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• What Counts for a DBA: Skill

  - by drsql

  “Practice makes perfect:” right? Well, not exactly. The reality of it all is that this saying is an untrustworthy aphorism. I discovered this in my “younger” days when I was a passionate tennis player, practicing and playing 20+ hours a week. No matter what my passion level was, without some serious coaching (and perhaps a change in dietary habits), my skill level was never going to rise to a level where I could make any money at the sport that involved something other than selling tennis balls at a sporting goods store. My game may have improved with all that practice but I had too many bad practices to overcome. Practice by itself merely reinforces what we know and what we can figure out naturally. The truth is actually closer to the expression used by Vince Lombardi: “Perfect practice makes perfect.” So how do you get to become skilled as a DBA if practice alone isn’t sufficient? Hit the Internet and start searching for SQL training and you can find 100 different sites. There are also hundreds of blogs, magazines, books, conferences both onsite and virtual. But then how do you know who is good? Unfortunately often the worst guide can be to find out the experience level of the writer. Some of the best DBAs are frighteningly young, and some got their start back when databases were stored on stacks of paper with little holes in it. As a programmer, is it really so hard to understand normalization? Set based theory? Query optimization? Indexing and performance tuning? The biggest barrier often is previous knowledge, particularly programming skills cultivated before you get started with SQL. In the world of technology, it is pretty rare that a fresh programmer will gravitate to database programming. Database programming is very unsexy work, because without a UI all you have are a bunch of text strings that you could never impress anyone with. Newbies spend most of their time building UIs or apps with procedural code in C# or VB scoring obvious interesting wins. Making matters worse is that SQL programming requires mastery of a much different toolset than most any mainstream programming skill. Instead of controlling everything yourself, most of the really difficult work is done by the internals of the engine (written by other non-relational programmers…we just can’t get away from them.) So is there a golden road to achieving a high skill level? Sadly, with tennis, I am pretty sure I’ll never discover it. However, with programming it seems to boil down to practice in applying the appropriate techniques for whatever type of programming you are doing. Can a C# programmer build a great database? As long as they don’t treat SQL like C#, absolutely. Same goes for a DBA writing C# code. None of this stuff is rocket science, as long as you learn to understand that different types of programming require different skill sets and you as a programmer must recognize the difference between one of the procedural languages and SQL and treat them differently. Skill comes from practicing doing things the right way and making “right” a habit.

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• Why is software quality so problematic?

  - by Yuval A

  Even when viewing the subject in the most objective way possible, it is clear that software, as a product, generally suffers from low quality. Take for example a house built from scratch. Usually, the house will function as it is supposed to. It will stand for many years to come, the roof will support heavy weather conditions, the doors and the windows will do their job, the foundations will not collapse even when the house is fully populated. Sure, minor problemsdo occur, like a leaking faucet or a bad paint job, but these are not critical. Software, on the other hand is much more susceptible to suffer from bad quality: unexpected crashes, erroneous behavior, miscellaneous bugs, etc. Sure, there are many software projects and products which show high quality and are very reliable. But lots of software products do not fall in this category. Take into consideration paradigms like TDD which its popularity is on the rise in the past few years. Why is this? Why do people have to fear that their software will not work or crash? (Do you walk into a house fearing its foundations will collapse?) Why is software - subjectively - so full of bugs? Possible reasons: Modern software engineering exists for only a few decades, a small time period compared to other forms of engineering/production. Software is very complicated with layers upon layers of complexity, integrating them all is not trivial. Software development is relatively easy to start with, anyone can write a simple program on his PC, which leads to amateur software leaking into the market. Tight budgets and timeframes do not allow complete and high quality development and extensive testing. How do you explain this issue, and do you see software quality advancing in the near future?

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• Worse is better. Is there an example?

  - by J.F. Sebastian

  Is there a widely-used algorithm that has time complexity worse than that of another known algorithm but it is a better choice in all practical situations (worse complexity but better otherwise)? An acceptable answer might be in a form: There are algorithms A and B that have O(N**2) and O(N) time complexity correspondingly, but B has such a big constant that it has no advantages over A for inputs less then a number of atoms in the Universe. Examples highlights from the answers: Simplex algorithm -- worst-case is exponential time -- vs. known polynomial-time algorithms for convex optimization problems. A naive median of medians algorithm -- worst-case O(N**2) vs. known O(N) algorithm. Backtracking regex engines -- worst-case exponential vs. O(N) Thompson NFA -based engines. All these examples exploit worst-case vs. average scenarios. Are there examples that do not rely on the difference between the worst case vs. average case scenario? Related: The Rise of ``Worse is Better''. (For the purpose of this question the "Worse is Better" phrase is used in a narrower (namely -- algorithmic time-complexity) sense than in the article) Python's Design Philosophy: The ABC group strived for perfection. For example, they used tree-based data structure algorithms that were proven to be optimal for asymptotically large collections (but were not so great for small collections). This example would be the answer if there were no computers capable of storing these large collections (in other words large is not large enough in this case). Coppersmith–Winograd algorithm for square matrix multiplication is a good example (it is the fastest (2008) but it is inferior to worse algorithms). Any others? From the wikipedia article: "It is not used in practice because it only provides an advantage for matrices so large that they cannot be processed by modern hardware (Robinson 2005)."

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• Working around MySQL error "Deadlock found when trying to get lock; try restarting transaction"

  - by Anon Guy

  Hi all: I have a MySQL table with about 5,000,000 rows that are being constantly updated in small ways by parallel Perl processes connecting via DBI. The table has about 10 columns and several indexes. One fairly common operation gives rise to the following error sometimes: DBD::mysql::st execute failed: Deadlock found when trying to get lock; try restarting transaction at Db.pm line 276. The SQL statement that triggers the error is something like this: UPDATE file_table SET a_lock = 'process-1234' WHERE param1 = 'X' AND param2 = 'Y' AND param3 = 'Z' LIMIT 47 The error is triggered only sometimes. I'd estimate in 1% of calls or less. However, it never happened with a small table and has become more common as the database has grown. Note that I am using the a_lock field in file_table to ensure that the four near-identical processes I am running do not try and work on the same row. The limit is designed to break their work into small chunks. I haven't done much tuning on MySQL or DBD::mysql. MySQL is a standard Solaris deployment, and the database connection is set up as follows: my $dsn = "DBI:mysql:database=" . $DbConfig::database . ";host=${DbConfig::hostname};port=${DbConfig::port}"; my $dbh = DBI->connect($dsn, $DbConfig::username, $DbConfig::password, { RaiseError => 1, AutoCommit => 1 }) or die $DBI::errstr; I have seen online that several other people have reported similar errors and that this may be a genuine deadlock situation. I have two questions: What exactly about my situation is causing the error above? Is there a simple way to work around it or lessen its frequency? For example, how exactly do I go about "restarting transaction at Db.pm line 276"? Thanks in advance.

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• Mysqli results memory usage

  - by Poe

  Why is the memory consumption in this query continuing to rise as the internal pointer progresses through loop? How to make this more efficient and lean? $link = mysqli_connect(...); $result = mysqli_query($link,$query); // 403,268 rows in result set while ($row = mysqli_fetch_row($result)) { // print time, (get memory usage), -- row number } mysqli_free_result(); mysqli_close($link); /* 06:55:25 (1240336) -- Run query 06:55:26 (39958736) -- Query finished 06:55:26 (39958784) -- Begin loop 06:55:26 (39960688) -- Row 0 06:55:26 (45240712) -- Row 10000 06:55:26 (50520712) -- Row 20000 06:55:26 (55800712) -- Row 30000 06:55:26 (61080712) -- Row 40000 06:55:26 (66360712) -- Row 50000 06:55:26 (71640712) -- Row 60000 06:55:26 (76920712) -- Row 70000 06:55:26 (82200712) -- Row 80000 06:55:26 (87480712) -- Row 90000 06:55:26 (92760712) -- Row 100000 06:55:26 (98040712) -- Row 110000 06:55:26 (103320712) -- Row 120000 06:55:26 (108600712) -- Row 130000 06:55:26 (113880712) -- Row 140000 06:55:26 (119160712) -- Row 150000 06:55:26 (124440712) -- Row 160000 06:55:26 (129720712) -- Row 170000 06:55:27 (135000712) -- Row 180000 06:55:27 (140280712) -- Row 190000 06:55:27 (145560712) -- Row 200000 06:55:27 (150840712) -- Row 210000 06:55:27 (156120712) -- Row 220000 06:55:27 (161400712) -- Row 230000 06:55:27 (166680712) -- Row 240000 06:55:27 (171960712) -- Row 250000 06:55:27 (177240712) -- Row 260000 06:55:27 (182520712) -- Row 270000 06:55:27 (187800712) -- Row 280000 06:55:27 (193080712) -- Row 290000 06:55:27 (198360712) -- Row 300000 06:55:27 (203640712) -- Row 310000 06:55:27 (208920712) -- Row 320000 06:55:27 (214200712) -- Row 330000 06:55:27 (219480712) -- Row 340000 06:55:27 (224760712) -- Row 350000 06:55:27 (230040712) -- Row 360000 06:55:27 (235320712) -- Row 370000 06:55:27 (240600712) -- Row 380000 06:55:27 (245880712) -- Row 390000 06:55:27 (251160712) -- Row 400000 06:55:27 (252884360) -- End loop 06:55:27 (1241264) -- Free */

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• How large a role does subjectiveness play in programming?

  - by Bob

  I often read about the importance of readability and maintainability. Or, I read very strong opinions about which syntax features are bad or good. Or discussions about the values of certain paradigms, like OOP. Aside from that, this same question floats about in my mind whenever I read debates on SO or Meta about subjective questions. Or read questions about best practices and sometimes find myself or others disagreeing. What role does subjectiveness play within the programming realm? Sometimes I think it plays a large role. Software developers are engineers in a way, but also people. A large part of programming is dealing with code that's human readable. This is very different from Math or Physics or other disciplines with very exact and structured rules. Here the exact structure and rules are largely up in the air, changeable on a whim, and hence the amount of languages in existence. And one person may find one language very readable, and another person may find their own language the most comforting. The same with practices. One person may not like certain accepted practices. I myself find splitting classes into different files very unreadable, for instance. But, I can't say rules haven't helped in general. Certain practices have and do make life easier. And new languages have given rise to syntax and structure that make life easier. There's certainly been a progression towards code that is easier to read and maintain even given a largely diverse group of people. So maybe these things aren't as subjective as I thought. It reminds me, in a way, of UI design. Certainly it's subjective, but then there's an entire discipline involved in crafting good UI and it tends to work. Is there something non-subjective about the ideas behind maintainability, readability, and other best practices? Is there something tangible to grasp when one develops a new language or thinks of new practices?

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• .NET Graphics.ScaleTransform converts print job to bitmap. Any other way to scale text?

  - by Philip Dunaway

  I'm using Graphics.ScaleTransform to stretch lines of text so they fit the width of the page, and then printing that page. However, this converts the print job to a bitmap - for a print with many pages this causes the size of the print job to rise to obscene proportions, and slows down printing immensely. If I don't scale like this, the print job remains very small as it is just sending text print commands to the printer. My question is, is there any way other than using Graphics.ScaleTransform to stretch the width of the text? Sample code to demonstrate this is below (would be called with Print.Test(True) and Print.Test(False) to show the effects of scaling on print job): Imports System.Drawing Imports System.Drawing.Printing Imports System.Drawing.Imaging Public Class Print Dim FixedFont As Font Dim Area As RectangleF Dim CharHeight As Double Dim CharWidth As Double Dim Scale As Boolean Const CharsAcross = 80 Const CharsDown = 66 Const TestString = "!""#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~" Private Sub PagePrinter(ByVal sender As Object, ByVal e As PrintPageEventArgs) Dim G As Graphics = e.Graphics If Scale Then Dim ws = Area.Width / G.MeasureString(Space(CharsAcross).Replace(" ", "X"), FixedFont).Width G.ScaleTransform(ws, 1) End If For CurrentLine = 1 To CharsDown G.DrawString(Mid(TestString & TestString & TestString, CurrentLine, CharsAcross), FixedFont, Brushes.Black, 0, Convert.ToSingle(CharHeight * (CurrentLine - 1))) Next e.HasMorePages = False End Sub Public Shared Sub Test(ByVal Scale As Boolean) Dim OutputDocument As New PrintDocument With OutputDocument Dim DP As New Print .PrintController = New StandardPrintController .DefaultPageSettings.Landscape = False DP.Area = .DefaultPageSettings.PrintableArea DP.CharHeight = DP.Area.Height / CharsDown DP.CharWidth = DP.Area.Width / CharsAcross DP.Scale = Scale DP.FixedFont = New Font("Courier New", DP.CharHeight / 100, FontStyle.Regular, GraphicsUnit.Inch) .DocumentName = "Test print (with" & IIf(Scale, "", "out") & " scaling)" AddHandler .PrintPage, AddressOf DP.PagePrinter .Print() End With End Sub End Class

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• Chrome is leaking memory, when jQuery is used on events?

  - by user269386

  Hi, I'm experiencing an increase of memory usage, when I use the jQuery-eventhandling in Chrome. I've tested it with IE and FF as well, but there I couldn't see a suspicious rise of memory-usage, compared to Chrome. I'm using Chrome version 4.0.223.16 (unfortunately I'm forced to use this version, here) Simple example here. Just scroll with the mousewheel in the red box and open the Chrome-taskmanager and you will see an increase of memory which won't be released anymore: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <script type="text/javascript" src="js/libs/jquery-1.4.2.min.js"></script> <script type="text/javascript"> jQuery(function () { jQuery("#div1").bind("mousewheel", function (event) { event.preventDefault(); }); }); </script> </head> <body> <div id="div1" style="width: 100px; height: 100px; background-color: red;"></div> </body> </html> Does anyone have experienced the same problem (or is it maybe solvend with a different version of chrome)? And does anyone have a fix for it? thanks

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• Windows 7 Aero Theme Progress Bar Bug?

  - by jmatthias

  I have ran into what I consider to be a progress bar bug on Windows 7. To demonstrate the bug I created a WinForm application with a button and a progress bar. In the button's 'on-click' handle I have the following code. private void buttonGo_Click(object sender, EventArgs e) { this.progressBar.Minimum = 0; this.progressBar.Maximum = 100; this.buttonGo.Text = "Busy"; this.buttonGo.Update(); for (int i = 0; i <= 100; ++i) { this.progressBar.Value = i; this.Update(); System.Threading.Thread.Sleep(10); } this.buttonGo.Text = "Ready"; } The expected behavior is for the progress bar to advance to 100% and then the button text to change to 'Ready'. However, when developing this code on Windows 7, I noticed that the progress bar would rise to about 75% and then the button text would change to 'Ready'. Assuming the code is synchronous, this should not happen! On further testing I found that the exact same code running on Windows Server 2003 produced the expected results. Furthermore, choosing a non aero theme on Windows 7 produces the expected results. In my mind, this seems like a bug. Often it is very hard to make a progress bar accurate when the long operation involves complex code but in my particular case it was very straight forward and so I was little disappointed when I found the progress control did not accurately represent the progress. Has anybody else noticed this behavior? Has anybody found a workaround?

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• SQL Server INSERT, Scope_Identity() and physical writing to disc

  - by TheBlueSky

  Hello everyone, I have a stored procedure that does, among other stuff, some inserts in different table inside a loop. See the example below for clearer understanding: INSERT INTO T1 VALUES ('something') SET @MyID = Scope_Identity() ... some stuff go here INSERT INTO T2 VALUES (@MyID, 'something else') ... The rest of the procedure These two tables (T1 and T2) have an IDENTITY(1, 1) column in each one of them, let's call them ID1 and ID2; however, after running the procedure in our production database (very busy database) and having more than 6250 records in each table, I have noticed one incident where ID1 does not match ID2! Although normally for each record inserted in T1, there is record inserted in T2 and the identity column in both is incremented consistently. The "wrong" records were something like that: ID1 Col1 ---- --------- 4709 data-4709 4710 data-4710 ID2 ID1 Col1 ---- ---- --------- 4709 4710 data-4709 4710 4709 data-4710 Note the "inverted", ID1 in the second table. Knowing not that much about SQL Server underneath operations, I have put the following "theory", maybe someone can correct me on this. What I think is that because the loop is faster than physically writing to the table, and/or maybe some other thing delayed the writing process, the records were buffered. When it comes the time to write them, they were wrote in no particular order. Is that even possible if no, how to explain the above mentioned scenario? If yes, then I have another question to rise. What if the first insert (from the code above) got delayed? Doesn't that mean I won't get the correct IDENTITY to insert into the second table? If the answer of this is also yes, what can I do to insure the insertion in the two tables will happen in sequence with the correct IDENTITY? I appreciate any comment and information that help me understand this. Thanks in advance.

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• Memory leaks while using array of double

  - by Gacek

  I have a part of code that operates on large arrays of double (containing about 6000 elements at least) and executes several hundred times (usually 800) . When I use standard loop, like that: double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... } The memory usage rises for about 40MB (from 40MB at the beggining of the loop, to the 80MB at the end). When I force to use the garbage collector to execute at every iteration, the memory usage stays at the level of 40MB (the rise is unsignificant). double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... GC.Collect() } But the execution time is 3 times longer! (it is crucial) How can I force the C# to use the same area of memory instead of allocating new ones? Note: I have the access to the code of someObject class, so if it would be needed, I can change it.

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• MySQL running on an EC2 m1.small instance has high load but low memory usage, possible resolutions?

  - by Tosh

  I have a MySQL server 5.0.75 Ubuntu, on an m1.small instance running on Amazon's EC2 as part of an application. During peak usage the server load will rise very high, while the memory usage stays low and the application server is no longer responsive since it's waiting for query results. The application server has only 5-8 apache processes running (mod_perl processes). The data directory uses only 140MB of data so the MyIsam tables aren't very big. The queries are pretty complicated with some big joins being performed, and the application makes a lot of queries. mysqltuner reports everything OK except "Maximum possible memory usage: 1.7G (99% of installed RAM)" but I'm nowhere close to using that. My question is, where should I be looking to fix this? Is this something that can be tuned away, or do I just need a larger instance/server? Googling indicates either or also upgrading MySQL server. Any pointers in the right direction would be greatly appreciated, thanks! EDIT: I just discovered this in my slow queries log: # Time: 101116 11:17:00 # User@Host: user[pass] @ [host] # Query_time: 4063 Lock_time: 1035 Rows_sent: 0 Rows_examined: 19960174 SELECT * FROM contacts WHERE contacts.contact_id IN (SELECT external_id FROM contact_relations WHERE external_table = 'contacts' AND contact_id IN (SELECT contact_id FROM contacts WHERE (company_name like '%%butan%%%' OR country like '%%butan%%%' OR city like '%%butan%%%' OR email1 like '%%butan%%%') AND (company_name is not null and company_name != ''))); Which actually brings up a different but related question: If I have a contact table containing: John Smith,The Fun Factory,555-1212,[email protected] What's the best way to search for that record using "factory" as a search key? Fulltext rarely seems to find items in the middle of a word, for example "actor" should bring up "Factory"

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• How To Correctly Specify A Default Value For A String Field In A PHP/MySQL Prepared Statement

  - by Joshua

  I'm trying to debug some auto-generated code, but I am a mySQL noob. Everything goes fine ultil the "prepare" line below, and then for some reason $mysqli_stmt is false, yielding the stated error. Could it have something to do with the SQL_MODE = 'ANSI'? The failure seems to have something to do with the string 'xxx' below, but it still happens no matter what I change it to. This value is meant to be a default value for the TickerDigest field, but strangely if I change 'xxx' to 'c_u_TickerDigest', then it suddenly works, but the TickerDigest field is inserted as 'null' when I look in the database. $mysqli = mysqli_init(); $mysqli->options(MYSQLI_INIT_COMMAND, "SET SQL_MODE = 'ANSI'"); $mysqli->real_connect(SR_Host,SR_Username,SR_Password,SR_Database) or die('Unable to connect to Database'); $sql_stmt = 'INSERT INTO "t_sr_u_Product"("c_u_Name", "c_u_Code", "c_u_TickerDigest") VALUES (?, ?, "xxx")'; $mysqli_stmt = $mysqli->prepare($sql_stmt); Fatal error: Uncaught exception 'Exception' with message 'INSERT INTO "t_sr_u_Product"("c_u_Name", "c_u_Code", "c_u_TickerDigest") VALUES (?, ?, "xxx"): prepare statement failed: Unknown column 'xxx' in 'field list'' in P:\StarRise\SandBox\GateKeeper\Rise\srIProduct.php on line 18 I'm hopeful what's going wrong is fairly simple, since I'm almost completely ignorant about SQL.

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• Determining Best Table Structure for MySQL Performance

  - by Joe Majewski

  I'm working on a browser-based RPG for one of my websites, and right now I'm trying to determine the best way to organize my SQL tables for performance and maintenance. Here's my question: Does the number of columns in an SQL table affect the speed in which it can be queried? I am not a newbie when it comes to PHP or MySQL. I used to develop things with the common goal of getting them to work, but I've recently advanced to the stage where a functional program is not good enough unless it's fast and reliable. Anyways, right now I have a members table that has around 15 columns. It contains information such as the player's username, password, email, logins, page views, etcetera. It doesn't contain any information on the player's progress in the game, however. If I added columns for things such as army size, gold, turns, and whatnot, then it could easily rise to around 40 or 50 total columns. Oh, and my database structure IS normalized. Will a table with 50 columns that gets constantly queried be a bad idea? Should I split it into two tables; one for the user's general information and one for the user's game statistics? I know I could check the query time myself, but I haven't actually created the tables yet and I think I'd be better off with some professional advice on this important decision for my game. Thank you for your time! :)

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• Ruby, Python, or PHP?

  - by Gabe

  And so we return to the age old question - but with a few twists. This morning, I searched and read up on which web development language to learn first. I'm thinking Ruby, Python, or perhaps PHP. But I have a few questions before deciding. Background: I'm a year into C++ (through school), but want to get into web development. I have all summer to commit to one language, learn it, do some projects, get up some websites, and so on. Now my questions (and these are assuming that I should choose between Ruby, Python, and PHP - if I should choose a different language, let me know.): I hope to use whichever language I learn for websites/web apps. Some of the threads on stackoverflow suggested Python was the best overall language, but others were unanimous that Ruby was best specifically for web development. For a first language suited towards web development, which language do you recommend, and why? This might tie into the first question, but which language looks most promising for future work, future personal projects, and basically the future in general? I'm just a freshman in college. Ideally, the language I choose would be on the rise, community-wise and opportunity-wise. (One reason I'm leaning towards Ruby is that it seems a lot of the newer tech startups/successes are using it.)

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• Is there a standard SQL Table design for overriding 'big picture' default values with lower level de

  - by RichardHowells

  Here's an example. Suppose we are trying to calculate a service charge. Say sales in the USA attract a 10 dollar charge, sales in the UK attract a 20 dollar charge So far it's easy - we are starting to imagine a table that lists charges by country. Now lets assume that Alaska and Hawaii are treated as special cases they are both 15 dollars That suggests a table with states, Alaska and Hawaii are charged at 15, but presumably we need 48 (redundant) rows all saying 10. This gives us a maintainance problem, our user only wants to type 10 once NOT 48 times. It does not sit well with the UK either. The UK does not have states. Suppose we throw in another couple of cross cutting rules. If you order by phone there is a 10% supplement on the charge. If you order via the web there is a 10% discount. But for some reason best known to the owners of the business the web/phone supplement/discount are not applied in Hawaii. It seems to me that this is quite a common kind of problem and there is probably a well known arrangement of tables to store the data. Most cases get handled by broad brush answers, but there are some very detailed low level variations that give rise to a huge number of theoretical combinations, most of which are not used.

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• QLearning and never-ending episodes

  - by devoured elysium

  Let's imagine we have an (x,y) plane where a robot can move. Now we define the middle of our world as the goal state, which means that we are going to give a reward of 100 to our robot once it reaches that state. Now, let's say that there are 4 states(which I will call A,B,C,D) that can lead to the goal state. The first time we are in A and go to the goal state, we will update our QValues table as following: Q(state = A, action = going to goal state) = 100 + 0 One of 2 things can happen. I can end the episode here, and start a different one where the robot has to find again the goal state, or I can continue exploring the world even after I found the goal state. If I try to do this, I see a problem though. If I am in the goal state and go back to state A, it's Qvalue will be the following: Q(state = goalState, action = going to A) = 0 + gamma * 100 Now, if I try to go again to the goal state from A: Q(state = A, action = going to goal state) = 100 + gamma * (gamma * 100) Which means that if I keep doing this, as 0 <= gamma <= 0, both qValues are going to rise forever. Is this the expected behavior of QLearning? Am I doing something wrong? If this is the expected behavior, can't this lead to problems? I know that probabilistically, all the 4 states(A,B,C and D), will grow at the same rate, but even so it kinda bugs me having them growing forever. The ideia of allowing the agent to continue exploring even after finding the goal has to do with that the nearer he is from the goal state, the more likely it is to being in states that can be updated at the moment.

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• SQL SERVER – How to Recover SQL Database Data Deleted by Accident

  - by Pinal Dave

  In Repair a SQL Server database using a transaction log explorer, I showed how to use ApexSQL Log, a SQL Server transaction log viewer, to recover a SQL Server database after a disaster. In this blog, I’ll show you how to use another SQL Server disaster recovery tool from ApexSQL in a situation when data is accidentally deleted. You can download ApexSQL Recover here, install, and play along. With a good SQL Server disaster recovery strategy, data recovery is not a problem. You have a reliable full database backup with valid data, a full database backup and subsequent differential database backups, or a full database backup and a chain of transaction log backups. But not all situations are ideal. Here we’ll address some sub-optimal scenarios, where you can still successfully recover data. If you have only a full database backup This is the least optimal SQL Server disaster recovery strategy, as it doesn’t ensure minimal data loss. For example, data was deleted on Wednesday. Your last full database backup was created on Sunday, three days before the records were deleted. By using the full database backup created on Sunday, you will be able to recover SQL database records that existed in the table on Sunday. If there were any records inserted into the table on Monday or Tuesday, they will be lost forever. The same goes for records modified in this period. This method will not bring back modified records, only the old records that existed on Sunday. If you restore this full database backup, all your changes (intentional and accidental) will be lost and the database will be reverted to the state it had on Sunday. What you have to do is compare the records that were in the table on Sunday to the records on Wednesday, create a synchronization script, and execute it against the Wednesday database. If you have a full database backup followed by differential database backups Let’s say the situation is the same as in the example above, only you create a differential database backup every night. Use the full database backup created on Sunday, and the last differential database backup (created on Tuesday). In this scenario, you will lose only the data inserted and updated after the differential backup created on Tuesday. If you have a full database backup and a chain of transaction log backups This is the SQL Server disaster recovery strategy that provides minimal data loss. With a full chain of transaction logs, you can recover the SQL database to an exact point in time. To provide optimal results, you have to know exactly when the records were deleted, because restoring to a later point will not bring back the records. This method requires restoring the full database backup first. If you have any differential log backup created after the last full database backup, restore the most recent one. Then, restore transaction log backups, one by one, it the order they were created starting with the first created after the restored differential database backup. Now, the table will be in the state before the records were deleted. You have to identify the deleted records, script them and run the script against the original database. Although this method is reliable, it is time-consuming and requires a lot of space on disk. How to easily recover deleted records? The following solution enables you to recover SQL database records even if you have no full or differential database backups and no transaction log backups. To understand how ApexSQL Recover works, I’ll explain what happens when table data is deleted. Table data is stored in data pages. When you delete table records, they are not immediately deleted from the data pages, but marked to be overwritten by new records. Such records are not shown as existing anymore, but ApexSQL Recover can read them and create undo script for them. How long will deleted records stay in the MDF file? It depends on many factors, as time passes it’s less likely that the records will not be overwritten. The more transactions occur after the deletion, the more chances the records will be overwritten and permanently lost. Therefore, it’s recommended to create a copy of the database MDF and LDF files immediately (if you cannot take your database offline until the issue is solved) and run ApexSQL Recover on them. Note that a full database backup will not help here, as the records marked for overwriting are not included in the backup. First, I’ll delete some records from the Person.EmailAddress table in the AdventureWorks database.   I can delete these records in SQL Server Management Studio, or execute a script such as DELETE FROM Person.EmailAddress WHERE BusinessEntityID BETWEEN 70 AND 80 Then, I’ll start ApexSQL Recover and select From DELETE operation in the Recovery tab.   In the Select the database to recover step, first select the SQL Server instance. If it’s not shown in the drop-down list, click the Server icon right to the Server drop-down list and browse for the SQL Server instance, or type the instance name manually. Specify the authentication type and select the database in the Database drop-down list.   In the next step, you’re prompted to add additional data sources. As this can be a tricky step, especially for new users, ApexSQL Recover offers help via the Help me decide option.   The Help me decide option guides you through a series of questions about the database transaction log and advises what files to add. If you know that you have no transaction log backups or detached transaction logs, or the online transaction log file has been truncated after the data was deleted, select No additional transaction logs are available. If you know that you have transaction log backups that contain the delete transactions you want to recover, click Add transaction logs. The online transaction log is listed and selected automatically.   Click Add if to add transaction log backups. It would be best if you have a full transaction log chain, as explained above. The next step for this option is to specify the time range.   Selecting a small time range for the time of deletion will create the recovery script just for the accidentally deleted records. A wide time range might script the records deleted on purpose, and you don’t want that. If needed, you can check the script generated and manually remove such records. After that, for all data sources options, the next step is to select the tables. Be careful here, if you deleted some data from other tables on purpose, and don’t want to recover them, don’t select all tables, as ApexSQL Recover will create the INSERT script for them too.   The next step offers two options: to create a recovery script that will insert the deleted records back into the Person.EmailAddress table, or to create a new database, create the Person.EmailAddress table in it, and insert the deleted records. I’ll select the first one.   The recovery process is completed and 11 records are found and scripted, as expected.   To see the script, click View script. ApexSQL Recover has its own script editor, where you can review, modify, and execute the recovery script. The insert into statements look like: INSERT INTO Person.EmailAddress( BusinessEntityID, EmailAddressID, EmailAddress, rowguid, ModifiedDate) VALUES( 70, 70, N'[email protected]' COLLATE SQL_Latin1_General_CP1_CI_AS, 'd62c5b4e-c91f-403f-b630-7b7e0fda70ce', '20030109 00:00:00.000' ); To execute the script, click Execute in the menu.   If you want to check whether the records are really back, execute SELECT * FROM Person.EmailAddress WHERE BusinessEntityID BETWEEN 70 AND 80 As shown, ApexSQL Recover recovers SQL database data after accidental deletes even without the database backup that contains the deleted data and relevant transaction log backups. ApexSQL Recover reads the deleted data from the database data file, so this method can be used even for databases in the Simple recovery model. Besides recovering SQL database records from a DELETE statement, ApexSQL Recover can help when the records are lost due to a DROP TABLE, or TRUNCATE statement, as well as repair a corrupted MDF file that cannot be attached to as SQL Server instance. You can find more information about how to recover SQL database lost data and repair a SQL Server database on ApexSQL Solution center. There are solutions for various situations when data needs to be recovered. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Backup and Restore, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Introduction – Day 1 of 31

  - by pinaldave

  List of all the Interview Questions and Answers Series blogs Posts covering interview questions and answers always make for interesting reading.  Some people like the subject for their helpful hints and thought provoking subject, and others dislike these posts because they feel it is nothing more than cheating.  I’d like to discuss the pros and cons of a Question and Answer format here. Interview Questions and Answers are Helpful Just like blog posts, books, and articles, interview Question and Answer discussions are learning material.  The popular Dummy’s books or Idiots Guides are not only for “dummies,” but can help everyone relearn the fundamentals.  Question and Answer discussions can serve the same purpose.  You could call this SQL Server Fundamentals or SQL Server 101. I have administrated hundreds of interviews during my career and I have noticed that sometimes an interviewee with several years of experience lacks an understanding of the fundamentals.  These individuals have been in the industry for so long, usually working on a very specific project, that the ABCs of the business have slipped their mind. Or, when a college graduate is looking to get into the industry, he is not expected to have experience since he is just graduated. However, the new grad is expected to have an understanding of fundamentals and theory.  Sometimes after the stress of final exams and graduation, it can be difficult to remember the correct answers to interview questions, though. An interview Question and Answer discussion can be very helpful to both these individuals.  It is simply a way to go back over the building blocks of a topic.  Many times a simple review like this will help “jog” your memory, and all those previously-memorized facts will come flooding back to you.  It is not a way to re-learn a topic, but a way to remind yourself of what you already know. A Question and Answer discussion can also be a way to go over old topics in a more interesting manner.  Especially if you have been working in the industry, or taking lots of classes on the topic, everything you read can sound like a repeat of what you already know.  Going over a topic in a new format can make the material seem fresh and interesting.  And an interested mind will be more engaged and remember more in the end. Interview Questions and Answers are Harmful A common argument against a Question and Answer discussion is that it will give someone a “cheat sheet.” A new guy with relatively little experience can read the interview questions and answers, and then memorize them. When an interviewer asks him the same questions, he will repeat the answers and get the job. Honestly, is he good hire because he memorized the interview questions? Wouldn’t it be better for the interviewer to hire someone with actual experience?  The answer is not as easy as it seems – there are many different factors to be considered. If the interviewer is asking fundamentals-related questions only, he gets the answers he wants to hear, and then hires this first candidate – there is a good chance that he is hiring based on personality rather than experience.  If the interviewer is smart he will ask deeper questions, have more than one person on the interview team, and interview a variety of candidates.  If one interviewee happens to memorize some answers, it usually doesn’t mean he will automatically get the job at the expense of more qualified candidates. Another argument against interview Question and Answers is that it will give candidates a false sense of confidence, and that they will appear more qualified than they are. Well, if that is true, it will not last after the first interview when the candidate is asked difficult questions and he cannot find the answers in the list of interview Questions and Answers.  Besides, confidence is one of the best things to walk into an interview with! In today’s competitive job market, there are often hundreds of candidates applying for the same position.  With so many applicants to choose from, interviewers must make decisions about who to call back and who to hire based on their gut feeling.  One drawback to reading an interview Question and Answer article is that you might sound very boring in your interview – saying the same thing as every single candidate, and parroting answers that sound like someone else wrote them for you – because they did.  However, it is definitely better to go to an interview prepared, just make sure that you give a lot of thought to your answers to make them sound like your own voice.  Remember that you will be hired based on your skills as well as your personality, so don’t think that having all the right answers will make get you hired.  A good interviewee will be prepared, confident, and know how to stand out. My Opinion A list of interview Questions and Answers is really helpful as a refresher or for beginners. To really ace an interview, one needs to have real-world, hands-on experience with SQL Server as well. Interview questions just serve as a starter or easy read for experienced professionals. When I have to learn new technology, I often search online for interview questions and get an idea about the breadth and depth of the technology. Next Action I am going to write about interview Questions and Answers for next 30 days. I have previously written a series of interview questions and answers; now I have re-written them keeping the latest version of SQL Server and current industry progress in mind. If you have faced interesting interview questions or situations, please write to me and I will publish them as a guest post. If you want me to add few more details, leave a comment and I will make sure that I do my best to accommodate. Tomorrow we will start the interview Questions and Answers series, with a few interesting stories, best practices and guest posts. We will have a prize give-away and other awards when the series ends. List of all the Interview Questions and Answers Series blogs Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Regression testing with Selenium GRID

  - by Ben Adderson

  A lot of software teams out there are tasked with supporting and maintaining systems that have grown organically over time, and the web team here at Red Gate is no exception. We're about to embark on our first significant refactoring endeavour for some time, and as such its clearly paramount that the code be tested thoroughly for regressions. Unfortunately we currently find ourselves with a codebase that isn't very testable - the three layers (database, business logic and UI) are currently tightly coupled. This leaves us with the unfortunate problem that, in order to confidently refactor the code, we need unit tests. But in order to write unit tests, we need to refactor the code :S To try and ease the initial pain of decoupling these layers, I've been looking into the idea of using UI automation to provide a sort of system-level regression test suite. The idea being that these tests can help us identify regressions whilst we work towards a more testable codebase, at which point the more traditional combination of unit and integration tests can take over. Ending up with a strong battery of UI tests is also a nice bonus :) Following on from my previous posts (here, here and here) I knew I wanted to use Selenium. I also figured that this would be a good excuse to put my xUnit [Browser] attribute to good use. Pretty quickly, I had a raft of tests that looked like the following (this particular example uses Reflector Pro). In a nut shell the test traverses our shopping cart and, for a particular combination of number of users and months of support, checks that the price calculations all come up with the correct values. [BrowserTheory] [Browser(Browsers.Firefox3_6, "http://www.red-gate.com")] public void Purchase1UserLicenceNoSupport(SeleniumProvider seleniumProvider) {     //Arrange     _browser = seleniumProvider.GetBrowser();     _browser.Open("http://www.red-gate.com/dynamic/shoppingCart/ProductOption.aspx?Product=ReflectorPro");                  //Act     _browser = ShoppingCartHelpers.TraverseShoppingCart(_browser, 1, 0, ".NET Reflector Pro");     //Assert     var priceResult = PriceHelpers.GetNewPurchasePrice(db, "ReflectorPro", 1, 0, Currencies.Euros);         Assert.Equal(priceResult.Price, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl01_Price"));     Assert.Equal(priceResult.Tax, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Tax"));     Assert.Equal(priceResult.Total, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Total")); } These tests are pretty concise, with much of the common code in the TraverseShoppingCart() and GetNewPurchasePrice() methods. The (inevitable) problem arose when it came to execute these tests en masse. Selenium is a very slick tool, but it can't mask the fact that UI automation is very slow. To give you an idea, the set of cases that covers all of our products, for all combinations of users and support, came to 372 tests (for now only considering purchases in dollars). In the world of automated integration tests, that's a very manageable number. For unit tests, it's a trifle. However for UI automation, those 372 tests were taking just over two hours to run. Two hours may not sound like a lot, but those cases only cover one of the three currencies we deal with, and only one of the many different ways our systems can be asked to calculate a price. It was already pretty clear at this point that in order for this approach to be viable, I was going to have to find a way to speed things up. Up to this point I had been using Selenium Remote Control to automate Firefox, as this was the approach I had used previously and it had worked well. Fortunately,  the guys at SeleniumHQ also maintain a tool for executing multiple Selenium RC tests in parallel: Selenium Grid. Selenium Grid uses a central 'hub' to handle allocation of Selenium tests to individual RCs. The Remote Controls simply register themselves with the hub when they start, and then wait to be assigned work. The (for me) really clever part is that, as far as the client driver library is concerned, the grid hub looks exactly the same as a vanilla remote control. To create a new browser session against Selenium RC, the following C# code suffices: new DefaultSelenium("localhost", 4444, "*firefox", "http://www.red-gate.com"); This assumes that the RC is running on the local machine, and is listening on port 4444 (the default). Assuming the hub is running on your local machine, then to create a browser session in Selenium Grid, via the hub rather than directly against the control, the code is exactly the same! Behind the scenes, the hub will take this request and hand it off to one of the registered RCs that provides the "*firefox" execution environment. It will then pass all communications back and forth between the test runner and the remote control transparently. This makes running existing RC tests on a Selenium Grid a piece of cake, as the developers intended. For a more detailed description of exactly how Selenium Grid works, see this page. Once I had a test environment capable of running multiple tests in parallel, I needed a test runner capable of doing the same. Unfortunately, this does not currently exist for xUnit (boo!). MbUnit on the other hand, has the concept of concurrent execution baked right into the framework. So after swapping out my assembly references, and fixing up the resulting mismatches in assertions, my example test now looks like this: [Test] public void Purchase1UserLicenceNoSupport() {    //Arrange    ISelenium browser = BrowserHelpers.GetBrowser();    var db = DbHelpers.GetWebsiteDBDataContext();    browser.Start();    browser.Open("http://www.red-gate.com/dynamic/shoppingCart/ProductOption.aspx?Product=ReflectorPro");                 //Act     browser = ShoppingCartHelpers.TraverseShoppingCart(browser, 1, 0, ".NET Reflector Pro");    var priceResult = PriceHelpers.GetNewPurchasePrice(db, "ReflectorPro", 1, 0, Currencies.Euros);    //Assert     Assert.AreEqual(priceResult.Price, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl01_Price"));     Assert.AreEqual(priceResult.Tax, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Tax"));     Assert.AreEqual(priceResult.Total, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Total")); } This is pretty much the same as the xUnit version. The exceptions are that the attributes have changed,  the //Arrange phase now has to handle setting up the ISelenium object, as the attribute that previously did this has gone away, and the test now sets up its own database connection. Previously I was using a shared database connection, but this approach becomes more complicated when tests are being executed concurrently. To avoid complexity each test has its own connection, which it is responsible for closing. For the sake of readability, I snipped out the code that closes the browser session and the db connection at the end of the test. With all that done, there was only one more step required before the tests would execute concurrently. It is necessary to tell the test runner which tests are eligible to run in parallel, via the [Parallelizable] attribute. This can be done at the test, fixture or assembly level. Since I wanted to run all tests concurrently, I marked mine at the assembly level in the AssemblyInfo.cs using the following: [assembly: DegreeOfParallelism(3)] [assembly: Parallelizable(TestScope.All)] The second attribute marks all tests in the assembly as [Parallelizable], whilst the first tells the test runner how many concurrent threads to use when executing the tests. I set mine to three since I was using 3 RCs in separate VMs. With everything now in place, I fired up the Icarus* test runner that comes with MbUnit. Executing my 372 tests three at a time instead of one at a time reduced the running time from 2 hours 10 minutes, to 55 minutes, that's an improvement of about 58%! I'd like to have seen an improvement of 66%, but I can understand that either inefficiencies in the hub code, my test environment or the test runner code (or some combination of all three most likely) contributes to a slightly diminished improvement. That said, I'd love to hear about any experience you have in upping this efficiency. Ultimately though, it was a saving that was most definitely worth having. It makes regression testing via UI automation a far more plausible prospect. The other obvious point to make is that this approach scales far better than executing tests serially. So if ever we need to improve performance, we just register additional RC's with the hub, and up the DegreeOfParallelism. *This was just my personal preference for a GUI runner. The MbUnit/Gallio installer also provides a command line runner, a TestDriven.net runner, and a Resharper 4.5 runner. For now at least, Resharper 5 isn't supported.

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• Code excavations, wishful invocations, perimeters and domain specific unit test frameworks

  - by RoyOsherove

  One of the talks I did at QCON London was about a subject that I’ve come across fairly recently , when I was building SilverUnit – a “pure” unit test framework for silverlight objects that depend on the silverlight runtime to run. It is the concept of “cogs in the machine” – when your piece of code needs to run inside a host framework or runtime that you have little or no control over for testability related matters. Examples of such cogs and machines can be: your custom control running inside silverlight runtime in the browser your plug-in running inside an IDE your activity running inside a windows workflow your code running inside a java EE bean your code inheriting from a COM+ (enterprise services) component etc.. Not all of these are necessarily testability problems. The main testability problem usually comes when your code actually inherits form something inside the system. For example. one of the biggest problems with testing objects like silverlight controls is the way they depend on the silverlight runtime – they don’t implement some silverlight interface, they don’t just call external static methods against the framework runtime that surrounds them – they actually inherit parts of the framework: they all inherit (in this case) from the silverlight DependencyObject Wrapping it up? An inheritance dependency is uniquely challenging to bring under test, because “classic” methods such as wrapping the object under test with a framework wrapper will not work, and the only way to do manually is to create parallel testable objects that get delegated with all the possible actions from the dependencies.    In silverlight’s case, that would mean creating your own custom logic class that would be called directly from controls that inherit from silverlight, and would be tested independently of these controls. The pro side is that you get the benefit of understanding the “contract” and the “roles” your system plays against your logic, but unfortunately, more often than not, it can be very tedious to create, and may sometimes feel unnecessary or like code duplication. About perimeters A perimeter is that invisible line that your draw around your pieces of logic during a test, that separate the code under test from any dependencies that it uses. Most of the time, a test perimeter around an object will be the list of seams (dependencies that can be replaced such as interfaces, virtual methods etc.) that are actually replaced for that test or for all the tests. Role based perimeters In the case of creating a wrapper around an object – one really creates a “role based” perimeter around the logic that is being tested – that wrapper takes on roles that are required by the code under test, and also communicates with the host system to implement those roles and provide any inputs to the logic under test. in the image below – we have the code we want to test represented as a star. No perimeter is drawn yet (we haven’t wrapped it up in anything yet). in the image below is what happens when you wrap your logic with a role based wrapper – you get a role based perimeter anywhere your code interacts with the system: There’s another way to bring that code under test – using isolation frameworks like typemock, rhino mocks and MOQ (but if your code inherits from the system, Typemock might be the only way to isolate the code from the system interaction.   Ad-Hoc Isolation perimeters the image below shows what I call ad-hoc perimeter that might be vastly different between different tests: This perimeter’s surface is much smaller, because for that specific test, that is all the “change” that is required to the host system behavior.   The third way of isolating the code from the host system is the main “meat” of this post: Subterranean perimeters Subterranean perimeters are Deep rooted perimeters  - “always on” seams that that can lie very deep in the heart of the host system where they are fully invisible even to the test itself, not just to the code under test. Because they lie deep inside a system you can’t control, the only way I’ve found to control them is with runtime (not compile time) interception of method calls on the system. One way to get such abilities is by using Aspect oriented frameworks – for example, in SilverUnit, I’ve used the CThru AOP framework based on Typemock hooks and CLR profilers to intercept such system level method calls and effectively turn them into seams that lie deep down at the heart of the silverlight runtime. the image below depicts an example of what such a perimeter could look like: As you can see, the actual seams can be very far away form the actual code under test, and as you’ll discover, that’s actually a very good thing. Here is only a partial list of examples of such deep rooted seams : disabling the constructor of a base class five levels below the code under test (this.base.base.base.base) faking static methods of a type that’s being called several levels down the stack: method x() calls y() calls z() calls SomeType.StaticMethod()  Replacing an async mechanism with a synchronous one (replacing all timers with your own timer behavior that always Ticks immediately upon calls to “start()” on the same caller thread for example) Replacing event mechanisms with your own event mechanism (to allow “firing” system events) Changing the way the system saves information with your own saving behavior (in silverunit, I replaced all Dependency Property set and get with calls to an in memory value store instead of using the one built into silverlight which threw exceptions without a browser) several questions could jump in: How do you know what to fake? (how do you discover the perimeter?) How do you fake it? Wouldn’t this be problematic  - to fake something you don’t own? it might change in the future How do you discover the perimeter to fake? To discover a perimeter all you have to do is start with a wishful invocation. a wishful invocation is the act of trying to invoke a method (or even just create an instance ) of an object using “regular” test code. You invoke the thing that you’d like to do in a real unit test, to see what happens: Can I even create an instance of this object without getting an exception? Can I invoke this method on that instance without getting an exception? Can I verify that some call into the system happened? You make the invocation, get an exception (because there is a dependency) and look at the stack trace. choose a location in the stack trace and disable it. Then try the invocation again. if you don’t get an exception the perimeter is good for that invocation, so you can move to trying out other methods on that object. in a future post I will show the process using CThru, and how you end up with something close to a domain specific test framework after you’re done creating the perimeter you need.

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• RequestValidation Changes in ASP.NET 4.0

  - by Rick Strahl

  There’s been a change in the way the ValidateRequest attribute on WebForms works in ASP.NET 4.0. I noticed this today while updating a post on my WebLog all of which contain raw HTML and so all pretty much trigger request validation. I recently upgraded this app from ASP.NET 2.0 to 4.0 and it’s now failing to update posts. At first this was difficult to track down because of custom error handling in my app – the custom error handler traps the exception and logs it with only basic error information so the full detail of the error was initially hidden. After some more experimentation in development mode the error that occurs is the typical ASP.NET validate request error (‘A potentially dangerous Request.Form value was detetected…’) which looks like this in ASP.NET 4.0: At first when I got this I was real perplexed as I didn’t read the entire error message and because my page does have: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="NewEntry.aspx.cs" Inherits="Westwind.WebLog.NewEntry" MasterPageFile="~/App_Templates/Standard/AdminMaster.master" ValidateRequest="false" EnableEventValidation="false" EnableViewState="false" %> WTF? ValidateRequest would seem like it should be enough, but alas in ASP.NET 4.0 apparently that setting alone is no longer enough. Reading the fine print in the error explains that you need to explicitly set the requestValidationMode for the application back to V2.0 in web.config: <httpRuntime executionTimeout="300" requestValidationMode="2.0" /> Kudos for the ASP.NET team for putting up a nice error message that tells me how to fix this problem, but excuse me why the heck would you change this behavior to require an explicit override to an optional and by default disabled page level switch? You’ve just made a relatively simple fix to a solution a nasty morass of hard to discover configuration settings??? The original way this worked was perfectly discoverable via attributes in the page. Now you can set this setting in the page and get completely unexpected behavior and you are required to set what effectively amounts to a backwards compatibility flag in the configuration file. It turns out the real reason for the .config flag is that the request validation behavior has moved from WebForms pipeline down into the entire ASP.NET/IIS request pipeline and is now applied against all requests. Here’s what the breaking changes page from Microsoft says about it: The request validation feature in ASP.NET provides a certain level of default protection against cross-site scripting (XSS) attacks. In previous versions of ASP.NET, request validation was enabled by default. However, it applied only to ASP.NET pages (.aspx files and their class files) and only when those pages were executing. In ASP.NET 4, by default, request validation is enabled for all requests, because it is enabled before the BeginRequest phase of an HTTP request. As a result, request validation applies to requests for all ASP.NET resources, not just .aspx page requests. This includes requests such as Web service calls and custom HTTP handlers. Request validation is also active when custom HTTP modules are reading the contents of an HTTP request. As a result, request validation errors might now occur for requests that previously did not trigger errors. To revert to the behavior of the ASP.NET 2.0 request validation feature, add the following setting in the Web.config file: <httpRuntime requestValidationMode="2.0" /> However, we recommend that you analyze any request validation errors to determine whether existing handlers, modules, or other custom code accesses potentially unsafe HTTP inputs that could be XSS attack vectors. Ok, so ValidateRequest of the form still works as it always has but it’s actually the ASP.NET Event Pipeline, not WebForms that’s throwing the above exception as request validation is applied to every request that hits the pipeline. Creating the runtime override removes the HttpRuntime checking and restores the WebForms only behavior. That fixes my immediate problem but still leaves me wondering especially given the vague wording of the above explanation. One thing that’s missing in the description is above is one important detail: The request validation is applied only to application/x-www-form-urlencoded POST content not to all inbound POST data. When I first read this this freaked me out because it sounds like literally ANY request hitting the pipeline is affected. To make sure this is not really so I created a quick handler: public class Handler1 : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World <hr>" + context.Request.Form.ToString()); } public bool IsReusable { get { return false; } } } and called it with Fiddler by posting some XML to the handler using a default form-urlencoded POST content type: and sure enough – hitting the handler also causes the request validation error and 500 server response. Changing the content type to text/xml effectively fixes the problem however, bypassing the request validation filter so Web Services/AJAX handlers and custom modules/handlers that implement custom protocols aren’t affected as long as they work with special input content types. It also looks that multipart encoding does not trigger event validation of the runtime either so this request also works fine: POST http://rasnote/weblog/handler1.ashx HTTP/1.1 Content-Type: multipart/form-data; boundary=------7cf2a327f01ae User-Agent: West Wind Internet Protocols 5.53 Host: rasnote Content-Length: 40 Pragma: no-cache <xml>asdasd</xml>--------7cf2a327f01ae *That* probably should trigger event validation – since it is a potential HTML form submission, but it doesn’t. New Runtime Feature, Global Scope Only? Ok, so request validation is now a runtime feature but sadly it’s a feature that’s scoped to the ASP.NET Runtime – effective scope to the entire running application/app domain. You can still manually force validation using Request.ValidateInput() which gives you the option to do this in code, but that realistically will only work with the requestValidationMode set to V2.0 as well since the 4.0 mode auto-fires before code ever gets a chance to intercept the call. Given all that, the new setting in ASP.NET 4.0 seems to limit options and makes things more difficult and less flexible. Of course Microsoft gets to say ASP.NET is more secure by default because of it but what good is that if you have to turn off this flag the very first time you need to allow one single request that bypasses request validation??? This is really shortsighted design… <sigh>© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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• PeopleSoft Upgrades, Fusion, & BI for Leading European PeopleSoft Applications Customers

  - by Mark Rosenberg

  With so many industry-leading services firms around the globe managing their businesses with PeopleSoft, it’s always an adventure setting up times and meetings for us to keep in touch with them, especially those outside of North America who often do not get to join us at Oracle OpenWorld. Fortunately, during the first two weeks of May, Nigel Woodland (Oracle’s Service Industries Director for the EMEA region) and I successfully blocked off our calendars to visit seven different customers spanning four countries in Western Europe. We met executives and leaders at four Staffing industry firms, two Professional Services firms that engage in consulting and auditing, and a Financial Services firm. As we shared the latest information regarding product capabilities and plans, we also gained valuable insight into the hot technology topics facing these businesses. What we heard was both informative and inspiring, and I suspect other Oracle PeopleSoft applications customers can benefit from one or more of the following observations from our trip. Great IT Plans Get Executed When You Respect the Users Each of our visits followed roughly the same pattern. After introductions, Nigel outlined Oracle’s product and technology strategy, including a discussion of how we at Oracle invest in each layer of the “technology stack” to provide customers with unprecedented business management capabilities and choice. Then, I provided the specifics of the PeopleSoft product line’s investment strategy, detailing the dramatic number of rich usability and functionality enhancements added to release 9.1 since its general availability in 2009 and the game-changing capabilities slated for 9.2. What was most exciting about each of these discussions was that shortly after my talking about what customers can do with release 9.1 right now to drive up user productivity and satisfaction, I saw the wheels turning in the minds of our audiences. Business analyst and end user-configurable tools and technologies, such as WorkCenters and the Related Action Framework, that provide the ability to tailor a “central command center” to the exact needs of each recruiter, biller, and every other role in the organization were exactly what each of our customers had been looking for. Every one of our audiences agreed that these tools which demonstrate a respect for the user would finally help IT pole vault over the wall of resistance that users had often raised in the past. With these new user-focused capabilities, IT is positioned to definitively partner with the business, instead of drag the business along, to unlock the value of their investment in PeopleSoft. This topic of respecting the user emerged during our very first visit, which was at Vital Services Group at their Head Office “The Mill” in Manchester, England. (If you are a student of architecture and are ever in Manchester, you should stop in to see this amazingly renovated old mill building.) I had just finished explaining our PeopleSoft 9.2 roadmap, and Mike Code, PeopleSoft Systems Manager for this innovative staffing company, said, “Mark, the new features you’ve shown us in 9.1/9.2 are very relevant to our business. As we forge ahead with the 9.1 upgrade, the ability to configure a targeted user interface with WorkCenters, Related Actions, Pivot Grids, and Alerts will enable us to satisfy the business that this upgrade is for them and will deliver tangible benefits. In fact, you’ve highlighted that we need to start talking to the business to keep up the momentum to start reviewing the 9.2 upgrade after we get to 9.1, because as much as 9.1 and PeopleTools 8.52 offers, what you’ve shown us for 9.2 is what we’ve envisioned was ultimately possible with our investment in PeopleSoft applications.” We also received valuable feedback about our investment for the Staffing industry when we visited with Hans Wanders, CIO of Randstad (the second largest Staffing company in the world) in the Netherlands. After our visit, Hans noted, “It was very interesting to see how the PeopleSoft applications have developed. I was truly impressed by many of the new developments.” Hans and Mike, sincere thanks for the validation that our team’s hard work and dedication to “respecting the users” is worth the effort! Co-existence of PeopleSoft and Fusion Applications Just Makes Sense As a “product person,” one of the most rewarding things about visiting customers is that they actually want to talk to me. Sometimes, they want to discuss a product area that we need to enhance; other times, they are interested in learning how to extract more value from their applications; and still others, they want to tell me how they are using the applications to drive real value for the business. During this trip, I was very pleased to hear that several of our customers not only thought the co-existence of Fusion applications alongside PeopleSoft applications made sense in theory, but also that they were aggressively looking at how to deploy one or more Fusion applications alongside their PeopleSoft HCM and FSCM applications. The most common deployment plan in the works by three of the organizations is to upgrade to PeopleSoft 9.1 or 9.2, and then adopt one of the new Fusion HCM applications, such as Fusion Performance Management or the full suite of  Fusion Talent Management. For example, during an applications upgrade planning discussion with the staffing company Hays plc., Mark Thomas, who is Hays’ UK IT Director, commented, “We are very excited about where we can go with the latest versions of the PeopleSoft applications in conjunction with Fusion Talent Management.” Needless to say, this news was very encouraging, because it reiterated that our applications investment strategy makes good business sense for our customers. Next Generation Business Intelligence Is the Key to the Future The third, and perhaps most exciting, lesson I learned during this journey is that our audiences already know that the latest generation of Business Intelligence technologies will be the “secret sauce” for organizations to transform business in radical ways. While a number of the organizations we visited on the trip have deployed or are deploying Oracle Business Intelligence Enterprise Edition and the associated analytics applications to provide dashboards of easy-to-understand, user-configurable metrics that help optimize business performance according to current operating procedures, what’s most exciting to them is being able to use Business Intelligence to change the way an organization does business, grows revenue, and makes a profit. In particular, several executives we met asked whether we can help them minimize the need to have perfectly structured data and at the same time generate analytics that improve order fulfillment decision-making. To them, the path to future growth lies in having the ability to analyze unstructured data rapidly and intuitively and leveraging technology’s ability to detect patterns that a human cannot reasonably be expected to see. For illustrative purposes, here is a good example of a business problem where analyzing a combination of structured and unstructured data can produce better results. If you have a resource manager trying to decide which person would be the best fit for an assignment in terms of ensuring (a) client satisfaction, (b) the individual’s satisfaction with the work, (c) least travel distance, and (d) highest margin, you traditionally compare resource qualifications to assignment needs, calculate margins on past work with the client, and measure distances. To perform these comparisons, you are likely to need the organization to have profiles setup, people ranked against profiles, margin targets setup, margins measured, distances setup, distances measured, and more. As you can imagine, this requires organizations to plan and implement data setup, capture, and quality management initiatives to ensure that dependable information is available to support resourcing analysis and decisions. In the fast-paced, tight-budget world in which most organizations operate today, the effort and discipline required to maintain high-quality, structured data like those described in the above example are certainly not desirable and in some cases are not feasible. You can imagine how intrigued our audiences were when I informed them that we are ready to help them analyze volumes of unstructured data, detect trends, and produce recommendations. Our discussions delved into examples of how the firms could leverage Oracle’s Secure Enterprise Search and Endeca technologies to keyword search against, compare, and learn from unstructured resource and assignment data. We also considered examples of how they could employ Oracle Real-Time Decisions to generate statistically significant recommendations based on similar resourcing scenarios that have produced the desired satisfaction and profit margin results. --- Although I had almost no time for sight-seeing during this trip to Europe, I have to say that it may have been one of the most energizing and engaging trips of my career. Showing these dedicated customers how they can give every user a uniquely tailored set of tools and address business problems in ways that have to date been impossible made the journey across the Atlantic more than worth it. If any of these three topics intrigue you, I’d recommend you contact your Oracle applications representative to arrange for more detailed discussions with the appropriate members of our organization.

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• Setup and Use SpecFlow BDD with DevExpress XAF

  - by Patrick Liekhus

  Let’s get started with using the SpecFlow BDD syntax for writing tests with the DevExpress XAF EasyTest scripting syntax.  In order for this to work you will need to download and install the prerequisites listed below.  Once they are installed follow the steps outlined below and enjoy. Prerequisites Install the following items: DevExpress eXpress Application Framework (XAF) found here SpecFlow found here Liekhus BDD/XAF Testing library found here Assumptions I am going to assume at this point that you have created your XAF application and have your Module, Win.Module and Win ready for usage.  You should have also set any attributes and/or settings as you see fit. Setup So where to start. Create a new testing project within your solution. I typically call this with a similar naming convention as used by XAF, my project name .FunctionalTests (i.e. AlbumManager.FunctionalTests). Add the following references to your project.  It should look like the reference list below. DevExpress.Data.v11.x DevExpress.Persistent.Base.v11.x DevExpress.Persistent.BaseImpl.v11.x DevExpress.Xpo.v11.2 Liekhus.Testing.BDD.Core Liekhus.Testing.BDD.DevExpress TechTalk.SpecFlow TestExecutor.v11.x (found in %Program Files%\DevExpress 2011.x\eXpressApp Framework\Tools\EasyTest Right click the TestExecutor reference and set the “Copy Local” setting to True.  This forces the TestExecutor executable to be available in the bin directory which is where the EasyTest script will be executed further down in the process. Add an Application Configuration File (app.config) to your test application.  You will need to make a few modifications to have SpecFlow generate Microsoft style unit tests.  First add the section handler for SpecFlow and then set your choice of testing framework.  I prefer MS Tests for my projects. Add the EasyTest configuration file to your project.  Add a new XML file and call it Config.xml. Open the properties window for the Config.xml file and set the “Copy to Ouput Directory” to “Copy Always”. You will setup the Config file according to the specifications of the EasyTest library my mapping to your executable and other settings.  You can find the details for the configuration of EasyTest here.  My file looks like this Create a new folder in your test project called “StepDefinitions”.  Add a new SpecFlow Step Definition file item under the StepDefinitions folder.  I typically call this class StepDefinition.cs. Have your step definition inherit from the Liekhus.Testing.BDD.DevExpress.StepDefinition class.  This will give you the default behaviors for your test in the next section. OK.  Now that we have done this series of steps, we will work on simplifying this.  This is an early preview of this new project and is not fully ready for consumption.  If you would like to experiment with it, please feel free.  Our goals are to make this a installable project on it’s own with it’s own project templates and default settings.  This will be coming in later versions.  Currently this project is in Alpha release. Let’s write our first test Remove the basic test that is created for you. We will not use the default test but rather create our own SpecFlow “Feature” files. Add a new item to your project and select the SpecFlow Feature file under C#. Name your feature file as you do your class files after the test they are performing. Writing a feature file uses the Cucumber syntax of Given… When… Then.  Think of it in these terms.  Givens are the pre-conditions for the test.  The Whens are the actual steps for the test being performed.  The Thens are the verification steps that confirm your test either passed or failed.  All of these steps are generated into a an EasyTest format and executed against your XAF project.  You can find more on the Cucumber syntax by using the Secret Ninja Cucumber Scrolls.  This document has several good styles of tests, plus you can get your fill of Chuck Norris vs Ninjas.  Pretty humorous document but full of great content. My first test is going to test the entry of a new Album into the application and is outlined below. The Feature section at the top is more for your documentation purposes.  Try to be descriptive of the test so that it makes sense to the next person behind you.  The Scenario outline is described in the Ninja Scrolls, but think of it as test template.  You can write one test outline and have multiple datasets (Scenarios) executed against that test.  Here are the steps of my test and their descriptions Given I am starting a new test – tells our test to create a new EasyTest file And (Given) the application is open – tells EasyTest to open our application defined in the Config.xml When I am at the “Albums” screen – tells XAF to navigate to the Albums list view And (When) I click the “New:Album” button – tells XAF to click the New Album button on the ribbon And (When) I enter the following information – tells XAF to find the field on the screen and put the value in that field And (When) I click the “Save and Close” button – tells XAF to click the “Save and Close” button on the detail window Then I verify results as “user” – tells the testing framework to execute the EasyTest as your configured user Once you compile and prepare your tests you should see the following in your Test View.  For each of your CreateNewAlbum lines in your scenarios, you will see a new test ready to execute. From here you will use your testing framework of choice to execute the test.  This in turn will execute the EasyTest framework to call back into your XAF application and test your business application. Again, please remember that this is an early preview and we are still working out the details.  Please let us know if you have any comments/questions/concerns. Thanks and happy testing.

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• The APEX of Business Value...or...the Business Value of APEX? Oracle Cloud Takes Oracle APEX to New Heights!

  - by Gene Eun

  The attraction of Oracle Application Express (APEX) has increased tremendously with the recent launch of the Oracle Cloud. APEX already supported departmental development and deployment of business applications with minimal involvement from the IT department. Positioned as the ideal replacement for MS Access, APEX probably has managed better to capture the eye of developers and was used for enterprise application development at least as much as for the kind of tactical applications that Oracle strategically positioned it for. With APEX as PaaS from the Oracle Cloud, a leap is made to a much higher level of business value. Now the IT department is not even needed to make infrastructure available with a database running  on it. All the business needs is a credit card. And the business application that is developed, managed and used from the cloud through a standard browser can now just as easily be accessed by users from around the world as by users from the business department itself. As a bonus – the development of the APEX application is also done in the cloud – with no special demands on the location or the enterprise access privileges of the developers. To sum it up: APEX from Oracle Cloud Database Service get the development environment up and running in minutes no involvement from the internal IT department required (not for infrastructure, platform, or development) superior availability and scalability is offered by Oracle users from anywhere in the world can be invited to access the application developers from anywhere in the world can participate in creating and maintaining the application In addition: because the Oracle Cloud platform is the same as the on-premise platform, you can still decide to move the APEX application between the cloud and the local environment – and back again. The REST-ful services that are available through APEX allow programmatic interaction with the database under the APEX application. That means that this database can be synchronized with on premise databases or data stores in (other) clouds. Through the Oracle Cloud Messaging Service, the APEX application can easily enter into asynchronous conversations with other APEX applications, Fusion Middleware applications (ADF, SOA, BPM) and any other type of REST-enabled application. In my opinion, now, for the first time perhaps, APEX offers the attraction to the business that has been suggested before: because of the cloud, all the business needs is  a credit card (a budget of $175 per month), an internet-connection and a browser. Not like before, with a PC hidden under a desk or a database running somewhere in the data center. No matter how unattended: equipment is needed, power is consumed, the database needs to be kept running and if Oracle Database XE does not suffice, software licenses are required as well. And this set up always has a security challenge associated with it. The cloud fee for the Oracle Cloud Database Service includes infrastructure, power, licenses, availability, platform upgrades, a collection of reusable application components and the development and runtime environments containing the APEX platform. Of course this not only means that business departments can move quickly without having to convince their IT colleagues to move along – it also means that small organizations that do not even have IT colleagues can do the same. Getting tailored applications or applications up and running to get in touch with users and customers all over the world is now within easy reach for small outfits – without any investment. My misunderstanding For a long time, I was under the impression that the essence of APEX was that the business could create applications themselves – meaning that business ‘people’ would actually go into APEX to create the application. To me APEX was too much of a developers’ tool to see that happen – apart from the odd business analyst who missed his or her calling as an IT developer. Having looked at various other cloud based development offerings – including Force.com, Mendix, WaveMaker, WorkXpress, OrangeScape, Caspio and Cordys- I have come to realize my mistake. All these platforms are positioned for 'the business' but require a fair amount of coding and technical expertise. However, they make the business happy nevertheless, because they allow the  business to completely circumvent the IT department. That is the essence. Not having to go through the red tape, not having to wait for IT staff who (justifiably) need weeks or months to provide an environment, not having to deal with administrators (again, justifiably) refusing to take on that 'strange environment'. Being able to think of an initiative and turn into action right away. The business does not have to build the application - it can easily hire some external developers or even that nerdy boy next door. They can get started, get an application up and running and invite users in – especially external users such as customers. They will worry later about upgrades and life cycle management and integration. To get applications up and running quickly and start turning ideas into action and results rightaway. That is the key selling point for all these cloud offerings, including APEX from the Cloud. And it is a compelling story. For APEX probably even more so than for the others. While I consider APEX a somewhat proprietary framework compared with ‘regular’ Java/JEE web development (or even .NET and PHP  development), it is still far more open than most cloud environments. APEX is SQL and PL/SQL based – nothing special about those languages – and can run just as easily on site as in the cloud. It has been around since 2004 (that is not including several predecessors that fed straight into APEX) so it can be considered pretty mature. Oracle as a company seems pretty stable – so investments in its technology are bound to last for some time to come. By the way: neither APEX nor the other Cloud DevaaS offerings are targeted at creating applications with enormous life times. They fit into a trend of agile development and rapid life cycle management, with fairly light weight user interfaces that quickly adapt to taste, technology trends and functional requirements and that are easily replaced. APEX and ADF – a match made in heaven?! (or at least in the sky) Note that using APEX only for cloud based database with REST-ful Services is also a perfectly viable scenario: any UI – mobile or browser based – capable of consuming REST-ful services can be created against such a business tier. Creating an ADF Mobile application for example that runs aginst REST-ful services is a best practice for mobile development. Such REST-ful services can be consumed from any service provider – including the Cloud based APEX powered REST-ful services running against the Oracle Cloud Database Service! The ADF Mobile architecture overview can easily be morphed to fit the APEX services in – allowing for a cloud based mobile app: Want to learn more about Oracle Database Cloud Service or Oracle Cloud, just visit cloud.oracle.com  or oracle.com/cloud. Repost of a blog entry by Rick Greenwald, Director of Product Management, Oracle Database Cloud Service.

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