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• Application log aggregation, management and notifications...

  - by Matthew Savage

  I'm wondering what everyone is using for logging, log management and log aggregation on their systems. I am working in a company which uses .NET for all it's applications and all systems are Windows based. Currently each application looks after its own logging and notifications of failures (e.g. if app A fails it will send out its own 'call for help' to an admin). While this current practice works its a bit hacky and hard to manage. I've been trying to find some options for making this work better and I've come up with the following: log4net & Chainsaw (ah, if it works). Logging via log4net or another framework into a central database & rolling our own management tool. Logging to the Windows event log and using MOM or System Center Operations Manager to aggregate and manage each of these servers & their apps. A hand-rolled solution to suck all the log files into one point and work some magic across them. Essentially what we are after is something which can pull log entries all together and allow for some analytics to be run across them, plus use a kind of event based system to, for example, send out a warning email when there have been 30+ warning level logs for an application in the last x minutes. So is there anything I've missed, or something someone else can suggest?

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• Is there a PHP benchmark that meets these specific criteria? [closed]

  - by Alex R

  I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The PHP source needs to be in a single file. It should solve a real-world problem. No silly looping over empty methods etc. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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• Game of life in F# with accelerator

  - by jpalmer

  I'm trying to write life in F# using accelerator v2, but for some odd reason my output isn't square despite all my arrays being square - It appears that everything but a rectangular area in the top left of the matrix is being set to false. I've got no idea how this could be happening as all my operations should treat the entire array equally. Any ideas? open Microsoft.ParallelArrays open System.Windows.Forms open System.Drawing type IPA = IntParallelArray type BPA = BoolParallelArray type PAops = ParallelArrays let RNG = new System.Random() let size = 1024 let arrinit i = Array2D.init size size (fun x y -> i) let target = new DX9Target() let threearr = new IPA(arrinit 3) let twoarr = new IPA(arrinit 2) let onearr = new IPA(arrinit 1) let zeroarr = new IPA(arrinit 0) let shifts = [|-1;-1|]::[|-1;0|]::[|-1;1|]::[|0;-1|]::[|0;1|]::[|1;-1|]::[|1;0|]::[|1;1|]::[] let progress (arr:BPA) = let sums = shifts //adds up whether a neighbor is on or not |> List.fold (fun (state:IPA) t ->PAops.Add(PAops.Cond(PAops.Rotate(arr,t),onearr,zeroarr),state)) zeroarr PAops.Or(PAops.CompareEqual(sums,threearr),PAops.And(PAops.CompareEqual(sums,twoarr),arr)) //rule for life let initrandom () = Array2D.init size size (fun x y -> if RNG.NextDouble() > 0.5 then true else false) type meform () as self= inherit Form() let mutable array = new BoolParallelArray(initrandom()) let timer = new System.Timers.Timer(1.0) //redrawing timer do base.DoubleBuffered <- true do base.Size <- Size(size,size) do timer.Elapsed.Add(fun _ -> self.Invalidate()) do timer.Start() let draw (t:Graphics) = array <- array |> progress let bmap = new System.Drawing.Bitmap(size,size) target.ToArray2D array |> Array2D.iteri (fun x y t -> if not t then bmap.SetPixel(x,y,Color.Black)) t.DrawImageUnscaled(bmap,0,0) do self.Paint.Add(fun t -> draw t.Graphics) do Application.Run(new meform())

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• Android AlertDialog clicking Positive and Negative just dismiss

  - by timmyg13

  Trying to have a sharedpreference where you click on it to restore default values, then an alert dialog comes up to ask if you are sure, but it is not doing anything, just dismissing the alertdialog. public class SettingsActivity extends PreferenceActivity implements OnSharedPreferenceChangeListener { /** Called when the activity is first created. */ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); c = this; addPreferencesFromResource(R.xml.settings); SharedPreferences sp = PreferenceManager .getDefaultSharedPreferences(this); sp.registerOnSharedPreferenceChangeListener(this); datasource = new PhoneNumberDataSource(this); Preference restore = (Preference) findPreference("RESTORE"); restore.setOnPreferenceClickListener(new OnPreferenceClickListener() { @Override public boolean onPreferenceClick(Preference preference) { createDialog(); return false; } }); } void createDialog() { Log.v("createDialog", ""); FrameLayout fl = new FrameLayout(c); AlertDialog.Builder b = new AlertDialog.Builder(c).setView(fl); b.setTitle("Restore Defaults?"); b.setPositiveButton("Restore", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface d, int which) { Log.v("restore clicked:", ""); } }); b.setNegativeButton("Cancel", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface d, int which) { Log.v("cancel clicked:", ""); d.dismiss(); } }).create(); b.show(); } } Neither the "cancel clicked" nor "restore clicked" show in the log. I do get a weird "W/InputManagerService(64): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@450317b8" in the log.

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• Java OutOfMemoryError message changes when trying to create Arrays of different sizes

  - by Gordon

  In the question by DKSRathore How to simulate the Out Of memory : Requested array size exceeds VM limit some odd behavior was noted when creating an arrays. When creating an array of size Integer.MAX_VALUE an exception with the error java.lang.OutOfMemoryError Requested array size exceeds VM limit was thrown. However when an array was created with a size less than the max but still above the virtual machine memory limit the error message read java.lang.OutOfMemoryError: Java heap space. Testing further I managed to narrow down where the error messages changes. long[] l = new long[2147483645]; exceptions message reads - Requested array size exceeds VM limit long[] l = new long[2147483644]; exceptions message reads - Java heap space errors I increased my virtual machine memory and still produced the same result. Has anyone any idea why this happens? Some extra info: Integer.MAX_VALUE = 2147483647. Edit: Here's the code I used to find the value, might be helpful. int max = Integer.MAX_VALUE; boolean done = false; while (!done) { try { max--; // Throws an error long[] l = new long[max]; // Exit if an error is no longer thrown done = true; } catch (OutOfMemoryError e) { if (!e.getMessage().contains("Requested array size exceeds VM limit")) { System.out.println("Message changes at " + max); done = true; } } }

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• How do I test database-related code with NUnit?

  - by Michael Haren

  I want to write unit tests with NUnit that hit the database. I'd like to have the database in a consistent state for each test. I thought transactions would allow me to "undo" each test so I searched around and found several articles from 2004-05 on the topic: http://weblogs.asp.net/rosherove/archive/2004/07/12/180189.aspx http://weblogs.asp.net/rosherove/archive/2004/10/05/238201.aspx http://davidhayden.com/blog/dave/archive/2004/07/12/365.aspx http://haacked.com/archive/2005/12/28/11377.aspx These seem to resolve around implementing a custom attribute for NUnit which builds in the ability to rollback DB operations after each test executes. That's great but... Does this functionality exists somewhere in NUnit natively? Has this technique been improved upon in the last 4 years? Is this still the best way to test database-related code? Edit: it's not that I want to test my DAL specifically, it's more that I want to test pieces of my code that interact with the database. For these tests to be "no-touch" and repeatable, it'd be awesome if I could reset the database after each one. Further, I want to ease this into an existing project that has no testing place at the moment. For that reason, I can't practically script up a database and data from scratch for each test.

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• OpenGL bitmap text fails after drawing polygon

  - by kaykun

  Hi, I'm using Win32 and OpenGL to to draw text onto a window. I'm using the bitmap font method, with wglUseFontBitmaps. Here is my main rendering function: glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glColor3f(1.0f, 0.0f, 1.0f); glBegin(GL_QUADS); glVertex2f(0.0f, 0.0f); glVertex2f(128.0f, 0.0f); glVertex2f(128.0f, 128.0f); glVertex2f(0.0f, 128.0f); glEnd(); glPopMatrix(); glPushMatrix(); glColor3f(1.0f, 1.0f, 1.0f); glRasterPos2i(200, 200); glListBase(fontList); glCallLists(5, GL_UNSIGNED_BYTE, "Test."); glPopMatrix(); SwapBuffers(hDC); As you can see it's very simple and the only thing that it's supposed to do is draw a quadrilateral and draw the text "Test.". But the problem is that drawing a polygon seems to mess up any text operations I try to do after it. If I place the text drawing functions before the polygon, both the text and the polygon draw fine. Is there something I'm missing here? Any help is appreciated.

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• Moving to .net 4 results in System.Transactions Critical: 0

  - by john

  Hi I have fully working project in .net 3.5SP1, with EF 1 ORM. I tried to upgrade to .net 4. No issue while upgrading... Then i ran the project and got a NullExecptionError, with no stack trace... and no way to debug. Looking at the output windows i can read this: System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>OTCSouscriptions.vshost.exe</AppDomain><Exception><ExceptionType>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Object reference not set to an instance of an object.</Message><StackTrace> at System.Windows.StyleHelper.GetInstanceValue(UncommonField`1 dataField, DependencyObject container, FrameworkElement feChild, FrameworkContentElement fceChild, Int32 childIndex, DependencyProperty dp, Int32 i, EffectiveValueEntry&amp;amp; entry) at System.Windows.FrameworkTemplate.ReceivePropertySet(Object targetObject, XamlMember member, Object value, DependencyObject templatedParent) at System.Windows.FrameworkTemplate.&amp;lt;&amp;gt;c__DisplayClass6.&amp;lt;LoadOptimizedTemplateContent&amp;gt;b__4(Object sender, XamlSetValueEventArgs setArgs) at System.Xaml.XamlObjectWriter.OnSetValue(Object eventSender, XamlMember member, Object value) at System.Xaml.XamlObjectWriter.Logic_ApplyPropertyValue(ObjectWriterContext ctx, XamlMember prop, Object value, Boolean onParent) at System.Xaml.XamlObjectWriter.Logic_DoAssignmentToParentProperty(ObjectWriterContext ctx) at System.Xaml.XamlObjectWriter.Logic_AssignProvidedValue(ObjectWriterContext ctx) at System.Xaml.XamlObjectWriter.WriteEndObject() at System.Xaml.XamlWriter.WriteNode(XamlReader reader) at System.Windows.FrameworkTemplate.LoadTemplateXaml(XamlReader templateReader, XamlObjectWriter currentWriter) Any help appreciated... Thanks John

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• Calling Java classes from IzPack

  - by bguiz

  I am trying to write an IzPack installer which is able to detect a previously installed version of the application. After finding out that it doesn't really support this feature, I think the only way to do this is through writing a Java class and calling it from IzPack. Tim Williscroft has previously suggested this method: <condition type="java" id="jbossEnv"> <java> <class>au.com.codarra.ela.installer.JBossChecker</class <field>hasJBossEnv</field> </java> <returnvalue type="boolean">true</returnvalue> </condition> However, is it possible to call <java> from somewhere other than a <condition> tag? I want to be able to call it from a <variable> tag. Also, is it possible to call a method from a Java class instead of reading a value of a field? I want to be able to pass parameters to my class. Thank you!

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• Parsing basic math equations for children's educational software?

  - by Simucal

  Inspired by a recent TED talk, I want to write a small piece of educational software. The researcher created little miniature computers in the shape of blocks called "Siftables". [David Merril, inventor - with Siftables in the background.] There were many applications he used the blocks in but my favorite was when each block was a number or basic operation symbol. You could then re-arrange the blocks of numbers or operation symbols in a line, and it would display an answer on another siftable block. So, I've decided I wanted to implemented a software version of "Math Siftables" on a limited scale as my final project for a CS course I'm taking. What is the generally accepted way for parsing and interpreting a string of math expressions, and if they are valid, perform the operation? Is this a case where I should implement a full parser/lexer? I would imagine interpreting basic math expressions would be a semi-common problem in computer science so I'm looking for the right way to approach this. For example, if my Math Siftable blocks where arranged like: [1] [+] [2] This would be a valid sequence and I would perform the necessary operation to arrive at "3". However, if the child were to drag several operation blocks together such as: [2] [\] [\] [5] It would obviously be invalid. Ultimately, I want to be able to parse and interpret any number of chains of operations with the blocks that the user can drag together. Can anyone explain to me or point me to resources for parsing basic math expressions? I'd prefer as much of a language agnostic answer as possible.

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• Flash "visible" issue

  - by justkevin

  I'm writing a tool in Flex that lets me design composite sprites using layered bitmaps and then "bake" them into a low overhead single bitmapData. I've discovered a strange behavior I can't explain: toggling the "visible" property of my layers works twice for each layer (i.e., I can turn it off, then on again) and then never again for that layer-- the layer stays visible from that point on. If I override "set visible" on the layer as such: override public function set visible(value:Boolean):void { if(value == false) this.alpha = 0; else {this.alpha = 1;} } The problem goes away and I can toggle "visibility" as much as I want. Any ideas what might be causing this? Edit: Here is the code that makes the call: private function onVisibleChange():void { _layer.visible = layerVisible.selected; changed(); } The changed() method "bakes" the bitmap: public function getBaked():BitmapData { var w:int = _composite.width + (_atmosphereOuterBlur * 2); var h:int = _composite.height + (_atmosphereOuterBlur * 2); var bmpData:BitmapData = new BitmapData(w,h,true,0x00000000); var matrix:Matrix = new Matrix(); var bounds:Rectangle = this.getBounds(this); matrix.translate(w/2,h/2); bmpData.draw(this,matrix,null,null,new Rectangle(0,0,w,h),true); return bmpData; } Incidentally, while the layer is still visible, using the Flex debugger I can verify that the layer's visible value is "false".

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• Complex derived attributes in Django models

  - by rabidpebble

  What I want to do is implement submission scoring for a site with users voting on the content, much like in e.g. reddit (see the 'hot' function in http://code.reddit.com/browser/sql/functions.sql). My submission model currently keeps track of up and down vote totals. Currently, when a user votes I create and save a related Vote object and then use F() expressions to update the Submission object's voting totals. The problem is that I want to update the score for the submission at the same time, but F() expressions are limited to only simple operations (it's missing support for log(), date_part(), sign() etc.) From my limited experience with Django I can see 4 options here: extend F() somehow (haven't looked at the code yet) to support the missing SQL functions; this is my preferred option and seems to fit within the Django framework the best define a scoring function (much like reddit's 'hot' function) in my database, and have Django use the value of that function for the value of the score field; as far as I can tell, #2 is not possible wrap my two step voting process in a suitably isolated transaction so that I can calculate the voting totals in Python and then update the Submission's voting totals without fear that another vote against the submission could be added/changed in the meantime; I'm hesitant to take this route because it seems overly complex - what is a "suitably isolated transaction" in this case anyway? use raw SQL; I would prefer to avoid this entirely -- what's the point of an ORM if I have to revert to SQL for such a common use case as this! (Note that this coming from somebody who loves sprocs, but is using Django for ease of development.) Before I embark on this mission to extend F() (which I'm not sure is even possible), am I about to reinvent the wheel? Is there a more standard way to do this? It seems like such a common use case and yet in an hour of searching I have yet to find a common solution...

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• Which Java library for Binary Decision Diagrams?

  - by reprogrammer

  A Binary Decision Diagram (BDD) is a data structure to represent boolean functions. I'd like use this data structure in a Java program. My search for Java based BDD libraries resulted into the following packages. Java Decision Diagram Libraries JavaBDD JDD If you know of any other BDD libraries available for Java programs, please let me know so that I add it to the list above. If you have used any of these libraries, please tell me about your experience with the library. In particular, I'd like you to compare the available libraries along the following dimensions. Quality. Is the library mature and reasonably bug free? Performance. How do you evaluate the performance of the library? Support. Could you easily get support whenever you encountered a problem with the library? Was the library well documented? Ease of use. Was the API well designed? Could you install and use the library quickly and easily? Please mention the version of the library that you are evaluating.

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• Pass a data.frame column name to a function

  - by Kevin Middleton

  I'm trying to write a function to accept a data.frame (x) and a column from it. The function performs some calculations on x and later returns another data.frame. I'm stuck on the best-practices method to pass the column name to the function. The two minimal examples fun1 and fun2 below produce the desired result, being able to perform operations on x$column, using max() as an example. However, both rely on the seemingly (at least to me) inelegant (1) call to substitute() and possibly eval() and (2) the need to pass the column name as a character vector. fun1 <- function(x, column){ do.call("max", list(substitute(x[a], list(a = column)))) } fun2 <- function(x, column){ max(eval((substitute(x[a], list(a = column))))) } df <- data.frame(A = 1:20, B = rnorm(10)) fun1(df, "B") fun2(df, "B") I would like to be able to call the function as fun(df, B), for example. Other options I have considered but have not tried: Pass column as an integer of the column number. I think this would avoid substitute(). Ideally, the function could accept either. with(x, get(column)), but, even if it works, I think this would still require substitute Make use of formula() and match.call(), neither of which I have much experience with. Subquestion: Is do.call() preferred over eval()? Thanks, Kevin

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• MySqlDataReader giving error at build

  - by TuxMeister

  Hey there. I have a function in VB.net that authenticates a user towards a MySQL DB before launching the main application. Here's the code of the function: Public Function authConnect() As Boolean Dim dbserver As String Dim dbuser As String Dim dbpass As String dbserver = My.Settings.dbserver.ToString dbuser = My.Settings.dbuser.ToString dbpass = My.Settings.dbpass.ToString conn = New MySqlConnection myConnString = "server=" & dbserver & ";" & "user id=" & dbuser & ";" & "password=" & dbpass & ";" & "database=rtadmin" Dim myCommand As New MySqlCommand Dim myAdapter As New MySqlDataAdapter Dim myData As New DataTable Dim myDataReader As New MySqlDataReader Dim query As String myCommand.Parameters.Add(New MySqlParameter("?Username", login_usr_txt.Text)) myCommand.Parameters.Add(New MySqlParameter("?Password", login_pass_txt.Text)) query = "select * from users where user = ?Username and passwd = ?Password" conn.ConnectionString = myConnString Try conn.Open() Try myCommand.Connection = conn myCommand.CommandText = query myAdapter.SelectCommand = myCommand myDataReader = myCommand.ExecuteReader If myDataReader.HasRows() Then MessageBox.Show("You've been logged in.", "RT Live! Information", MessageBoxButtons.OK, MessageBoxIcon.Information) End If Catch ex As Exception End Try Catch ex As Exception End Try End Function The function is not yet complete, there are a few other things that need to be done before launching the application, since I'm using a MessageBox to display the result of the login attempt. The error that I'm getting is the following: Error 1 'MySql.Data.MySqlClient.MySqlDataReader.Friend Sub New(cmd As MySql.Data.MySqlClient.MySqlCommand, statement As MySql.Data.MySqlClient.PreparableStatement, behavior As System.Data.CommandBehavior)' is not accessible in this context because it is 'Friend'. C:\Users\Mario\documents\visual studio 2010\Projects\Remote Techs Live!\Remote Techs Live!\Login.vb 43 13 Remote Techs Live! Any ideas? Thanks.

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• Diffie-Hellman -- Primitive root mod n -- cryptography question.

  - by somewhat confused

  In the below snippet, please explain starting with the first "for" loop what is happening and why. Why is 0 added, why is 1 added in the second loop. What is going on in the "if" statement under bigi. Finally explain the modPow method. Thank you in advance for meaningful replies. public static boolean isPrimitive(BigInteger m, BigInteger n) { BigInteger bigi, vectorint; Vector<BigInteger> v = new Vector<BigInteger>(m.intValue()); int i; for (i=0;i<m.intValue();i++) v.add(new BigInteger("0")); for (i=1;i<m.intValue();i++) { bigi = new BigInteger("" + i); if (m.gcd(bigi).intValue() == 1) v.setElementAt(new BigInteger("1"), n.modPow(bigi,m).intValue()); } for (i=0;i<m.intValue();i++) { bigi = new BigInteger("" + i); if (m.gcd(bigi).intValue() == 1) { vectorint = v.elementAt(bigi.intValue()); if ( vectorint.intValue() == 0) i = m.intValue() + 1; } } if (i == m.intValue() + 2) return false; else return true; }

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• Switch statement usage - C

  - by Jamie Keeling

  Hello, I have a thread function on Process B that contains a switch to perform certain operations based on the results of an event sent from Process A, these are stored as two elements in an array. I set the first element to the event which signals when Process A has data to send and I have the second element set to the event which indicates when Process A has closed. I have began to implement the functionality for the switch statement but I'm not getting the results as I expect. Consider the following: // //Thread function DWORD WINAPI ThreadFunc(LPVOID passedHandle) { for(i = 0; i < 2; i++) { ghEvents[i] = OpenEvent(EVENT_ALL_ACCESS, FALSE, TEXT("Global\\ProducerEvents")); if(ghEvents[i] == NULL) { getlasterror = GetLastError(); } } dwProducerEventResult = WaitForMultipleObjects( 2, ghEvents, FALSE, INFINITE); switch (dwProducerEventResult) { case WAIT_OBJECT_0 + 0: { //Producer sent data //unpackedHandle = *((HWND*)passedHandle); MessageBox(NULL,L"Test",L"Test",MB_OK); break; } case WAIT_OBJECT_0 + 1: { //Producer closed ExitProcess(1); break; } default: return; } } As you can see if the event in the first array is signalled Process B should display a simple message box, if the second array is signalled the application should close. When I actually close Process A, Process B displays the message box instead. If I leave the first case blank (Do nothing) both applications close as they should. Furthermore Process B sends data an error is thrown (When I comment out the unpacking): Have I implemented my switch statement incorrectly? I though I handled the unpacking of the HWND correctly too, any suggestions? Thanks for your time.

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• facebook: can't send email from app to user

  - by flybywire

  I can't send email to my app users, even though I have the permissions. I am working with the java library, although I don't think it is related to that. long uid = ...; Collection<Long> uids = new ArrayList<Long>(); uids.add(uid); FacebookXmlRestClient client = new FacebookXmlRestClient(api, secret); boolean sendEmailPerm = client.users_hasAppPermission(Permission.EMAIL,uid); System.out.println("Can send email: "+ sendEmailPerm); Collection<String> sent = client.notifications_sendTextEmail(uids, "subject", "body"); System.out.println("Succesfully sent email to: "+sent); sent = client.notifications_sendFbmlEmail(uids, "subject", "body"); System.out.println("Succesfully sent email to: "+sent); I am trying both with fbml and text email. I can also obtain the user's proxied_email property but when I send email to that address with my regular mail client is doesn't arrive. The output is: Can send email: true Succesfully sent email to: [] Succesfully sent email to: []

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• Fastest way to generate delimited string from 1d numpy array

  - by Abiel

  I have a program which needs to turn many large one-dimensional numpy arrays of floats into delimited strings. I am finding this operation quite slow relative to the mathematical operations in my program and am wondering if there is a way to speed it up. For example, consider the following loop, which takes 100,000 random numbers in a numpy array and joins each array into a comma-delimited string. import numpy as np x = np.random.randn(100000) for i in range(100): ",".join(map(str, x)) This loop takes about 20 seconds to complete (total, not each cycle). In contrast, consider that 100 cycles of something like elementwise multiplication (x*x) would take than one 1/10 of a second to complete. Clearly the string join operation creates a large performance bottleneck; in my actual application it will dominate total runtime. This makes me wonder, is there a faster way than ",".join(map(str, x))? Since map() is where almost all the processing time occurs, this comes down to the question of whether there a faster to way convert a very large number of numbers to strings.

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• A linked list with multiple heads in Java

  - by Emile

  Hi, I have a list in which I'd like to keep several head pointers. I've tried to create multiple ListIterators on the same list but this forbid me to add new elements in my list... (see Concurrent Modification exception). I could create my own class but I'd rather use a built-in implementation ;) To be more specific, here is an inefficient implementation of two basic operations and the one wich doesn't work : class MyList <E { private int[] _heads; private List<E _l; public MyList ( int nbHeads ) { _heads = new int[nbHeads]; _l = new LinkedList<E(); } public void add ( E e ) { _l.add(e); } public E next ( int head ) { return _l.get(_heads[head++]); // ugly } } class MyList <E { private Vector<ListIterator<E _iters; private List<E _l; public MyList ( int nbHeads ) { _iters = new Vector<ListIterator<E(nbHeads); _l = new LinkedList<E(); for( ListIterator<E iter : _iters ) iter = _l.listIterator(); } public void add ( E e ) { _l.add(e); } public E next ( int head ) { // ConcurrentModificationException because of the add() return _iters.get(head).next(); } } Emile

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• POSTing JSON data to WCF REST

  - by Randall Sexton

  I'm trying to send data from a client application using jQuery to a REST WCF service based on the WCF REST starter kit. Here's what I have so far. Service Definition: [WebHelp(Comment = "Save PropertyValues to the database")] [WebInvoke(Method = "POST", UriTemplate = "PropertyValues_Save", BodyStyle = WebMessageBodyStyle.WrappedRequest, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)] [OperationContract] public bool PropertyValues_Save(Guid assetId, Dictionary<Guid, string> newValues) { ... } Call from the client: $.ajax({ url:SVC_PROPERTYVALUES_SAVE, type: "POST", contentType: "application/json; charset=utf-8", data: jsonData, dataType: "json", error: function(XMLHttpRequest, textStatus, errorThrown) { alert(textStatus + ' ' + errorThrown); }, success: function(data) { if (data) { alert('Values saved'); $("#confirmSubmit").dialog('close'); } else { alert('Values failed to save'); $("#confirmSubmit").dialog('close'); } } }); Example of the JSON being passed: { "assetId": "d70714c3-e403-4cc5-b8a9-9713d05b2ee0", "newValues": [ { "key": "bd01aa88-b48d-47c7-8d3f-eadf47a46680", "value": "0e9fdf34-2d12-4639-8d70-19b88e753ab1" }, { "key": "06e8eda2-a004-450e-90ab-64df357013cf", "value": "1d490aec-f40e-47d5-865c-07fe9624f955" } ] } I'm using Windows Authentication on the virtual directory. When I call operations that are GETs, everything is fine. This code is prompting the browser to log in. When I enter my credentials, I simply get an alert in my browser which says "error undefined". Even if you can't help my specific error, do you see anything that looks wrong from glancing? I've been beating my head on this nearly all day. Thanks in advance.

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• Strange EListError occurance (when accessing variable-defined index)

  - by michal

  Hi, I have a TList which stores some objects. Now I have a function which does some operations on that list: function SomeFunct(const AIndex: integer): IInterface begin if (AIndex > -1) and (AIndex < fMgr.Windows.Count ) then begin if (fMgr.Windows[AIndex] <> nil) then begin if not Supports(TForm(fMgr.Windows[AIndex]), IMyFormInterface, result) then result:= nil; end; end else result:= nil; end; now, what is really strange is that accessing fMgr.Windows with any proper index causes EListError... However if i hard-code it (in example, replace AIndex with value 0 or 1) it works fine. I tried debugging it, the function gets called twice, with arguments 0 and 1 (as supposed). while AIndex = 0, evaluating fMgr.Windows[AIndex] results in EListError at $someAddress, while evaluating fMgr.Windws[0] instead - returns proper results ... what is even more strange, even though there is an EListError, the function returns proper data ... and doesn't show anything. Just info on two EListError memory leaks on shutdown (using FastMM) any ideas what could be wrong?! Thanks in advance michal

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• MVVM-Light EventToCommand Behavior for CheckBox Checked/Unchecked in Silverlight

  - by George Durzi

  I would like to handle the Checked and Unchecked events of a Checkbox control and execute a command in my ViewModel. I wired up an EventTrigger for both the Checked and Unchecked events as follows: <CheckBox x:Name="chkIsExtendedHr" IsChecked="{Binding Schedule.Is24Hour, Mode=TwoWay}"> <i:Interaction.Triggers> <i:EventTrigger EventName="Checked"> <GalaSoft_MvvmLight_Command:EventToCommand CommandParameter="{Binding IsChecked, ElementName=chkIsExtendedHr}" Command="{Binding Path=SetCloseTime, Mode=OneWay}" /> </i:EventTrigger> <i:EventTrigger EventName="Unchecked"> <GalaSoft_MvvmLight_Command:EventToCommand CommandParameter="{Binding IsChecked, ElementName=chkIsExtendedHr}" Command="{Binding Path=SetCloseTime, Mode=OneWay}" /> </i:EventTrigger> </i:Interaction.Triggers> </CheckBox> I defined a RelayCommand in my ViewModel and wired up an action for it: public RelayCommand<Boolean> SetCloseTime{ get; private set; } ... SetCloseTime= new RelayCommand<bool>(ExecuteSetCloseTime); The parameter in the action for the command always resolves to the previous state of the CheckBox, e.g. false when the CheckBox is checked, and true when the CheckBox is unchecked. void ExecuteSetCloseTime(bool isChecked) { if (isChecked) { // do something } } Is this expected behavior? I have a workaround where I have separate triggers (and commands) for the Checked and Unchecked and use a RelayCommand instead of RelayCommand<bool>. Each command executes correctly when the CheckBox is checked and unchecked. Feels a little dirty though - even dirtier than having UI code in my ViewModel :) Thanks

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• Understanding F# Asynchronous Programming

  - by Yin Zhu

  I kind of know the syntax of asynchronous programming in F#. E.g. let downloadUrl(url:string) = async { let req = HttpWebRequest.Create(url) // Run operation asynchronously let! resp = req.AsyncGetResponse() let stream = resp.GetResponseStream() // Dispose 'StreamReader' when completed use reader = new StreamReader(stream) // Run asynchronously and then return the result return! reader.AsyncReadToEnd() } In F# expert book (and many other sources), they say like let! var = expr simply means "perform the asynchronous operation expr and bind the result to var when the operation completes. Then continue by executing the rest of the computation body" I also know that a new thread is created when performing async operation. My original understanding was that there are two parallel threads after the async operation, one doing I/O and one continuing to execute the async body at the same time. But in this example, I am confused at let! resp = req.AsyncGetResponse() let stream = resp.GetResponseStream() What happens if resp has not started yet and the thread in the async body wants to GetResponseStream? Is this a possible error? So maybe my original understanding was wrong. The quoted sentences in the F# expert book actually means that "creating a new thread, hang the current thread up, when the new thread finishes, wake up the body thread and continue", but in this case I don't see we could save any time. In the original understanding, the time is saved when there are several independent IO operations in one async block so that they could be done at the same time without intervention with each other. But here, if I don't get the response, I cannot create the stream; only I have stream, I can start reading the stream. Where's the time gained?

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• NSDate out of scope

  - by therealtkd

  Having problems with out of scope for NSDate in an iphone app. I have an interface defined like this: @interface MyObject : NSoObject { NSMutableArray *array; BOOL checkThis; NSDate *nextDue; } Now in the implementation I have this: -(id) init { if( (self=[super init]) ) { checkThis = NO; array = [[NSMutableArray alloc] init]; nextDue = [[NSDate date] retain]; NSDate *testDate = [NSDate date]; } return self; } Now, if I trace through the init, before I actually assign the variables checkThis shows as boolean. array shows as pointer 0x0 because it hasn't ben assigned. But the nextDue is showing as 'out of scope'. I don't understand why this is out of scope but the other variables aren't. If I trace through the code until after the variables are assigned, array now shows as being correctly assigned but nextDue is still out of scope. Interestingly, the testDate variable is assigned just fine and the debugger shows this as a valid date. Further interesting point is if I move the mouse over the testDate variable while I am debugging, it shows as an 'NSDate *' type which I would expect since that's its definition. Yet the nextDue, which to me is defined the same way is showing as a '_NSCFDate *'. Any googling I did on the subject said that the retain is the problem, but its actually out of scope before I even try to assign the variable. However, in another class, the same definition for NSDate work ok. It shows as nil before a value is assigned to it. Arghhh

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