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• Dealing with missing messages in JavaScript when using BOSH

  - by JamieD

  We recently went into private beta on our flagship product and had a small launch event. Unfortunately the venue had a terrible wireless connection and packets were being dropped left right and centre causing havoc with out system, basically it wasn't able to work at all! Luckily we were able to switch to a different network and rescue the demo. This highlighted something that I knew was already an issue but hadn't appreciated quite how much of an issue it could be. Our system relies heavily on BOSH and has a rather large JavaScript code base which now works rather well under good network conditions. However we need to make it work well under bad network conditions as well. Due to the way that XMPP works, a fire and forget system, it's not easy to tell if a message you sent, or were supposed to receive, was actually sent or received. For instance, we have an offer system, one user will send an offer to another over BOSH. When this message is received by the server a message is published to the offering users offers_sent PEP node and a similar message to the receiving users offers_received PEP node. While the sending user is able to tell if their offer was send (relatively) easily, if the notification to the receiving user is never received that user will never know it missed a message. A little about out JavaScript setup, it has 4 main layers: StropheJS An MVC framework for dealing with low level tasks and to build on top of An application layer which contains the app logic routes, controllers models etc. as well as a browser cache of the model data A UI layer that receives events and publishes events to and from the application layer One way to solve the missing messages issue would be to periodically check the PEP nodes for new data that the browser doesn't know about. If a new message was discovered the browsers cache would be invalidated and all new data would be requested from the server. I'm not sure this is the best way to go and it also doesn't cover all situations. We certainly don't want to get into the situation where we are sending messages to confirm the previous message was received at it's destination as this would double the network traffic. With the number of real time websites growing daily this is an issue that must have been encountered by other developers, it would be interesting to see how it's been solved by others. As far as I can see there are two situations in which messages go missing: On poor connections messages are not sent or received due to the packets being dropped Involving navigating between pages, a message is received by the browser but is not fully processed and stored in the local cache before the page is unloaded. Or a message is added to the send queue but never sent before the page is unloaded I suspect the hardest issue to solve will be number 2. Any thoughts on the subject would be much appreciated.

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• server|configuration problem, a php script just die with no error log & no reason

  - by Roberto

  Hi (first of all, thanks for your attention & sorry for my bad english hahaha also this is not a programming error, or thats what I think, I think this is an error in some configuration of the server or something else but I dont know what) I have a php script (is running like a process of linux, its not running on the web browser) that send SMS via SMPP on the port 2055 (using sockets in php) & then inserts like 10,000 rows into a dababase on MySQL, the script gets the data from a XML file; firts it was running in a shared server (Hostgator is our hosting provider) & at the begining it worked fine, with no trouble, but 5 months later an error appear, the process just die with no reason, the script only sent & inserted 700 rows in the table of the database & the process didnt show any warning or error, nothing appears in the error logs, & I didnt make any change in the script Hostgator never helped us hahaha so we decided to move the script from the shared server to a dedicated server; I thought it was a memory problem or something like that, but when we move the script to the dedicated server the problem just get worse, the script die when has just sent & inserted 40 to 50 rows to the database the information about this error: the shared server is on Red Hat 4.1.2-46 & the dedicated server is on CentOS 5.4 I have commented the line that sends the SMS, & the problem remains in the shared server, at the begining the script was fine, but then the script started to die when has just inserted 700 aprox. in the database, & now the script is dying when has inserted 2500 rows, its better but we didnt change anything in the dedicated server, the script dies when has just inserted like 40 row in the table the script, before it dies, change to a zombie process & we dont know why the usage of memory appears to be 0.3%, and of the cpu appears to be 0.7% to 1% I have changed the max memory limit of php to 128Mb, and even to -1 (so php wont have any limit) but the problem remains we have the limit of 50 connections of mysql at the same time, so I think this is not the problem Im using mysqli to connect from php to mysql Hostgator report that they haven't made any change or update in the servers what could be the problem?? what should I do??? what should I search??? is something in the logic Im missing?? what steps do I have to follow when managing & searching problems of process on Linux??? thank you very much, I think this is not a programming problem, but you have more experience than me, you can tell me thanks!!! bye!!! :)

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• Best Practices / Patterns for Enterprise Protection/Remediation of SSNs (Social Security Numbers)

  - by Erik Neu

  I am interested in hearing about enterprise solutions for SSN handling. (I looked pretty hard for any pre-existing post on SO, including reviewing the terriffic SO automated "Related Questions" list, and did not find anything, so hopefully this is not a repeat.) First, I think it is important to enumerate the reasons systems/databases use SSNs: (note—these are reasons for de facto current state—I understand that many of them are not good reasons) Required for Interaction with External Entities. This is the most valid case—where external entities your system interfaces with require an SSN. This would typically be government, tax and financial. SSN is used to ensure system-wide uniqueness. SSN has become the default foreign key used internally within the enterprise, to perform cross-system joins. SSN is used for user authentication (e.g., log-on) The enterprise solution that seems optimum to me is to create a single SSN repository that is accessed by all applications needing to look up SSN info. This repository substitutes a globally unique, random 9-digit number (ASN) for the true SSN. I see many benefits to this approach. First of all, it is obviously highly backwards-compatible—all your systems "just" have to go through a major, synchronized, one-time data-cleansing exercise, where they replace the real SSN with the alternate ASN. Also, it is centralized, so it minimizes the scope for inspection and compliance. (Obviously, as a negative, it also creates a single point of failure.) This approach would solve issues 2 and 3, without ever requiring lookups to get the real SSN. For issue #1, authorized systems could provide an ASN, and be returned the real SSN. This would of course be done over secure connections, and the requesting systems would never persist the full SSN. Also, if the requesting system only needs the last 4 digits of the SSN, then that is all that would ever be passed. Issue #4 could be handled the same way as issue #1, though obviously the best thing would be to move away from having users supply an SSN for log-on. There are a couple of papers on this: UC Berkely: http://bit.ly/bdZPjQ Oracle Vault: bit.ly/cikbi1

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• Dependency Injection and Unit of Work pattern

  - by sunwukung

  I have a dilemma. I've used DI (read: factory) to provide core components for a homebrew ORM. The container provides database connections, DAO's,Mappers and their resultant Domain Objects on request. Here's a basic outline of the Mappers and Domain Object classes class Mapper{ public function __constructor($DAO){ $this->DAO = $DAO; } public function load($id){ if(isset(Monitor::members[$id]){ return Monitor::members[$id]; $values = $this->DAO->selectStmt($id); //field mapping process omitted for brevity $Object = new Object($values); return $Object; } } class User(){ public function setName($string){ $this->name = $string; //mark modified by means fair or foul } } The ORM also contains a class (Monitor) based on the Unit of Work pattern i.e. class Monitor(){ private static array modified; private static array dirty; public function markClean($class); public function markModified($class); } The ORM class itself simply co-ordinates resources extracted from the DI container. So, to instantiate a new User object: $Container = new DI_Container; $ORM = new ORM($Container); $User = $ORM->load('user',1); //at this point the container instantiates a mapper class //and passes a database connection to it via the constructor //the mapper then takes the second argument and loads the user with that id $User->setName('Rumpelstiltskin');//at this point, User must mark itself as "modified" My question is this. At the point when a user sets values on a Domain Object class, I need to mark the class as "dirty" in the Monitor class. I have one of three options as I can see it 1: Pass an instance of the Monitor class to the Domain Object. I noticed this gets marked as recursive in FirePHP - i.e. $this-Monitor-markModified($this) 2: Instantiate the Monitor directly in the Domain Object - does this break DI? 3: Make the Monitor methods static, and call them from inside the Domain Object - this breaks DI too doesn't it? What would be your recommended course of action (other than use an existing ORM, I'm doing this for fun...)

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• Twisted: why is it that passing a deferred callback to a deferred thread makes the thread blocking a

  - by surtyaarthoughts

  I unsuccessfully tried using txredis (the non blocking twisted api for redis) for a persisting message queue I'm trying to set up with a scrapy project I am working on. I found that although the client was not blocking, it became much slower than it could have been because what should have been one event in the reactor loop was split up into thousands of steps. So instead, I tried making use of redis-py (the regular blocking twisted api) and wrapping the call in a deferred thread. It works great, however I want to perform an inner deferred when I make a call to redis as I would like to set up connection pooling in attempts to speed things up further. Below is my interpretation of some sample code taken from the twisted docs for a deferred thread to illustrate my use case: #!/usr/bin/env python from twisted.internet import reactor,threads from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(): print 'doing lookup... this may take a while' time.sleep(10) return 'results from redis' def result(res): print res def main(): lc = LoopingCall(main_loop) lc.start(2) d = threads.deferToThread(aBlockingRedisCall) d.addCallback(result) reactor.run() if __name__=='__main__': main() And here is my alteration for connection pooling that makes the code in the deferred thread blocking : #!/usr/bin/env python from twisted.internet import reactor,defer from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(x): if x<5: #all connections are busy, try later print '%s is less than 5, get a redis client later' % x x+=1 d = defer.Deferred() d.addCallback(aBlockingRedisCall) reactor.callLater(1.0,d.callback,x) return d else: print 'got a redis client; doing lookup.. this may take a while' time.sleep(10) # this is now blocking.. any ideas? d = defer.Deferred() d.addCallback(gotFinalResult) d.callback(x) return d def gotFinalResult(x): return 'final result is %s' % x def result(res): print res def aBlockingMethod(): print 'going to sleep...' time.sleep(10) print 'woke up' def main(): lc = LoopingCall(main_loop) lc.start(2) d = defer.Deferred() d.addCallback(aBlockingRedisCall) d.addCallback(result) reactor.callInThread(d.callback, 1) reactor.run() if __name__=='__main__': main() So my question is, does anyone know why my alteration causes the deferred thread to be blocking and/or can anyone suggest a better solution?

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• Custom activity designers in Workflow Foundation 3.5: How do they work?

  - by stakx

  Intent of this post: I realise that Workflow Foundation is not extremely popular on StackOverflow and that there will probably be not many answers, or none at all. This post is intended as a resource to people trying to customise workflow activities' appearance through custom designer classes. Goals: I am attempting to create a custom designer class for Workflow activities to achieve the following: Make activities look less technical. For example, I don't necessarily want to see the internal object name as the activity's "title" -- instead, I'd like to see something more descriptive. Display the values of certain properties beneath the title text. I would like to see some properties' values directly underneath the title so that I don't need to look somewhere else (namely, at the Properties window). Provide custom drop areas and draw custom internal arrows. As an example, I would like to be able to have custom drop areas in very specific places. What I found out so far: I created a custom designer class deriving from SequentialActivityDesigner as follows: [Designer(typeof(SomeDesigner))] public partial class SomeActivity: CompositeActivity { ... } class PlainDesigner : SequentialActivityDesigner { ... } Through overriding some properties and the OnPaint method, I found out about the following correspondences between the properties and how the activity will be displayed: Figure 1. Relationship between some properties of an SequentialActivityDesigner and the displayed activity. Possible solutions for goal #1 (make activities look less technical) and goal #2 (display values of properties beneath title text): The displayed title can be changed through the Title property. If more room is required to display additional information beneath the title, the TitleHeight property can be increased (ie., override the property and make it return base.TitleHeight + n, where n is some positive integer). Override the OnPaint method and draw additional text in the area reserved through TitleHeight. Open questions: What are the connectors, connections, and connection points used for? They seem to be necessary, but for what purpose? While the drop targets can be got through the GetDropTargets method, it seems that this is not necessarily where the designer will actually place dropped activities. When an activity is dragged across a workflow, the designer displays little green plus signs where activities can be dropped; how does it figure out the locations of these plus signs? How does the designer figure out where to draw connector lines and arrows?

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• Hibernate Communications Link Failure in Hibernate Based Java Servlet application powered by MySQL

  - by Vatsala

  Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?) edit - Here are the c3p0 parameters I tried out - select 1; 2

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• A shortest path problem with superheroes and intergalactic journeys

  - by Dman

  You are a super-hero in the year 2222 and you are faced with this great challenge: starting from your home planet Ilop you must try to reach Acinhet or else your planet will be destroyed by evil green little monsters. To do this you are given a map of the universe: there are N planets and M inter-planetary connections ( bidirectional ) that bind these planets. Each connection requires a certain time and a certain amount of fuel in order for you to cover the connection from one planet to another. The total time spent going from one planet to another is obtained by multiplying the time past to cover each connection between all the planets you go through. There are some "key planets", that allow you to refuel if you arrive on those certain "key planets". A "key planet" is the planet with the property that if it disappears the road between at least two planets would be lost.(In the example posted below with the input/output files such a "key planet" is 2 because without it the road to 7 would be lost) When you start your mission you are given the possibility of choosing between K ships each with its own maximum fuel capacity. The goal is to find the SHORTEST TIME CONSUMING path but also choose the ship with the minimum fuel capacity that can cover that shortest path(this means that if more ships can cover the shortest path you choose the one with the minimum fuel capacity). Because the minimum time can be a rather large number (over long long int) you are asked to provide only the last 6 digits of the number. For a better understanding of the task, here is an example of input/output files: INPUT: mission.in 7 8 6 1 4 6 5 9 8 7 10 1 2 7 8 1 4 14 9 1 5 3 1 2 3 1 2 2 7 7 1 3 4 2 2 4 6 4 1 5 6 3 7 On the first line (in order): N M K On the second line :the number for the starting planet and the finishing planet On the third line :K numbers that represent the capacities of the ships you can choose from Then you have M lines, all of them have the same structure: Xi Yi Ti Fi-which means that there is a connection between Xi and Yi and you can cover the distance from Xi to Yi in Ti time and with a Fi fuel consumption. OUTPUT:mission.out 000014 8 1 2 3 4 On the first line:the minimum time and fuel consumption; On the second line :the path Restrictions: 2 = N = 1 000 1 = M = 30 000 1 = K = 10 000 Any suggestions or ideas of how this problem might be solved would be most welcomed.

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• Java getInputStreat SocketTimeoutException instead of NoRouteToHostException

  - by Jon

  I have an odd issue happening when trying to open multiple Input Streams (in separate threads) on Linux (RHEL). The behaviour works as expected on windows. I am kicking off 3 threads to open https connections to 3 different servers. All three are invalid IP addresses (in this test case), so I expect an NoRouteToHostException for each of them. The first two return these as expected, and quite quickly. (see stack trace below) However the third (and 4th when I tested it that way) do NOT give a no route exception. They wait for ages, and then give a SocketTimeoutException (see other stack trace below). This takes ages to come back, and does not accurately express the connection issue. The offending line of code is: reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); Has anyone seen something like this before? Are there multi-threading issues with sockets on REHL or some limit somewhere to how many can connect at once...or...something? Expected stack trace, as received for first two: java.net.NoRouteToHostException: No route to host at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:559) at sun.net.NetworkClient.doConnect(NetworkClient.java:158) at sun.net.www.http.HttpClient.openServer(HttpClient.java:394) at sun.net.www.http.HttpClient.openServer(HttpClient.java:529) at sun.net.www.protocol.https.HttpsClient.(HttpsClient.java:272) at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:329) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:172) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:916) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:158) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1177) at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:234) Unexpected stack trace, as received on 3rd: java.net.SocketTimeoutException: connect timed out at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:559) at sun.net.NetworkClient.doConnect(NetworkClient.java:158) at sun.net.www.http.HttpClient.openServer(HttpClient.java:394) at sun.net.www.http.HttpClient.openServer(HttpClient.java:529) at sun.net.www.protocol.https.HttpsClient.(HttpsClient.java:272) at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:329) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:172) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:916) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:158) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1177) at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:234)

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• Login function runs different between local and server

  - by quangnd

  Here is my check login function: protected bool checkLoginStatus(String email, String password) { bool loginStatus = false; bool status = false; try { Connector.openConn(); String str = "SELECT * FROM [User]"; SqlCommand cmd = new SqlCommand(str, Connector.conn); SqlDataAdapter da = new SqlDataAdapter(cmd); DataSet ds = new DataSet(); da.Fill(ds, "tblUser"); //check valid foreach (DataRow dr in ds.Tables[0].Rows) { if (email == dr["Email"].ToString() && password == Connector.base64Decode(dr["Password"].ToString())) { Session["login_status"] = true; Session["username"] = dr["Name"].ToString(); Session["userId"] = dr["UserId"].ToString(); status = true; break; } } } catch (Exception ex) { } finally { Connector.closeConn(); } return status; } And call it at my aspx page: String email = Login1.UserName.Trim(); String password = Login1.Password.Trim(); if (checkLoginStatus(email, password)) Response.Redirect(homeSite); else lblFailure.Text = "Invalid!"; I ran this page at localhost successful! When I published it to server, this function only can run if email and password correct! Other, error occured: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) I tried open SQL Server 2008 Configuration Manager and enable SQL Server Browser service (Logon as:NT Authority/Local Service) but it stills error. (note: here is connection string of openConn() at Localhost (run on SQLEXpress 2005) connectionString="Data Source=MYLAPTOP\SQLEXPRESS;Initial Catalog=Spider_Vcms;Integrated Security=True" /> ) At server (run on SQL Server Enterprise 2008) connectionString="Data Source=SVR;Initial Catalog=Spider_Vcms;User Id=abc;password=123456;" /> anyone have an answer for my problem :( thanks a lot!

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• HTTP caching confusion

  - by Keith

  I'm not sure whether this is a server issue, or whether I'm failing to understand how HTTP caching really works. I have an ASP MVC application running on IIS7. There's a lot of static content as part of the site including lots of CSS, Javascript and image files. For these files I want the browser to cache them for at least a day - our .css, .js, .gif and .png files rarely change. My web.config goes like this: <system.webServer> <staticContent> <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="1.00:00:00" /> </staticContent> </system.webServer> The problem I'm getting is that the browser (tested Chrome, IE8 and FX) doesn't seem to be caching the files as I'd expect. I've got the default settings (check for newer pages automatically in IE). On first visit the content downloads as expected HTTP/1.1 200 OK Cache-Control: max-age=86400 Content-Type: image/gif Last-Modified: Fri, 07 Aug 2009 09:55:15 GMT Accept-Ranges: bytes ETag: "3efeb2294517ca1:0" Server: Microsoft-IIS/7.0 X-Powered-By: ASP.NET Date: Mon, 07 Jun 2010 14:29:16 GMT Content-Length: 918 <content> I think that the Cache-Control: max-age=86400 should tell the browser not to request the page again for a day. Ok, so now the page is reloaded and the browser requests the image again. This time it gets an empty response with these headers: HTTP/1.1 304 Not Modified Cache-Control: max-age=86400 Last-Modified: Fri, 07 Aug 2009 09:55:15 GMT Accept-Ranges: bytes ETag: "3efeb2294517ca1:0" Server: Microsoft-IIS/7.0 X-Powered-By: ASP.NET Date: Mon, 07 Jun 2010 14:30:32 GMT So it looks like the browser has sent the ETag back (as a unique id for the resource), and the server's come back with a 304 Not Modified - telling the browser that it can use the previously downloaded file. It seems to me that would be correct for many caching situations, but here I don't want the extra round trip. I don't care if the image gets out of date when the file on the server changes. There are a lot of these files (even with sprite-maps and the like) and many of our clients have very slow networks. Each round trip to ping for that 304 status is taking about a 10th to a 5th of a second. Many also have IE6 which only has 2 HTTP connections at a time. The net result is that our application appears to be very slow for these clients with every page taking an extra couple of seconds to check that the static content hasn't changed. What response header am I missing that would cause the browser to aggressively cache the files? How would I set this in a .Net web.config for IIS7? Am I misunderstanding how HTTP caching works in the first place?

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• Code to show UIPickerview under clicked UITextField

  - by Chris F

  I thought I'd share a code snippet where I show a UIPickerView when you click a UITextField. The code uses a UIPickerView, but there's no reason to use a different view controller, like a UITableViewController that uses a table instead of a picker. Just create a single-view project with a nib, and add a UITextField to the view and make you connections in IB. // .h file #import @interface MyPickerViewViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource, UITextFieldDelegate> - (IBAction)dismissPickerView:(id)sender; @end // .m file #import "MyPickerViewViewController.h" @interface MyPickerViewViewController () { UIPickerView *_pv; NSArray *_array; IBOutlet __weak UITextField *_tf; BOOL _pickerViewShown; } @end @implementation MyPickerViewViewController - (void)viewDidLoad { [super viewDidLoad]; _pickerViewShown = NO; _array = [NSArray arrayWithObjects:@"One", @"Two", @"Three", @"Four", nil]; _pv = [[UIPickerView alloc] initWithFrame:CGRectZero]; _pv.showsSelectionIndicator = YES; _pv.dataSource = self; _pv.delegate = self; _tf.delegate = self; _tf.inputView = _pv; } - (IBAction)dismissPickerView:(id)sender { [_pv removeFromSuperview]; [_tf.inputView removeFromSuperview]; [_tf resignFirstResponder]; _pickerViewShown = NO; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (BOOL)textFieldShouldBeginEditing:(UITextField *)textField { if (!_pickerViewShown) { [self setRectForPickerViewRelativeToTextField:textField]; [self.view addSubview:_tf.inputView]; _pickerViewShown = YES; } else { [self dismissPickerView:self]; } return NO; } - (void)setRectForPickerViewRelativeToTextField:(UITextField*)textField { CGFloat xPos = textField.frame.origin.x; CGFloat yPos = textField.frame.origin.y; CGFloat width = textField.frame.size.width; CGFloat height = textField.frame.size.height; CGFloat pvHeight = _pv.frame.size.height; CGRect pvRect = CGRectMake(xPos, yPos+height, width, pvHeight); _pv.frame = pvRect; } - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { return [_array objectAtIndex:row]; } - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { return 1; } - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { return _array.count; } - (void) pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { _tf.text = [_array objectAtIndex:row]; [self dismissPickerView:self]; } @end

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• Memory management with Objective-C Distributed Objects: my temporary instances live forever!

  - by jkp

  I'm playing with Objective-C Distributed Objects and I'm having some problems understanding how memory management works under the system. The example given below illustrates my problem: Protocol.h #import <Foundation/Foundation.h> @protocol DOServer - (byref id)createTarget; @end Server.m #import <Foundation/Foundation.h> #import "Protocol.h" @interface DOTarget : NSObject @end @interface DOServer : NSObject < DOServer > @end @implementation DOTarget - (id)init { if ((self = [super init])) { NSLog(@"Target created"); } return self; } - (void)dealloc { NSLog(@"Target destroyed"); [super dealloc]; } @end @implementation DOServer - (byref id)createTarget { return [[[DOTarget alloc] init] autorelease]; } @end int main() { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; DOServer *server = [[DOServer alloc] init]; NSConnection *connection = [[NSConnection new] autorelease]; [connection setRootObject:server]; if ([connection registerName:@"test-server"] == NO) { NSLog(@"Failed to vend server object"); } else [[NSRunLoop currentRunLoop] run]; [pool drain]; return 0; } Client.m #import <Foundation/Foundation.h> #import "Protocol.h" int main() { unsigned i = 0; for (; i < 3; i ++) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; id server = [NSConnection rootProxyForConnectionWithRegisteredName:@"test-server" host:nil]; [server setProtocolForProxy:@protocol(DOServer)]; NSLog(@"Created target: %@", [server createTarget]); [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:1.0]]; [pool drain]; } return 0; } The issue is that any remote objects created by the root proxy are not released when their proxy counterparts in the client go out of scope. According to the documentation: When an object’s remote proxy is deallocated, a message is sent back to the receiver to notify it that the local object is no longer shared over the connection. I would therefore expect that as each DOTarget goes out of scope (each time around the loop) it's remote counterpart would be dellocated, since there is no other reference to it being held on the remote side of the connection. In reality this does not happen: the temporary objects are only deallocate when the client application quits, or more accurately, when the connection is invalidated. I can force the temporary objects on the remote side to be deallocated by explicitly invalidating the NSConnection object I'm using each time around the loop and creating a new one but somehow this just feels wrong. Is this the correct behaviour from DO? Should all temporary objects live as long as the connection that created them? Are connections therefore to be treated as temporary objects which should be opened and closed with each series of requests against the server? Any insights would be appreciated.

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• Which programming language to choose? (for a specific problem/domain, details inside)

  - by Bijan

  I am building a trading portfolio management system that is responsible for production, optimization, and simulation of non-high frequency trading portfolios (dealing with 1min or 3min bars of data, not tick data). I plan on employing Amazon web services to take on the entire load of the application. I have four choices that I am considering as language. a) Java b) C++ c) C# d) Python Here is the scope of the extremes of the project scope. This isn't how it will be, maybe ever, but it's within the scope of the requirements: Weekly simulation of 10,000,000 trading systems. (Each trading system is expected to have its own data mining methods, including feature selection algorithms which are extremely computationally-expensive. Imagine 500-5000 features using wrappers. These are not run often by any means, but it's still a consideration) Real-time production of portfolio w/ 100,000 trading strategies Taking in 1 min or 3 min data from every stock/futures market around the globe (approx 100,000) Portfolio optimization of portfolios with up to 100,000 strategies. (rather intensive algorithm) Speed is a concern, but I believe that Java can handle the load. I just want to make sure that Java CAN handle the above requirements comfortably. I don't want to do the project in C++, but I will if it's required. The reason C# is on there is because I thought it was a good alternative to Java, even though I don't like Windows at all and would prefer Java if all things are the same. Python - I've read somethings on PyPy and pyscho that claim python can be optimized with JIT compiling to run at near C-like speeds.... That's pretty much the only reason it is on this list, besides that fact that Python is a great language and would probably be the most enjoyable language to code in, which is not a factor at all for this project, but a perk. To sum up: - real time production - weekly simulations of a large number of systems - weekly/monthly optimizations of portfolios - large numbers of connections to collect data from There is no dealing with millisecond or even second based trades. The only consideration is if Java can possibly deal with this kind of load when spread out of a necessary amount of EC2 servers. Thank you guys so much for your wisdom.

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• Continuous Form, how to add/update records with external connection

  - by Mohgeroth

  EDIT After some more research I found that I cannot use a continuous form with an unbound form since it can only reference a single record at a time. Given that I've altered my question... I have a sample form that pulls out data to enter into a table as an intermediary. Initially the form is unbound and I open connections to two main recordsets. I set the listbox's recordset equal to one of them and the forms recordset equal to the other. The problem is that I cannot add records or update existing ones. Attempting to key into the fields does nothing almost as if the field was locked (Which it is not). Settings of the recordsets are OpenKeyset and LockPessimistic. Tables are not linked, they come from an outside access database seperate from this project and must remain that way. I am using an adodb connection to get the data. Could the separation of the data from the project be causing this? Sample Code from the Form Option Compare Database Option Explicit Private conn As CRobbers_Connections Private exception As CError_Trapping Private mClient_Translations As ADODB.Recordset Private mUnmatched_Clients As ADODB.Recordset Private mExcluded_Clients As ADODB.Recordset //Construction Private Sub Form_Open(Cancel As Integer) Set conn = New CRobbers_Connections Set exception = New CError_Trapping Set mClient_Translations = New ADODB.Recordset Set mUnmatched_Clients = New ADODB.Recordset Set mExcluded_Clients = New ADODB.Recordset mClient_Translations.Open "SELECT * FROM Client_Translation" _ , conn.RBRS_Conn, adOpenKeyset, adLockPessimistic mUnmatched_Clients.Open "SELECT DISTINCT(a.Client) as Client" _ & " FROM Master_Projections a " _ & " WHERE Client NOT IN ( " _ & " SELECT DISTINCT ClientID " _ & " FROM Client_Translation);" _ , conn.RBRS_Conn, adOpenKeyset, adLockPessimistic mExcluded_Clients.Open "SELECT * FROM Clients_Excluded" _ , conn.RBRS_Conn, adOpenKeyset, adLockPessimistic End Sub //Add new record to the client translations Private Sub cmdAddNew_Click() If lstUnconfirmed <> "" Then AddRecord End If End Sub Private Function AddRecord() With mClient_Translations .AddNew .Fields("ClientID") = Me.lstUnconfirmed .Fields("ClientAbbr") = Me.txtTmpShort .Fields("ClientName") = Me.txtTmpLong .Update End With UpdateRecords End Function Private Function UpdateRecords() Me.lstUnconfirmed.Requery End Function //Load events (After construction) Private Sub Form_Load() Set lstUnconfirmed.Recordset = mUnmatched_Clients //Link recordset into listbox Set Me.Recordset = mClient_Translations End Sub //Destruction method Private Sub Form_Close() Set conn = Nothing Set exception = Nothing Set lstUnconfirmed.Recordset = Nothing Set Me.Recordset = Nothing Set mUnmatched_Clients = Nothing Set mExcluded_Clients = Nothing Set mClient_Translations = Nothing End Sub

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• How to stream semi-live audio over internet

  - by Thomas Tempelmann

  I want to write something like Skype, i.e. I have a constant audio stream on one computer and then recompress it in a format that's suitable for a latent internet connection, receive it on the other end and play it. Let's also assume that the internet connection is fairly modern and fast, i.e. DSL or alike, no slow connections over phone and such. The involved computers will also be rather modern (Dual Core Intel CPUs at 2GHz or more). I know how to handle the audio on the machines. What I don't know is how to transmit the audio in an efficient way. The challenges are: I'd like get good audio quality across the line. The stream should be received without drops. The stream may, however, be received with a little delay (a second delay is acceptable). I imagine that the transport software could first determine the average (and max) latency, then start the stream and tell the receiver to wait for that max latency before starting to play the audio. With that, if the latency doesn't get any higher, the entire stream will be playable on the other side without stutter or drops. If, due to unexpected IP latencies or blockages, the stream does get cut off, I want to be able to notice this so that I can take actions (e.g. abort the stream) and eventually start a new transmission. What are my options if I want do use ready-made software for the compression and tranmission? I have no intention to write my own audio compression engine, really. OTOH, I plan to sell the solution in a vertical market, meaning I can afford a few dollars of license fees per copy, but not $100s. I guess the simplest solution would be to just open a TCP stream, send a few packets back and forth to determine their running time (or even use UDP for that), then use the results as the guide for my max latency value, then simply fire the audio data in its raw form (uncompressed 16 bit stereo), along with a timing code over the TCP connection. The receiver reads the data and plays it with the pre-determined delay. That might just work with the type of fast connection I expect. I just wonder if there are better solutions to reach this goal, with better performance (lower latency) and less data (compressed). BTW, I first try to implement this on OS X, but might want to do it on Windows, too, if it proves successful.

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• Which network protocol to use for lightweight notification of remote apps?

  - by Chris Thornton

  I have this situation.... Client-initiated SOAP 1.1 communication between one server and let's say, tens of thousands of clients. Clients are external, coming in through our firewall, authenticated by certificate, https, etc.. They can be anywhere, and usually have their own firewalls, NAT routers, etc... They're truely external, not just remote corporate offices. They could be in a corporate/campus network, DSL/Cable, even Dialup. Client uses Delphi (2005 + SOAP fixes from 2007), and the server is C#, but from an architecture/design standpoint, that shouldn't matter. Currently, clients push new data to the server and pull new data from the server on 15-minute polling loop. The server currently does not push data - the client hits the "messagecount" method, to see if there is new data to pull. If 0, it sleeps for another 15 min and checks again. We're trying to get that down to 7 seconds. If this were an internal app, with one or just a few dozen clients, we'd write a cilent "listener" soap service, and would push data to it. But since they're external, sit behind their own firewalls, and sometimes private networks behind NAT routers, this is not practical. So we're left with polling on a much quicker loop. 10K clients, each checking their messagecount every 10 seconds, is going to be 1000/sec messages that will mostly just waste bandwidth, server, firewall, and authenticator resources. So I'm trying to design something better than what would amount to a self-inflicted DoS attack. I don't think it's practical to have the server send soap messages to the client (push) as this would require too much configuration at the client end. But I think there are alternatives that I don't know about. Such as: 1) Is there a way for the client to make a request for GetMessageCount() via Soap 1.1, and get the response, and then perhaps, "stay on the line" for perhaps 5-10 minutes to get additional responses in case new data arrives? i.e the server says "0", then a minute later in response to some SQL trigger (the server is C# on Sql Server, btw), knows that this client is still "on the line" and sends the updated message count of "5"? 2) Is there some other protocol that we could use to "ping" the client, using information gathered from their last GetMessageCount() request? 3) I don't even know. I guess I'm looking for some magic protocol where the client can send a GetMessageCount() request, which would include info for "oh by the way, in case the answer changes in the next hour, ping me at this address...". Also, I'm assuming that any of these "keep the line open" schemes would seriously impact the server sizing, as it would need to keep many thousands of connections open, simultaneously. That would likely impact the firewalls too, I think. Is there anything out there like that? Or am I pretty much stuck with polling? TIA, Chris

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• Nested Transaction issues within custom Windows Service

  - by pdwetz

  I have a custom Windows Service I recently upgraded to use TransactionScope for nested transactions. It worked fine locally on my old dev machine (XP sp3) and on a test server (Server 2003). However, it fails on my new Windows 7 machine as well as on 2008 Server. It was targeting 2.0 framework; I tried targeting 3.5 instead, but it still fails. The strange part is really in how it fails; no exception is thrown. The service itself merely times out. I added tracing code, and it fails when opening the connection for Database lookup #2 below. I also enabled tracing for System.Transactions; it literally cuts out partway while writing the block for the failed connection. We ran a SQL trace, but only the first lookup shows up. I put in code traces, and it gets to the trace the line before the second lookup, but nothing after. I've had the same experience hitting two different SQL servers (both are SQL 2005 running on Server 2003). The connection string is utilizing a SQL account (not Windows integration). All connections are against the same database in this case, but given the nature of the code it is being escalated to MSDTC. Here's the basic code structure: TransactionOptions options = new TransactionOptions(); options.IsolationLevel = System.Transactions.IsolationLevel.ReadCommitted; using (TransactionScope scope = new TransactionScope(TransactionScopeOption.RequiresNew, options)) { // Database lookup #1 TransactionOptions options = new TransactionOptions(); options.IsolationLevel = Transaction.Current != null ? Transaction.Current.IsolationLevel : System.Transactions.IsolationLevel.ReadCommitted; using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Required, options)) { // Database lookup #2; fails on connection.Open() // Database save (never reached) scope.Complete();<br/> } scope.Complete();<br/> } My local firewall is disabled. The service normally runs using Network Service, but I also tried my user account (same results). The short of it is that I use the same general technique widely in my web applications and haven't had any issues. I pulled out the code and ran it fine within a local Windows Form application. If anyone has any additional debugging ideas (or, even better, solutions) I'd love to hear them.

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• mysql: can't set max_allowed_package to anything grater than 16MB

  - by sas

  I'm not sure if this is the right place to post these kind of questions, if it's not so, please (politely) let me know... :-) I need to save files greater than 16MB on a mysql database from a php site... I've already changed the c:\xampp\mysql\bin\my.cnf and set max_allowed_packet to 16 MB, and everything worked fine then I set it to 32 MB but there´s no way I can handle a file bigger than 16 MB I get the following error: 'MySQL server has gone away' (the same error I had when max_allowed_packet was set to 1MB) there must be some other setting that doesn´t allow me to handle files bigger than 16MB maybe the php client, I guess, but I don't know where to edit it this is the code I'm running when file.txt is smaller than 16.776.192 bytes long, it works fine, but if file.txt has 16.777.216 bytes i get the aforementioned error oh, and the field download.content is a longblob... $file = 'file.txt'; $file_handle = fopen( $file, 'r' ); $content = fread( $file_handle, filesize( $file ) ); fclose( $file_handle ); db_execute( 'truncate table download', true ); $sql = "insert into download( code, title, name, description, original_name, mime_type, size, content, user_insert_id, date_insert, user_update_id, date_update ) values ( 'new file', 'new file', 'sas.jpg', 'new file', '$file', 'mime', " . filesize( $file ) . ", '" . addslashes( $content ) . "', 0, " . db_char_to_sql( now_char(), 'datetime' ) . ", 0, " . db_char_to_sql( now_char(), 'datetime' ) . " )"; db_execute( $sql, true ); (the db_execute funcion just opens the connections and executes the sql stuff) running on windows XP sp2 server version: 5.0.67-community PHP Version 4.4.9 mysql client API version: 3.23.49 using: ApacheFriends XAMPP (Basispaket) version 1.6.8 that comes with + Apache 2.2.9 + MySQL 5.0.67 (Community Server) + PHP 5.2.6 + PHP 4.4.9 + PEAR + phpMyAdmin 2.11.9.2 ... this is part of the content of c:\xampp\mysql\bin\my.cnf # The MySQL server [mysqld] port= 3306 socket= "C:/xampp/mysql/mysql.sock" basedir="C:/xampp/mysql" tmpdir="C:/xampp/tmp" datadir="C:/xampp/mysql/data" skip-locking key_buffer = 16M # max_allowed_packet = 1M max_allowed_packet = 32M table_cache = 128 sort_buffer_size = 512K net_buffer_length = 8K read_buffer_size = 256K read_rnd_buffer_size = 512K myisam_sort_buffer_size = 8M

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• Hibernate Communications Link Failure in Restlet-Hibernate Based Java application powered by MySQL

  - by Vatsala

  Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?)

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• waiting for 2 different events in a single thread

  - by João Portela

  component A (in C++) - is blocked waiting for alarm signals (not relevant) and IO signals (1 udp socket). has one handler for each of these. component B (java) - has to receive the same information the component A udp socket receives. periodicaly gives instructions that should be sent through component A udp socket. How to join both components? it is strongly desirable that: the changes to attach component B to component A are minimal (its not my code and it is not very pleasent to mess with). the time taken by the new operations (usually communicating with component B) interfere very little with the usual processing time of component A - this means that if the operations are going to take a "some" time I would rather use a thread or something to do them. note: since component A receives udp packets more frequently that it has component B instructions to forward, if necessary, it can only forward the instructions (when available) from the IO handler. my initial ideia was to develop a component C (in C++) that would sit inside the component A code (is this called an adapter?) that when instanciated starts the java process and makes the necessary connections (that not so little overhead in the initialization is not a problem). It would have 2 stacks, one for the data to give component B (lets call it Bstack) and for the data to give component A (lets call it Astack). It would sit on its thread (lets call it new-thread) waiting for data to be available in Bstack to send it over udp, and listen on the udp socket to put data on the Astack. This means that the changes to component A are only: when it receives a new UDP packet put it on the Bstack, and if there is something on the Astack sent it over its UDP socket (I decided for this because this socket would only be used in the main thread). One of the problems is that I don't know how to wait for both of these events at the same time using only one thread. so my questions are: Do I really need to use the main thread to send the data over component A socket or can I do it from the new-thread? (I think the answer is no, but I'm not sure about race conditions on sockets) how to I wait for both events? boost::condition_variable or something similar seems the solution in the case of the stack and boost::asio::io_service io_service.run() seems like the thing to use for the socket. Is there any other alternative solution for this problem that I'm not aware of? Thanks for reading this long text but I really wanted you to understand the problem.

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• SOAP not fetches result in PHP for Mouzenidis travel

  - by ????? ????????????

  I try to get results from http://api.mouzenidis-travel.com/search/ServiceMainSearch.svc?Wsdl There is some methods to fetch data: GetCountries // fetch available country data GetCityDeparture(int countryID) //fetch available departure city data GetFilter(int countryId, List departureCityId) // fetch others filters // My PHP code: $client = new SoapClient("http://api.mouzenidis-travel.com/search/ServiceMainSearch.svc?Wsdl"); $countryList = $client-GetCountries(); // results below [0] => stdClass Object ( [Code] => GR [ID] => 29 [Name] => Греция [NameLat] => Greece ) [1] => stdClass Object ( [Code] => CZ [ID] => 6240 [Name] => Чехия [NameLat] => Czech Republic ) $cityDepObj = $client-GetCityDeparture(array('countryID'=29)); [0] => stdClass Object ( [Code] => MOW [GroupName] => Россия [GroupNameLat] => Россия [GroupOrder] => 4 [ID] => 1 [Name] => Москва [NameLat] => Moscow [CountryID] => 460 [IsDeparture] => 1 [RegionID] => 0 ) [1] => stdClass Object ( [Code] => [GroupName] => Россия [GroupNameLat] => Россия [GroupOrder] => 4 [ID] => 299 [Name] => Архангельск [NameLat] => Arkhangelsk [CountryID] => 460 [IsDeparture] => 1 [RegionID] => 0 ) . . . $client-GetFilter(array(29,array(1))); Fatal error: Uncaught SoapFault exception: [s:Client] No connections available ... I wrote to the Mouzendinis Tech Support, no results. What make I wrong?

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• Downloading large file with php

  - by Alessandro

  Hi, I have to write a php script to download potentially large files. The file I'm reporting here works fine most of the times. However, if the client's connection is slow the request ends (with status code 200) in the middle of the downloading, but not always at the very same point, and not at the very same time. I tried to overwrite some php.ini variables (see the first statements) but the problem remains. I don't know if it's relevant but my hosting server is SiteGround, and for simple static file requests, the download works fine also with slow connections. I've found Forced downloading large file with php but I didn't understand mario's answer. I'm new to web programming. So here's my code. <?php ini_set('memory_limit','16M'); ini_set('post_max_size', '30M'); set_time_limit(0); include ('../private/database_connection.php'); $downloadFolder = '../download/'; $fileName = $_POST['file']; $filePath = $downloadFolder . $fileName; if($fileName == NULL) { exit; } ob_start(); session_start(); if(!isset($_SESSION['Username'])) { // or redirect to login (remembering this download request) $_SESSION['previousPage'] = 'download.php?file=' . $fileName; header("Location: login.php"); exit; } if (file_exists($filePath)) { header('Content-Description: File Transfer'); header('Content-Type: application/octet-stream'); //header('Content-Disposition: attachment; filename='.$fileName); header("Content-Disposition: attachment; filename=\"$fileName\""); header('Content-Transfer-Encoding: binary'); header('Expires: 0'); header('Cache-Control: must-revalidate, post-check=0, pre-check=0'); //header('Pragma: public'); header('Content-Length: ' . filesize($filePath)); ob_clean(); flush(); // download // 1 // readfile($filePath); // 2 $file = @fopen($filePath,"rb"); if ($file) { while(!feof($file)) { print(fread($file, 1024*8)); flush(); if (connection_status()!=0) { @fclose($file); die(); } } @fclose($file); } exit; } else { header('HTTP/1.1 404 File not found'); exit; } ?>

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• Daemonize() issues on Debian

  - by djTeller

  Hi, I'm currently writing a multi-process client and a multi-treaded server for some project i have. The server is a Daemon. In order to accomplish that, i'm using the following daemonize() code: static void daemonize(void) { pid_t pid, sid; /* already a daemon */ if ( getppid() == 1 ) return; /* Fork off the parent process */ pid = fork(); if (pid < 0) { exit(EXIT_FAILURE); } /* If we got a good PID, then we can exit the parent process. */ if (pid > 0) { exit(EXIT_SUCCESS); } /* At this point we are executing as the child process */ /* Change the file mode mask */ umask(0); /* Create a new SID for the child process */ sid = setsid(); if (sid < 0) { exit(EXIT_FAILURE); } /* Change the current working directory. This prevents the current directory from being locked; hence not being able to remove it. */ if ((chdir("/")) < 0) { exit(EXIT_FAILURE); } /* Redirect standard files to /dev/null */ freopen( "/dev/null", "r", stdin); freopen( "/dev/null", "w", stdout); freopen( "/dev/null", "w", stderr); } int main( int argc, char *argv[] ) { daemonize(); /* Now we are a daemon -- do the work for which we were paid */ return 0; } I have a strange side effect when testing the server on Debian (Ubuntu). The accept() function always fail to accept connections, the pid returned is -1 I have no idea what causing this, since in RedHat & CentOS it works well. When i remove the call to daemonize(), everything works well on Debian, when i add it back, same accept() error reproduce. I've been monitring the /proc//fd, everything looks good. Something in the daemonize() and the Debian release just doesn't seem to work. (Debian GNU/Linux 5.0, Linux 2.6.26-2-286 #1 SMP) Any idea what causing this? Thank you

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• Incorrect string encodings

  - by James

  Note: I have read all of the related PHP, UTF-8, character encoding articles that are usually suggested, but my question relates to data inserted before I applied such techniques. I am wishing to retrospectively fix all character encoding problems. Now all connections are set as utf8 using PDO. PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8' Unfortunately, a large amount of data was inserted that is of questionable encoding before I had implemented correct character encoding practices. As displayed by: $sql = "SELECT name FROM data LIMIT 3"; foreach ($pdo->query($sql) as $row) { $name = $row['name']; echo $name . "\n"; echo utf8_encode($name) . "\n"; echo utf8_decode($name) . "\n"; echo htmlspecialchars($name, ENT_QUOTES, 'UTF-8') . "\n"; echo htmlspecialchars(utf8_encode($name), ENT_QUOTES, 'UTF-8') . "\n"; echo htmlspecialchars(utf8_decode($name), ENT_QUOTES, 'UTF-8') . "\n"; echo '<hr/>'; } Which produces: Antonín Dvořák AntonÃÆín DvoÃâ¦Ãâ¢ÃÆák Anton??­n Dvo??????¡k Antonín Dvořák AntonÃÆín DvoÃâ¦Ãâ¢ÃÆák ---------- Ô±Ö€Õ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿Ö€ÕµÕ¡Õ¶ ñÃâ¬Ã¡Ã´ ýáùáÿÃâ¬ÃµÃ¡Ã¶ ????? ?????????? Ô±Ö€Õ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿Ö€ÕµÕ¡Õ¶ ñÃâ¬Ã¡Ã´ ýáùáÿÃâ¬ÃµÃ¡Ã¶ ---------- Tiësto Tiësto Tiësto Tiësto Tiësto Tiësto ---------- When removing 'SET NAMES utf8' with PDO it produces the data: Antonín DvoÅák Antonín DvoÃÂák Antonín Dvorák Antonín DvoÅák Antonín DvoÃÂák Antonín Dvorák ---------- ???? ????????? Ô±ÖÕ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿ÖÕµÕ¡Õ¶ ???? ????????? ???? ????????? Ô±ÖÕ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿ÖÕµÕ¡Õ¶ ???? ????????? ---------- Tiësto Tiësto Ti?sto Tiësto Tiësto ---------- And here is a dump of the database rows concerned: DROP TABLE IF EXISTS `data`; CREATE TABLE IF NOT EXISTS `data` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(80) NOT NULL, PRIMARY KEY (`id`), KEY `name` (`name`(10)), ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=0; INSERT INTO `data` (`id`, `name`) VALUES (0, 'Antonín Dvořák'), (1, 'Ô±Ö€Õ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿Ö€ÕµÕ¡Õ¶'), (2, 'Tiësto'); The 3rd and 6th lines of the 3rd row "Tiësto" are then correctly echoed. I'm just unsure what is the best way to correct encodings/detect the encodings of bad strings and correct, etc.

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