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• Commit in SQL

  - by PRajkumar

  SQL Transaction Control Language Commands (TCL)                                           (COMMIT) Commit Transaction As a SQL language we use transaction control language very frequently. Committing a transaction means making permanent the changes performed by the SQL statements within the transaction. A transaction is a sequence of SQL statements that Oracle Database treats as a single unit. This statement also erases all save points in the transaction and releases transaction locks. Oracle Database issues an implicit COMMIT before and after any data definition language (DDL) statement. Oracle recommends that you explicitly end every transaction in your application programs with a COMMIT or ROLLBACK statement, including the last transaction, before disconnecting from Oracle Database. If you do not explicitly commit the transaction and the program terminates abnormally, then the last uncommitted transaction is automatically rolled back.   Until you commit a transaction: ·         You can see any changes you have made during the transaction by querying the modified tables, but other users cannot see the changes. After you commit the transaction, the changes are visible to other users' statements that execute after the commit ·         You can roll back (undo) any changes made during the transaction with the ROLLBACK statement   Note: Most of the people think that when we type commit data or changes of what you have made has been written to data files, but this is wrong when you type commit it means that you are saying that your job has been completed and respective verification will be done by oracle engine that means it checks whether your transaction achieved consistency when it finds ok it sends a commit message to the user from log buffer but not from data buffer, so after writing data in log buffer it insists data buffer to write data in to data files, this is how it works.   Before a transaction that modifies data is committed, the following has occurred: ·         Oracle has generated undo information. The undo information contains the old data values changed by the SQL statements of the transaction ·         Oracle has generated redo log entries in the redo log buffer of the System Global Area (SGA). The redo log record contains the change to the data block and the change to the rollback block. These changes may go to disk before a transaction is committed ·         The changes have been made to the database buffers of the SGA. These changes may go to disk before a transaction is committed   Note:   The data changes for a committed transaction, stored in the database buffers of the SGA, are not necessarily written immediately to the data files by the database writer (DBWn) background process. This writing takes place when it is most efficient for the database to do so. It can happen before the transaction commits or, alternatively, it can happen some times after the transaction commits.   When a transaction is committed, the following occurs: 1.      The internal transaction table for the associated undo table space records that the transaction has committed, and the corresponding unique system change number (SCN) of the transaction is assigned and recorded in the table 2.      The log writer process (LGWR) writes redo log entries in the SGA's redo log buffers to the redo log file. It also writes the transaction's SCN to the redo log file. This atomic event constitutes the commit of the transaction 3.      Oracle releases locks held on rows and tables 4.      Oracle marks the transaction complete   Note:   The default behavior is for LGWR to write redo to the online redo log files synchronously and for transactions to wait for the redo to go to disk before returning a commit to the user. However, for lower transaction commit latency application developers can specify that redo be written asynchronously and that transaction do not need to wait for the redo to be on disk.   The syntax of Commit Statement is   COMMIT [WORK] [COMMENT ‘your comment’]; ·         WORK is optional. The WORK keyword is supported for compliance with standard SQL. The statements COMMIT and COMMIT WORK are equivalent. Examples Committing an Insert INSERT INTO table_name VALUES (val1, val2); COMMIT WORK; ·         COMMENT Comment is also optional. This clause is supported for backward compatibility. Oracle recommends that you used named transactions instead of commit comments. Specify a comment to be associated with the current transaction. The 'text' is a quoted literal of up to 255 bytes that Oracle Database stores in the data dictionary view DBA_2PC_PENDING along with the transaction ID if a distributed transaction becomes in doubt. This comment can help you diagnose the failure of a distributed transaction. Examples The following statement commits the current transaction and associates a comment with it: COMMIT     COMMENT 'In-doubt transaction Code 36, Call (415) 555-2637'; ·         WRITE Clause Use this clause to specify the priority with which the redo information generated by the commit operation is written to the redo log. This clause can improve performance by reducing latency, thus eliminating the wait for an I/O to the redo log. Use this clause to improve response time in environments with stringent response time requirements where the following conditions apply: The volume of update transactions is large, requiring that the redo log be written to disk frequently. The application can tolerate the loss of an asynchronously committed transaction. The latency contributed by waiting for the redo log write to occur contributes significantly to overall response time. You can specify the WAIT | NOWAIT and IMMEDIATE | BATCH clauses in any order. Examples To commit the same insert operation and instruct the database to buffer the change to the redo log, without initiating disk I/O, use the following COMMIT statement: COMMIT WRITE BATCH; Note: If you omit this clause, then the behavior of the commit operation is controlled by the COMMIT_WRITE initialization parameter, if it has been set. The default value of the parameter is the same as the default for this clause. Therefore, if the parameter has not been set and you omit this clause, then commit records are written to disk before control is returned to the user. WAIT | NOWAIT Use these clauses to specify when control returns to the user. The WAIT parameter ensures that the commit will return only after the corresponding redo is persistent in the online redo log. Whether in BATCH or IMMEDIATE mode, when the client receives a successful return from this COMMIT statement, the transaction has been committed to durable media. A crash occurring after a successful write to the log can prevent the success message from returning to the client. In this case the client cannot tell whether or not the transaction committed. The NOWAIT parameter causes the commit to return to the client whether or not the write to the redo log has completed. This behavior can increase transaction throughput. With the WAIT parameter, if the commit message is received, then you can be sure that no data has been lost. Caution: With NOWAIT, a crash occurring after the commit message is received, but before the redo log record(s) are written, can falsely indicate to a transaction that its changes are persistent. If you omit this clause, then the transaction commits with the WAIT behavior. IMMEDIATE | BATCH Use these clauses to specify when the redo is written to the log. The IMMEDIATE parameter causes the log writer process (LGWR) to write the transaction's redo information to the log. This operation option forces a disk I/O, so it can reduce transaction throughput. The BATCH parameter causes the redo to be buffered to the redo log, along with other concurrently executing transactions. When sufficient redo information is collected, a disk write of the redo log is initiated. This behavior is called "group commit", as redo for multiple transactions is written to the log in a single I/O operation. If you omit this clause, then the transaction commits with the IMMEDIATE behavior. ·         FORCE Clause Use this clause to manually commit an in-doubt distributed transaction or a corrupt transaction. ·         In a distributed database system, the FORCE string [, integer] clause lets you manually commit an in-doubt distributed transaction. The transaction is identified by the 'string' containing its local or global transaction ID. To find the IDs of such transactions, query the data dictionary view DBA_2PC_PENDING. You can use integer to specifically assign the transaction a system change number (SCN). If you omit integer, then the transaction is committed using the current SCN. ·         The FORCE CORRUPT_XID 'string' clause lets you manually commit a single corrupt transaction, where string is the ID of the corrupt transaction. Query the V$CORRUPT_XID_LIST data dictionary view to find the transaction IDs of corrupt transactions. You must have DBA privileges to view the V$CORRUPT_XID_LIST and to specify this clause. ·         Specify FORCE CORRUPT_XID_ALL to manually commit all corrupt transactions. You must have DBA privileges to specify this clause. Examples Forcing an in doubt transaction. Example The following statement manually commits a hypothetical in-doubt distributed transaction. Query the V$CORRUPT_XID_LIST data dictionary view to find the transaction IDs of corrupt transactions. You must have DBA privileges to view the V$CORRUPT_XID_LIST and to issue this statement. COMMIT FORCE '22.57.53';

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• CLR via C# 3rd Edition is out

  - by Abhijeet Patel

  Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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• Auto DOP and Concurrency

  - by jean-pierre.dijcks

  After spending some time in the cloud, I figured it is time to come down to earth and start discussing some of the new Auto DOP features some more. As Database Machines (the v2 machine runs Oracle Database 11.2) are effectively selling like hotcakes, it makes some sense to talk about the new parallel features in more detail. For basic understanding make sure you have read the initial post. The focus there is on Auto DOP and queuing, which is to some extend the focus here. But now I want to discuss the concurrency a little and explain some of the relevant parameters and their impact, specifically in a situation with concurrency on the system. The goal of Auto DOP The idea behind calculating the Automatic Degree of Parallelism is to find the highest possible DOP (ideal DOP) that still scales. In other words, if we were to increase the DOP even more  above a certain DOP we would see a tailing off of the performance curve and the resource cost / performance would become less optimal. Therefore the ideal DOP is the best resource/performance point for that statement. The goal of Queuing On a normal production system we should see statements running concurrently. On a Database Machine we typically see high concurrency rates, so we need to find a way to deal with both high DOP’s and high concurrency. Queuing is intended to make sure we Don’t throttle down a DOP because other statements are running on the system Stay within the physical limits of a system’s processing power Instead of making statements go at a lower DOP we queue them to make sure they will get all the resources they want to run efficiently without trashing the system. The theory – and hopefully – practice is that by giving a statement the optimal DOP the sum of all statements runs faster with queuing than without queuing. Increasing the Number of Potential Parallel Statements To determine how many statements we will consider running in parallel a single parameter should be looked at. That parameter is called PARALLEL_MIN_TIME_THRESHOLD. The default value is set to 10 seconds. So far there is nothing new here…, but do realize that anything serial (e.g. that stays under the threshold) goes straight into processing as is not considered in the rest of this post. Now, if you have a system where you have two groups of queries, serial short running and potentially parallel long running ones, you may want to worry only about the long running ones with this parallel statement threshold. As an example, lets assume the short running stuff runs on average between 1 and 15 seconds in serial (and the business is quite happy with that). The long running stuff is in the realm of 1 – 5 minutes. It might be a good choice to set the threshold to somewhere north of 30 seconds. That way the short running queries all run serial as they do today (if it ain’t broken, don’t fix it) and allows the long running ones to be evaluated for (higher degrees of) parallelism. This makes sense because the longer running ones are (at least in theory) more interesting to unleash a parallel processing model on and the benefits of running these in parallel are much more significant (again, that is mostly the case). Setting a Maximum DOP for a Statement Now that you know how to control how many of your statements are considered to run in parallel, lets talk about the specific degree of any given statement that will be evaluated. As the initial post describes this is controlled by PARALLEL_DEGREE_LIMIT. This parameter controls the degree on the entire cluster and by default it is CPU (meaning it equals Default DOP). For the sake of an example, let’s say our Default DOP is 32. Looking at our 5 minute queries from the previous paragraph, the limit to 32 means that none of the statements that are evaluated for Auto DOP ever runs at more than DOP of 32. Concurrently Running a High DOP A basic assumption about running high DOP statements at high concurrency is that you at some point in time (and this is true on any parallel processing platform!) will run into a resource limitation. And yes, you can then buy more hardware (e.g. expand the Database Machine in Oracle’s case), but that is not the point of this post… The goal is to find a balance between the highest possible DOP for each statement and the number of statements running concurrently, but with an emphasis on running each statement at that highest efficiency DOP. The PARALLEL_SERVER_TARGET parameter is the all important concurrency slider here. Setting this parameter to a higher number means more statements get to run at their maximum parallel degree before queuing kicks in.  PARALLEL_SERVER_TARGET is set per instance (so needs to be set to the same value on all 8 nodes in a full rack Database Machine). Just as a side note, this parameter is set in processes, not in DOP, which equates to 4* Default DOP (2 processes for a DOP, default value is 2 * Default DOP, hence a default of 4 * Default DOP). Let’s say we have PARALLEL_SERVER_TARGET set to 128. With our limit set to 32 (the default) we are able to run 4 statements concurrently at the highest DOP possible on this system before we start queuing. If these 4 statements are running, any next statement will be queued. To run a system at high concurrency the PARALLEL_SERVER_TARGET should be raised from its default to be much closer (start with 60% or so) to PARALLEL_MAX_SERVERS. By using both PARALLEL_SERVER_TARGET and PARALLEL_DEGREE_LIMIT you can control easily how many statements run concurrently at good DOPs without excessive queuing. Because each workload is a little different, it makes sense to plan ahead and look at these parameters and set these based on your requirements.

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• Expected sprint completion rate and load in scrum?

  - by bjarkef

  Recently at work there have been increased focus on completion rate and load on the developers in our sprints. With completion rate I mean, if we plan 20 user stories for a sprint, what percentage of these user stories are closed at the end of the sprint. And with load I mean, if we have a sprint with 3 developers of 60 hours each, i.e. 180 hours for the sprint, how many hours worth of user stories do we schedule for the sprint. So I am really interested in others experience with this, I guess this is something everybody working with scrum deals with. My question is, what completion rate and load are expected/usual, and how are your team doing with respect to these parameters?

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• FBX 3ds max export, bad vertices

  - by instancedName

  I need to import model in OpenGL via Fbx SdK, and for testing purposes I created a simple box centered in the (0, 0, 0), length 3, in 3ds max. Here's the image: But when i exported it, and imported in the OpenGL it wasn't in the center. Then I exported it in ASCII format, and opened the file in Notepad, and really Z coordinates were 0, and 3. When I converted model to editable mesh and checked every vertex in 3ds max it had expected (+-1.5, +-1.5, +-1.5) coordinates. Can anyone help me with this one? I'm really stuck. I tried to change whole bunch of parameters in 3ds max export, but every time it changes Z koordinate.

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• Nginx + PHP-FPM executes script, but returns 404

  - by MorfiusX

  I am using Nginx + PHP-FPM to run a Wordpress based site. I have a URL that should return dynamically generated JSON data for use with the DataTables jQuery plugin. The data is returned properly, but with a return code of 404. I think this is a Nginx config issue, but I haven't been able to figure out why. The script 'getTable.php' works properly on the production version of the site which is currently using Apache. Anyone know how I can get this to work on Nginx? URL: http://dev.iloveskydiving.org/wp-content/plugins/ils-workflow/lib/getTable.php SERVER: CentOS 6 + Varnish (caching disabled for development) + Nginx + PHP-FPM + Wordpress + W3 Total Cache Nginx Config: server { # Server Parameters listen 127.0.0.1:8082; server_name dev.iloveskydiving.org; root /var/www/dev.iloveskydiving.org/html; access_log /var/www/dev.iloveskydiving.org/logs/access.log main; error_log /var/www/dev.iloveskydiving.org/logs/error.log error; index index.php; # Rewrite minified CSS and JS files location ~* \.(css|js) { if (!-f $request_filename) { rewrite ^/wp-content/w3tc/min/(.+\.(css|js))$ /wp-content/w3tc/min/index.php?file=$1 last; expires max; } } # Set a variable to work around the lack of nested conditionals set $cache_uri $request_uri; # Don't cache uris containing the following segments if ($request_uri ~* "(\/wp-admin\/|\/xmlrpc.php|\/wp-(app|cron|login|register|mail)\.php|wp-.*\.php|index\.php|wp\-comments\-popup\.php|wp\-links\-opml\.php|wp\-locations\.php)") { set $cache_uri "no cache"; } # Don't use the cache for logged in users or recent commenters if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+|wp\-postpass|wordpress_logged_in") { set $cache_uri 'no cache'; } # Use cached or actual file if they exists, otherwise pass request to WordPress location / { try_files /wp-content/w3tc/pgcache/$cache_uri/_index.html $uri $uri/ /index.php?q=$uri&$args; } # Cache static files for as long as possible location ~* \.(xml|ogg|ogv|svg|svgz|eot|otf|woff|mp4|ttf|css|rss|atom|js|jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|ppt|tar|mid|midi|wav|bmp|rtf)$ { try_files $uri =404; expires max; access_log off; } # Deny access to hidden files location ~* /\.ht { deny all; access_log off; log_not_found off; } location ~ \.php$ { try_files $uri =404; fastcgi_split_path_info ^(.+\.php)(/.+)$; include /etc/nginx/fastcgi_params; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; fastcgi_param PATH_INFO $fastcgi_script_name; fastcgi_intercept_errors on; fastcgi_pass unix:/var/lib/php-fpm/php-fpm.sock; # port where FastCGI processes were spawned } } Fast CGI Params: fastcgi_param QUERY_STRING $query_string; fastcgi_param REQUEST_METHOD $request_method; fastcgi_param CONTENT_TYPE $content_type; fastcgi_param CONTENT_LENGTH $content_length; fastcgi_param SCRIPT_NAME $fastcgi_script_name; fastcgi_param REQUEST_URI $request_uri; fastcgi_param DOCUMENT_URI $document_uri; fastcgi_param DOCUMENT_ROOT $document_root; fastcgi_param SERVER_PROTOCOL $server_protocol; fastcgi_param HTTPS $https if_not_empty; fastcgi_param GATEWAY_INTERFACE CGI/1.1; fastcgi_param SERVER_SOFTWARE nginx/$nginx_version; fastcgi_param REMOTE_ADDR $remote_addr; fastcgi_param REMOTE_PORT $remote_port; fastcgi_param SERVER_ADDR $server_addr; fastcgi_param SERVER_PORT $server_port; fastcgi_param SERVER_NAME $server_name; # PHP only, required if PHP was built with --enable-force-cgi-redirect fastcgi_param REDIRECT_STATUS 200; UPDATE: Upon further digging, it looks like Nginx is generating the 404 and PHP-FPM is executing the script properly and returning a 200. UPDATE: Here are the contents of the script: <?php /** * Connect to Wordpres */ require(dirname(__FILE__) . '/../../../../wp-blog-header.php'); /** * Define temporary array */ $aaData = array(); $aaData['aaData'] = array(); /** * Execute Query */ $query = new WP_Query( array( 'post_type' => 'post', 'posts_per_page' => '-1' ) ); foreach ($query->posts as $post) { array_push( $aaData['aaData'], array( $post->post_title ) ); } /** * Echo JSON encoded array */ echo json_encode($aaData);

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• Python 3.4 adds re.fullmatch()

  - by Jan Goyvaerts

  Python 3.4 does not bring any changes to its regular expression syntax compared to previous 3.x releases. It does add one new function to the re module called fullmatch(). This function takes a regular expression and a subject string as its parameters. It returns True if the regular expression can match the string entirely. It returns False if the string cannot be matched or if it can only be matched partially. This is useful when using a regular expression to validate user input. Do note that fullmatch() will return True if the subject string is the empty string and the regular expression can find zero-length matches. A zero-length match of a zero-length string is a complete match. So if you want to check whether the user entered a sequence of digits, use \d+ rather than \d* as the regex.

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• C#: Why Decorate When You Can Intercept

  - by James Michael Hare

  We've all heard of the old Decorator Design Pattern (here) or used it at one time or another either directly or indirectly.  A decorator is a class that wraps a given abstract class or interface and presents the same (or a superset) public interface but "decorated" with additional functionality.   As a really simplistic example, consider the System.IO.BufferedStream, it itself is a descendent of System.IO.Stream and wraps the given stream with buffering logic while still presenting System.IO.Stream's public interface:   1: Stream buffStream = new BufferedStream(rawStream); Now, let's take a look at a custom-code example.  Let's say that we have a class in our data access layer that retrieves a list of products from a database:  1: // a class that handles our CRUD operations for products 2: public class ProductDao 3: { 4: ... 5:  6: // a method that would retrieve all available products 7: public IEnumerable<Product> GetAvailableProducts() 8: { 9: var results = new List<Product>(); 10:  11: // must create the connection 12: using (var con = _factory.CreateConnection()) 13: { 14: con.ConnectionString = _productsConnectionString; 15: con.Open(); 16:  17: // create the command 18: using (var cmd = _factory.CreateCommand()) 19: { 20: cmd.Connection = con; 21: cmd.CommandText = _getAllProductsStoredProc; 22: cmd.CommandType = CommandType.StoredProcedure; 23:  24: // get a reader and pass back all results 25: using (var reader = cmd.ExecuteReader()) 26: { 27: while(reader.Read()) 28: { 29: results.Add(new Product 30: { 31: Name = reader["product_name"].ToString(), 32: ... 33: }); 34: } 35: } 36: } 37: }            38:  39: return results; 40: } 41: } Yes, you could use EF or any myriad other choices for this sort of thing, but the germaine point is that you have some operation that takes a non-trivial amount of time.  What if, during the production day I notice that my application is performing slowly and I want to see how much of that slowness is in the query versus my code.  Well, I could easily wrap the logic block in a System.Diagnostics.Stopwatch and log the results to log4net or other logging flavor of choice: 1:     // a class that handles our CRUD operations for products 2:     public class ProductDao 3:     { 4:         private static readonly ILog _log = LogManager.GetLogger(typeof(ProductDao)); 5:         ... 6:         7:         // a method that would retrieve all available products 8:         public IEnumerable<Product> GetAvailableProducts() 9:         { 10:             var results = new List<Product>(); 11:             var timer = Stopwatch.StartNew(); 12:             13:             // must create the connection 14:             using (var con = _factory.CreateConnection()) 15:             { 16:                 con.ConnectionString = _productsConnectionString; 17:                 18:                 // and all that other DB code... 19:                 ... 20:             } 21:             22:             timer.Stop(); 23:             24:             if (timer.ElapsedMilliseconds > 5000) 25:             { 26:                 _log.WarnFormat("Long query in GetAvailableProducts() took {0} ms", 27:                     timer.ElapsedMillseconds); 28:             } 29:             30:             return results; 31:         } 32:     } In my eye, this is very ugly.  It violates Single Responsibility Principle (SRP), which says that a class should only ever have one responsibility, where responsibility is often defined as a reason to change.  This class (and in particular this method) has two reasons to change: If the method of retrieving products changes. If the method of logging changes. Well, we could “simplify” this using the Decorator Design Pattern (here).  If we followed the pattern to the letter, we'd need to create a base decorator that implements the DAOs public interface and forwards to the wrapped instance.  So let's assume we break out the ProductDAO interface into IProductDAO using your refactoring tool of choice (Resharper is great for this). Now, ProductDao will implement IProductDao and get rid of all logging logic: 1:     public class ProductDao : IProductDao 2:     { 3:         // this reverts back to original version except for the interface added 4:     } 5:  And we create the base Decorator that also implements the interface and forwards all calls: 1:     public class ProductDaoDecorator : IProductDao 2:     { 3:         private readonly IProductDao _wrappedDao; 4:         5:         // constructor takes the dao to wrap 6:         public ProductDaoDecorator(IProductDao wrappedDao) 7:         { 8:             _wrappedDao = wrappedDao; 9:         } 10:         11:         ... 12:         13:         // and then all methods just forward their calls 14:         public IEnumerable<Product> GetAvailableProducts() 15:         { 16:             return _wrappedDao.GetAvailableProducts(); 17:         } 18:     } This defines our base decorator, then we can create decorators that add items of interest, and for any methods we don't decorate, we'll get the default behavior which just forwards the call to the wrapper in the base decorator: 1:     public class TimedThresholdProductDaoDecorator : ProductDaoDecorator 2:     { 3:         private static readonly ILog _log = LogManager.GetLogger(typeof(TimedThresholdProductDaoDecorator)); 4:         5:         public TimedThresholdProductDaoDecorator(IProductDao wrappedDao) : 6:             base(wrappedDao) 7:         { 8:         } 9:         10:         ... 11:         12:         public IEnumerable<Product> GetAvailableProducts() 13:         { 14:             var timer = Stopwatch.StartNew(); 15:             16:             var results = _wrapped.GetAvailableProducts(); 17:             18:             timer.Stop(); 19:             20:             if (timer.ElapsedMilliseconds > 5000) 21:             { 22:                 _log.WarnFormat("Long query in GetAvailableProducts() took {0} ms", 23:                     timer.ElapsedMillseconds); 24:             } 25:             26:             return results; 27:         } 28:     } Well, it's a bit better.  Now the logging is in its own class, and the database logic is in its own class.  But we've essentially multiplied the number of classes.  We now have 3 classes and one interface!  Now if you want to do that same logging decorating on all your DAOs, imagine the code bloat!  Sure, you can simplify and avoid creating the base decorator, or chuck it all and just inherit directly.  But regardless all of these have the problem of tying the logging logic into the code itself. Enter the Interceptors.  Things like this to me are a perfect example of when it's good to write an Interceptor using your class library of choice.  Sure, you could design your own perfectly generic decorator with delegates and all that, but personally I'm a big fan of Castle's Dynamic Proxy (here) which is actually used by many projects including Moq. What DynamicProxy allows you to do is intercept calls into any object by wrapping it with a proxy on the fly that intercepts the method and allows you to add functionality.  Essentially, the code would now look like this using DynamicProxy: 1: // Note: I like hiding DynamicProxy behind the scenes so users 2: // don't have to explicitly add reference to Castle's libraries. 3: public static class TimeThresholdInterceptor 4: { 5: // Our logging handle 6: private static readonly ILog _log = LogManager.GetLogger(typeof(TimeThresholdInterceptor)); 7:  8: // Handle to Castle's proxy generator 9: private static readonly ProxyGenerator _generator = new ProxyGenerator(); 10:  11: // generic form for those who prefer it 12: public static object Create<TInterface>(object target, TimeSpan threshold) 13: { 14: return Create(typeof(TInterface), target, threshold); 15: } 16:  17: // Form that uses type instead 18: public static object Create(Type interfaceType, object target, TimeSpan threshold) 19: { 20: return _generator.CreateInterfaceProxyWithTarget(interfaceType, target, 21: new TimedThreshold(threshold, level)); 22: } 23:  24: // The interceptor that is created to intercept the interface calls. 25: // Hidden as a private inner class so not exposing Castle libraries. 26: private class TimedThreshold : IInterceptor 27: { 28: // The threshold as a positive timespan that triggers a log message. 29: private readonly TimeSpan _threshold; 30:  31: // interceptor constructor 32: public TimedThreshold(TimeSpan threshold) 33: { 34: _threshold = threshold; 35: } 36:  37: // Intercept functor for each method invokation 38: public void Intercept(IInvocation invocation) 39: { 40: // time the method invocation 41: var timer = Stopwatch.StartNew(); 42:  43: // the Castle magic that tells the method to go ahead 44: invocation.Proceed(); 45:  46: timer.Stop(); 47:  48: // check if threshold is exceeded 49: if (timer.Elapsed > _threshold) 50: { 51: _log.WarnFormat("Long execution in {0} took {1} ms", 52: invocation.Method.Name, 53: timer.ElapsedMillseconds); 54: } 55: } 56: } 57: } Yes, it's a bit longer, but notice that: This class ONLY deals with logging long method calls, no DAO interface leftovers. This class can be used to time ANY class that has an interface or virtual methods. Personally, I like to wrap and hide the usage of DynamicProxy and IInterceptor so that anyone who uses this class doesn't need to know to add a Castle library reference.  As far as they are concerned, they're using my interceptor.  If I change to a new library if a better one comes along, they're insulated. Now, all we have to do to use this is to tell it to wrap our ProductDao and it does the rest: 1: // wraps a new ProductDao with a timing interceptor with a threshold of 5 seconds 2: IProductDao dao = TimeThresholdInterceptor.Create<IProductDao>(new ProductDao(), 5000); Automatic decoration of all methods!  You can even refine the proxy so that it only intercepts certain methods. This is ideal for so many things.  These are just some of the interceptors we've dreamed up and use: Log parameters and returns of methods to XML for auditing. Block invocations to methods and return default value (stubbing). Throw exception if certain methods are called (good for blocking access to deprecated methods). Log entrance and exit of a method and the duration. Log a message if a method takes more than a given time threshold to execute. Whether you use DynamicProxy or some other technology, I hope you see the benefits this adds.  Does it completely eliminate all need for the Decorator pattern?  No, there may still be cases where you want to decorate a particular class with functionality that doesn't apply to the world at large. But for all those cases where you are using Decorator to add functionality that's truly generic.  I strongly suggest you give this a try!

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• Box2D Static-Dynamic body joint eliminates collisions

  - by andrewz

  I have a static body A, and a dynamic body B, and a dynamic body C. A is filtered to not collide with anything, B and C collide with each other. I wish to create a joint between B and A. When I create a joint (ex. revolute), B no longer collides with C - C passes through it as if it does not exist. What am I doing wrong? How can adding a joint prevent a body from colliding with another body it used to? EDIT: I want to join B with A, and have B collide with C, but not A collide with C. In realistic terms, I'm trying to create a revolute joint between a wheel (B) and a wall (A), and have a box (C) hit the wheel and the wheel would then rotate. EDIT: I create a the simplest revolute joint I can with these parameters (C++): b2RevoluteJointDef def; def.Initialize(A, B, B -> GetWorldCenter()); world -> CreateJoint(&def);

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• Best way to throw exception and avoid code duplication

  - by JF Dion

  I am currently writing code and want to make sure all the params that get passed to a function/method are valid. Since I am writing in PHP I don't have access to all the facilities of other languages like C, C++ or Java to check for parameters values and types public function inscriptionExists($sectionId, $userId) // PHP vs. public boolean inscriptionExists(int sectionId, int userId) // Java So I have to rely on exceptions if I want to make sure that my params are both integers. Since I have a lot of places where I need to check for param validity, what would be the best way to create a validation/exception machine and avoid code duplication? I was thinking on a static factory (since I don't want to pass it to all of my classes) with a signature like: public static function factory ($value, $valueType, $exceptionType = 'InvalidArgumentException'); Which would then call the right sub process to validate based on the type. Am I on the right way, or am I going completely off the road and overthinking my problem?

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• Shadow-mapping xna

  - by Kurt Ricci

  I've been trying to implement shadows in my game and I've been following quite a few tutorials online, mainly Riemers, but I'm always getting the same 2 errors when I'm drawing my models and setting the parameters from the effect file. The errors are: This method does not accept null for this parameter. Parameter name: value and Object reference not set to an instance of an object. So I've then downloaded a sample and just replaced my model with the one found in the sample and the same errors occur. I this find very strange as it works with his model. I'm wondering if the problem is with my models (I made them myself). Here's the code where the errors occur (they start to occur after the second foreach loop). Any help would be greatly appreciated, thanks.

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• Installing Ubuntu 14.04 on macbook pro EFI

  - by user279771

  Macbook pro: mavericks, 5.2, graphics: nvidia geforce 9600M I followed the guides from here: https://help.ubuntu.com/community/UEFIBooting#Detect_.28U.29EFI_firmware_processor_architecture and http://www.rodsbooks.com/ubuntu-efi/. What I have is the following: /dev/sda apple partitions /boot / (root) swap When installing ubuntu, I did not install the boot loader during installation but did so in a chroot environment after installing grub-efi. I installed grub to /dev/sda1 (efi) which created the grub64.efi file in efi/ubuntu. This allows the refined boot manager to bring up grub and select ubuntu however, the graphics does not work. Even after adding nomodeset and removing quiet/splash from the kernel parameters. Any ideas on what could be wrong? To be clear, if I remove quiet/splash, I can see all the text startup messages being printed out however, the display manager doesn't appear to start (the screen stays black). Oddly enough though, the ubuntu startup sound can be heard.

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• Trace flags - TF 1117

  - by Damian

  I had a session about trace flags this year on the SQL Day 2014 conference that was held in Wroclaw at the end of April. The session topic is important to most of DBA's and the reason I did it was that I sometimes forget about various trace flags :). So I decided to prepare a presentation but I think it is a good idea to write posts about trace flags, too. Let's start then - today I will describe the TF 1117. I assume that we all know how to setup a TF using starting parameters or registry or in the session or on the query level. I will always write if a trace flag is local or global to make sure we know how to use it. Why do we need this trace flag? Let’s create a test database first. This is quite ordinary database as it has two data files (4 MB each) and a log file that has 1MB. The data files are able to expand by 1 MB and the log file grows by 10%: USE [master] GO CREATE DATABASE [TF1117]  ON  PRIMARY ( NAME = N'TF1117',      FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\TF1117.mdf' ,      SIZE = 4096KB ,      MAXSIZE = UNLIMITED,      FILEGROWTH = 1024KB ), ( NAME = N'TF1117_1',      FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\TF1117_1.ndf' ,      SIZE = 4096KB ,      MAXSIZE = UNLIMITED,      FILEGROWTH = 1024KB )  LOG ON ( NAME = N'TF1117_log',      FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\TF1117_log.ldf' ,      SIZE = 1024KB ,      MAXSIZE = 2048GB ,      FILEGROWTH = 10% ) GO Without the TF 1117 turned on the data files don’t grow all up at once. When a first file is full the SQL Server expands it but the other file is not expanded until is full. Why is that so important? The SQL Server proportional fill algorithm will direct new extent allocations to the file with the most available space so new extents will be written to the file that was just expanded. When the TF 1117 is enabled it will cause all files to auto grow by their specified increment. That means all files will have the same percent of free space so we still have the benefit of evenly distributed IO. The TF 1117 is global flag so it affects all databases on the instance. Of course if a filegroup contains only one file the TF does not have any effect on it. Now let’s do a simple test. First let’s create a table in which every row will fit to a single page: The table definition is pretty simple as it has two integer columns and one character column of fixed size 8000 bytes: create table TF1117Tab (      col1 int,      col2 int,      col3 char (8000) ) go Now I load some data to the table to make sure that one of the data file must grow: declare @i int select @i = 1 while (@i < 800) begin       insert into TF1117Tab  values (@i, @i+1000, 'hello')        select @i= @i + 1 end I can check the actual file size in the sys.database_files DMV: SELECT name, (size*8)/1024 'Size in MB' FROM sys.database_files  GO   As you can see only the first data file was  expanded and the other has still the initial size:   name                  Size in MB --------------------- ----------- TF1117                5 TF1117_log            1 TF1117_1              4 There is also other methods of looking at the events of file autogrows. One possibility is to create an Extended Events session and the other is to look into the default trace file:     DECLARE @path NVARCHAR(260); SELECT    @path = REVERSE(SUBSTRING(REVERSE([path]),          CHARINDEX('\', REVERSE([path])), 260)) + N'log.trc' FROM    sys.traces WHERE   is_default = 1; SELECT    DatabaseName,                 [FileName],                 SPID,                 Duration,                 StartTime,                 EndTime,                 FileType =                         CASE EventClass                                     WHEN 92 THEN 'Data'                                    WHEN 93 THEN 'Log'             END FROM sys.fn_trace_gettable(@path, DEFAULT) WHERE   EventClass IN (92,93) AND StartTime >'2014-07-12' AND DatabaseName = N'TF1117' ORDER BY   StartTime DESC;   After running the query I can see the file was expanded and how long did the process take which might be useful from the performance perspective.    Now it’s time to turn on the flag 1117. DBCC TRACEON(1117)   I dropped the database and recreated it once again. Then I ran the queries and observed the results. After loading the records I see that both files were evenly expanded: name                  Size in MB --------------------- ----------- TF1117                5 TF1117_log            1 TF1117_1              5 I found also information in the default trace. The query returned three rows. The last one is connected to my first experiment when the TF was turned off.  The two rows shows that first file was expanded by 1MB and right after that operation the second file was expanded, too. This is what is this TF all about J  

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• Allowing Access to HttpContext in WCF REST Services

  - by Rick Strahl

  If you’re building WCF REST Services you may find that WCF’s OperationContext, which provides some amount of access to Http headers on inbound and outbound messages, is pretty limited in that it doesn’t provide access to everything and sometimes in a not so convenient manner. For example accessing query string parameters explicitly is pretty painful: [OperationContract] [WebGet] public string HelloWorld() { var properties = OperationContext.Current.IncomingMessageProperties; var property = properties[HttpRequestMessageProperty.Name] as HttpRequestMessageProperty; string queryString = property.QueryString; var name = StringUtils.GetUrlEncodedKey(queryString,"Name"); return "Hello World " + name; } And that doesn’t account for the logic in GetUrlEncodedKey to retrieve the querystring value. It’s a heck of a lot easier to just do this: [OperationContract] [WebGet] public string HelloWorld() { var name = HttpContext.Current.Request.QueryString["Name"] ?? string.Empty; return "Hello World " + name; } Ok, so if you follow the REST guidelines for WCF REST you shouldn’t have to rely on reading query string parameters manually but instead rely on routing logic, but you know what: WCF REST is a PITA anyway and anything to make things a little easier is welcome. To enable the second scenario there are a couple of steps that you have to take on your service implementation and the configuration file. Add aspNetCompatibiltyEnabled in web.config Fist you need to configure the hosting environment to support ASP.NET when running WCF Service requests. This ensures that the ASP.NET pipeline is fired up and configured for every incoming request. <system.serviceModel>     <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" /> </system.serviceModel> Markup your Service Implementation with AspNetCompatibilityRequirements Attribute Next you have to mark up the Service Implementation – not the contract if you’re using a separate interface!!! – with the AspNetCompatibilityRequirements attribute: [ServiceContract(Namespace = "RateTestService")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class RestRateTestProxyService Typically you’ll want to use Allowed as the preferred option. The other options are NotAllowed and Required. Allowed will let the service run if the web.config attribute is not set. Required has to have it set. All these settings determine whether an ASP.NET host AppDomain is used for requests. Once Allowed or Required has been set on the implemented class you can make use of the ASP.NET HttpContext object. When I allow for ASP.NET compatibility in my WCF services I typically add a property that exposes the Context and Request objects a little more conveniently: public HttpContext Context { get { return HttpContext.Current; } } public HttpRequest Request { get { return HttpContext.Current.Request; } } While you can also access the Response object and write raw data to it and manipulate headers THAT is probably not such a good idea as both your code and WCF will end up writing into the output stream. However it might be useful in some situations where you need to take over output generation completely and return something completely custom. Remember though that WCF REST DOES actually support that as well with Stream responses that essentially allow you to return any kind of data to the client so using Response should really never be necessary. Should you or shouldn’t you? WCF purists will tell you never to muck with the platform specific features or the underlying protocol, and if you can avoid it you definitely should avoid it. Querystring management in particular can be handled largely with Url Routing, but there are exceptions of course. Try to use what WCF natively provides – if possible as it makes the code more portable. For example, if you do enable ASP.NET Compatibility you won’t be able to self host a WCF REST service. At the same time realize that especially in WCF REST there are number of big holes or access to some features are a royal pain and so it’s not unreasonable to access the HttpContext directly especially if it’s only for read-only access. Since everything in REST works of URLS and the HTTP protocol more control and easier access to HTTP features is a key requirement to building flexible services. It looks like vNext of the WCF REST stuff will feature many improvements along these lines with much deeper native HTTP support that is often so useful in REST applications along with much more extensibility that allows for customization of the inputs and outputs as data goes through the request pipeline. I’m looking forward to this stuff as WCF REST as it exists today still is a royal pain (in fact I’m struggling with a mysterious version conflict/crashing error on my machine that I have not been able to resolve – grrrr…).© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  WCF  

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• How properly perform passing operation result to View

  - by atomAltera

  I'm developing web site on self made MVC engine. I have actionController that handles operations like register, login, post submit and etc. actionController receives operation name and parameters. Of course it mast handle errors such user with same nick already exists or password is to short about which action handler have to notify user. The question is which is the best way to organize errors, such that View could easily get localized user notification message. I see two ways First one: define error constants like ERR_NICK_BUSY = '1' ERR_NICK_INVALID = '2' ... and localization map local[ERR_NICK_BUSY] = 'User with the same nick already registered' local[ERR_NICK_INVALID ] = 'Nick, you entered is invalid' ... And second one: define abstract constants like ERR_FIELD_BUSY = '1' ERR_FIELD_INVALID = '2' ... and pass them with field name. In this case localization looks like local['nick_'+ERR_FIELD_BUSY] = 'User with the same nick already registered' ... I don't like both this methods. Can you advise something else?

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• Java code generation from class diagram

  - by Sanjay

  I'm on the way developing a Java application where user can provide a class diagram and get the corresponding Java code. I don't know how can I let the user interactively draw a class diagram in Java. I am currently getting the required parameters like attributes, functions directly from the user, and then I render a class diagram for him. I show the class diagram on a jdialog. Is there a better way to do this? This is an example of a class diagram, I need to generate this from a Java program, given the values and relationship.

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• Tutorial: Getting Started with the NoSQL JavaScript / Node.js API for MySQL Cluster

  - by Mat Keep

  Tutorial authored by Craig Russell and JD Duncan  The MySQL Cluster team are working on a new NoSQL JavaScript connector for MySQL. The objectives are simplicity and high performance for JavaScript users: - allows end-to-end JavaScript development, from the browser to the server and now to the world's most popular open source database - native "NoSQL" access to the storage layer without going first through SQL transformations and parsing. Node.js is a complete web platform built around JavaScript designed to deliver millions of client connections on commodity hardware. With the MySQL NoSQL Connector for JavaScript, Node.js users can easily add data access and persistence to their web, cloud, social and mobile applications. While the initial implementation is designed to plug and play with Node.js, the actual implementation doesn't depend heavily on Node, potentially enabling wider platform support in the future. Implementation The architecture and user interface of this connector are very different from other MySQL connectors in a major way: it is an asynchronous interface that follows the event model built into Node.js. To make it as easy as possible, we decided to use a domain object model to store the data. This allows for users to query data from the database and have a fully-instantiated object to work with, instead of having to deal with rows and columns of the database. The domain object model can have any user behavior that is desired, with the NoSQL connector providing the data from the database. To make it as fast as possible, we use a direct connection from the user's address space to the database. This approach means that no SQL (pun intended) is needed to get to the data, and no SQL server is between the user and the data. The connector is being developed to be extensible to multiple underlying database technologies, including direct, native access to both the MySQL Cluster "ndb" and InnoDB storage engines. The connector integrates the MySQL Cluster native API library directly within the Node.js platform itself, enabling developers to seamlessly couple their high performance, distributed applications with a high performance, distributed, persistence layer delivering 99.999% availability. The following sections take you through how to connect to MySQL, query the data and how to get started. Connecting to the database A Session is the main user access path to the database. You can get a Session object directly from the connector using the openSession function: var nosql = require("mysql-js"); var dbProperties = {     "implementation" : "ndb",     "database" : "test" }; nosql.openSession(dbProperties, null, onSession); The openSession function calls back into the application upon creating a Session. The Session is then used to create, delete, update, and read objects. Reading data The Session can read data from the database in a number of ways. If you simply want the data from the database, you provide a table name and the key of the row that you want. For example, consider this schema: create table employee (   id int not null primary key,   name varchar(32),   salary float ) ENGINE=ndbcluster; Since the primary key is a number, you can provide the key as a number to the find function. function onSession = function(err, session) {   if (err) {     console.log(err);     ... error handling   }   session.find('employee', 0, onData); }; function onData = function(err, data) {   if (err) {     console.log(err);     ... error handling   }   console.log('Found: ', JSON.stringify(data));   ... use data in application }; If you want to have the data stored in your own domain model, you tell the connector which table your domain model uses, by specifying an annotation, and pass your domain model to the find function. var annotations = new nosql.Annotations(); function Employee = function(id, name, salary) {   this.id = id;   this.name = name;   this.salary = salary;   this.giveRaise = function(percent) {     this.salary *= percent;   } }; annotations.mapClass(Employee, {'table' : 'employee'}); function onSession = function(err, session) {   if (err) {     console.log(err);     ... error handling   }   session.find(Employee, 0, onData); }; Updating data You can update the emp instance in memory, but to make the raise persistent, you need to write it back to the database, using the update function. function onData = function(err, emp) {   if (err) {     console.log(err);     ... error handling   }   console.log('Found: ', JSON.stringify(emp));   emp.giveRaise(0.12); // gee, thanks!   session.update(emp); // oops, session is out of scope here }; Using JavaScript can be tricky because it does not have the concept of block scope for variables. You can create a closure to handle these variables, or use a feature of the connector to remember your variables. The connector api takes a fixed number of parameters and returns a fixed number of result parameters to the callback function. But the connector will keep track of variables for you and return them to the callback. So in the above example, change the onSession function to remember the session variable, and you can refer to it in the onData function: function onSession = function(err, session) {   if (err) {     console.log(err);     ... error handling   }   session.find(Employee, 0, onData, session); }; function onData = function(err, emp, session) {   if (err) {     console.log(err);     ... error handling   }   console.log('Found: ', JSON.stringify(emp));   emp.giveRaise(0.12); // gee, thanks!   session.update(emp, onUpdate); // session is now in scope }; function onUpdate = function(err, emp) {   if (err) {     console.log(err);     ... error handling   } Inserting data Inserting data requires a mapped JavaScript user function (constructor) and a session. Create a variable and persist it: function onSession = function(err, session) {   var data = new Employee(999, 'Mat Keep', 20000000);   session.persist(data, onInsert);   } }; Deleting data To remove data from the database, use the session remove function. You use an instance of the domain object to identify the row you want to remove. Only the key field is relevant. function onSession = function(err, session) {   var key = new Employee(999);   session.remove(Employee, onDelete);   } }; More extensive queries We are working on the implementation of more extensive queries along the lines of the criteria query api. Stay tuned. How to evaluate The MySQL Connector for JavaScript is available for download from labs.mysql.com. Select the build: MySQL-Cluster-NoSQL-Connector-for-Node-js You can also clone the project on GitHub Since it is still early in development, feedback is especially valuable (so don't hesitate to leave comments on this blog, or head to the MySQL Cluster forum). Try it out and see how easy (and fast) it is to integrate MySQL Cluster into your Node.js platforms. You can learn more about other previewed functionality of MySQL Cluster 7.3 here

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• Advanced Search Stored procedure

  - by Ray Eatmon

  So I am working on an MVC ASP.NET web application which centers around lots of data and data manipulation. PROBLEM OVERVIEW: We have an advanced search with 25 different filter criteria. I am using a stored procedure for this search. The stored procedure takes in parameters, filter for specific objects, and calculates return data from those objects. It queries large tables 14 millions records on some table, filtering and temp tables helped alleviate some of the bottle necks for those queries. ISSUE: The stored procedure used to take 1 min to run, which creates a timeout returning 0 results to the browser. I rewrote the procedure and got it down to 21 secs so the timeout does not occur. This ONLY occurs this slow the FIRST time the search is run, after that it takes like 5 secs. I am wondering should I take a different approach to this problem, should I worry about this type of performance issue if it does not timeout?

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• Ask the Readers: Favorite Deal App?

  - by Jason Fitzpatrick

  Black Friday is mere days away and the holiday shopping season is upon us. This week we want to hear about your favorite deals apps—how do you find the best deals on the go? The parameters for this week’s Ask the Readers question are pretty straight forward: we want to hear about your favorite deal finding/deal comparison smart phone app. Whether it’s for Android, iOS, or a web site with a very cleanly formatted mobile interface, we want to hear about how you score serious deals out in the field. How do you know if the deal you see in the store is the best deal? Sound off in the comments with your favorite deal app and then check in on Friday for the What You Said roundup. How to See What Web Sites Your Computer is Secretly Connecting To HTG Explains: When Do You Need to Update Your Drivers? How to Make the Kindle Fire Silk Browser *Actually* Fast!

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• Complexity of a web application

  - by Dominik G

  I am currently writing my Master's Thesis on maintainability of a web application. I found some methods like the "Maintainability Index" by Coleman et.al. or the "Software Maintainability Index" by Muthanna et.al. For both of them one needs to calculate the cyclomatic complexity. So my question is: Is it possible to measure the cyclomatic complexity of a web application? In my opinion there are three parts to a web application: Server code (PHP, C#, Python, Perl, etc.) Client code (JavaScript) HTML (links and forms as operators, GET-parameters and form fields as operands!?) What do you think? Is there another point of view on the complexity of web application? Did I miss something?

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• Server Memory with Magento

  - by Mohamed Elgharabawy

  I have a cloud server with the following specifications: 2vCPUs 4G RAM 160GB Disk Space Network 400Mb/s System Image: Ubuntu 12.04 LTS I am only running Magento CE 1.7.0.2 on this server. Nothing else. Usually, the server has a loading time of 4-5 seconds. Recently, this has dropped to over 30 seconds and sometimes the server just goes away and I get HTTP error reports to my email stating that HTTP requests took more than 20000ms. Running top command and sorting them returns the following: top - 15:29:07 up 3:40, 1 user, load average: 28.59, 25.95, 22.91 Tasks: 112 total, 30 running, 82 sleeping, 0 stopped, 0 zombie Cpu(s): 90.2%us, 9.3%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.3%si, 0.2%st PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 31901 www-data 20 0 360m 71m 5840 R 7 1.8 1:39.51 apache2 32084 www-data 20 0 362m 72m 5548 R 7 1.8 1:31.56 apache2 32089 www-data 20 0 348m 59m 5660 R 7 1.5 1:41.74 apache2 32295 www-data 20 0 343m 54m 5532 R 7 1.4 2:00.78 apache2 32303 www-data 20 0 354m 65m 5260 R 7 1.6 1:38.76 apache2 32304 www-data 20 0 346m 56m 5544 R 7 1.4 1:41.26 apache2 32305 www-data 20 0 348m 59m 5640 R 7 1.5 1:50.11 apache2 32291 www-data 20 0 358m 69m 5256 R 6 1.7 1:44.26 apache2 32517 www-data 20 0 345m 56m 5532 R 6 1.4 1:45.56 apache2 30473 www-data 20 0 355m 66m 5680 R 6 1.7 2:00.05 apache2 32093 www-data 20 0 352m 63m 5848 R 6 1.6 1:53.23 apache2 32302 www-data 20 0 345m 56m 5512 R 6 1.4 1:55.87 apache2 32433 www-data 20 0 346m 57m 5500 S 6 1.4 1:31.58 apache2 32638 www-data 20 0 354m 65m 5508 R 6 1.6 1:36.59 apache2 32230 www-data 20 0 347m 57m 5524 R 6 1.4 1:33.96 apache2 32231 www-data 20 0 355m 66m 5512 R 6 1.7 1:37.47 apache2 32233 www-data 20 0 354m 64m 6032 R 6 1.6 1:59.74 apache2 32300 www-data 20 0 355m 66m 5672 R 6 1.7 1:43.76 apache2 32510 www-data 20 0 347m 58m 5512 R 6 1.5 1:42.54 apache2 32521 www-data 20 0 348m 59m 5508 R 6 1.5 1:47.99 apache2 32639 www-data 20 0 344m 55m 5512 R 6 1.4 1:34.25 apache2 32083 www-data 20 0 345m 56m 5696 R 5 1.4 1:59.42 apache2 32085 www-data 20 0 347m 58m 5692 R 5 1.5 1:42.29 apache2 32293 www-data 20 0 353m 64m 5676 R 5 1.6 1:52.73 apache2 32301 www-data 20 0 348m 59m 5564 R 5 1.5 1:49.63 apache2 32528 www-data 20 0 351m 62m 5520 R 5 1.6 1:36.11 apache2 31523 mysql 20 0 3460m 576m 8288 S 5 14.4 2:06.91 mysqld 32002 www-data 20 0 345m 55m 5512 R 5 1.4 2:01.88 apache2 32080 www-data 20 0 357m 68m 5512 S 5 1.7 1:31.30 apache2 32163 www-data 20 0 347m 58m 5512 S 5 1.5 1:58.68 apache2 32509 www-data 20 0 345m 56m 5504 R 5 1.4 1:49.54 apache2 32306 www-data 20 0 358m 68m 5504 S 4 1.7 1:53.29 apache2 32165 www-data 20 0 344m 55m 5524 S 4 1.4 1:40.71 apache2 32640 www-data 20 0 345m 56m 5528 R 4 1.4 1:36.49 apache2 31888 www-data 20 0 359m 70m 5664 R 4 1.8 1:57.07 apache2 32511 www-data 20 0 357m 67m 5512 S 3 1.7 1:47.00 apache2 32054 www-data 20 0 357m 68m 5660 S 2 1.7 1:53.10 apache2 1 root 20 0 24452 2276 1232 S 0 0.1 0:01.58 init Moreover, running free -m returns the following: total used free shared buffers cached Mem: 4003 3919 83 0 118 901 -/+ buffers/cache: 2899 1103 Swap: 0 0 0 To investigate this further, I have installed apache buddy, it recommeneded that I need to reduce the maxclient connections. Which I did. I also installed MysqlTuner and it suggests that I need to set my innodb_buffer_pool_size to = 3.0G. However, I cannot do that, since the whole memory is 4G. Here is the output from apache buddy: ### GENERAL REPORT ### Settings considered for this report: Your server's physical RAM: 4003MB Apache's MaxClients directive: 40 Apache MPM Model: prefork Largest Apache process (by memory): 73.77MB [ OK ] Your MaxClients setting is within an acceptable range. Max potential memory usage: 2950.8 MB Percentage of RAM allocated to Apache 73.72 % And this is the output of MySQLTuner: -------- Performance Metrics ------------------------------------------------- [--] Up for: 47m 22s (675K q [237.552 qps], 12K conn, TX: 1B, RX: 300M) [--] Reads / Writes: 45% / 55% [--] Total buffers: 2.1G global + 2.7M per thread (151 max threads) [OK] Maximum possible memory usage: 2.5G (64% of installed RAM) [OK] Slow queries: 0% (0/675K) [OK] Highest usage of available connections: 26% (40/151) [OK] Key buffer size / total MyISAM indexes: 36.0M/18.7M [OK] Key buffer hit rate: 100.0% (245K cached / 105 reads) [OK] Query cache efficiency: 92.5% (500K cached / 541K selects) [!!] Query cache prunes per day: 302886 [OK] Sorts requiring temporary tables: 0% (1 temp sorts / 15K sorts) [!!] Joins performed without indexes: 12135 [OK] Temporary tables created on disk: 25% (8K on disk / 32K total) [OK] Thread cache hit rate: 90% (1K created / 12K connections) [!!] Table cache hit rate: 17% (400 open / 2K opened) [OK] Open file limit used: 12% (123/1K) [OK] Table locks acquired immediately: 100% (196K immediate / 196K locks) [!!] InnoDB buffer pool / data size: 2.0G/3.5G [OK] InnoDB log waits: 0 -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance MySQL started within last 24 hours - recommendations may be inaccurate Enable the slow query log to troubleshoot bad queries Adjust your join queries to always utilize indexes Increase table_cache gradually to avoid file descriptor limits Read this before increasing table_cache over 64: http://bit.ly/1mi7c4C Variables to adjust: query_cache_size ( 64M) join_buffer_size ( 128.0K, or always use indexes with joins) table_cache ( 400) innodb_buffer_pool_size (= 3G) Last but not least, the server still has more than 60% of free disk space. Now, based on the above, I have few questions: Are these numbers normal? Do they make sense? Do I need to upgrade the server? If I don't need to upgrade and my configuration is not correct, how do I optimize it?

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• Google De-Index many pages at once?

  - by Jakobud

  On one of our websites, Google has been indexing something it wasn't supposed to. We fixed the problem so it shouldn't happen anymore, but are interested in requesting that Google de-index these pages. The problem is that there are about 10,000 pages. They all look similar to this: http://www.mysite.com/file.php?o=34995 http://www.mysite.com/file.php?o=4566 http://www.mysite.com/file.php?o=223af http://www.mysite.com/file.php?o=6ga3h http://www.mysite.com/file.php?o=sfh45a etc... All the pages are file.php with get parameters like above. Is it possible to put in a de-index request like: http://www.mysite.com/file.php* so that Google removes all 10,000 pages?

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• Modified Strategy Design Pattern

  - by Samuel Walker

  I've started looking into Design Patterns recently, and one thing I'm coding would suit the Strategy pattern perfectly, except for one small difference. Essentially, some (but not all) of my algorithms, need an extra parameter or two passed to them. So I'll either need to pass them an extra parameter when I invoke their calculate method or store them as variables inside the ConcreteAlgorithm class, and be able to update them before I call the algorithm. Is there a design pattern for this need / How could I implement this while sticking to the Strategy Pattern? I've considered passing the client object to all the algorithms, and storing the variables in there, then using that only when the particular algorithm needs it. However, I think this is both unwieldy, and defeats the point of the strategy pattern. Just to be clear I'm implementing in Java, and so don't have the luxury of optional parameters (which would solve this nicely).

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• Day 4 - Game Sprites In Action

  - by dapostolov

  Yesterday I drew an image on the screen. Most exciting, but ... I spent more time blogging about it then actual coding. So this next little while I'm going to streamline my game and research and simply post key notes. Quick notes on the last session: The most important thing I wanted to point out were the following methods:           spriteBatch.Begin(SpriteBlendMode.AlphaBlend);           spriteBatch.Draw(sprite, position, Color.White);           spriteBatch.End(); The spriteBatch object is used to draw Textures and a 2D texture is called a Sprite A texture is generally an image, which is called an Asset in XNA The Draw Method in the Game1.cs is looped (until exit) and utilises the spriteBatch object to draw a Scene To begin drawing a Scene you call the Begin Method. To end a Scene you call the End Method. And to place an image on the Scene you call the Draw method. The most simple implementation of the draw method is:           spriteBatch.Draw(sprite, position, Color.White); 1) sprite - the 2D texture you loaded to draw 2) position - the 2d vector, a set of x & y coordinates 3) Color.White - the tint to apply to the texture, in this case, white light = nothing, nada, no tint. Game Sprites In Action! Today, I played around with Draw methods to get comfortable with their "quirks". The following is an example of the above draw method, but with more parameters available for us to use. Let's investigate!             spriteBatch.Draw(sprite, position2, null, Color.White, MathHelper.ToRadians(45.0f), new Vector2(sprite.Width / 2, sprite.Height / 2), 1.0F, SpriteEffects.None, 0.0F); The parameters (in order): 1) sprite  the texture to display 2) position2 the position on the screen / scene this can also be a rectangle 3) null the portion of the image to display within an image null = display full image this is generally used for animation strips / grids (more on this below) 4) Color.White Texture tinting White = no tint 5) MathHelper.ToRadians(45.0f) rotation of the object, in this case 45 degrees rotates from the set plotting point. 6) new Vector(0,0) the plotting point in this case the top left corner the image will rotate from the top left of the texture in the code above, the point is set to the middle of the image. 7) 1.0f Image scaling (1x) 8) SpriteEffects.None you can flip the image horizontally or vertically 9) 0.0f The z index of the image. 0 = closer, 1 behind? And playing around with different combinations I was able to come up with the following whacky display:   Checking off Yesterdays Intention List: learn game development terminology (in progress) - We learned sprite, scene, texture, and asset. how to place and position (rotate) a static image on the screen (completed) - The thing to note was, it's was in radians and I found a cool helper method to convert degrees into radians. Also, the image rotates from it's specified point. how to layer static images on the screen (completed) - I couldn't seem to get the zIndex working, but one things for sure, the order you draw the image in also determines how it is rendered on the screen. understand image scaling (in progress) - I'm not sure I have this fully covered, but for the most part plug a number in the scaling field and the image grows / shrinks accordingly. can we reuse images? (completed) - yes, I loaded one image and plotted the bugger all over the screen. understand how framerate is handled in XNA (in progress) - I hacked together some code to display the framerate each second. A framerate of 60 appears to be the standard. Interesting to note, the GameTime object does provide you with some cool timing capabilities, such as...is the game running slow? Need to investigate this down the road. how to display text , basic shapes, and colors on the screen (in progress) - i got text rendered on the screen, and i understand containing rectangles. However, I didn't display "shapes" & "colors" how to interact with an image (collision of user input?) (todo) how to animate an image and understand basic animation techniques (in progress) - I was able to create a stripe animation of numbers ranging from 1 - 4, each block was 40 x 40 pixles for a total stripe size of 160 x 40. Using the portion (source Rectangle) parameter, i limited this display to each section at varying intervals. It was interesting to note my first implementation animated at rocket speed. I then tried to create a smoother animation by limiting the redraw capacity, which seemed to work. I guess a little more research will have to be put into this for animating characters / scenes. how to detect colliding images or screen edges (todo) - but the rectangle object can detect collisions I believe. how to manipulate the image, lets say colors, stretching (in progress) - I haven't figured out how to modify a specific color to be another color, but the tinting parameter definately could be used. As for stretching, use the rectangle object as the positioning and the image will stretch to fit! how to focus on a segment of an image...like only displaying a frame on a film reel (completed) - as per basic animation techniques what's the best way to manage images (compression, storage, location, prevent artwork theft, etc.) (todo) Tomorrows Intention Tomorrow I am going to take a stab at rendering a game menu and from there I'm going to investigate how I can improve upon the code and techniques. Intention List: Render a menu, fancy or not Show the mouse cursor Hook up click event A basic animation of somesort Investigate image / menu techniques D.

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• What's the difference between Scala and Red Hat's Ceylon language?

  - by John Bryant

  Red Hat's Ceylon language has some interesting improvements over Java: The overall vision: learn from Java's mistakes, keep the good, ditch the bad The focus on readability and ease of learning/use Static Typing (find errors at compile time, not run time) No “special” types, everything is an object Named and Optional parameters (C# 4.0) Nullable types (C# 2.0) No need for explicit getter/setters until you are ready for them (C# 3.0) Type inference via the "local" keyword (C# 3.0 "var") Sequences (arrays) and their accompanying syntactic sugariness (C# 3.0) Straight-forward implementation of higher-order functions I don't know Scala but have heard it offers some similar advantages over Java. How would Scala compare to Ceylon in this respect?

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