (I followed a tutorial, but renamed the classes http://mindtherobot.com/blog/452/android-beginners-ndk-setup-step-by-step/) See the usage of the native function "getNewString". package com.example.native; import android.app.Activity; import android.app.AlertDialog; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.os.Bundle; import android.view.View; public class NativeTestActivity extends Activity { static { System.loadLibrary("nativeTest"); } private native String getNewString(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(new BitmapView(this)); String hello = getNewString(); // This line works fine new AlertDialog.Builder(this).setMessage(hello).show(); } } class BitmapView extends View { static { System.loadLibrary("nativeTest"); } private native String getNewString(); public BitmapView(Context context) { super(context); String hello = getNewString(); // This line throws the UnsatisfiedLinkError new AlertDialog.Builder(this.getContext()).setMessage(hello).show(); } } How can I call native functions in my custom views? I've built the application as an Android 2.2 app. I'm running the application on my HTC Desire. I have the latest SDK (9) and latest NDK (r5).

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• Null Pointer Exception in Primavera P6 8.1

  - by gwrichard

  I am getting a null pointer exception in a Primavera P6 8.1 installation. The exception only occurs in one section of the web-client: Application settings.P6 web and the P6 API are deployed on the same WebLogic (10.3.5) node running on a Windows Server 2008 R2 installation. I have done this installation using this same software stack a dozen times and don't have this issue on any of the other installs. Exact error below: Match: beginTraversal Match: digest selected JREDesc: JREDesc[version 1.6.0_20+, heap=-1--1, args=null, href=http://java.sun.com/products/autodl/j2se, sel=false, null, null], JREInfo: JREInfo for index 0: platform is: 1.7 product is: 1.7.0_17 location is: http://java.sun.com/products/autodl/j2se path is: C:\Program Files (x86)\Java\jre7\bin\javaw.exe args is: null native platform is: Windows, x86 [ x86, 32bit ] JavaFX runtime is: JavaFX 2.2.7 found at C:\Program Files (x86)\Java\jre7\ enabled is: true registered is: true system is: true Match: ignoring maxHeap: -1 Match: ignoring InitHeap: -1 Match: digesting vmargs: null Match: digested vmargs: [JVMParameters: isSecure: true, args: ] Match: JVM args after accumulation: [JVMParameters: isSecure: true, args: ] Match: digest LaunchDesc: http://localhost:7001/p6/action/jnlp/appletsjnlp.jnlp?mainClass=com.primavera.pvapplets.adminpreferences.AdminPreferencesApplet&classPath=adminpreferences.jar,prm-applets-common.jar,forms-1.0.7.jar,prm-guisupport.jar,prm-to.jar,jide.jar,tablesupport.jar,formsupport.jar,applets-bo.jar,commons-lang.jar,prm-common.jar,resource_strings.jar,prm-img.jar,commons-logging.jar&name=AdminPreferences&version=8.1.2.0.0602 Match: digest properties: [] Match: JVM args: [JVMParameters: isSecure: true, args: ] Match: endTraversal .. Match: JVM args final: Match: Running JREInfo Version match: 1.7.0.17 == 1.7.0.17 Match: Running JVM args match: have:<> satisfy want:<> Java Plug-in 10.17.2.02 Using JRE version 1.7.0_17-b02 Java HotSpot(TM) Client VM User home directory = C:\Users\gwrichard ---------------------------------------------------- c: clear console window f: finalize objects on finalization queue g: garbage collect h: display this help message l: dump classloader list m: print memory usage o: trigger logging q: hide console r: reload policy configuration s: dump system and deployment properties t: dump thread list v: dump thread stack x: clear classloader cache 0-5: set trace level to <n> ----------------------------------------------------

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• Special technology needed for browser based chat?

  - by orokusaki

  On this post, I read about the usage of XMPP. Is this sort of thing necessary, and more importantly, my main question expanded: Can a chat server and client be built efficiently using only standard HTTP and browser technologies (such as PHP and JS, or RoR and JS, etc)? Or, is it best to stick with old protocols like XMPP find a way to integrate them with my application? I looked into CampFire via LiveHTTPHeaders and Firebug for about 5 minutes, and it appears to use Ajax to send a request which is never answered until another chat happens. Is this just CampFire opening a new thread on the server to listen for an update and then returning a response to the request when the thread hears an update? I noticed that they're requesting on a specific port (8043 if memory serves me) which makes me think that they're doing something more complex than just what I mentioned. Also, the URL requested started with /tcp/ which I found interesting. Note: I don't expect to ever have more than 150 users live-chatting in all the rooms combined at the same time. I understand that if I was building a hosted pay for chat service like CampFire with thousands of concurrent users, it would behoove me to invest time in researching special technologies vs trying to reinvent the wheel in a simple way in my app. Also, if you're going to do it with server polling, how often would you personally poll to maximize response without slamming the server?

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