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  • Best way to do interprocess communication on Mac OS X

    - by jbrennan
    I'm looking at building a Cocoa application on the Mac with a back-end daemon process (really just a mostly-headless Cocoa app, probably), along with 0 or more "client" applications running locally (although if possible I'd like to support remote clients as well; the remote clients would only ever be other Macs or iPhone OS devices). The data being communicated will be fairly trivial, mostly just text and commands (which I guess can be represented as text anyway), and maybe the occasional small file (an image possibly). I've looked at a few methods for doing this but I'm not sure which is "best" for the task at hand. Things I've considered: Reading and writing to a file (…yes), very basic but not very scalable. Pure sockets (I have no experience with sockets but I seem to think I can use them to send data locally and over a network. Though it seems cumbersome if doing everything in Cocoa Distributed Objects: seems rather inelegant for a task like this NSConnection: I can't really figure out what this class even does, but I've read of it in some IPC search results I'm sure there are things I'm missing, but I was surprised to find a lack of resources on this topic.

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  • Can you overlay transparent images in Blackberry Apps?

    - by Greg
    I have a very simple application that has one screen and one button. The main screen has a verticalFieldManager with a BitmapField inside it, and one button beneath the bitmap. I want to be able to overlay another image on top of this when the user clicks a button. The overlay image is a PNG with transparent background, and this is important for design, so I can't use popupscreen or a new screen because the backgrounds are always white by default, and I've heard alpha doesn't really do the trick. I guess what I'm asking is if anyone knows a simple way to... A) take a standard verticalFieldManager and overlay a PNG on top of the inner contents B) overlay a PNG over the screen, no matter the contents The basic functionality of this app was intended to be - show an image. on click, show another overlaid on top. on click again, remove the popup image. I haven't found anything that addresses something like this online, but I have read of people doing similar things that utilize popupscreen and new screens in a way I don't need to do. Hopefully this makes sense. Thanks

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  • Beyond core java

    - by Paul
    Coming to the end of the first year of my CS degree, we've done some Java but just the core stuff; manipulating strings and arrays, inheritance, implementing logic etc. I visit this website daily and I see so much stuff that is beyond me; using frameworks; managing databases etc. It makes me feel like I've just learned the syntax of Java, and there is so much more to do with it. My question is though, how do I get there? I don't think I'm advanced enough to join an open source project, which seems to be suggested often (though I'd love to) and I've looked at other similar questions on here (like this one) but even then I don't think that'd work for me.. firstly, could somebody try give me some commonly used frameworks etc and how and what they are used for? Where would be a good place to start? How did you get started in using the things you do? Or perhaps you think I'm going down the wrong route. Should I learn another language, and just wait until the moment occurs where it's clear what I should be doing? I'm only in the first year of my degree, so far we've lightly covered Haskell and Java, and I've done a little HTML and CSS in my free time. I know that next year we cover python, so perhaps I should just wait till then and see if I prefer that? I feel like I also risk learning something in depth and then never using it... I suppose I'm also asking for personal experiences; was there a point where you felt you'd exceeded the basic grasp of a language (does not necessarily have to be Java related) and reach a more "advanced" level? I guess I'll put subjective tag on this, but really I just want to know how to get beyond the basic understanding of a language.

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  • h:commandButton action not working inside a h:datatable.

    - by Chris
    I'm stuck with this piece of jsf code that I don't understand why it's working when used outside a datatable and doesn't inside a datatable... <h:dataTable id="myTable" rendered="true" value="#{bean.selectedItemsList}" var="items"> <h:column> <h:commandButton action="#{bean.removeItemFromList}" image="/resources/images/deleterow.gif"> <f:actionListener binding="#{bean.actionListenerImpl}" type="com.mycorp.ActionListenerImpl"/> </h:commandButton> </h:column> <h:column> <h:outputText value="#{items}" /> </h:column> </h:dataTable> I read around the net to put value="#{items}" inside the action listener so the action can get the items in the row like this: <f:actionListener value="#{items}" binding="#{bean.actionListenerImpl}" type="com.mycorp.ActionListenerImpl"/> But it's doesn't work either. Bu if I do the action outside the data table everything work fine. <h:commandButton action="#{bean.removeItemFromList}" image="/resources/images/deleterow.gif"> <f:actionListener binding="#{bean.actionListenerImpl}" type="com.mycorp.ActionListenerImpl"/> </h:commandButton> Side note I also tried a4j:commandButton and didn't so I guess my problem is probably the actionlistener or how the bean handling it.

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  • Resetting a PChar variable

    - by scott-thornton
    Hi, I don't know much about delphi win 32 programming, but I hope someone can answer my question. I get duplicate l_sGetUniqueIdBuffer saved into the database which I want to avoid. The l_sGetUniqueIdBuffer is actually different ( the value of l_sAuthorisationContent is xml, and I can see a different value generated by the call to getUniqueId) between rows. This problem is intermittant ( duplicates are rare...) There is only milliseconds difference between the update date between the rows. Given: ( unnesseary code cut out) l_sGetUniqueIdBuffer: PChar; FOutputBufferSize : integer; FOutputBufferSize := 1024; while( not dmAccomClaim.ADOQuClaimIdentification.Eof ) do begin // Get a unique id for the request l_sGetUniqueIdBuffer := AllocMem (FOutputBufferSize); l_returnCode := getUniqueId (m_APISessionId^, l_sGetUniqueIdBuffer, FOutputBufferSize); dmAccomClaim.ADOQuAddContent.Active := False; dmAccomClaim.ADOQuAddContent.Parameters.ParamByName('pContent').Value := (WideString(l_sAuthorisationContent)); dmAccomClaim.ADOQuAddContent.Parameters.ParamByName('pClaimId').Value := dmAccomClaim.ADOQuClaimIdentification.FieldByName('SB_CLAIM_ID').AsString; dmAccomClaim.ADOQuAddContent.Parameters.ParamByName('pUniqueId').Value := string(l_sGetUniqueIdBuffer); dmAccomClaim.ADOQuAddContent.ExecSQL; FreeMem( l_sAuthorisationContent, l_iAuthoriseContentSize ); FreeMem( l_sGetUniqueIdBuffer, FOutputBufferSize ); end; I guess i need to know, is the value in l_sGetUniqueIdBuffer being reset for every row??

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  • Delphi Unicode String Type Stored Directly at its Address (or "Unicode ShortString")

    - by Andreas Rejbrand
    I want a string type that is Unicode and that stores the string directly at the adress of the variable, as is the case of the (Ansi-only) ShortString type. I mean, if I declare a S: ShortString and let S := 'My String', then, at @S, I will find the length of the string (as one byte, so the string cannot contain more than 255 characters) followed by the ANSI-encoded string itself. What I would like is a Unicode variant of this. That is, I want a string type such that, at @S, I will find a unsigned 32-bit integer (or a single byte would be enough, actually) containing the length of the string in bytes (or in characters, which is half the number of bytes) followed by the Unicode representation of the string. I have tried WideString, UnicodeString, and RawByteString, but they all appear only to store an adress at @S, and the actual string somewhere else (I guess this has do do with reference counting and such). Update: The most important reason for this is probably that it would be very problematic if sizeof(string) were variable. I suspect that there is no built-in type to use, and that I have to come up with my own way of storing text the way I want (which actually is fun). Am I right? Update I will, among other things, need to use these strings in packed records. I also need manually to read/write these strings to files/the heap. I could live with fixed-size strings, such as <= 128 characters, and I could redesign the problem so it will work with null-terminated strings. But PChar will not work, for sizeof(PChar) = 1 - it's merely an address. The approach I eventually settled for was to use a static array of bytes. I will post my implementation as a solution later today.

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  • OOP 101 - quick question.

    - by R Bennett
    I've used procedural for sometime now and trying to get a better understanding of OOP in Php. Starting at square 1 and I have a quick question ot get this to gel. Many of the basic examples show static values ( $bob-name = "Robert";) when assigning a value, but I want to pass values... say from a form ( $name = $_POST['name']; ) class Person { // define properties public $name; public $weight; public $age; public function title() { echo $this->name . " has submitted a request "; } } $bob = new Person; // want to plug the value in here $bob->name = $name; $bob->title(); I guess I'm getting a little hung up in some areas as far as accessing variables from within the class, encapsulation & "rules", etc., can $name = $_POST['name']; reside anywhere outside of the class or am I missing an important point? Thanks

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  • Reuse, Rewrite, or Refactor?

    - by Jon Purdy
    At work I inherited development of a PHP-based Web site after the consultant who originally produced it bailed out and left without a trace. Literally half of the code is ripped from online tutorials, and there are thousands of lines of cruft that, being incomplete, do precious little. Hardly any of it actually works. I've been trying to pull out the usable components, such as the layout (cleverly intermixed with code), session management (delicately seasoned with unescaped, unvalidated SQL queries), and a few other things, but it's very difficult to force all of this junk into place. Further, I don't speak idiomatic PHP, being more of a Perl user, and I'm supposed to be on this project principally for maintenance, so rewriting everything seems like it would take just as long as wrestling the existing monster back into place. As an aside, I have literally never seen anything as badly written as this. Welcome me to the world of working with other people's code, I guess, but I do hope it's not this common in the real world to have such gems as these: // WHY IS THIS NOT WORKING // I know this is bad but were going for working stuff right now... // This is a PHP code outputing Javascript code outputting HTML...do not go further // Not userful I'm looking for the best advice I can get here. What would you do if you were in my position?

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  • How to make UISlider output nice rounded numbers exponentially?

    - by RickiG
    Hi I am implementing a UISlider a user can manipulate to set a distance. I have never used the CocoaTouch UISlider, but have used other frameworks sliders, usually there is a variable for setting the "step" and other "helper" properties. The documentation for the UISlider deals only with a max and min value, and the output is always a 6 decimal float with a linear relation to the position of the "slider nob". I guess I will have to implement the desired functionality step by step. To the user, the min/max values range from 10 m to 999 Km, I am trying to implement this in an exponential way, that will feel natural to the user. I.e. the user experiences a feeling of control over the values, big or small. Also that the "output" has reasonable values. Values like 10m 200m 2.5km 150 km etc. instead of 1.2342356 m or 108.93837756 km. I would like for the step size to increase by 10m for the first 200m, then maybe by 50m up to 500m, then when passing the 1000 m value, it starts to deal with Kilometers, so then it is step size = 1 km up until 50 km, then maybe 25 km steps etc. Any way I go about this I end up doing a lot of rounding and a lot of calculations wrapped in a forrest of if statements and NSString/Number conversions, each time the user moves the slider just a little. I was hoping someone could lend me a bit of inspiration/math help or make me aware of a more lean approach to solving this problem. My last idea is to populate and array with a 100 string values, then have the slider int value correspond to a string, this is not very flexible, but doable. Thank you in advance for any help given:)

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  • Adding Css class to all <input type'text'> elements? Javascript / Css?

    - by Kohan
    I want to apply a CSS class to every textbox in my site: <div class="editor-label"> <label for="FoodType">FoodType</label> </div> <div class="editor-field"> <input id="HelpText" name="FoodType" type="text" value="" /> </div> <p> <input type="submit" value="Create" /> </p> And I thought, Hey! Easy. I'll add a jquery function to find them all in the masterpage. <script type="text/javascript"> $(document).ready(function(){ $('input').addClass('textbox'); } </script> Unfortunately this will also select the submit button. How can i only select input elements that have a text type attribute? Alternativly is this possible using entirely CSS? If both these methods are not possible, i guess i will just have to manually add the class to every textbox i make? Cheers, Kohan.

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  • wpf error template - red box still visible on collapse of an expander

    - by Andy Clarke
    Hi, I'm doing some validation on the DataSource of TextBox that's within an Expander and have found that once a validation error has been triggered, if I collapse the Expander, the red box stays where the TextBox would have been. <Expander Header="Blah Blah Blah"> <TextBox Name="TextBox" Validation.ErrorTemplate="{DynamicResource TextBoxErrorTemplate}" Text="{Binding Path=Blah, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" /> </Expander> I've tried to get round this by binding the visibility of the Error Template to the Expander, however I think there's something wrong with the binding. <local:NotVisibleConverter x:Key="NotVisibleConverter" /> <ControlTemplate x:Key="TextBoxErrorTemplate"> <DockPanel> <Border BorderBrush="Red" BorderThickness="2" Visibility="{Binding Path=IsExpanded, Converter={StaticResource NotVisibleConverter}, RelativeSource={RelativeSource AncestorType=Expander}}" > <AdornedElementPlaceholder Name="MyAdorner" /> </Border> </DockPanel> <ControlTemplate.Triggers> <Trigger Property="Validation.HasError" Value="true"> <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}"/> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> I guess I've gone wrong with my binding, can someone put me back on track please? Alternatively does anyone know another solution to the ErrorTemplate still being visible on the collapse of an Expander?

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  • python VTE Terminal weirdness

    - by mykhal
    i'm trying to use the terminal from python VTE binding (python-vte from debian squeeze) as a virtual terminal emulator (just for ANSI/control chars text processing) in interactive python console, everything looks (almost) all right: >>> import vte >>> term = vte.Terminal() >>> term.feed("a\nb") >>> print repr(term.get_text(lambda *a: True).rstrip()) 'a\n b' however, launching this code (little modified) as python script, different result is yielded: $ python vte_wiredness_1.py '' strangely enough, pasting the code back into the (new) interactive python session also yields empty string: >>> import vte >>> term = vte.Terminal() >>> term.feed("a\nb") >>> print repr(term.get_text(lambda *a: True).rstrip()) '' >>> first thing caming on my mind was that the only difference between the two cases is the timing - there had to be some delay before get_text. unfortunately, preluding get_text with some seconds sleep did not help then i thought it has something to do with X window environment. but the results are the same pure linux console (with some warning on missing graphics). i wonder what causes such an unpredictable behavior (interactive console - pasted vs typed, and it's not the delay.. ant the interactive console has nothing to do with the vte terminal object.. i guess) can someone explain what is happening? is it possible to use the VTE Term such way? that the "b" letter in the output is preceded by the space, is another strangeness (all consecutive lines are preceded by more spaces.. looks like I have to send carriage return before the string.) (the lambda *a: True get_text method argument i'm using is a dummy callback, it's is some SlotSelectedCallback.. for its explanation i'd be grateful as well :) )

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  • .Net Entity objectcontext thread error

    - by Chris Klepeis
    I have an n-layered asp.net application which returns an object from my DAL to the BAL like so: public IEnumerable<SourceKey> Get(SourceKey sk) { var query = from SourceKey in _dataContext.SourceKeys select SourceKey; if (sk.sourceKey1 != null) { query = from SourceKey in query where SourceKey.sourceKey1 == sk.sourceKey1 select SourceKey; } return query.AsEnumerable(); } This result passes through my business layer and hits the UI layer to display to the end users. I do not lazy load to prevent query execution in other layers of my application. I created another function in my DAL to delete objects: public void Delete(SourceKey sk) { try { _dataContext.DeleteObject(sk); _dataContext.SaveChanges(); } catch (Exception ex) { Debug.WriteLine(ex.Message + " " + ex.StackTrace + " " + ex.InnerException); } } When I try to call "Delete" after calling the "Get" function, I receive this error: New transaction is not allowed because there are other threads running in the session This is an ASP.Net app. My DAL contains an entity data model. The class in which I have the above functions share the same _dataContext, which is instantiated in my constructor. My guess is that the reader is still open from the "Get" function and was not closed. How can I close it?

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  • Polymorphic Queue

    - by metdos
    Hello Everyone, I'm trying to implement a Polymorphic Queue. Here is my trial: QQueue <Request *> requests; while(...) { QString line = QString::fromUtf8(client->readLine()).trimmed(); if(...)){ Request *request=new Request(); request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); //this initialize variables in request using tcpMessage if(request->requestType==REQUEST_LOGIN){ LoginRequest loginRequest; request=&loginRequest; request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); requests.enqueue(request); } //Here pointers in "requests" do not point to objects I created above, and I noticed that their destructors are also called. LoginRequest *loginRequest2=dynamic_cast<LoginRequest *>(requests.dequeue()); loginRequest2->decodeFromTcpMessage(); } } Unfortunately, I could not manage to make work Polymorphic Queue with this code because of the reason I mentioned in second comment.I guess, I need to use smart-pointers, but how? I'm open to any improvement of my code or a new implementation of polymorphic queue. Thanks.

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  • populate textboxs with xml node attributes

    - by Doug
    I have Data.xml: <?xml version="1.0" encoding="utf-8" ?> <data> <album> <slide title="Autum Leaves" description="Leaves from the fall of 1986" source="images/Autumn Leaves.jpg" thumbnail="images/Autumn Leaves_thumb.jpg" /> <slide title="Creek" description="Creek in Alaska" source="images/Creek.jpg" thumbnail="images/Creek_thumb.jpg" /> </album> </data> I'd like to be able to edit the attributes of each Slide node via GridView (that has a "Select" column added.) And so far I have: protected void GridView1_SelectedIndexChanged(object sender, EventArgs e) { int selectedIndex = GridView1.SelectedIndex; LoadXmlData(selectedIndex); } private void LoadXmlData(int selectedIndex) { XmlDocument xmldoc = new XmlDocument(); xmldoc.Load(MapPath(@"..\photo_gallery\Data.xml")); XmlNodeList nodelist = xmldoc.DocumentElement.ChildNodes; XmlNode xmlnode = nodelist.Item(selectedIndex); titleTextBox.Text = xmlnode.Attributes["title"].InnerText; descriptionTextBox.Text = xmlnode.Attributes["description"].InnerText; sourceTextBox.Text = xmlnode.Attributes["source"].InnerText; thumbTextBox.Text = xmlnode.Attributes["thumbnail"].InnerText; The code for LoadXmlData is just a guess on my part - I'm new to working with xml in this way. I'd like have the user to slected the row from the gridview, then populate a set of text boxes with each slide attributed for updating back to the Data.xml file. The error I'm getting is "Object reference not set to an instance of an object" at the line: titleTextBox.Text = xmlnode.Attributes["@title"].InnerText; - so I'm not reaching the attribute "title" of the slide node. Thanks for any ideas you may have.

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  • My perl script is acting funny...

    - by TheGNUGuy
    I am trying to make a jabber bot from scratch and my script is acting funny. I was originally developing the bot on a remote CentOS box, but I have switched to a local Win7 machine. Right now I'm using ActiveState Perl and I'm using Eclipse with the perl plugin to run a debug the script. The funny behavior I'm experiencing occurs when I run or debug the script. If I run the script using the debugger it works fine, meaning I can send messages to the bot and it can send messages to me. However when I just execute the script normally the bot sends the successful connection message then it disconnects from my jabber server and the script ends. I'm a novice when it comes to perl and I can't figure out what I'm doing wrong. My guess is it has something to do with the subroutines and sending the presence of the bot. (I know for sure that it has something to do with sending the bot's presence because if the presence code is removed, the script behaves as expected except the bot doesn't appear to be online.) If anyone can help me with this that would be great. I originally had everything in 1 file but separated them into several trying to figure out my problem here are the pastebin links to my source code. jabberBot.pl: http://pastebin.com/cVifv0mm chatRoutine.pm: http://pastebin.com/JXmMT7av trimSpaces.pm: http://pastebin.com/SkeuWtu1 Thanks again for any help!

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  • What is the best way to save the environment from before an alarm handler goes off when the alarm do

    - by EpsilonVector
    I'm trying to implement user threads on a 2.4 Linux kernel (homework) and the trick for context switch seems to be using an alarm that goes off every x milliseconds and sends us to an alarm handler from which we can longjmp to the next thread. What I'm having difficulties with is figuring out how to save the environment to return to later. Basically I have an array of jmp_buffs, and every time a "context switch" using the alarm happens I want to save the previous context to the appropriate entry of the array and longjmp to the next one. However, just the fact that I need to do this from the event handler means that just using setjmp in the event handler won't give me exactly the kind of environment I want (as far as stack and program counter are involved) because the stack has the event handler call in it and the pc is in the event handler. I suppose I can look at the stack and alter it to fit my needs, but that feels a bit cumbersome. Another idea I had is to somehow pass the environment before the jump to event handler as a parameter to the event handler, but I can't figure out if this is possible. So I guess my question is- how do I do this right?

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  • Partial Classes - are they bad design?

    - by dferraro
    Hello, I'm wondering why the 'partial class' concept even exists in .NET. I'm working on an application and we are reading a (actually very good) book relavant to the development platform we are implementing at work. In the book he provides a large code base /wrapper around the platform API and explains how he developed it as he teaches different topics about the platform development. Anyway, long story short - he uses partial classes, all over the place, as a way to fake multiple inheritence in C# (IMO). Why he didnt just split the classes up into multiple ones and use composition is beyond me. He will have 3 'partial class' files to make up his base class, each w/ 3-500 lines of code... And does this several times in his API. Do you find this justifiable? If it were me, I'd have followed the S.R.P. and created multiple classes to handle different required behaviors, then create a base class that has instances of these classes as members (e.g. composition). Why did MS even put partial class into the framework?? They removed the ability to expand/collapse all code at each scope level in C# (this was allowed in C++) because it was obviously just allowing bad habits - partial class is IMO the same thing. I guess my quetion is: Can you explain to me when there would be a legitimate reason to ever use a partial class? I do not mean this to be a rant / war thread. I'm honeslty looking to learn something here. Thanks

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  • What MS technology to use for HTTP service returning XML?

    - by Borek
    I need to create a service that: accepts HTTP requests (with query string or HTTP POST parameters) does some processing on the requests (checking if the request is valid, authentication etc.) reads data from a custom store (another HTTP call in our case) returns the result as custom XML (defined with XSD) I'm trying to think of various MS technologies that could help me and how good they would be for this scenario (pretty standard one I guess). The tasks above are relatively separate, this is what comes to mind: HTTP front-end: ASP.NET Web Forms ASP.NET MVC (seems more appropriate here as I won't need server controls, view state etc.) WCF? Don't know much about it or how well it would suit my task. Custom logic on the server: this will probably be a generic C# code in all cases (sometimes "plugged into" or called from MVC controllers or some equivalent place in other technologies) Reading data from internal data stores: As said, this is another HTTP server in our case. Options that come to mind: Just read the data using something like WebClient (Just theoretically) implement a LINQ provider (Just even more theoretically) implement an EF provider Output the data as custom XML: Linq2XML Serialization? Is it flexible enough? Does WCF provide some tools for this? Some "OXM" - Object/XML mapper if there is something like that for .NET I may be wrong in many of my assumptions, this is just a quick list that comes to mind after a quick research. Some general notes / questions: Testing is important Solution with a clear domain model would be much preferred over the one without Can Entity Framework actually help somewhere in my scenario? If so, where and how? Would WCF be an appropriate technology for this? I don't know much about it.

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  • Problem with load testing Web Service - VSTS 2008

    - by Carlos
    Hello, I have a webtest with makes a simple call to a WebService which looks like that: MyWebService webService = new MyWebService(); webService.Timeout = 180000; webService.myMethod(); I am not using ThinkTimes, also the Run Duration is set to 5 minutes. When I ran this test simulating only 1 user, I check the counters and I found something like that: Tests Total: 4500 Network Interface\Bytes sent (agent machine): 35,500 Then I ran the same tests, but this time simulating 2 users and I got something like that: Tests Total: 2225 Network Interface\Bytes sent (agent machine): 30,500 So when I increased the numbers of users the tests/sec was half than when I use only 1 user and the bytes sent by the agent was also lower. I think it is strange, because it doesn't seems I have a bottleneck in my agent machine since CPU is never higher than 30% and I have over 1.5GB of RAM free, also my network utilization is like 0.5% of its capacity. In order to troubleshot this I ran a test using Step Pattern, the simulated users went from 20 to 800 users. When I check the requests/sec it is practically constant through the whole test, so it is clear there is something in my test or my environment which is preventing the number of requests from gets higher. It would be a expected behavior if the "response time" was getting higher because it would tell me the requests wasn't been processed properly, but the strange thing is the response time is practically constant all the time and it is pretty low actually. I have no idea why my agent can't send more requests when I increase the numbers of users, any help/tip/guess would be really appreciate.

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  • Binding type variables that only occur in assertions

    - by Giuseppe Maggiore
    Hi! I find it extremely difficult to describe my problem, so here goes nothing: I have a bunch of assertions on the type of a function. These assertions rely on a type variable that is not used for any parameter of the function, but is only used for internal bindings. Whenever I use this function it does not compile because, of course, the compiler has no information from which to guess what type to bind my type variable. Here is the code: {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, UndecidableInstances, FlexibleContexts, EmptyDataDecls, ScopedTypeVariables, TypeOperators, TypeSynonymInstances #-} class C a a' where convert :: a -> a' class F a b where apply :: a -> b class S s a where select :: s -> a data CInt = CInt Int instance S (Int,String) Int where select (i,_) = i instance F Int CInt where apply = CInt f :: forall s a b . (S s a, F a b) => s -> b f s = let v = select s :: a y = apply v :: b in y x :: Int x = f (10,"Pippo") And here is the generated error: FunctorsProblems.hs:21:4: No instances for (F a Int, S (t, [Char]) a) arising from a use of `f' at FunctorsProblems.hs:21:4-17 Possible fix: add an instance declaration for (F a Int, S (t, [Char]) a) In the expression: f (10, "Pippo") In the definition of `x': x = f (10, "Pippo") Failed, modules loaded: none. Prelude>

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  • How to access and run field events from extension js?

    - by Dan Roberts
    I have an extension that helps in submitting forms automatically for a process at work. We are running into a problem with dual select boxes where one option is selected and then that selection changes another field's options. Since setting an option selected property to true doesn't trigger the field's onchange event I am trying to do so through code. The problem I've run into is that if I try to access or run functions on the field object from the extension, I get the error Error: uncaught exception: [Exception... "Component is not available" nsresult: "0x80040111 (NS_ERROR_NOT_AVAILABLE)" location: "JS frame :: chrome://webformsidebar/content/webformsidebar.js :: WebFormSidebar_FillProcess :: line 499" data: no] the line causing the error is... if (typeof thisField.onchange === 'function') The line right before it works just fine... thisField.options[t].selected=true; ...so I'm not sure why this is resulting in such an error. What surprises me most I guess is that checking for the existence of the function leads to an error. It feels like the problem is related to the code running in the context of the extension instead of the browser window document. If so, is there any way to call a function in the browser window context instead? Do I need to actually inject code into the page somehow? Any other ideas? Thanks

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  • Can any linux API or tool watch for any change in any folder below e.g. /SharedRoot or do I have to

    - by Simon B.
    I have a folder with ~10 000 subfolders. Can any linux API or tool watch for any change in any folder below e.g. /SharedRoot or do I have to setup inotify for each folder? (i.e. I loose if I want to do this for 10k+ folders). I guess yes, since I've already seen examples of this inefficient method, for instance http://twistedmatrix.com/trac/browser/trunk/twisted/internet/inotify.py?rev=28866#L345 My problem: I need to keep folders time-sorted with most recently active "project" up top. When a file changes, each folder above that file should update its last-modified timestamp to match the file. Delays are ok. Opening a file (typically MS Excel) and closing again, its file date can jump up and then down again. For this reason I need to wait until after a file is closed, then queue the folder of that file for checking, and only a while later do I go and look for the newest file in its folder, since the filedate of the triggering file could already be back-dated to its original timestamp by Excel or similar programs. Also in case several files from same folder are used/created, it makes sense to buffer timestamping of that folders' parents to at least get a bunch of updates collapsed into one delayed update. I'm looking for a linux solution. I have some code that can be run on a windows server, most of the queing functionality is here: http://github.com/sesam/FolderdateFollowsFiles/blob/master/FolderdateFollowsFiles/Follower.vb Available API:s The relative of inotify on windows, ReadDirectoryChangesW, can watch a folder and its whole subtree; see bWatchSubtree on http://msdn.microsoft.com/en-us/library/aa365465(VS.85).aspx Samba? Patching samba source is a possibility, but perhaps there are already hooks available? Other possibilities, like client side (various windows versions) and spying on file activities in order to update folders recursively?

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  • Truncating long strings with CSS: feasible yet?

    - by Sam Stokes
    Is there any good way of truncating text with plain HTML and CSS, so that dynamic content can fit in a fixed-width-and-height layout? I've been truncating server-side by logical width (i.e. a blindly-guessed number of characters), but since a 'w' is wider than an 'i' this tends to be suboptimal, and also requires me to re-guess (and keep tweaking) the number of characters for every fixed width. Ideally the truncation would happen in the browser, which knows the physical width of the rendered text. I've found that IE has a text-overflow: ellipsis property that does exactly what I want, but I need this to be cross-browser. This property seems to be (somewhat?) standard but isn't supported by Firefox. I've found various workarounds based on overflow: hidden, but they either don't display an ellipsis (I want the user to know the content was truncated), or display it all the time (even if the content wasn't truncated). Does anyone have a good way of fitting dynamic text in a fixed layout, or is server-side truncation by logical width as good as I'm going to get for now?

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  • Porting WebGL game to iPhone's native OpenGL?

    - by ArtPulse
    We are developing a web game that uses WebGL for the two biggest parts of it. Working with HTML / CSS was too slow and too limited, so it's off the table. Thing is, iOS does not support WebGL publicly just yet, only on iAd. It is my guess Apple will eventually support it once the security issues they and Microsoft claim it has are fixed, and looks stable enough. Problem is, if Apple does not do this by the release of the next mayor iOS version, then we will have in our hands a mobile WebGL game that does not run. 6 months of development and testing to waste. So, questions: If that was the case, how viable (regarding amount of time) is it porting the WebGL part of the game to native iPhone OpenGL? I'm afraid that porting will take longer than the development of the game itself. I saw posts on Stack Overflow (like this) that suggested, on Android, adding the OpenGL interface manually to a WebKit element. It'd be slower than native. But either way... Is this something that could be accepted in the AppStore? Apple is very restrictive with these kind of stuff... Thank you all for your time!

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