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  • SQL Server architecture guidance

    - by Liam
    Hi, We are designing a new version of our existing product on a new schema. Its an internal web application with possibly 100 concurrent users (max)This will run on a SQL Server 2008 database. On of the discussion items recently is whether we should have a single database of split the database for performance reasons across 2 separate databases. The database could grow anywhere from 50-100GB over 5 years. We are Developers and not DBAs so it would be nice to get some general guidance. [I know the answer is not simple as it depends on the schema, archiving policy, amount of data etc. ] Option 1 Single Main Database [This is my preferred option]. The plan would be to have all the tables in a single database and possibly to use file groups and partitioning to separate the data if required across multiple disks. [Use schema if appropriate]. This should deal with the performance concerns One of the comments wrt this was that the a single server instance would still be processing this data so there would still be a processing bottle neck. For reporting we could have a separate reporting DB but this is still being discussed. Option 2 Split the database into 2 separate databases DB1 - Customers, Accounts, Customer resources etc DB2 - This would contain the bulk of the data [i.e. Vehicle tracking data, financial transaction tables etc]. These tables would typically contain a lot of data. [It could reside on a separate server if required] This plan would involve keeping the main data in a smaller database [DB1] and retaining the [mainly] read only transaction type data in a separate DB [DB2]. The UI would mainly read from DB1 and thus be more responsive. [I'm aware that this option makes it harder for Referential Integrity to be enforced.] Points for consideration As we are at the design stage we can at least make proper use of indexes to deal performance issues so thats why option 1 to me is attractive and its more of a standard approach. For both options we are considering implementing an archiving database. Apologies for the long Question. In summary the question is 1 DB or 2? Thanks in advance, Liam

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  • Please help fix and optimize this query

    - by user607217
    I am working on a system to find potential duplicates in our customers table (SQL 2005). I am using the built-in SOUNDEX value that our software computes when customers are added/updated, but I also implemented the double metaphone algorithm for better matching. This is the most-nested query I have created, and I can't help but think there is a better way to do it and I'd like to learn. In the inner-most query I am joining the customer table to the metaphone table I created, then finding customers that have identical pKey (primary phonetic key). I take that, union that with customers that have matching soundex values, and then proceed to score those matches with various text similarity functions. This is currently working, but I would also like to add a union of customers whose aKey (alternate phonetic key) match. This would be identical to "QUERY A" except to substitute on (c1Akey = c2Akey) for the join. However, when I attempt to include that, I get errors when I try to execute my query. Here is the code: --Create aggregate ranking select c1Name, c2Name, nDiff, c1Addr, c2Addr, aDiff, c1SSN, c2SSN, sDiff, c1DOB, c2DOB, dDiff, nDiff+aDiff+dDiff+sDiff as Score ,(sDiff+dDiff)*1.5 + (nDiff+dDiff)*1.5 + (nDiff+sDiff)*1.5 + aDiff *.5 + nDiff *.5 as [Rank] FROM ( --Create match scores for different fields SELECT c1Name, c2Name, c1Addr, c2Addr, c1SSN, c2SSN, c1LTD, c2LTD, c1DOB, c2DOB, dbo.Jaro(c1name, c2name) AS nDiff, dbo.JaroWinkler(c1addr, c2addr) AS aDiff, CASE WHEN c1dob = '1901-01-01' OR c2dob = '1901-01-01' OR c1dob = '1800-01-01' OR c2dob = '1800-01-01' THEN .5 ELSE dbo.SmithWaterman(c1dob, c2dob) END AS dDiff, CASE WHEN c1ssn = '000-00-0000' OR c2ssn = '000-00-0000' THEN .5 ELSE dbo.Jaro(c1ssn, c2ssn) END AS sDiff FROM -- Generate list of possible matches based on multiple phonetic matching fields ( select * from -- List of similar names from pKey field of ##Metaphone table --QUERY A BEGIN (select customers.custno as c1Custno, name as c1Name, haddr as c1Addr, ssn as c1SSN, lasttripdate as c1LTD, dob as c1DOB, soundex as c1Soundex, pkey as c1Pkey, akey as c1Akey from Customers WITH (nolock) join ##Metaphone on customers.custno = ##Metaphone.custno) as c1 JOIN (select customers.custno as c2Custno, name as c2Name, haddr as c2Addr, ssn as c2SSN, lasttripdate as c2LTD, dob as c2DOB, soundex as c2Soundex, pkey as c2Pkey, akey as c2Akey from Customers with (nolock) join ##Metaphone on customers.custno = ##Metaphone.custno) as c2 on (c1Pkey = c2Pkey) and (c1Custno < c2Custno) WHERE (c1Name <> 'PARENT, GUARDIAN') and c1soundex != c2soundex --QUERY A END union --List of similar names from pregenerated SOUNDEX field (select t1.custno, t1.name, t1.haddr, t1.ssn, t1.lasttripdate, t1.dob, t1.[soundex], 0, 0, t2.custno, t2.name, t2.haddr, t2.ssn, t2.lasttripdate, t2.dob, t2.[soundex], 0, 0 from Customers t1 WITH (nolock) join customers t2 with (nolock) on t1.[soundex] = t2.[soundex] and t1.custno < t2.custno where (t1.name <> 'PARENT, GUARDIAN')) ) as a ) as b where (sDiff+dDiff)*1.5 + (nDiff+dDiff)*1.5 + (nDiff+sDiff)*1.5 + aDiff *.5 + nDiff *.5 >= 7.5 order by [rank] desc, score desc Previously, I was using joins such as on c1.pkey = c2.pkey or c1.akey = c2.akey or c1.soundex = c2.soundex but the performance was horrendous, and using unions seems to be working a lot better. Out of 103K customers, tt is currently generating a list of 8.5M potential matches (based on the phonetic codes) in 2.25 minutes, and then taking another 2 to score, rank and filter those down to about 3000. So I am happy with the performance, I just can't help but think there is a better way to structure this, and I need help adding the extra union condition. Thanks!

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  • (mySQL) Unable to query 2 tables properly for data

    - by Devner
    I have 2 tables. One is 'page_links' and the other is 'rpp'. Table page_links is the superset of table rpp. The following is the schema of my tables: -- Table structure for table `page_links` -- CREATE TABLE IF NOT EXISTS `page_links` ( `page` varchar(255) NOT NULL, `page_link` varchar(100) NOT NULL, `heading_id` tinyint(3) unsigned NOT NULL, PRIMARY KEY (`page`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -- Dumping data for table `page_links` -- INSERT INTO `page_links` (`page`, `page_link`, `heading_id`) VALUES ('a1.php', 'A1', 8), ('b1.php', 'B1', 8), ('c1.php', 'C1', 5), ('d1.php', 'D1', 5), ('e1.php', 'E1', 8), ('f1.php', 'F1', 8), ('g1.php', 'G1', 8), ('h1.php', 'H1', 1), ('i1.php', 'I1', 1), ('j1.php', 'J1', 8), ('k1.php', 'K1', 8), ('l1.php', 'L1', 8), ('m1.php', 'M1', 8), ('n1.php', 'N1', 8), ('o1.php', 'O1', 8), ('p1.php', 'P1', 4), ('q1.php', 'Q1', 5), ('r1.php', 'R1', 4); -- Table structure for table `rpp` -- CREATE TABLE IF NOT EXISTS `rpp` ( `role_id` tinyint(3) unsigned NOT NULL, `page` varchar(255) NOT NULL, `is_allowed` tinyint(1) NOT NULL, PRIMARY KEY (`role_id`,`page`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -- Dumping data for table `rpp` -- INSERT INTO `rpp` (`role_id`, `page`, `is_allowed`) VALUES (3, 'a1.php', 1), (3, 'b1.php', 1), (3, 'c1.php', 1), (3, 'd1.php', 1), (3, 'e1.php', 1), (3, 'f1.php', 1), (3, 'h1.php', 1), (3, 'i1.php', 1), (3, 'l1.php', 1), (3, 'm1.php', 1), (3, 'n1.php', 1), (4, 'a1.php', 1), (4, 'b1.php', 1), (4, 'q1.php', 1), (5, 'r1.php', 1); WHAT I AM TRYING TO DO: I am trying to query both the above tables (in a single query) in such a way that all the pages from page_links are displayed along with the is_allowed value from rpp for a particular role. For example, I want to get the is_allowed value of all the pages from rpp for role_id = 3 and at the same time, list all the available pages from page_links. A clear example of my expected result would be: page is_allowed role_id ---------------------------------------- a1.php 1 3 b1.php 1 3 c1.php 1 3 d1.php 1 3 e1.php 1 3 f1.php 1 3 g1.php NULL NULL h1.php 1 3 i1.php 1 3 j1.php NULL NULL k1.php NULL NULL l1.php 1 3 m1.php 1 3 n1.php 1 3 o1.php NULL NULL p1.php NULL NULL q1.php NULL NULL r1.php NULL NULL One more example of my desired result could be achieved by doing a LEFT JOIN rpp ON page_links.page = rpp.page but we need to omit using role_id = 3 (or any value) to be able to get that. But I do want to specify the role_id as well and get the results. I need the query to be able to get this result. I would appreciate any replies that could help me with this. If you can suggest me any changes as well to the table(s) design to be able to achieve the desired result, that's good as well. Thanks in advance.

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  • How to generate a random unique string with more than 2^30 combination. I also wanted to reverse the process. Is this possible?

    - by Yusuf S
    I have a string which contains 3 elements: a 3 digit code (example: SIN, ABD, SMS, etc) a 1 digit code type (example: 1, 2, 3, etc) a 3 digit number (example: 500, 123, 345) Example string: SIN1500, ABD2123, SMS3345, etc.. I wanted to generate a UNIQUE 10 digit alphanumeric and case sensitive string (only 0-9/a-z/A-Z is allowed), with more than 2^30 (about 1 billion) unique combination per string supplied. The generated code must have a particular algorithm so that I can reverse the process. For example: public static void main(String[] args) { String test = "ABD2123"; String result = generateData(test); System.out.println(generateOutput(test)); //for example, the output of this is: 1jS8g4GDn0 System.out.println(generateOutput(result)); //the output of this will be ABD2123 (the original string supplied) } What I wanted to ask is is there any ideas/examples/libraries in java that can do this? Or at least any hint on what keyword should I put on Google? I tried googling using the keyword java checksum, rng, security, random number, etc and also tried looking at some random number solution (java SecureRandom, xorshift RNG, java.util.zip's checksum, etc) but I can't seem to find one? Thanks! EDIT: My use case for this program is to generate some kind of unique voucher number to be used by specific customers. The string supplied will contains 3 digit code for company ID, 1 digit code for voucher type, and a 3 digit number for the voucher nominal. I also tried adding 3 random alphanumeric (so the final digit is 7 + 3 digit = 10 digit). This is what I've done so far, but the result is not very good (only about 100 thousand combination): public static String in ="somerandomstrings"; public static String out="someotherrandomstrings"; public static String encrypt(String kata) throws Exception { String result=""; String ina=in; String outa=out; Random ran = new Random(); Integer modulus=in.length(); Integer offset= ((Integer.parseInt(Utils.convertDateToString(new Date(), "SS")))+ran.nextInt(60))/2%modulus; result=ina.substring(offset, offset+1); ina=ina+ina; ina=ina.substring(offset, offset+modulus); result=result+translate(kata, ina, outa); return result; } EDIT: I'm sorry I forgot to put the "translate" function : public static String translate(String kata,String seq1, String seq2){ String result=""; if(kata!=null&seq1!=null&seq2!=null){ String[] a=kata.split(""); for (int j = 1; j < a.length; j++) { String b=a[j]; String[]seq1split=seq1.split(""); String[]seq2split=seq2.split(""); int hint=seq1.indexOf(b)+1; String sq=""; if(seq1split.length>hint) sq=seq1split[hint]; String sq1=""; if(seq2split.length>hint) sq1=seq2split[hint]; b=b.replace(sq, sq1); result=result+b; } } return result; }

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  • Function returning MYSQL_ROW

    - by Gabe
    I'm working on a system using lots of MySQL queries and I'm running into some memory problems I'm pretty sure have to do with me not handling pointers right... Basically, I've got something like this: MYSQL_ROW function1() { string query="SELECT * FROM table limit 1;"; MYSQL_ROW return_row; mysql_init(&connection); // "connection" is a global variable if (mysql_real_connect(&connection,HOST,USER,PASS,DB,0,NULL,0)){ if (mysql_query(&connection,query.c_str())) cout << "Error: " << mysql_error(&connection); else{ resp = mysql_store_result(&connection); //"resp" is also global if (resp) return_row = mysql_fetch_row(resp); mysql_free_result(resp); } mysql_close(&connection); }else{ cout << "connection failed\n"; if (mysql_errno(&connection)) cout << "Error: " << mysql_errno(&connection) << " " << mysql_error(&connection); } return return_row; } And function2(): MYSQL_ROW function2(MYSQL_ROW row) { string query = "select * from table2 where code = '" + string(row[2]) + "'"; MYSQL_ROW retorno; mysql_init(&connection); if (mysql_real_connect(&connection,HOST,USER,PASS,DB,0,NULL,0)){ if (mysql_query(&connection,query.c_str())) cout << "Error: " << mysql_error(&conexao); else{ // My "debugging" shows me at this point `row[2]` is already fubar resp = mysql_store_result(&connection); if (resp) return_row = mysql_fetch_row(resp); mysql_free_result(resp); } mysql_close(&connection); }else{ cout << "connection failed\n"; if (mysql_errno(&connection)) cout << "Error : " << mysql_errno(&connection) << " " << mysql_error(&connection); } return return_row; } And main() is an infinite loop basically like this: int main( int argc, char* args[] ){ MYSQL_ROW row = NULL; while (1) { row = function1(); if(row != NULL) function2(row); } } (variable and function names have been generalized to protect the innocent) But after the 3rd or 4th call to function2, that only uses row for reading, row starts losing its value coming to a segfault error... Anyone's got any ideas why? I'm not sure the amount of global variables in this code is any good, but I didn't design it and only got until tomorrow to fix and finish it, so workarounds are welcome! Thanks!

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  • Difficulty creating classes and arrays of those classes C#

    - by Lucifer Fayte
    I'm trying to implement a Discrete Fourier Transformation algorithm for a project I'm doing in school. But creating a class is seeming to be difficult(which it shouldn't be). I'm using Visual Studio 2012. Basically I need a class called Complex to store the two values I get from a DFT; The real portion and the imaginary portion. This is what I have so far for that: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SoundEditor_V3 { public class Complex { public double real; public double im; public Complex() { real = 0; im = 0; } } } The problem is that it doesn't recognize the constructor as a constructor, now I'm just learning C#, but I looked it up online and this is how it's supposed to look apparently. It recognizes my constructor as a method. Why is that? Am I creating the class wrong? It's doing the same thing for my Fourier class as well. So each time I try to create a Fourier object and then use it's method...there is no such thing. example, I do this: Fourier fou = new Fourier(); fou.DFT(s, N, amp, 0); and it tells me fou is a 'field' but is used like a 'type' why is it saying that? Here is the code for my Fourier class as well: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SoundEditor_V3 { public class Fourier { //FOURIER //N = number of samples //s is the array of samples(data) //amp is the array where the complex result will be written to //start is the where in the array to start public void DFT(byte[] s, int N, ref Complex[] amp, int start) { Complex tem = new Complex(); int f; int t; for (f = 0; f < N; f++) { tem.real = 0; tem.im = 0; for (t = 0; t < N; t++) { tem.real += s[t + start] * Math.Cos(2 * Math.PI * t * f / N); tem.im -= s[t + start] * Math.Sin(2 * Math.PI * t * f / N); } amp[f].real = tem.real; amp[f].im = tem.im; } } //INVERSE FOURIER public void IDFT(Complex[] A, ref int[] s) { int N = A.Length; int t, f; double result; for (t = 0; t < N; t++) { result = 0; for (f = 0; f < N; f++) { result += A[f].real * Math.Cos(2 * Math.PI * t * f / N) - A[f].im * Math.Sin(2 * Math.PI * t * f / N); } s[t] = (int)Math.Round(result); } } } } I'm very much stuck at the moment, any and all help would be appreciated. Thank you.

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  • Rewriting Live TCP/IP (Layer 4) (i.e. Socket Layer) Streams

    - by user213060
    I have a simple problem which I'm sure someone here has done before... I want to rewrite Layer 4 TCP/IP streams (Not lower layer individual packets or frames.) Ettercap's etterfilter command lets you perform simple live replacements of Layer 4 TCP/IP streams based on fixed strings or regexes. Example ettercap scripting code: if (ip.proto == TCP && tcp.dst == 80) { if (search(DATA.data, "gzip")) { replace("gzip", " "); msg("whited out gzip\n"); } } if (ip.proto == TCP && tcp.dst == 80) { if (search(DATA.data, "deflate")) { replace("deflate", " "); msg("whited out deflate\n"); } } http://ettercap.sourceforge.net/forum/viewtopic.php?t=2833 I would like to rewrite streams based on my own filter program instead of just simple string replacements. Anyone have an idea of how to do this? Is there anything other than Ettercap that can do live replacement like this, maybe as a plugin to a VPN software or something? I would like to have a configuration similar to ettercap's silent bridged sniffing configuration between two Ethernet interfaces. This way I can silently filter traffic coming from either direction with no NATing problems. Note that my filter is an application that acts as a pipe filter, similar to the design of unix command-line filters: >[eth0] <----------> [my filter] <----------> [eth1]< What I am already aware of, but are not suitable: Tun/Tap - Works at the lower packet layer, I need to work with the higher layer streams. Ettercap - I can't find any way to do replacements other than the restricted capabilities in the example above. Hooking into some VPN software? - I just can't figure out which or exactly how. libnetfilter_queue - Works with lower layer packets, not TCP/IP streams. Again, the rewriting should occur at the transport layer (Layer 4) as it does in this example, instead of a lower layer packet-based approach. Exact code will help immensely! Thanks!

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  • Is it possible to use CSS to align these divs/spans in a table-like manner?

    - by Justin L.
    I have <div class='line'> <div class='chord_line'> <span class='chord_block'></span> <span class='chord_block'>E</span> <span class='chord_block'>B</span> <span class='chord_block'>C#m</span> <span class='chord_block'>A</span> </div> <div class='lyric_line'> <span class='lyric_block'></span> <span class='lyric_block'>Just a</span> <span class='lyric_block'>small-town girl</span> <span class='lyric_block'>living in a</span> <span class='lyric_block'>lonely world</span> </div> </div> (Excuse me for not being too familiar with proper css conventions for when to use div/spans) I want to be able to display them so that each chord_block span and lyric_block span is aligned vertically, as if they were left-aligned and on the same row of a table. For example: E B C#m A Just a small-town girl living in a lonely world (There will often be cases where an empty chord block is matched up to non-empty lyric block, and vice-versa.) I'm completely new to using CSS to align things, and have had no real understanding/experience of CSS aside from changing background colors and link styles. Is this possible in CSS? If not, how could the div/class nesting structure be revised to make this possible? I could change the spans to divs if necessary. Some things I cannot use: I can't change the structure to group things by a chord_and_lyric_block div (and have their width stretch to the length of the lyric, and stack them horizontally), because I couldn't really copy/select the lyrical lines continuously in their entirety, which is extremely critical. I'm trying to avoid a table-like solution, because this data is not tabular at all. The chord line and the lyric line are meant to be read as one continuous line, not a set of cells. Also, apart from the design philosophy reasons, I think it might have the same problems as the previous thing bullet point. If this is possible, what div/span attributes should I be using? Can you provide sample css? If this is not possible, can it be done with javascript?

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  • Keeping floated divs inline

    - by Elliott
    I'm having trouble getting my layout working correctly, I have a main div and a sidebar div these are both float: left if the screen size is resized or if its viewed on screen smaller that what I have designed on (1920x1080) then the sidebar div drops below the main content. I tried placing a wrapper around each div, but this has no effect. <div id="header"> [Header] </div> <div id="content"> [Content] </div> <div id="sideBar"> [SideBar] </div> <div id="footer"> [Footer] </div> body { width: 100%; color: #000000; background-color: #000000; margin: 0; padding: 0; } #header { width: 100%; height: 110px; background-color: #336699; color: #FFFFFF; margin: 0px; padding: 0px; } #content { float: left; margin-left: 50px; width: 70%; height: 700px; margin-top: 40px; padding: 30px; background-color: #FFFFFF; margin-bottom: 40px; } #sideBar { float: left; margin-left: 50px; width: 15%; height: 400px; margin-top: 40px; padding: 30px; background-color: #FFFFFF; } #footer { width: 100%; height: 80px; background-color: #174555; margin: 0px; padding: 0px; color: #ffffff; clear: both; } Basicly both div's should resize until a certain size is reached, then scrolling should be enabled. I'm pretty sure I have done something simple wrong but i'm not much of a design person. Example can be shown here : Link Thanks for any advice :)

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  • Perl - Calling subclass constructor from superclass (OO)

    - by Emmel
    This may turn out to be an embarrassingly stupid question, but better than potentially creating embarrassingly stupid code. :-) This is an OO design question, really. Let's say I have an object class 'Foos' that represents a set of dynamic configuration elements, which are obtained by querying a command on disk, 'mycrazyfoos -getconfig'. Let's say that there are two categories of behavior that I want 'Foos' objects to have: Existing ones: one is, query ones that exist in the command output I just mentioned (/usr/bin/mycrazyfoos -getconfig`. Make modifications to existing ones via shelling out commands. Create new ones that don't exist; new 'crazyfoos', using a complex set of /usr/bin/mycrazyfoos commands and parameters. Here I'm not really just querying, but actually running a bunch of system() commands. Affecting changes. Here's my class structure: Foos.pm package Foos, which has a new($hashref-{name = 'myfooname',) constructor that takes a 'crazyfoo NAME' and then queries the existence of that NAME to see if it already exists (by shelling out and running the mycrazyfoos command above). If that crazyfoo already exists, return a Foos::Existing object. Any changes to this object requires shelling out, running commands and getting confirmation that everything ran okay. If this is the way to go, then the new() constructor needs to have a test to see which subclass constructor to use (if that even makes sense in this context). Here are the subclasses: Foos/Existing.pm As mentioned above, this is for when a Foos object already exists. Foos/Pending.pm This is an object that will be created if, in the above, the 'crazyfoo NAME' doesn't actually exist. In this case, the new() constructor above will be checked for additional parameters, and it will go ahead and, when called using -create() shell out using system() and create a new object... possibly returning an 'Existing' one... OR As I type this out, I am realizing it is perhaps it's better to have a single: (an alternative arrangement) Foos class, that has a -new() that takes just a name -create() that takes additional creation parameters -delete(), -change() and other params that affect ones that exist; that will have to just be checked dynamically. So here we are, two main directions to go with this. I'm curious which would be the more intelligent way to go.

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  • Minutia on Objective-C Categories and Extensions.

    - by Matt Wilding
    I learned something new while trying to figure out why my readwrite property declared in a private Category wasn't generating a setter. It was because my Category was named: // .m @interface MyClass (private) @property (readwrite, copy) NSArray* myProperty; @end Changing it to: // .m @interface MyClass () @property (readwrite, copy) NSArray* myProperty; @end and my setter is synthesized. I now know that Class Extension is not just another name for an anonymous Category. Leaving a Category unnamed causes it to morph into a different beast: one that now gives compile-time method implementation enforcement and allows you to add ivars. I now understand the general philosophies underlying each of these: Categories are generally used to add methods to any class at runtime, and Class Extensions are generally used to enforce private API implementation and add ivars. I accept this. But there are trifles that confuse me. First, at a hight level: Why differentiate like this? These concepts seem like similar ideas that can't decide if they are the same, or different concepts. If they are the same, I would expect the exact same things to be possible using a Category with no name as is with a named Category (which they are not). If they are different, (which they are) I would expect a greater syntactical disparity between the two. It seems odd to say, "Oh, by the way, to implement a Class Extension, just write a Category, but leave out the name. It magically changes." Second, on the topic of compile time enforcement: If you can't add properties in a named Category, why does doing so convince the compiler that you did just that? To clarify, I'll illustrate with my example. I can declare a readonly property in the header file: // .h @interface MyClass : NSObject @property (readonly, copy) NSString* myString; @end Now, I want to head over to the implementation file and give myself private readwrite access to the property. If I do it correctly: // .m @interface MyClass () @property (readonly, copy) NSString* myString; @end I get a warning when I don't synthesize, and when I do, I can set the property and everything is peachy. But, frustratingly, if I happen to be slightly misguided about the difference between Category and Class Extension and I try: // .m @interface MyClass (private) @property (readonly, copy) NSString* myString; @end The compiler is completely pacified into thinking that the property is readwrite. I get no warning, and not even the nice compile error "Object cannot be set - either readonly property or no setter found" upon setting myString that I would had I not declared the readwrite property in the Category. I just get the "Does not respond to selector" exception at runtime. If adding ivars and properties is not supported by (named) Categories, is it too much to ask that the compiler play by the same rules? Am I missing some grand design philosophy?

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  • how to find which button has been clicked in app widgets in android?

    - by chrish
    I want to design simple app widget which has two textview and two button for previous/next. I am getting difficult to handle button click in app widget. Actually my desire is,if user click on previous button i want to show previous value and if user click on Next button i want to show next value from database. How to know which button is clicked? here i register button click listener like this public static class UpdateWidgetService extends IntentService { public UpdateWidgetService() { super("UpdateWidgetService"); } @Override protected void onHandleIntent(Intent intent) { AppWidgetManager appWidgetManager = AppWidgetManager .getInstance(this); int incomingAppWidgetId = intent.getIntExtra(EXTRA_APPWIDGET_ID, INVALID_APPWIDGET_ID); if (incomingAppWidgetId != INVALID_APPWIDGET_ID) { updateOneAppWidget(appWidgetManager, incomingAppWidgetId); } } private void updateOneAppWidget(AppWidgetManager appWidgetManager, int appWidgetId) { DatabaseManager dbManager = new DatabaseManager(this); dbManager.open(); String contactNumber, date, status, message; ArrayList<QueuedMessage> listOfQuedMessage = (ArrayList<QueuedMessage>) dbManager .fetchContactNumber(); if (listOfQuedMessage.size() == 0) Log.i("Db", "null"); else{ date = dbManager.fetchDate(); message = dbManager.fetchMessage(); status = dbManager.fetchStatus(); dbManager.closeDatabase(); RemoteViews views = new RemoteViews(this.getPackageName(), R.layout.schdulesms_appwidget_layout); views.setTextViewText(R.id.to_appwidget_saved_data, listOfQuedMessage.get(count).contacNumber); views.setTextViewText(R.id.date_appwidget_saved_data, date); views.setTextViewText(R.id.status_appwidget_saved, status); views.setTextViewText(R.id.message_appwidgset_saved_data, message); **//here i want do** if(button1){ btnNxtClick(views, appWidgetId,listOfQuedMessage.size()); }else{ btPrevClick(views, appWidgetId, listOfQuedMessage.size()); } appWidgetManager.updateAppWidget(appWidgetId, views); } } private void btnNxtClick(RemoteViews views, int appWidgetId,int sizeOfList) { Intent btnNextIntent = new Intent(this, this.getClass()); btnNextIntent.putExtra(EXTRA_APPWIDGET_ID, appWidgetId); PendingIntent btnNextPendingIntent = PendingIntent.getService(this, 0, btnNextIntent, PendingIntent.FLAG_UPDATE_CURRENT); views.setOnClickPendingIntent(R.id.btnNext, btnNextPendingIntent); } private void btPrevClick(RemoteViews views, int appWidgetId,int sizeOfList) { Intent btnNextIntent = new Intent(this, this.getClass()); btnNextIntent.putExtra(EXTRA_APPWIDGET_ID, appWidgetId); PendingIntent btnNextPendingIntent = PendingIntent.getService(this, 0, btnNextIntent, PendingIntent.FLAG_UPDATE_CURRENT); views.setOnClickPendingIntent(R.id.btnPrev, btnNextPendingIntent); } } can anyone help me out from this problem?? thanks

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  • How do I write object classes effectively when dealing with table joins?

    - by Chris
    I should start by saying I'm not now, nor do I have any delusions I'll ever be a professional programmer so most of my skills have been learned from experience very much as a hobby. I learned PHP as it seemed a good simple introduction in certain areas and it allowed me to design simple web applications. When I learned about objects, classes etc the tutor's basic examnples covered the idea that as a rule of thumb each database table should have its own class. While that worked well for the photo gallery project we wrote, as it had very simple mysql queries, it's not working so well now my projects are getting more complex. If I require data from two separate tables which require a table join I've instead been ignoring the class altogether and handling it on a case by case basis, OR, even worse been combining some of the data into the class and the rest as a separate entity and doing two queries, which to me seems inefficient. As an example, when viewing content on a forum I wrote, if you view a thread, I retrieve data from the threads table, the posts table and the user table. The queries from the user and posts table are retrieved via a join and not instantiated as an object, whereas the thread data is called using my Threads class. So how do I get from my current state of affairs to something a little less 'stupid', for want of a better word. Right now I have a DB class that deals with connection and escaping values etc, a parent db query class that deals with the common queries and methods, and all of the other classes (Thread, Upload, Session, Photo and ones thats aren't used Post, User etc ) are children of that. Do I make a big posts class that has the relevant extra attributes that I retrieve from the users (and potentially threads) table? Do I have separate classes that populate each of their relevant attributes with a single query? If so how do I do that? Because of the way my classes are written, based on what I was taught, my db update row method, or insert method both just take the attributes as an array and update all of that, if I have extra attributes from other db tables in each class then how do I rewrite those methods as obbiously updating automatically like that would result in errors? In short I think my understanding is limited right now and I'd like some pointers when it comes to the fundamentals of how to write more complex classes.

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  • Reusing my PagedList object on WCF

    - by AlexCode
    The problem: I have a custom collection PagedList<T> that is being returned from my WCF service as PagedListOfEntitySearchResultW_SH0Zpu5 when T is EntitySearchResult object. I want to reuse this PagedList<T> type between the application and the service. My scenario: I've created a PagedList<T> type that inherits from List<T>. This type is on a separated assembly that is referenced on both application and WCF service. I'm using the /reference option on the scvutil to enable the type reusing. I also don't want any arrays returned so I also use the /collection to map to the generic List type. I'm using the following svcutil command to generate the service proxy: "C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\NETFX 4.0 Tools\svcutil.exe" /collectionType:System.Collections.Generic.List`1 /reference:..\..\bin\Debug\App.Utilities.dll http://localhost/App.MyService/MyService.svc?wsdl /namespace:*,"App.ServiceReferences.MyService" /out:..\ServiceProxy\MyService.cs The PagedList object is something like: [CollectionDataContract] public partial class PagedList<T> : List<T> { public PagedList() { } /// <summary> /// Creates a new instance of the PagedList object and doesn't apply any pagination algorithm. /// The only calculated property is the TotalPages, everything else needed must be passed to the object. /// </summary> /// <param name="source"></param> /// <param name="pageNumber"></param> /// <param name="pageSize"></param> /// <param name="totalRecords"></param> public PagedList(IEnumerable<T> source, int pageNumber, int pageSize, int totalRecords) { if (source == null) source = new List<T>(); this.AddRange(source); PagingInfo.PageNumber = pageNumber; PageSize = pageSize; TotalRecords = totalRecords; } public PagedList(IEnumerable<T> source, PagingInfo paging) { this.AddRange(source); this._pagingInfo = paging; } [DataMember] public int TotalRecords { get; set; } [DataMember] public int PageSize { get; set; } public int TotalPages() { if (this.TotalRecords > 0 && PageSize > 0) return (int)Math.Ceiling((double)TotalRecords / (double)PageSize); else return 0; } public bool? HasPreviousPage() { return (PagingInfo.PageNumber > 1); } public bool? HasNextPage() { return (PagingInfo.PageNumber < TotalPages()); } public bool? IsFirstPage() { return PagingInfo.PageNumber == 1; } public bool? IsLastPage() { return PagingInfo.PageNumber == TotalPages(); } PagingInfo _pagingInfo = null; [DataMember] public PagingInfo PagingInfo { get { if (_pagingInfo == null) _pagingInfo = new PagingInfo(); return _pagingInfo; } set { _pagingInfo = value; } } }

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  • Need a hand understanding this Java code please :-)

    - by Brian
    Hi all, Just wondering if anyone would be able to take a look at this code for implementing the quicksort algorithm and answer me a few questions, please :-) public class Run { /*************************************************************************** * Quicksort code from Sedgewick 7.1, 7.2. **************************************************************************/ public static void quicksort(double[] a) { //shuffle(a); // to guard against worst-case quicksort(a, 0, a.length - 1, 0); } static void quicksort(final double[] a, final int left, final int right, final int tdepth) { if (right <= left) return; final int i = partition(a, left, right); if ((tdepth < 4) && ((i - left) > 1000)) { final Thread t = new Thread() { public void run() { quicksort(a, left, i - 1, tdepth + 1); } }; t.start(); quicksort(a, i + 1, right, tdepth + 1); try { t.join(); } catch (InterruptedException e) { throw new RuntimeException("Cancelled", e); } } else { quicksort(a, left, i - 1, tdepth); quicksort(a, i + 1, right, tdepth); } } // partition a[left] to a[right], assumes left < right private static int partition(double[] a, int left, int right) { int i = left - 1; int j = right; while (true) { while (less(a[++i], a[right])) // find item on left to swap ; // a[right] acts as sentinel while (less(a[right], a[--j])) // find item on right to swap if (j == left) break; // don't go out-of-bounds if (i >= j) break; // check if pointers cross exch(a, i, j); // swap two elements into place } exch(a, i, right); // swap with partition element return i; } // is x < y ? private static boolean less(double x, double y) { return (x < y); } // exchange a[i] and a[j] private static void exch(double[] a, int i, int j) { double swap = a[i]; a[i] = a[j]; a[j] = swap; } // shuffle the array a[] private static void shuffle(double[] a) { int N = a.length; for (int i = 0; i < N; i++) { int r = i + (int) (Math.random() * (N - i)); // between i and N-1 exch(a, i, r); } } // test client public static void main(String[] args) { int N = 5000000; // Integer.parseInt(args[0]); // generate N random real numbers between 0 and 1 long start = System.currentTimeMillis(); double[] a = new double[N]; for (int i = 0; i < N; i++) a[i] = Math.random(); long stop = System.currentTimeMillis(); double elapsed = (stop - start) / 1000.0; System.out.println("Generating input: " + elapsed + " seconds"); // sort them start = System.currentTimeMillis(); quicksort(a); stop = System.currentTimeMillis(); elapsed = (stop - start) / 1000.0; System.out.println("Quicksort: " + elapsed + " seconds"); } } My questions are: What is the purpose of the variable tdepth? Is this considered a "proper" implementation of a parallel quicksort? I ask becuase it doesn't use implements Runnable or extends Thread... If it doesn't already, is it possible to modify this code to use multiple threads? By passing in the number of threads you want to use as a parameter, for example...? Many thanks, Brian

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  • Why is there a Null Pointer Exception in this Java Code?

    - by algorithmicCoder
    This code takes in users and movies from two separate files and computes a user score for a movie. When i run the code I get the following error: Exception in thread "main" java.lang.NullPointerException at RecommenderSystem.makeRecommendation(RecommenderSystem.java:75) at RecommenderSystem.main(RecommenderSystem.java:24) I believe the null pointer exception is due to an error in this particular class but I can't spot it....any thoughts? import java.io.*; import java.lang.Math; public class RecommenderSystem { private Movie[] m_movies; private User[] m_users; /** Parse the movies and users files, and then run queries against them. */ public static void main(String[] argv) throws FileNotFoundException, ParseError, RecommendationError { FileReader movies_fr = new FileReader("C:\\workspace\\Recommender\\src\\IMDBTop10.txt"); FileReader users_fr = new FileReader("C:\\workspace\\Recommender\\src\\IMDBTop10-users.txt"); MovieParser mp = new MovieParser(movies_fr); UserParser up = new UserParser(users_fr); Movie[] movies = mp.getMovies(); User[] users = up.getUsers(); RecommenderSystem rs = new RecommenderSystem(movies, users); System.out.println("Alice would rate \"The Shawshank Redemption\" with at least a " + rs.makeRecommendation("The Shawshank Redemption", "asmith")); System.out.println("Carol would rate \"The Dark Knight\" with at least a " + rs.makeRecommendation("The Dark Knight", "cd0")); } /** Instantiate a recommender system. * * @param movies An array of Movie that will be copied into m_movies. * @param users An array of User that will be copied into m_users. */ public RecommenderSystem(Movie[] movies, User[] users) throws RecommendationError { m_movies = movies; m_users = users; } /** Suggest what the user with "username" would rate "movieTitle". * * @param movieTitle The movie for which a recommendation is made. * @param username The user for whom the recommendation is made. */ public double makeRecommendation(String movieTitle, String username) throws RecommendationError { int userNumber; int movieNumber; int j=0; double weightAvNum =0; double weightAvDen=0; for (userNumber = 0; userNumber < m_users.length; ++userNumber) { if (m_users[userNumber].getUsername().equals(username)) { break; } } for (movieNumber = 0; movieNumber < m_movies.length; ++movieNumber) { if (m_movies[movieNumber].getTitle().equals(movieTitle)) { break; } } // Use the weighted average algorithm here (don't forget to check for // errors). while(j<m_users.length){ if(j!=userNumber){ weightAvNum = weightAvNum + (m_users[j].getRating(movieNumber)- m_users[j].getAverageRating())*(m_users[userNumber].similarityTo(m_users[j])); weightAvDen = weightAvDen + (m_users[userNumber].similarityTo(m_users[j])); } j++; } return (m_users[userNumber].getAverageRating()+ (weightAvNum/weightAvDen)); } } class RecommendationError extends Exception { /** An error for when something goes wrong in the recommendation process. * * @param s A string describing the error. */ public RecommendationError(String s) { super(s); } }

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  • Subclassing and adding data members

    - by Marius
    I have an hierarchy of classes that looks like the following: class Critical { public: Critical(int a, int b) : m_a(a), m_b(b) { } virtual ~Critical() { } int GetA() { return m_a; } int GetB() { return m_b; } void SetA(int a) { m_a = a; } void SetB(int b) { m_b = b; } protected: int m_a; int m_b; }; class CriticalFlavor : public Critical { public: CriticalFlavor(int a, int b, int flavor) : Critical(a, b), m_flavor(flavor) { } virtual ~CriticalFlavor() { } int GetFlavor() { return m_flavor; } void SetFlavor(int flavor) { m_flavor = flavor; } protected: int m_flavor; }; class CriticalTwist : public Critical { public: CriticalTwist(int a, int b, int twist) : Critical(a, b), m_twist(twist) { } virtual ~CriticalTwist() { } int GetTwist() { return m_twist; } void SetTwist(int twist) { m_twist = twist; } protected: int m_twist; }; The above does not seem right to me in terms of the design and what bothers me the most is the fact that the addition of member variables seems to drive the interface of these classes (the real code that does the above is a little more complex but still embracing the same pattern). That will proliferate when in need for another "Critical" class that just adds some other property. Does this feel right to you? How could I refactor such code? An idea would be to have just a set of interfaces and use composition when it comes to the base object like the following: class Critical { public: virtual int GetA() = 0; virtual int GetB() = 0; virtual void SetA(int a) = 0; virtual void SetB(int b) = 0; }; class CriticalImpl { public: CriticalImpl(int a, int b) : m_a(a), m_b(b) { } ~CriticalImpl() { } int GetA() { return m_a; } int GetB() { return m_b; } void SetA(int a) { m_a = a; } void SetB(int b) { m_b = b; } private: int m_a; int m_b; }; class CriticalFlavor { public: virtual int GetFlavor() = 0; virtual void SetFlavor(int flavor) = 0; }; class CriticalFlavorImpl : public Critical, public CriticalFlavor { public: CriticalFlavorImpl(int a, int b, int flavor) : m_flavor(flavor), m_critical(new CriticalImpl(a, b)) { } ~CriticalFlavorImpl() { delete m_critical; } int GetFlavor() { return m_flavor; } void SetFlavor(int flavor) { m_flavor = flavor; } int GetA() { return m_critical-GetA(); } int GetB() { return m_critical-GetB(); } void SetA(int a) { m_critical-SetA(a); } void SetB(int b) { m_critical-SetB(b); } private: int m_flavor; CriticalImpl* m_critical; };

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  • Doing XML extracts with XSLT without having to read the whole DOM tree into memory?

    - by Thorbjørn Ravn Andersen
    I have a situation where I want to extract some information from some very large but regular XML files (just had to do it with a 500 Mb file), and where XSLT would be perfect. Unfortunately those XSLT implementations I am aware of (except the most expensive version of Saxon) does not support only having the necessary part of the DOM read in but reads in the whole tree. This cause the computer to swap to death. The XPath in question is //m/e[contains(.,'foobar') so it is essentially just a grep. Is there an XSLT implementation which can do this? Or an XSLT implementation which given suitable "advice" can do this trick of pruning away the parts in memory which will not be needed again? I'd prefer a Java implementation but both Windows and Linux are viable native platforms. EDIT: The input XML looks like: <log> <!-- Fri Jun 26 12:09:27 CEST 2009 --> <e h='12:09:27,284' l='org.apache.catalina.session.ManagerBase' z='1246010967284' t='ContainerBackgroundProcessor[StandardEngine[Catalina]]' v='10000'> <m>Registering Catalina:type=Manager,path=/axsWHSweb-20090626,host=localhost</m></e> <e h='12:09:27,284' l='org.apache.catalina.session.ManagerBase' z='1246010967284' t='ContainerBackgroundProcessor[StandardEngine[Catalina]]' v='10000'> <m>Force random number initialization starting</m></e> <e h='12:09:27,284' l='org.apache.catalina.session.ManagerBase' z='1246010967284' t='ContainerBackgroundProcessor[StandardEngine[Catalina]]' v='10000'> <m>Getting message digest component for algorithm MD5</m></e> <e h='12:09:27,284' l='org.apache.catalina.session.ManagerBase' z='1246010967284' t='ContainerBackgroundProcessor[StandardEngine[Catalina]]' v='10000'> <m>Completed getting message digest component</m></e> <e h='12:09:27,284' l='org.apache.catalina.session.ManagerBase' z='1246010967284' t='ContainerBackgroundProcessor[StandardEngine[Catalina]]' v='10000'> <m>getDigest() 0</m></e> ...... </log> Essentialy I want to select some m-nodes (and I know the XPath is wrong for that, it was just a quick hack), but maintain the XML layout. EDIT: It appears that STX may be what I am looking for (I can live with another transformation language), and that Joost is an implementation hereof. Any experiences? EDIT: I found that Saxon 6.5.4 with -Xmx1500m could load my XML, so this allowed me to use my XPaths right now. This is just a lucky stroke so I'd still like to solve this generically - this means scriptable which in turn means no handcrafted Java filtering first. EDIT: Oh, by the way. This is a log file very similar to what is generated by the log4j XMLLayout. The reason for XML is to be able to do exactly this, namely do queries on the log. This is the initial try, hence the simple question. Later I'd like to be able to ask more complex questions - therefore I'd like the query language to be able to handle the input file.

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  • Which network protocol to use for lightweight notification of remote apps (Delphi 2005)

    - by Chris Thornton
    I have this situation.... Client-initiated SOAP 1.1 communication between one server and let's say, tens of thousands of clients. Clients are external, coming in through our firewall, authenticated by certificate, https, etc.. They can be anywhere, and usually have their own firewalls, NAT routers, etc... They're truely external, not just remote corporate offices. They could be in a corporate/campus network, DSL/Cable, even Dialup. Currently, clients push new data to the server and pull new data from the server on 15-minute polling loop. The server currently does not push data - the client hits the "messagecount" method, to see if there is new data to pull. If 0, it sleeps for another 15 min and checks again. We're trying to get that down to 7 seconds. If this were an internal app, with one or just a few dozen clients, we'd write a cilent "listener" soap service, and would push data to it. But since they're external, sit behind their own firewalls, and sometimes private networks behind NAT routers, this is not practical. So we're left with polling on a much quicker loop. 10K clients, each checking their messagecount every 10 seconds, is going to be 1000/sec messages that will mostly just waste bandwidth, server, firewall, and authenticator resources. So I'm trying to design something better than what would amount to a self-inflicted DoS attack. I don't think it's practical to have the server send soap messages to the client (push) as this would require too much configuration at the client end. But I think there are alternatives that I don't know about. Such as: 1) Is there a way for the client to make a request for GetMessageCount() via Soap 1.1, and get the response, and then perhaps, "stay on the line" for perhaps 5-10 minutes to get additional responses in case new data arrives? i.e the server says "0", then a minute later in response to some SQL trigger (the server is C# on Sql Server, btw), knows that this client is still "on the line" and sends the updated message count of "5"? 2) Is there some other protocol that we could use to "ping" the client, using information gathered from their last GetMessageCount() request? 3) I don't even know. I guess I'm looking for some magic protocol where the client can send a GetMessageCount() request, which would include info for "oh by the way, in case the answer changes in the next hour, ping me at this address...". Also, I'm assuming that any of these "keep the line open" schemes would seriously impact the server sizing, as it would need to keep many thousands of connections open, simultaneously. That would likely impact the firewalls too, I think. Is there anything out there like that? Or am I pretty much stuck with polling? TIA, Chris

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  • How to create multiple Repository object inside a Repository class using Unit Of Work?

    - by Santosh
    I am newbie to MVC3 application development, currently, we need following Application technologies as requirement MVC3 framework IOC framework – Autofac to manage object creation dynamically Moq – Unit testing Entity Framework Repository and Unit Of Work Pattern of Model class I have gone through many article to explore an basic idea about the above points but still I am little bit confused on the “Repository and Unit Of Work Pattern “. Basically what I understand Unit Of Work is a pattern which will be followed along with Repository Pattern in order to share the single DB Context among all Repository object, So here is my design : IUnitOfWork.cs public interface IUnitOfWork : IDisposable { IPermitRepository Permit_Repository{ get; } IRebateRepository Rebate_Repository { get; } IBuildingTypeRepository BuildingType_Repository { get; } IEEProjectRepository EEProject_Repository { get; } IRebateLookupRepository RebateLookup_Repository { get; } IEEProjectTypeRepository EEProjectType_Repository { get; } void Save(); } UnitOfWork.cs public class UnitOfWork : IUnitOfWork { #region Private Members private readonly CEEPMSEntities context = new CEEPMSEntities(); private IPermitRepository permit_Repository; private IRebateRepository rebate_Repository; private IBuildingTypeRepository buildingType_Repository; private IEEProjectRepository eeProject_Repository; private IRebateLookupRepository rebateLookup_Repository; private IEEProjectTypeRepository eeProjectType_Repository; #endregion #region IUnitOfWork Implemenation public IPermitRepository Permit_Repository { get { if (this.permit_Repository == null) { this.permit_Repository = new PermitRepository(context); } return permit_Repository; } } public IRebateRepository Rebate_Repository { get { if (this.rebate_Repository == null) { this.rebate_Repository = new RebateRepository(context); } return rebate_Repository; } } } PermitRepository .cs public class PermitRepository : IPermitRepository { #region Private Members private CEEPMSEntities objectContext = null; private IObjectSet<Permit> objectSet = null; #endregion #region Constructors public PermitRepository() { } public PermitRepository(CEEPMSEntities _objectContext) { this.objectContext = _objectContext; this.objectSet = objectContext.CreateObjectSet<Permit>(); } #endregion public IEnumerable<RebateViewModel> GetRebatesByPermitId(int _permitId) { // need to implment } } PermitController .cs public class PermitController : Controller { #region Private Members IUnitOfWork CEEPMSContext = null; #endregion #region Constructors public PermitController(IUnitOfWork _CEEPMSContext) { if (_CEEPMSContext == null) { throw new ArgumentNullException("Object can not be null"); } CEEPMSContext = _CEEPMSContext; } #endregion } So here I am wondering how to generate a new Repository for example “TestRepository.cs” using same pattern where I can create more then one Repository object like RebateRepository rebateRepo = new RebateRepository () AddressRepository addressRepo = new AddressRepository() because , what ever Repository object I want to create I need an object of UnitOfWork first as implmented in the PermitController class. So if I would follow the same in each individual Repository class that would again break the priciple of Unit Of Work and create multiple instance of object context. So any idea or suggestion will be highly appreciated. Thank you

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  • Conceptual inheritance implementation

    - by TheSENDER
    Hi there, I'm writing a spatial data structure and I have a doubt about what's the best NODE implementation. According to my design I have an abstract node entity and three classes which inherit from it: EMPTYNODE, FULLNODE, INTERNALNODE. The first one has no particular data. The second one has 1 reference to a generic element. The third one has 2 references to other nodes. I have found several ways to implement this situation (that I have already coded) but I can't decide what's the best. The first solution that I have found is to use a single class Node that potentially performs all the operation in this way: private static class Node { private Elem elem = null; private Node left = null, right = null; public Elem getElem() { assert isFull(); return elem; } public boolean isEmpty() { return elem == null && left == null; } public boolean isFull() { return elem != null; } public boolean isInternal() { return elem == null && left != null; } } The second solution is to write an explicit division by classes where every class offers only its methods. Obviously in this way we are obliged to perform several casts to the node objects. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); } private static class FullNode extends Node{ private ITriangle elem; @Override public boolean isEmpty() { return false; } @Override public final boolean isFull() { return true; } @Override public final boolean isInternal() { return false; } public Elem getElem() { return elem; } } The third one solution is to use the inheritance allowing every classes to offer all the methods, but the object type should by check by "isEmpty()" and similar methods. In case of wrong call we'll throw an exception. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); public abstract Elem getElem(); } private static class Empty extends Node{ @Override public boolean isEmpty() { return true; } @Override public final boolean isFull() { return false; } @Override public final boolean isInternal() { return false; } @Override public Elem getElem() { throw new AssertionError(); } } What do you think about these three solutions? Which one would you use? Any other ideas? Thanks for your help. Every idea will be appreciated.

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  • New to MVC. Actionscript 3.0 Appreciate your help.

    - by Combustion007
    Hello Everyone, I am new to design patterns and am trying to learn the MVC implementation. I have written four classes: DataModel DataView DataController Main Main serves as the application facade. The main FLA is called HelloWorld. I have a symbol called "Box" in HelloWorld. I just would like to add an instance of the "Box" on the stage. Eventually I would like to place a button and when the button is clicked, the Box instance color will be changed. I would appreciate any help, please help me figure out what am I doing wrong. Here are my Classes: DATAMODEL CLASS: package { import flash.events.*; public class DataModel extends EventDispatcher { public static const UPDATE:String = "modelUpdate"; private var _color:Number = (Math.round(Math.random()* 0xffffff)); public function DataModel() { trace("DATA MODEL INIT"); } public function get color():Number { return _color; } public function set color(p:Number):void { _color = p; notifyObserver(); } public function notifyObserver():void { dispatchEvent(new Event(DataModel.UPDATE)); } } } //DATACONTROLLER CLASS: package { import flash.events.; import flash.display.; import flash.errors.*; public class DataController { private var _model:DataModel; public function DataController(m:DataModel) { trace("DATACONTROLLER INIT"); _model = m; } } } DATAVIEW CLASS: package { import flash.events.; import flash.display.; import flash.errors.*; public class DataView extends Sprite { private var _model:DataModel; private var _controller:DataController; private var b:Box; public function DataView(m:DataModel, c:DataController) { _model = m; _controller = c; b = new Box(); b.x = b.y = 100; addChild(b); } } } And Finally THE FACADE: package { import flash.display.; import flash.events.; import flash.text.; import flash.errors.; public class Main extends Sprite { private var _model:DataModel; private var _controller:DataController; private var _view:DataView; public function Main(m:DataModel, c:DataController, v:DataView) { _model = m; _controller = c; _view = v; addChild(v); } } } When I test the movie: I get this error: ArgumentError: Error #1063: Argument count mismatch on Main(). Expected 3, got 0. Thanks alot.

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  • Multiple choice test GUI with serialization of Q&A

    - by Bobby
    I'm working on a project for school in Java programming. I need to design a GUI that will take in questions and answers and store them in a file. It should be able to contain an unlimited number of questions. We have covered binary I/O. How do I write the input they give to a file? How would I go about having them add multiple questions from this GUI? package multiplechoice; import java.awt.*; import javax.swing.*; public class MultipleChoice extends JFrame { public MultipleChoice() { /* * Setting Layout */ setLayout(new GridLayout(10,10)); /* * First Question */ add(new JLabel("What is the category of the question?: ")); JTextField category = new JTextField(); add(category); add(new JLabel("Please enter the question you wish to ask: ")); JTextField question = new JTextField(); add(question); add(new JLabel("Please enter the correct answer: ")); JTextField correctAnswer = new JTextField(); add(correctAnswer); add(new JLabel("Please enter a reccomended answer to display: ")); JTextField reccomendedAnswer = new JTextField(); add(reccomendedAnswer); add(new JLabel("Please enter a choice for multiple choice option " + "A")); JTextField A = new JTextField(); add(A); add(new JLabel("Please enter a choice for multiple choice option " + "B")); JTextField B = new JTextField(); add(B); add(new JLabel("Please enter a choice for multiple choice option " + "C")); JTextField C = new JTextField(); add(C); add(new JLabel("Please enter a choice for multiple choice option " + "D")); JTextField D = new JTextField(); add(D); add(new JButton("Compile Questions")); add(new JButton("Next Question")); } public static void main(String[] args) { /* * Creating JFrame to contain questions */ FinalProject frame = new FinalProject(); // FileOutputStream output = new FileOutputStream("Questions.dat"); JPanel panel = new JPanel(); // button.setLayout(); // frame.add(panel); panel.setSize(100,100); // button.setPreferredSize(new Dimension(100,100)); frame.setTitle("FinalProject"); frame.setSize(600, 400); frame.setLocationRelativeTo(null); // Center the frame frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }

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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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  • Using Entity Framework 4.0 with Code-First and POCO: How to Get Parent Object with All its Children

    - by SirEel
    I'm new to EF 4.0, so maybe this is an easy question. I've got VS2010 RC and the latest EF CTP. I'm trying to implement the "Foreign Keys" code-first example on the EF Team's Design Blog, http://blogs.msdn.com/efdesign/archive/2009/10/12/code-only-further-enhancements.aspx. public class Customer { public int Id { get; set; public string CustomerDescription { get; set; public IList<PurchaseOrder> PurchaseOrders { get; set; } } public class PurchaseOrder { public int Id { get; set; } public int CustomerId { get; set; } public Customer Customer { get; set; } public DateTime DateReceived { get; set; } } public class MyContext : ObjectContext { public RepositoryContext(EntityConnection connection) : base(connection){} public IObjectSet<Customer> Customers { get {return base.CreateObjectSet<Customer>();} } } I use a ContextBuilder to configure MyContext: { var builder = new ContextBuilder<MyContext>(); var customerConfig = _builder.Entity<Customer>(); customerConfig.Property(c => c.Id).IsIdentity(); var poConfig = _builder.Entity<PurchaseOrder>(); poConfig.Property(po => po.Id).IsIdentity(); poConfig.Relationship(po => po.Customer) .FromProperty(c => c.PurchaseOrders) .HasConstraint((po, c) => po.CustomerId == c.Id); ... } This works correctly when I'm adding new Customers, but not when I try to retrieve existing Customers. This code successfully saves a new Customer and all its child PurchaseOrders: using (var context = builder.Create(connection)) { context.Customers.AddObject(customer); context.SaveChanges(); } But this code only retrieves Customer objects; their PurchaseOrders lists are always empty. using (var context = _builder.Create(_conn)) { var customers = context.Customers.ToList(); } What else do I need to do to the ContextBuilder to make MyContext always retrieve all the PurchaseOrders with each Customer?

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