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• Weird GWT issue causing IE threads to skyrocket.

  - by WesleyJohnson

  I'm not sure if this is an issue with GWT, JavaScript, Java, IE or just poor programming, but I'll try to explain. We're implementing web based chat program at work and some of our users have unreliable connections. So we're running into issues where they send out a new message and after x number of milliseconds have passed, the XHR request timesout and the client tries to resend the message again. The issue we ran into was sometimes the message would make it to the server and into the DB, but the XHR request wouldn't make it back to the client so the client was essentially retrying requests that had alread made it to the server. To mitigate this issue, we now send along a count/key with the message. The client says, hey I'm sending msg 50 and it's text is this. If the server already has that message, it just sends back "ok, I got it" and doens't insert into the DB again, eliminating dupes. So the client is free to keep retrying over and over until finally a call comes back from the server saying "Ok, I got it" and then it increments the key and moves on (or we keep them out of the chat if it fails enough). Anyway, so that's the background of what we're doing. The issue is, when we add this code on some versions of IE the threads start increasing gradually everytime it's accessed. On IE8 for Windows7 x64 it doesn't really seem to do it, but on IE8 for Windows Vista x86 it does. So I can't really pinpoint if it's a fluke or my code. Maybe someone had some ideas on a better way to do this. Here is some pseudo code: (the issue seems appear where I increment messageCount? Is this a scope thing, naming conflict, maybe the issue is entirely somewhere else and I'm way off base. public class SFChatClient implements EntryPoint { private List<String> messageQueue; private Integer messageCount = 0; public void onModuleLoad() { messageQueue = new ArrayList<String>(); // setup ui and what not // add a keyhandler to an input box that checks for <ENTER> and calls sendMEssage() } private void sendMessage() { // add message content to the UI for the chat messageQueue.add( //get message from user ); sendQueuedMessages(); } private void sendQueuedMessages() { if( messageQueue.size() > 0 ) { String outgoingMessage = messageQueue.get( 0 ); WebServiceClass.sendMessage( outgoingMessage, messageCount, new WebServiceHandler() { public void onSuccess() { // Delete item 0 from messageQueue messageCount = messageCount + 1; // <--- this seems to cause IE to leak threads. Taking out this code stops the issue??? sendQueuedMessages(); } public void onError() { // Do error handling sendQueuedMessages(); } } ); } } } public class WebServiceClass() { public void sendMessage( String message, Integer messageCount, handler ) { RequestBuilder builder = new RequestBuilder(// create request builder with proper params for the web service url, JSON content type, etc ) { public void onSuccess() { handler.onSuccess() } public void onError() { handler.onError() } } builder.setData( // JSON with message ); bulder.send(); } }

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• How can I clear content without getting the dreaded "stop running this script?" dialog?

  - by Cheeso

  I have a div, that holds a div. like this: <div id='reportHolder' class='column'> <div id='report'> </div> </div> Within the inner div, I add a bunch (7-12) of pairs of a and div elements, like this: <h4><a>Heading1</a></h4> <div> ...content here....</div> The total size of the content, is maybe 200k. Each div just contains a fragment of HTML. Within it, there are numerous <span> elements, containing other html elements, and they nest, to maybe 5-8 levels deep. Nothing really extraordinary, I don't think. After I add all the content, I then create an accordion. like this: $('#report').accordion({collapsible:true, active:false}); This all works fine. The problem is, when I try to clear or remove the report div, it takes a looooooong time, and I get 3 or 4 popups asking "Do you want to stop running this script?" I have tried several ways: option 1: $('#report').accordion('destroy'); $('#report').remove(); $("#reportHolder").html("<div id='report'> </div>"); option 2: $('#report').accordion('destroy'); $('#report').html(''); $("#reportHolder").html("<div id='report'> </div>"); option 3: $('#report').accordion('destroy'); $("#reportHolder").html("<div id='report'> </div>"); after getting a suggestion in the comment, I also tried: option 4: $('#report').accordion('destroy'); $('#report').empty(); $("#reportHolder").html("<div id='report'> </div>"); No matter what, it hangs for a long while. The call to accordion('destroy') seems to not be the source of the delay. It's the erasure of the html content within the report div. This is jQuery 1.3.2. EDIT - fixed code typo. ps: this happens on FF3.5 as well as IE8 . Questions: What is taking so long? How can I remove content more quickly? Addendum I broke into the debugger in FF, during "option 4", and the stacktrace I see is: data() trigger() triggerHandler() add() each() each() add() empty() each() each() (?)() // <<-- this is the call to empty() ResetUi() // <<-- my code onclick I don't understand why add() is in the stack. I am removing content, not adding it. I'm afraid that in the context of the remove (all), jQuery does something naive. Like it grabs the html content, does the text replace to remove one html element, then calls .add() to put back what remains. Is there a way to tell jQuery to NOT propagate events when removing HTML content from the dom?

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• The Collatz Sequence problem

  - by Gandalf StormCrow

  I'm trying to solve this problem, its not a homework question, its just code I'm submitting to uva.onlinejudge.org so I can learn better java trough examples. Here is the problem sample input : 3 100 34 100 75 250 27 2147483647 101 304 101 303 -1 -1 Here is simple output : Case 1: A = 3, limit = 100, number of terms = 8 Case 2: A = 34, limit = 100, number of terms = 14 Case 3: A = 75, limit = 250, number of terms = 3 Case 4: A = 27, limit = 2147483647, number of terms = 112 Case 5: A = 101, limit = 304, number of terms = 26 Case 6: A = 101, limit = 303, number of terms = 1 The thing is this has to execute within 3sec time interval otherwise your question won't be accepted as solution, here is with what I've come up so far, its working as it should just the execution time is not within 3 seconds, here is code : import java.util.Scanner; class Main { public static void main(String[] args) { Scanner stdin = new Scanner(System.in); int start; int limit; int terms; int a = 0; while (stdin.hasNext()) { start = stdin.nextInt(); limit = stdin.nextInt(); if (start > 0) { terms = getLength(start, limit); a++; } else { break; } System.out.println("Case "+a+": A = "+start+", limit = "+limit+", number of terms = "+terms); } } public static int getLength(int x, int y) { int length = 1; while (x != 1) { if (x <= y) { if ( x % 2 == 0) { x = x / 2; length++; }else{ x = x * 3 + 1; length++; } } else { length--; break; } } return length; } } And yes here is how its meant to be solved : An algorithm given by Lothar Collatz produces sequences of integers, and is described as follows: Step 1: Choose an arbitrary positive integer A as the first item in the sequence. Step 2: If A = 1 then stop. Step 3: If A is even, then replace A by A / 2 and go to step 2. Step 4: If A is odd, then replace A by 3 * A + 1 and go to step 2. And yes my question is how can I make it work inside 3 seconds time interval?

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• Multiple constructors in C

  - by meepz

  Hello, I am making a string class in C as a homework and I was wondering how I can make multiple constructors with the same name given the parameter. The commented out area is what I tried to do with results from a few searches but that gives me errors. Pretty much I have some cases where I want to create my new string without any parameter then in other cases create a string with a pointer to character. Here is mystring.h #include <stdio.h> #include <stdlib.h> typedef struct mystring { char * c; int length; int (*sLength)(void * s); char (*charAt)(void * s, int i); int (*compareTo)(void * s1, void * s2); struct mystring * (*concat)(void * s1, void * s2); struct mystring * (*subString)(void * s, int begin, int end); void (*printS)(void * s); } string_t; typedef string_t * String; String newString(char * c); String newString2(); int slength(void * s); char charat(void * S, int i); int compareto(void * s1, void * s2); String concat(void * s1, void * s2); String substring(void * S, int begin, int end); void printstring(void * s); And here is mystring.c #include "mystring.h" String newString(){ } String newString(char * input){ //String newString::newString(char * input) { String s; s = (string_t *) malloc(sizeof(string_t)); s->c = (char *) malloc(sizeof(char) * 20); int i = 0; if (input == NULL){ s->c[0] = '\0'; return s; } while (input[i] != '\0') { s->c[i] = input[i]; i++; } //functions s->sLength = slength; s->charAt = charat; s->compareTo = compareto; s->concat = concat; s->subString = substring; s->printS = printstring; return s; }

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• stdio's remove() not always deleting on time.

  - by Kyte

  For a particular piece of homework, I'm implementing a basic data storage system using sequential files under standard C, which cannot load more than 1 record at a time. So, the basic part is creating a new file where the results of whatever we do with the original records are stored. The previous file's renamed, and a new one under the working name is created. The code's compiled with MinGW 5.1.6 on Windows 7. Problem is, this particular version of the code (I've got nearly-identical versions of this floating around my functions) doesn't always remove the old file, so the rename fails and hence the stored data gets wiped by the fopen(). FILE *archivo, *antiguo; remove("IndiceNecesidades.old"); // This randomly fails to work in time. rename("IndiceNecesidades.dat", "IndiceNecesidades.old"); // So rename() fails. antiguo = fopen("IndiceNecesidades.old", "rb"); // But apparently it still gets deleted, since this turns out null (and I never find the .old in my working folder after the program's done). archivo = fopen("IndiceNecesidades.dat", "wb"); // And here the data gets wiped. Basically, anytime the .old previously exists, there's a chance it's not removed in time for the rename() to take effect successfully. No possible name conflicts both internally and externally. The weird thing's that it's only with this particular file. Identical snippets except with the name changed to Necesidades.dat (which happen in 3 different functions) work perfectly fine. // I'm yet to see this snippet fail. FILE *antiguo, *archivo; remove("Necesidades.old"); rename("Necesidades.dat", "Necesidades.old"); antiguo = fopen("Necesidades.old", "rb"); archivo = fopen("Necesidades.dat", "wb"); Any ideas on why would this happen, and/or how can I ensure the remove() command has taken effect by the time rename() is executed? (I thought of just using a while loop to force call remove() again so long as fopen() returns a non-null pointer, but that sounds like begging for a crash due to overflowing the OS with delete requests or something.)

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• [NEWVERSION]algorithm || method to write prog[UNSOLVED] [closed]

  - by fatai

  I am one of the computer science student. Everyone solve problem with a different or same method, ( but actually I dont know whether they use method or I dont know whether there are such common method to approach problem.) if there are common method, What is it ? If there are different method, which method are you using ? All teacher give us problem which in simple form sometimes, but they donot introduce any approach or method(s) so that we cannot make a decision to choose the method then apply that one to problem , afterward find solution then write code.No help from teacher , push us to find method to solve homework. Ex: my friend is using no method , he says "I start to construct algorithm while I try to write prog." I have found one method when I failed the course, More accurately, my method: When I counter problem in language , I will get more paper and then ; first, input/ output step ; my prog will take this / these there argument(s) and return namely X , ex : in c, input length is not known and at same type , so I must use pointer desired output is in form of package , so use structure second, execution part ; in that step , I am writing all step which are goes to final output ex : in python ; 1.) [ + , [- , 4 , [ * , 1 , 2 ]], 5] 2.) [ + , [- , 4 , 2 ],5 ] 3.) [ + , 2 , 5] 4.) 7 ==> return 7 third, I will write test code ex : in c++ input : append 3 4 5 6 vector_x remove 0 1 desired output vector_x holds : 5 6 now, my other question is ; What is/are other method(s) which have/has been; used to construct class :::: for c++ , python, java used to communicate classes / computers used for solving embedded system problem ::::: for c by other user? Some programmer uses generalized method without considering prog-language(java , perl .. ), what is this method ? Why I wonder , because I learn if you dont costruct algorithm on paper, you may achieve your goal. Like no money no lunch , I can say no algorithm no prog therefore , feel free when you write your own method , a way which is introduced by someone else but you are using and you find it is so efficient

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• Creating a spam list with a web crawler in python

  - by user313623

  Hey guys, I'm not trying to do anything malicious here, I just need to do some homework. I'm a fairly new programmer, I'm using python 3.0, and I having difficulty using recursion for problem-solving. I've been stuck on this question for quite a while. Here's the assignment: Write a recursive method spam(url, n) that takes a url of a web page as input and a non-negative integer n, collects all the email address contained in the web page and adds them to a global dictionary variable spam_dict, and then recursively calls itself on every http hyperlink contained in the web page. You will use a dictionary so only one copy of every email address is save; your dictionary will store (key,value) pairs (email, email). The recursive call should use the parameter n-1 instead of n. If n = 0, you should collect the email addresses but no recursive calls should be made. The parameter n is used to limit the recursion to at most depth n. You will need to use the solutions of the two above problems; you method spam() will call the methods links2() and emails() and possibly other functions as well. Notes: 1. running spam() directly will produce no output on the screen; to find your spam_dict, you will need to read the value of spam_dict, and you will also need to reset it to the empty dictionary before every run of spam. 2. Recall how global variables are used. Usage: spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',0) spam_dict.keys() dict_keys([]) spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',1) spam_dict.keys() dict_keys(['[email protected]', '[email protected]']) So far, I've written a function that traverses web pages and puts all the links in a nice little list, and what I wanted to do was call that functions. And why would I use recursion on a dictionary? And how? I don't understand how n ties into all of this. def links2(url): content = str(urlopen(url).read()) myparser = MyHTMLParser() myparser.feed(content) lst = myparser.get() mergelst = [] for link in lst: mergelst.append(urljoin(lst[0],link)) print(mergelst) Any input (except why spam is bad) would be greatly appreciated. Also, I realize that the above function could probably look better, if you have a way to do it, I'm all ears. However, all I need is the point is for the program to produce the proper output.

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• Complex SQL query with group by and two rows in one

  - by Ricket

  Okay, I need help. I'm usually pretty good at SQL queries but this one baffles me. By the way, this is not a homework assignment, it's a real situation in an Access database and I've written the requirements below myself. Here is my table layout. It's in Access 2007 if that matters; I'm writing the query using SQL. Id (primary key) PersonID (foreign key) EventDate NumberOfCredits SuperCredits (boolean) There are events that people go to. They can earn normal credits, or super credits, or both at one event. The SuperCredits column is true if the row represents a number of super credits earned at the event, or false if it represents normal credits. So for example, if there is an event which person 174 attends, and they earn 3 normal credits and 1 super credit at the event, the following two rows would be added to the table: ID PersonID EventDate NumberOfCredits SuperCredits 1 174 1/1/2010 3 false 2 174 1/1/2010 1 true It is also possible that the person could have done two separate things at the event, so there might be more than two columns for one event, and it might look like this: ID PersonID EventDate NumberOfCredits SuperCredits 1 174 1/1/2010 1 false 2 174 1/1/2010 2 false 3 174 1/1/2010 1 true Now we want to print out a report. Here will be the columns of the report: PersonID LastEventDate NumberOfNormalCredits NumberOfSuperCredits The report will have one row per person. The row will show the latest event that the person attended, and the normal and super credits that the person earned at that event. What I am asking of you is to write, or help me write, the SQL query to SELECT the data and GROUP BY and SUM() and whatnot. Or, let me know if this is for some reason not possible, and how to organize my data to make it possible. This is extremely confusing and I understand if you do not take the time to puzzle through it. I've tried to simplify it as much as possible, but definitely ask any questions if you give it a shot and need clarification. I'll be trying to figure it out but I'm having a real hard time with it, this is grouping beyond my experience...

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• button of MDImenu can't disenable in VS2008

  - by colorlee

  Hi everyone. i had just started to learn VB and VS2008 and im doing some system due to my homework. i made a WELCOME form with a timer, 5s to pass to the next form which called Select. After passed to next form, itll me.visible = false. Theres 3 buttons on the Select form which call Customer, Staff and Exit. As i had just start, the button Customer will pass to a MDI menu call Customer Menu with a menu strip button called Quotation. Same, Select will me.visible = false when done. Then a problem occured, i made a Quotation inside the Customer Menu, such as the mdiparent of Quotation is Customer. I expected that the Quotation button will disenable to press after i pressed that button. But i fail to do that. And the code below: This is the code of MDI menu Customer Menu: Public Class frmCustomer Private Sub ExitToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExitToolStripMenuItem.Click End End Sub Private Sub AboutUsToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AboutUsToolStripMenuItem.Click Dim frm As New AboutMamatai AboutMamatai.ShowDialog() End Sub Private Sub frmCustomer_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load frmQuotation.MdiParent = Me frmQuotation.Show() frmQuotation.Dock = DockStyle.Fill Me.Location = New Point(220, 180) End Sub Private Sub QuotationToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles QuotationToolStripMenuItem.Click frmQuotation.MdiParent = Me frmQuotation.Show() frmQuotation.Dock = DockStyle.Fill End Sub End Class This is the code of the form inside the Customer menu: Public Class frmQuotation Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click frmCustomer.QuotationToolStripMenuItem.Enabled = True Me.Close() End Sub Private Sub frmQuotation_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load frmCustomer.QuotationToolStripMenuItem.Enabled = False End Sub End Class When im tryin to solve this problem, i found that the problem may cause of the me.visible = false of the Select form and Welcome form. Becoz when i set the Customer Menu be the first form to run. The problem is not exist. Is there anyone can help me ? P.S. I guess if the other two forms code is needed so i post them also This is the code of WELCOME form : Public Class frmWELCOME Private Sub frmWELCOME_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Me.Location = New Point(270, 210) Timer1.Enabled = True End Sub Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick Timer1.Enabled = False Dim frm As New frmSelect frm.Show() Me.Visible = False End Sub Private Sub btnSkip_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSkip.Click Timer1.Enabled = False Dim frm As New frmSelect frm.Show() Me.Visible = False End Sub End Class This is the code of Select Form: Public Class frmSelect Private Sub btnCustomer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCustomer.Click Dim frm As New frmCustomer frm.Show() Me.Visible = False End Sub Private Sub btnStaff_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStaff.Click Dim frm As New frmStaff frm.Show() Me.Visible = False End Sub Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click End End Sub Private Sub frmSelect_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Me.Location = New Point(390, 250) End Sub End Class

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• Should I add try/catch around when casting on an attribute of JSP implicit object?

  - by Michael Mao

  Hi all: Basically what I mean is like this: List<String[]> routes = (List<String[]>)application.getAttribute("routes"); For the above code, it tries to get an attribute named "routes" from the JSP implicit object - application. But as everyone knows, after this line of code, routes may very well contains a null - which means this application hasn't got an attribute named "routes". Is this "casting on null" good programming practice in Java or not? Basically I try to avoid exceptions such as java.io.InvalidCastException I reckon things like this are more as "heritage" of Java 1.4 when generic types were not introduced to this language. So I guess everything stored in application attributes as Objects (Similar to traditional ArrayList). And when you do "downcast", there might be invalid casts. What would you do in this case? Update: Just found that although in the implicit object application I did store a List of String arrays, when I do this : List<double[]> routes = (List<double[]>)application.getAttribute("routes"); It doesn't produce any error... And I felt not comfortable already... And even with this code: out.print(routes.get(0)); It does print out something strange : [Ljava.lang.String;@18b352f Am I printing a "pointer to String"? I can finally get an exception like this: out.print(routes.get(0)[1]); with error : java.lang.ClassCastException: [Ljava.lang.String; Because it was me to add the application attribute, I know which type should it be cast to. I feel this is not "good enough", what if I forget the exact type? I know there are still some cases where this sort of thing would happen, such as in JSP/Servlet when you do casting on session attributes. Is there a better way to do this? Before you say:"OMG, why you don't use Servlets???", I should justify my reason as this: - because my uni sucks, its server can only work with Servlets generated by JSP, and I don't really want to learn how to fix issues like that. look at my previous question on this , and this is uni homework, so I've got no other choice, forget all about war, WEB-INF,etc, but "code everything directly into JSP" - because the professors do that too. :)

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• Throwing cats out of windows

  - by AndrewF

  Imagine you're in a tall building with a cat. The cat can survive a fall out of a low story window, but will die if thrown from a high floor. How can you figure out the longest drop that the cat can survive, using the least number of attempts? Obviously, if you only have one cat, then you can only search linearly. First throw the cat from the first floor. If it survives, throw it from the second. Eventually, after being thrown from floor f, the cat will die. You then know that floor f-1 was the maximal safe floor. But what if you have more than one cat? You can now try some sort of logarithmic search. Let's say that the build has 100 floors and you have two identical cats. If you throw the first cat out of the 50th floor and it dies, then you only have to search 50 floors linearly. You can do even better if you choose a lower floor for your first attempt. Let's say that you choose to tackle the problem 20 floors at a time and that the first fatal floor is #50. In that case, your first cat will survive flights from floors 20 and 40 before dying from floor 60. You just have to check floors 41 through 49 individually. That's a total of 12 attempts, which is much better than the 50 you would need had you attempted to use binary elimination. In general, what's the best strategy and it's worst-case complexity for an n-storied building with 2 cats? What about for n floors and m cats? Assume that all cats are equivalent: they will all survive or die from a fall from a given window. Also, every attempt is independent: if a cat survives a fall, it is completely unharmed. This isn't homework, although I may have solved it for school assignment once. It's just a whimsical problem that popped into my head today and I don't remember the solution. Bonus points if anyone knows the name of this problem or of the solution algorithm.

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• Problem with OOP Class Definitions

  - by oben

  Hi, this is Oben from Turkey. I work for my homework in C++ and i have some problems with multiply definitions. My graph class ; class Graph{ private: string name; //Graph name fstream* graphFile; //Graph's file protected: string opBuf; //Operations buffer int containsNode(string); //Query if a node is present Node* nodes; //Nodes in the graph int nofNodes; //Number of nodes in the graph public: static int nOfGraphs; //Number of graphs produced Graph(); //Constructors and destructor Graph(int); Graph(string); Graph(const Graph &); ~Graph(); string getGraphName(); //Get graph name bool addNode(string); //add a node to the graph bool deleteNode(string); //delete a node from the graph bool addEdge(string,string); //add an edge to the graph bool deleteEdge(string,string); //delete an edge from the graph void intersect(const Graph&); //intersect the graph with the <par> void unite(const Graph&); //intersect the graph with the <par> string toString(); //get string representation of the graph void acceptTraverse(BreadthFirst*); void acceptTraverse(DepthFirst *); }; and my traversal class; class Traversal { public: string *visitedNodes; virtual string traverse (const Graph & ); }; class BreadthFirst : public Traversal { public : BreadthFirst(); string traverse(); }; class DepthFirst : public Traversal { public : DepthFirst(); string traverse(); }; My problem is in traversal class , i need to declare Graph class at the same time , in graph class i need traversal class to declare. I have big problems with declerations :) Could you please help me ?

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• Find a base case for a recursive void method

  - by Evan S

  I am doing homework. I would like to build a base case for a recursion where ordering given numbers (list2) in ascending order. Purpose of writing this codes is that when all numbers are in ascending order then should stop calling a method called ascending(list2, list1); and all values in list2 should be shipped to list1. For instance, list2 = 6,5,4,3,2,1 then list2 becomes empty and list1 should be 1,2,3,4,5,6. I am trying to compare result with previous one and if matches then stop. But I can't find the base case to stop it. In addition, Both ascending() and fixedPoint() are void method. Anybody has idea? lol Took me 3 days... When I run my code then 6,5,4,3,2,1 5,6,4,3,2,1 4,5,6,3,2,1 3,4,5,6,2,1 2,3,4,5,6,1 1,2,3,4,5,6 1,2,3,4,5,6 1,2,3,4,5,6 1,2,3,4,5,6 1,2,3,4,5,6 infinite............. public class Flipper { public static void main(String[] args) { Flipper aFlipper = new Flipper(); List<Integer> content = Arrays.asList(6,5,4,3,2,1); ArrayList<Integer> l1 = new ArrayList<Integer>(content); ArrayList<Integer> l2 = new ArrayList<Integer>(); // empty list aFlipper.fixedPoint(l2,l1); System.out.println("fix l1 is "+l1); System.out.println("fix l2 is "+l2); } public void fixedPoint(ArrayList<Integer> list1, ArrayList<Integer> list2) { // data is in list2 ArrayList<Integer> temp1 = new ArrayList<Integer>(); // empty list if (temp1.equals(list2)) { System.out.println("found!!!"); } else { ascending(list2, list1); // data, null temp1 = list1; // store processed value System.out.println("st list1 is "+list1); System.out.println("st list2 is "+list2); } fixedPoint(list2, list1); // null, processed data }

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• ajaxSubmit and Other Code. Can someone help me determine what this code is doing?

  - by Matt Dawdy

  I've inherited some code that I need to debug. It isn't working at present. My task is to get it to work. No other requirements have been given to me. No, this isn't homework, this is a maintenance nightmare job. ASP.Net (framework 3.5), C#, jQury 1.4.2. This project makes heavy use of jQuery and AJAX. There is a drop down on a page that, when an item is chosen, is supposed to add that item (it's a user) to an object in the database. To accomplish this, the previous programmer first, on page load, dynamically loads the entire page through AJAX. To do this, he's got 5 div's, and each one is loaded from a jquery call to a different full page in the website. Somehow, the HTML and BODY and all the other stuff is stripped out and the contents of the div are loaded with the content of the aspx page. Which seems incredibly wrong to me since it relies on the browser to magically strip out html, head, body, form tags and merge with the existing html head body form tags. Also, as the "content" page is returned as a string, the previous programmer has this code running on it before it is appended to the div: function CleanupResponseText(responseText, uniqueName) { responseText = responseText.replace("theForm.submit();", "SubmitSubForm(theForm, $(theForm).parent());"); responseText = responseText.replace(new RegExp("theForm", "g"), uniqueName); responseText = responseText.replace(new RegExp("doPostBack", "g"), "doPostBack" + uniqueName); return responseText; } When the dropdown itself fires it's onchange event, here is the code that gets fired: function SubmitSubForm(form, container) { //ShowLoading(container); $(form).ajaxSubmit( { url: $(form).attr("action"), success: function(responseText) { $(container).html(CleanupResponseText(responseText, form.id)); $("form", container).css("margin-top", "0").css("padding-top", "0"); //HideLoading(container); } } ); } This blows up in IE, with the message that "Microsoft JScript runtime error: Object doesn't support this property or method" -- which, I think, has to be that $(form).ajaxSubmit method doesn't exist. What is this code really trying to do? I am so turned around right now that I think my only option is to scrap everything and start over. But I'd rather not do that unless necessary. Is this code good? Is it working against .Net, and is that why we are having issues?

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• Best approach for using Scanner Objects in Java?

  - by devjeetroy

  Although I'm more of a C++/ASM guy, I have to work with java as a part of my undergrad course at college. Our teacher taught us input using Scanner(System.in), and told us that if multiple functions are were taking user input, it would be advisable that a single Scanner object is passed around so as to reduce chances of the input stream getting screwed up. Now using this approach has gotten me into a situation where I'm trying to use a Scanner.nextLine(), and this statement does not wait for user input. It just moves on to the following statement. I figured there may be some residual cr/lf or other characters in the Scanner that might not have been retrieved are causing the problem. Here is the code. while(lineScanner.hasNext()) { if(isPlaceHolder(temp = lineScanner.next())) { temp = temp.replace("<",""); temp = temp.replace(">", ""); System.out.print("Enter "+aOrA(temp.charAt(0)) +" " +temp + " : "); temp = consoleInput.nextLine(); } outputFileStream.print(temp + " "); } All of the code is inside a function which receives a Scanner object consoleInput. Ok, so what happens when i run it is that when the program enters the if() the first time, It carries out theSystem.out.print, does not wait for user input, and moves on to the second time that it enters the 'if' block. This time, it takes the input and the rest of the program operates normally. What is even more surprising is that when i check the output file created by the program, it is perfect, just as i want to be. Almost as if the first time input using the scanner is correct. I have solved this problem by creating a new system.in Scanner in the function itself, instead of receiving the Scanner object as a parameter. But I am still very curious to know what the hell is happening and why it couldn't be solved using a simple Scanner.reset(). Would it be better to just simply create a Scanner Object for each function? Thanks, Devjeet PS. Although I know how to take input using fileinputstreams and the like, we are not supposed to use it with the homework.

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• circles and triangles problem

  - by Faken

  Hello everyone, I have an interesting problem here I've been trying to solve for the last little while: I have 3 circles on a 2D xy plane, each with the same known radius. I know the coordinates of each of the three centers (they are arbitrary and can be anywhere). What is the largest triangle that can be drawn such that each vertice of the triangle sits on a separate circle, what are the coordinates of those verticies? I've been looking at this problem for hours and asked a bunch of people but so far only one person has been able to suggest a plausible solution (though i have no way of proving it). The solution that we have come up with involves first creating a triangle about the three circle centers. Next we look at each circle individually and calculate the equation of a line that passes through the circle's center and is perpendicular to the opposite edge. We then calculate two intersection points of the circle. This is then done for the next two circles with a result of 6 points. We iterate over the 8 possible 3 point triangles that these 6 points create (the restriction is that each point of the big triangle must be on a separate circle) and find the maximum size. The results look reasonable (at least when drawn out on paper) and it passes the special case of when the centers of the circles all fall on a straight line (gives a known largest triangle). Unfortunate i have no way of proving this is correct or not. I'm wondering if anyone has encountered a problem similar to this and if so, how did you solve it? Note: I understand that this is mostly a math question and not programming, however it is going to be implemented in code and it must be optimized to run very fast and efficient. In fact, I already have the above solution in code and tested to be working, if you would like to take a look, please let me know, i chose not to post it because its all in vector form and pretty much impossible to figure out exactly what is going on (because it's been condensed to be more efficient). Lastly, yes this is for school work, though it is NOT a homework question/assignment/project. It's part of my graduate thesis (abet a very very small part, but still technically is part of it). Thanks for your help.

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• Finding good heuristic for A* search

  - by Martin

  I'm trying to find the optimal solution for a little puzzle game called Twiddle (an applet with the game can be found here). The game has a 3x3 matrix with the number from 1 to 9. The goal is to bring the numbers in the correct order using the minimum amount of moves. In each move you can rotate a 2x2 square either clockwise or counterclockwise. I.e. if you have this state 6 3 9 8 7 5 1 2 4 and you rotate the upper left 2x2 square clockwise you get 8 6 9 7 3 5 1 2 4 I'm using a A* search to find the optimal solution. My f() is simply the number of rotations need. My heuristic function already leads to the optimal solution but I don't think it's the best one you can find. My current heuristic takes each corner, looks at the number at the corner and calculates the manhatten distance to the position this number will have in the solved state (which gives me the number of rotation needed to bring the number to this postion) and sums all these values. I.e. You take the above example: 6 3 9 8 7 5 1 2 4 and this end state 1 2 3 4 5 6 7 8 9 then the heuristic does the following 6 is currently at index 0 and should by at index 5: 3 rotations needed 9 is currently at index 2 and should by at index 8: 2 rotations needed 1 is currently at index 6 and should by at index 0: 2 rotations needed 4 is currently at index 8 and should by at index 3: 3 rotations needed h = 3 + 2 + 2 + 3 = 10 But there is the problem, that you rotate 4 elements at once. So there a rare cases where you can do two (ore more) of theses estimated rotations in one move. This means theses heuristic overestimates the distance to the solution. My current workaround is, to simply excluded one of the corners from the calculation which solves this problem at least for my test-cases. I've done no research if really solves the problem or if this heuristic still overestimates in same edge-cases. So my question is: What is the best heuristic you can come up with? (Disclaimer: This is for a university project, so this is a bit of homework. But I'm free to use any resource if can come up with, so it's okay to ask you guys. Also I will credit Stackoverflow for helping me ;) )

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• A program where user enters a string and the program counts the instances of the letters

  - by user1865183

  This is the first C++ program I have ever written and I'm having trouble understanding the order in which operands must be put in. This is for a class, but it looks like I'm not supposed to use the homework tag. Sorry if I'm doing this wrong. This is my input // Get DNA string string st; cout << "Enter the DNA sequence to be analysed: "; cin >> st; This seems to work ok, but I thought I would include it incase this is what I'm doing wrong. This is what I have so far to check that the input is exclusively C,T,A, or G. It runs through the program and simply prints "Please enter a valid sequnce1, please enter a valid sequence2, ... ect. I'm sure I'm doing something very stupid, I just can't figure it out. // Check that the sequence is all C, T, A, G while (i <= st.size()){ if (st[i] != 'c' && st[i] != 'C' && st[i] != 'g' && st[i] != 'G' && st[i] != 't' && st[i] != 'T' && st[i] != 'a' && st[i] != 'A'); cout << "Please enter a valid sequence" << i++; else if (st[i] == c,C,G,t,T,a,A) i++; The second half of my program is to count the number of Cs and Gs in the sequence for (i < st.size() ; i++ ;); for (loop <= st.size() ; loop++;) if (st[loop] == 'c') { count_c++; } else if (st[loop] == C) { count_c++; } else if (st[loop] == g) { count_g++; } else if (st[loop] == G); { count_g++; } cout << "Number of instances of C = " << count_c; cout << "Number of instances of G = " << count_g; It seems like it's not looping, it will count 1 of one of the letters. How do I make it loop? I can't seem to put in endl; anywhere without getting an error back, although I know I'll need it somewhere. Any help or tips to point me in the right direction would be greatly appreciated - I've been working on this code for two days (this is embarrassing to admit).

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• How do I access the enumerated item with an indexer and assign array string to it for display?

  - by g00p3k

  EDITED: Updated 3/23/09. See rest of post at bottom. I'm still having trouble with the indexer. Anymore help or examples would really help me out. Write a class, MyCourses, that contains an enumeration of all the courses that you are currently taking. This enum should be nested inside of your class MyCourses. Your class should also have an array field that provides a short description (as a String) of each of your courses. Write an indexer that takes one of your enumerated courses as an index and returns the String description of the course. Write a class MyFriends that contains an indexer that provides access to the names of your friends. namespace IT274_Unit4Project { public class MyCourses { // enumeration that contains an enumeration of all the courses that // student is currently enrolled in public enum CourseName {IT274= 0,CS210 = 1} // array field that provides short description for each of classes, // returns string description of the course private String[] courseDescription = {"Intermediate C#: Teaches intermediate elements of C# programming and software design", "Career Development Strategies: Teaches principles for career progression, resume preparation, and overall self anaylsis"}; // indexer that takes one of the enumerated courses as an index // and returns the String description of the course public String this[CourseName index] { get { if (index == 1) return courseDescription[0]; else return courseDescription[1]; } set { if (index == 1) courseDescription[0] = value; else courseDescription[1] = value; } } } }//end public class MyCourses I'm working on this homework project and having trouble understanding the text explaining how to correctly take the accessed value of the enumeration and then apply the string array value to it. Can you please help me understand this? The text we are using is very difficult and poorly written for a beginner to understand, so I'm kind of on my own here. I've got the first parts written, but need some help on the accessing of the enumeration value and assigning, i think i'm close, but don't understand how to properly get and set the values on this. Please do not provide me with direct code answers, unless a MSDN style explanation that is generalized and not specific to my project. ie: public class MyClass { string field1; string field2; //properties public string Value1 get etc... Thanks!

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• makecontext segfault?

  - by cdietschrun

  I am working on a homework assignment that will be due in the next semester. It requires us to implement our own context switching/thread library using the ucontext API. The professor provides code that does it, but before a thread returns, he manually does some work and calls an ISR that finds another thread to use and swapcontexts to it or if none are left, exits. The point of the assignment is to use the uc_link field of the context so that when it hits a return it takes care of the work. I've created a function (type void/void args) that just does the work the functions did before (clean up and then calls ISR). The professor said he wanted this. So all that's left is to do a makecontext somewhere along the way on the context in the uc_link field so that it runs my thread, right? Well, when I do makecontext on seemingly any combination of ucontext_t's and function, I get a segfault and gdb provides no help.. I can skip the makecontext and my program exist 'normally' when it hits a return in the threads I created because (presumably) the uc_link field is not properly setup (which is what I'm trying to do). I also can't find anything on why makecontext would segfault. Can anyone help? stack2.ss_sp = (void *)(malloc(STACKSIZE)); if(stack2.ss_sp == NULL){ printf("thread failed to get stack space\n"); exit(8); } stack2.ss_size = STACKSIZE; stack2.ss_flags = 0; if(getcontext(&main_context) == -1){ perror("getcontext in t_init, rtn_env"); exit(5); } //main_context.uc_stack = t_state[i].mystk; main_context.uc_stack = stack2; main_context.uc_link = 0; makecontext(&main_context, (void (*)(void))thread_rtn, 0); I've also tried just thread_rtn, &thread_rtn and other things. thread_rtn is declared as void thread_rtn(void). later, in each thread. run_env is of type ucontext_t: ... t_state[i].run_env.uc_link = &main_context;

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• Java Error When correct code is put together

  - by Eric

  I have a few string problems that I need to put together for a complete homework assignment. They all work correctly by themselves, but when I put them together in the main function, the last one that finds the smallest word in a string gives an error. Anyone know why? public static void main(String[] args){ Scanner sc = new Scanner(System.in); //Length of Word String word1 = sc.next(); System.out.println(word1.length()); //Evens in one string odds in the other String word2 = sc.next(); StringBuilder even = new StringBuilder(); StringBuilder odd = new StringBuilder(); for(int i = 0; i < word2.length(); i++){ if(i % 2 == 0){ even.append(word2.charAt(i)); } else{ odd.append(word2.charAt(i)); } } System.out.println(even + " " + odd); //Diminishing Suffix String word3 = sc.next(); for(int j = 0; j < word3.length(); j++){ System.out.print(word3.substring(j, word3.length()) + " "); } System.out.printf("\n"); //Letter Replacement String word4 = sc.next(); String word5 = sc.next(); String word6 = sc.next(); String word7 = word4.replace(word5, word6); System.out.println(word7); //How many times x appears in xstring String word8 = sc.next(); String word9 = sc.next(); int index = word8.indexOf(word9); int count = 0; while (index != -1) { count++; word8 = word8.substring(index + 1); index = word8.indexOf(word9); } System.out.println(count); System.out.println(); //Lexicographically smallest word String Sentence = sc.nextLine(); String[] myWords = Sentence.split(" "); int shortestLengths, shortestLocation; shortestLengths=(myWords[1]).length(); shortestLocation=1; for (int i = 1; i <myWords.length; i++) { if ((myWords[i]).length() < shortestLengths) { shortestLengths=(myWords[i]).length(); shortestLocation=i; } } System.out.println(myWords[shortestLocation]); } } Talking about the lexicographically smallest one

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• Try out Windows Phone 7 on your PC today

  - by Matthew Guay

  Anticipation has been building for the new Windows Phone 7 Series ever since Microsoft unveiled it at the Mobile World Congress in February.  Now, thanks to free developer tools, you can get a first-hand experience of the basic Windows Phone 7 Series devices on your PC. Windows Phone 7 Series represents a huge change in the mobile field for Microsoft, bringing the acclaimed Zune HD UI to an innovative phone platform.  Windows Mobile has often been criticized for being behind other Smartphone platforms, but Microsoft seeks to regain the lead with this new upcoming release.  A platform must have developers behind it to be useful, so they have released a full set of free development tools so anyone can make apps for it today.  Or, if you simply want to play with Windows Phone 7, you can use the included emulator to try out the new Metro UI.  Here’s how to do this today on your Vista or 7 computer. Please note: These tools are a Customer Technology Preview release, so only install them if you’re comfortable using pre-release software. Getting Started First, download the Windows Phone Developer Tools CTP (link below), and run the installer.  This will install the Customer Technology Preview (CTP) versions of Visual Studio 2010 Express for Windows Phone, Windows Phone Emulator, Silverlight for Windows Phone, and XNA 4.0 Game Studio on your computer, all of which are required and cannot be installed individually. Accept the license agreement when prompted. Click “Install Now” to install the tools you need.  The only setup customization option is where to save the files, so choose Customize if you need to do so. Setup will now automatically download and install the components you need, and will additionally download either 32 or 64 bit programs depending on your operating system. About halfway thorough the installation, you’ll be prompted to reboot your system.  Once your computer is rebooted, setup will automatically resume without further input.   When setup is finished, click “Run the Product Now” to get started. Running Windows Phone 7 on your PC Now that you’ve got the Windows Phone Developer tools installed, it’s time to get the Windows Phone emulator running.  If you clicked “Run the Product Now” when the setup finished, Visual Studio 2010 Express for Windows Phone should have already started.   If not, simply enter “visual studio” in your start menu search and select “Microsoft Visual Studio 2010 Express for Windows Phone”. Now, to run the Windows Phone 7 emulator, we have to test an application.  So, even if you don’t know how to program, we can open a phone application template, and then test it to run the emulator.  First, click New Project on the left hand side of the front page. Any of the application templates would work for this, but here let’s select “Windows Phone Application”, and then click Ok. Here’s your new application template, which already contains the basic phone application framework.  This is where you’d start if you want to develop a Windows Phone app, but for now we just want to see Windows Phone 7 in action. So, to run the emulator, click Debug in the menu and then select Start Debugging. Your new application will launch inside the Windows Phone 7 Series emulator.  The default template doesn’t give us much, but it does show an example application running in Windows Phone 7.   Exploring Windows Phone 7 Click the Windows button on the emulator to go to the home screen.  Notice the Zune HD-like transition animation.  The emulator only includes Internet Explorer, your test application, and a few settings. Click the arrow on the right to see the available applications in a list. Settings lets you change the theme, regional settings, and the date and time in your emulator.  It also has an applications settings pane, but this currently isn’t populated. The Time settings shows a unique Windows Phone UI. You can return to the home screen by pressing the Windows button.  Here’s the Internet Explorer app running, with the virtual keyboard open to enter an address.  Please note that this emulator can also accept input from your keyboard, so you can enter addresses without clicking on the virtual keyboard. And here’s Google running in Internet Explorer on Windows Phone 7. Windows Phone 7 supports accelerometers, and you can simulate this in the emulator.  Click one of the rotate buttons to rotate the screen in that direction. Here’s our favorite website in Internet Explorer on Windows Phone 7 in landscape mode. All this, running right inside your Windows 7 desktop… Developer tools for Windows Phone 7 Although it may be fun to play with the Windows Phone 7 emulator, developers will be more excited to actually be able to create new and exciting apps for it.  The Windows Phone Developer Tools download includes Visual Studio Express and XNA Game Studio 4.0 which lets you create enticing games and apps for Windows Phones.  All development for Windows Phones will be in C#, Silverlight, and the XNA game framework.  Visual Studio Express for Windows Phone includes templates for these, and additionally has code samples to help you get started with development. Conclusion Many features are still not functional in this preview version, such as the search button and most of the included applications.  However, this still gives you a great way to experience firsthand the future of the Windows Phone platform.  And, for developers, this is your chance to set your mark on the Windows Phone 7 Series even before it is released to the public.  Happy playing and developing! Links Download Windows Phone Developer Tools CTP Windows Phone Developer Site Similar Articles Productive Geek Tips Keep Track of Homework Assignments with SoshikuWeekend Fun: Watch Television On Your PC With TVUPlayerEasily Manage Your Downloads with Download StatusbarCreate a Shortcut or Hotkey to Mute the System Volume in WindowsHow-To Geek on Lifehacker: How to Make Windows Vista Less Annoying TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Convert the Quick Launch Bar into a Super Application Launcher Automate Tasks in Linux with Crontab Discover New Bundled Feeds in Google Reader Play Music in Chrome by Simply Dragging a File 15 Great Illustrations by Chow Hon Lam Easily Sync Files & Folders with Friends & Family

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• I have Oracle SQL Developer Installed, Now What?

  - by thatjeffsmith

  If you’re here because you downloaded a copy of Oracle SQL Developer and now you need help connecting to a database, then you’re in the right place. I’ll show you what you need to get up and going so you can finish your homework, teach yourself Oracle database, or get ready for that job interview. You’ll need about 30 minutes to set everything up…and about 5 years to become proficient with Oracle Oracle Database come with SQL Developer but SQL Developer doesn’t include a database If you install Oracle database, it includes a copy of SQL Developer. If you’re running that copy of SQL Developer, please take a second to upgrade now, as it is WAY out of date. But I’m here to talk to the folks that have downloaded SQL Developer and want to know what to do next. You’ve got it running. You see this ‘Connection’ dialog, and… Where am I connecting to, and who as? You NEED a database Installing SQL Developer does not give you a database. So you’re going to need to install Oracle and create a database, or connect to a database that is already up and running somewhere. Basically you need to know the following: where is this database, what’s it called, and what port is the listener running on? The Default Connection properties in SQL Developer These default settings CAN work, but ONLY if you have installed Oracle Database Express Edition (XE). Localhost is a network alias for 127.0.0.1 which is an IP address that maps to the ‘local’ machine, or the machine you are reading this blog post on. The listener is a service that runs on the server and handles connections for the databases on that machine. You can run a database without a listener and you can run a listener without a database, but you can’t connect to a database on a different server unless both that database and listener are up and running. Each listener ‘listens’ on one or more ports, you need to know the port number for each connection. The default port is 1521, but 1522 is often pretty common. I know all of this sounds very complicated Oracle is a very sophisticated piece of software. It’s not analogous to downloading a mobile phone app and and using it 10 seconds later. It’s not like installing Office/Access either – it requires services, environment setup, kernel tweaks, etc. However. Normally an administrator will setup and install Oracle, create the database, and configure the listener for everyone else to use. They’ll often also setup the connection details for everyone via a ‘TNSNAMES.ORA’ file. This file contains a list of database connection details for folks to browse – kind of like an Oracle database phoneboook. If someone has given you a TNSNAMES.ORA file, or setup your machine to have access to a TNSNAMES file, then you can just switch to the ‘TNS’ connection type, and use the dropdown to select the database you want to connect to. Then you don’t have to worry about the server names, database names, and the port numbers. ORCL – that sounds promising! ORCL is the default SID when creating a new database with the Database Creation Assistant (DBCA). It’s just me, and I need help! No administrator, no database, no nothing. What do you do? You have a few options: Buy a copy of Oracle and download, install, and create a database Download and install XE (FREE!) Download, import, and run our Developer Days Hands-on-Lab (FREE!) If you’re a student (or anyone else) with little to no experience with Oracle, then I recommend the third option. Oracle Technology Network Developer Day: Hands-on Database Application Development Lab The OTN lab runs on a A Virtual Box image which contains: 11gR2 Enterprise Edition copy of Oracle a database and listener running for you to connect to lots of demo data for you to play with SQL Developer installed and ready to connect Some browser based labs you can step through to learn Oracle You download the image, you download and install Virtual Box (also FREE!), then you IMPORT the image you previously downloaded. You then ‘Start’ the image. It will boot a copy of Oracle Enterprise Linux (OEL), start your database, and all that jazz. You can then start up and run SQL Developer inside the image OR you can connect to the database running on the image using the copy of SQL Developer you installed on your host machine. Setup Port Forwarding to Make It Easy to Connect From Your Host When you start the image, it will be assigned an IP address. Depending on what network adapter you select in the image preferences, you may get something that can get out to the internet from your image, something your host machine can see and connect to, or something that kind of just lives out there in a vacuum. You want to avoid the ‘vacuum’ option – unless you’re OK with running SQL Developer inside the Linux image. Open the Virtual Box image properties and go to the Networking options. We’re going to setup port forwarding. This will tell your machine that anything that happens on port 1521 (the default Oracle Listener port), should just go to the image’s port 1521. So I can connect to ‘localhost’ and it will magically get transferred to the image that is running. Oracle Virtual Box Port Forwarding 1521 listener database Now You Just Need a Username and Password The default passwords on this image are all ‘oracle’ – so you can connect as SYS, HR, or whatever – just use ‘oracle’ as the password. The Linux passowrds are all ‘oracle’ too, so you can login as ‘root’ or as ‘oracle’ in the Linux desktop. Connect! Connect as HR to your Oracle database running on the OTN Developer Days Virtual Box image If you’re connecting to someone else’s database, you need to ask the person that manages that environment to create for you an account. Don’t try to ‘guess’ or ‘figure out’ what the username and password is. Introduce yourself, explain your situation, and ask kindly for access. This is your first test – can you connect? I know it’s hard to get started with Oracle. There are however many things we offer to make this easier. You’ll need to do a bit of RTM first though. Once you know what’s required, you will be much more likely to succeed. Of course, if you need help, you know where to find me

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• Laissez les bon temps rouler! (Microsoft BI Conference 2010)

  - by smisner

  "Laissez les bons temps rouler" is a Cajun phrase that I heard frequently when I lived in New Orleans in the mid-1990s. It means "Let the good times roll!" and encapsulates a feeling of happy expectation. As I met with many of my peers and new acquaintances at the Microsoft BI Conference last week, this phrase kept running through my mind as people spoke about their plans in their respective businesses, the benefits and opportunities that the recent releases in the BI stack are providing, and their expectations about the future of the BI stack. Notwithstanding some jabs here and there to point out the platform is neither perfect now nor will be anytime soon (along with admissions that the competitors are also not perfect), and notwithstanding several missteps by the event organizers (which I don't care to enumerate), the overarching mood at the conference was positive. It was a refreshing change from the doom and gloom hovering over several conferences that I attended in 2009. Although many people expect economic hardships to continue over the coming year or so, everyone I know in the BI field is busier than ever and expects to stay busy for quite a while. Self-Service BI Self-service was definitely a theme of the BI conference. In the keynote, Ted Kummert opened with a look back to a fairy tale vision of self-service BI that he told in 2008. At that time, the fairy tale future was a time when "every end user was able to use BI technologies within their job in order to move forward more effectively" and transitioned to the present time in which SQL Server 2008 R2, Office 2010, and SharePoint 2010 are available to deliver managed self-service BI. This set of technologies is presumably poised to address the needs of the 80% of users that Kummert said do not use BI today. He proceeded to outline a series of activities that users ought to be able to do themselves--from simple changes to a report like formatting or an addtional data visualization to integration of an additional data source. The keynote then continued with a series of demonstrations of both current and future technology in support of self-service BI. Some highlights that interested me: PowerPivot, of course, is the flagship product for self-service BI in the Microsoft BI stack. In the TechEd keynote, which was open to the BI conference attendees, Amir Netz (twitter) impressed the audience by demonstrating interactivity with a workbook containing 100 million rows. He upped the ante at the BI keynote with his demonstration of a future-state PowerPivot workbook containing over 2 billion records. It's important to note that this volume of data is being processed by a server engine, and not in the PowerPivot client engine. (Yes, I think it's impressive, but none of my clients are typically wrangling with 2 billion records at a time. Maybe they're thinking too small. This ability to work quickly with large data sets has greater implications for BI solutions than for self-service BI, in my opinion.) Amir also demonstrated KPIs for the future PowerPivot, which appeared to be easier to implement than in any other Microsoft product that supports KPIs, apart from simple KPIs in SharePoint. (My initial reaction is that we have one more place to build KPIs. Great. It's confusing enough. I haven't seen how well those KPIs integrate with other BI tools, which will be important for adoption.) One more PowerPivot feature that Amir showed was a graphical display of the lineage for calculations. (This is hugely practical, especially if you build up calculations incrementally. You can more easily follow the logic from calculation to calculation. Furthermore, if you need to make a change to one calculation, you can assess the impact on other calculations.) Another product demonstration will be available within the next 30 days--Pivot for Reporting Services. If you haven't seen this technology yet, check it out at www.getpivot.com. (It definitely has a wow factor, but I'm skeptical about its practicality. However, I'm looking forward to trying it out with data that I understand.) Michael Tejedor (twitter) demonstrated a feature that I think is really interesting and not emphasized nearly enough--overshadowed by PowerPivot, no doubt. That feature is the Microsoft Business Intelligence Indexing Connector, which enables search of the content of Excel workbooks and Reporting Services reports. (This capability existed in MOSS 2007, but was more cumbersome to implement. The search results in SharePoint 2010 are not only cooler, but more useful by describing whether the content is found in a table or a chart, for example.) This may yet be the dawning of the age of self-service BI - a phrase I've heard repeated from time to time over the last decade - but I think BI professionals are likely to stay busy for a long while, and need not start looking for a new line of work. Kummert repeatedly referenced strategic BI solutions in contrast to self-service BI to emphasize that self-service BI is not a replacement for the services that BI professionals provide. After all, self-service BI does not appear magically on user desktops (or whatever device they want to use). A supporting infrastructure is necessary, and grows in complexity in proportion to the need to simplify BI for users. It's one thing to hear the party line touted by Microsoft employees at the BI keynote, but it's another to hear from the people who are responsible for implementing and supporting it within an organization. Rob Collie (blog | twitter), Kasper de Jonge (blog | twitter), Vidas Matelis (site | twitter), and I were invited to join Andrew Brust (blog | twitter) as he led a Birds of a Feather session at TechEd entitled "PowerPivot: Is It the BI Deal-Changer for Developers and IT Pros?" I would single out the prevailing concern in this session as the issue of control. On one side of this issue were those who were concerned that they would lose control once PowerPivot is implemented. On the other side were those who believed that data should be freely accessible to users in PowerPivot, and even acknowledgment that users would get the data they want even if it meant they would have to manually enter into a workbook to have it ready for analysis. For another viewpoint on how PowerPivot played out at the conference, see Rob Collie's observations. Collaborative BI I have been intrigued by the notion of collaborative BI for a very long time. Before I discovered BI, I was a Lotus Notes developer and later a manager of developers, working in a software company that enabled collaboration in the legal industry. Not only did I help create collaborative systems for our clients, I created a complete project management from the ground up to collaboratively manage our custom development work. In that case, collaboration involved my team, my client contacts, and me. I was also able to produce my own BI from that system as well, but didn't know that's what I was doing at the time. Only in recent years has SharePoint begun to catch up with the capabilities that I had with Lotus Notes more than a decade ago. Eventually, I had the opportunity at that job to formally investigate BI as another product offering for our software, and the rest - as they say - is history. I built my first data warehouse with Scott Cameron (who has also ventured into the authoring world by writing Analysis Services 2008 Step by Step and was at the BI Conference last week where I got to reminisce with him for a bit) and that began a career that I never imagined at the time. Fast forward to 2010, and I'm still lauding the virtues of collaborative BI, if only the tools will catch up to my vision! Thus, I was anxious to see what Donald Farmer (blog | twitter) and Rita Sallam of Gartner had to say on the subject in their session "Collaborative Decision Making." As I suspected, the tools aren't quite there yet, but the vendors are moving in the right direction. One thing I liked about this session was a non-Microsoft perspective of the state of the industry with regard to collaborative BI. In addition, this session included a better demonstration of SharePoint collaborative BI capabilities than appeared in the BI keynote. Check out the video in the link to the session to see the demonstration. One of the use cases that was demonstrated was linking from information to a person, because, as Donald put it, "People don't trust data, they trust people." The Microsoft BI Stack in General A question I hear all the time from students when I'm teaching is how to know what tools to use when there is overlap between products in the BI stack. I've never taken the time to codify my thoughts on the subject, but saw that my friend Dan Bulos provided good insight on this topic from a variety of perspectives in his session, "So Many BI Tools, So Little Time." I thought one of his best points was that ideally you should be able to design in your tool of choice, and then deploy to your tool of choice. Unfortunately, the ideal is yet to become real across the platform. The closest we come is with the RDL in Reporting Services which can be produced from two different tools (Report Builder or Business Intelligence Development Studio's Report Designer), manually, or by a third-party or custom application. I have touted the idea for years (and publicly said so about 5 years ago) that eventually more products would be RDL producers or consumers, but we aren't there yet. Maybe in another 5 years. Another interesting session that covered the BI stack against a backdrop of competitive products was delivered by Andrew Brust. Andrew did a marvelous job of consolidating a lot of information in a way that clearly communicated how various vendors' offerings compared to the Microsoft BI stack. He also made a particularly compelling argument about how the existence of an ecosystem around the Microsoft BI stack provided innovation and opportunities lacking for other vendors. Check out his presentation, "How Does the Microsoft BI Stack...Stack Up?" Expo Hall I had planned to spend more time in the Expo Hall to see who was doing new things with the BI stack, but didn't manage to get very far. Each time I set out on an exploratory mission, I got caught up in some fascinating conversations with one or more of my peers. I find interacting with people that I meet at conferences just as important as attending sessions to learn something new. There were a couple of items that really caught me eye, however, that I'll share here. Pragmatic Works. Whether you develop SSIS packages, build SSAS cubes, or author SSRS reports (or all of the above), you really must take a look at BI Documenter. Brian Knight (twitter) walked me through the key features, and I must say I was impressed. Once you've seen what this product can do, you won't want to document your BI projects any other way. You can download a free single-user database edition, or choose from more feature-rich standard or professional editions. Microsoft Press ebooks. I also stopped by the O'Reilly Media booth to meet some folks that one of my acquisitions editors at Microsoft Press recommended. In case you haven't heard, Microsoft Press has partnered with O'Reilly Media for distribution and publishing. Apart from my interest in learning more about O'Reilly Media as an author, an advertisement in their booth caught me eye which I think is a really great move. When you buy Microsoft Press ebooks through the O'Reilly web site, you can receive it in any (or all) of the following formats where possible: PDF, epub, .mobi for Kindle and .apk for Android. You also have lifetime DRM-free access to the ebooks. As someone who is an avid collector of books, I fnd myself running out of room for storage. In addition, I travel a lot, and it's hard to lug my reference library with me. Today's e-reader options make the move to digital books a more viable way to grow my library. Having a variety of formats means I am not limited to a single device, and lifetime access means I don't have to worry about keeping track of where I've stored my files. Because the e-books are DRM-free, I can copy and paste when I'm compiling notes, and I can print pages when necessary. That's a winning combination in my mind! Overall, I was pleased with the BI conference. There were many more sessions that I couldn't attend, either because the room was full when I got there or there were multiple sessions running concurrently that I wanted to see. Fortunately, many of the sessions are accessible for viewing online at http://www.msteched.com/2010/NorthAmerica along with the TechEd sessions. You can spot the BI sessions by the yellow skyline on the title slide of the presentation as shown below. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Stored Procedures with SSRS? Hmm… not so much

  - by Rob Farley

  Little Bobby Tables’ mother says you should always sanitise your data input. Except that I think she’s wrong. The SQL Injection aspect is for another post, where I’ll show you why I think SQL Injection is the same kind of attack as many other attacks, such as the old buffer overflow, but here I want to have a bit of a whinge about the way that some people sanitise data input, and even have a whinge about people who insist on using stored procedures for SSRS reports. Let me say that again, in case you missed it the first time: I want to have a whinge about people who insist on using stored procedures for SSRS reports. Let’s look at the data input sanitisation aspect – except that I’m going to call it ‘parameter validation’. I’m talking about code that looks like this: create procedure dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) as begin     /* First check that @eomdate is a valid date */     if isdate(@eomdate) != 1     begin         select 'Please enter a valid date' as ErrorMessage;         return;     end     /* Then check that time has passed since @eomdate */     if datediff(day,@eomdate,sysdatetime()) < 5     begin         select 'Sorry - EOM is not complete yet' as ErrorMessage;         return;     end         /* If those checks have succeeded, return the data */     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales     from Sales.SalesOrderHeader     where OrderDate >= dateadd(month,-1,@eomdate)         and OrderDate < @eomdate     group by SalesPersonID     order by SalesPersonID; end Notice that the code checks that a date has been entered. Seriously??!! This must only be to check for NULL values being passed in, because anything else would have to be a valid datetime to avoid an error. The other check is maybe fair enough, but I still don’t like it. The two problems I have with this stored procedure are the result sets and the small fact that the stored procedure even exists in the first place. But let’s consider the first one of these problems for starters. I’ll get to the second one in a moment. If you read Jes Borland (@grrl_geek)’s recent post about returning multiple result sets in Reporting Services, you’ll be aware that Reporting Services doesn’t support multiple results sets from a single query. And when it says ‘single query’, it includes ‘stored procedure call’. It’ll only handle the first result set that comes back. But that’s okay – we have RETURN statements, so our stored procedure will only ever return a single result set.  Sometimes that result set might contain a single field called ErrorMessage, but it’s still only one result set. Except that it’s not okay, because Reporting Services needs to know what fields to expect. Your report needs to hook into your fields, so SSRS needs to have a way to get that information. For stored procs, it uses an option called FMTONLY. When Reporting Services tries to figure out what fields are going to be returned by a query (or stored procedure call), it doesn’t want to have to run the whole thing. That could take ages. (Maybe it’s seen some of the stored procedures I’ve had to deal with over the years!) So it turns on FMTONLY before it makes the call (and turns it off again afterwards). FMTONLY is designed to be able to figure out the shape of the output, without actually running the contents. It’s very useful, you might think. set fmtonly on exec dbo.GetMonthSummaryPerSalesPerson '20030401'; set fmtonly off Without the FMTONLY lines, this stored procedure returns a result set that has three columns and fourteen rows. But with FMTONLY turned on, those rows don’t come back. But what I do get back hurts Reporting Services. It doesn’t run the stored procedure at all. It just looks for anything that could be returned and pushes out a result set in that shape. Despite the fact that I’ve made sure that the logic will only ever return a single result set, the FMTONLY option kills me by returning three of them. It would have been much better to push these checks down into the query itself. alter procedure dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) as begin     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales     from Sales.SalesOrderHeader     where     /* Make sure that @eomdate is valid */         isdate(@eomdate) = 1     /* And that it's sufficiently past */     and datediff(day,@eomdate,sysdatetime()) >= 5     /* And now use it in the filter as appropriate */     and OrderDate >= dateadd(month,-1,@eomdate)     and OrderDate < @eomdate     group by SalesPersonID     order by SalesPersonID; end Now if we run it with FMTONLY turned on, we get the single result set back. But let’s consider the execution plan when we pass in an invalid date. First let’s look at one that returns data. I’ve got a semi-useful index in place on OrderDate, which includes the SalesPersonID and TotalDue fields. It does the job, despite a hefty Sort operation. …compared to one that uses a future date: You might notice that the estimated costs are similar – the Index Seek is still 28%, the Sort is still 71%. But the size of that arrow coming out of the Index Seek is a whole bunch smaller. The coolest thing here is what’s going on with that Index Seek. Let’s look at some of the properties of it. Glance down it with me… Estimated CPU cost of 0.0005728, 387 estimated rows, estimated subtree cost of 0.0044385, ForceSeek false, Number of Executions 0. That’s right – it doesn’t run. So much for reading plans right-to-left... The key is the Filter on the left of it. It has a Startup Expression Predicate in it, which means that it doesn’t call anything further down the plan (to the right) if the predicate evaluates to false. Using this method, we can make sure that our stored procedure contains a single query, and therefore avoid any problems with multiple result sets. If we wanted, we could always use UNION ALL to make sure that we can return an appropriate error message. alter procedure dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) as begin     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales, /*Placeholder: */ '' as ErrorMessage     from Sales.SalesOrderHeader     where     /* Make sure that @eomdate is valid */         isdate(@eomdate) = 1     /* And that it's sufficiently past */     and datediff(day,@eomdate,sysdatetime()) >= 5     /* And now use it in the filter as appropriate */     and OrderDate >= dateadd(month,-1,@eomdate)     and OrderDate < @eomdate     group by SalesPersonID     /* Now include the error messages */     union all     select 0, 0, 0, 'Please enter a valid date' as ErrorMessage     where isdate(@eomdate) != 1     union all     select 0, 0, 0, 'Sorry - EOM is not complete yet' as ErrorMessage     where datediff(day,@eomdate,sysdatetime()) < 5     order by SalesPersonID; end But still I don’t like it, because it’s now a stored procedure with a single query. And I don’t like stored procedures that should be functions. That’s right – I think this should be a function, and SSRS should call the function. And I apologise to those of you who are now planning a bonfire for me. Guy Fawkes’ night has already passed this year, so I think you miss out. (And I’m not going to remind you about when the PASS Summit is in 2012.) create function dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) returns table as return (     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales, '' as ErrorMessage     from Sales.SalesOrderHeader     where     /* Make sure that @eomdate is valid */         isdate(@eomdate) = 1     /* And that it's sufficiently past */     and datediff(day,@eomdate,sysdatetime()) >= 5     /* And now use it in the filter as appropriate */     and OrderDate >= dateadd(month,-1,@eomdate)     and OrderDate < @eomdate     group by SalesPersonID     union all     select 0, 0, 0, 'Please enter a valid date' as ErrorMessage     where isdate(@eomdate) != 1     union all     select 0, 0, 0, 'Sorry - EOM is not complete yet' as ErrorMessage     where datediff(day,@eomdate,sysdatetime()) < 5 ); We’ve had to lose the ORDER BY – but that’s fine, as that’s a client thing anyway. We can have our reports leverage this stored query still, but we’re recognising that it’s a query, not a procedure. A procedure is designed to DO stuff, not just return data. We even get entries in sys.columns that confirm what the shape of the result set actually is, which makes sense, because a table-valued function is the right mechanism to return data. And we get so much more flexibility with this. If you haven’t seen the simplification stuff that I’ve preached on before, jump over to http://bit.ly/SimpleRob and watch the video of when I broke a microphone and nearly fell off the stage in Wales. You’ll see the impact of being able to have a simplifiable query. You can also read the procedural functions post I wrote recently, if you didn’t follow the link from a few paragraphs ago. So if we want the list of SalesPeople that made any kind of sales in a given month, we can do something like: select SalesPersonID from dbo.GetMonthSummaryPerSalesPerson(@eomonth) order by SalesPersonID; This doesn’t need to look up the TotalDue field, which makes a simpler plan. select * from dbo.GetMonthSummaryPerSalesPerson(@eomonth) where SalesPersonID is not null order by SalesPersonID; This one can avoid having to do the work on the rows that don’t have a SalesPersonID value, pushing the predicate into the Index Seek rather than filtering the results that come back to the report. If we had joins involved, we might see some of those being simplified out. We also get the ability to include query hints in individual reports. We shift from having a single-use stored procedure to having a reusable stored query – and isn’t that one of the main points of modularisation? Stored procedures in Reporting Services are just a bit limited for my liking. They’re useful in plenty of ways, but if you insist on using stored procedures all the time rather that queries that use functions – that’s rubbish. @rob_farley

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