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• Need Advice on Server configuration

  - by user45324

  I have lab of 80 computer in my school. I need to run terminal server on each pc using remote desktop service of Microsoft server 2003. I need to run applications like Java, .NET, wamp, turbo c and other low memory applications like ms office and internet. so, could you please recommended some configuration for Mother Board and Processor. If you need any other information feel free to ask.

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• Android image click in horizontal page view

  - by JaseemAmeer

  I've implemented horizontal page view with many images. And I'm trying to create a click event on the image. public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.pbase); ImageView binfo,bheacno; tvHeacno=(TextView) findViewById(R.id.tvheacno); heacno=getHeacno(); tvHeacno.setText(heacno); MyPagerAdapter adapter=new MyPagerAdapter(); ViewPager myPager=(ViewPager)findViewById(R.id.mythreepanelpager); myPager.setAdapter(adapter); myPager.setCurrentItem(0); binfo=(ImageView) findViewById(R.id.ivinfo); bheacno=(ImageView) findViewById(R.id.ivheacno); binfo.setOnClickListener(this); bheacno.setOnClickListener(this); } then i've MyPagerAdapter class and the onclik method. it returns null to binfo and hence fails at binfo.setOnClickListener(this) I've done image click before on normal pages successfully. Is it because of horizontal page views? How can I solve this issue?? <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_weight="33" android:layout_gravity="top" android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_weight="33" android:layout_gravity="center_horizontal" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivinfo" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/information" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text=" Information " /> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="center_horizontal" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivheacno" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/heacno" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="Get HEAC Number" /> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="center_horizontal" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivpi" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/pi" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="Personal Information" /> </LinearLayout> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="center" android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_weight="33" android:layout_gravity="left" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivassn" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/assn" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="Add Social Security Number" /> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="left" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivvssn" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/vssn" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="View Social Security Number" /> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="left" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivdssn" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/dssn" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="Delete Social Security Number" /> </LinearLayout> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="bottom" android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_weight="33" android:layout_gravity="left" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivali" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/ali" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="Add Low Income" /> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="left" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivvli" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/vli" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="View Low Income" /> </LinearLayout> <LinearLayout android:layout_weight="33" android:layout_gravity="left" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:gravity="center" android:layout_weight="50" android:id="@+id/ivdli" android:layout_width="wrap_content" android:layout_gravity="center" android:layout_height="wrap_content" android:src="@drawable/dli" /> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textColor="@android:color/black" android:layout_weight="50" android:layout_gravity="center" android:gravity="center" android:text="Delete Low Income" /> </LinearLayout> </LinearLayout> </LinearLayout>

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• Adding Polynomials (Linked Lists)......Bug Help

  - by Brian

  I have written a program that creates nodes that in this class are parts of polynomials and then the two polynomials get added together to become one polynomial (list of nodes). All my code compiles so the only problem I am having is that the nodes are not inserting into the polynomial via the insert method I have in polynomial.java and when running the program it does create nodes and displays them in the 2x^2 format but when it comes to add the polynomials together it displays o as the polynomials, so if anyone can figure out whats wrong and what I can do to fix it it would be much appreciated. Here is the code: import java.util.Scanner; class Polynomial{ public termNode head; public Polynomial() { head = null; } public boolean isEmpty() { return (head == null); } public void display() { if (head == null) System.out.print("0"); else for(termNode cur = head; cur != null; cur = cur.getNext()) { System.out.println(cur); } } public void insert(termNode newNode) { termNode prev = null; termNode cur = head; while (cur!=null && (newNode.compareTo(cur)<0)) { prev = null; cur = cur.getNext(); } if (prev == null) { newNode.setNext(head); head = newNode; } else { newNode.setNext(cur); prev.setNext(newNode); } } public void readPolynomial(Scanner kb) { boolean done = false; double coefficient; int exponent; termNode term; head = null; //UNLINK ANY PREVIOUS POLYNOMIAL System.out.println("Enter 0 and 0 to end."); System.out.print("coefficient: "); coefficient = kb.nextDouble(); System.out.println(coefficient); System.out.print("exponent: "); exponent = kb.nextInt(); System.out.println(exponent); done = (coefficient == 0 && exponent == 0); while(!done) { Polynomial poly = new Polynomial(); term = new termNode(coefficient,exponent); System.out.println(term); poly.insert(term); System.out.println("Enter 0 and 0 to end."); System.out.print("coefficient: "); coefficient = kb.nextDouble(); System.out.println(coefficient); System.out.print("exponent: "); exponent = kb.nextInt(); System.out.println(exponent); done = (coefficient==0 && exponent==0); } } public static Polynomial add(Polynomial p, Polynomial q) { Polynomial r = new Polynomial(); double coefficient; int exponent; termNode first = p.head; termNode second = q.head; termNode sum = r.head; termNode term; while (first != null && second != null) { if (first.getExp() == second.getExp()) { if (first.getCoeff() != 0 && second.getCoeff() != 0); { double addCoeff = first.getCoeff() + second.getCoeff(); term = new termNode(addCoeff,first.getExp()); sum.setNext(term); first.getNext(); second.getNext(); } } else if (first.getExp() < second.getExp()) { sum.setNext(second); term = new termNode(second.getCoeff(),second.getExp()); sum.setNext(term); second.getNext(); } else { sum.setNext(first); term = new termNode(first.getNext()); sum.setNext(term); first.getNext(); } } while (first != null) { sum.setNext(first); } while (second != null) { sum.setNext(second); } return r; } } Here is my Node class: class termNode implements Comparable { private int exp; private double coeff; private termNode next; public termNode(double coefficient, int exponent) { coeff = coefficient; exp = exponent; next = null; } public termNode(termNode inTermNode) { coeff = inTermNode.coeff; exp = inTermNode.exp; } public void setData(double coefficient, int exponent) { coefficient = coeff; exponent = exp; } public double getCoeff() { return coeff; } public int getExp() { return exp; } public void setNext(termNode link) { next = link; } public termNode getNext() { return next; } public String toString() { if (exp == 0) { return(coeff + " "); } else if (exp == 1) { return(coeff + "x"); } else { return(coeff + "x^" + exp); } } public int compareTo(Object other) { if(exp ==((termNode) other).exp) return 0; else if(exp < ((termNode) other).exp) return -1; else return 1; } } And here is my Test class to run the program. import java.util.Scanner; class PolyTest{ public static void main(String [] args) { Scanner kb = new Scanner(System.in); Polynomial r; Polynomial p = new Polynomial(); System.out.println("Enter first polynomial."); p.readPolynomial(kb); Polynomial q = new Polynomial(); System.out.println(); System.out.println("Enter second polynomial."); q.readPolynomial(kb); r = Polynomial.add(p,q); System.out.println(); System.out.print("The sum of "); p.display(); System.out.print(" and "); q.display(); System.out.print(" is "); r.display(); } }

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• Need help with implementing collision detection using the Separating Axis Theorem

  - by Eddie Ringle

  So, after hours of Googling and reading, I've found that the basic process of detecting a collision using SAT is: for each edge of poly A project A and B onto the normal for this edge if intervals do not overlap, return false end for for each edge of poly B project A and B onto the normal for this edge if intervals do not overlap, return false end for However, as many ways as I try to implement this in code, I just cannot get it to detect the collision. My current code is as follows: for (unsigned int i = 0; i < asteroids.size(); i++) { if (asteroids.valid(i)) { asteroids[i]->Update(); // Player-Asteroid collision detection bool collision = true; SDL_Rect asteroidBox = asteroids[i]->boundingBox; // Bullet-Asteroid collision detection for (unsigned int j = 0; j < player.bullets.size(); j++) { if (player.bullets.valid(j)) { Bullet b = player.bullets[j]; collision = true; if (b.x + (b.w / 2.0f) < asteroidBox.x - (asteroidBox.w / 2.0f)) collision = false; if (b.x - (b.w / 2.0f) > asteroidBox.x + (asteroidBox.w / 2.0f)) collision = false; if (b.y - (b.h / 2.0f) > asteroidBox.y + (asteroidBox.h / 2.0f)) collision = false; if (b.y + (b.h / 2.0f) < asteroidBox.y - (asteroidBox.h / 2.0f)) collision = false; if (collision) { bool realCollision = false; float min1, max1, min2, max2; // Create a list of vertices for the bullet CrissCross::Data::LList<Vector2D *> bullVerts; bullVerts.insert(new Vector2D(b.x - b.w / 2.0f, b.y + b.h / 2.0f)); bullVerts.insert(new Vector2D(b.x - b.w / 2.0f, b.y - b.h / 2.0f)); bullVerts.insert(new Vector2D(b.x + b.w / 2.0f, b.y - b.h / 2.0f)); bullVerts.insert(new Vector2D(b.x + b.w / 2.0f, b.y + b.h / 2.0f)); // Create a list of vectors of the edges of the bullet and the asteroid CrissCross::Data::LList<Vector2D *> bullEdges; CrissCross::Data::LList<Vector2D *> asteroidEdges; for (int k = 0; k < 4; k++) { int n = (k == 3) ? 0 : k + 1; bullEdges.insert(new Vector2D(bullVerts[k]->x - bullVerts[n]->x, bullVerts[k]->y - bullVerts[n]->y)); asteroidEdges.insert(new Vector2D(asteroids[i]->vertices[k]->x - asteroids[i]->vertices[n]->x, asteroids[i]->vertices[k]->y - asteroids[i]->vertices[n]->y)); } for (unsigned int k = 0; k < asteroidEdges.size(); k++) { Vector2D *axis = asteroidEdges[k]->getPerpendicular(); min1 = max1 = axis->dotProduct(asteroids[i]->vertices[0]); for (unsigned int l = 1; l < asteroids[i]->vertices.size(); l++) { float test = axis->dotProduct(asteroids[i]->vertices[l]); min1 = (test < min1) ? test : min1; max1 = (test > max1) ? test : max1; } min2 = max2 = axis->dotProduct(bullVerts[0]); for (unsigned int l = 1; l < bullVerts.size(); l++) { float test = axis->dotProduct(bullVerts[l]); min2 = (test < min2) ? test : min2; max2 = (test > max2) ? test : max2; } delete axis; axis = NULL; if ( (min1 - max2) > 0 || (min2 - max1) > 0 ) { realCollision = false; break; } else { realCollision = true; } } if (realCollision == false) { for (unsigned int k = 0; k < bullEdges.size(); k++) { Vector2D *axis = bullEdges[k]->getPerpendicular(); min1 = max1 = axis->dotProduct(asteroids[i]->vertices[0]); for (unsigned int l = 1; l < asteroids[i]->vertices.size(); l++) { float test = axis->dotProduct(asteroids[i]->vertices[l]); min1 = (test < min1) ? test : min1; max1 = (test > max1) ? test : max1; } min2 = max2 = axis->dotProduct(bullVerts[0]); for (unsigned int l = 1; l < bullVerts.size(); l++) { float test = axis->dotProduct(bullVerts[l]); min2 = (test < min2) ? test : min2; max2 = (test > max2) ? test : max2; } delete axis; axis = NULL; if ( (min1 - max2) > 0 || (min2 - max1) > 0 ) { realCollision = false; break; } else { realCollision = true; } } } if (realCollision) { player.bullets.remove(j); int numAsteroids; float newDegree; srand ( j + asteroidBox.x ); if ( asteroids[i]->degree == 90.0f ) { if ( rand() % 2 == 1 ) { numAsteroids = 3; newDegree = 30.0f; } else { numAsteroids = 2; newDegree = 45.0f; } for ( int k = 0; k < numAsteroids; k++) asteroids.insert(new Asteroid(asteroidBox.x + (10 * k), asteroidBox.y + (10 * k), newDegree)); } delete asteroids[i]; asteroids.remove(i); } while (bullVerts.size()) { delete bullVerts[0]; bullVerts.remove(0); } while (bullEdges.size()) { delete bullEdges[0]; bullEdges.remove(0); } while (asteroidEdges.size()) { delete asteroidEdges[0]; asteroidEdges.remove(0); } } } } } } bullEdges is a list of vectors of the edges of a bullet, asteroidEdges is similar, and bullVerts and asteroids[i].vertices are, obviously, lists of vectors of each vertex for the respective bullet or asteroid. Honestly, I'm not looking for code corrections, just a fresh set of eyes.

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• How to fix "BASIC runtime error 1; Type: com.sun.star.uno.Runtime Exception, Message: Toolbar do not exist " error in Libreoffice calc, Ubuntu 12.04

  - by PDeb

  I get the following error while openning a .xls file in Libreoffice Calc, Ubuntu 12.04 [LibreOffice 3.5.5.2; Build ID: 350m 1 (Build:2)] To overcome this I checked the LibreOffice Security Level to Low under Macro Security (from Tools---- Options--- Security tab. Then I went ahead intalling java by running the following commands from the terminal window (with some tips from various forums) sudo add-apt-repository ppa:libreoffice/ppa sudo apt-get update sudo apt-get install libreoffice libreoffice-java-common libreoffice-math libreoffice-gnome libreoffice-java-common Still I got the BASIC runtime error (as in the title), even after clicking Tools---- Options ---- Java and checking the 'Use a Java runtime environment option' and then clicking on 'Sun Microsystems Inc' under listed JRE environments installed. Even I ran the following commands to install latest Java run time environments from terminal window sudo apt-get install openjdk-7-jre icedtea-7-plugin But still I get the same Basicruntime error (details as in the title bar). This particular file opens perfectly in Microsoft Excel 2007, in Win XP Professional.

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• Status of stack based languages

  - by Andrea

  I have recently become curious about Factor, which, as far as I understand, is the most practical stack based language around. Forth seems not to be used much these days - I think it is because it was meant to be used on its own, instead of inside an operating system, although ports of course exist. It is also pretty low level. Joy is essentially dead, as the author stated that it does not make sense to mantain it in spite of adopting Factor. The fact is that Factor itself does not seem much developed today. The GitHub repo does not seem very active, and a lot of stuff languishes in unmantained. So, are there any other languages of this type that are more actively mantained? Are any in production use?

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• Hekaton – SQL Server’s in-memory database engine

  - by Christian

  Microsoft have just gone public at the PASS Summit in Seattle about a new SQL Server engine that they’re working on which is optimized for high-memory servers – an in-memory OLTP database engine which is built-in to SQL Server rather than a separate entity.  This means that you can move just the performance critical parts of your database to Hekaton. The new engine really pushes the performance boundaries by eliminating as many instructions as possible: Main memory optimized tables which are decoupled from on-disk structures; Everything is lock and latch free; More work is pushed to compile time so your T-SQL code is compiled natively into low-level code. We’re already working with a customer on an early adoption program so expect to hear from us on what we learn about implementing it!   Christian Bolton - MCA, MCM, MVP Technical Director http://coeo.com - SQL Server Consulting & Managed Services

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• HSDPA modem only working on certain USB ports

  - by nabulke

  Depending on which USB port I use to connect my HSDPA modem, the network manager will connect to the internet or not. I used to work (i.e. established a internet connection automatically) on all ports, but over time it simply stopped on some ports. lsusb output in all cases looks like that (Device ID varies depending on USB port): Bus 001 Device 009: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem Any ideas what could cause this behaviour? What can I do to fix this? ADDED One additional information about the modem: if connected via USB it will be available as as harddrive AND as a HSDPA modem (kind of a duality...). In the error case, it will only be shown as a harddrive. ADDITIONAL INFO AS REQUESTED MODEM NOT WORKING Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 002: ID 413c:8000 Dell Computer Corp. BC02 Bluetooth Adapter Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 007: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem Bus 001 Device 005: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse Bus 001 Device 004: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB Bus 001 Device 003: ID 413c:0058 Dell Computer Corp. Port Replicator Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub laptop:~$ dmesg | grep 'usb' [ 0.225371] usbcore: registered new interface driver usbfs [ 0.225387] usbcore: registered new interface driver hub [ 0.225418] usbcore: registered new device driver usb [ 0.504291] usb usb1: configuration #1 chosen from 1 choice [ 0.504767] usb usb2: configuration #1 chosen from 1 choice [ 0.505046] usb usb3: configuration #1 chosen from 1 choice [ 0.505601] usb usb4: configuration #1 chosen from 1 choice [ 1.061064] usb 1-6: new high speed USB device using ehci_hcd and address 3 [ 1.192636] usb 1-6: configuration #1 chosen from 1 choice [ 1.447006] usb 2-2: new full speed USB device using uhci_hcd and address 2 [ 1.634908] usb 2-2: configuration #1 chosen from 1 choice [ 1.708164] usb 1-6.1: new high speed USB device using ehci_hcd and address 4 [ 1.801668] usb 1-6.1: configuration #1 chosen from 1 choice [ 2.076279] usb 1-6.1.1: new low speed USB device using ehci_hcd and address 5 [ 2.174932] usb 1-6.1.1: configuration #1 chosen from 1 choice [ 6.580315] usb 1-6.1.2: new high speed USB device using ehci_hcd and address6 [ 6.683479] usb 1-6.1.2: configuration #1 chosen from 1 choice [ 20.018671] usbcore: registered new interface driver btusb [ 20.131703] usbcore: registered new interface driver usb-storage [ 20.131988] usb-storage: device found at 6 [ 20.131991] usb-storage: waiting for device to settle before scanning [ 20.207981] usb 1-6.1.2: USB disconnect, address 6 [ 20.291499] usbcore: registered new interface driver hiddev [ 20.297052] input: Logitech USB Mouse as /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6.1/1-6.1.1/1-6.1.1:1.0/input/input6 [ 20.297465] generic-usb 0003:046D:C00C.0001: input,hidraw0: USB HID v1.10 Mouse [Logitech USB Mouse] on usb-0000:00:1d.7-6.1.1/input0 [ 20.297534] usbcore: registered new interface driver usbhid [ 20.297803] usbhid: v2.6:USB HID core driver [ 26.552360] usb 1-6.1.2: new high speed USB device using ehci_hcd and address 7 [ 26.663506] usb 1-6.1.2: configuration #1 chosen from 1 choice [ 26.709628] usb-storage: device found at 7 [ 26.709631] usb-storage: waiting for device to settle before scanning [ 26.732387] usb-storage: device found at 7 [ 26.732390] usb-storage: waiting for device to settle before scanning [ 31.709568] usb-storage: device scan complete [ 31.733676] usb-storage: device scan complete MODEM WORKING Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 002: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 002: ID 413c:8000 Dell Computer Corp. BC02 Bluetooth Adapter Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 004: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub dmesg | grep 'usb' [ 0.134811] usbcore: registered new interface driver usbfs [ 0.134826] usbcore: registered new interface driver hub [ 0.134858] usbcore: registered new device driver usb [ 0.360327] usb usb1: configuration #1 chosen from 1 choice [ 0.360783] usb usb2: configuration #1 chosen from 1 choice [ 0.361061] usb usb3: configuration #1 chosen from 1 choice [ 0.361611] usb usb4: configuration #1 chosen from 1 choice [ 1.144122] usb 2-2: new full speed USB device using uhci_hcd and address 2 [ 1.346896] usb 2-2: configuration #1 chosen from 1 choice [ 1.588072] usb 3-1: new low speed USB device using uhci_hcd and address 2 [ 1.761204] usb 3-1: configuration #1 chosen from 1 choice [ 5.972042] usb 1-1: new high speed USB device using ehci_hcd and address 4 [ 6.115438] usb 1-1: configuration #1 chosen from 1 choice [ 19.990565] usbcore: registered new interface driver usbserial [ 19.991429] usb-storage: device found at 4 [ 19.991432] usb-storage: waiting for device to settle before scanning [ 20.017260] usbcore: registered new interface driver usb-storage [ 20.017305] usbcore: registered new interface driver usbserial_generic [ 20.017308] usbserial: USB Serial Driver core [ 20.017817] usb-storage: device found at 4 [ 20.017820] usb-storage: waiting for device to settle before scanning [ 20.070796] usbcore: registered new interface driver btusb [ 20.229525] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0 [ 20.229776] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1 [ 20.229843] usbcore: registered new interface driver option [ 20.230396] usbcore: registered new interface driver hiddev [ 20.246280] input: Logitech USB Mouse as /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/input/input6 [ 20.246438] generic-usb 0003:046D:C00C.0001: input,hidraw0: USB HID v1.10 Mouse [Logitech USB Mouse] on usb-0000:00:1d.1-1/input0 [ 20.246479] usbcore: registered new interface driver usbhid [ 20.246483] usbhid: v2.6:USB HID core driver [ 25.436579] usb-storage: device scan complete [ 25.437674] usb-storage: device scan complete

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• WebLogic Server Performance and Tuning: Part I - Tuning JVM

  - by Gokhan Gungor

  Each WebLogic Server instance runs in its own dedicated Java Virtual Machine (JVM) which is their runtime environment. Every Admin Server in any domain executes within a JVM. The same also applies for Managed Servers. WebLogic Server can be used for a wide variety of applications and services which uses the same runtime environment and resources. Oracle WebLogic ships with 2 different JVM, HotSpot and JRocket but you can choose which JVM you want to use. JVM is designed to optimize itself however it also provides some startup options to make small changes. There are default values for its memory and garbage collection. In real world, you will not want to stick with the default values provided by the JVM rather want to customize these values based on your applications which can produce large gains in performance by making small changes with the JVM parameters. We can tell the garbage collector how to delete garbage and we can also tell JVM how much space to allocate for each generation (of java Objects) or for heap. Remember during the garbage collection no other process is executed within the JVM or runtime, which is called STOP THE WORLD which can affect the overall throughput. Each JVM has its own memory segment called Heap Memory which is the storage for java Objects. These objects can be grouped based on their age like young generation (recently created objects) or old generation (surviving objects that have lived to some extent), etc. A java object is considered garbage when it can no longer be reached from anywhere in the running program. Each generation has its own memory segment within the heap. When this segment gets full, garbage collector deletes all the objects that are marked as garbage to create space. When the old generation space gets full, the JVM performs a major collection to remove the unused objects and reclaim their space. A major garbage collect takes a significant amount of time and can affect system performance. When we create a managed server either on the same machine or on remote machine it gets its initial startup parameters from $DOMAIN_HOME/bin/setDomainEnv.sh/cmd file. By default two parameters are set:     Xms: The initial heapsize     Xmx: The max heapsize Try to set equal initial and max heapsize. The startup time can be a little longer but for long running applications it will provide a better performance. When we set -Xms512m -Xmx1024m, the physical heap size will be 512m. This means that there are pages of memory (in the state of the 512m) that the JVM does not explicitly control. It will be controlled by OS which could be reserve for the other tasks. In this case, it is an advantage if the JVM claims the entire memory at once and try not to spend time to extend when more memory is needed. Also you can use -XX:MaxPermSize (Maximum size of the permanent generation) option for Sun JVM. You should adjust the size accordingly if your application dynamically load and unload a lot of classes in order to optimize the performance. You can set the JVM options/heap size from the following places:     Through the Admin console, in the Server start tab     In the startManagedWeblogic script for the managed servers     $DOMAIN_HOME/bin/startManagedWebLogic.sh/cmd     JAVA_OPTIONS="-Xms1024m -Xmx1024m" ${JAVA_OPTIONS}     In the setDomainEnv script for the managed servers and admin server (domain wide)     USER_MEM_ARGS="-Xms1024m -Xmx1024m" When there is free memory available in the heap but it is too fragmented and not contiguously located to store the object or when there is actually insufficient memory we can get java.lang.OutOfMemoryError. We should create Thread Dump and analyze if that is possible in case of such error. The second option we can use to produce higher throughput is to garbage collection. We can roughly divide GC algorithms into 2 categories: parallel and concurrent. Parallel GC stops the execution of all the application and performs the full GC, this generally provides better throughput but also high latency using all the CPU resources during GC. Concurrent GC on the other hand, produces low latency but also low throughput since it performs GC while application executes. The JRockit JVM provides some useful command-line parameters that to control of its GC scheme like -XgcPrio command-line parameter which takes the following options; XgcPrio:pausetime (To minimize latency, parallel GC) XgcPrio:throughput (To minimize throughput, concurrent GC ) XgcPrio:deterministic (To guarantee maximum pause time, for real time systems) Sun JVM has similar parameters (like  -XX:UseParallelGC or -XX:+UseConcMarkSweepGC) to control its GC scheme. We can add -verbosegc -XX:+PrintGCDetails to monitor indications of a problem with garbage collection. Try configuring JVM’s of all managed servers to execute in -server mode to ensure that it is optimized for a server-side production environment.

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• Simple Java networking game engine [on hold]

  - by Florian Peschka

  I want to create a simple java networking game and search a networking engine that eases use of sockets etc. I have already read some questions on here and the internet about java networking for games, but many of them were over 10 years old or not really answered. I have no idea whatsoever about what exactly I need to send in terms of messages, but I figured simple strings or integers will be enough for my purposes. It's basically a peer to peer game, so I don't need a centralized server structure. Messaging doesn't have to have an extremely low ping, yet of course all players need to have a synchronized view. What are the possibilities I have here?

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• What You Said: What’s on Your Geeky Christmas List

  - by Jason Fitzpatrick

  Earlier this week we asked you to share what’s on your geeky Christmas list; you responded and we’re back to share your longed for tech goodies. The most requested item was this year’s hot introduction to the project board market: the Raspberry Pi. Dave writes: A Rapsberry Pi to tinker with, especially to see if I can get it up and running with OpenElec/Raspbmc and a torrent client for a low power media centre/htpc We just finished setting up a batch of new 512MB Raspberry Pi systems running the newest release of Rasbmbc and can’t recommend it enough–new refinements in Raspbmc and the extra 256MB of RAM really improve the media center experience. All John wants is a real keyboard so he can escape the torture of using a touch screen: How to Factory Reset Your Android Phone or Tablet When It Won’t Boot Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode

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• Is there any good tutorial on Apache Jelly?

  - by Vigneshwaran

  I want to write a Jenkins Plugin which requires some knowledge on Apache Jelly. I looked at the Apache Site. It says "Low activity of developers" at the top. They have this tutorial page http://commons.apache.org/jelly/tutorial.html If I click any link to sample code, it gives me a 404 Not Found error. I couldn't find any other tutorial. Please point me to a good tutorial if there is any. Thanks a lot. (PS. Please add Tag Jelly)

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• NoSQL Memcached API for MySQL: Latest Updates

  - by Mat Keep

  With data volumes exploding, it is vital to be able to ingest and query data at high speed. For this reason, MySQL has implemented NoSQL interfaces directly to the InnoDB and MySQL Cluster (NDB) storage engines, which bypass the SQL layer completely. Without SQL parsing and optimization, Key-Value data can be written directly to MySQL tables up to 9x faster, while maintaining ACID guarantees. In addition, users can continue to run complex queries with SQL across the same data set, providing real-time analytics to the business or anonymizing sensitive data before loading to big data platforms such as Hadoop, while still maintaining all of the advantages of their existing relational database infrastructure. This and more is discussed in the latest Guide to MySQL and NoSQL where you can learn more about using the APIs to scale new generations of web, cloud, mobile and social applications on the world's most widely deployed open source database The native Memcached API is part of the MySQL 5.6 Release Candidate, and is already available in the GA release of MySQL Cluster. By using the ubiquitous Memcached API for writing and reading data, developers can preserve their investments in Memcached infrastructure by re-using existing Memcached clients, while also eliminating the need for application changes. Speed, when combined with flexibility, is essential in the world of growing data volumes and variability. Complementing NoSQL access, support for on-line DDL (Data Definition Language) operations in MySQL 5.6 and MySQL Cluster enables DevOps teams to dynamically update their database schema to accommodate rapidly changing requirements, such as the need to capture additional data generated by their applications. These changes can be made without database downtime. Using the Memcached interface, developers do not need to define a schema at all when using MySQL Cluster. Lets look a little more closely at the Memcached implementations for both InnoDB and MySQL Cluster. Memcached Implementation for InnoDB The Memcached API for InnoDB is previewed as part of the MySQL 5.6 Release Candidate. As illustrated in the following figure, Memcached for InnoDB is implemented via a Memcached daemon plug-in to the mysqld process, with the Memcached protocol mapped to the native InnoDB API. Figure 1: Memcached API Implementation for InnoDB With the Memcached daemon running in the same process space, users get very low latency access to their data while also leveraging the scalability enhancements delivered with InnoDB and a simple deployment and management model. Multiple web / application servers can remotely access the Memcached / InnoDB server to get direct access to a shared data set. With simultaneous SQL access, users can maintain all the advanced functionality offered by InnoDB including support for Foreign Keys, XA transactions and complex JOIN operations. Benchmarks demonstrate that the NoSQL Memcached API for InnoDB delivers up to 9x higher performance than the SQL interface when inserting new key/value pairs, with a single low-end commodity server supporting nearly 70,000 Transactions per Second. Figure 2: Over 9x Faster INSERT Operations The delivered performance demonstrates MySQL with the native Memcached NoSQL interface is well suited for high-speed inserts with the added assurance of transactional guarantees. You can check out the latest Memcached / InnoDB developments and benchmarks here You can learn how to configure the Memcached API for InnoDB here Memcached Implementation for MySQL Cluster Memcached API support for MySQL Cluster was introduced with General Availability (GA) of the 7.2 release, and joins an extensive range of NoSQL interfaces that are already available for MySQL Cluster Like Memcached, MySQL Cluster provides a distributed hash table with in-memory performance. MySQL Cluster extends Memcached functionality by adding support for write-intensive workloads, a full relational model with ACID compliance (including persistence), rich query support, auto-sharding and 99.999% availability, with extensive management and monitoring capabilities. All writes are committed directly to MySQL Cluster, eliminating cache invalidation and the overhead of data consistency checking to ensure complete synchronization between the database and cache. Figure 3: Memcached API Implementation with MySQL Cluster Implementation is simple: 1. The application sends reads and writes to the Memcached process (using the standard Memcached API). 2. This invokes the Memcached Driver for NDB (which is part of the same process) 3. The NDB API is called, providing for very quick access to the data held in MySQL Cluster’s data nodes. The solution has been designed to be very flexible, allowing the application architect to find a configuration that best fits their needs. It is possible to co-locate the Memcached API in either the data nodes or application nodes, or alternatively within a dedicated Memcached layer. The benefit of this flexible approach to deployment is that users can configure behavior on a per-key-prefix basis (through tables in MySQL Cluster) and the application doesn’t have to care – it just uses the Memcached API and relies on the software to store data in the right place(s) and to keep everything synchronized. Using Memcached for Schema-less Data By default, every Key / Value is written to the same table with each Key / Value pair stored in a single row – thus allowing schema-less data storage. Alternatively, the developer can define a key-prefix so that each value is linked to a pre-defined column in a specific table. Of course if the application needs to access the same data through SQL then developers can map key prefixes to existing table columns, enabling Memcached access to schema-structured data already stored in MySQL Cluster. Conclusion Download the Guide to MySQL and NoSQL to learn more about NoSQL APIs and how you can use them to scale new generations of web, cloud, mobile and social applications on the world's most widely deployed open source database See how to build a social app with MySQL Cluster and the Memcached API from our on-demand webinar or take a look at the docs Don't hesitate to use the comments section below for any questions you may have 

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• How can I find the approximate daily traffic of a site which I don't own?

  - by John Thomas

  I want to find the approximate daily traffic of a site which isn't ours, and the site is located in other country than US (in Greece - hence no Quantcast or Compete.com afaik) and it doesn't use Google Ads (hence no Google Ad Planner). I know about Alexa but the site(s) has/have relatively low traffic and the Alexa's rank isn't very useful (same stands to Google Trends). Or perhaps I should look more at Alexa's data? Any other ideas? PS: I looked before posting here and here. No luck.

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• NET Math Libraries

  - by JoshReuben

  NET Mathematical Libraries   .NET Builder for Matlab The MathWorks Inc. - http://www.mathworks.com/products/netbuilder/ MATLAB Builder NE generates MATLAB based .NET and COM components royalty-free deployment creates the components by encrypting MATLAB functions and generating either a .NET or COM wrapper around them. .NET/Link for Mathematica www.wolfram.com a product that 2-way integrates Mathematica and Microsoft's .NET platform call .NET from Mathematica - use arbitrary .NET types directly from the Mathematica language. use and control the Mathematica kernel from a .NET program. turns Mathematica into a scripting shell to leverage the computational services of Mathematica. write custom front ends for Mathematica or use Mathematica as a computational engine for another program comes with full source code. Leverages MathLink - a Wolfram Research's protocol for sending data and commands back and forth between Mathematica and other programs. .NET/Link abstracts the low-level details of the MathLink C API. Extreme Optimization http://www.extremeoptimization.com/ a collection of general-purpose mathematical and statistical classes built for the.NET framework. It combines a math library, a vector and matrix library, and a statistics library in one package. download the trial of version 4.0 to try it out. Multi-core ready - Full support for Task Parallel Library features including cancellation. Broad base of algorithms covering a wide range of numerical techniques, including: linear algebra (BLAS and LAPACK routines), numerical analysis (integration and differentiation), equation solvers. Mathematics leverages parallelism using .NET 4.0's Task Parallel Library. Basic math: Complex numbers, 'special functions' like Gamma and Bessel functions, numerical differentiation. Solving equations: Solve equations in one variable, or solve systems of linear or nonlinear equations. Curve fitting: Linear and nonlinear curve fitting, cubic splines, polynomials, orthogonal polynomials. Optimization: find the minimum or maximum of a function in one or more variables, linear programming and mixed integer programming. Numerical integration: Compute integrals over finite or infinite intervals, over 2D and higher dimensional regions. Integrate systems of ordinary differential equations (ODE's). Fast Fourier Transforms: 1D and 2D FFT's using managed or fast native code (32 and 64 bit) BigInteger, BigRational, and BigFloat: Perform operations with arbitrary precision. Vector and Matrix Library Real and complex vectors and matrices. Single and double precision for elements. Structured matrix types: including triangular, symmetrical and band matrices. Sparse matrices. Matrix factorizations: LU decomposition, QR decomposition, singular value decomposition, Cholesky decomposition, eigenvalue decomposition. Portability and performance: Calculations can be done in 100% managed code, or in hand-optimized processor-specific native code (32 and 64 bit). Statistics Data manipulation: Sort and filter data, process missing values, remove outliers, etc. Supports .NET data binding. Statistical Models: Simple, multiple, nonlinear, logistic, Poisson regression. Generalized Linear Models. One and two-way ANOVA. Hypothesis Tests: 12 14 hypothesis tests, including the z-test, t-test, F-test, runs test, and more advanced tests, such as the Anderson-Darling test for normality, one and two-sample Kolmogorov-Smirnov test, and Levene's test for homogeneity of variances. Multivariate Statistics: K-means cluster analysis, hierarchical cluster analysis, principal component analysis (PCA), multivariate probability distributions. Statistical Distributions: 25 29 continuous and discrete statistical distributions, including uniform, Poisson, normal, lognormal, Weibull and Gumbel (extreme value) distributions. Random numbers: Random variates from any distribution, 4 high-quality random number generators, low discrepancy sequences, shufflers. New in version 4.0 (November, 2010) Support for .NET Framework Version 4.0 and Visual Studio 2010 TPL Parallellized – multicore ready sparse linear program solver - can solve problems with more than 1 million variables. Mixed integer linear programming using a branch and bound algorithm. special functions: hypergeometric, Riemann zeta, elliptic integrals, Frensel functions, Dawson's integral. Full set of window functions for FFT's. Product  Price Update subscription Single Developer License $999  $399  Team License (3 developers) $1999  $799  Department License (8 developers) $3999  $1599  Site License (Unlimited developers in one physical location) $7999  $3199    NMath http://www.centerspace.net .NET math and statistics libraries matrix and vector classes random number generators Fast Fourier Transforms (FFTs) numerical integration linear programming linear regression curve and surface fitting optimization hypothesis tests analysis of variance (ANOVA) probability distributions principal component analysis cluster analysis built on the Intel Math Kernel Library (MKL), which contains highly-optimized, extensively-threaded versions of BLAS (Basic Linear Algebra Subroutines) and LAPACK (Linear Algebra PACKage). Product  Price Update subscription Single Developer License $1295 $388 Team License (5 developers) $5180 $1554   DotNumerics http://www.dotnumerics.com/NumericalLibraries/Default.aspx free DotNumerics is a website dedicated to numerical computing for .NET that includes a C# Numerical Library for .NET containing algorithms for Linear Algebra, Differential Equations and Optimization problems. The Linear Algebra library includes CSLapack, CSBlas and CSEispack, ports from Fortran to C# of LAPACK, BLAS and EISPACK, respectively. Linear Algebra (CSLapack, CSBlas and CSEispack). Systems of linear equations, eigenvalue problems, least-squares solutions of linear systems and singular value problems. Differential Equations. Initial-value problem for nonstiff and stiff ordinary differential equations ODEs (explicit Runge-Kutta, implicit Runge-Kutta, Gear's BDF and Adams-Moulton). Optimization. Unconstrained and bounded constrained optimization of multivariate functions (L-BFGS-B, Truncated Newton and Simplex methods).   Math.NET Numerics http://numerics.mathdotnet.com/ free an open source numerical library - includes special functions, linear algebra, probability models, random numbers, interpolation, integral transforms. A merger of dnAnalytics with Math.NET Iridium in addition to a purely managed implementation will also support native hardware optimization. constants & special functions complex type support real and complex, dense and sparse linear algebra (with LU, QR, eigenvalues, ... decompositions) non-uniform probability distributions, multivariate distributions, sample generation alternative uniform random number generators descriptive statistics, including order statistics various interpolation methods, including barycentric approaches and splines numerical function integration (quadrature) routines integral transforms, like fourier transform (FFT) with arbitrary lengths support, and hartley spectral-space aware sequence manipulation (signal processing) combinatorics, polynomials, quaternions, basic number theory. parallelized where appropriate, to leverage multi-core and multi-processor systems fully managed or (if available) using native libraries (Intel MKL, ACMS, CUDA, FFTW) provides a native facade for F# developers

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• Wifi connection frequently dropping in hotspots and university campus, home Wifi works fine.

  - by Olivier Lalonde

  For some reason, my Wifi connection frequently drops everywhere except at home. I didn't have this problem with Windows 7 so I guess it's not a hardware problem. My best guess so far is that my connection timeout is very low so if my connection isn't able to reach the router after a few second, the connection drops. Is that likely to be the problem? If so, how could I fix this? Otherwise, what would be an alternative cause for this strange behavior?

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• Big Data – Role of Cloud Computing in Big Data – Day 11 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the NewSQL. In this article we will understand the role of Cloud in Big Data Story What is Cloud? Cloud is the biggest buzzword around from last few years. Everyone knows about the Cloud and it is extremely well defined online. In this article we will discuss cloud in the context of the Big Data. Cloud computing is a method of providing a shared computing resources to the application which requires dynamic resources. These resources include applications, computing, storage, networking, development and various deployment platforms. The fundamentals of the cloud computing are that it shares pretty much share all the resources and deliver to end users as a service.  Examples of the Cloud Computing and Big Data are Google and Amazon.com. Both have fantastic Big Data offering with the help of the cloud. We will discuss this later in this blog post. There are two different Cloud Deployment Models: 1) The Public Cloud and 2) The Private Cloud Public Cloud Public Cloud is the cloud infrastructure build by commercial providers (Amazon, Rackspace etc.) creates a highly scalable data center that hides the complex infrastructure from the consumer and provides various services. Private Cloud Private Cloud is the cloud infrastructure build by a single organization where they are managing highly scalable data center internally. Here is the quick comparison between Public Cloud and Private Cloud from Wikipedia:   Public Cloud Private Cloud Initial cost Typically zero Typically high Running cost Unpredictable Unpredictable Customization Impossible Possible Privacy No (Host has access to the data Yes Single sign-on Impossible Possible Scaling up Easy while within defined limits Laborious but no limits Hybrid Cloud Hybrid Cloud is the cloud infrastructure build with the composition of two or more clouds like public and private cloud. Hybrid cloud gives best of the both the world as it combines multiple cloud deployment models together. Cloud and Big Data – Common Characteristics There are many characteristics of the Cloud Architecture and Cloud Computing which are also essentially important for Big Data as well. They highly overlap and at many places it just makes sense to use the power of both the architecture and build a highly scalable framework. Here is the list of all the characteristics of cloud computing important in Big Data Scalability Elasticity Ad-hoc Resource Pooling Low Cost to Setup Infastructure Pay on Use or Pay as you Go Highly Available Leading Big Data Cloud Providers There are many players in Big Data Cloud but we will list a few of the known players in this list. Amazon Amazon is arguably the most popular Infrastructure as a Service (IaaS) provider. The history of how Amazon started in this business is very interesting. They started out with a massive infrastructure to support their own business. Gradually they figured out that their own resources are underutilized most of the time. They decided to get the maximum out of the resources they have and hence  they launched their Amazon Elastic Compute Cloud (Amazon EC2) service in 2006. Their products have evolved a lot recently and now it is one of their primary business besides their retail selling. Amazon also offers Big Data services understand Amazon Web Services. Here is the list of the included services: Amazon Elastic MapReduce – It processes very high volumes of data Amazon DynammoDB – It is fully managed NoSQL (Not Only SQL) database service Amazon Simple Storage Services (S3) – A web-scale service designed to store and accommodate any amount of data Amazon High Performance Computing – It provides low-tenancy tuned high performance computing cluster Amazon RedShift – It is petabyte scale data warehousing service Google Though Google is known for Search Engine, we all know that it is much more than that. Google Compute Engine – It offers secure, flexible computing from energy efficient data centers Google Big Query – It allows SQL-like queries to run against large datasets Google Prediction API – It is a cloud based machine learning tool Other Players Besides Amazon and Google we also have other players in the Big Data market as well. Microsoft is also attempting Big Data with the Cloud with Microsoft Azure. Additionally Rackspace and NASA together have initiated OpenStack. The goal of Openstack is to provide a massively scaled, multitenant cloud that can run on any hardware. Thing to Watch The cloud based solutions provides a great integration with the Big Data’s story as well it is very economical to implement as well. However, there are few things one should be very careful when deploying Big Data on cloud solutions. Here is a list of a few things to watch: Data Integrity Initial Cost Recurring Cost Performance Data Access Security Location Compliance Every company have different approaches to Big Data and have different rules and regulations. Based on various factors, one can implement their own custom Big Data solution on a cloud. Tomorrow In tomorrow’s blog post we will discuss about various Operational Databases supporting Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• CQRS - Benefits

  - by Dylan Smith

  Thanks to all the comments and feedback from the last post I think I have a better understanding now of the benefits of CQRS (separate from the benefits of Event Sourcing). I’m going to try and sum it up here, and point out some areas where I could still use some advice: CQRS Benefits Sounds like the primary benefit of CQRS as an architecture is it allows you to create a simpler domain model by sucking out everything related to queries. I can definitely see the benefit to this, in general the domain logic related to commands is the high-value behavior in the software, but the logic required to service the queries would add a lot of low-value “noise” to the domain model that would dilute the high-value (command) behavior – sorting, paging, filtering, pre-fetch paths, etc. Also the most appropriate domain structure for implementing commands might not be the most optimal for implementing queries. To paraphrase Greg, this usually results in a domain model that is mediocre at both, piss-poor at one, or more likely piss-poor at both commands and queries. Not only will you be able to simplify your domain model by pulling out all the query logic, but at least a handful of commands in most systems will probably be “pass-though” type commands with little to no logic that just generate events. If these can be implemented directly in the command-handler and never touch the domain model, this allows you to slim down the domain model even more. Also, if you were to do event sourcing without CQRS, you no longer have a database containing the current state (only the domain model would) which makes it difficult (or impossible) to support ad-hoc querying and/or reporting that is common in most business software. Of course CQRS provides some great scalability benefits, not only scalability but I have to assume that it provides extremely low latency for most operations, especially if you have an asynchronous event bus. I know Greg says that you get a 3x scaling (Commands, Queries, Client) of your ability to perform parallel development, but IMHO, it seems like it only provides 1.5x scaling since even without CQRS you’re going to have your client loosely coupled to your domain - which is still a great benefit to be able to realize. Questions / Concerns If all the queries against an aggregate get pulled out to the Query layer, what if the only commands for that aggregate can be handled in a “pass-through” manner with the command handler directly generating events. Is it possible to have an aggregate that isn’t modeled in the domain model? Are there any issues or downsides to this? I know in the feedback from my previous posts it was suggested that having one domain model handling both commands and queries requires implementing a lot of traversals between objects that wouldn’t be necessary if it was only servicing commands. My question is, do you include traversals in your domain model based on the needs of the code, or based on the conceptual domain model? If none of my Commands require a Customer.Orders traversal, but the conceptual domain includes the concept of a set of orders belonging to a customer – should I model that in my domain model or not? I like the idea of using the Query side of the architecture as a place to put junior devs where the risk of them screwing something up has minimal impact. But I’m not sold on the idea that you can actually outsource it. Like I said in one of my comments on my previous post, the code to handle a query and generate DTO’s is going to be dead simple, but the code to process events and apply them to the tables on the query side is going to require a significant amount of domain knowledge to know which events to listen for to update each of the de-normalized tables (and what changes need to be made when each event is processed). I don’t know about everybody else, but having Indian/Russian/whatever outsourced developers have to do anything that requires significant domain knowledge has never been successful in my experience. And if you need to spec out for each new query which events to listen to and what to do with each one, well that’s probably going to be just as much work to document as it would be to just implement it. Greg made the point in a comment that doing an aggregate query like “Total Sales By Customer” is going to be inefficient if you use event sourcing but not CQRS. I don’t understand why that would be the case. I imagine in that case you’d simply have a method/property on the Customer object that calculated total sales for that customer by enumerating over the Orders collection. Then the application services layer would generate DTO’s off of the Customers collection that included say the CustomerID, CustomerName, TotalSales, or whatever the case may be. As long as you use a snapshotting implementation, I don’t see why that would be anymore inefficient in a DDD+Event Sourcing implementation than in a typical DDD implementation. Like I mentioned in my last post I still have some questions about query logic that haven’t been answered yet, but before I start asking those I want to make sure I have a strong grasp on what benefits CQRS provides.  My main concern with the query logic was that I know I could just toss it all into the query side, but I was concerned that I would be losing the benefits of using CQRS in the first place if I did that.  I want to elaborate more on this though with some example situations in an upcoming post.

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• list of things to think about for hosting a potentially high traffic website

  - by SpashHit

  I do my own hosting for a few clients on my own VPS server (Lindode). Since my clients so far have been extremely low traffic, I have not had to really dig into some of the considerations that I would need for a higher traffic site. Now I am bidding on a client whose site will be potentially higher (not Facebook or twitter, but higher than Joe's ice cream shop). Is there a list of things I need to think about that I may be missing? I am going to assume, at least at first, that I will be able to handle them on my shared Linode, but I could move to a dedicated Linode if need be. I am not thinking so far of multiple servers, but short of that there are still considerations. For example, mod_perl instead of straight CGI, better backups, etc. What else? In case it matters, the stack will be debian-linux / apache / Perl / mysql / Template Toolkit.

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• Pyglet vs. PyQt

  - by L. De Leo

  I need to implement a really simple card game. As the game logic is written in Python I chose to stick with some Python framework even if my goal is to develop a Windows only version. I also don't like to work with .NET so I ruled out Iron Python + WPF. I tried to write a simple prototype with Pyglet but soon discovered that I will have to do a lot of stuff by hand: things like detecting mouseover events and finding which card was clicked on and moving it, etc... very low level and unnecessary for my use-case. So I thought it might be easier to do things in PyQt. Do you reckon it would be feasible to use PyQt for implementing a simple card game? Will I have higher level events I can work with?

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• Why isn't SSL/TLS built into modern Operating Systems?

  - by Channel72

  A lot of the basic network protocols that make up the infrastructure of the Internet are built in to most major Operating Systems. Things like TCP, UDP, and DNS are all built into Linux, UNIX and Windows, and are made available to the programmer through low-level system APIs. But when it comes to SSL or TLS, one has to turn to a third-party library such as OpenSSL or Mozilla NSS. SSL is a relatively old protocol, and it's basically an industry standard as ubiquitous as TCP/IP, so why isn't it built into most Operating Systems?

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• Can't Boot, video drivers or x-server problem?

  - by ZacharyH

  I was uninstalling some programs that I installed to try and get my iPod touch working with Ubuntu (I gave up on that) when ubuntu just crashed. Now after I choose ubuntu in GRUB, it gives me a screen that says "Ubuntu is running in low-graphics mode: your screen, graphics card, and input device settings could not be detected correctly. You will need to configure these yourself" It was working just fine before I started to uninstall those programs. I think that I might have uninstalled something necessary to the system. If I click OK on the screen, it gives me options to reconfigure, troubleshoot, exit to console, or restart X. But no matter what I choose I still can't boot into ubuntu - I get stuck looking at the splash screen which stalls forever. I was receiving support from one of my mate's and he was doing something with the LiveCD, and now the message doesn't pop up any more, I just get stuck at a never ending splash screen. Any help would be appreciated, thanks!

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• Managed Languages vs Compiled Language difference?

  - by l46kok

  I get confused when people try to make a distinction between compiled languages and managed languages. From experience, I understand that most consider compiled languages to be C,C++ while managed languages are Java,C# (There are obviously more, but these are just few examples). But what exactly is the core difference between the two types of languages? My understanding is that any program, regardless of what language you use is essentially "compiled" into a low-level machine code which is then interpreted, so does that kinda make managed languages a subset of compiled languages (That is, all managed languages are compiled languages but not the other way around)?

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• "Build your own website" - Developing a CMS with Vague Requirements on a Tight Deadline

  - by walnutmon

  I'm a Java developer in charge of making a product which allows clients to "build their own site". I've spent a lot of time looking into Liferay, as I don't have any experience in building CMSs, and want to either use it, or get ideas of how to build a decent system. The time line is short, requirements are vague, yada yada Is Liferay a good technology to work with when showing the client (who may be very low on computer expertise) a user interface to build a site? The thing is, I want the power and flexibility to avoid the learning curve in building a CMS like product, but I don't want to waste time learning a new technology only to find its over-kill, or can't do the simple - but uncommon and unimplemented - things that we are asked to add as features Ideally I'd like to provide multiple web interfaces to the core API to build the sites - one that is very powerful, and another that is watered down and easy to use.

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• Recommendation for a platform to teach game development to kids [closed]

  - by Moshe Kravchik

  My 11 years old son decided he want to create a Web game. He does not know much about programming and I never did any game development so I'm not the best teacher of the topic. On one hand I really want him to get into building things and doing his own game sounds perfect. So I'd like to find a way to keep him interested and progressing by himself. This means that I'm looking for a platform that is: 1. Simple for understanding and use, intuitive interface 2. Powerful 3. Good tools, preferrably free 4. Significant community for questions and tips 5. Localization - my son's English is quite poor (native Hebrew). We looked at Alice, but it was too limited in its abilities and isn't really a Web game building platform. HTML/CSS and Javascript - too low level for a kid to keep the interest. What would you recommend?

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