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• Using TPL and PLINQ to raise performance of feed aggregator

  - by DigiMortal

  In this posting I will show you how to use Task Parallel Library (TPL) and PLINQ features to boost performance of simple RSS-feed aggregator. I will use here only very basic .NET classes that almost every developer starts from when learning parallel programming. Of course, we will also measure how every optimization affects performance of feed aggregator. Feed aggregator Our feed aggregator works as follows: Load list of blogs Download RSS-feed Parse feed XML Add new posts to database Our feed aggregator is run by task scheduler after every 15 minutes by example. We will start our journey with serial implementation of feed aggregator. Second step is to use task parallelism and parallelize feeds downloading and parsing. And our last step is to use data parallelism to parallelize database operations. We will use Stopwatch class to measure how much time it takes for aggregator to download and insert all posts from all registered blogs. After every run we empty posts table in database. Serial aggregation Before doing parallel stuff let’s take a look at serial implementation of feed aggregator. All tasks happen one after other. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();           for (var index = 0; index <blogs.Count; index++)         {              ImportFeed(blogs[index]);         }     }       private void ImportFeed(BlogDto blog)     {         if(blog == null)             return;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                 }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)         {             SaveRssFeedItem(item, blog.Id, blog.CreatedById);         }     }       private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } Serial implementation of feed aggregator downloads and inserts all posts with 25.46 seconds. Task parallelism Task parallelism means that separate tasks are run in parallel. You can find out more about task parallelism from MSDN page Task Parallelism (Task Parallel Library) and Wikipedia page Task parallelism. Although finding parts of code that can run safely in parallel without synchronization issues is not easy task we are lucky this time. Feeds import and parsing is perfect candidate for parallel tasks. We can safely parallelize feeds import because importing tasks doesn’t share any resources and therefore they don’t also need any synchronization. After getting the list of blogs we iterate through the collection and start new TPL task for each blog feed aggregation. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {          var uri = new Uri(blog.RssUrl);          var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)          {              SaveRssFeedItem(item, blog.Id, blog.CreatedById);          }     }     private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } You should notice first signs of the power of TPL. We made only minor changes to our code to parallelize blog feeds aggregating. On my machine this modification gives some performance boost – time is now 17.57 seconds. Data parallelism There is one more way how to parallelize activities. Previous section introduced task or operation based parallelism, this section introduces data based parallelism. By MSDN page Data Parallelism (Task Parallel Library) data parallelism refers to scenario in which the same operation is performed concurrently on elements in a source collection or array. In our code we have independent collections we can process in parallel – imported feed entries. As checking for feed entry existence and inserting it if it is missing from database doesn’t affect other entries the imported feed entries collection is ideal candidate for parallelization. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           feed.Channel.Items.AsParallel().ForAll(a =>         {             SaveRssFeedItem(a, blog.Id, blog.CreatedById);         });      }        private void ImportAtomFeed(BlogDto blog)      {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           feed.Entries.AsParallel().ForAll(a =>         {              SaveAtomFeedEntry(a, blog.Id, blog.CreatedById);         });      } } We did small change again and as the result we parallelized checking and saving of feed items. This change was data centric as we applied same operation to all elements in collection. On my machine I got better performance again. Time is now 11.22 seconds. Results Let’s visualize our measurement results (numbers are given in seconds). As we can see then with task parallelism feed aggregation takes about 25% less time than in original case. When adding data parallelism to task parallelism our aggregation takes about 2.3 times less time than in original case. More about TPL and PLINQ Adding parallelism to your application can be very challenging task. You have to carefully find out parts of your code where you can safely go to parallel processing and even then you have to measure the effects of parallel processing to find out if parallel code performs better. If you are not careful then troubles you will face later are worse than ones you have seen before (imagine error that occurs by average only once per 10000 code runs). Parallel programming is something that is hard to ignore. Effective programs are able to use multiple cores of processors. Using TPL you can also set degree of parallelism so your application doesn’t use all computing cores and leaves one or more of them free for host system and other processes. And there are many more things in TPL that make it easier for you to start and go on with parallel programming. In next major version all .NET languages will have built-in support for parallel programming. There will be also new language constructs that support parallel programming. Currently you can download Visual Studio Async to get some idea about what is coming. Conclusion Parallel programming is very challenging but good tools offered by Visual Studio and .NET Framework make it way easier for us. In this posting we started with feed aggregator that imports feed items on serial mode. With two steps we parallelized feed importing and entries inserting gaining 2.3 times raise in performance. Although this number is specific to my test environment it shows clearly that parallel programming may raise the performance of your application significantly.

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• Forcing an External Activation with Service Broker

  - by Davide Mauri

  In these last days I’ve been working quite a lot with Service Broker, a technology I’m really happy to work with, since it can give a lot of satisfaction. The scale-out solution one can easily build is simply astonishing. I’m helping a company to build a very scalable and – yet almost inexpensive – invoicing system that has to be able to scale out using commodity hardware. To offload the work from the main server to satellite “compute nodes” (yes, I’ve borrowed this term from PDW) we’re using Service Broker and the External Activator application available in the SQL Server Feature Pack. For those who are not used to work with SSB, the External Activation is a feature that allows you to intercept the arrival of a message in a queue right from your application code. http://msdn.microsoft.com/en-us/library/ms171617.aspx (Look for “Event-Based Activation”) In order to make life even more easier, Microsoft released the External Activation application that saves you even from writing even this code. http://blogs.msdn.com/b/sql_service_broker/archive/tags/external+activator/ The External Activator application can be configured to execute your own application so that each time a message – an invoice in my case – arrives in the target queue, the invoking application is executed and the invoice is calculated. The very nice feature of External Activator is that it can automatically execute as many configured application in order to process as many messages as your system can handle.  This also a lot of create a scale-out solution, leaving to the developer only a fraction of the problems that usually came with asynchronous programming. Developers are also shielded from Service Broker since everything can be encapsulated in Stored Procedures, so that – for them – developing such scale-out asynchronous solution is not much more complex than just executing a bunch of Stored Procedures. Now, if everything works correctly, you don’t have to bother of anything else. You put messages in the queue and your application, invoked by the External Activator, process them. But what happen if for some reason your application fails to process the messages. For examples, it crashes? The message is safe in the queue so you just need to process it again. But your application is invoked by the External Activator application, so now the question is, how do you wake up that app? Service Broker will engage the activation process only if certain conditions are met: http://msdn.microsoft.com/en-us/library/ms171601.aspx But how we can invoke the activation process manually, without having to wait for another message to arrive (the arrival of a new message is a condition that can fire the activation process)? The “trick” is to do manually with the activation process does: sending a system message to a queue in charge of handling External Activation messages: declare @conversationHandle uniqueidentifier; declare @n xml = N' <EVENT_INSTANCE>   <EventType>QUEUE_ACTIVATION</EventType>   <PostTime>' + CONVERT(CHAR(24),GETDATE(),126) + '</PostTime>   <SPID>' + CAST(@@SPID AS VARCHAR(9)) + '</SPID>   <ServerName>[your_server_name]</ServerName>   <LoginName>[your_login_name]</LoginName>   <UserName>[your_user_name]</UserName>   <DatabaseName>[your_database_name]</DatabaseName>   <SchemaName>[your_queue_schema_name]</SchemaName>   <ObjectName>[your_queue_name]</ObjectName>   <ObjectType>QUEUE</ObjectType> </EVENT_INSTANCE>' begin dialog conversation     @conversationHandle from service        [<your_initiator_service_name>] to service          '<your_event_notification_service>' on contract         [http://schemas.microsoft.com/SQL/Notifications/PostEventNotification] with     encryption = off,     lifetime = 6000 ; send on conversation     @conversationHandle message type     [http://schemas.microsoft.com/SQL/Notifications/EventNotification] (@n) ;     end conversation @conversationHandle; That’s it! Put the code in a Stored Procedure and you can add to your application a button that says “Force Queue Processing” (or something similar) in order to start the activation process whenever you need it (which should not occur too frequently but it may happen). PS I know that the “fire-and-forget” (ending the conversation without waiting for an answer) technique is not a best practice, but in this case I don’t see how it can hurts so I decided to stay very close to the KISS principle []

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• Using Stub Objects

  - by user9154181

  Having told the long and winding tale of where stub objects came from and how we use them to build Solaris, I'd like to focus now on the the nuts and bolts of building and using them. The following new features were added to the Solaris link-editor (ld) to support the production and use of stub objects: -z stub This new command line option informs ld that it is to build a stub object rather than a normal object. In this mode, it accepts the same command line arguments as usual, but will quietly ignore any objects and sharable object dependencies. STUB_OBJECT Mapfile Directive In order to build a stub version of an object, its mapfile must specify the STUB_OBJECT directive. When producing a non-stub object, the presence of STUB_OBJECT causes the link-editor to perform extra validation to ensure that the stub and non-stub objects will be compatible. ASSERT Mapfile Directive All data symbols exported from the object must have an ASSERT symbol directive in the mapfile that declares them as data and supplies the size, binding, bss attributes, and symbol aliasing details. When building the stub objects, the information in these ASSERT directives is used to create the data symbols. When building the real object, these ASSERT directives will ensure that the real object matches the linking interface presented by the stub. Although ASSERT was added to the link-editor in order to support stub objects, they are a general purpose feature that can be used independently of stub objects. For instance you might choose to use an ASSERT directive if you have a symbol that must have a specific address in order for the object to operate properly and you want to automatically ensure that this will always be the case. The material presented here is derived from a document I originally wrote during the development effort, which had the dual goals of providing supplemental materials for the stub object PSARC case, and as a set of edits that were eventually applied to the Oracle Solaris Linker and Libraries Manual (LLM). The Solaris 11 LLM contains this information in a more polished form. Stub Objects A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be used at runtime. However, an application can be built against a stub object, where the stub object provides the real object name to be used at runtime, and then use the real object at runtime. When building a stub object, the link-editor ignores any object or library files specified on the command line, and these files need not exist in order to build a stub. Since the compilation step can be omitted, and because the link-editor has relatively little work to do, stub objects can be built very quickly. Stub objects can be used to solve a variety of build problems: Speed Modern machines, using a version of make with the ability to parallelize operations, are capable of compiling and linking many objects simultaneously, and doing so offers significant speedups. However, it is typical that a given object will depend on other objects, and that there will be a core set of objects that nearly everything else depends on. It is necessary to impose an ordering that builds each object before any other object that requires it. This ordering creates bottlenecks that reduce the amount of parallelization that is possible and limits the overall speed at which the code can be built. Complexity/Correctness In a large body of code, there can be a large number of dependencies between the various objects. The makefiles or other build descriptions for these objects can become very complex and difficult to understand or maintain. The dependencies can change as the system evolves. This can cause a given set of makefiles to become slightly incorrect over time, leading to race conditions and mysterious rare build failures. Dependency Cycles It might be desirable to organize code as cooperating shared objects, each of which draw on the resources provided by the other. Such cycles cannot be supported in an environment where objects must be built before the objects that use them, even though the runtime linker is fully capable of loading and using such objects if they could be built. Stub shared objects offer an alternative method for building code that sidesteps the above issues. Stub objects can be quickly built for all the shared objects produced by the build. Then, all the real shared objects and executables can be built in parallel, in any order, using the stub objects to stand in for the real objects at link-time. Afterwards, the executables and real shared objects are kept, and the stub shared objects are discarded. Stub objects are built from a mapfile, which must satisfy the following requirements. The mapfile must specify the STUB_OBJECT directive. This directive informs the link-editor that the object can be built as a stub object, and as such causes the link-editor to perform validation and sanity checking intended to guarantee that an object and its stub will always provide identical linking interfaces. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data exported from the object must have an ASSERT symbol attribute in the mapfile to specify the symbol type, size, and bss attributes. In the case where there are multiple symbols that reference the same data, the ASSERT for one of these symbols must specify the TYPE and SIZE attributes, while the others must use the ALIAS attribute to reference this primary symbol. Given such a mapfile, the stub and real versions of the shared object can be built using the same command line for each, adding the '-z stub' option to the link for the stub object, and omiting the option from the link for the real object. To demonstrate these ideas, the following code implements a shared object named idx5, which exports data from a 5 element array of integers, with each element initialized to contain its zero-based array index. This data is available as a global array, via an alternative alias data symbol with weak binding, and via a functional interface. % cat idx5.c int _idx5[5] = { 0, 1, 2, 3, 4 }; #pragma weak idx5 = _idx5 int idx5_func(int index) { if ((index 4)) return (-1); return (_idx5[index]); } A mapfile is required to describe the interface provided by this shared object. % cat mapfile $mapfile_version 2 STUB_OBJECT; SYMBOL_SCOPE { _idx5 { ASSERT { TYPE=data; SIZE=4[5] }; }; idx5 { ASSERT { BINDING=weak; ALIAS=_idx5 }; }; idx5_func; local: *; }; The following main program is used to print all the index values available from the idx5 shared object. % cat main.c #include <stdio.h> extern int _idx5[5], idx5[5], idx5_func(int); int main(int argc, char **argv) { int i; for (i = 0; i The following commands create a stub version of this shared object in a subdirectory named stublib. elfdump is used to verify that the resulting object is a stub. The command used to build the stub differs from that of the real object only in the addition of the -z stub option, and the use of a different output file name. This demonstrates the ease with which stub generation can be added to an existing makefile. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o stublib/libidx5.so.1 -zstub % ln -s libidx5.so.1 stublib/libidx5.so % elfdump -d stublib/libidx5.so | grep STUB [11] FLAGS_1 0x4000000 [ STUB ] The main program can now be built, using the stub object to stand in for the real shared object, and setting a runpath that will find the real object at runtime. However, as we have not yet built the real object, this program cannot yet be run. Attempts to cause the system to load the stub object are rejected, as the runtime linker knows that stub objects lack the actual code and data found in the real object, and cannot execute. % cc main.c -L stublib -R '$ORIGIN/lib' -lidx5 -lc % ./a.out ld.so.1: a.out: fatal: libidx5.so.1: open failed: No such file or directory Killed % LD_PRELOAD=stublib/libidx5.so.1 ./a.out ld.so.1: a.out: fatal: stublib/libidx5.so.1: stub shared object cannot be used at runtime Killed We build the real object using the same command as we used to build the stub, omitting the -z stub option, and writing the results to a different file. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o lib/libidx5.so.1 Once the real object has been built in the lib subdirectory, the program can be run. % ./a.out [0] 0 0 0 [1] 1 1 1 [2] 2 2 2 [3] 3 3 3 [4] 4 4 4 Mapfile Changes The version 2 mapfile syntax was extended in a number of places to accommodate stub objects. Conditional Input The version 2 mapfile syntax has the ability conditionalize mapfile input using the $if control directive. As you might imagine, these directives are used frequently with ASSERT directives for data, because a given data symbol will frequently have a different size in 32 or 64-bit code, or on differing hardware such as x86 versus sparc. The link-editor maintains an internal table of names that can be used in the logical expressions evaluated by $if and $elif. At startup, this table is initialized with items that describe the class of object (_ELF32 or _ELF64) and the type of the target machine (_sparc or _x86). We found that there were a small number of cases in the Solaris code base in which we needed to know what kind of object we were producing, so we added the following new predefined items in order to address that need: NameMeaning ...... _ET_DYNshared object _ET_EXECexecutable object _ET_RELrelocatable object ...... STUB_OBJECT Directive The new STUB_OBJECT directive informs the link-editor that the object described by the mapfile can be built as a stub object. STUB_OBJECT; A stub shared object is built entirely from the information in the mapfiles supplied on the command line. When the -z stub option is specified to build a stub object, the presence of the STUB_OBJECT directive in a mapfile is required, and the link-editor uses the information in symbol ASSERT attributes to create global symbols that match those of the real object. When the real object is built, the presence of STUB_OBJECT causes the link-editor to verify that the mapfiles accurately describe the real object interface, and that a stub object built from them will provide the same linking interface as the real object it represents. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data in the object is required to have an ASSERT attribute that specifies the symbol type and size. If the ASSERT BIND attribute is not present, the link-editor provides a default assertion that the symbol must be GLOBAL. If the ASSERT SH_ATTR attribute is not present, or does not specify that the section is one of BITS or NOBITS, the link-editor provides a default assertion that the associated section is BITS. All data symbols that describe the same address and size are required to have ASSERT ALIAS attributes specified in the mapfile. If aliased symbols are discovered that do not have an ASSERT ALIAS specified, the link fails and no object is produced. These rules ensure that the mapfiles contain a description of the real shared object's linking interface that is sufficient to produce a stub object with a completely compatible linking interface. SYMBOL_SCOPE/SYMBOL_VERSION ASSERT Attribute The SYMBOL_SCOPE and SYMBOL_VERSION mapfile directives were extended with a symbol attribute named ASSERT. The syntax for the ASSERT attribute is as follows: ASSERT { ALIAS = symbol_name; BINDING = symbol_binding; TYPE = symbol_type; SH_ATTR = section_attributes; SIZE = size_value; SIZE = size_value[count]; }; The ASSERT attribute is used to specify the expected characteristics of the symbol. The link-editor compares the symbol characteristics that result from the link to those given by ASSERT attributes. If the real and asserted attributes do not agree, a fatal error is issued and the output object is not created. In normal use, the link editor evaluates the ASSERT attribute when present, but does not require them, or provide default values for them. The presence of the STUB_OBJECT directive in a mapfile alters the interpretation of ASSERT to require them under some circumstances, and to supply default assertions if explicit ones are not present. See the definition of the STUB_OBJECT Directive for the details. When the -z stub command line option is specified to build a stub object, the information provided by ASSERT attributes is used to define the attributes of the global symbols provided by the object. ASSERT accepts the following: ALIAS Name of a previously defined symbol that this symbol is an alias for. An alias symbol has the same type, value, and size as the main symbol. The ALIAS attribute is mutually exclusive to the TYPE, SIZE, and SH_ATTR attributes, and cannot be used with them. When ALIAS is specified, the type, size, and section attributes are obtained from the alias symbol. BIND Specifies an ELF symbol binding, which can be any of the STB_ constants defined in <sys/elf.h>, with the STB_ prefix removed (e.g. GLOBAL, WEAK). TYPE Specifies an ELF symbol type, which can be any of the STT_ constants defined in <sys/elf.h>, with the STT_ prefix removed (e.g. OBJECT, COMMON, FUNC). In addition, for compatibility with other mapfile usage, FUNCTION and DATA can be specified, for STT_FUNC and STT_OBJECT, respectively. TYPE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SH_ATTR Specifies attributes of the section associated with the symbol. The section_attributes that can be specified are given in the following table: Section AttributeMeaning BITSSection is not of type SHT_NOBITS NOBITSSection is of type SHT_NOBITS SH_ATTR is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SIZE Specifies the expected symbol size. SIZE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. The syntax for the size_value argument is as described in the discussion of the SIZE attribute below. SIZE The SIZE symbol attribute existed before support for stub objects was introduced. It is used to set the size attribute of a given symbol. This attribute results in the creation of a symbol definition. Prior to the introduction of the ASSERT SIZE attribute, the value of a SIZE attribute was always numeric. While attempting to apply ASSERT SIZE to the objects in the Solaris ON consolidation, I found that many data symbols have a size based on the natural machine wordsize for the class of object being produced. Variables declared as long, or as a pointer, will be 4 bytes in size in a 32-bit object, and 8 bytes in a 64-bit object. Initially, I employed the conditional $if directive to handle these cases as follows: $if _ELF32 foo { ASSERT { TYPE=data; SIZE=4 } }; bar { ASSERT { TYPE=data; SIZE=20 } }; $elif _ELF64 foo { ASSERT { TYPE=data; SIZE=8 } }; bar { ASSERT { TYPE=data; SIZE=40 } }; $else $error UNKNOWN ELFCLASS $endif I found that the situation occurs frequently enough that this is cumbersome. To simplify this case, I introduced the idea of the addrsize symbolic name, and of a repeat count, which together make it simple to specify machine word scalar or array symbols. Both the SIZE, and ASSERT SIZE attributes support this syntax: The size_value argument can be a numeric value, or it can be the symbolic name addrsize. addrsize represents the size of a machine word capable of holding a memory address. The link-editor substitutes the value 4 for addrsize when building 32-bit objects, and the value 8 when building 64-bit objects. addrsize is useful for representing the size of pointer variables and C variables of type long, as it automatically adjusts for 32 and 64-bit objects without requiring the use of conditional input. The size_value argument can be optionally suffixed with a count value, enclosed in square brackets. If count is present, size_value and count are multiplied together to obtain the final size value. Using this feature, the example above can be written more naturally as: foo { ASSERT { TYPE=data; SIZE=addrsize } }; bar { ASSERT { TYPE=data; SIZE=addrsize[5] } }; Exported Global Data Is Still A Bad Idea As you can see, the additional plumbing added to the Solaris link-editor to support stub objects is minimal. Furthermore, about 90% of that plumbing is dedicated to handling global data. We have long advised against global data exported from shared objects. There are many ways in which global data does not fit well with dynamic linking. Stub objects simply provide one more reason to avoid this practice. It is always better to export all data via a functional interface. You should always hide your data, and make it available to your users via a function that they can call to acquire the address of the data item. However, If you do have to support global data for a stub, perhaps because you are working with an already existing object, it is still easilily done, as shown above. Oracle does not like us to discuss hypothetical new features that don't exist in shipping product, so I'll end this section with a speculation. It might be possible to do more in this area to ease the difficulty of dealing with objects that have global data that the users of the library don't need. Perhaps someday... Conclusions It is easy to create stub objects for most objects. If your library only exports function symbols, all you have to do to build a faithful stub object is to add STUB_OBJECT; and then to use the same link command you're currently using, with the addition of the -z stub option. Happy Stubbing!

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• Podcast Show Notes: William Ulrich and Neal McWhorter on Business Architecture

  - by Bob Rhubart

  The latest ArchBeat podcast program features a four-part conversation with William Ulrich and Neal McWhorter, the authors of Business Architecture: The Art and Practice of Business Transformation, available from Meghan-Kiffer Press. Listen to Part 1 Bill and Neal cover the basics and discuss the effects of the lack of business architecture on organizations. Listen to Part 2 (Jan 19) What really happens to the billions of dollars annually invested in IT. Listen to Part 3 (Jan 26) Why the IT and business sides of many organizations can’t play nice. Listen to Part 4 (Feb 2) How IT architects and business architects can work together to get the ship back on course and keep it there. Connect William Ulrich Website | LinkedIn | Business Architecture Guild Neal McWhorter Website | LinkedIn | Business Architecture Group on OMG Coming Soon Bob Hensle, Director, Oracle Enterprise Architecture Group, discusses the recently launched IT Solutions from Oracle (ITSO) library of documents. Excerpts from a recent OTN Architect Community Virtual Meet-up. Stay tuned: RSS del.icio.us Tags: business architecture,enterprise architecture,arch2arch,archbeat,podcast,business transformation,oracle,oracle technology network Technorati Tags: business architecture,enterprise architecture,arch2arch,archbeat,podcast,business transformation,oracle,oracle technology network

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• Do 2D games have a future? [closed]

  - by Griffin

  I'm currently working on a 2D soft-body physics engine (since none exist right now -_-), but I'm worried that there's no point to spending what will most likely be years on it. Although I love working on it, I doubt such an engine would get any income considering anyone willing to pay money for the library will likely to be working in 3D. Do 2D games have any sort of future in the game industry? Should I just drop my engine and find something meaningful to work on? Bonus: I've been trying to think of a unique way to implement my physics engine in a 2d game by looking at games that are multiple dimensions, but still in 2d perspective like Paper Mario. Any ideas?

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• Alternative to pyGame ?

  - by stighy

  Hi, i'm learning something about game programming from a book about "pyGame". pyGame is simple, but... python is a little complex and different from my previous knoweledge about programming. I know "classical" language: C# (also C/C++), Java ... I know a lot of people love Python but for me is a little harder to learn! So i'm looking something like "pyGame" but for java or for c# ... A library with which i can do almost the same thing i can do with pygame (so .. do more with less code ... and headhace). Thank you Ps: excuse my "poor" english!

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• Java doesn't show up in firefox plugins

  - by user857990

  I've just installed the newest java, because firefox blocks the old version. I used the tutorial from http://www.backtrack-linux.org/wiki/index.php/Java_Install Because I had some trouble once, I knew that there are multiple library folders, so I linked into all mozilla plugin folders that there are. /root/.mozilla/plugins /usr/lib/firefox/plugins/ /usr/lib/firefox-addons /usr/lib/mozilla/plugins /usr/lib64/mozilla/plugins java -version returns java version "1.7.0_07" Java(TM) SE Runtime Environment (build 1.7.0_07-b10) Java HotSpot(TM) 64-Bit Server VM (build 23.3-b01, mixed mode) But when I go to firefox plugins, it's not listed. What do I need to do, so that firefox recognizes java?

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• How to become a more organized programmer?

  - by Ted Wong

  I am a programmer that can code. But I find that I can get thing done, but not get thing do well or like most of the open source communities do. Well, I use some of the library from git hub. I find most of the programme is well structure. Also, a read me. My question are: Is that any common file structure or naming convention in the community or this is just a matter of personal taste? How to become a more organized programmer, instead of writing code just work. But more organized that let other easy to get in your project?

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• 2D Physics Engine to Handle Shapes Composed of Multiple Densities XNA

  - by Stupac

  The game I'm working on involves shapes that might be composed of multiple materials in a variety of ways. Let's just take for example a wooden rod with and sizable tip of iron or say a block composed of a couple triangles of stone and aluminum and small nugget of gold. The shapes and compositions will change from time to time, so I was wondering what engine I should use and how I might implement this feature? I've looked at Farseer 3, but I'm still trying to decipher the library by reading the source and the samples and wasn't sure if I was barking up the wrong tree. Thanks!

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• Different callbacks for error or error as first argument?

  - by Florian Margaine

  We (and the JS SO chat room) had a talk with @rlemon some days ago about his Little-XHR library about error handling. Basically, we wanted to decide which error handling pattern should be used: xhr.get({ // Some parameters, and then success: function(data) {}, failure: function(data) {} }) Or: xhr.get({ // Some parameters, and then callback: function(err, data) {} }) One is more jQuery-like, while the other is more Node-like. Some say that the first pattern makes you think more about handling error. I think the opposite, since you may forget the other callback function, while the argument is always there on the second pattern. Any opinion/advantage/drawback about both these patterns?

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• Article about Sun ZFS Storage Appliances

  - by Owen Allen

  Sun ZFS Storage Appliances are versatile storage systems. Discovering and managing them in Ops Center, though, makes them even more versatile. If you discover a Sun ZFS Storage Appliance in Ops Center 12c, you can create iSCSI and Fibre Channel LUNS, and make the LUNs available to server pools and virtualization hosts as a storage library. Barbara Higgins has written an excellent article that walks you through the process of setting up a Sun ZFS Storage Appliance and discovering and managing it in Ops Center. If you're looking into ways to make a Sun ZFS Storage Appliance work for you, it's worth a look.

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• Developing for iOS on Linux

  - by Jay

  I am looking for an engine or library to develop a game for iOS on Linux. High level, low level, GUI, no GUI, does not matter too much. I am really looking for anything. I'm not actually talking about deploying to iOS from Linux or anything like. I just want to do the bulk of the work on Linux, with minimal changes required to run it on iOS. Edit: YES, I do have access to a Mac, but it is limited. So I want to be able to work on the project on my regular Ubuntu box. Also, I am in the paid developer program, so I can deploy to iOS devices from the Mac.

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• What is this code?

  - by Aerovistae

  This is from the Evolution of a Programmer "joke", at the "Master Programmer" level. It seems to be C++, but I don't know what all this bloated extra stuff is, nor did any Google searches turn up anything except the joke I took it from. Can anyone tell me more about what I'm reading here? [ uuid(2573F8F4-CFEE-101A-9A9F-00AA00342820) ] library LHello { // bring in the master library importlib("actimp.tlb"); importlib("actexp.tlb"); // bring in my interfaces #include "pshlo.idl" [ uuid(2573F8F5-CFEE-101A-9A9F-00AA00342820) ] cotype THello { interface IHello; interface IPersistFile; }; }; [ exe, uuid(2573F890-CFEE-101A-9A9F-00AA00342820) ] module CHelloLib { // some code related header files importheader(<windows.h>); importheader(<ole2.h>); importheader(<except.hxx>); importheader("pshlo.h"); importheader("shlo.hxx"); importheader("mycls.hxx"); // needed typelibs importlib("actimp.tlb"); importlib("actexp.tlb"); importlib("thlo.tlb"); [ uuid(2573F891-CFEE-101A-9A9F-00AA00342820), aggregatable ] coclass CHello { cotype THello; }; }; #include "ipfix.hxx" extern HANDLE hEvent; class CHello : public CHelloBase { public: IPFIX(CLSID_CHello); CHello(IUnknown *pUnk); ~CHello(); HRESULT __stdcall PrintSz(LPWSTR pwszString); private: static int cObjRef; }; #include <windows.h> #include <ole2.h> #include <stdio.h> #include <stdlib.h> #include "thlo.h" #include "pshlo.h" #include "shlo.hxx" #include "mycls.hxx" int CHello:cObjRef = 0; CHello::CHello(IUnknown *pUnk) : CHelloBase(pUnk) { cObjRef++; return; } HRESULT __stdcall CHello::PrintSz(LPWSTR pwszString) { printf("%ws\n", pwszString); return(ResultFromScode(S_OK)); } CHello::~CHello(void) { // when the object count goes to zero, stop the server cObjRef--; if( cObjRef == 0 ) PulseEvent(hEvent); return; } #include <windows.h> #include <ole2.h> #include "pshlo.h" #include "shlo.hxx" #include "mycls.hxx" HANDLE hEvent; int _cdecl main( int argc, char * argv[] ) { ULONG ulRef; DWORD dwRegistration; CHelloCF *pCF = new CHelloCF(); hEvent = CreateEvent(NULL, FALSE, FALSE, NULL); // Initialize the OLE libraries CoInitiali, NULL); // Initialize the OLE libraries CoInitializeEx(NULL, COINIT_MULTITHREADED); CoRegisterClassObject(CLSID_CHello, pCF, CLSCTX_LOCAL_SERVER, REGCLS_MULTIPLEUSE, &dwRegistration); // wait on an event to stop WaitForSingleObject(hEvent, INFINITE); // revoke and release the class object CoRevokeClassObject(dwRegistration); ulRef = pCF->Release(); // Tell OLE we are going away. CoUninitialize(); return(0); } extern CLSID CLSID_CHello; extern UUID LIBID_CHelloLib; CLSID CLSID_CHello = { /* 2573F891-CFEE-101A-9A9F-00AA00342820 */ 0x2573F891, 0xCFEE, 0x101A, { 0x9A, 0x9F, 0x00, 0xAA, 0x00, 0x34, 0x28, 0x20 } }; UUID LIBID_CHelloLib = { /* 2573F890-CFEE-101A-9A9F-00AA00342820 */ 0x2573F890, 0xCFEE, 0x101A, { 0x9A, 0x9F, 0x00, 0xAA, 0x00, 0x34, 0x28, 0x20 } }; #include <windows.h> #include <ole2.h> #include <stdlib.h> #include <string.h> #include <stdio.h> #include "pshlo.h" #include "shlo.hxx" #include "clsid.h" int _cdecl main( int argc, char * argv[] ) { HRESULT hRslt; IHello *pHello; ULONG ulCnt; IMoniker * pmk; WCHAR wcsT[_MAX_PATH]; WCHAR wcsPath[2 * _MAX_PATH]; // get object path wcsPath[0] = '\0'; wcsT[0] = '\0'; if( argc > 1) { mbstowcs(wcsPath, argv[1], strlen(argv[1]) + 1); wcsupr(wcsPath); } else { fprintf(stderr, "Object path must be specified\n"); return(1); } // get print string if(argc > 2) mbstowcs(wcsT, argv[2], strlen(argv[2]) + 1); else wcscpy(wcsT, L"Hello World"); printf("Linking to object %ws\n", wcsPath); printf("Text String %ws\n", wcsT); // Initialize the OLE libraries hRslt = CoInitializeEx(NULL, COINIT_MULTITHREADED); if(SUCCEEDED(hRslt)) { hRslt = CreateFileMoniker(wcsPath, &pmk); if(SUCCEEDED(hRslt)) hRslt = BindMoniker(pmk, 0, IID_IHello, (void **)&pHello); if(SUCCEEDED(hRslt)) { // print a string out pHello->PrintSz(wcsT); Sleep(2000); ulCnt = pHello->Release(); } else printf("Failure to connect, status: %lx", hRslt); // Tell OLE we are going away. CoUninitialize(); } return(0); }

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• How can architects work with self-organizing Scrum teams?

  - by Martin Wickman

  An organization with a number of agile Scrum teams also has a small group of people appointed as "enterprise architects". The EA group acts as control and gatekeeper for quality and adherence to decisions. This leads to overlaps between the team decision and EA decisions. For instance, the team might want to use library X or want to use REST instead of SOAP, but the EA does not approve of that. Now, this can lead to frustration when team decisions are overruled. Taken far enough, it can potentially lead to a situation where the EA people "grabs" all power and the team ends up feeling demotivated and not very agile at all. The Scrum guides has this to say about it: Self-organizing: No one (not even the Scrum Master) tells the Development Team how to turn Product Backlog into Increments of potentially releasable functionality. Is that reasonable? Should the EA team be disbanded? Should the teams refuse or simply comply?

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• How to Sync Your Media Across Your Entire House with XBMC

  - by Jason Fitzpatrick

  XBMC is an awesome media center solution but when you’re using it all over your house your library updates and watched-media lists get out of sync. Read on as we show how to keep all your media centers on the same page. Note: This how-to guide was originally published in September of 2011 and detailed how to set up whole-house media syncing for XBMC “Dharma” 10.0. We’ve updated the guide for the newer, more user-friendly MySQL integration included in XBMC “Eden” 11.0.  How to Sync Your Media Across Your Entire House with XBMC How to Own Your Own Website (Even If You Can’t Build One) Pt 2 How to Own Your Own Website (Even If You Can’t Build One) Pt 1

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• Visual Studio Async CTP

  - by Daniel Moth

  While most of the buzz at the recent PDC here at Microsoft's headquarters has been about Windows Azure and Windows Phone, there is a truly noteworthy technology that as a .NET developer (of any kind of application) you should pay attention to, even in its early technology preview stage: Visual Studio Async CTP. I could provide many more direct links, but you do not need them: just visit the home page of this technology to download whitepapers, watch videos on how this technology integrates with C# and with VB, (through the new async and await language keywords) as well as videos on how the technology works under the covers (based largely on the Task Parallel Library). More importantly, download the actual bits (they install on top of your Visual Studio 2010), which include many samples. Get ready for a revolution in Asynchronous Programming with C# and Visual Basic. Comments about this post welcome at the original blog.

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• How to Use Steam In-Home Streaming

  - by Chris Hoffman

  Steam’s In-Home Streaming is now available to everyone, allowing you to stream PC games from one PC to another PC on the same local network. Use your gaming PC to power your laptops and home theater system. This feature doesn’t allow you to stream games over the Internet, only the same local network. Even if you tricked Steam, you probably wouldn’t get good streaming performance over the Internet. Why Stream? When you use Steam In-Home streaming, one PC sends its video and audio to another PC. The other PC views the video and audio like it’s watching a movie, sending back mouse, keyboard, and controller input to the other PC. This allows you to have a fast gaming PC power your gaming experience on slower PCs. For example, you could play graphically demanding games on a laptop in another room of your house, even if that laptop has slower integrated graphics. You could connect a slower PC to your television and use your gaming PC without hauling it into a different room in your house. Streaming also enables cross-platform compatibility. You could have a Windows gaming PC and stream games to a Mac or Linux system. This will be Valve’s official solution for compatibility with old Windows-only games on the Linux (Steam OS) Steam Machines arriving later this year. NVIDIA offers their own game streaming solution, but it requires certain NVIDIA graphics hardware and can only stream to an NVIDIA Shield device. How to Get Started In-Home Streaming is simple to use and doesn’t require any complex configuration — or any configuration, really. First, log into the Steam program on a Windows PC. This should ideally be a powerful gaming PC with a powerful CPU and fast graphics hardware. Install the games you want to stream if you haven’t already — you’ll be streaming from your PC, not from Valve’s servers. (Valve will eventually allow you to stream games from Mac OS X, Linux, and Steam OS systems, but that feature isn’t yet available. You can still stream games to these other operating systems.) Next, log into Steam on another computer on the same network with the same Steam username. Both computers have to be on the same subnet of the same local network. You’ll see the games installed on your other PC in the Steam client’s library. Click the Stream button to start streaming a game from your other PC. The game will launch on your host PC, and it will send its audio and video to the PC in front of you. Your input on the client will be sent back to the server. Be sure to update Steam on both computers if you don’t see this feature. Use the Steam > Check for Updates option within Steam and install the latest update. Updating to the latest graphics drivers for your computer’s hardware is always a good idea, too. Improving Performance Here’s what Valve recommends for good streaming performance: Host PC: A quad-core CPU for the computer running the game, minimum. The computer needs enough processor power to run the game, compress the video and audio, and send it over the network with low latency. Streaming Client: A GPU that supports hardware-accelerated H.264 decoding on the client PC. This hardware is included on all recent laptops and PCs. Ifyou have an older PC or netbook, it may not be able to decode the video stream quickly enough. Network Hardware: A wired network connection is ideal. You may have success with wireless N or AC networks with good signals, but this isn’t guaranteed. Game Settings: While streaming a game, visit the game’s setting screen and lower the resolution or turn off VSync to speed things up. In-Home Steaming Settings: On the host PC, click Steam > Settings and select In-Home Streaming to view the In-Home Streaming settings. You can modify your streaming settings to improve performance and reduce latency. Feel free to experiment with the options here and see how they affect performance — they should be self-explanatory. Check Valve’s In-Home Streaming documentation for troubleshooting information. You can also try streaming non-Steam games. Click Games > Add a Non-Steam Game to My Library on your host PC and add a PC game you have installed elsewhere on your system. You can then try streaming it from your client PC. Valve says this “may work but is not officially supported.” Image Credit: Robert Couse-Baker on Flickr, Milestoned on Flickr

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• Which simple Java JPA ORM tool to use ?

  - by Guillaume

  What Java ORM library implementing JPA that match following criteria would you recommend and why ? free & open source alive (at least bug fixes and a mailing list) with good documentation simple not hibernate (this one is well-known :-) ) I need to select a simple ORM tool that can be set up in minutes without and easy to understand for setting simple CRUD daos. A query builder ill be an interesting plus. Later I can have to move to Hibernate, that's why being JPA compliant is a must. I have found some candidates on the web, but not so much feedback, so I will gladly take your advices on the topic. ----- EDIT --------- I have been successfully testing ebean/avaje with a small test cases. Any one has a feedback on using this tool in production ?

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• clicktale.com alternative that works with https and ajax

  - by Alexey Ivanov

  I need to record user's actions on site for analytics purposes. The way clicktale.com doing it is just fine. But unfortunately it have problems with working over https and recording ajax events. Is there some service or script/library that I can host that can do this task? Non-free one's are ok to. Clarification: ClickTale function that I want to reproduce is recording of separate user sessions and their replay. So you can see video of all user's interactions with page: There he clicks first, which links opens, etc. Usually such services replay user's actions buy reproducing them with javascript (and here comes ajax problem: external sites can't use ajax because of cross-domain scripting). So I'm looking for a tool (possibly script that I host on site to allow cross-domain scripting) that can record ajax blocks actions.

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• Performance tuning of tabular data models in Analysis Services

  - by Greg Low

  More and more practical information around working with tabular data models is starting to appear as more and more sites get deployed.At SQL Down Under, we've already helped quite a few customers move to tabular data models in Analysis Services and have started to collect quite a bit of information on what works well (and what doesn't) in terms of performance of these models. We've also been running a lot of training on tabular data models.It was great to see a whitepaper on the performance of these models released today.Performance Tuning of Tabular Models in SQL Server 2012 Analysis Services was written by John Sirmon, Greg Galloway, Cindy Gross and Karan Gulati. You'll find it here: http://msdn.microsoft.com/en-us/library/dn393915.aspx

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• 2010 FIFA World Cup Silverlight Smooth Streaming Player with Live Messenger

  - by FernandoCortes

  Finally after weeks of hard work the World Cup Silverlight player is ready to watch the spanish team in action. This Silverlight Player use Smooth Streaming technology, enables adaptive streaming of media to Silverlight and other clients over HTTP. Smooth Streaming provides a high-quality viewing experience that scales massively on content distribution networks, making true HD 1080p media experiences a reality. The player integrate leading social networks such as Microsoft Live Messenger, Twitter and Facebook to chat in a public chat and with your Windows Live Messenger contacts list completely private. All supported on Microsoft Azure in one of the biggest deployments in this platform (350 instances). We integrate Windows Live Messenger with Siverlight using the javascript messenger library, version 3.5. Check out this video, in spanish, where Antón and me explain how to integrate Silverlight and Live Messenger: http://www.channels.com/episodes/show/8900143/-Codecamp-es-2009-Messenger-Cortes-Molleda   Player Uri http://mundial2010.telecinco.es/ (Spanish Television)   Developer & Design Team Antón Molleda (Developer) Luis Guerrero (Developer) Raúl Varela (Designer) Ricardo Acosta (Designer) Fernando Cortés Hierro (myself)

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• Adding Async=true to the page- no side effects noticed.

  - by Michael Freidgeim

  Recently I needed to implement PageAsyncTask  in .Net 4 web forms application.According to http://msdn.microsoft.com/en-us/library/system.web.ui.pageasynctask.aspx"A PageAsyncTask object must be registered to the page through the RegisterAsyncTask method. The page itself does not have to be processed asynchronously to execute asynchronous tasks. You can set the Async attribute to either true (as shown in the following code example) or false on the page directive and the asynchronous tasks will still be processed asynchronously:<%@ Page Async="true" %>When the Async attribute is set to false, the thread that executes the page will be blocked until all asynchronous tasks are complete."I was worry about any site effects if I will set  Async=true on the existing page.The only documented restrictions, that I found are that@Async is not compatible with @AspCompat and Transaction attributes (from @ Page directive  MSDN article). In other words, Asynchronous pages do not work when the AspCompat attribute is set to true or the Transactionattribute is set to a value other than Disabled in the @ Page directiveFrom our tests we conclude, that adding Async=true to the page is quite safe, even if you don't always call Async tasks from the page

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• No audio flash movies

  - by Valerio Giuffrida

  I've installed natty a few days ago and I'm experience some issues with the audio. Basically, I'm not able to listen anything coming from flash movies (such as youtube). This happen with both chromium and firefox (I use only the first one) and the errore I get in the stdout is: ALSA lib pcm.c:2109:(snd_pcm_open_conf) Cannot open shared library /usr/lib/alsa-lib/libasound_module_pcm_pulse.so I don't know how to fix it. I found somewhere to install native x64 flash plugins, but somebody says it is not advisable. I didn't get this kind of issues with 10.10 I've gotten before of natty. Hence, what am I supposed to do? thank you very much

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• Caching large amount of ajax returned objects

  - by ofcapl

  I'm building an application which fetches large amount of items with ajax requests via other application API. It returns me 6k - 30k js objects which are used multiple times across various application views (sorting, filtering etc.). I would like to avoid querying API every time for such big list so I decided to cache this data somehow. I was thinking about various solutions: saving it to localstorage, using some caching library (e.g. locachejs), storing in js var. I'm not an expert so I would like to hear Your suggestions about each (or one of these) solution, about its pros and cons. Every help will be very appreciated.

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• How to Draw texture between 2 Vector3

  - by Sparky41

  My scenario: RTS combat style, 1 unit fires beam on another unit My problem is i want to draw a flat texture between 2 Vector3 points. I have looked at various Billboarding styles but that doesn't give me a proper solution. I looked at this: http://msdn.microsoft.com/en-us/library/bb464051.aspx is BasicEffect and DrawPrimitives the correct solution just stretch the texture to the distance between point of origin to target? I used the quad class they used but i found this it seemed to inflexible So my question to you is how would i go about this sort of problem? Regards

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