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• Opera Mobile, offline web app development, and memory

  - by Jake Krohn

  I'm developing a data collection app for use on a HP iPAQ 211. I'm doing it as an offline web app (go with what you know) using Opera Mobile 9.7 and Google Gears. Being it is an offline app, it is very dependent on Javascript for much of its behavior. I'm using the LocalServer, Database, and Geolocation components of Gears, as well as the JQuery core and a couple of plugins for form validation and other usability tweaks (no jQuery UI). I've tried to be conservative with my programming style and free up or close resources whenever possible, but Opera just slowly dies after about 10-20 minutes of use. The Javascript engine stops responding, pages only half-load, and eventually stop loading completely. I'm guessing it's a resource issue. Quitting and relaunching the browser solves the problem, but only temporarily. The iPAQ ships with 128 MB of RAM, about 85-87 MB of which is available immediately after a reset. With only Opera running, there still remains about 50 MB that is left unused. My questions are thus: Is it possible to get Opera to address this unused RAM? Are there configuration settings in Opera or in the Windows Registry itself that will help improve performance? I know where to tweak, but the descriptions of the opera:config variables that I've found are less than helpful. Is is laughable to ask about memory management and jQuery in the same sentence? If not, does anyone have any suggestions? Finally, are my plans too ambitious, given the platform I have to work with? I know that Gears and Windows Mobile 6 are on their way out, but they (theoretically) suffice for what I need to do. I could ditch them in favor of an iPhone/iPod Touch, Mobile Safari, and HTML5 but I'd like to try to make this work first. I didn't think that Opera was a dog when it comes to JS performance, but perhaps it's worse than I thought. That this motley collection of technologies works at all is a minor miracle, but it needs to be faster and more stable. I appreciate any suggestions.

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• How does Google Friend Connect accomplish cross domain communication without needing to upload a file to the client domain?

  - by mboyle

  Previously, Google's Friend Connect required users to upload a couple of files to their websites to enable cross domain communication and Facebook Connect still requires you to upload a single file to enabled it. Now, Friend Connect doesn't require any file upload... I was wondering how they were able to accomplish this. Reference: http://www.techcrunch.com/2009/10/02/easy-does-it-google-friend-connect-one-ups-facebook-connects-install-wizard/

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• WSIT, Maven, and wsimport -- Can They Work Together?

  - by rtperson

  Hi all, I'm working on a small-ish multi-module project in Maven. We've separated the UI from the database layer using Web Services, and thanks to the jaxws-maven-plugin, the creation of the WSDL and WS client are more or less handled for us. (The plugin is essentially a wrapper around wsgen and wsimport.) So far so good. The problem comes when I try to layer WSIT security into the picture. NetBeans allows me to generate the security metadata easily, but wsimport seems completely incapable of dealing with anything beyond a Basic-auth level of security. Here's our current, insecure way of calling wsimport during a Maven build: <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>jaxws-maven-plugin</artifactId> <version>1.10</version> <executions> <execution> <goals> <goal>wsimport</goal> </goals> <configuration> <wsdlUrls> <wsdlUrl>${basedir}/../WebService/target/jaxws/wsgen/wsdl/WebService.wsdl</wsdlUrl> </wsdlUrls> <packageName>com.yourcompany.appname.ws.client</packageName> <sourceDestDir>${basedir}/src/main/java</sourceDestDir> <destDir>${basedir}/target/jaxws</destDir> </configuration> </execution> </executions> </plugin> I have tried playing around with xauthFile, xadditionalHeaders, passing javax.xml.ws.security.auth.username and password through args. I have also tried using wsimport from the command line to point to the Tomcat-generated WSDL, which has the additional security info. Nothing, however, seems to change the composition of the wsimport-generated files at all. So I guess my question here is, to get a WSIT-compliant client, am I stuck abandoning Maven and the jaxws plugin altogether? Is there a way to get a WSIT client to auto-generate? Or will I need to generate the client by hand? Let me know if you need any additional info beyond what I've written here. I'm deploying to Tomcat, although that doesn't seem to be an issue, as Maven seems happy to pull Metro into the deployed WAR file. Thanks in advance!

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• .NET SerialPort DataReceived event thread interference with main thread

  - by Kiran

  I am writing a serial communication program using the SerialPort class in C# to interact with a strip machine connected via a RS232 cable. When i send the command to the machine it responds with some bytes depending on the command. Like when i send a "\D" command, i am expecting to download the machine program data of 180 bytes as a continous string. As per the machine's manual, it suggests as a best practice to send an unreognized characters like comma (,) character to make sure the machine is initialized before sending the first command in the cycle. My serial communication code is as follows: public class SerialHelper { SerialPort commPort = null; string currentReceived = string.Empty; string receivedStr = string.Empty; private bool CommInitialized() { try { commPort = new SerialPort(); commPort.PortName = "COM1"; if (!commPort.IsOpen) commPort.Open(); commPort.BaudRate = 9600; commPort.Parity = System.IO.Ports.Parity.None; commPort.StopBits = StopBits.One; commPort.DataBits = 8; commPort.RtsEnable = true; commPort.DtrEnable = true; commPort.DataReceived += new SerialDataReceivedEventHandler(commPort_DataReceived); return true; } catch (Exception ex) { return false; } } void commPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { SerialPort currentPort = (SerialPort)sender; currentReceived = currentPort.ReadExisting(); receivedStr += currentReceived; } internal int CommIO(string outString, int outLen, ref string inBuffer, int inLen) { receivedStr = string.Empty; inBuffer = string.Empty; if (CommInitialized()) { commPort.Write(outString); } System.Threading.Thread.Sleep(1500); int i = 0; while ((receivedStr.Length < inLen) && i < 10) { System.Threading.Thread.Sleep(500); i += 1; } if (!string.IsNullOrEmpty(receivedStr)) { inBuffer = receivedStr; } commPort.Close(); return inBuffer.Length; } } I am calling this code from a windows form as follows: len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) If(inBuffer == "!?*O") { len = SerialHelperObj.CommIO("\D",2,ref inBuffer, 180) } A valid return value from the serial port looks like this: \D00000010000000000010 550 3250 0000256000 and so on ... I am getting some thing like this: \D00000010D,, 000 550 D,, and so on... I feel that my comm calls are getting interferred with the one when i send commands. But i am trying to make sure the result of the comma command then initiating the actual command. but the received thread is inserting the bytes from the previous communication cycle. Can any one please shed some light into this...? I lost quite some hair just trying to get this work. I am not sure where i am doing wrong

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• SQL server timeout 2000 from C# .NET

  - by Johnny Egeland

  I have run into a strange problem using SQL Server 2000 and two linked server. For two years now our solution has run without a hitch, but suddenly yesterday a query synchronizing data from one of the databases to the other started timing out. I connect to a server in the production network, which is linked to a server containing orders I need data from. The query contains a few joins, but basically this summarizes what is done: INSERT INTO ProductionDataCache (column1, column2, ...) SELECT tab1.column1, tab1.column2, tab2.column1, tab3.column1 ... FROM linkedserver.database.dbo.Table1 AS tab1 JOIN linkedserver.database.dbo.Table2 AS tab2 ON (...) JOIN linkedserver.database.dbo.Tabl32 AS tab3 ON (...) ... WHERE tab1.productionOrderId = @id ORDER BY ... Obviously my first attempt to fix the problem was to increase the timeout limit from the original 5 minutes. But when I arrived at 30 minutes and still got a timeout, I started to suspect something else was going on. A query just does not go from executing in less than 5 minutes to over 30 minutes over night. I outputted the SQL query (which was originally in the C# code) to my logs, and decided to execute the query in the Query Analyzer directly on the database server. To my big surprise, the query executed correctly in less than 10 seconds. So I isolated the SQL execution in a simple test program, and observed the same query time out both on the server originally running this solution AND when running it locally on the database server. Also I have tried to create a Stored Procedure and execute this from the program, but this also times out. Running it in Query Analyzer works fine in less than a few seconds. It seems that the problem only occurs when I execute this query from the C# program. Has anyone seen such behavior before, and found a solution for it? UPDATE: I have now used SQL Profiler on the server. The obvious difference is that when executing the query from the .NET program, it shows up in the log as "exec sp_executesql N'INSERT INTO ...'", but when executing from Query Analyzer it occurs as a normal query in the log. Further I tried to connect the SQL Query Analyzer using the same SQL user as the program, and this triggered the problem in Query Analyzer as well. So it seems the problem only occurs when connecting via TCP/IP using a sql user.

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• CSS: background image does not fill when scrolling

  - by rekindleMyLoveOf

  Hi, working on a very small site which loads in one go, so there is a div which holds all the background images, and on top of that (i.e. higher z-index) there is a content div which holds everything. I can switch backgrounds easily based on what content is selected. Unfortunately, I noticed if you launch in a small window so that scrollbars appear, if you scroll there is no background image in the 'revealed' portions of the page. :-( Page structure: <body> <div id="bg"> <div class="bgone"></div> <div class="bgtwo"></div> </div> <div id="container"> <!-- content panels here --> </div> </body> css: #bg { margin: 0px; position: absolute; top: 0px; left: 0px; width:100%; height: 1024px; z-index:1; } .bgone { margin: 0px; position: absolute; width:100%; height: 1024px; background-image:url(../images/one.jpg); background-position:top; background-repeat:repeat-x; z-index:2; } .bgtwo { margin: 0px; position: absolute; width:100%; height: 1024px; background-image:url(../images/two.jpg); background-position:top; background-repeat:repeat-x; z-index:3; } #container { position:relative; width:900px; padding:0px; margin:0px auto; height:600px; z-index:10; }

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• Can someone please help, I cant get this simple scolling feature

  - by localgamer

  I want to be able to have many button and objects in my project but they all wont fit on the screen at once so i would like the user to be able to scroll down and have more appear but i cant get it to work. I tried using ScrollView but it always throws me errors. Here is what I have so far. Please, any help would be great. <?xml version="1.0" encoding="utf-8"?> <AbsoluteLayout android:id="@+id/widget0" android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Hello World, tipcalc" /> <TextView android:id="@+id/widget28" android:layout_width="99px" android:layout_height="17px" android:text="Monthly Income" android:layout_x="40px" android:layout_y="32px" > </TextView> <TextView android:id="@+id/widget29" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Cable" android:layout_x="40px" android:layout_y="82px" > </TextView> <TextView android:id="@+id/widget30" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Internet" android:layout_x="40px" android:layout_y="132px" > </TextView> <TextView android:id="@+id/widget33" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Total To Pay" android:layout_x="40px" android:layout_y="302px" > </TextView> <Button android:id="@+id/btncalculate" android:layout_width="87px" android:layout_height="wrap_content" android:text="Calculate" android:layout_x="40px" android:layout_y="182px" > </Button> <Button android:id="@+id/btnreset" android:layout_width="86px" android:layout_height="wrap_content" android:text="Reset" android:layout_x="140px" android:layout_y="182px" > </Button> <EditText android:id="@+id/Monthly" android:layout_width="wrap_content" android:layout_height="35px" android:text="100" android:textSize="18sp" android:layout_x="200px" android:layout_y="22px" > </EditText> <EditText android:id="@+id/Internet" android:layout_width="51px" android:layout_height="36px" android:text="10" android:textSize="18sp" android:layout_x="200px" android:layout_y="72px" > </EditText> <EditText android:id="@+id/Cable" android:layout_width="wrap_content" android:layout_height="39px" android:text="1" android:textSize="18sp" android:layout_x="200px" android:layout_y="122px" > </EditText> <TextView android:id="@+id/txttotal" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="" android:layout_x="200px" android:layout_y="302px" > </TextView> </AbsoluteLayout>

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• How to use jquery to paginate json data?

  - by Pandiya Chendur

  My json Data looks like this {"Table" : [{"Emp_Id" : "3","Identity_No" : "","Emp_Name" : "Jerome","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Supervisior","Desig_Description" : "Supervisior of the Construction","SalaryBasis" : "Monthly","FixedSalary" : "25000.00"},{"Emp_Id" : "4","Identity_No" : "","Emp_Name" : "Mohan","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Acc ","Desig_Description" : "Accountant","SalaryBasis" : "Monthly","FixedSalary" : "200.00"},{"Emp_Id" : "5","Identity_No" : "","Emp_Name" : "Murugan","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Mason","Desig_Description" : "Mason","SalaryBasis" : "Weekly","FixedSalary" : "150.00"},{"Emp_Id" : "6","Identity_No" : "","Emp_Name" : "Ram","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Mason","Desig_Description" : "Mason","SalaryBasis" : "Weekly","FixedSalary" : "120.00"},{"Emp_Id" : "7","Identity_No" : "","Emp_Name" : "Raja","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Mason","Desig_Description" : "Mason","SalaryBasis" : "Weekly","FixedSalary" : "135.00"},{"Emp_Id" : "8","Identity_No" : "","Emp_Name" : "Raja kumar","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Mason Helper","Desig_Description" : "Mason Helper","SalaryBasis" : "Weekly","FixedSalary" : "105.00"},{"Emp_Id" : "9","Identity_No" : "","Emp_Name" : "Lakshmi","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Mason Helper","Desig_Description" : "Mason Helper","SalaryBasis" : "Weekly","FixedSalary" : "100.00"},{"Emp_Id" : "10","Identity_No" : "","Emp_Name" : "Palani","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Carpenter","Desig_Description" : "Carpenter","SalaryBasis" : "Weekly","FixedSalary" : "200.00"},{"Emp_Id" : "11","Identity_No" : "","Emp_Name" : "Annamalai","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Carpenter","Desig_Description" : "Carpenter","SalaryBasis" : "Weekly","FixedSalary" : "220.00"},{"Emp_Id" : "12","Identity_No" : "","Emp_Name" : "David","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Steel Fixer","Desig_Description" : "Steel Fixer","SalaryBasis" : "Weekly","FixedSalary" : "220.00"},{"Emp_Id" : "13","Identity_No" : "","Emp_Name" : "Chandru","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Steel Fixer","Desig_Description" : "Steel Fixer","SalaryBasis" : "Weekly","FixedSalary" : "220.00"},{"Emp_Id" : "14","Identity_No" : "","Emp_Name" : "Mani","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Steel Helper","Desig_Description" : "Steel Helper","SalaryBasis" : "Weekly","FixedSalary" : "175.00"},{"Emp_Id" : "15","Identity_No" : "","Emp_Name" : "Karthik","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Wood Fixer","Desig_Description" : "Wood Fixer","SalaryBasis" : "Weekly","FixedSalary" : "195.00"},{"Emp_Id" : "16","Identity_No" : "","Emp_Name" : "Bala","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Wood Fixer","Desig_Description" : "Wood Fixer","SalaryBasis" : "Weekly","FixedSalary" : "185.00"},{"Emp_Id" : "17","Identity_No" : "","Emp_Name" : "Tamil arasi","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Wood Helper","Desig_Description" : "Wood Helper","SalaryBasis" : "Weekly","FixedSalary" : "185.00"},{"Emp_Id" : "18","Identity_No" : "","Emp_Name" : "Perumal","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Cook","Desig_Description" : "Cook","SalaryBasis" : "Weekly","FixedSalary" : "105.00"},{"Emp_Id" : "19","Identity_No" : "","Emp_Name" : "Andiappan","Address" : "Madurai","Date_Of_Birth" : "","Desig_Name" : "Watchman","Desig_Description" : "Watchman","SalaryBasis" : "Weekly","FixedSalary" : "150.00"}]} There are 22 records in this json... How to paginate this json data 5 per page using jquery? EDIT: The above image is my summary view of employee list iterated using jquery var jsonObj = JSON.parse(HfJsonValue); for (var i = jsonObj.Table.length - 1; i >= 0; i--) { var employee = jsonObj.Table[i]; $('<div class="resultsdiv"><br /><span class="resultName">' + employee.Emp_Name + '</span><span class="resultfields" style="padding-left:100px;">Category&nbsp;:</span>&nbsp;<span class="resultfieldvalues">' + employee.Desig_Name + '</span><br /><br /><span id="SalaryBasis" class="resultfields">Salary Basis&nbsp;:</span>&nbsp;<span class="resultfieldvalues">' + employee.SalaryBasis + '</span><span class="resultfields" style="padding-left:25px;">Salary&nbsp;:</span>&nbsp;<span class="resultfieldvalues">' + employee.FixedSalary + '</span><span style="font-size:110%;font-weight:bolder;padding-left:25px;">Address&nbsp;:</span>&nbsp;<span class="resultfieldvalues">' + employee.Address + '</span></div>').insertAfter('#ResultsDiv'); } I get 22 records now it may grow how to paginate json date by using jquery pagination.. Any suggestion...

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• Problem with eager load polymorphic associations using Linq and NHibernate

  - by Voislav

  Is it possible to eagerly load polymorphic association using Linq and NH? For example: Company is base class, Department is inherited from Company, and Company has association Employees to the User (one-to-many) and also association to the Country (many-to-one). Here is mapping part related to inherited class (without User and Country classes): <class name="Company" discriminator-value="Company"> <id name="Id" type="int" unsaved-value="0" access="nosetter.camelcase-underscore"> <generator class="native"></generator> </id> <discriminator column="OrganizationUnit" type="string" length="10" not-null="true"/> <property name="Name" type="string" length="50" not-null="true"/> <many-to-one name="Country" class="Country" column="CountryId" not-null ="false" foreign-key="FK_Company_CountryId" access="field.camelcase-underscore" /> <set name="Departments" inverse="true" lazy="true" access="field.camelcase-underscore"> <key column="DepartmentParentId" not-null="false" foreign-key="FK_Department_DepartmentParentId"></key> <one-to-many class="Department"></one-to-many> </set> <set name="Employees" inverse="true" lazy="true" access="field.camelcase-underscore"> <key column="CompanyId" not-null="false" foreign-key="FK_User_CompanyId"></key> <one-to-many class="User"></one-to-many> </set> <subclass name="Department" extends="Company" discriminator-value="Department"> <many-to-one name="DepartmentParent" class="Company" column="DepartmentParentId" not-null ="false" foreign-key="FK_Department_DepartmentParentId" access="field.camelcase-underscore" /> </subclass> </class> I do not have problem to eagerly load any of the association on the Company: Session.Query<Company>().Where(c => c.Name == "Main Company").Fetch(c => c.Country).Single(); Session.Query<Company>().Where(c => c.Name == "Main Company").FetchMany(c => c.Employees).Single(); Also, I could eagerly load not-polymorphic association on the department: Session.Query<Department>().Where(d => d.Name == "Department 1").Fetch(d => d.DepartmentParent).Single(); But I get NullReferenceException when I try to eagerly load any of the polymorphic association (from the Department): Assert.Throws<NullReferenceException>(() => Session.Query<Department>().Where(d => d.Name == "Department 1").Fetch(d => d.Country).Single()); Assert.Throws<NullReferenceException>(() => Session.Query<Department>().Where(d => d.Name == "Department 1").FetchMany(d => d.Employees).Single()); Am I doing something wrong or this is not supported yet?

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• I get EXC_BAD_ACCESS when MaxConcurrentOperationCount > 1

  - by kudorgyozo

  Hello i am using NSOperationQueue to download images in the background. I have created a custom NSOperation to download the images. I put the images in table cells. The problem is if I do [operationQueue setMaxConcurrentOperationCount: 10] and i scroll down several cells the program crashes with EXC_BAD_ACCESS. Every time it crashes at the same place in the table. There are 3 cells one after the other which are for the same company and have the same logo so basically it should download the images 3 times. Every other time it works fine. - (void) main { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSURL *url = [[NSURL alloc] initWithString:self.imageURL]; debugLog(@"downloading image: %@", self.imageURL); //NSError *error = nil; NSData *data = [[NSData alloc] initWithContentsOfURL:url]; [url release]; UIImage *image = [[UIImage alloc] initWithData:data]; [data release]; if (image) { if (image.size.width != ICONWIDTH && image.size.height != ICONHEIGHT) { UIImage *resizedImage; CGSize itemSize = CGSizeMake(ICONWIDTH, ICONHEIGHT); UIGraphicsBeginImageContext(itemSize); CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height); [image drawInRect:imageRect]; resizedImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); self.theImage = resizedImage; } else { self.theImage = image; } [image release]; } [delegate didFinishDownloadingImage: self]; [pool release]; } This is how i handle downloading the images. If i comment out [delegate didFinishDownloadingImage: self]; in the function above it doesn't crash but of course it is useless. -(void) didFinishDownloadingImage:(ImageDownloadOperation *) imageDownloader { [self performSelectorOnMainThread: @selector(handleDidFinishDownloadingImage:) withObject: imageDownloader waitUntilDone: FALSE]; } -(void) handleDidFinishDownloadingImage:(ImageDownloadOperation *)imageDownloadOperation { NSArray *visiblePaths = [self.myTableView indexPathsForVisibleRows]; CompanyImgDownloaderState *stateObject = (CompanyImgDownloaderState *)[imageDownloadOperation stateObject]; if ([visiblePaths containsObject: stateObject.indexPath]) { //debugLog(@"didFinishDownloadingImage %@ %@", imageDownloader.theImage); UITableViewCell *cell = [self.myTableView cellForRowAtIndexPath: stateObject.indexPath]; UIImageView *imageView = (UIImageView *)[cell viewWithTag: 1]; if (imageDownloadOperation.theImage) { imageView.image = imageDownloadOperation.theImage; stateObject.company.icon = imageDownloadOperation.theImage; } else { imageView.image = [(TestWebServiceAppDelegate *)[[UIApplication sharedApplication] delegate] getCylexIcon]; stateObject.company.icon = [(TestWebServiceAppDelegate *)[[UIApplication sharedApplication] delegate] getCylexIcon]; } } }

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• Unable to get simple ruby on rails Search to work :/

  - by edu222

  I am new to RoR, any help would be greatly appreciated :) I have a basic scaffolding CRUD app to add customers. I am trying to search by first_name or last_name fields. The error that I am getting is: NoMethodError in Clientes#find You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.each Extracted source (around line #9): 6: <th>Apellido</th> 7: </tr> 8: 9: <% for cliente in @clientes %> 10: <tr> 11: <td><%=h cliente.client_name %></td> 12: <td><%=h cliente.client_lastname %></td> Application Trace C:/Rails/clientes/app/views/clientes/find.html.erb:9:in `_run_erb_app47views47clientes47find46html46erb' My find function in controllers/clientes_controlee.rb is: # Find def find @cliente = Cliente.find(:all, :conditions=>["client_name = ? OR client_lastname = ?", params[:search_string], params[:search_string]]) end My views/layouts clientes.html.erb form code fragment is: <span style="text-align: right"> <% form_tag "/clientes/find" do %> <%= text_field_tag :search_string %> <%= submit_tag "Search" %> <% end %> </span> The search template I created in views/clientes/find.html.erb: <h1>Listing clientes for <%= params[:search_string] %></h1> <table> <tr> <th>Nombre</th> <th>Apellido</th> </tr> <% for cliente in @clientes %> <tr> <td><%=h cliente.client_name %></td> <td><%=h cliente.client_lastname %></td> <td><%= link_to 'Mostrar', cliente %></td> <td><%= link_to 'Editar', edit_cliente_path(cliente) %></td> <td><%= link_to 'Eliminar', cliente, :confirm =>'Estas Seguro de que desear eliminar a este te cliente?', :method => :delete %></td> </tr> <% end %> </table> <%= link_to 'Atras', clientes_path %

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• Code Golf - Banner Generation

  - by Claudiu

  When thanking someone, you don't want to just send them an e-mail saying "Thanks!", you want to have something FLASHY: Input: THANKS!! Output: TTT H H AAA N N K K SSS !!! !!! T H H A A NNN K K S !!! !!! T HHH AAA NNN KK SSS !!! !!! T H H A A N N K K S T H H A A N N K K SSS !!! !!! Write a program to generate a banner. You only have to generate upper-case A-Z along with spaces and exclamation points (what is a banner without an exclamation point?). All characters are made up of a 3x5 grid of the same character (so the S is a 3x5 grid made of S). All output should be on one row (so no newlines). Here are all the letters you need: Input: ABCDEFGHIJKL Output: AAA BBB CCC DD EEE FFF GGG H H III JJJ K K L A A B B C D D E F G H H I J K K L AAA BBB C D D EE FF G G HHH I J KK L A A B B C D D E F G G H H I J J K K L A A BBB CCC DD EEE F GGG H H III JJJ K K LLL Input: MNOPQRSTUVWX Output: M M N N OOO PPP QQQ RR SSS TTT U U V V W W X X MMM NNN O O P P Q Q R R S T U U V V W W X M M NNN O O PPP Q Q RR SSS T U U V V WWW X M M N N O O P QQQ R R S T U U V V WWW X M M N N OOO P QQQ R R SSS T UUU V WWW X X Input: YZ! Output: Y Y ZZZ !!! Y Y Z !!! YYY Z !!! Y Z YYY ZZZ !!! The winner is the shortest source code. Source code should read input from stdin, output to stdout. You can assume input will only contain [A-Z! ]. If you insult the user on incorrect input, you get a 10 character discount =P. I was going to require these exact 27 characters, but to make it more interesting, you can choose how you want them to look - whatever makes your code shorter! To prove that your letters do look like normal letters, show the output of the last three runs.

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• Connecting to MSSQL 2008 from Java

  - by Xinus

  I am trying to connect to MSSQL 2008 server from Java here is a program import java.sql.*; public class connectURL { public static void main(String[] args) { // Create a variable for the connection string. String connectionUrl = "jdbc:sqlserver://localhost/SQLEXPRESS/Databases/HelloWorld:1433;";// + //"databaseName=HelloWorld;integratedSecurity=true;"; // Declare the JDBC objects. Connection con = null; Statement stmt = null; ResultSet rs = null; try { // Establish the connection. Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); con = DriverManager.getConnection(connectionUrl); // Create and execute an SQL statement that returns some data. String SQL = "SELECT TOP 10 * FROM Person.Contact"; stmt = con.createStatement(); rs = stmt.executeQuery(SQL); // Iterate through the data in the result set and display it. while (rs.next()) { System.out.println(rs.getString(4) + " " + rs.getString(6)); } } // Handle any errors that may have occurred. catch (Exception e) { e.printStackTrace(); } finally { if (rs != null) try { rs.close(); } catch(Exception e) {} if (stmt != null) try { stmt.close(); } catch(Exception e) {} if (con != null) try { con.close(); } catch(Exception e) {} } } } But it shows error as com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host localhost/SQLEXPRESS/Databases/HelloWorld, port 1433 has failed. Error: "null. Verify the connection properties, check that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port, and that no firewall is blocking TCP connections to the port.". at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:170) at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(SQLServerConnection.java:1049) at com.microsoft.sqlserver.jdbc.SQLServerConnection.login(SQLServerConnection.java:833) at com.microsoft.sqlserver.jdbc.SQLServerConnection.connect(SQLServerConnection.java:716) at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(SQLServerDriver.java:841) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at connectURL.main(connectURL.java:43) I have given followed all the instructions as given in http://teamtutorials.com/database-tutorials/configuring-and-creating-a-database-in-ms-sql-2008 What can be the problem ?

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• UITableViewCells appear behind backgroundView

  - by Khanzor

  I am having a problem setting the background of UITableView to a UIImageView (see below for why I am doing this), once the view is set, it works fine, and scrolls with the UITableView, but it hides the elements of the Table View. I need to have a UIImageView as the background for a UITableView. I know this has been answered before, but the answers are to use: [UIColor colorWithPatternImage:[UIImage imageNamed:@"myImage.png"]]; Or something like (which I need to use): UIImageView *background = [MainWindow generateBackgroundWithFrame:tableView.bounds]; [tableView addSubview:background]; [tableView sendSubviewToBack:background]; The reason I need to use the latter is because of my generateBackgroundWithFrame method, which takes a large image, and draws a border around that image to the dimensions specified, and clips the remainder of the image: + (UIImageView *) generateBackgroundWithFrame: (CGRect)frame { UIImageView *background = [[[UIImageView alloc] initWithFrame:frame] autorelease]; background.image = [UIImage imageNamed:@"globalBackground.png"]; [background.layer setMasksToBounds:YES]; [background.layer setCornerRadius:10.0]; [background.layer setBorderColor:[[UIColor grayColor] CGColor]]; [background.layer setBorderWidth:3.0]; return background; } Please note: I understand that this might poorly effect performance, but I don't have the resources to go through and make those images for each potential screen in the app. Please do not answer this question with a mindless "you shouldn't do this" response. I am aware that it is possibly the wrong thing to do. How do I show my UITableView control elements? Is there something that I am doing wrong in my delegate? Here is a simplified version: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectMake(20, 20, 261, 45) reuseIdentifier:CellIdentifier] autorelease]; cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton; UIImage *rowBackground; NSString *imageName = @"standAloneTVButton.png"; rowBackground = [UIImage imageNamed:imageName]; UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(0, 5, 300, 200)]; textView.backgroundColor = [UIColor clearColor]; textView.textColor = [UIColor blackColor]; textView.font = [UIFont fontWithName:@"Helvetica" size:18.0f]; Purchase *purchase = [[PurchaseModel productsPurchased] objectAtIndex:indexPath.row]; textView.text = [purchase Title]; selectedTextView.text = textView.text; UIImageView *normalBackground = [[[UIImageView alloc] init] autorelease]; normalBackground.image = rowBackground; [normalBackground insertSubview:textView atIndex:0]; cell.backgroundView = normalBackground; [textView release]; } return cell; }

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• RIA Services Repository Save does not work!?

  - by Savvas Sopiadis

  Hello everybody! Doing my first SL4 MVVM RIA based application and i ran into the following situation: updating a record (EF4,NO-POCOS!!) in the SL-client seems to take place, but values in the dbms are unchanged. Debugging with Fiddler the message on save is (amongst others): EntityActions.nil? b9http://schemas.microsoft.com/2003/10/Serialization/Arrays^HasMemberChanges?^Id?^ Operation?Update I assume that this says only: hey! the dbms should do an update on this record, AND nothing more! Is that right?! I 'm using a generic repository like this: public class Repository<T> : IRepository<T> where T : class { IObjectSet<T> _objectSet; IObjectContext _objectContext; public Repository(IObjectContext objectContext) { this._objectContext = objectContext; _objectSet = objectContext.CreateObjectSet<T>(); } public IQueryable<T> AsQueryable() { return _objectSet; } public IEnumerable<T> GetAll() { return _objectSet.ToList(); } public IEnumerable<T> Find(Expression<Func<T, bool>> where) { return _objectSet.Where(where); } public T Single(Expression<Func<T, bool>> where) { return _objectSet.Single(where); } public T First(Expression<Func<T, bool>> where) { return _objectSet.First(where); } public void Delete(T entity) { _objectSet.DeleteObject(entity); } public void Add(T entity) { _objectSet.AddObject(entity); } public void Attach(T entity) { _objectSet.Attach(entity); } public void Save() { _objectContext.SaveChanges(); } } The DomainService Update Method is the following: [Update] public void UpdateCulture(Culture currentCulture) { if (currentCulture.EntityState == System.Data.EntityState.Detached) { this.cultureRepository.Attach(currentCulture); } this.cultureRepository.Save(); } I know that the currentCulture-Entity is detached. What confuses me (amongst other things) is this: is the _objectContext still alive? (which means it "will be"??? aware of the changes made to record, so simply calling Attach() and then Save() should be enough!?!?) What am i missing? Development Environment: VS2010RC - Entity Framework 4 (no POCOs) Thanks in advance

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• Run word on server for COM to work??

  - by chupinette

  I got this from php.net website. This is related to the problem I am having with tho code below. Can anyone explain me what the following does. I am using Vista. What does running Word on server implies? In order to get the Word example running, do the following on the server side. Worked for me... 1. Click START--RUN and enter "dcomcnfg" 2. In the "Applications" tab, go down to "Microsoft Word Document" 3. Click PROPERTIES button 4. Go to the "Security" Tab 5. Click "Use custom access permissions", and then click EDIT 6. Click ADD and then click SHOW USERS 7. Highlight the IIS anonymous user account (usually IUSR_), click ADD 8. Go back to the "Security" tab by hitting OK 9. Click "Use custom launch permissions", and the click EDIT 10. Click ADD and then click SHOW USERS 11. Highlight the IIS anonymous user account (usually IUSR_), click ADD 12. Hit OK, and then hit APPLY. Also, you should look at the "Identity" tab in the Microsoft Word Document PROPERTIES and see that it is set to "Interactive User" ALSO, log into the machine AS the IUSR_ account, start word, and make sure to click through the dialog boxes that Word shows the first time it is run for a certain user. In other words, make sure Word opens cleanly for the IUSR_ user. <?php // starting word $word = new COM("word.application") or die("Unable to instantiate Word"); echo "Loaded Word, version {$word->Version}\n"; //bring it to front $word->Visible = 1; //open an empty document $word->Documents->Add(); //do some weird stuff $word->Selection->TypeText("This is a test..."); $word->Documents[1]->SaveAs("Useless test.doc"); //closing word $word->Quit(); //free the object $word = null; ?>

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• point light illumination using Phong model

  - by Myx

  Hello: I wish to render a scene that contains one box and a point light source using the Phong illumination scheme. The following are the relevant code snippets for my calculation: R3Rgb Phong(R3Scene *scene, R3Ray *ray, R3Intersection *intersection) { R3Rgb radiance; if(intersection->hit == 0) { radiance = scene->background; return radiance; } ... // obtain ambient term ... // this is zero for my test // obtain emissive term ... // this is also zero for my test // for each light in the scene, obtain calculate the diffuse and specular terms R3Rgb intensity_diffuse(0,0,0,1); R3Rgb intensity_specular(0,0,0,1); for(unsigned int i = 0; i < scene->lights.size(); i++) { R3Light *light = scene->Light(i); R3Rgb light_color = LightIntensity(scene->Light(i), intersection->position); R3Vector light_vector = -LightDirection(scene->Light(i), intersection->position); // check if the light is "behind" the surface normal if(normal.Dot(light_vector)<=0) continue; // calculate diffuse reflection if(!Kd.IsBlack()) intensity_diffuse += Kd*normal.Dot(light_vector)*light_color; if(Ks.IsBlack()) continue; // calculate specular reflection ... // this I believe to be irrelevant for the particular test I'm doing } radiance = intensity_diffuse; return radiance; } R3Rgb LightIntensity(R3Light *light, R3Point position) { R3Rgb light_intensity; double distance; double denominator; if(light->type != R3_DIRECTIONAL_LIGHT) { distance = (position-light->position).Length(); denominator = light->constant_attenuation + (light->linear_attenuation*distance) + (light->quadratic_attenuation*distance*distance); } switch(light->type) { ... case R3_POINT_LIGHT: light_intensity = light->color/denominator; break; ... } return light_intensity; } R3Vector LightDirection(R3Light *light, R3Point position) { R3Vector light_direction; switch(light->type) { ... case R3_POINT_LIGHT: light_direction = position - light->position; break; ... } light_direction.Normalize(); return light_direction; } I believe that the error must be somewhere in either LightDirection(...) or LightIntensity(...) functions because when I run my code using a directional light source, I obtain the desired rendered image (thus this leads me to believe that the Phong illumination equation is correct). Also, in Phong(...), when I computed the intensity_diffuse and while debugging, I divided light_color by 10, I was obtaining a resulting image that looked more like what I need. Am I calculating the light_color correctly? Thanks.

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• groovy compile error

  - by Bunny Rabbit

  class x{ public static void main(String[] args){ String x="<html><head></head></html>"; String arr[]=x.split("<head>"); String script="hi"; x=arr[0]+"<head>"+script+arr[1]; System.out.println(x); } } the above code when compiled as a java file compiles fine but when used a s a groovy file spits the error : org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed: D:\Garage\groovy-binary-1.7.1\groovy-1.7.1\bin\x.groovy: 4: Apparent variable 'a rr' was found in a static scope but doesn't refer to a local variable, static fi eld or class. Possible causes: You attempted to reference a variable in the binding or an instance variable fro m a static context. You misspelled a classname or statically imported field. Please check the spelli ng. You attempted to use a method 'arr' but left out brackets in a place not allowed by the grammar. @ line 4, column 10. String arr[]=x.split(""); ^ D:\Garage\groovy-binary-1.7.1\groovy-1.7.1\bin\x.groovy: 6: Apparent variable 'a rr' was found in a static scope but doesn't refer to a local variable, static fi eld or class. Possible causes: You attempted to reference a variable in the binding or an instance variable fro m a static context. You misspelled a classname or statically imported field. Please check the spelli ng. You attempted to use a method 'arr' but left out brackets in a place not allowed by the grammar. @ line 6, column 5. x=arr[0]+""+script+arr[1]; ^ D:\Garage\groovy-binary-1.7.1\groovy-1.7.1\bin\x.groovy: 6: Apparent variable 'a rr' was found in a static scope but doesn't refer to a local variable, static fi eld or class. Possible causes: You attempted to reference a variable in the binding or an instance variable fro m a static context. You misspelled a classname or statically imported field. Please check the spelli ng. You attempted to use a method 'arr' but left out brackets in a place not allowed by the grammar. @ line 6, column 28. x=arr[0]+""+script+arr[1]; ^ 3 errors D:\Garage\groovy-binary-1.7.1\groovy-1.7.1\bin

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• Rich Text Editor (YUI Simple Text Editor used) not sending data to next page

  - by Aman Chhabra

  I am using a simple text editor from YUI, but when I click submit the code in the textarea/editor is not sent to the next page. I want to be able to receive it on the subsequent page and then store it in a DB(MySql). I have wasted lot of time already. Please help. HTML FILE: <html> <head> <script type="text/javascript" src="http://yui.yahooapis.com/combo?2.9.0/build/yahoo-dom-event/yahoo-dom-event.js&2.9.0/build/container/container_core-min.js&2.9.0/build/element/element-min.js&2.9.0/build/editor/simpleeditor-min.js"></script> <link rel="stylesheet" type="text/css" href="http://yui.yahooapis.com/2.9.0/build/editor/assets/skins/sam/simpleeditor.css" /> <link rel="stylesheet" type="text/css" href="http://yui.yahooapis.com/2.8.2r1/build/assets/skins/sam/skin.css"> <!-- Utility Dependencies --> <script src="http://yui.yahooapis.com/2.8.2r1/build/yahoo-dom-event/yahoo-dom-event.js"></script> <script src="http://yui.yahooapis.com/2.8.2r1/build/element/element-min.js"></script> <!-- Needed for Menus, Buttons and Overlays used in the Toolbar --> <script src="http://yui.yahooapis.com/2.8.2r1/build/container/container_core-min.js"></script> <script src="http://yui.yahooapis.com/2.8.2r1/build/menu/menu-min.js"></script> <script src="http://yui.yahooapis.com/2.8.2r1/build/button/button-min.js"></script> <!-- Source file for Rich Text Editor--> <script src="http://yui.yahooapis.com/2.8.2r1/build/editor/editor-min.js"></script> <script> YAHOO.util.Event.on('submit', 'click', function() { myEditor.saveHTML(); var html = myEditor.get('element').value; }); (function() { var Dom = YAHOO.util.Dom, Event = YAHOO.util.Event; var myConfig = { height: '200px', width: '900px', dompath: true, }; myEditor = new YAHOO.widget.SimpleEditor('msgpost', myConfig); myEditor.render(); })(); </script> </head> <body class="yui-skin-sam"> <form action="submit.php" method="post"> <textarea name="msgpost" id="msgpost" cols="50" rows="10"></textarea> <input type="submit" value="Submit" onsubmit="return myDoSubmit()"/> </form> </body> </html>

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• Drawing performance with CGImageCreateWithJPEGDataProvider?

  - by Rnegi

  I've actually curious about this for the iPhone. I am getting an MJPEG stream from a server and trying to render it natively on the iphone (without the use of safari class). Reasons for this is because the safari class while CAN render MJPEG natively, does not do so at the framerate I would like. So I tried drawing it natively, but I've come up with performance issues, namely a syncing issue between what I'm getting from the server and what I am able to draw onto the screen of the phone. (There should be a little lag, but the drift gets really bad, which is what I want to avoid). So I have a connection set up to my server and I do get the JPEGS. It's just data I insert into a NSMutableArray buffer CFMutableDataRef _t_data_ref = (CFMutableDataRef)[_buffer_array objectAtIndex:0]; //CGDataProviderRef imgDataProvider = CGDataProviderCreateWithCFData (_cf_buffer_data); CGDataProviderRef imgDataProvider = CGDataProviderCreateWithCFData(_t_data_ref); CGImageRef image = CGImageCreateWithJPEGDataProvider(imgDataProvider, NULL, true, kCGRenderingIntentDefault); CGImageRef imgRef = image; CGContextDrawImage(context, CGRectMake(0, 17, 380, 285), imgRef); CGImageRelease(image); CGDataProviderRelease(imgDataProvider); please note this is the gist of my code, but it should summarize what I am trying to accomplish with regards to drawing. Also in order to get the framerate in sync, I had to detach a separate thread that sleeps X seconds and calls [self setNeedsDisplay]. NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // Top-level pool while(1) { //[NSThread sleepForTimeInterval:TIMER_REFRESH_VALUE]; //sleep(unsigned int ); usleep(MICRO_REFRESH_VALUE); if ([_buffer_array count] > 10) { //NSLog(@"stuff %d", [_buffer_array count]); //[self setNeedsDisplay]; [self performSelectorOnMainThread:@selector(setNeedsDisplay) withObject:nil waitUntilDone:NO]; } } [pool release]; // Release the objects in the pool. My buffer of jpeg data actually fills up quite quick, but I can't seem to actually consume what i'm getting at the same rate, actually much slower. Are there any documents that can describe what kind of performance tuning I can do to make it go faster when rendering the JPEG to the screen? Or am I kind of stuck here? Thanks!

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• Blackberry Development, adding dynamic number of buttons and setting Fieldchangelistener() for them

  - by Nikesh Yadav

  Hi, I am adding dynamic number of buttons in a Blackberry application and trying to get different events on each button click. I am not able to apply the setchangelistener() for these array of buttons as once the loop finishes after adding all the buttons, the events gets generated only for the last indexed button. If I make us of getIndex(), it runs fine only if I am not adding any other fields on my screen, but if I add other fields along with these array of buttons, the getIndex() function count them in the indexing as well. Can anyone please help me out in setting FieldChangeListener to array of ButtonField? Here is a sample code of the way I am using the array of ButtonField. I the code I have added two test LabelField at the top of the screen, if I remove them the code will run fine and I will get different result for each button click, but if I keep them active, the indexing gets effected and the Button wont work. package buttonclickloop; import net.rim.device.api.ui.DrawStyle; import net.rim.device.api.ui.Field; import net.rim.device.api.ui.FieldChangeListener; import net.rim.device.api.ui.component.ButtonField; import net.rim.device.api.ui.component.LabelField; import net.rim.device.api.ui.container.HorizontalFieldManager; import net.rim.device.api.ui.container.MainScreen; public class ButtoncClickLoop extends MainScreen { int i = 0; private ButtonField[] btn = new ButtonField[50]; public ButtoncClickLoop() { // TODO Auto-generated constructor stub LabelField Field1 = new LabelField("Field1"); LabelField Field2 = new LabelField("Field2",DrawStyle.RIGHT | ButtonField.USE_ALL_WIDTH); HorizontalFieldManager FieldHmgr = new HorizontalFieldManager(); FieldHmgr.add(Field1); FieldHmgr.add(Field2); FieldHmgr.setMargin(0,0,10,5); add(FieldHmgr); while (i < 3){ FieldChangeListener listener = new FieldChangeListener() { public void fieldChanged(Field field, int context) { context = field.getIndex(); if (field == btn[context]){ add(new LabelField("Label" + context + "")); } } }; btn[i] = new ButtonField("Button" + i + ""); btn[i].setChangeListener(listener); add(btn[i]); i = i + 1; } } } Thanks, Nikesh

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• Asynchronous subprocess on Windows

  - by Stigma

  First of all, the overall problem I am solving is a bit more complicated than I am showing here, so please do not tell me 'use threads with blocking' as it would not solve my actual situation without a fair, FAIR bit of rewriting and refactoring. I have several applications which are not mine to modify, which take data from stdin and poop it out on stdout after doing their magic. My task is to chain several of these programs. Problem is, sometimes they choke, and as such I need to track their progress which is outputted on STDERR. pA = subprocess.Popen(CommandA, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE) # ... some more processes make up the chain, but that is irrelevant to the problem pB = subprocess.Popen(CommandB, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=pA.stdout ) Now, reading directly through pA.stdout.readline() and pB.stdout.readline(), or the plain read() functions, is a blocking matter. Since different applications output in different paces and different formats, blocking is not an option. (And as I wrote above, threading is not an option unless at a last, last resort.) pA.communicate() is deadlock safe, but since I need the information live, that is not an option either. Thus google brought me to this asynchronous subprocess snippet on ActiveState. All good at first, until I implement it. Comparing the cmd.exe output of pA.exe | pB.exe, ignoring the fact both output to the same window making for a mess, I see very instantaneous updates. However, I implement the same thing using the above snippet and the read_some() function declared there, and it takes over 10 seconds to notify updates of a single pipe. But when it does, it has updates leading all the way upto 40% progress, for example. Thus I do some more research, and see numerous subjects concerning PeekNamedPipe, anonymous handles, and returning 0 bytes available even though there is information available in the pipe. As the subject has proven quite a bit beyond my expertise to fix or code around, I come to Stack Overflow to look for guidance. :) My platform is W7 64-bit with Python 2.6, the applications are 32-bit in case it matters, and compatibility with Unix is not a concern. I can even deal with a full ctypes or pywin32 solution that subverts subprocess entirely if it is the only solution, as long as I can read from every stderr pipe asynchronously with immediate performance and no deadlocks. :)

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• What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

  - by Alex Dunlop

  Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outlined below? After experimenting on my own for a while (using ExecutorService and CyclicBarrier) and being somewhat surprised by the results, I would be grateful for some expert advice and maybe some new ideas. Existing questions here do not seem to focus primarily on performance, hence this new one. Thanks in advance! The core of the app is a simple iterative data processing algorithm, parallelized to the spread the computational load across 8 cores on a Mac Pro, running OS X 10.6 and Java 1.6.0_07. The data to be processed is split into 8 blocks and each block is fed to a Runnable to be executed by one of a fixed number of threads. Parallelizing the algorithm was fairly straightforward, and it functionally works as desired, but its performance is not yet what I think it could be. The app seems to spend a lot of time in system calls synchronizing, so after some profiling I wonder whether I selected the most appropriate synchronization mechanism(s). A key requirement of the algorithm is that it needs to proceed in stages, so the threads need to sync up at the end of each stage. The main thread prepares the work (very low overhead), passes it to the threads, lets them work on it, then proceeds when all threads are done, rearranges the work (again very low overhead) and repeats the cycle. The machine is dedicated to this task, Garbage Collection is minimized by using per-thread pools of pre-allocated items, and the number of threads can be fixed (no incoming requests or the like, just one thread per CPU core). V1 - ExecutorService My first implementation used an ExecutorService with 8 worker threads. The program creates 8 tasks holding the work and then lets them work on it, roughly like this: // create one thread per CPU executorService = Executors.newFixedThreadPool( 8 ); ... // now process data in cycles while( ...) { // package data into 8 work items ... // create one Callable task per work item ... // submit the Callables to the worker threads executorService.invokeAll( taskList ); } This works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as much as the processing algorithm would be expected to allow (some work items will finish faster than others, then idle). However, as the work items become smaller (and this is not really under the program's control), the user CPU load shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.8% 85% 1.30 64k 2.5% 77% 5.6 16k 4% 64% 22.5 4096 8% 56% 86 1024 13% 38% 227 256 17% 19% 420 64 19% 17% 948 16 19% 13% 1626 Legend: - block size = size of the work item (= computational steps) - system = system load, as shown in OS X Activity Monitor (red bar) - user = user load, as shown in OS X Activity Monitor (green bar) - cycles/sec = iterations through the main while loop, more is better The primary area of concern here is the high percentage of time spent in the system, which appears to be driven by thread synchronization calls. As expected, for smaller work items, ExecutorService.invokeAll() will require relatively more effort to sync up the threads versus the amount of work being performed in each thread. But since ExecutorService is more generic than it would need to be for this use case (it can queue tasks for threads if there are more tasks than cores), I though maybe there would be a leaner synchronization construct. V2 - CyclicBarrier The next implementation used a CyclicBarrier to sync up the threads before receiving work and after completing it, roughly as follows: main() { // create the barrier barrier = new CyclicBarrier( 8 + 1 ); // create Runable for thread, tell it about the barrier Runnable task = new WorkerThreadRunnable( barrier ); // start the threads for( int i = 0; i < 8; i++ ) { // create one thread per core new Thread( task ).start(); } while( ... ) { // tell threads about the work ... // N threads + this will call await(), then system proceeds barrier.await(); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; } public void run() { while( true ) { // wait for work barrier.await(); // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as before. However, as the work items become smaller, the load still shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.7% 78% 6.1 16k 5.5% 52% 25 4096 9% 29% 64 1024 11% 15% 117 256 12% 8% 169 64 12% 6.5% 285 16 12% 6% 377 For large work items, synchronization is negligible and the performance is identical to V1. But unexpectedly, the results of the (highly specialized) CyclicBarrier seem MUCH WORSE than those for the (generic) ExecutorService: throughput (cycles/sec) is only about 1/4th of V1. A preliminary conclusion would be that even though this seems to be the advertised ideal use case for CyclicBarrier, it performs much worse than the generic ExecutorService. V3 - Wait/Notify + CyclicBarrier It seemed worth a try to replace the first cyclic barrier await() with a simple wait/notify mechanism: main() { // create the barrier // create Runable for thread, tell it about the barrier // start the threads while( ... ) { // tell threads about the work // for each: workerThreadRunnable.setWorkItem( ... ); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; @NotNull volatile private Callable<Integer> workItem; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; this.workItem = NO_WORK; } final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { synchronized( this ) { workItem = callable; notify(); } } public void run() { while( true ) { // wait for work while( true ) { synchronized( this ) { if( workItem != NO_WORK ) break; try { wait(); } catch( InterruptedException e ) { e.printStackTrace(); } } } // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.4% 80% 6.3 16k 4.6% 60% 30.1 4096 8.6% 41% 98.5 1024 12% 23% 202 256 14% 11.6% 299 64 14% 10.0% 518 16 14.8% 8.7% 679 The throughput for small work items is still much worse than that of the ExecutorService, but about 2x that of the CyclicBarrier. Eliminating one CyclicBarrier eliminates half of the gap. V4 - Busy wait instead of wait/notify Since this app is the primary one running on the system and the cores idle anyway if they're not busy with a work item, why not try a busy wait for work items in each thread, even if that spins the CPU needlessly. The worker thread code changes as follows: class WorkerThreadRunnable implements Runnable { // as before final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { workItem = callable; } public void run() { while( true ) { // busy-wait for work while( true ) { if( workItem != NO_WORK ) break; } // do the work ... // wait for everyone else to finish barrier.await(); } } } Also works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.2% 81% 6.3 16k 4.2% 62% 33 4096 7.5% 40% 107 1024 10.4% 23% 210 256 12.0% 12.0% 310 64 11.9% 10.2% 550 16 12.2% 8.6% 741 For small work items, this increases throughput by a further 10% over the CyclicBarrier + wait/notify variant, which is not insignificant. But it is still much lower-throughput than V1 with the ExecutorService. V5 - ? So what is the best synchronization mechanism for such a (presumably not uncommon) problem? I am weary of writing my own sync mechanism to completely replace ExecutorService (assuming that it is too generic and there has to be something that can still be taken out to make it more efficient). It is not my area of expertise and I'm concerned that I'd spend a lot of time debugging it (since I'm not even sure my wait/notify and busy wait variants are correct) for uncertain gain. Any advice would be greatly appreciated.

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• sql: Group by x,y,z; return grouped by x,y with lowest f(z)

  - by Sai Emrys

  This is for http://cssfingerprint.com I collect timing stats about how fast the different methods I use perform on different browsers, etc., so that I can optimize the scraping speed. Separately, I have a report about what each method returns for a handful of URLs with known-correct values, so that I can tell which methods are bogus on which browsers. (Each is different, alas.) The related tables look like this: CREATE TABLE `browser_tests` ( `id` int(11) NOT NULL AUTO_INCREMENT, `bogus` tinyint(1) DEFAULT NULL, `result` tinyint(1) DEFAULT NULL, `method` varchar(255) DEFAULT NULL, `url` varchar(255) DEFAULT NULL, `os` varchar(255) DEFAULT NULL, `browser` varchar(255) DEFAULT NULL, `version` varchar(255) DEFAULT NULL, `created_at` datetime DEFAULT NULL, `updated_at` datetime DEFAULT NULL, `user_agent` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=33784 DEFAULT CHARSET=latin1 CREATE TABLE `method_timings` ( `id` int(11) NOT NULL AUTO_INCREMENT, `method` varchar(255) DEFAULT NULL, `batch_size` int(11) DEFAULT NULL, `timing` int(11) DEFAULT NULL, `os` varchar(255) DEFAULT NULL, `browser` varchar(255) DEFAULT NULL, `version` varchar(255) DEFAULT NULL, `user_agent` varchar(255) DEFAULT NULL, `created_at` datetime DEFAULT NULL, `updated_at` datetime DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=28849 DEFAULT CHARSET=latin1 (user_agent is broken down pre-insert into browser, version, and os from a small list of recognized values using regex; I keep the original user-agent string just in case.) I have a query like this that tells me the average timing for every non-bogus browser / version / method tuple: select c, avg(bogus) as bog, timing, method, browser, version from browser_tests as b inner join ( select count(*) as c, round(avg(timing)) as timing, method, browser, version from method_timings group by browser, version, method having c > 10 order by browser, version, timing ) as t using (browser, version, method) group by browser, version, method having bog < 1 order by browser, version, timing; Which returns something like: c bog tim method browser version 88 0.8333 184 reuse_insert Chrome 4.0.249.89 18 0.0000 238 mass_insert_width Chrome 4.0.249.89 70 0.0400 246 mass_insert Chrome 4.0.249.89 70 0.0400 327 mass_noinsert Chrome 4.0.249.89 88 0.0556 367 reuse_reinsert Chrome 4.0.249.89 88 0.0556 383 jquery Chrome 4.0.249.89 88 0.0556 863 full_reinsert Chrome 4.0.249.89 187 0.0000 105 jquery Chrome 5.0.307.11 187 0.8806 109 reuse_insert Chrome 5.0.307.11 123 0.0000 110 mass_insert_width Chrome 5.0.307.11 176 0.0000 231 mass_noinsert Chrome 5.0.307.11 176 0.0000 237 mass_insert Chrome 5.0.307.11 187 0.0000 314 reuse_reinsert Chrome 5.0.307.11 187 0.0000 372 full_reinsert Chrome 5.0.307.11 12 0.7500 82 reuse_insert Chrome 5.0.335.0 12 0.2500 102 jquery Chrome 5.0.335.0 [...] I want to modify this query to return only the browser/version/method with the lowest timing - i.e. something like: 88 0.8333 184 reuse_insert Chrome 4.0.249.89 187 0.0000 105 jquery Chrome 5.0.307.11 12 0.7500 82 reuse_insert Chrome 5.0.335.0 [...] How can I do this, while still returning the method that goes with that lowest timing? I could filter it app-side, but I'd rather do this in mysql since it'd work better with my caching.

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• Pointer to 2D array. Why does this example work?

  - by Louise

  I have this code example, but I don't understand why changing the values in the array inside outputUsingArray() are changing the original array. I would have expected changing the values of the array in outputUsingArray() would only be for a local copy of the array. Why isn't that so? However, this is the behaviour I would like, but I don't understand why it work. #include <stdlib.h> #include <stdio.h> void outputUsingArray(int array[][4], int n_rows, int n_cols) { int i, j; printf("Output Using array\n"); for (i = 0; i < n_rows; i++) { for (j = 0; j < n_cols; j++) { // Either can be used. //printf("%2d ", array[i][j] ); printf("%2d ", *(*(array+i)+j)); } printf("\n"); } printf("\n"); array[0][0] = 100; array[2][3] = 200; } void outputUsingPointer(int (*array)[4], int n_rows, int n_cols) { int i, j; printf("Output Using Pointer to Array i.e. int (*array)[4]\n"); for (i = 0; i < n_rows; i++) { for (j = 0; j < n_cols; j++) { printf("%2d ", *(*(array+i) + j )); } printf("\n"); } printf("\n"); } int main() { int array[3][4] = { { 0, 1, 2, 3 }, { 4, 5, 6, 7 }, { 8, 9, 10, 11 } }; outputUsingPointer((int (*)[4])array, 3, 4); outputUsingArray(array, 3, 4); printf("0,0: %i\n", array[0][0]); printf("2,3: %i\n", array[2][3]); return 0; }

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