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• What's a good Java-based Master-Slave communication mechanism?

  - by plecong

  I'm creating a Java application that requires master-slave communication between JVMs, possibly residing on the same physical machine. There will be a "master" server running inside a JEE application server (i.e. JBoss) that will have "slave" clients connect to it and dynamically register itself for communication (that is the master will not know the IP addresses/ports of the slaves so cannot be configured in advance). The master server acts as a controller that will dole work out to the slaves and the slaves will periodically respond with notifications, so there would be bi-directional communication. I was originally thinking of RPC-based systems where each side would be a server, but it could get complicated, so I'd prefer a mechanism where there's an open socket and they talk back and forth. I'm looking for a communication mechanism that would be low-latency where the messages would be mostly primitive types, so no serious serialization is necessary. Here's what I've looked at: RMI JMS: Built-in to Java, the "slave" clients would connect to the existing ConnectionFactory in the application server. JAX-WS/RS: Both master and slave would be servers exposing an RPC interface for bi-directional communication. JGroups/Hazelcast: Use shared distributed data structures to facilitate communication. Memcached/MongoDB: Use these as "queues" to facilitate communication, though the clients would have to poll so there would be some latency. Thrift: This does seem to keep a persistent connection, but not sure how to integrate/embed a Thrift server into JBoss WebSocket/Raw Socket: This would work, but require a lot more custom code than I'd like. Is there any technology I'm missing? Edit: Also looked at: JMX: Have the client connect to JBoss' JMX server and receive JMX notifications for bidirectional comms.

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• How does a client find the port number of a server?

  - by Jonathan

  Hello all, I am currently learning about basic networking in java. I have been playing around with the server and client relationship between two of my computers. However, I cannot figure out how distributed programs (say, a videogame), can not only find the 'host' computer, but also the port number on which the server is running in order to create a Socket between the two computers. The only way I really see to create a Socket is with an already known IP Address, and with a known port number. How do you search a LAN network for another computer (host) searching for clients? How do you determine what port the server is located on without 'pinging' all available ports for a response (which, I understand, is bad form... Something about 'server attack'...)? In such a situation as a video game, there can be any number of computers on the same network, and any number of them might be attempting to host, or otherwise running the application. Any other important information, or perhaps reference to a more detailed tutorial than the one I am using, regarding making connections on so very little information on the client side would be appreciated. Many thanks, Jonathan

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• Java Process.waitFor() and IO streams

  - by lynks

  I have the following code; String[] cmd = { "bash", "-c", "~/path/to/script.sh" }; Process p = Runtime.getRuntime().exec(cmd); PipeThread a = new PipeThread(p.getInputStream(), System.out); PipeThread b = new PipeThread(p.getErrorStream(), System.err); p.waitFor(); a.die(); b.die(); The PipeThread class is quite simple so I will include it in full; public class PipeThread implements Runnable { private BufferedInputStream in; private BufferedOutputStream out; public Thread thread; private boolean die = false; public PipeThread(InputStream i, OutputStream o) { in = new BufferedInputStream(i); out = new BufferedOutputStream(o); thread = new Thread(this); thread.start(); } public void die() { die = true; } public void run() { try { byte[] b = new byte[1024]; while(!die) { int x = in.read(b, 0, 1024); if(x > 0) out.write(b, 0, x); else die(); out.flush(); } } catch(Exception e) { e.printStackTrace(); } try { in.close(); out.close(); } catch(Exception e) { } } } My problem is this; p.waitFor() blocks endlessly, even after the subprocess has terminated. If I do not create the pair of PipeThread instances, then p.waitFor() works perfectly. What is it about the piping of io streams that is causing p.waitFor() to continue blocking? I'm confused as I thought the IO streams would be passive, unable to keep a process alive, or to make Java think the process is still alive.

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• How to write a Criteria Query when there's an <any> association

  - by Bevan

  I'm having some trouble constructing the correct Criteria to do a particular query - after an afternoon of consultation with Professor Google, I'm hoping that someone can point me in the right direction. I have two entities of interest: OutputTsDef and NamedAttribute What I'm trying to do is to find all OutputTsDef that have a particular NamedAttribute value. I can write a detached Criteria to find all NamedAttributes that have a given name and value: var attributesCriteria = DetachedCriteria.For<INamedAttribute>() .Add(Expression.Eq("Name", "some name")) .Add(Expression.Eq("Value", "some value")); How do I inject this in to a query for OutputTsDef to restrict the results? var criteria = nHibernateSession.CreateCriteria(typeof(IOutputTsDefEntity)); // What do I write here? var results = criteria.List(); NamedAttribute looks like this - note the use of [Any] as we can have NamedAttributes on many kinds of entity. [AttributeIdentifier("DbKey", Name = "Id.Column", Value = "NamedAttributeID")] [Class(Table = "NamedAttributes")] public class NamedAttribute : BusinessEntity, INamedAttribute { [Any(0, Name = "Entity", MetaType = "System.String", IdType = "System.Int32")] [MetaValue(1, Class = "Sample.OutputTsDef, Sample.Entities", Value = "OTD")] [MetaValue(2, Class = "Sample.OutputTimeSeriesAttributesEntity, Sample.Entities", Value = "OTA")] [Column(3, Name = "OwnerType")] [Column(4, Name = "OwnerKey")] public virtual IBusinessEntity Entity { get; set; } [Property(Column = "Name")] public virtual string Name { get; set; } [Property(Column = "Value")] public virtual string Value { get; set; } ... omitted ... } In regular SQL, I'd just include an extra "where" clause like this: where OutputTsDefId in ( select distinct OwnerKey from NamedAttributes where Name = ? and Value = ? and OwnerType = 'OTD' ) What am I missing? (Question also posted to the NHUsers mailing list - I'll copy any useful information from there, here.)

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• Does SetFileBandwidthReservation affect memory-mapped file performance?

  - by Ghostrider

  Does this function affect Memory-mapped file performance? Here's the problem I need to solve: I have two applications competing for disk access: "reader" and "updater". Whole system runs on Windows Server 2008 R2 x64 "Updater" constantly accesses disk in a linear manner, updating data. They system is set up in such a way that updater always has infinite data to update. Consider that it is constantly approximating a solution of a huge set of equations that takes up entire 2TB disk drive. Updater uses ReadFile and WriteFile to process data in a linear fashion. "Reader" is occasionally invoked by user to get some pieces of data. Usually user would read several 4kb blocks from the drive and stop. Occasionally user needs to read up to 100mb sequentially. In exceptional cases up to several gigabytes. Reader maps files to memory to get data it needs. What I would like to achieve is for "reader" to have absolute priority so that "updater" would completely stop if needed so that "reader" could get the data user needs ASAP. Is this problem solvable by using SetPriorityClass and SetFileBandwidthReservation calls? I would really hate to put synchronization login in "reader" and "updater" and rather have the OS take care of priorities.

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• How do I return an array from a method?

  - by dwwilson66

  I'm trying to create a deck of cards for my homework. Code is posted below. I need to create four sets of cards (the four suits) and am create a multidimensional array. When I print the results instead of trying to pass the array, I can see that the data in the array is as expected. However, when I try to pass the array card, I get an error cannot find symbol. I've got this modeled after texbook and Java tutorial examples, and I need some help figuring out what I'm missing. I've over-documented to give an idea of how I'm thinking this SHOULD work...please let me know where I've gone horribly wrong in my understanding. import java.util.*; import java.lang.*; // public class CardGame { public static int[][] main(String[] args) { int[][] startDeck = deckOfCards(); /* cast new deck as int[][], calling method deckOfCards System.out.println(" /// from array: " + Arrays.deepToString(startDeck)); } public static int[][] deckOfCards() /* method to return a multi-dimensional array */ { int rank; int suit; for(rank=1;rank<14;rank++) /* cards 1 - 13 .... */ { for(suit=1;suit<5;suit++) /* suits 1 - 4 .... */ { int[][] card = new int[][] /* define a new card... */ { {rank,suit} /* with rank/suit from for... loops */ }; System.out.println(" /// from array: " + Arrays.deepToString(card)); } } return card; /* Error: cannot find symbol } }

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• Ant fails without message at javac

  - by digitala

  I've written an Ant build.xml file which obtains a number of source files via WSDL and compiles them. These have been working on an old, now destroyed (and therefore unavailable for comparison), system but the build process isn't completing on this newer, faster system. The relevant section of the build file looks like this: <target name="compile" depends="init"> <java classname="org.apache.axis.wsdl.WSDL2Java"> <arg line="--all --server-side --skeletonDeploy --factory --wrapArrays --output src ${srcurl}" /> </java> <javac srcdir="${src}" destdir="${build}" verbose="yes" /> </target> The files are downloaded via the WSDL service successfully, however after that point Ant simply stops & returns to the commandline. Versions of the relevant apps: # java -version java version "1.6.0_14" Java(TM) SE Runtime Environment (build 1.6.0_14-b08) Java HotSpot(TM) 64-Bit Server VM (build 14.0-b16, mixed mode) # javac -version javac 1.6.0_14 # ant -version Apache Ant version 1.6.5 compiled on January 6 2007 I'm assuming that there's a problem with javac that Ant isn't passing back. Is there any way I can get some debugging information from javac? I've tried adding a <record /> tag to the target but that doesn't give any more information than running ant -v does. Any other suggestions would be great, also!

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• Problem in filtering records using Dataview (C#3.0)

  - by Newbie

  I have a data table . The data table is basically getting populated from excel sheet. And there are many excel sheets. Henceforth, I have written a utility method for accomplishing the same. Now in some of the excel sheets, there are date columns and in some it is not(only text/string). My function is populating the values properly into the datatable from the excell sheet. But there are many blank rows in the excel sheets some are filled with NULL , some with " ". So I need to filter those records (which are NULL or " " ) first before further processing. What I am after is to use a dataview and apply the filter over there. DataView dv = dataTable.DefaultView; dv.RowFilter = ColumnName + " <> ''"; Well by using metedata (GetOleDbSchemaTable(OleDbSchemaGuid.Columns, restrection)) I was able to get the column names from the excel sheet , so getting the column names is not an issue. But the problem is as I said in some Excel sheet there are date fileds some are not. So the Filter condition of the Dataview needs to be proper. If I apply the above logic, and if it encounters a Datafield, it is throwing error Cannot perform '<' operation on System.DateTime and System.String. Could you people please help me out? I need to filter columns(not known at compile time + their data types) which can have NULL and " " I am using C#3.0 Thanks

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• Using boost asio for pub/sub style tcp in a game loop

  - by unohoo

  I have been reading through the boost asio documentation for a couple of hours now, and while I think the documentation is really great, I am still left a bit confused on how to implement the system that I need. I have to stream info, from a game engine, to a list of computers over tcp. One snag is that, unlike traditional pub/sub, the computer that does the distribution of info is actually the computer that has to connect to the subscribers as well (instead of the subscribers registering with the publisher). This is done via a config file - a list of ip's/ports along with the data that they each require. The subscribers listen, but do not know the ip of the publisher. (As a side note, I'm quite new to network programming, so maybe I'm missing something .. but it's strange that I do not find much information regarding this style of "inverted" client-server model..) I am looking for suggestions for the implementation of such a system using boost asio. Of course I have to integrate the networking into an already existing engine, so with regards to that: What would be a good way to handle messages being sent to multiple computers every frame? Use async_write, call io_service.run and then reset every frame? Would having io_service.run have its own thread be better? Or should I just use threads and use blocking writes?

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• Null Pointer Exception in Primavera P6 8.1

  - by gwrichard

  I am getting a null pointer exception in a Primavera P6 8.1 installation. The exception only occurs in one section of the web-client: Application settings.P6 web and the P6 API are deployed on the same WebLogic (10.3.5) node running on a Windows Server 2008 R2 installation. I have done this installation using this same software stack a dozen times and don't have this issue on any of the other installs. Exact error below: Match: beginTraversal Match: digest selected JREDesc: JREDesc[version 1.6.0_20+, heap=-1--1, args=null, href=http://java.sun.com/products/autodl/j2se, sel=false, null, null], JREInfo: JREInfo for index 0: platform is: 1.7 product is: 1.7.0_17 location is: http://java.sun.com/products/autodl/j2se path is: C:\Program Files (x86)\Java\jre7\bin\javaw.exe args is: null native platform is: Windows, x86 [ x86, 32bit ] JavaFX runtime is: JavaFX 2.2.7 found at C:\Program Files (x86)\Java\jre7\ enabled is: true registered is: true system is: true Match: ignoring maxHeap: -1 Match: ignoring InitHeap: -1 Match: digesting vmargs: null Match: digested vmargs: [JVMParameters: isSecure: true, args: ] Match: JVM args after accumulation: [JVMParameters: isSecure: true, args: ] Match: digest LaunchDesc: http://localhost:7001/p6/action/jnlp/appletsjnlp.jnlp?mainClass=com.primavera.pvapplets.adminpreferences.AdminPreferencesApplet&classPath=adminpreferences.jar,prm-applets-common.jar,forms-1.0.7.jar,prm-guisupport.jar,prm-to.jar,jide.jar,tablesupport.jar,formsupport.jar,applets-bo.jar,commons-lang.jar,prm-common.jar,resource_strings.jar,prm-img.jar,commons-logging.jar&name=AdminPreferences&version=8.1.2.0.0602 Match: digest properties: [] Match: JVM args: [JVMParameters: isSecure: true, args: ] Match: endTraversal .. Match: JVM args final: Match: Running JREInfo Version match: 1.7.0.17 == 1.7.0.17 Match: Running JVM args match: have:<> satisfy want:<> Java Plug-in 10.17.2.02 Using JRE version 1.7.0_17-b02 Java HotSpot(TM) Client VM User home directory = C:\Users\gwrichard ---------------------------------------------------- c: clear console window f: finalize objects on finalization queue g: garbage collect h: display this help message l: dump classloader list m: print memory usage o: trigger logging q: hide console r: reload policy configuration s: dump system and deployment properties t: dump thread list v: dump thread stack x: clear classloader cache 0-5: set trace level to <n> ----------------------------------------------------

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• Which software for intranet CMS - Django or Joomla?

  - by zalun

  In my company we are thinking of moving from wiki style intranet to a more bespoke CMS solution. Natural choice would be Joomla, but we have a specific architecture. There is a few hundred people who will use the system. System should be self explainable (easier than wiki). We use a lot of tools web, applications and integrated within 3rd party software. The superior element which is a glue for all of them is API. In example for the intranet tools we do use Django, but it's used without ORM, kind of limited to templates and url - every application has an adequate methods within our API. We do not use the Django admin interface, because it is hardly dependent on ORM. Because of that Joomla may be hard to integrate. Every employee should be able to edit most of the pages, authentication and privileges have to be managed by our API. How hard is it to plug Joomla to use a different authentication process? (extension only - no hacks) If one knows Django better than Joomla, should Django be used?

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• Cannot write to SD card -- canWrite is returning false

  - by Fizz

  Sorry for the ambiguous title but I'm doing the following to write a simple string to a file: try { File root = Environment.getExternalStorageDirectory(); if (root.canWrite()){ System.out.println("Can write."); File def_file = new File(root, "default.txt"); FileWriter fw = new FileWriter(def_file); BufferedWriter out = new BufferedWriter(fw); String defbuf = "default"; out.write(defbuf); out.flush(); out.close(); } else System.out.println("Can't write."); }catch (IOException e) { e.printStackTrace(); } But root.canWrite() seems to be returning false everytime. I am not running this off of an emulator, I have my android Eris plugged into my computer via USB and running the app off of my phone via Eclipse. Is there a way of giving my app permission so this doesn't happen? Also, this code seems to be create the file default.txt but what if it already exists, will it ignore the creation and just open it to write or do I have to catch something like FileAlreadyExists(if such an exception exists) which then just opens it and writes? Thanks for any help guys.

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• Problem with LINQ in C#

  - by David Bonnici

  I am encountering a problem when using LINQ in C#, I am constantly getting "Specified cast is not valid". This is what I am trying to do. I create a class in which I declare all the columns of the table. [Table(Name="tbl_Aff")] public class Affiliate { [Column] public string name; [Column] public string firstname; [Column] public string surname; [Column] public string title; } I then declare a strongly typed DataContext in which I declare all Table collections as members of the context. public partial class Database : DataContext { public Table affiliate; public Database() : base(Settings.getConnectionString()) { } //This method gets the connection string by reading from an XML file. } public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Database database = new Database(); try { var q = from a in database.affiliate select a; foreach (var aff in q) // Here I get the error "Specified cast is not valid" { lblMessage.InnerHtml += aff.name + ""; } } catch (Exception ex) { System.Console.WriteLine(ex.Message); } } }

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• Help with Hashmaps in Java

  - by Crystal

  I'm not sure how I use get() to get my information. Looking at my book, they pass the key to get(). I thought that get() returns the object associated with that key looking at the documentation. But I must be doing something wrong here.... Any thoughts? import java.util.*; public class OrganizeThis { /** Add a person to the organizer @param p A person object */ public void add(Person p) { staff.put(p, p.getEmail()); System.out.println("Person " + p + "added"); } /** * Find the person stored in the organizer with the email address. * Note, each person will have a unique email address. * * @param email The person email address you are looking for. * */ public Person findByEmail(String email) { Person aPerson = staff.get(email); return aPerson; } private Map<Person, String> staff = new HashMap<Person, String>(); public static void main(String[] args) { OrganizeThis testObj = new OrganizeThis(); Person person1 = new Person("J", "W", "111-222-3333", "[email protected]"); testObj.add(person1); System.out.println(testObj.findByEmail("[email protected]")); } }

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• Unable to set up ODBC after installing ODAC (Xcopy)

  - by rwilson513

  We are trying to use ODAC Xcopy to minimize the footprint of installing Oracle 11g Client. Currently, we use the Oracle 11g Admin install (~700mb). I've tried using the ODAC Xcopy, and that works. However, the only issue I now have is that I cannot set up an ODBC on the target system by just installing the ODAC Xcopy. After installing ODAC (Windows XP fyi), I go to Control Panel--Admin Tools--Data Sources (ODBC)--System DSN--Add--Microsoft ODBC for Oracle. I get the following error: "The Oracle(tm) client and networking components were not found. These components are supplied by Oracle and are part of the Oracle Version 7.3 (or greater) client software installation. You will be unable to use this driver until these components have been installed." I've tried editing the registry and creating the same keys that the Oracle Admin install creates, but still no luck. I'm not sure how to get past this. Any suggestions? Thanks in advance.

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• How should I use .ico files in a Winforms Application ?

  - by Brann

  I'm developing a WinForms c# 3.0 application. Our designer created quite a lot of .ico files containing all the needed art. The choice of .ico was made because quite often, the same image is needed in several places in different dimensions. Now, it seems .ico files are really annoying to use in visual studio. The only way to use those images seems to be through images list (which aren't supported by all controls). Compared to other resources, you can't write this : foo.Image = global::RFQHUB.RFQHUBClient.Properties.Resources.foo; // Cannot implicitly convert type 'System.Drawing.Icon' to 'System.Drawing.Image' Here are the options I'm considering : create ImageLists of all possible sizes referencing all my icons in my main window. Link these ImageLists from other windows and find a way to export Image objects from the ImageList when I can't use it directly ; since ImageList contains a Draw() method, this should probably be possible. convert all the x.ico I've got in several x16.gif ...x48.gif, and use those through resources. I'd be interested to know if some people have been successfully using .ico resources in a Winform application. In so, how did you set up things ?

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• Access 2007 DAO VBA Error 3381 causes objects in calling methods to "break".

  - by MT

  ---AFTER FURTHER INVESTIGATION--- "tblABC" in the below example must be a linked table (to another Access database). If "tblABC" is in the same database as the code then the problem does not occur. Hi, We have recently upgraded to Office 2007. We have a method in which we have an open recordset (DAO). We then call another sub (UpdatingSub below) that executes SQL. This method has its own error handler. If error 3381 is encountered then the recordset in the calling method becomes "unset" and we get error 3420 'Object invalid or no longer set'. Other errors in UpdatingSub do not cause the same problem. This code works fine in Access 2003. Private Sub Whatonearth() Dim rs As dao.Recordset set rs = CurrentDb.OpenRecordset("tblLinkedABC") Debug.Print rs.RecordCount UpdatingSub "ALTER TABLE tblTest DROP Column ColumnNotThere" 'Error 3240 occurs on the below line even though err 3381 is trapped in the calling procedure 'This appears to be because error 3381 is encountered when calling UpdatingSub above Debug.Print rs.RecordCount End Sub Private Sub WhatonearthThatWorks() Dim rs As dao.Recordset set rs = CurrentDb.OpenRecordset("tblLinkedABC") Debug.Print rs.RecordCount 'Change the update to generate a different error UpdatingSub "NONSENSE SQL STATEMENT" 'Error is trapped in UpdatingSub. Next line works fine. Debug.Print rs.RecordCount End Sub Private Sub UpdatingSub(strSQL As String) On Error GoTo ErrHandler: CurrentDb.Execute strSQL ErrHandler: 'LogError' End Sub Any thoughts? We are running Office Access 2007 (12.0.6211.1000) SP1 MSO (12.0.6425.1000). Perhaps see if SP2 can be distributed? Sorry about formatting - not sure how to fix that.

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• Native functions throw UnsatisfiedLinkError in custom view, despite working in main activity

  - by Mark Ingram

  For some reason I can only call native functions from my main activity and not any custom views that I've created. Here is an example file (I followed a tutorial, but renamed the classes http://mindtherobot.com/blog/452/android-beginners-ndk-setup-step-by-step/) See the usage of the native function "getNewString". package com.example.native; import android.app.Activity; import android.app.AlertDialog; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.os.Bundle; import android.view.View; public class NativeTestActivity extends Activity { static { System.loadLibrary("nativeTest"); } private native String getNewString(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(new BitmapView(this)); String hello = getNewString(); // This line works fine new AlertDialog.Builder(this).setMessage(hello).show(); } } class BitmapView extends View { static { System.loadLibrary("nativeTest"); } private native String getNewString(); public BitmapView(Context context) { super(context); String hello = getNewString(); // This line throws the UnsatisfiedLinkError new AlertDialog.Builder(this.getContext()).setMessage(hello).show(); } } How can I call native functions in my custom views? I've built the application as an Android 2.2 app. I'm running the application on my HTC Desire. I have the latest SDK (9) and latest NDK (r5).

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• implementing gravity to projectile - delta time issue

  - by Murat Nafiz

  I'm trying to implement a simple projectile motion in Android (with openGL). And I want to add gravity to my world to simulate a ball's dropping realistically. I simply update my renderer with a delta time which is calculated by: float deltaTime = (System.nanoTime()-startTime) / 1000000000.0f; startTime = System.nanoTime(); screen.update(deltaTime); In my screen.update(deltaTime) method: if (isballMoving) { golfBall.updateLocationAndVelocity(deltaTime); } And in golfBall.updateLocationAndVelocity(deltaTime) method: public final static double G = -9.81; double vz0 = getVZ0(); // Gets initial velocity(z) double z0 = getZ0(); // Gets initial height double time = getS(); // gets total time from act begin double vz = vz0 + G * deltaTime; // calculate new velocity(z) double z = z0 - vz0 * deltaTime- 0.5 * G * deltaTime* deltaTime; // calculate new position time = time + deltaTime; // Update time setS(time); //set new total time Now here is the problem; If I set deltaTime as 0.07 statically, then the animation runs normally. But since the update() method runs as faster as it can, the length and therefore the speed of the ball varies from device to device. If I don't touch deltaTime and run the program (deltaTime's are between 0.01 - 0.02 with my test devices) animation length and the speed of ball are same at different devices. But the animation is so SLOW! What am I doing wrong?

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• No Buffer Space available(maximum connection reached?) Form Postgres EDB Driver

  - by Listening.Platform

  We are facing an exception while connecting to database through our java application. The stack trace is as follows com.edb.util.PSQLException: The connection attempt failed. at com.edb.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:189) at com.edb.core.ConnectionFactory.openConnection(ConnectionFactory.java:64) at com.edb.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:161) at com.edb.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:30) at com.edb.jdbc3.Jdbc3Connection.<init>(Jdbc3Connection.java:24) at com.edb.Driver.makeConnection(Driver.java:391) at com.edb.Driver.connect(Driver.java:266) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) ... 12 more Caused by: java.net.SocketException: No buffer space available (maximum connections reached?): connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(Unknown Source) at java.net.PlainSocketImpl.connectToAddress(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.<init>(Unknown Source) at java.net.Socket.<init>(Unknown Source) at com.edb.core.PGStream.<init>(PGStream.java:70) at com.edb.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:115) ... 20 more When the error occured we were not able to connect to internet and DB and had to reboot the system. But the error occured again after 3 days at same code i.e while connecting to DB. We checked TCP connections using netstat. But there were not many TCP connections i.e it has not reached the max limit. Our application has multiple long running Java processes that pools the DB connections (not more than 60) and keeps it alive for firing the next query (as it has to poll the DB every 2 seconds). Some of the queries in our application are joining large tables (10 million records) to get the related data. We are using following System and applications Windows 2003 server SP2 Java 1.6 Postgres Plus Advanced server 8.4 Database edb-jdbc14.jar driver for connection DB from Java We have used the default configuration of Postgres DB except increasing the connection to 120 from 100. Has anybody encountred the same error with postgres edb driver? Can anybody help us finding the solution?

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• Testing ASP.NET webservice using NUnit and transferring session state

  - by herbertyeung

  I have a NUnit test class that starts an ASP.NET web service (using Microsoft.VisualStudio.WebHost.Server) which runs on http://localhost:1070 The problem I am having is that I want to create a session state within the NUnit test that is accessible by the ASP.NET web service on localhost:1070. I have done the following, and the session state can be created successfully inside the NUnit Test, but is lost when the web service is invoked: //Create a new HttpContext for NUnit Testing based on: //http://blogs.imeta.co.uk/jallderidge/archive/2008/10/19/456.aspx HttpContext.Current = new HttpContext( new HttpRequest("", "http://localhost:1070/", ""), new HttpResponse( new System.IO.StringWriter())); //Create a new HttpContext.Current for NUnit Testing System.Web.SessionState.SessionStateUtility.AddHttpSessionStateToContext( HttpContext.Current, new HttpSessionStateContainer("", new SessionStateItemCollection(), new HttpStaticObjectsCollection(), 20000, true, HttpCookieMode.UseCookies, SessionStateMode.Off, false)); HttpContext.Current.Session["UserName"] = "testUserName"; testwebService.testMethod(); I want to be able to get the session state created in the NUnit test for Session["UserName"] in the ASP.NET web service: [WebMethod(EnableSession=true)] public int testMethod() { string user; if(Session["UserName"] != null) { user = (string)Session["UserName"]; //Do some processing of the user return 1; } else return 0; } The web.config file has the following configuration for the session state configuration and would like to remain using InProc than rather StateServer Or SQLServer: <sessionState mode="InProc" stateConnectionString="tcpip=127.0.0.1:42424" cookieless="false" timeout="20"/>

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• Using Reflection.Emit to emit a "using (x) { ... }" block?

  - by Lasse V. Karlsen

  I'm trying to use Reflection.Emit in C# to emit a using (x) { ... } block. At the point I am in code, I need to take the current top of the stack, which is an object that implements IDisposable, store this away in a local variable, implement a using block on that variable, and then inside it add some more code (I can deal with that last part.) Here's a sample C# piece of code I tried to compile and look at in Reflector: public void Test() { TestDisposable disposable = new TestDisposable(); using (disposable) { throw new Exception("Test"); } } This looks like this in Reflector: .method public hidebysig instance void Test() cil managed { .maxstack 2 .locals init ( [0] class LVK.Reflection.Tests.UsingConstructTests/TestDisposable disposable, [1] class LVK.Reflection.Tests.UsingConstructTests/TestDisposable CS$3$0000, [2] bool CS$4$0001) L_0000: nop L_0001: newobj instance void LVK.Reflection.Tests.UsingConstructTests/TestDisposable::.ctor() L_0006: stloc.0 L_0007: ldloc.0 L_0008: stloc.1 L_0009: nop L_000a: ldstr "Test" L_000f: newobj instance void [mscorlib]System.Exception::.ctor(string) L_0014: throw L_0015: ldloc.1 L_0016: ldnull L_0017: ceq L_0019: stloc.2 L_001a: ldloc.2 L_001b: brtrue.s L_0024 L_001d: ldloc.1 L_001e: callvirt instance void [mscorlib]System.IDisposable::Dispose() L_0023: nop L_0024: endfinally .try L_0009 to L_0015 finally handler L_0015 to L_0025 } I have no idea how to deal with that ".try ..." part at the end there when using Reflection.Emit. Can someone point me in the right direction?

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• How to benchmark on multi-core processors

  - by Pascal Cuoq

  I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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• volatile keyword seems to be useless?

  - by Finbarr

  import java.util.concurrent.CountDownLatch; import java.util.concurrent.atomic.AtomicInteger; public class Main implements Runnable { private final CountDownLatch cdl1 = new CountDownLatch(NUM_THREADS); private volatile int bar = 0; private AtomicInteger count = new AtomicInteger(0); private static final int NUM_THREADS = 25; public static void main(String[] args) { Main main = new Main(); for(int i = 0; i < NUM_THREADS; i++) new Thread(main).start(); } public void run() { int i = count.incrementAndGet(); cdl1.countDown(); try { cdl1.await(); } catch (InterruptedException e1) { e1.printStackTrace(); } bar = i; if(bar != i) System.out.println("Bar not equal to i"); else System.out.println("Bar equal to i"); } } Each Thread enters the run method and acquires a unique, thread confined, int variable i by getting a value from the AtomicInteger called count. Each Thread then awaits the CountDownLatch called cdl1 (when the last Thread reaches the latch, all Threads are released). When the latch is released each thread attempts to assign their confined i value to the shared, volatile, int called bar. I would expect every Thread except one to print out "Bar not equal to i", but every Thread prints "Bar equal to i". Eh, wtf does volatile actually do if not this?

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• How to query AD to get name email from lan id

  - by Kumar

  I have some code in asp.net ( kindly given by someone else ) to query AD to get user name and email etc. using System.DirectoryServices; using System.DirectoryServices.ActiveDirectory; using ActiveDs; DirectorySearcher search = new DirectorySearcher(new DirectoryEntry(), string.Format("(samaccountname={0})", id)); if (search == null) return id; if (search.FindOne() == null) return id; DirectoryEntry usr = search.FindOne().GetDirectoryEntry(); IADsUser oUsr = (IADsUser)usr.NativeObject; return string.Format("{0} {1}", usr.Properties["givenname"].Value, usr.Properties["sn"].Value); However this requires impersonation with an id that's required to be changed every 2 weeks and then updated in the web.config which is often forgotten Is there any non impersonation code to achieve the same result ? UPDATE - it's a config tool and it looks up name, email id etc. I like the service a/c idea Q - How is it possible to run ( impersonate ) just the AD code with a "service" a/c ? any samples/code ? how do you impersona

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