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  • Stack Overflow Error

    - by dylanisawesome1
    I recently created a recursive cave algorithm, and would like to have more extensive caves, but get a stack overflow after re-cursing a couple times. Any advice? Here's my code: for(int i=0;i<100;i++) { int rand = new Random().nextInt(100); if(rand<=20) { if(curtile.bounds.y-40>500+new Random().nextInt(20)) digDirection(Direction.UP); } if(rand<=40 && rand>20) { if(curtile.bounds.y+40<m.height) digDirection(Direction.DOWN); } if(rand<=60 && rand>40) { if(curtile.bounds.x-40>0) digDirection(Direction.LEFT); } if(rand<=80 && rand>60) { if(curtile.bounds.x+40<m.width) digDirection(Direction.RIGHT); } } } public void digDirection(Direction d) { if(new Random().nextInt(100)<=10) { new Miner(curtile, map); // try { // Thread.sleep(2); // } catch (InterruptedException e) { // // TODO Auto-generated catch block // e.printStackTrace(); // } //Tried this to avoid stack overflow. Didn't work. }

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  • Image with FadeIn effect blinks when added to scene

    - by Ef Es
    I am trying to add an image to the scene, but it should just be added to the scene invisible, FadeIn and then be deleted when the effect finishes. My problem is that the images blink once when they are added to the scene, then they do the intended effect. My best guess is that when they are added they show on the scene for a split second before starting the animation. I though of making them invisible for a split second before activating them, but I am not sure how to code it. const bool Sunbeams::add() { const CCSize kSceenSize = CCDirector::sharedDirector()->getWinSize(); const int nRayType = random( m_kRays.size()); const CCPoint kPosition( random( static_cast < int >( kSceenSize.width)), 0.0f); const float fDuration = random( m_fDurationVariance) + m_fDurationMin; CCSprite* pkLightBeam = CCSprite::spriteWithTexture( m_kRays[nRayType]); if ( !pkLightBeam) { msg::debug( "Sunbeams::add", "Failed to create sprite from ray '%d'!\n", m_kRays[nRayType]); return false; } pkLightBeam->setAnchorPoint( CCPointZero); pkLightBeam->setPosition( kPosition); m_kActiveBeams.push_back( pkLightBeam); CCDirector::sharedDirector()->getRunningScene()->addChild( pkLightBeam); CCActionInterval* pkAction = CCFadeIn::actionWithDuration( fDuration); CCActionInterval* pkActionBack = pkAction->reverse(); pkLightBeam->runAction( CCSequence::actions( pkAction, pkActionBack, 0)); return true; }

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  • How should developers handle subpar working conditions? [closed]

    - by ivar
    I have been working in my current job for less than a year and at the beginning didn't have the courage to say anything about the things that bothered me. Now I'm a bit fed up and need things to get better. The first problem is not random but I'll mention it anyway. We are running out of space so every new employee gets a smaller table. We are promised that the space problem will be fixed soon. Almost every employee has a different keyboard, mouse, headphones (if any). Mine are $10 keyboard, some random cheap mouse and some random crappy headphones with a mic. All these were used and dirty when I got them. The number of monitor is 1-3 and with different sizes. I have 2 nice monitors and can't complain but some are given 1 small monitor. When it's their first job they don't have the guts to ask for 2 even if most others have 2. Nobody seems to care too. Project manager asked if it's ok? He obviously said he can handle the 1 small one. Then the manager said you can go ask for 1 more. I'm watching this and think go and ask where? The company is trying to hire more people but is not doing much after the person has signed the contract. We are put in one room that is open to the hallway and it's super noisy. Almost like a zoo at times. Even if nobody is talking the crappy keyboards make too much noise. Is this normal? Am I too negative and should I just do my job with what I was given? Should I demand better things? Should the company have some system that everybody gets things in some price range?

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  • Fuzzing for Security

    - by Sylvain Duloutre
    Yesterday, I attended an internal workshop about ethical hacking. Hacking skills like fuzzing can be used to quantitatively assess and measure security threats in software.  Fuzzing is a software testing technique used to discover coding errors and security loopholes in software, operating systems or networks by injecting massive amounts of random data, called fuzz, to the system in an attempt to make it crash. If the program contains a vulnerability that can leads to an exception, crash or server error (in the case of web apps), it can be determined that a vulnerability has been discovered.A fuzzer is a program that generates and injects random (and in general faulty) input to an application. Its main purpose is to make things easier and automated.There are typically two methods for producing fuzz data that is sent to a target, Generation or Mutation. Generational fuzzers are capable of building the data being sent based on a data model provided by the fuzzer creator. Sometimes this is simple and dumb as sending random bytes, swapping bytes or much smarter by knowing good values and combining them in interesting ways.Mutation on the other hand starts out with a known good "template" which is then modified. However, nothing that is not present in the "template" or "seed" will be produced.Generally fuzzers are good at finding buffer overflow, DoS, SQL Injection, Format String bugs etc. They do a poor job at finding vulnerabilites related to information disclosure, encryption flaws and any other vulnerability that does not cause the program to crash.  Fuzzing is simple and offers a high benefit-to-cost ratio but does not replace other proven testing techniques.What is your computer doing over the week-end ?

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  • Model View Control Issue: Null Pointer Initialization Question

    - by David Dimalanta
    Good morning again. This is David. Please, I need an urgent help regarding control model view where I making a code that uniquely separating into groups: An Activity Java Class to Display the Interface A View and Function Java Class for Drawing Cards and Display it on the Activity Class The problem is that the result returns a Null Pointer Exception. I have initialize for the ID for Text View and Image View. Under this class "draw_deck.java". Please help me. Here's my code for draw_deck.java: package com.bodapps.inbetween.model; import android.content.Context; import android.view.View; import android.widget.ImageView; import android.widget.TextView; import com.bodapps.inbetween.R; public class draw_deck extends View { public TextView count_label; public ImageView draw_card; private int count; public draw_deck(Context context) { super(context); // TODO Auto-generated constructor stub //I have initialized two widgets for ID. I still don't get it why I got forced closed by Null Pointer Exception thing. draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); count_label = (TextView) findViewById(R.id.Text_View_Count_Card); } public void draw(int s, int c, String strSuit, String strValue, Pile pile, Context context) { //super(context); //Just printing the card drawn from pile int suit, value = 1; draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); count_label = (TextView) findViewById(R.id.Text_View_Count_Card); Card card; if(!pile.isEmpty()) //Setting it to IF statement displays the card one by one. { card = pile.drawFromPile(); //Need to check first if card is null. if (card != null) { //draws an extra if (card != null) { //Get suit of card to print out. suit = card.getSuit(); switch (suit) { case CardInfo.DIAMOND: strSuit = "DIAMOND"; s=0; break; case CardInfo.HEART: strSuit = "HEART"; s=1; break; case CardInfo.SPADE: strSuit = "SPADE"; s=2; break; case CardInfo.CLUB: strSuit = "CLUB"; s=3; break; } //Get value of card to print out. value = card.getValue(); switch (value) { case CardInfo.ACE: strValue = "ACE"; c=0; break; case CardInfo.TWO: c=1; break; case CardInfo.THREE: strValue = "THREE"; c=2; break; case CardInfo.FOUR: strValue = "FOUR"; c=3; break; case CardInfo.FIVE: strValue = "FIVE"; c=4; break; case CardInfo.SIX: strValue = "SIX"; c=4; break; case CardInfo.SEVEN: strValue = "SEVEN"; c=4; break; case CardInfo.EIGHT: strValue = "EIGHT"; c=4; break; case CardInfo.NINE: strValue = "NINE"; c=4; break; case CardInfo.TEN: strValue = "TEN"; c=4; break; case CardInfo.JACK: strValue = "JACK"; c=4; break; case CardInfo.QUEEN: strValue = "QUEEN"; c=4; break; case CardInfo.KING: strValue = "KING"; c=4; break; } } } }// //Below two lines of code, this is where issued the Null Pointer Exception. draw_card.setImageResource(deck[s][c]); count_label.setText(new StringBuilder(strValue).append(" of ").append(strSuit).append(String.valueOf(" " + count++)).toString()); } //Choice of Suits in a Deck public Integer[][] deck = { //Array Group 1 is [0][0] (No. of Cards: 4 - DIAMOND) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 2 is [1][0] (No. of Cards: 4 - HEART) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 3 is [2][0] (No. of Cards: 4 - SPADE) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 4 is [3][0] (No. of Cards: 4 - CLUB) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, }; } And this one of the activity class, Player_Mode_2.java: package com.bodapps.inbetween; import java.util.Random; import android.app.Activity; import android.app.Dialog; import android.content.Context; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.ImageView; import android.widget.TextView; import android.widget.Toast; import com.bodapps.inbetween.model.Card; import com.bodapps.inbetween.model.Pile; import com.bodapps.inbetween.model.draw_deck; /* * * Public class for Two-Player mode. * */ public class Player_Mode_2 extends Activity { //Image Views private ImageView draw_card; private ImageView player_1; private ImageView player_2; private ImageView icon; //Buttons private Button set_deck; //Edit Texts private EditText enter_no_of_decks; //text Views private TextView count_label; //Integer Data Types private int no_of_cards, count; private int card_multiplier; //Contexts final Context context = this; //Pile Model public Pile pile; //Card Model public Card card; //create View @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.play_2_player_mode); //-----[ Search for Views ]----- //Initialize for Image View draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); player_1 = (ImageView) findViewById(R.id.IV_Player_1_Card); player_2 = (ImageView) findViewById(R.id.IV_Player_2_Card); //Initialize for Text view or Label count_label = (TextView) findViewById(R.id.Text_View_Count_Card); //-----[ Adding Values ]----- //Integer Values count = 0; no_of_cards = 0; //-----[ Adding Dialog ]----- //Initializing Dialog final Dialog deck_dialog = new Dialog(context); deck_dialog.setContentView(R.layout.dialog); deck_dialog.setTitle("Deck Dialog"); //-----[ Initializing Views for Dialog's Contents ]----- //Initialize for Edit Text enter_no_of_decks = (EditText) deck_dialog.findViewById(R.id.Edit_Text_Set_Number_of_Decks); //Initialize for Button set_deck = (Button) deck_dialog.findViewById(R.id.Button_Deck); //-----[ Setting onClickListener() ]----- //Set Event Listener for Image view draw_card.setOnClickListener(new Draw_Card_Model()); //Set Event Listener for Setting the Deck set_deck.setOnClickListener(new OnClickListener() { public void onClick(View v) { if(card_multiplier <= 8) { //Use "Integer.parseInt()" method to instantly convert from String to int value. card_multiplier = Integer.parseInt(enter_no_of_decks.getText().toString()); //Shuffling cards... pile = new Pile(card_multiplier); //Multiply no. of decks //Dismiss or close the dialog. deck_dialog.dismiss(); } else { Toast.makeText(getApplicationContext(), "Please choose a number from 1 to 8.", Toast.LENGTH_SHORT).show(); } } }); //Show dialog. deck_dialog.show(); } //Shuffling the Array public void Shuffle_Cards(Integer[][] Shuffle_Deck) { Random random = new Random(); for(int i = Shuffle_Deck[no_of_cards].length - 1; i >=0; i--) { int Index = random.nextInt(i + 1); //Simple Swapping Integer swap = Shuffle_Deck[card_multiplier-1][Index]; Shuffle_Deck[card_multiplier-1][Index] = Shuffle_Deck[card_multiplier-1][i]; Shuffle_Deck[card_multiplier-1][i] = swap; } } //Private Class for Random Card Draw private class Draw_Card_Model implements OnClickListener { public void onClick(View v) { //Just printing the card drawn from pile int suit = 0, value = 0; String strSuit = "", strValue = ""; draw_deck draw = new draw_deck(context); //This line is where issued the Null Pointer Exception. if (count == card_multiplier*52) { // A message shows up when all cards are draw out. Toast.makeText(getApplicationContext(), "All cards have been used up.", Toast.LENGTH_SHORT).show(); draw_card.setEnabled(false); } else { draw.draw(suit, value, strSuit, strValue, pile, context); count_label.setText(count); //This is where I got force closed error, although "int count" have initialized the number. This was supposed to accept in the setText() method. count++; } } } } Take note that the issues on Null Pointer Exception is the Image View and the Edit Text. I got to test it. Thanks. If you have any info about my question, let me know it frankly.

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  • SQL SERVER – Using RAND() in User Defined Functions (UDF)

    - by pinaldave
    Here is the question I received in email. “Pinal, I am writing a function where we need to generate random password. While writing T-SQL I faced following issue. Everytime I tried to use RAND() function in my User Defined Function I am getting following error: Msg 443, Level 16, State 1, Procedure RandFn, Line 7 Invalid use of a side-effecting operator ‘rand’ within a function. Here is the simplified T-SQL code of the function which I am using: CREATE FUNCTION RandFn() RETURNS INT AS BEGIN DECLARE @rndValue INT SET @rndValue = RAND() RETURN @rndValue END GO I must use UDF so is there any workaround to use RAND function in UDF.” Here is the workaround how RAND() can be used in UDF. The scope of the blog post is not to discuss the advantages or disadvantages of the function or random function here but just to show how RAND() function can be used in UDF. RAND() function is directly not allowed to use in the UDF so we have to find alternate way to use the same function. This can be achieved by creating a VIEW which is using RAND() function and use the same VIEW in the UDF. Here is the step by step instructions. Create a VIEW using RAND function. CREATE VIEW rndView AS SELECT RAND() rndResult GO Create a UDF using the same VIEW. CREATE FUNCTION RandFn() RETURNS DECIMAL(18,18) AS BEGIN DECLARE @rndValue DECIMAL(18,18) SELECT @rndValue = rndResult FROM rndView RETURN @rndValue END GO Now execute the UDF and it will just work fine and return random result. SELECT dbo.RandFn() GO In T-SQL world, I have noticed that there are more than one solution to every problem. Is there any better solution to this question? Please post that question as a comment and I will include it with due credit. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: technology

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  • Model View Control Issue: Null Pointer Initialization Question [closed]

    - by David Dimalanta
    Good morning again. This is David. Please, I need an urgent help regarding control model view where I making a code that uniquely separating into groups: An Activity Java Class to Display the Interface A View and Function Java Class for Drawing Cards and Display it on the Activity Class The problem is that the result returns a Null Pointer Exception. I have initialize for the ID for Text View and Image View. Under this class "draw_deck.java". Please help me. Here's my code for draw_deck.java: package com.bodapps.inbetween.model; import android.content.Context; import android.view.View; import android.widget.ImageView; import android.widget.TextView; import com.bodapps.inbetween.R; public class draw_deck extends View { public TextView count_label; public ImageView draw_card; private int count; public draw_deck(Context context) { super(context); // TODO Auto-generated constructor stub //I have initialized two widgets for ID. I still don't get it why I got forced closed by Null Pointer Exception thing. draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); count_label = (TextView) findViewById(R.id.Text_View_Count_Card); } public void draw(int s, int c, String strSuit, String strValue, Pile pile, Context context) { //super(context); //Just printing the card drawn from pile int suit, value = 1; draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); count_label = (TextView) findViewById(R.id.Text_View_Count_Card); Card card; if(!pile.isEmpty()) //Setting it to IF statement displays the card one by one. { card = pile.drawFromPile(); //Need to check first if card is null. if (card != null) { //draws an extra if (card != null) { //Get suit of card to print out. suit = card.getSuit(); switch (suit) { case CardInfo.DIAMOND: strSuit = "DIAMOND"; s=0; break; case CardInfo.HEART: strSuit = "HEART"; s=1; break; case CardInfo.SPADE: strSuit = "SPADE"; s=2; break; case CardInfo.CLUB: strSuit = "CLUB"; s=3; break; } //Get value of card to print out. value = card.getValue(); switch (value) { case CardInfo.ACE: strValue = "ACE"; c=0; break; case CardInfo.TWO: c=1; break; case CardInfo.THREE: strValue = "THREE"; c=2; break; case CardInfo.FOUR: strValue = "FOUR"; c=3; break; case CardInfo.FIVE: strValue = "FIVE"; c=4; break; case CardInfo.SIX: strValue = "SIX"; c=4; break; case CardInfo.SEVEN: strValue = "SEVEN"; c=4; break; case CardInfo.EIGHT: strValue = "EIGHT"; c=4; break; case CardInfo.NINE: strValue = "NINE"; c=4; break; case CardInfo.TEN: strValue = "TEN"; c=4; break; case CardInfo.JACK: strValue = "JACK"; c=4; break; case CardInfo.QUEEN: strValue = "QUEEN"; c=4; break; case CardInfo.KING: strValue = "KING"; c=4; break; } } } }// //Below two lines of code, this is where issued the Null Pointer Exception. draw_card.setImageResource(deck[s][c]); count_label.setText(new StringBuilder(strValue).append(" of ").append(strSuit).append(String.valueOf(" " + count++)).toString()); } //Choice of Suits in a Deck public Integer[][] deck = { //Array Group 1 is [0][0] (No. of Cards: 4 - DIAMOND) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 2 is [1][0] (No. of Cards: 4 - HEART) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 3 is [2][0] (No. of Cards: 4 - SPADE) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 4 is [3][0] (No. of Cards: 4 - CLUB) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, }; } And this one of the activity class, Player_Mode_2.java: package com.bodapps.inbetween; import java.util.Random; import android.app.Activity; import android.app.Dialog; import android.content.Context; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.ImageView; import android.widget.TextView; import android.widget.Toast; import com.bodapps.inbetween.model.Card; import com.bodapps.inbetween.model.Pile; import com.bodapps.inbetween.model.draw_deck; /* * * Public class for Two-Player mode. * */ public class Player_Mode_2 extends Activity { //Image Views private ImageView draw_card; private ImageView player_1; private ImageView player_2; private ImageView icon; //Buttons private Button set_deck; //Edit Texts private EditText enter_no_of_decks; //text Views private TextView count_label; //Integer Data Types private int no_of_cards, count; private int card_multiplier; //Contexts final Context context = this; //Pile Model public Pile pile; //Card Model public Card card; //create View @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.play_2_player_mode); //-----[ Search for Views ]----- //Initialize for Image View draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); player_1 = (ImageView) findViewById(R.id.IV_Player_1_Card); player_2 = (ImageView) findViewById(R.id.IV_Player_2_Card); //Initialize for Text view or Label count_label = (TextView) findViewById(R.id.Text_View_Count_Card); //-----[ Adding Values ]----- //Integer Values count = 0; no_of_cards = 0; //-----[ Adding Dialog ]----- //Initializing Dialog final Dialog deck_dialog = new Dialog(context); deck_dialog.setContentView(R.layout.dialog); deck_dialog.setTitle("Deck Dialog"); //-----[ Initializing Views for Dialog's Contents ]----- //Initialize for Edit Text enter_no_of_decks = (EditText) deck_dialog.findViewById(R.id.Edit_Text_Set_Number_of_Decks); //Initialize for Button set_deck = (Button) deck_dialog.findViewById(R.id.Button_Deck); //-----[ Setting onClickListener() ]----- //Set Event Listener for Image view draw_card.setOnClickListener(new Draw_Card_Model()); //Set Event Listener for Setting the Deck set_deck.setOnClickListener(new OnClickListener() { public void onClick(View v) { if(card_multiplier <= 8) { //Use "Integer.parseInt()" method to instantly convert from String to int value. card_multiplier = Integer.parseInt(enter_no_of_decks.getText().toString()); //Shuffling cards... pile = new Pile(card_multiplier); //Multiply no. of decks //Dismiss or close the dialog. deck_dialog.dismiss(); } else { Toast.makeText(getApplicationContext(), "Please choose a number from 1 to 8.", Toast.LENGTH_SHORT).show(); } } }); //Show dialog. deck_dialog.show(); } //Shuffling the Array public void Shuffle_Cards(Integer[][] Shuffle_Deck) { Random random = new Random(); for(int i = Shuffle_Deck[no_of_cards].length - 1; i >=0; i--) { int Index = random.nextInt(i + 1); //Simple Swapping Integer swap = Shuffle_Deck[card_multiplier-1][Index]; Shuffle_Deck[card_multiplier-1][Index] = Shuffle_Deck[card_multiplier-1][i]; Shuffle_Deck[card_multiplier-1][i] = swap; } } //Private Class for Random Card Draw private class Draw_Card_Model implements OnClickListener { public void onClick(View v) { //Just printing the card drawn from pile int suit = 0, value = 0; String strSuit = "", strValue = ""; draw_deck draw = new draw_deck(context); //This line is where issued the Null Pointer Exception. if (count == card_multiplier*52) { // A message shows up when all cards are draw out. Toast.makeText(getApplicationContext(), "All cards have been used up.", Toast.LENGTH_SHORT).show(); draw_card.setEnabled(false); } else { draw.draw(suit, value, strSuit, strValue, pile, context); count_label.setText(count); //This is where I got force closed error, although "int count" have initialized the number. This was supposed to accept in the setText() method. count++; } } } } Take note that the issues on Null Pointer Exception is the Image View and the Edit Text. I got to test it. Thanks. If you have any info about my question, let me know it frankly.

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  • andEngine dynamic sprites

    - by Blucreation
    Ive just started with andEngine the past week and i only started learning java/android 3 weeks. I can use a for loop to add multiple sprites to the screen but when i try to check collisions on them it only does it to one and not the rest. I want to be able to add a specific number for sprites made from the same texture to the scene, add collision detection to them and also make them slide across the screen (im making a game where you avoid the obstacles). My simple code: private void createobstacle(float pX, float pY) { obstacle = new AnimatedSprite(pX, pY, this.mObjTextureRegion.deepCopy(), getVertexBufferObjectManager()); obstacle.setScale(MathUtils.random(0.5f, 3f)); scene.attachChild(obstacle); } private void createobstacle(int num) { for(int i=0; i<=num; i++ ) { final float xPos = MathUtils.random(30.0f, (CAMERA_WIDTH - 30.0f)); final float yPos = MathUtils.random(30.0f, (CAMERA_HEIGHT - 30.0f)); createobstacle(xPos, yPos); } } Ive read about arrays but i cannot find any tutorials about anything im stuck with. Any help would be great!

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  • What is the recommended MongoDB schema for this quiz-engine scenario?

    - by hughesdan
    I'm working on a quiz engine for learning a foreign language. The engine shows users four images simultaneously and then plays an audio file. The user has to match the audio to the correct image. Below is my MongoDB document structure. Each document consists of an image file reference and an array of references to audio files that match that image. To generate a quiz instance I select four documents at random, show the images and then play one audio file from the four documents at random. The next step in my application development is to decide on the best document schema for storing user guesses. There are several requirements to consider: I need to be able to report statistics at a user level. For example, total correct answers, total guesses, mean accuracy, etc) I need to be able to query images based on the user's learning progress. For example, select 4 documents where guess count is 10 and accuracy is <=0.50. The schema needs to be optimized for fast quiz generation. The schema must not cause future scaling issues vis a vis document size. Assume 1mm users who make an average of 1000 guesses. Given all of this as background information, what would be the recommended schema? For example, would you store each guess in the Image document or perhaps in a User document (not shown) or a new document collection created for logging guesses? Would you recommend logging the raw guess data or would you pre-compute statistics by incrementing counters within the relevant document? Schema for Image Collection: _id "505bcc7a45c978be24000005" date 2012-09-21 02:10:02 UTC imageFileName "BD3E134A-C7B3-4405-9004-ED573DF477FE-29879-0000395CF1091601" random 0.26997075392864645 user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioFiles [ 0 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "English" date 2012-09-22 01:15:04 UTC } 1 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "Spanish" date 2012-09-22 01:17:04 UTC } ]

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  • Testing my model for hybrid scheduling in Embedded Systems

    - by markusian
    I am working on a project for school, where I have to analyze the performances of a few fixed-priority servers algorithms (polling server, deferrable server, priority exchange) using a simulator in the case of hybrid scheduling, where we have both hard periodic tasks and soft aperiodic tasks. In my model I consider that: the hard tasks have a period equal to their deadline, with a known worst case execution time (wcet). The actual execution time could be smaller than the wcet. the soft tasks have a known wcet and random interarrival times. The actual execution time could be smaller than the wcet. In order to test those algorithms I need realistic case studies. For this reason I'm digging in the scientific literature but I am facing different problems: Sometimes I find a list of hard tasks with wcet, but it is not specified how the soft tasks parameters are found. Given the wcet of a task, how can I model its actual execution time? This means, what random distribution should I use considering the wcet? How can I model the random interarrival times of soft aperiodic tasks?

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  • How to load chunks of 2d map segments when player reaches a certain point?

    - by 2kan
    In my 2d platformer (made with Java and Slick2d), random maps are made by combining different segments together and displaying them one after the other. My problem is that I can't load too many segments or the game will run out of memory, so I want to load n number of segments at a time in chunks, then load the next chunk when the player comes near the end of one. I've attempted to do this for a couple of hours now, but I just can't get it to work at all. This is my chunk generation function where chunkLoad is the number of segments to load and BLOCK_WIDTH is the number of blocks/tiles each segment is across. Chunk1 and map are arrays of segments. Random r = new Random(); for(int i=0; i<chunkLoad; i++) { int id = r.nextInt(4)+2; chunk1[i] = new BlockMap("res/window/map"+id+".tmx", i*BLOCK_WIDTH); } map = chunk1; chunksLoaded++; The map is then drawn on the screen like this. tmap is a TiledMap object and each block/tile is 16 pixels wide for(int i=0; i<chunkLoad; i++) { map[i].tmap.render((i * BLOCK_WIDTH * 16) + (cameraX), 0); } I can successfully load new chunks, but I can't display them in the correct position, nor the hitboxes. Any suggestions? Thanks.

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  • How do I retain previously drawn graphics?

    - by Cromanium
    I've created a simple program that draws lines from a fixed point to a random point each frame. I wanted to keep each line on the screen. However, it always seems to be cleared each time it draws on the spriteBatch even without GraphicsDevice.Clear(color) being called. What seems to be the problem? protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); DrawLine(spriteBatch); spriteBatch.End(); base.Draw(gameTime); } private void DrawLine(SpriteBatch spriteBatch) { Random r = new Random(); Vector2 a = new Vector2(50, 100); Vector2 b = new Vector2(r.Next(0, 640), r.Next(0,480)); Texture2D filler= new Texture2D(GraphicsDevice, 1, 1, false, SurfaceFormat.Color); filler.SetData(new[] { Color.Black }); float length = Vector2.Distance(a, b); float angle = (float)Math.Atan2(b.Y - a.Y, b.X - a.X); spriteBatch.Draw(filler, a, null, Color.Black, angle, Vector2.Zero, new Vector2(length,10.0f), SpriteEffects.None, 0f); } What am I doing wrong?

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  • Basic Use of ApplyImpulse

    - by nycynik
    I am trying to apply a force to a bunch of b2_dynamicBodys, but it seems to only work for a random number of items and then stops with an error. //create some items to move bodyDef.type = b2Body.b2_dynamicBody; for(var i = 0; i < 5; ++i) { fixDef.shape = new b2PolygonShape; fixDef.shape.SetAsBox(1,1); fixDef.friction = 1; fixDef.restitution = .1; bodyDef.position.x = Math.random() * 10; bodyDef.position.y = Math.random() * 10; bodyDef.linearDamping=1; bodyDef.angularDamping=.8; itemsArray.push(world.CreateBody(bodyDef).CreateFixture(fixDef)); // store for later } then i try to apply a force later with: angle = 20; for (var xIdx=0; xIdx<itemArray.length; xIdx++) { itemsArray[xIdx].GetBody().ApplyImpulse(new b2Vec2(50*Math.cos(angle*Math.PI/180),50*Math.sin(angle*Math.PI/180));); } the error I receive is TypeError: 'undefined' is not an object (evaluating 'c.x') Is there something wrong with saving the items for later use when I am creating them? Does anyone know what is causing this.

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  • Spring <jee:remote-slsb> and JBoss AS7 - No EJB receiver available for handling

    - by Lech Glowiak
    I have got @Remote EJB on JBoss AS 7, available by name java:global/RandomEjb/DefaultRemoteRandom!pl.lechglowiak.ejbTest.RemoteRandom. Standalone client is Spring application that uses <jee:remote-slsb> bean. When trying to use that bean I get java.lang.IllegalStateException: EJBCLIENT000025: No EJB receiver available for handling [appName:, moduleName:RandomEjb, distinctName:] combination for invocation context org.jboss.ejb.client.EJBClientInvocationContext@1a89031. Here is relevant part of applicationContext.xml: <jee:remote-slsb id="remoteRandom" jndi-name="RandomEjb/DefaultRemoteRandom!pl.lechglowiak.ejbTest.RemoteRandom" business-interface="pl.lechglowiak.ejbTest.RemoteRandom" <jee:environment> java.naming.factory.initial=org.jboss.naming.remote.client.InitialContextFactory java.naming.provider.url=remote://localhost:4447 jboss.naming.client.ejb.context=true java.naming.security.principal=testuser java.naming.security.credentials=testpassword </jee:environment> </jee:remote-slsb> <bean id="remoteClient" class="pl.lechglowiak.RemoteClient"> <property name="remote" ref="remoteRandom" /> </bean> RemoteClient.java public class RemoteClient { private RemoteRandom random; public void setRemote(RemoteRandom random){ this.random = random; } public Integer callRandom(){ try { return random.getRandom(100); } catch (Exception e) { e.printStackTrace(); return null; } } } My jboss client jar: org.jboss.as jboss-as-ejb-client-bom 7.1.2.Final pom pl.lechglowiak.ejbTest.RemoteRandom is available for client application classpath. jndi.properties contains exact properties as in <jee:environment> of <jee:remote-slsb>. Such code runs without exception: Context ctx2 = new InitialContext(); RemoteRandom rr = (RemoteRandom) ctx2.lookup("RandomEjb/DefaultRemoteRandom!pl.lechglowiak.ejbTest.RemoteRandom"); System.out.println(rr.getRandom(10000)); But this: ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); RemoteClient client = ctx.getBean("remoteClient", RemoteClient.class); System.out.println(client.callRandom()); ends with exception: java.lang.IllegalStateException: EJBCLIENT000025: No EJB receiver available for handling [appName:, moduleName:RandomEjb, distinctName:] combination for invocation context org.jboss.ejb.client.EJBClientInvocationContext@1a89031. jboss.naming.client.ejb.context=true is set. Do you have any idea what am I setting wrong in <jee:remote-slsb>?

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  • How do you implement position-sensitive zooming inside a JScrollPane?

    - by tucuxi
    I am trying to implement position-sensitive zooming inside a JScrollPane. The JScrollPane contains a component with a customized 'paint' that will draw itself inside whatever space it is allocated - so zooming is as easy as using a MouseWheelListener that resizes the inner component as required. But I also want zooming into (or out of) a point to keep that point as central as possible within the resulting zoomed-in (or -out) view (this is what I refer to as 'position-sensitive' zooming), similar to how zooming works in google maps. I am sure this has been done many times before - does anybody know the "right" way to do it under Java Swing?. Would it be better to play with Graphic2D's transformations instead of using JScrollPanes? Sample code follows: package test; import java.awt.*; import java.awt.event.*; import java.awt.geom.*; import javax.swing.*; public class FPanel extends javax.swing.JPanel { private Dimension preferredSize = new Dimension(400, 400); private Rectangle2D[] rects = new Rectangle2D[50]; public static void main(String[] args) { JFrame jf = new JFrame("test"); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); jf.setSize(400, 400); jf.add(new JScrollPane(new FPanel())); jf.setVisible(true); } public FPanel() { // generate rectangles with pseudo-random coords for (int i=0; i<rects.length; i++) { rects[i] = new Rectangle2D.Double( Math.random()*.8, Math.random()*.8, Math.random()*.2, Math.random()*.2); } // mouse listener to detect scrollwheel events addMouseWheelListener(new MouseWheelListener() { public void mouseWheelMoved(MouseWheelEvent e) { updatePreferredSize(e.getWheelRotation(), e.getPoint()); } }); } private void updatePreferredSize(int n, Point p) { double d = (double) n * 1.08; d = (n > 0) ? 1 / d : -d; int w = (int) (getWidth() * d); int h = (int) (getHeight() * d); preferredSize.setSize(w, h); getParent().doLayout(); // Question: how do I keep 'p' centered in the resulting view? } public Dimension getPreferredSize() { return preferredSize; } private Rectangle2D r = new Rectangle2D.Float(); public void paint(Graphics g) { super.paint(g); g.setColor(Color.red); int w = getWidth(); int h = getHeight(); for (Rectangle2D rect : rects) { r.setRect(rect.getX() * w, rect.getY() * h, rect.getWidth() * w, rect.getHeight() * h); ((Graphics2D)g).draw(r); } } }

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  • Memory efficient int-int dict in Python

    - by Bolo
    Hi, I need a memory efficient int-int dict in Python that would support the following operations in O(log n) time: d[k] = v # replace if present v = d[k] # None or a negative number if not present I need to hold ~250M pairs, so it really has to be tight. Do you happen to know a suitable implementation (Python 2.7)? EDIT Removed impossible requirement and other nonsense. Thanks, Craig and Kylotan! To rephrase. Here's a trivial int-int dictionary with 1M pairs: >>> import random, sys >>> from guppy import hpy >>> h = hpy() >>> h.setrelheap() >>> d = {} >>> for _ in xrange(1000000): ... d[random.randint(0, sys.maxint)] = random.randint(0, sys.maxint) ... >>> h.heap() Partition of a set of 1999530 objects. Total size = 49161112 bytes. Index Count % Size % Cumulative % Kind (class / dict of class) 0 1 0 25165960 51 25165960 51 dict (no owner) 1 1999521 100 23994252 49 49160212 100 int On average, a pair of integers uses 49 bytes. Here's an array of 2M integers: >>> import array, random, sys >>> from guppy import hpy >>> h = hpy() >>> h.setrelheap() >>> a = array.array('i') >>> for _ in xrange(2000000): ... a.append(random.randint(0, sys.maxint)) ... >>> h.heap() Partition of a set of 14 objects. Total size = 8001108 bytes. Index Count % Size % Cumulative % Kind (class / dict of class) 0 1 7 8000028 100 8000028 100 array.array On average, a pair of integers uses 8 bytes. I accept that 8 bytes/pair in a dictionary is rather hard to achieve in general. Rephrased question: is there a memory-efficient implementation of int-int dictionary that uses considerably less than 49 bytes/pair?

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  • SSL Authentication with Certificates: Should the Certificates have a hostname?

    - by sixtyfootersdude
    Summary JBoss allows clients and servers to authenticate using certificates and ssl. One thing that seems strange is that you are not required to give your hostname on the certificate. I think that this means if Server B is in your truststore, Sever B can pretend to be any server that they want. (And likewise: if Client B is in your truststore...) Am I missing something here? Authentication Steps (Summary of Wikipeida Page) Client Server ================================================================================================= 1) Client sends Client Hello ENCRIPTION: None - highest TLS protocol supported - random number - list of cipher suites - compression methods 2) Sever Hello ENCRIPTION: None - highest TLS protocol supported - random number - choosen cipher suite - choosen compression method 3) Certificate Message ENCRIPTION: None - 4) ServerHelloDone ENCRIPTION: None 5) Certificate Message ENCRIPTION: None 6) ClientKeyExchange Message ENCRIPTION: server's public key => only server can read => if sever can read this he must own the certificate - may contain a PreMasterSecerate, public key or nothing (depends on cipher) 7) CertificateVerify Message ENCRIPTION: clients private key - purpose is to prove to the server that client owns the cert 8) BOTH CLIENT AND SERVER: - use random numbers and PreMasterSecret to compute a common secerate 9) Finished message - contains a has and MAC over previous handshakes (to ensure that those unincripted messages did not get broken) 10) Finished message - samething Sever Knows The client has the public key for the sent certificate (step 7) The client's certificate is valid because either: it has been signed by a CA (verisign) it has been self-signed BUT it is in the server's truststore It is not a replay attack because presumably the random number (step 1 or 2) is sent with each message Client Knows The server has the public key for the sent certificate (step 6 with step 8) The server's certificate is valid because either: it has been signed by a CA (verisign) it has been self-signed BUT it is in the client's truststore It is not a replay attack because presumably the random number (step 1 or 2) is sent with each message Potential Problem Suppose the client's truststore has certs in it: Server A Server B (malicous) Server A has hostname www.A.com Server B has hostname www.B.com Suppose: The client tries to connect to Server A but Server B launches a man in the middle attack. Since server B: has a public key for the certificate that will be sent to the client has a "valid certificate" (a cert in the truststore) And since: certificates do not have a hostname feild in them It seems like Server B can pretend to be Server A easily. Is there something that I am missing?

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  • C# A simple Hangman game

    - by Radostin Angelov
    I'm trying to create a simple Hangman game and i have gotten so far, to make it read all words from a text file, but I don't know how to make the code work for every single word. I have another project, working with 3/4 words but with repeating nested if statements. I want to make it as shorter as possible. This is the code i have so far : using System; using System.Linq; class Program { static void Main() { string[] words = System.IO.File.ReadAllLines(@"C:\Users\ADMIN\Desktop\Letters\Letters.txt"); int LengthOfArray = words.Length; Random rnd = new Random(); int random = rnd.Next(1, 3); char[] letters = words[random].ToCharArray(); bool WordIsHidden = true; char hiddenChar = '_'; char GuessedLetter = hiddenChar; var retry = true; while (retry = true) { Console.WriteLine(letters); letters = GuessedLetter.ToString().ToCharArray(); for (int i = 1; i <= LengthOfArray; i++) { Console.Write("{0} ", GuessedLetter); } Console.WriteLine("Enter a letter!"); char letter = char.Parse(Console.ReadLine()); if (words[random].Contains<char>(letter)) { WordIsHidden = false; GuessedLetter = letter; Console.Write(letters); } else { if (WordIsHidden == true) { Console.Write("You guessed wrong!"); } } } } } Also I'm trying to make the game show each letter, the user has guessed on it's corresponding position, but now the letter is one line higher than the rest of the word and it's not in it's right position. Edited: Here is the result : cat ___Enter a letter! a __ aaaEnter a letter! t aa tttEnter a letter! IF anyone have a clue for where does this come from and how can I fix it, any help will be greatly appreciated.

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  • No bean named 'springSecurityFilterChain' is defined

    - by michaeljackson4ever
    When configs are loaded, I get the error SEVERE: Exception starting filter springSecurityFilterChain org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'springSecurityFilterChain' is defined My sec-config: <http use-expressions="true" access-denied-page="/error/casfailed.html" entry-point-ref="headerAuthenticationEntryPoint"> <intercept-url pattern="/" access="permitAll"/> <!-- <intercept-url pattern="/index.html" access="permitAll"/> --> <intercept-url pattern="/index.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/history.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/absence.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/search.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/employees.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/employee.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/contract.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/myforms.html" access="hasAnyRole('HLO','OPISK')"/> <intercept-url pattern="/vacationmsg.html" access="hasAnyRole('ROLE_USER')"/> <intercept-url pattern="/redirect.jsp" filters="none" /> <intercept-url pattern="/error/**" filters="none" /> <intercept-url pattern="/layout/**" filters="none" /> <intercept-url pattern="/js/**" filters="none" /> <intercept-url pattern="/**" access="isAuthenticated()" /> <!-- session-management invalid-session-url="/absence.html"/ --> <!-- logout logout-success-url="/logout.html"/ --> <custom-filter ref="ssoHeaderAuthenticationFilter" before="CAS_FILTER"/> <!-- CAS_FILTER ??? --> </http> <authentication-manager alias="authenticationManager"> <authentication-provider ref="doNothingAuthenticationProvider"/> </authentication-manager> <beans:bean id="doNothingAuthenticationProvider" class="com.nixu.security.sso.web.DoNothingAuthenticationProvider"/> <beans:bean id="ssoHeaderAuthenticationFilter" class="com.nixu.security.sso.web.HeaderAuthenticationFilter"> <beans:property name="groups"> <beans:map> <beans:entry key="cn=lake,ou=confluence,dc=utu,dc=fi" value="ROLE_ADMIN"/> </beans:map> </beans:property> </beans:bean> <beans:bean id="headerAuthenticationEntryPoint" class="com.nixu.security.sso.web.HeaderAuthenticationEntryPoint"/> And web.xml <context-param> <param-name>contextConfigLocation</param-name> <param-value> /WEB-INF/applicationContext.xml /WEB-INF/sec-config.xml /WEB-INF/idm-config.xml /WEB-INF/ldap-config.xml </param-value> </context-param> <display-name>KeyCard</display-name> <context-param> <param-name>webAppRootKey</param-name> <param-value>KeyCardAppRoot</param-value> </context-param> <context-param> <param-name>log4jConfigLocation</param-name> <param-value>/WEB-INF/log4j.properties</param-value> </context-param> <!-- Reads request input using UTF-8 encoding --> <filter> <filter-name>characterEncodingFilter</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter> <filter-name>springSecurityFilterChain</filter-name> <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> </filter> <filter-mapping> <filter-name>characterEncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter-mapping> <filter-name>springSecurityFilterChain</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <listener> <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class> </listener> <listener> <!-- this is for session scoped objects --> <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class> </listener> <listener> <listener-class>org.springframework.security.web.session.HttpSessionEventPublisher</listener-class> </listener> <!-- Handles all requests into the application --> <servlet> <servlet-name>KeyCard</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet> <servlet-name>tiles</servlet-name> <servlet-class>org.apache.tiles.web.startup.TilesServlet</servlet-class> <init-param> <param-name> org.apache.tiles.impl.BasicTilesContainer.DEFINITIONS_CONFIG </param-name> <param-value> /WEB-INF/tilesViewContext.xml </param-value> </init-param> <load-on-startup>2</load-on-startup> </servlet> <servlet-mapping> <servlet-name>KeyCard</servlet-name> <url-pattern>*.html</url-pattern> </servlet-mapping> <session-config> <session-timeout> 120 </session-timeout> </session-config> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <!-- error-page> <exception-type>java.lang.Exception</exception-type> <location>/WEB-INF/error/error.jsp</location> </error-page --> </web-app> What's wrong?

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  • Advantages to Server Scripting languages over Client Side Scripting languages

    There are numerous advantages to server scripting languages over client side scripting languages in regards to creating web sites that are more compelling compared to a standard static site. Server side scripts are executed on a web server during the compilation of data to return to a client. These scripts allow developers to modify the content that is being sent to the user prior to the return of the data to the user as well as store information about the user. In addition, server side scripts allow for a controllable environment in which they can be executed. This cannot be said for client side languages because the developer cannot control the users’ environment compared to a web server. Some users may turn off client scripts, some may be only allow limited access on the system and others may be able to gain full control of the environment.  I have been developing web applications for over 9+ years, and I have used server side languages for most of the applications I have built.  Here is a list of common things I have developed with server side scripts. List of Common Generic Functionality: Send Email FTP Files Security/ Access Control Encryption URL rewriting Data Access Data Creation I/O Access The one important feature server side languages will help me with on my website is Data Access because my component will be backed with a SQL server database. I believe that form validation is one instance where I might see server side and client side scripts used interchangeably because it does not matter how or where the data is validated as long as the data that gets inserted is valid.

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  • [GEEK SCHOOL] Network Security 4: Windows Firewall: Your System’s Best Defense

    - by Ciprian Rusen
    If you have your computer connected to a network, or directly to your Internet connection, then having a firewall is an absolute necessity. In this lesson we will discuss the Windows Firewall – one of the best security features available in Windows! The Windows Firewall made its debut in Windows XP. Prior to that, Windows system needed to rely on third-party solutions or dedicated hardware to protect them from network-based attacks. Over the years, Microsoft has done a great job with it and it is one of the best firewalls you will ever find for Windows operating systems. Seriously, it is so good that some commercial vendors have decided to piggyback on it! Let’s talk about what you will learn in this lesson. First, you will learn about what the Windows Firewall is, what it does, and how it works. Afterward, you will start to get your hands dirty and edit the list of apps, programs, and features that are allowed to communicate through the Windows Firewall depending on the type of network you are connected to. Moving on from there, you will learn how to add new apps or programs to the list of allowed items and how to remove the apps and programs that you want to block. Last but not least, you will learn how to enable or disable the Windows Firewall, for only one type of networks or for all network connections. By the end of this lesson, you should know enough about the Windows Firewall to use and manage it effectively. What is the Windows Firewall? Windows Firewall is an important security application that’s built into Windows. One of its roles is to block unauthorized access to your computer. The second role is to permit authorized data communications to and from your computer. Windows Firewall does these things with the help of rules and exceptions that are applied both to inbound and outbound traffic. They are applied depending on the type of network you are connected to and the location you have set for it in Windows, when connecting to the network. Based on your choice, the Windows Firewall automatically adjusts the rules and exceptions applied to that network. This makes the Windows Firewall a product that’s silent and easy to use. It bothers you only when it doesn’t have any rules and exceptions for what you are trying to do or what the programs running on your computer are trying to do. If you need a refresher on the concept of network locations, we recommend you to read our How-To Geek School class on Windows Networking. Another benefit of the Windows Firewall is that it is so tightly and nicely integrated into Windows and all its networking features, that some commercial vendors decided to piggyback onto it and use it in their security products. For example, products from companies like Trend Micro or F-Secure no longer provide their proprietary firewall modules but use the Windows Firewall instead. Except for a few wording differences, the Windows Firewall works the same in Windows 7 and Windows 8.x. The only notable difference is that in Windows 8.x you will see the word “app” being used instead of “program”. Where to Find the Windows Firewall By default, the Windows Firewall is turned on and you don’t need to do anything special in order for it work. You will see it displaying some prompts once in a while but they show up so rarely that you might forget that is even working. If you want to access it and configure the way it works, go to the Control Panel, then go to “System and Security” and select “Windows Firewall”. Now you will see the Windows Firewall window where you can get a quick glimpse on whether it is turned on and the type of network you are connected to: private networks or public network. For the network type that you are connected to, you will see additional information like: The state of the Windows Firewall How the Windows Firewall deals with incoming connections The active network When the Windows Firewall will notify you You can easily expand the other section and view the default settings that apply when connecting to networks of that type. If you have installed a third-party security application that also includes a firewall module, chances are that the Windows Firewall has been disabled, in order to avoid performance issues and conflicts between the two security products. If that is the case for your computer or device, you won’t be able to view any information in the Windows Firewall window and you won’t be able to configure the way it works. Instead, you will see a warning that says: “These settings are being managed by vendor application – Application Name”. In the screenshot below you can see an example of how this looks. How to Allow Desktop Applications Through the Windows Firewall Windows Firewall has a very comprehensive set of rules and most Windows programs that you install add their own exceptions to the Windows Firewall so that they receive network and Internet access. This means that you will see prompts from the Windows Firewall on occasion, generally when you install programs that do not add their own exceptions to the Windows Firewall’s list. In a Windows Firewall prompt, you are asked to select the network locations to which you allow access for that program: private networks or public networks. By default, Windows Firewall selects the checkbox that’s appropriate for the network you are currently using. You can decide to allow access for both types of network locations or just to one of them. To apply your setting press “Allow access”. If you want to block network access for that program, press “Cancel” and the program will be set as blocked for both network locations. At this step you should note that only administrators can set exceptions in the Windows Firewall. If you are using a standard account without administrator permissions, the programs that do not comply with the Windows Firewall rules and exceptions are automatically blocked, without any prompts being shown. You should note that in Windows 8.x you will never see any Windows Firewall prompts related to apps from the Windows Store. They are automatically given access to the network and the Internet based on the assumption that you are aware of the permissions they require based on the information displayed by the Windows Store. Windows Firewall rules and exceptions are automatically created for each app that you install from the Windows Store. However, you can easily block access to the network and the Internet for any app, using the instructions in the next section. How to Customize the Rules for Allowed Apps Windows Firewall allows any user with an administrator account to change the list of rules and exceptions applied for apps and desktop programs. In order to do this, first start the Windows Firewall. On the column on the left, click or tap “Allow an app or feature through Windows Firewall” (in Windows 8.x) or “Allow a program or feature through Windows Firewall” (in Windows 7). Now you see the list of apps and programs that are allowed to communicate through the Windows Firewall. At this point, the list is grayed out and you can only view which apps, features, and programs have rules that are enabled in the Windows Firewall.

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  • Move Files from a Failing PC with an Ubuntu Live CD

    - by Trevor Bekolay
    You’ve loaded the Ubuntu Live CD to salvage files from a failing system, but where do you store the recovered files? We’ll show you how to store them on external drives, drives on the same PC, a Windows home network, and other locations. We’ve shown you how to recover data like a forensics expert, but you can’t store recovered files back on your failed hard drive! There are lots of ways to transfer the files you access from an Ubuntu Live CD to a place that a stable Windows machine can access them. We’ll go through several methods, starting each section from the Ubuntu desktop – if you don’t yet have an Ubuntu Live CD, follow our guide to creating a bootable USB flash drive, and then our instructions for booting into Ubuntu. If your BIOS doesn’t let you boot using a USB flash drive, don’t worry, we’ve got you covered! Use a Healthy Hard Drive If your computer has more than one hard drive, or your hard drive is healthy and you’re in Ubuntu for non-recovery reasons, then accessing your hard drive is easy as pie, even if the hard drive is formatted for Windows. To access a hard drive, it must first be mounted. To mount a healthy hard drive, you just have to select it from the Places menu at the top-left of the screen. You will have to identify your hard drive by its size. Clicking on the appropriate hard drive mounts it, and opens it in a file browser. You can now move files to this hard drive by drag-and-drop or copy-and-paste, both of which are done the same way they’re done in Windows. Once a hard drive, or other external storage device, is mounted, it will show up in the /media directory. To see a list of currently mounted storage devices, navigate to /media by clicking on File System in a File Browser window, and then double-clicking on the media folder. Right now, our media folder contains links to the hard drive, which Ubuntu has assigned a terribly uninformative label, and the PLoP Boot Manager CD that is currently in the CD-ROM drive. Connect a USB Hard Drive or Flash Drive An external USB hard drive gives you the advantage of portability, and is still large enough to store an entire hard disk dump, if need be. Flash drives are also very quick and easy to connect, though they are limited in how much they can store. When you plug a USB hard drive or flash drive in, Ubuntu should automatically detect it and mount it. It may even open it in a File Browser automatically. Since it’s been mounted, you will also see it show up on the desktop, and in the /media folder. Once it’s been mounted, you can access it and store files on it like you would any other folder in Ubuntu. If, for whatever reason, it doesn’t mount automatically, click on Places in the top-left of your screen and select your USB device. If it does not show up in the Places list, then you may need to format your USB drive. To properly remove the USB drive when you’re done moving files, right click on the desktop icon or the folder in /media and select Safely Remove Drive. If you’re not given that option, then Eject or Unmount will effectively do the same thing. Connect to a Windows PC on your Local Network If you have another PC or a laptop connected through the same router (wired or wireless) then you can transfer files over the network relatively quickly. To do this, we will share one or more folders from the machine booted up with the Ubuntu Live CD over the network, letting our Windows PC grab the files contained in that folder. As an example, we’re going to share a folder on the desktop called ToShare. Right-click on the folder you want to share, and click Sharing Options. A Folder Sharing window will pop up. Check the box labeled Share this folder. A window will pop up about the sharing service. Click the Install service button. Some files will be downloaded, and then installed. When they’re done installing, you’ll be appropriately notified. You will be prompted to restart your session. Don’t worry, this won’t actually log you out, so go ahead and press the Restart session button. The Folder Sharing window returns, with Share this folder now checked. Edit the Share name if you’d like, and add checkmarks in the two checkboxes below the text fields. Click Create Share. Nautilus will ask your permission to add some permissions to the folder you want to share. Allow it to Add the permissions automatically. The folder is now shared, as evidenced by the new arrows above the folder’s icon. At this point, you are done with the Ubuntu machine. Head to your Windows PC, and open up Windows Explorer. Click on Network in the list on the left, and you should see a machine called UBUNTU in the right pane. Note: This example is shown in Windows 7; the same steps should work for Windows XP and Vista, but we have not tested them. Double-click on UBUNTU, and you will see the folder you shared earlier! As well as any other folders you’ve shared from Ubuntu. Double click on the folder you want to access, and from there, you can move the files from the machine booted with Ubuntu to your Windows PC. Upload to an Online Service There are many services online that will allow you to upload files, either temporarily or permanently. As long as you aren’t transferring an entire hard drive, these services should allow you to transfer your important files from the Ubuntu environment to any other machine with Internet access. We recommend compressing the files that you want to move, both to save a little bit of bandwidth, and to save time clicking on files, as uploading a single file will be much less work than a ton of little files. To compress one or more files or folders, select them, and then right-click on one of the members of the group. Click Compress…. Give the compressed file a suitable name, and then select a compression format. We’re using .zip because we can open it anywhere, and the compression rate is acceptable. Click Create and the compressed file will show up in the location selected in the Compress window. Dropbox If you have a Dropbox account, then you can easily upload files from the Ubuntu environment to Dropbox. There is no explicit limit on the size of file that can be uploaded to Dropbox, though a free account begins with a total limit of 2 GB of files in total. Access your account through Firefox, which can be opened by clicking on the Firefox logo to the right of the System menu at the top of the screen. Once into your account, press the Upload button on top of the main file list. Because Flash is not installed in the Live CD environment, you will have to switch to the basic uploader. Click Browse…find your compressed file, and then click Upload file. Depending on the size of the file, this could take some time. However, once the file has been uploaded, it should show up on any computer connected through Dropbox in a matter of minutes. Google Docs Google Docs allows the upload of any type of file – making it an ideal place to upload files that we want to access from another computer. While your total allocation of space varies (mine is around 7.5 GB), there is a per-file maximum of 1 GB. Log into Google Docs, and click on the Upload button at the top left of the page. Click Select files to upload and select your compressed file. For safety’s sake, uncheck the checkbox concerning converting files to Google Docs format, and then click Start upload. Go Online – Through FTP If you have access to an FTP server – perhaps through your web hosting company, or you’ve set up an FTP server on a different machine – you can easily access the FTP server in Ubuntu and transfer files. Just make sure you don’t go over your quota if you have one. You will need to know the address of the FTP server, as well as the login information. Click on Places > Connect to Server… Choose the FTP (with login) Service type, and fill in your information. Adding a bookmark is optional, but recommended. You will be asked for your password. You can choose to remember it until you logout, or indefinitely. You can now browse your FTP server just like any other folder. Drop files into the FTP server and you can retrieve them from any computer with an Internet connection and an FTP client. Conclusion While at first the Ubuntu Live CD environment may seem claustrophobic, it has a wealth of options for connecting to peripheral devices, local computers, and machines on the Internet – and this article has only scratched the surface. Whatever the storage medium, Ubuntu’s got an interface for it! 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