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• resources for embedded projects

  - by osum

  Can anyone suggest links/resources for sample project implementations of embedded projects using c++ or gcc.

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• Protobuf compiler for several languages

  - by Stipa

  Hi, In my project I have components written on Python, ObjectiveC and J2ME. I want to use protobuf as data interchange format. However, there are one issue I need to resolve. Google implementation doesn't support ObjC and J2ME. There are 3rd party implementations that supports those languages. But I really don't want to be depended of several protoc implementations. What is the best way for me to have protobufs for several languages? Do I need to use different compilers or there is other option? Thanks, -Lev

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• Alternatives libraries for loading PNG images

  - by Robert

  My java J2SE application is reading a lot of (png) images from the web and some of them use features such as a transparency color for true-color images (tRNS section) that Sun's/Oracle's PNGImageReader implementation simply ignores. Therefore the common solution for loading via ImageIO.read(...); does not work for me as it relies on this incomplete PNGImageReader implementation. Does anybody know a png reader implementation that can read all forms of PNG images correctly - those with color table or true-color and alpha transparency or transparent color? As it is for a GPL project it should be a non-commercial one that can be included without licensing problems into the app. Edit: My be this question was too specific. Therefore let be redesign my question: Who knows alternative implementations and libraries that are able to load PNG files? I will then test the implementations for their capabilities to load some test png images. Edit2: The end result have to be a BufferedImage

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• Are self-described / auto-descriptive services loosely or tightly coupled in a SOA architecture ?

  - by snowflake

  I consider a self-described / auto-descriptive service as a good thing in a SOA architecture, since (almost) everything you know to call the service is present in the service contract (such a WSDL). Sample of a non self-described service for me is Facebook Query Language (FQL http://wiki.developers.facebook.com/index.php/FQL), or any web service exchanging XML flow in a one String parameter for then parsing XML and performing treatments. Last ones seem further more technically decoupled, since technically you can switch implementations without technical impact on the caller, handling compatibility between implementations/versions at a business level. On the other side, having no strong interface (diluted into the service and its version), make the service tightly coupled to the existing implementation (more difficulty to interchange the service and to ensure perfect compatibility). This question is related to http://stackoverflow.com/questions/2503071/how-to-implement-loose-coupling-with-a-soa-architecture So, are self-described / auto-descriptive services loosely or tightly coupled in a SOA architecture ? What are the impacts regarding ESBs ? Any pointer will be appreciated.

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• Correct syntax of a HTTP 100 Continue response

  - by PartlyCloudy

  For me, one of the weakest points of the HTTP 1.1 RFC and the various implementations around is how to deal with 100 Continue headers. I searched on the web for a while and had a look at different implementations. However, there is one thing I'm not sure of. what is the correct syntax of a 100 Continue message? Several sources claim, that this must be a single response line without any further header lines. However, I can't find that in the RFC 2616 reflected. So what is right? HTTP/1.1 100 Continue or HTTP/1.1 100 Continue [Additional Headers…] ?

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• Which libraries use the "We Know Where You Live" optimization for std::make_shared?

  - by KnowItAllWannabe

  Over two years ago, Stephan T. Lavavej described a space-saving optimization he implemented in Microsoft's implementation of std::make_shared, and I know from speaking with him that Microsoft has nothing against other library implementations adopting this optimization. If you know for sure whether other libraries (e.g., for Gnu C++, Clang, Intel C++, plus Boost (for boost::make_shared)) have adopted this implementation, please contribute an answer. I don't have ready access to that many make_shared implementations, nor am I wild about digging into the bowels of the ones I have to see if they've implemented the WKWYL optimization, but I'm hoping that SO readers know the answers for some libraries off-hand. I know from looking at the code that as of Boost 1.52, the WKWYL optimization had not been implemented, but Boost is now up to version 1.55. Note that this optimization is different from std::make_shared's ability to avoid a dedicated heap allocation for the reference count used by std::shared_ptr. For a discussion of the difference between WKWYL and that optimication, consult this question.

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• C++ Virtual keyword as away to avoid including code units.

  - by user394663

  Currently we have a body of code that allows service plugins which offer forms of communication to the core e.g tcp/ip, udp/ip, usb, etc... These service plugins feedback notifier class instances to the core for further processing. In the current implementation a service project (which is a separate dynamically linked library brought in at runtime by the core via dlopen and friends) will compile against the notifier.cpp file that resides in the core source code (a separate project). This gives access to the notifiers method implementations. This works perfectly no complaints. Two alternative options: 1. put the notifier method implementations in the header file. 2. declare the notifier methods virtual and delay binding until runtime. Avoiding the issues of computational overhead what are the impacts of option 2? Are there any other options available to us? Thanks

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• Passing around objects to network packet handlers ?

  - by xeross

  Hey, I've been writing a networking server for a while now in C++ and have come to the stage to start looking for a way to properly and easily handle all packets. I am so far that I can figure out what kind of packet it is, but now I need to figure out how to get the needed data to the handler functions. I had the following in mind: Have a map of function pointers with the opcode as key and the function pointer as value Have all these functions have 2 arguments, packet and ObjectAccessor ObjectAccessor class contains various functions to fetch various items such as users and alike Perhaps pass the user's guid too so we can fetch it from the objectaccessor I'd like to know the various implementations others have come up with, so please comment on this idea and reply with your own implementations. Thanks, Xeross

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• Handling a binary operation that makes sense only for part of a hierarchy.

  - by usersmarvin_

  I have a hierarchy, which I'll simplify greatly, of implementations of interface Value. Assume that I have two implementations, NumberValue, and StringValue. There is an average operation which only makes sense for NumberValue, with the signature NumberValue average(NumberValue numberValue){ ... } At some point after creating such variables and using them in various collections, I need to average a collection which I know is only of type NumberValue, there are three possible ways of doing this I think: Very complicated generic signatures which preserve the type info in compile time (what I'm doing now, and results in hard to maintain code) Moving the operation to the Value level, and: throwing an unsupportedOperationException for StringValue, and casting for NumberValue. Casting at the point where I know for sure that I have a NumberValue, using slightly less complicated generics to insure this. Does anybody have any better ideas, or a recommendation on oop best practices?

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• AppDomain assemblies not being loaded correctly.

  - by SharePoint Newbie

  Hi, We are doing the following in the Application_Start (Global.ascx.cs) for a WCF Service hosted by IIS 7.0 (integrated pipeline). var mapperConfigurations = AppDomain.CurrentDomain.GetAssemblies() .SelectMany(a => a.GetExportedTypes().Where(t => typeof (IMapperConfiguration).IsAssignableFrom(t) && t.IsClass)) .ToList(); The web-service has 8-10 assemblies in its bin folder and each of them have multiple implementations of IMapperConfiguration. After an IIS Reset, no mapper configurations are found (found this using debug.write). However, this behaviour is inconsistent and at other times all implementations of IMapperConfiguration are found. When exactly does IIS load assemblies and what is wrong with this code? Thanks

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• Is the situation with Java ME improving?

  - by mike g

  It seems to be the consensus that developing for Java ME is not as cross platform as you might expect, particularly compared to say java SE, but it is difficult to assess how the situation is evolving. Is the situation improving significantly? Are problematic implementations being patched? Are problematic implementations dying out as a proportion of mobile devices? Is the tool chain improving? Are there ways to identify at least some cross platform 'errors' without necessarily deploying to each and every device?

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• Reflection alternative for switch on enum in order to select namespace/class

  - by Am

  Hi, I have an interface named IHarvester. There are 3 implementations of that interface, each under their own namespace: Google Yahoo Bing A HarvesterManager uses the given harvester. It knows the interface and all 3 implementations. I want some way of letting the class user say in which harvester it wants to use. And in the code select that implementation, without a switch-case implementation. Can reflection save my day? Here is the code bits: // repeat for each harvester namespace Harvester.Google { public abstract class Fetcher : BaseHarvester, IInfoHarvester {...} } public enum HarvestingSource { Google, Yahoo, Bing, } class HarvesterManager { public HarvestingSource PreferedSource {get;set;} public HarvestSomthing() { switch (PreferedSource) .... // awful... } } Thanks. I will give my 2 cents of why I want to change this. There several people writing harvesters, I want them to focus only on building more harvesters, without ever needing to update the enum, or at worst, update only the enum.

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• [C++] Passing around objects to network packet handlers ?

  - by xeross

  Hey, I've been writing a networking server for a while now in C++ and have come to the stage to start looking for a way to properly and easily handle all packets. I am so far that I can figure out what kind of packet it is, but now I need to figure out how to get the needed data to the handler functions. I had the following in mind: Have a map of function pointers with the opcode as key and the function pointer as value Have all these functions have 2 arguments, packet and ObjectAccessor ObjectAccessor class contains various functions to fetch various items such as users and alike Perhaps pass the user's guid too so we can fetch it from the objectaccessor I'd like to know the various implementations others have come up with, so please comment on this idea and reply with your own implementations. Thanks, Xeross

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• C#: Converting string to namespace

  - by Am

  Hi, I have an interface named IHarvester. There are 3 implementations of that interface, each under their own namespace: Google Yahoo Bing A HarvesterManager uses the given harvester. It knows the interface and all 3 implementations. I want some way of letting the class user say in which harvester it wants to use. And in the code select that implementation, without a switch-case implementation. Can reflection save my day? Here is the code bits: // repeat for each harvester namespace Harvester.Google { public abstract class Fetcher : BaseHarvester, IInfoHarvester {...} } public enum HarvestingSource { Google, Yahoo, Bing, } class HarvesterManager { public HarvestingSource PreferedSource {get;set;} public HarvestSomthing() { switch (PreferedSource) .... // awful... } } Thanks.

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• Parallelism in .NET – Part 15, Making Tasks Run: The TaskScheduler

  - by Reed

  In my introduction to the Task class, I specifically made mention that the Task class does not directly provide it’s own execution.  In addition, I made a strong point that the Task class itself is not directly related to threads or multithreading.  Rather, the Task class is used to implement our decomposition of tasks.  Once we’ve implemented our tasks, we need to execute them.  In the Task Parallel Library, the execution of Tasks is handled via an instance of the TaskScheduler class. The TaskScheduler class is an abstract class which provides a single function: it schedules the tasks and executes them within an appropriate context.  This class is the class which actually runs individual Task instances.  The .NET Framework provides two (internal) implementations of the TaskScheduler class. Since a Task, based on our decomposition, should be a self-contained piece of code, parallel execution makes sense when executing tasks.  The default implementation of the TaskScheduler class, and the one most often used, is based on the ThreadPool.  This can be retrieved via the TaskScheduler.Default property, and is, by default, what is used when we just start a Task instance with Task.Start(). Normally, when a Task is started by the default TaskScheduler, the task will be treated as a single work item, and run on a ThreadPool thread.  This pools tasks, and provides Task instances all of the advantages of the ThreadPool, including thread pooling for reduced resource usage, and an upper cap on the number of work items.  In addition, .NET 4 brings us a much improved thread pool, providing work stealing and reduced locking within the thread pool queues.  By using the default TaskScheduler, our Tasks are run asynchronously on the ThreadPool. There is one notable exception to my above statements when using the default TaskScheduler.  If a Task is created with the TaskCreationOptions set to TaskCreationOptions.LongRunning, the default TaskScheduler will generate a new thread for that Task, at least in the current implementation.  This is useful for Tasks which will persist for most of the lifetime of your application, since it prevents your Task from starving the ThreadPool of one of it’s work threads. The Task Parallel Library provides one other implementation of the TaskScheduler class.  In addition to providing a way to schedule tasks on the ThreadPool, the framework allows you to create a TaskScheduler which works within a specified SynchronizationContext.  This scheduler can be retrieved within a thread that provides a valid SynchronizationContext by calling the TaskScheduler.FromCurrentSynchronizationContext() method. This implementation of TaskScheduler is intended for use with user interface development.  Windows Forms and Windows Presentation Foundation both require any access to user interface controls to occur on the same thread that created the control.  For example, if you want to set the text within a Windows Forms TextBox, and you’re working on a background thread, that UI call must be marshaled back onto the UI thread.  The most common way this is handled depends on the framework being used.  In Windows Forms, Control.Invoke or Control.BeginInvoke is most often used.  In WPF, the equivelent calls are Dispatcher.Invoke or Dispatcher.BeginInvoke. As an example, say we’re working on a background thread, and we want to update a TextBlock in our user interface with a status label.  The code would typically look something like: // Within background thread work... string status = GetUpdatedStatus(); Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action( () => { statusLabel.Text = status; })); // Continue on in background method .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This works fine, but forces your method to take a dependency on WPF or Windows Forms.  There is an alternative option, however.  Both Windows Forms and WPF, when initialized, setup a SynchronizationContext in their thread, which is available on the UI thread via the SynchronizationContext.Current property.  This context is used by classes such as BackgroundWorker to marshal calls back onto the UI thread in a framework-agnostic manner. The Task Parallel Library provides the same functionality via the TaskScheduler.FromCurrentSynchronizationContext() method.  When setting up our Tasks, as long as we’re working on the UI thread, we can construct a TaskScheduler via: TaskScheduler uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); We then can use this scheduler on any thread to marshal data back onto the UI thread.  For example, our code above can then be rewritten as: string status = GetUpdatedStatus(); (new Task(() => { statusLabel.Text = status; })) .Start(uiScheduler); // Continue on in background method This is nice since it allows us to write code that isn’t tied to Windows Forms or WPF, but is still fully functional with those technologies.  I’ll discuss even more uses for the SynchronizationContext based TaskScheduler when I demonstrate task continuations, but even without continuations, this is a very useful construct. In addition to the two implementations provided by the Task Parallel Library, it is possible to implement your own TaskScheduler.  The ParallelExtensionsExtras project within the Samples for Parallel Programming provides nine sample TaskScheduler implementations.  These include schedulers which restrict the maximum number of concurrent tasks, run tasks on a single threaded apartment thread, use a new thread per task, and more.

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• SOA &amp; E2.0 Partner Community Forum XIII registration is open

  - by Jürgen Kress

  INVITATION TO THE ORACLE SOA AND E2.0 PARTNER COMMUNITY FORUM Do you want to learn about how to sell the value of Fusion Middleware by combining SOA and E2.0 Solutions? We would like to invite you to become updated and trained at our SOA and E2.0 Partner Community Forum March on 15th and 16th 2011 in Utrecht, The Netherlands. Keynote: Andrew Sutherland and Andrew Gilboy The Oracle SOA and E2.0 Partner Community Forum is a wonderful opportunity to: learn how to sell the value of Fusion Middleware bij combining SOA and E2.0 solutions meet with Oracle SOA and E2.0 Product management exchange knowledge learn from successful SOA, BPM, WebCenter and UCM implementations understand Oracle's Fusion Applications Strategy network within the Oracle SOA Partner Community and the Oracle E2.0 Partner Community During this highly informative event you can learn about partner success stories, participate in an array of break out sessions, exchange information with other partners and enjoy a vibrant panel discussion. Additionally to the SOA and E2.0 Partner Community Forum, you can participate in technical hands on workshops on March 17th and 18th. The goal of these workshops is to prepare you for customer implementations. Places are limited, so don't delay and register now by clicking here. Registration takes a few minutes and is free of charge, except in case of cancellation or no show (cancellation fee € 150). For more information, please visit our website. Best regards Jürgen Kress & Hans Blaas SOA & E2.0 Partner Adoption EMEA Agenda March 15th 2011 Welcome & Introduction Keynote Oracle Middleware Strategy and information on Application Grid and Exalogic Andrew Sutherland, SVP Middleware Sales EMEA, Oracle Keynote Managing Online Customer, Partner and Employee Engagement with Oracle E2.0 Solutions Andrew Gilboy, VP E2.0 Sales EMEA, Oracle Partner SOA/BPM Reference Case Partner WebCenter/UCM Reference Case SOA Suite PS3 David Shaffer, VP Product Management, Oracle Why Specialization is important for Partners Nick Kritikos, Hans Blaas & Jürgen Kress, Alliances & Channels, Oracle   Agenda March 16th 2011 Welcome & Introduction Day II Breakout round 1 - SOA Suite 11g PS3 & OSB - Importance of ADF & JDeveloper - SOA Security IDM - WebCenter PS3, Whats new - E2.0 Sales Plays Breakout round 2 - WebCenter PS3, Whats new - Application Management Enterprise manager and Amberpoint - ADF/WebCenter 11g integration with BPM Suite 11g - Importance of ADF & JDeveloper - JCAPS & OC4J migration opportunities for service business Breakout round 3 - BPM 11g: Whats new - Universal Content management 11g - SOA Security Management - E2.0 Surrounding Products: ATG, Documaker, Primavera - Middleware Industry Value Propositions & Sales Play Fusion Application SOA & E2.0 Summary & Closing For registration and additional information, please visit our website. For more information on SOA Specialization and the SOA Partner Community please feel free to register at www.oracle.com/goto/emea/soa (OPN account required) Blog Twitter LinkedIn Mix Forum Wiki Website Technorati Tags: SOA Community,SOA,SOA Partner Community Forum,SOA Community Forum,OPN,Jürgen Kress

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• MAXDOP in SQL Azure

  - by Herve Roggero

  In my search of better understanding the scalability options of SQL Azure I stumbled on an interesting aspect: Query Hints in SQL Azure. More specifically, the MAXDOP hint. A few years ago I did a lot of analysis on this query hint (see article on SQL Server Central:  http://www.sqlservercentral.com/articles/Configuring/managingmaxdegreeofparallelism/1029/).  Here is a quick synopsis of MAXDOP: It is a query hint you use when issuing a SQL statement that provides you control with how many processors SQL Server will use to execute the query. For complex queries with lots of I/O requirements, more CPUs can mean faster parallel searches. However the impact can be drastic on other running threads/processes. If your query takes all available processors at 100% for 5 minutes... guess what... nothing else works. The bottom line is that more is not always better. The use of MAXDOP is more art than science... and a whole lot of testing; it depends on two things: the underlying hardware architecture and the application design. So there isn't a magic number that will work for everyone... except 1... :) Let me explain. The rules of engagements are different. SQL Azure is about sharing. Yep... you are forced to nice with your neighbors.  To achieve this goal SQL Azure sets the MAXDOP to 1 by default, and ignores the use of the MAXDOP hint altogether. That means that all you queries will use one and only one processor.  It really isn't such a bad thing however. Keep in mind that in some of the largest SQL Server implementations MAXDOP is usually also set to 1. It is a well known configuration setting for large scale implementations. The reason is precisely to prevent rogue statements (like a SELECT * FROM HISTORY) from bringing down your systems (like a report that should have been running on a different in the first place) and to avoid the overhead generated by executing too many parallel queries that could cause internal memory management nightmares to the host Operating System. Is summary, forcing the MAXDOP to 1 in SQL Azure makes sense; it ensures that your database will continue to function normally even if one of the other tenants on the same server is running massive queries that would otherwise bring you down. Last but not least, keep in mind as well that when you test your database code for performance on-premise, make sure to set the DOP to 1 on your SQL Server databases to simulate SQL Azure conditions.

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• Is Python Interpreted or Compiled?

  - by crodjer

  This is just a wondering I had while reading about interpreted and compiled languages. Ruby is no doubt an interpreted language, since source code is compiled by an interpreter at the point of execution. On the contrary C is a compiled language, as one have to compile the source code first according to the machine and then execute. This results is much faster execution. Now coming to Python: A python code (somefile.py) when imported creates a file (somefile.pyc) in the same directory. Let us say the import is done in a python shell or django module. After the import I change the code a bit and execute the imported functions again to find that it is still running the old code. This suggests that *.pyc files are compiled python files similar to executable created after compilation of a C file, though I can't execute *.pyc file directly. When the python file (somefile.py) is executed directly ( ./somefile.py or python somefile.py ) no .pyc file is created and the code is executed as is indicating interpreted behavior. These suggest that a python code is compiled every time it is imported in a new process to crate a .pyc while it is interpreted when directly executed. So which type of language should I consider it as? Interpreted or Compiled? And how does its efficiency compare to interpreted and compiled languages? According to wiki's Interpreted Languages page it is listed as a language compiled to Virtual Machine Code, what is meant by that? Update Looking at the answers it seems that there cannot be a perfect answer to my questions. Languages are not only interpreted or only compiled, but there is a spectrum of possibilities between interpreting and compiling. From the answers by aufather, mipadi, Lenny222, ykombinator, comments and wiki I found out that in python's major implementations it is compiled to bytecode, which is a highly compressed and optimized representation and is machine code for a virtual machine, which is implemented not in hardware, but in the bytecode interpreter. Also the the languages are not interpreted or compiled, but rather language implementations either interpret or compile code. I also found out about Just in time compilation As far as execution speed is concerned the various benchmarks cannot be perfect and depend on context and the task which is being performed. Please tell if I am wrong in my interpretations.

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• Tim Heuer: A Guide to What Has Changed in Silverlight 4 RC

  Understand what has changed in the release candidate since the beta. The features still exist, but there are some changes to the implementations of some of the features, as well as some new ones....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Zend Framwork scaffolding capabilities

  - by rockstarz

  Are there any open source projects any of you would recommend to follow or contribute toward, including those already documented among the zf contributors, to add zend framework scaffolding of crud functionality for rapid development as found in many competitors frameworks (Yii, Symfony, Rails, Django, etc.)? As a user of zf on a daily basis on enterprise implementations, I know this is a topic of interest and I feel professional developers like you would find here would have something to contribute toward my question and finding a library that is underway that can be contributed to.

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• Building websites, which is the better approach MVP or MVC?

  - by Nick

  I'm looking for feedback on MVP and MVC patterns used as basis to build a website. I've used both with a certain degrees of success and failure. Furthermore I've worked in places which have miserable implement MVP across the web, desktop and services layers. I've also seen a few terrible MVC implementations. One thing I've noticed is the MVP stuff-up appear terrible for maintenance or adding any new features compared to the MVC debacles.

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• Is RTD Stateless or Stateful?

  - by [email protected]

  Yes.   A stateless service is one where each request is an independent transaction that can be processed by any of the servers in a cluster.  A stateful service is one where state is kept in a server's memory from transaction to transaction, thus necessitating the proper routing of requests to the right server. The main advantage of stateless systems is simplicity of design. The main advantage of stateful systems is performance. I'm often asked whether RTD is a stateless or stateful service, so I wanted to clarify this issue in depth so that RTD's architecture will be properly understood. The short answer is: "RTD can be configured as a stateless or stateful service." The performance difference between stateless and stateful systems can be very significant, and while in a call center implementation it may be reasonable to use a pure stateless configuration, a web implementation that produces thousands of requests per second is practically impossible with a stateless configuration. RTD's performance is orders of magnitude better than most competing systems. RTD was architected from the ground up to achieve this performance. Features like automatic and dynamic compression of prediction models, automatic translation of metadata to machine code, lack of interpreted languages, and separation of model building from decisioning contribute to achieving this performance level. Because  of this focus on performance we decided to have RTD's default configuration work in a stateful manner. By being stateful RTD requests are typically handled in a few milliseconds when repeated requests come to the same session. Now, those readers that have participated in implementations of RTD know that RTD's architecture is also focused on reducing Total Cost of Ownership (TCO) with features like automatic model building, automatic time windows, automatic maintenance of database tables, automatic evaluation of data mining models, automatic management of models partitioned by channel, geography, etcetera, and hot swapping of configurations. How do you reconcile the need for a low TCO and the need for performance? How do you get the performance of a stateful system with the simplicity of a stateless system? The answer is that you make the system behave like a stateless system to the exterior, but you let it automatically take advantage of situations where being stateful is better. For example, one of the advantages of stateless systems is that you can route a message to any server in a cluster, without worrying about sending it to the same server that was handling the session in previous messages. With an RTD stateful configuration you can still route the message to any server in the cluster, so from the point of view of the configuration of other systems, it is the same as a stateless service. The difference though comes in performance, because if the message arrives to the right server, RTD can serve it without any external access to the session's state, thus tremendously reducing processing time. In typical implementations it is not rare to have high percentages of messages routed directly to the right server, while those that are not, are easily handled by forwarding the messages to the right server. This architecture usually provides the best of both worlds with performance and simplicity of configuration.   Configuring RTD as a pure stateless service A pure stateless configuration requires session data to be persisted at the end of handling each and every message and reloading that data at the beginning of handling any new message. This is of course, the root of the inefficiency of these configurations. This is also the reason why many "stateless" implementations actually do keep state to take advantage of a request coming back to the same server. Nevertheless, if the implementation requires a pure stateless decision service, this is easy to configure in RTD. The way to do it is: Mark every Integration Point to Close the session at the end of processing the message In the Session entity persist the session data on closing the session In the session entity check if a persisted version exists and load it An excellent solution for persisting the session data is Oracle Coherence, which provides a high performance, distributed cache that minimizes the performance impact of persisting and reloading the session. Alternatively, the session can be persisted to a local database. An interesting feature of the RTD stateless configuration is that it can cope with serializing concurrent requests for the same session. For example, if a web page produces two requests to the decision service, these requests could come concurrently to the decision services and be handled by different servers. Most stateless implementation would have the two requests step onto each other when saving the state, or fail one of the messages. When properly configured, RTD will make one message wait for the other before processing.   A Word on Context Using the context of a customer interaction typically significantly increases lift. For example, offer success in a call center could double if the context of the call is taken into account. For this reason, it is important to utilize the contextual information in decision making. To make the contextual information available throughout a session it needs to be persisted. When there is a well defined owner for the information then there is no problem because in case of a session restart, the information can be easily retrieved. If there is no official owner of the information, then RTD can be configured to persist this information.   Once again, RTD provides flexibility to ensure high performance when it is adequate to allow for some loss of state in the rare cases of server failure. For example, in a heavy use web site that serves 1000 pages per second the navigation history may be stored in the in memory session. In such sites it is typical that there is no OLTP that stores all the navigation events, therefore if an RTD server were to fail, it would be possible for the navigation to that point to be lost (note that a new session would be immediately established in one of the other servers). In most cases the loss of this navigation information would be acceptable as it would happen rarely. If it is desired to save this information, RTD would persist it every time the visitor navigates to a new page. Note that this practice is preferred whether RTD is configured in a stateless or stateful manner.  

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• Oracle redonne un élan au Projet Lambda sur Java 7 et les closures : Interface evolution via "public

  Bonjour, Depuis quelques temps, on n'entendait plus trop parler des Closures et de leur ajout à Java 7. En réponse à David Flanagan qui s'inquiétait récemment du silence d'Oracle et de la stagnation du Project Lambda, Brian Goetz (Oracle) a soumis il y a quelques jours un document de réflexion sur la notion de virtual extension methods permettant d'ajouter sur une interface existante de nouvelles méthodes (avec des implémentations par défaut) sans casser le contrat avec le code existant.

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• Looking for a C# implementation of (Pk) Zip32

  - by bukko

  I need to implement Zip32 (PK compatible) in C#. I can't just call a separate dll or exe because (1) I don't want to write the uncompressed file to disk and (2) I want to avoid the possibly that someone could wrap that library - either of these would compromise security. My ideal solution would be to find a C# implementation of the Zip32 algorithm which I could use, and just modify it so I can pass a byte array or something. Does anyone have any suggestions or (I dare but hope) examples of C# PKZip implementations?

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• Download NServiceBus Framework

  - by Editor

  NServiceBus is a highly extensible, publish/subscribe, workflow integrated communications framework for .NET. NServiceBus is a lightweight higher-level API built on top of MSMQ and based on one-way messaging. For now the Technological Implementation is based on MSMQ, though other implementations are considered. Download NServiceBus.

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