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  • Android lifecycle: Fill in data in activity in onStart() or onResume()?

    - by pjv
    Should you get data via a cursor and fill in the data on the screen, such as setting the window title, in onStart() or onResume()? onStart() would seem the logical place because after onStart() the Activity can already be displayed, albeit in the background. Notably I was having a problem with a managed dialog that made me rethink this. If the user rotates the screen while the dialog is still open, onCreateDialog() and onPrepareDialog() are called between onStart() and onResume(). If the dialog needs to be based on the data you need to have the data before onResume(). If I'm correct about onStart() then why does the Notepad example give a bad example by doing it in onResume()? See http://developer.android.com/resources/samples/NotePad/src/com/example/android/notepad/NoteEditor.html NoteEditor.java line 176 (title = mCursor.getString...). Also, what if my Activity launches another Actvity/Dialog that changes the data my cursor is tracking. Even in the simplest case, does that mean that I have to manually update my previous screen (a listener for a dialog in the main activity), or alternatively that I have to register a ContentObserver, since I'm no longer updating the data in onResume() (though I could update it twice of course)? I know it's a basic question but the dialog only recently, to my surprise, made me realize this.

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  • how can i make sure to get the server response correctly when i invoke the server with QNetworkReque

    - by noname
    I wrote the server site call in Qt, but i haven't get the server response for every server invoking. I have to use the server reply to continue the program flow. The request is correctly reached to server and server do reply.The server is also on my machine. Here is the code how i make the server site call; QNetworkAccessManager nam1 = new QNetworkAccessManager(this); qnetmg=nam1; QObject::connect(nam1, SIGNAL(finished(QNetworkReply*)),this,SLOT(finishedGettingMarker(QNetworkReply*))); QString strurl="http://localhost:8080/ServerWeb"; QUrl url(strurl); QNetworkRequest preq(url); QNetworkReply* reply = nam1->get(preq); qreply=reply; Inside finisedGettingMarker slot, i have already eliminate for QNetworkReply-error case and i used one global variable for QNetworkAccessManager;"qnetmg" and one global variable for QNetworkReply;"qreply". And also i make qnetmg.disconnect(this,0); and qreply.abort(); inside that slot method. But the problem is i haven't got the response for every server invoking time. If anyone who know the way to solve it , please reply me. This situation happened only in Opera. Thanks in advance.

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  • j_security_check to SSO in different module under Oracle App Server?

    - by thebearinboulder
    I have an existing j2ee application running on Oracle App Server. It is targeted towards paying customers so the content is secured and a SSO module properly intercepts all requests for secured content. Now the company is adding a unbranded public-facing module with a number of unsecured pages. At one point the user is expected to register for a free account and log in to proceed further. Think doctors adding a public-facing site with information for potential patients, or lawyers adding a public-facing site with information for potential clients. There's some information on the session and the usual approach would be to authenticate the user, persist the session information using the now-known user id, invalidate the existing session (to prevent certain types of attacks), the reload the session information before returning to the user. I can't just persist it under the session id since that's about to change. The glitch is that the existing application already has an SSO module and I get a 404 error every time I try to direct to j_security_check. I've tried that, /sso/j_security_check, even http://localhost/sso/j_security_check, all without success. I noticed that an earlier question said that tomcat requires access to a secured page before j_security_check is even visible. I don't know if that's the case with Oracle AS. Ideas? Or is the best approach to continue arguing that we have a different user base so it would be better to handle authentication in our own module anyway?

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  • Detecting scroll in Jquery Mobile

    - by noway
    I can't detect whether the page is scrolled or not with jquery mobile. Scrolltop always return 0 in any case. <script> var interval = setInterval(function() { alert($("#articlecontent").scrollTop()); //alert($(window).scrollTop()); //alert($("#maindiv").scrollTop()); } }, 3000); </script> <div data-role="page" id="maindiv"> <div class="ui-bar ui-bar-b"> </div> <div id='articlecontent' data-role="content" data-iscroll> sldfjlkjsl lksjd kls df hjks djkh sdjfkh sjkf jksd jkhsdf jkhsd hjwiuhhfg skd jkshd fkj fkjsg kjhsdkjf sldfjlkjsl lksjd kls df hjks djkh sdjfkh sjkf jksd jkhsdf jkhsd hjwiuhhfg skd jkshd fkj fkjsg kjhsdkjf sldfjlkjsl lksjd kls df hjks djkh sdjfkh sjkf jksd jkhsdf jkhsd hjwiuhhfg skd jkshd fkj fkjsg kjhsdkjf </div> <div data-role="footer" data-id="foo1"> </div> </div>

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  • Need help getting parent reference to child view controller

    - by Andy
    I've got the following code in one of my view controllers: - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { switch (indexPath.section) { case 0: // "days" section tapped { DayPicker *dayPicker = [[DayPicker alloc] initWithStyle:UITableViewStylePlain]; dayPicker.rowLabel = self.activeDaysLabel; dayPicker.selectedDays = self.newRule.activeDays; [self.navigationController pushViewController:dayPicker animated:YES]; [dayPicker release]; break; ... Then, in the DayPicker controller, I do some stuff to the dayPicker.rowLabel property. Now, when the dayPicker is dismissed, I want the value in dayPicker.rowLabel to be used as the cell.textLabel.text property in the cell that called the controller in the first place (i.e., the cell label becomes the option that was selected within the DayPicker controller). I thought that by using the assignment operator to set dayPicker.rowLabel = self.activeDaysLabel, the two pointed to the same object in memory, and that upon dismissing the DayPicker, my first view controller, which uses self.activeDaysLabel as the cell.textLabel.text property for the cell in question, would automagically pick up the new value of the object. But no such luck. Have I missed something basic here, or am I going about this the wrong way? I originally passed a reference to the calling view controller to the child view controller, but several here told me that was likely to cause problems, being a circular reference. That setup worked, though; now I'm not sure how to accomplish the same thing "the right way." As usual, thanks in advance for your help.

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  • How can i test my TSQL syntax?

    - by acidzombie24
    Quick question: How do i get some kind of database to use to test my sql syntax and create basic data. I have Sqlite Code which i'll soon put on a server. I have sql server 2008 installed with visual studio 2010. I tried connecting to the database and had no luck. I also tried using a .mdf file instead thinking its a file and i wont have connectivity issues. Wrong, i still couldnt connect and i used this site to help me (i'm aware its 2005) In that case i used var conn = new SqlConnection(@"Server=.\SQLExpress;AttachDbFilename=C:\dev\src\test\SQL_DB_VS_Test\test.mdf;Database=dbo;Trusted_Connection=Yes;"); exception Unable to open the physical file "C:\dev\src\test\SQL_DB_VS_Test\test.mdf". Operating system error 5: "5(Access is denied.)". Cannot attach the file 'C:\dev\src\test\SQL_DB_VS_Test\test.mdf' as database 'dbo'. with trusted = no i get Login failed for user ''. (What user am i suppose to set...). I created the .mdf with visual studio somehow.

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  • Retrieving friend's likes from the Facebook Graph API

    - by Joe Frank
    Howdy- I have been tooling around with the Facebook Graph API and successfully retrieved back a list of my likes, and a list of my friends (once I authenticated using OAuth). But what I really want to achieve is pulling back my friend's likes. When I try and do that, obviously using the same URL that I use to pull back my own likes but subbing the friend's user id for "me", I don't get anything back, unless they have installed the app as well. Then I get them no problem. To be clear, I can only see the likes of friends who have installed my application. So clearly I am running into a security/rights issue of some sort. I could see where this would be the case; you simply aren't allowed to see your friend's likes unless they have installed the same app. Fair enough, but then how is blekko.com doing it? I even tried using FQL without much luck. I suspect I am missing something totally obvious. Anyone had any luck with this? Maybe with the Javascript API or one of the other access methods? Thanks in advance for any guidance.

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  • OCR combined with font recognition?

    - by Adam
    I have a bold idea where a user could take an image like the following and in a few seconds of processing, be able to edit a document which looks roughly the same. The software would use WhatTheFont (or something similar) to recognize the fonts used, and OCR and other software to handle the font size, color, line-spacing, and of course the text content itself. In the case of the example image, there would be three separate "textboxes" produced, each starting at the upper left corner of the text, and extending as far to the bottom right as it could before running into another text box. So the user would then see something like this: (The rectangles are just used to show the boundaries of each textbox.) From here, the user would be able to edit the text in each of these boxes to create a new document. Of course there are tons of obvious uses for such an application, especially on a mobile phone with a built in camera. So my questions are the following: I doubt the answer is yes, but does anything do this already? If I'm going to try to build this, what should I write it in? Can I use Python? What would be the best OCR libraries to start with? Is there a service other than WhatTheFont for font recognition that has better API support? Anybody want to help me build it? :) etc. etc. Update: One thing I wanted to mention (but forgot) is I would also like the background to be preserved. In other words, if the example above had an image behind the text, I'd like the document to use that image with text removed. I know this complicates things a lot because that would require some image editing techniques too (something akin to Photoshop CS5' "content-aware fill"). But if we can solve diminished reality on iPhones, I think we can figure this out!

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  • What is the worst gotcha in WPF?

    - by David
    Hi, I've started to make myself a list of "WPF gotchas": things that bug me and that I had to write down to remember because I fall for them every time.... Now, I'm pretty sure you all stumbled upon similar situations at one point, and I would like you to share your experience on the subject: What is the gotcha that gets you all the time? the one you find the most annoying? (I have a few issues that seem to be without explanation, maybe your submissions will explain them) Here are a few of my "personnal" gotchas (randomly presented): For a MouseEvent to be fired even when the click is on the "transparent" background of a control (e.g. a label) and not just on the content (the Text in this case), the control's Background has to be set to "Brushes.Transparent" and not just "null" (default value for a label) A WPF DataGridCell's DataContext is the RowView to whom the cell belong, not the CellView When inside a ScrollViewer, a Scrollbar is managed by the scrollviewer itself (i.e. setting properties such as ScrollBar.Value is without effect) Key.F10 is not fired when you press "F10", instead you get Key.System and you have to go look for e.SystemKey to get the Key.F10 ... and now you're on.

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  • Consecutive absences in MySQL

    - by pepersview
    Hi, I have 2 tables in my db: students and absences. In students: id_student, s_name; and in absences: id_student, date, day(the day of the week as number-it's not so important); I would like to get the students that were absent for more than 2 days consecutive and the dates. At the moment I have the next query: /*To control when the days are in the same week*/ SELECT id_student, date, dayname(date),date_add(date, INTERVAL 1 DAY) AS a, dayname(date_add(date, INTERVAL 1 DAY)) AS an, date_add(date, INTERVAL 2 DAY) AS b, dayname(date_add(date, INTERVAL 2 DAY)) AS bn FROM absences AS a WHERE id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date, INTERVAL 1 DAY) ) AND id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date,INTERVAL 2 DAY) ) UNION /*To control when the days jump to the next week*/ SELECT id_student, date, dayname(date),date_add(date, INTERVAL 3 DAY) AS a, dayname(date_add(date, INTERVAL 3 DAY)) AS an, date_add(date, INTERVAL 4 DAY) AS b, dayname(date_add(date, INTERVAL 4 DAY)) AS bn FROM absences AS a WHERE id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date, INTERVAL 3 DAY) ) AND id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date,INTERVAL 4 DAY) ) /* To avoid the case (Monday-Thursday-Friday) to be consider as consecutive days*/ AND WEEKDAY(date) !=0 Thanks

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  • What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

    - by dcuccia
    I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

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  • Building a J2EE dev/test setup on a single PC

    - by John
    It's been a while since I did Java work, and even then I was never responsible for starting a large project from the very start... there were test/staging/production systems already running, etc, etc. Now I am looking to start a J2EE project from scratch on my trusty workstation, which has never been used for Java development and runs Windows 7 64bit. First of all, I'll be getting Eclipse. As far as writing the code goes I'm pretty happy. And running it through Eclipse is OK, but what I'd really want is to have a VM running MySQL and TomCat on which I can properly deploy my project and run/debug it 'remotely' from my dev PC. And I guess this should be done using Ant instead of letting Eclipse build the WAR for me, so that I don't end up with a dependence on Eclipse. I'm certain Eclipse can do this, so you hit a button and it runs Ant scripts, deploys and debugs for instance, but very hazy on it. Are there any good guides on this? I don't want to be taught Java, or even Ant, but rather the 'glue' parts like getting my test VM up and running under Windows, getting a build/test/deploy/run pipeline running through Eclipse, etc. One point, I only plan to use Windows... hosting a Windows VM on my Windwos desktop. And while I can use command-line tools like ant/svn, I'm much more a GUI person who loves IDE integration... I'd rather this didn't end up an argument about Linux or Vi, etc! I am looking for free, but am a MAPS subscriber, and run Win7 Ultimate in case that makes a difference as far as free VM solutions.

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  • Search and remove an element in mulit-dimentional array in php depending on a criteria

    - by Nadeem
    I've a simple question about multi-dim array, I want to remove any redundent element let's say in my case, [serviceMethod] => PL is coming 2 times, I want to search 'PL' with respect of [APIPriceTax] if an element has a lower price I want to keep it and remove the other one in array Array ( [0] => Array ( [carrierIDs] => 150 [serviceMethod] => CP [APIPriceTax] => 30.63 [APIPriceWithOutTax] 28.32 [APIServiceName] => Xpresspost USA [APIExpectedTransitDay] => 2 ) [1] => Array ( [carrierIDs] => 155 [serviceMethod] => PL [APIPriceTax] => 84.13 [APIPriceWithOutTax] => 73.8 [APIServiceName] => PurolatorExpressU.S. [APIExpectedTransitDay] => 1 ) [2] => Array ( [carrierIDs] => 164 [serviceMethod] => PL [APIPriceTax] => 25.48 [APIPriceWithOutTax] => 22.35 [APIServiceName] => PurolatorGroundU.S. [APIExpectedTransitDay] => 3 ) ) This is my pseudo code: Where $carrierAddedToList is the actual array $newCarrierAry = function($carrierAddedToList) { $newArray = array(); foreach($carrierAddedToList as $cV => $cK) { if( !in_array($cK['serviceMethod'],$newArray) ) { array_push($newArray, $cK['serviceMethod']); } } return $newArray; } ; print_r($newCarrierAry($carrierAddedToList));

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  • MySQL Query - WHERE and IF?

    - by Prash
    I'm not quite sure how to right this query. Basically, I'm going to have a table with two columns (OS and country_code) - more columns too, but those are the conditional ones. These will be either set to 0 for all, or specific ones, separated by commas. Now, what I'm trying achieve is pull data from the table if the OS and country_code = 0, or if they contain matching data (separated by commas). Then, I have a column for time. I want to select rows where the time is GREATER than the time column, unless the column time_t is set to false, in which case this shouldn't matter. I hope I explained it right? This is what I kind of have so far: $get = $db->prepare("SELECT * FROM commands WHERE country_code = 0 OR country_code LIKE :country_code AND OS = 0 OR OS LIKE :OS AND IF (time_t = 1, expiry > NOW()) "); $get->execute(array( ':country_code' => "%{$data['country_code']}%", ':OS' => "%{$data['OS']}%" ));

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  • PHP: Check if 0?

    - by tarnfeld
    Hi, I am using a class which returns me the value of a particular row and cell of an excel spreadsheet. To build up an array of one column I am counting the rows and then looping through that number with a for() loop and then using the $array[] = $value to set the incrementing array object's value. This works great if none of the values in a cell are 0. The class returns me a number 0 so it's nothing to do with the class, I think it's the way I am looping through the rows and then assigning them to the array... I want to carry through the 0 value because I am creating graphs with the data afterwards, here is the code I have. // Get Rainfall $rainfall = array(); for($i=1;$i<=$count;$i++) { if($data->val($i,2) != 'Rainfall') // Check if not the column title { $rainfall[] = $data->val($i,2); } } For your info $data is the excel spreadsheet object and the method $data->val(row,col) is what returns me the value. In this case I am getting data from column 2. Screenshot of spreadsheet http://cl.ly/1Dmy Thanks! All help is very much appreciated!

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  • C++, inject additional data in a method

    - by justik
    I am adding the new modul in some large library. All methods here are implemented as static. Let mi briefly describe the simplified model: typedef std::vector<double> TData; double test ( const TData &arg ) { return arg ( 0 ) * sin ( arg ( 1 ) + ...;} double ( * p_test ) ( const TData> &arg) = &test; class A { public: static T f1 (TData &input) { .... //some computations B::f2 (p_test); } }; Inside f1() some computations are perfomed and a static method B::f2 is called. The f2 method is implemented by another author and represents some simulation algorithm (example here is siplified). class B { public: static double f2 (double ( * p_test ) ( const TData &arg ) ) { //difficult algorithm working p_test many times double res = p_test(arg); } }; The f2 method has a pointer to some weight function (here p_test). But in my case some additional parameters computed in f1 for test() methods are required double test ( const TData &arg, const TData &arg2, char *arg3.... ) { } How to inject these parameters into test() (and so to f2) to avoid changing the source code of the f2 methods (that is not trivial), redesign of the library and without dirty hacks :-) ? The most simple step is to override f2 static double f2 (double ( * p_test ) ( const TData &arg ), const TData &arg2, char *arg3.... ) But what to do later? Consider, that methods are static, so there will be problems with objects. Thanks for your help.

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  • Many tables for many users?

    - by Seagull
    I am new to web programming, so excuse the ignorance... ;-) I have a web application that in many ways can be considered to be a multi-tenant environment. By this I mean that each user of the application gets their own 'custom' environment, with absolutely no interaction between those users. So far I have built the web application as a 'single user' environment. In other words, I haven't actually done anything to support multi-users, but only worked on the functionality I want from the app. Here is my problem... What's the best way to build a multi-user environment: All users point to the same 'core' backend. In other words, I build the logic to separate users via appropriate SQL queries (eg. select * from table where user='123' and attribute='456'). Each user points to a unique tablespace, which is built separately as they join the system. In this case I would simply generate ALL the relevant SQL tables per user, with some sort of suffix for the user. (eg. now a query would look like 'select * from table_ where attribute ='456'). In short, it's a difference between "select * from table where USER=" and "select * from table_USER".

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  • Starting a process synchronously, and "streaming" the output

    - by Benjol
    I'm looking at trying to start a process from F#, wait till it's finished, but also read it's output progressively. Is this the right/best way to do it? (In my case I'm trying to execute git commands, but that is tangential to the question) let gitexecute (logger:string->unit) cmd = let procStartInfo = new ProcessStartInfo(@"C:\Program Files\Git\bin\git.exe", cmd) // Redirect to the Process.StandardOutput StreamReader. procStartInfo.RedirectStandardOutput <- true procStartInfo.UseShellExecute <- false; // Do not create the black window. procStartInfo.CreateNoWindow <- true; // Create a process, assign its ProcessStartInfo and start it let proc = new Process(); proc.StartInfo <- procStartInfo; proc.Start() |> ignore // Get the output into a string while not proc.StandardOutput.EndOfStream do proc.StandardOutput.ReadLine() |> logger What I don't understand is how the proc.Start() can return a boolean and also be asynchronous enough for me to get the output out of the while progressively. Unfortunately, I don't currently have a large enough repository - or slow enough machine, to be able to tell what order things are happening in...

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  • C#: Thread.CurrentThread.CurrentUICulture not working consistently

    - by xTRUMANx
    I've been working on a pet project on the weekends to learn more about C# and have encountered an odd problem when working with localization. To be more specific, the problem I have is with System.Threading.Thread.CurrentThread.CurrentUICulture. I've set up my app so that the user can quickly change the language of the app by clicking a menu item. The menu item in turn, saves the two-letter code for the language (e.g. "en", "fr", etc.) in a user setting called 'Language' and then restarts the application. Properties.Settings.Default.Language = "en"; Properties.Settings.Default.Save(); Application.Restart(); When the application is started up, the first line of code in the Form's constructor (even before InitializeComponent()) fetches the Language string from the settings and sets the CurrentUICulture like so: public Form1() { Thread.CurrentThread.CurrentUICulture = new CultureInfo(Properties.Settings.Default.Language); InitializeComponent(); } The thing is, this doesn't work consistently. Sometimes, all works well and the application loads the correct language based on the string saved in the settings file. Other times, it doesn't, and the language remains the same after the application is restarted. At first I thought that I didn't save the language before restarting the application but that is definitely not the case. When the correct language fails to load, if I were to close the application and run it again, the correct language would come up correctly. So this implies that the Language string has been saved but the CurrentUICulture assignment in my form constructor is having no effect sometimes. Any help? Is there something I'm missing of how threading works in C#? This could be machine-specific, so if it makes any difference I'm using Pentium Dual-Core CPU.

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  • Making IE "forget" information entered in form when using back button.

    - by typoknig
    I have a page with a form where many of the fields are populated from variables passed in the URL. Those fields are disabled (NON-EDITABLE) and are only there for the user to view. The remaining fields require user input and are NOT disabled (EDITABLE). When the form is submitted a confirmation page comes up. It may be the case that the user needs to submit several of these forms where the NON-EDITABLE information is identical from form to form, so being able to go back to the form page from the confirmation page would save a lot of time. The way I want this to work is when a user presses the back button all the NON-EDITABLE fields are populated, but the EDITABLE fields are blank. This is what Firefox is doing, but IE8 is does not "forget" what has been entered in the EDITABLE fields. To disable the cache the following appears at the beginning of my page AND at the end of my page. <head> <meta http-equiv="Pragma" content="no-cache"/> <meta http-equiv="Cache-Control" content="no-store"/> <head/> What more must I do to make IE forget what was entered in the EDITABLE fields when the back button is pressed? All of my pages are generated with PHP if that matters. EDIT: It appears to me that this is a problem of IE caching my page even though I have told it not to. Are my meta tags correct? Do I need to do something else to prevent IE from caching my page?

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  • Prevent Activity from saving state when user selects back button

    - by martinjd
    I have an Activity with a list that is bound to a ListAdapter reading data into a ArrayList from a database. All is well when the data is first loaded. While the Activity is open and the list is being displayed it is possible and likely that the data in the database will be updated by a service but the list does not reflect the changes because the ArrayList does not know about the changes. If the Activity is no longer in the foreground as would be the case if the user goes to the home screen and then is brought back to the foreground I would like for the Activity to not display what it did prior but rather reload the data using the ListAdapter the view is bound to. I think something needs to call finish() but I am not sure what. This is what I have in the Activity. @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); setUpViews(); app = (MyApplication) getApplication(); adapter = new MyListAdapter(this, app.getMyEvents()); setListAdapter(adapter); } @Override protected void onResume() { super.onResume(); adapter.forceReload(); }

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  • SYN receives RST,ACK very frequently

    - by user1289508
    Hi Socket Programming experts, I am writing a proxy server on Linux for SQL Database server running on Windows. The proxy is coded using bsd sockets and in C, and it is working just fine. When I use a database client (written in JAVA, and running on a Linux box) to fire queries (with a concurrency of 100 or more) directly to the Database server, not experiencing connection resets. But through my proxy I am experiencing many connection resets. Digging deeper I came to know that connection from 'DB client' to 'Proxy' always succeeds but when the 'Proxy' tries to connect to the DB server the connection fails, due to the SYN packet getting RST,ACK. That was to give some background. The question is : Why does sometimes SYN receives RST,ACK? 'DB client(linux)' to 'Server(windows)' ---- Works fine 'DB client(linux) to 'Proxy(Linux)' to 'Server(windows)' ----- problematic I am aware that this can happen in "connection refused" case but this definitely is not that one. SYN flooding might be another scenario, but that does not explain fine behavior while firing to Server directly. I am suspecting some socket option setting may be required, that the client does before connecting and my proxy does not. Please put some light on this. Any help (links or pointers) is most appreciated. Additional info: Wrote a C client that does concurrent connections, which takes concurrency as an argument. Here are my observations: - At 5000 concurrency and above, some connects failed with 'connection refused'. - Below 2000, it works fine. But the actual problem is observed even at a concurrency of 100 or more. Note: The problem is time dependent sometimes it never comes at all and sometimes it is very frequent and DB client (directly to server) works fine at all times .

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  • Aliasing `T*` with `char*` is allowed. Is it also allowed the other way around?

    - by StackedCrooked
    Note: This question has been renamed and reduced to make it more focused and readable. Most of the comments refer to the old text. According to the standard objects of different type may not share the same memory location. So this would not be legal: int i = 0; short * s = reinterpret_cast<short*>(&i); // BAD! The standard however allows an exception to this rule: any object may be accessed through a pointer to char or unsigned char: int i = 0; char * c = reinterpret_cast<char*>(&i); // OK However, it is not clear to me if this is also allowed the other way around. For example: char * c = read_socket(...); unsigned * u = reinterpret_cast<unsigned*>(c); // huh? Summary of the answers The answer is NO for two reasons: You an only access an existing object as char*. There is no object in my sample code, only a byte buffer. The pointer address may not have the right alignment for the target object. In that case dereferencing it would result in undefined behavior. On the Intel and AMD platforms it will result performance overhead. On ARM it will trigger a CPU trap and your program will be terminated! This is a simplified explanation. For more detailed information see answers by @Luc Danton, @Cheers and hth. - Alf and @David Rodríguez.

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  • How to enforce that HTTP client uses conditional requests for updates?

    - by Day
    In a (proper RMM level 3) RESTful HTTP API, I want to enforce the fact that clients should make conditional requests when updating resources, in order to avoid the lost update problem. What would be an appropriate response to return to clients that incorrectly attempt unconditional PUT requests? I note that the (abandoned?) mod_atom returns a 405 Method Not Allowed with an Allow header set to GET, HEAD (view source) when an unconditional update is attempted. This seems slightly misleading - to me this implies that PUT is never a valid method to attempt on the resource. Perhaps the response just needs to have an entity body explaining that If-Match or If-Unmodified-Since must be used to make the PUT request conditional in which case it would be allowed? Or perhaps a 400 Bad Request with a suitable explanation in the entity body would be a better solution? But again, this doesn't feel quite right because it's using a 400 response for a violation of application specific semantics when RFC 2616 says (my emphasis): The request could not be understood by the server due to malformed syntax. But than again, I think that using 400 Bad Request for application specific semantics is becoming a widely accepted pragmatic solution (citation needed!), and I'm just being overly pedantic.

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  • The HTTP verb POST used to access path '[my path]' is not allowed.

    - by Jed
    I am receiving an error that states: "The HTTP verb POST used to access path '[my path]' is not allowed.". The error is being caused by the fact that I am implementing an HTML form element that uses the POST method and does not explicitly define an .aspx page in its ACTION parameter. For example: <form action="" method="post"> <input type="submit" /> </form> The HTML above is on a file at "/foo/default.aspx". Now, if the user points the URL to the root directory "foo" without specifying the aspx file (i.e. "http://localhost/foo") and then submits the form, the error "The HTTP verb POST used to access path '/foo' is not allowed." will be thrown. However, if the user goes to "http://localhost/foo/default.aspx" and then submits the form, all goes well (even if the ACTION parameter is left empty). Note: If I explicitly add the name of the .aspx (default.aspx) page to the ACTION parameter, no errors are thrown. So the example below works fine regardless if the user defines the name of the file in the URL or not. <form action="default.aspx" method="post"> <input type="submit" /> </form> I was curious as to why the error was being thrown, so I read a Microsoft KB that states This problem occurs because a client makes an HTTP request by sending the POST method to a static HTML page. Static HTML pages do not support the POST method. I suppose the core of the explanation makes sense, however in my case, my form is not being sent to a static html page - it's being sent to the same page that the html form lives on (default.aspx)... this is implicit to an ACTION param that is left empty. Is it possible to configure IIS (or otherwise) that will allow us to do form POSTing and keep the ACTION param empty?

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