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• Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

  - by MarkPearl

  After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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• Thread.Interrupt Is Evil

  - by Alois Kraus

  Recently I have found an interesting issue with Thread.Interrupt during application shutdown. Some application was crashing once a week and we had not really a clue what was the issue. Since it happened not very often it was left as is until we have got some memory dumps during the crash. A memory dump usually means WindDbg which I really like to use (I know I am one of the very few fans of it).  After a quick analysis I did find that the main thread already had exited and the thread with the crash was stuck in a Monitor.Wait. Strange Indeed. Running the application a few thousand times under the debugger would potentially not have shown me what the reason was so I decided to what I call constructive debugging. I did create a simple Console application project and try to simulate the exact circumstances when the crash did happen from the information I have via memory dump and source code reading. The thread that was  crashing was actually MS code from an old version of the Microsoft Caching Application Block. From reading the code I could conclude that the main thread did call the Dispose method on the CacheManger class which did call Thread.Interrupt on the cache scavenger thread which was just waiting for work to do. My first version of the repro looked like this   static void Main(string[] args) { Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); } static void ThreadFunc() { while (true) { object value = Dequeue(); // block until unblocked or awaken via ThreadInterruptedException } } static object WaitObject = new object(); static object Dequeue() { object lret = "got value"; try { lock (WaitObject) { } } catch (ThreadInterruptedException) { Console.WriteLine("Got ThreadInterruptException"); lret = null; } return lret; } I do start a background thread and call Thread.Interrupt on it and then directly let the application terminate. The thread in the meantime does plenty of Monitor.Enter/Leave calls to simulate work on it. This first version did not crash. So I need to dig deeper. From the memory dump I did know that the finalizer thread was doing just some critical finalizers which were closing file handles. Ok lets add some long running finalizers to the sample. class FinalizableObject : CriticalFinalizerObject { ~FinalizableObject() { Console.WriteLine("Hi we are waiting to finalize now and block the finalizer thread for 5s."); Thread.Sleep(5000); } } class Program { static void Main(string[] args) { FinalizableObject fin = new FinalizableObject(); Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); GC.KeepAlive(fin); // prevent finalizing it too early // After leaving main the other thread is woken up via Thread.Abort // while we are finalizing. This causes a stackoverflow in the CLR ThreadAbortException handling at this time. } With this changed Main method and a blocking critical finalizer I did get my crash just like the real application. The funny thing is that this is actually a CLR bug. When the main method is left the CLR does suspend all threads except the finalizer thread and declares all objects as garbage. After the normal finalizers were called the critical finalizers are executed to e.g. free OS handles (usually). Remember that I did call Thread.Interrupt as one of the last methods in the Main method. The Interrupt method is actually asynchronous and does wake a thread up and throws a ThreadInterruptedException only once unlike Thread.Abort which does rethrow the exception when an exception handling clause is left. It seems that the CLR does not expect that a frozen thread does wake up again while the critical finalizers are executed. While trying to raise a ThreadInterrupedException the CLR goes down with an stack overflow. Ups not so nice. Why has this nobody noticed for years is my next question. As it turned out this error does only happen on the CLR for .NET 4.0 (x86 and x64). It does not show up in earlier or later versions of the CLR. I have reported this issue on connect here but so far it was not confirmed as a CLR bug. But I would be surprised if my console application was to blame for a stack overflow in my test thread in a Monitor.Wait call. What is the moral of this story? Thread.Abort is evil but Thread.Interrupt is too. It is so evil that even the CLR of .NET 4.0 contains a race condition during the CLR shutdown. When the CLR gurus can get it wrong the chances are high that you get it wrong too when you use this constructs. If you do not believe me see what Patrick Smacchia does blog about Thread.Abort and List.Sort. Not only the CLR creators can get it wrong. The BCL writers do sometimes have a hard time with correct exception handling as well. If you do tell me that you use Thread.Abort frequently and never had problems with it I do suspect that you do not have looked deep enough into your application to find such sporadic errors.

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• Oracle Enterprise Manager Cloud Control 12c Release 2 (12.1.0.2) is Available Now !

  - by Anand Akela

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} Oracle today announced the availability of Oracle Enterprise Manager Cloud Control 12c Release 2 (12.1.0.2). It is now available for download on OTN on ALL platforms. This is the first major release since the launch of Enterprise Manager 12c in October of 2011. This is the first time when Enterprise Manager release is available on all platforms simultaneously. This is primarily a stability release which incorporates many of issues and feedback reported by early adopters. In addition, this release contains many new features and enhancements in areas across the board. New Capabilities and Features Enhanced management capabilities for enterprise private clouds: Introduces new capabilities to allow customers to build and manage a Java Platform-as-a-Service (PaaS) cloud based on Oracle Weblogic Server. The new capabilities include guided set up of PaaS Cloud, self-service provisioning, automatic scale out and metering and chargeback. Enhanced lifecycle management capabilities for Oracle WebLogic Server environments: Combining in-context multiple domain, patching and configuration file synchronizations. Integrated Hardware-Software management for Oracle Exalogic Elastic Cloud through features such as rack schematics visualization and integrated monitoring of all hardware and software components. The latest management capabilities for business-critical applications include: Business Application Management: A new Business Application (BA) target type and dashboard with flexible definitions provides a logical view of an application’s business transactions, end-user experiences and the cloud infrastructure the monitored application is running on. Enhanced User Experience Reporting: Oracle Real User Experience Insight has been enhanced to provide reporting capabilities on client-side issues for applications running in the cloud and has been more tightly coupled with Oracle Business Transaction Management to help ensure that real-time user experience and transaction tracing data is provided to users in context. Several key improvements address ease of administration, reporting and extensibility for massively scalable cloud environments including dynamic groups, self-updateable monitoring templates, bulk operations against many events, etc. New and Revised Plug-Ins: Several plug-Ins have been updated as a part of this release resulting in either new versions or revisions. Revised plug-ins contain only bug-fixes and while new plug-ins incorporate both bug fixes as well as new functionality. Plug-In Name Version Enterprise Manager for Oracle Database 12.1.0.2 (revision) Enterprise Manager for Oracle Fusion Middleware 12.1.0.3 (new) Enterprise Manager for Chargeback and Capacity Planning 12.1.0.3 (new) Enterprise Manager for Oracle Fusion Applications 12.1.0.3 (new) Enterprise Manager for Oracle Virtualization 12.1.0.3 (new) Enterprise Manager for Oracle Exadata 12.1.0.3 (new) Enterprise Manager for Oracle Cloud 12.1.0.4 (new) Installation and Upgrade: All major platforms have been released simultaneously (Linux 32 / 64 bit, Solaris (SPARC), Solaris x86-64, IBM AIX 64-bit, and Windows x86-64 (64-bit) ) Enterprise Manager 12.1.0.2 is a complete release that includes both the EM OMS and Agent versions of 12.1.0.2. Installation options available with EM 12.1.0.2: User can do fresh Install or an upgrade from versions EM 10.2.0.5, 11.1, or 12.1.0.2 ( Bundle Patch 1 not mandatory). Upgrading to EM 12.1.0.2 from EM 12.1.0.1 is not a patch application (similar to Bundle Patch 1) but is achieved through a 1-system upgrade. Documentation: Oracle Enterprise Manager Cloud Control Introduction Document provides a broad overview of capabilities and highlights"What's New" in EM 12.1.0.2. All updated Oracle Enterprise Manager documentation can be found on OTN Upgrade Guide Please feel free to ask questions related to the new Oracle Enterprise Manager Cloud Control 12c Release 2 (12.1.0.2) at the Oracle Enterprise Manager Forum . You could also share your feedback at twitter  using hash tag #em12c or at Facebook . Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Newsletter

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• Webcor Builders Coordinates Construction Schedules and Mitigates Potential Delays More Efficiently with Integrated Project Management

  - by Sylvie MacKenzie, PMP

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} With more than 40 years of commercial construction experience, Webcor Builders is a leading builder of distinguished, high-profile projects, including high-rise condominiums and hotels, laboratories, healthcare centers, and public works projects. Webcor is also known for its award-winning concrete, interior construction, historic restoration, and seismic renovation work. The company has completed more than 50 million square feet of projects to date. Considering the variety and complexity of the construction projects Webcor undertakes, an integrated project management solution is critical to ensuring optimal efficiency and completing client projects on time and on budget. The company previously used a number of scheduling systems for its various building projects. These packages provided different levels of schedule detail and required schedulers, engineers, and other employees to learn multiple systems. From an IT cost and complexity perspective, the company had to manage multiple scheduling systems and pay for multiple sets of licenses. The company looked to standardize on an enterprise project management system, and selected Oracle’s Primavera P6 Enterprise Project Portfolio Management. Webcor uses the solution’s advanced capabilities to schedule complex projects, analyze delays, model and propose multiple scenarios to demonstrate and mitigate delays and cost overruns, and process that information efficiently to deliver the scheduling precision that public and private projects require. In fact, the solution was instrumental in helping the company’s expansion into public sector projects during the recent economic downturn, and with Primavera P6 in place, it can deliver the precise schedule reporting required for large public projects. With Primavera P6 in place, the company could deliver the precise scheduling and milestone reporting capabilities required for large public projects. The solution is in managing the high-profile University of California – Berkeley Memorial Stadium project. Webcor was hired as construction manager and general contractor for the stadium renovation project, which is a fast-paced project located near the seismically active Hayward Fault Zone. Due to the University of California’s football schedule, meeting the Universities deadline for the coming season placed Webcor in a situation where risk awareness and early warnings of issues would be paramount. Webcor and the extended project team needed a solution that could instantly analyze alternate scenarios to mitigate potential delays; Primavera would deliver those answers.The team would also need to enable multiple stakeholders to use an internet-based platform to access the schedule from various locations, and model complicated sequencing requirements where swift decisions would be made to keep the project on track. The schedule is an integral part of Webcor’s construction management process for the stadium project. Rather than providing the client with the industry-standard monthly update, Webcor updates the critical path method (CPM) schedule on a weekly basis. The project team also reviews the schedule and updates weekly to confirm that progress and forecasted performance are accurate. Hired by the University for their ability to deliver in high risk environments The Webcor team was hit recently with a design supplement that could have added up to 70 days to the project. Using Oracle Primavera P6 the team sprung into action analyzing multiple “what if” scenarios to review mitigation means and methods.  Determined to make sure the Bears could take the field in the coming season the project team nearly eliminated the impact with their creative analysis in working the schedule. The total time from the issuance of the final design supplement to an agreed mitigation response was less than one week; leveraging the Oracle Primavera solution Webcor was able to deliver superior customer value With the ability to efficiently manage projects and schedules, Webcor can ensure it completes its projects on time and on budget, as well as inform clients about what changes to plans will mean in terms of delays and additional costs. Read the complete customer case study at :  http://www.oracle.com/us/corporate/customers/customersearch/webcor-builders-1-primavera-ss-1639886.html

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• Impressions and Reactions from Alliance 2012

  - by user739873

  Alliance 2012 has come to a conclusion.  What strikes me about every Alliance conference is the amazing amount of collaboration and cooperation I see across higher education in the sharing of best practices around the entire Oracle PeopleSoft software suite, not just the student information system (Oracle’s PeopleSoft Campus Solutions).  In addition to the vibrant U.S. organization, it's gratifying to see the growth in the international attendance again this year, with an EMEA HEUG organizing to complement the existing groups in the Netherlands, South Africa, and the U.K.  Their first meeting is planned for London in October, and I suspect they'll be surprised at the amount of interest and attendance. In my discussions with higher education IT and functional leadership at Alliance there were a number of instances where concern was expressed about Oracle's commitment to higher education as an industry, primarily because of a lack of perceived innovation in the applications that Oracle develops for this market. Here I think perception and reality are far apart, and I'd like to explain why I believe this to be true. First let me start with what I think drives this perception. Predominately it's in two areas. The first area is the user interface, both for students and faculty that interact with the system as "customers", and for those employees of the institution (faculty, staff, and sometimes students as well) that use the system in some kind of administrative role. Because the UI hasn't changed all that much from the PeopleSoft days, individuals perceive this as a dead product with little innovation and therefore Oracle isn't investing. The second area is around the integration of the higher education suite of applications (PeopleSoft Campus Solutions) and the rest of the Oracle software assets. Whether grown organically or acquired, there is an impressive array of middleware and other software products that could be leveraged much more significantly by the higher education applications than is currently the case today. This is also perceived as lack of investment. Let me address these two points.  First the UI.  More is being done here than ever before, and the PAG and other groups where this was discussed at Alliance 2012 were more numerous than I've seen in any past meeting. Whether it's Oracle development leveraging web services or some extremely early but very promising work leveraging the recent Endeca acquisition (see some cool examples here) there are a lot of resources aimed at this issue.  There are also some amazing prototypes being developed by our UX (user experience team) that will eventually make their way into the higher education applications realm - they had an impressive setup at Alliance.  Hopefully many of you that attended found this group. If not, the senior leader for that team Jeremy Ashley will be a significant contributor of content to our summer Industry Strategy Council meeting in Washington in June. In the area of integration with other elements of the Oracle stack, this is also an area of focus for the company and my team.  We're making this a priority especially in the areas of identity management and security, leveraging WebCenter more effectively for content, imaging, and mobility, and driving towards the ultimate objective of WebLogic Suite as our platform for SOA, links to learning management systems (SAIP), and content. There is also much work around business intelligence centering on OBI applications. But at the end of the day we get enormous value from the HEUG (higher education user group) and the various subgroups formed as a part of this community that help us align and prioritize our investments, whether it's around better integration with other Oracle products or integration with partner offerings.  It's one of the healthiest, mutually beneficial relationships between customers and an Education IT concern that exists on the globe. And I can't avoid mentioning that this kind of relationship between higher education and the corporate IT community that can truly address the problems of efficiency and effectiveness, institutional excellence (which starts with IT) and student success.  It's not (in my opinion) going to be solved through community source - cost and complexity only increase in that model and in the end higher education doesn't ultimately focus on core competencies: educating, developing, and researching.  While I agree with some of what Michael A. McRobbie wrote in his EDUCAUSE Review article (Information Technology: A View from Both Sides of the President’s Desk), I take strong issue with his assertion that the "the IT marketplace is just the opposite of long-term stability...."  Sure there has been healthy, creative destruction in the past 2-3 decades, but this has had the effect of, in the aggregate, benefiting education with greater efficiency, more innovation and increased stability as larger, more financially secure firms acquire and develop integrated solutions. Cole

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• Take Two: Comparing JVMs on ARM/Linux

  - by user12608080

  Although the intent of the previous article, entitled Comparing JVMs on ARM/Linux, was to introduce and highlight the availability of the HotSpot server compiler (referred to as c2) for Java SE-Embedded ARM v7,  it seems, based on feedback, that everyone was more interested in the OpenJDK comparisons to Java SE-E.  In fact there were two main concerns: The fact that the previous article compared Java SE-E 7 against OpenJDK 6 might be construed as an unlevel playing field because version 7 is newer and therefore potentially more optimized. That the generic compiler settings chosen to build the OpenJDK implementations did not put those versions in a particularly favorable light. With those considerations in mind, we'll institute the following changes to this version of the benchmarking: In order to help alleviate an additional concern that there is some sort of benchmark bias, we'll use a different suite, called DaCapo.  Funded and supported by many prestigious organizations, DaCapo's aim is to benchmark real world applications.  Further information about DaCapo can be found at http://dacapobench.org. At the suggestion of Xerxes Ranby, who has been a great help through this entire exercise, a newer Linux distribution will be used to assure that the OpenJDK implementations were built with more optimal compiler settings.  The Linux distribution in this instance is Ubuntu 11.10 Oneiric Ocelot. Having experienced difficulties getting Ubuntu 11.10 to run on the original D2Plug ARMv7 platform, for these benchmarks, we'll switch to an embedded system that has a supported Ubuntu 11.10 release.  That platform is the Freescale i.MX53 Quick Start Board.  It has an ARMv7 Coretex-A8 processor running at 1GHz with 1GB RAM. We'll limit comparisons to 4 JVM implementations: Java SE-E 7 Update 2 c1 compiler (default) Java SE-E 6 Update 30 (c1 compiler is the only option) OpenJDK 6 IcedTea6 1.11pre 6b23~pre11-0ubuntu1.11.10.2 CACAO build 1.1.0pre2 OpenJDK 6 IcedTea6 1.11pre 6b23~pre11-0ubuntu1.11.10.2 JamVM build-1.6.0-devel Certain OpenJDK implementations were eliminated from this round of testing for the simple reason that their performance was not competitive.  The Java SE 7u2 c2 compiler was also removed because although quite respectable, it did not perform as well as the c1 compilers.  Recall that c2 works optimally in long-lived situations.  Many of these benchmarks completed in a relatively short period of time.  To get a feel for where c2 shines, take a look at the first chart in this blog. The first chart that follows includes performance of all benchmark runs on all platforms.  Later on we'll look more at individual tests.  In all runs, smaller means faster.  The DaCapo aficionado may notice that only 10 of the 14 DaCapo tests for this version were executed.  The reason for this is that these 10 tests represent the only ones successfully completed by all 4 JVMs.  Only the Java SE-E 6u30 could successfully run all of the tests.  Both OpenJDK instances not only failed to complete certain tests, but also experienced VM aborts too. One of the first observations that can be made between Java SE-E 6 and 7 is that, for all intents and purposes, they are on par with regards to performance.  While it is a fact that successive Java SE releases add additional optimizations, it is also true that Java SE 7 introduces additional complexity to the Java platform thus balancing out any potential performance gains at this point.  We are still early into Java SE 7.  We would expect further performance enhancements for Java SE-E 7 in future updates. In comparing Java SE-E to OpenJDK performance, among both OpenJDK VMs, Cacao results are respectable in 4 of the 10 tests.  The charts that follow show the individual results of those four tests.  Both Java SE-E versions do win every test and outperform Cacao in the range of 9% to 55%. For the remaining 6 tests, Java SE-E significantly outperforms Cacao in the range of 114% to 311% So it looks like OpenJDK results are mixed for this round of benchmarks.  In some cases, performance looks to have improved.  But in a majority of instances, OpenJDK still lags behind Java SE-Embedded considerably. Time to put on my asbestos suit.  Let the flames begin...

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• Private Cloud: Putting some method behind the madness

  - by Sudip Datta

  Finally, I decided to join the blogging community. And what could be a better time to start than the week after OpenWorld 2012. 50K+ attendees, demonstrations, speaker sessions and a whole lot of buzz on Oracle Cloud..It was raining clouds in this year's Openworld. I am not here to write about Oracle's cloud strategy in general, but on Enterprise Manager's cloud management capabilities. This year's Openworld was the first after we announced the 12c Cloud Control and we were happy to share the stage with quite a few early adopters. Stay tuned for videos from our customers and partners, I will post them as they get published. I met a number of platform administrators in Oracle-DBAs, Middleware Admins, SOA Admins...The cloud has affected them all, at least to the point where it beckoned more than just curiosity..Most IT infrastructure are already heavily virtualized (on VMWare and on others including Oracle VM), and some would claim they are already on “cloud” (at least their Sysadmins told them so). But none of them were confident of the benefits because their pain points continued to grow.. Isn't cloud supposed to ease those? Instead, they were chasing hundreds of databases running on hundreds of VMs, often with as much certainty propounded by Heisenberg. What happened to the age-old IT discipline around administration, compliance, configuration management? VMs are great for what they are. I personally think they have opened the doors to new approaches in which an application stack gets provisioned and updated. In fact, Enterprise Manager 12c is possibly the only tool out there that can provision full-fledged application as VM Assemblies. In this year's Openworld, customers talked on how they provisioned RAC and Siebel assemblies, which as the techies out there know, are not trivial (hearing provisioning time for Siebel down from weeks to hours was gratifying indeed). However, I do have an issue with a "one-size fits all" approach to cloud. In a week's span, I met several personas: Project owners requiring an EC2 like VM instance for their projects Admins needing the same for Sparc-Solaris. DBAs requiring dedicated databases for new projects APEX Developers needing just a ready-to-consume schema as a service Java Developers looking for a runtime platform QA engineers needing a fast clone of their production environment If you drill down further, you will end up peeling more layers of the details. For example, the requirements for Load testing and Functional testing are very different. For Load testing the test environment should ideally be the same as the production. You shouldn't run production on Exadata and load test on a VM; they will just not be good representations of one another. For Functional testing it does not possibly matter. DBAs seem to be at the worst affected of the lot. It seems they have been asked to choose between agile provisioning and  faster runtime performance. And in some cases, it is really a Hobson's choice, because their infrastructure provider made no distinction between the OLTP application and the Virtual desktop! Sad indeed. When one looks at the portfolio of services that we already offer (vanilla IaaS, VM Assembly based PaaS, DBaaS) or have announced (Java PaaS, Instant Cloning, Schema-aaS), one can possibly think that we are trying to be the "renaissance man" ! Well I would have possibly digested that had it not been for the various personas that I described above. Getting the use cases right is very important for an application such as cloud management. We iterate and iterate over these over and over again and re-validate them in CABs (Customer Advisory Boards). We consider over the major aspects of tenancy: service placement, resource isolation (can a tenant execute an expensive SQL and run away with all the resources), quota and security. We, in Engineering, keep reminding ourselves that we are dealing with enterprise clouds. We owe it to our customer base ! In the coming posts, I will drill down more into each of the services. In the meanwhile, here are some collateral and  demos for starters with EM 12c. http://www.oracle.com/technetwork/oem/cloud-mgmt/index.html Sudip Datta The views expressed here are my own and do not necessarily reflect the views of Oracle. Stay Connected: Twitter | Facebook | YouTube | Linkedin | Newsletter --

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• Windows Phone 8 Announcement

  - by Tim Murphy

  As if the Surface announcement on Monday wasn’t exciting enough, today Microsoft announce that Windows Phone 8 will be coming this fall.  That itself is great news, but the features coming were like confetti flying in all different directions.  Given this speed I couldn’t capture every feature they covered.  A summary of what I did capture is listed below starting with their eight main features. Common Core The first thing that they covered is that Windows Phone 8 will share a core OS with Windows 8.  It will also run natively on multiple cores.  They mentioned that they have run it on up to 64 cores to this point.  The phones as you might expect will at least start as dual core.  If you remember there were metrics saying that Windows Phone 7 performed operations faster on a single core than other platforms did with dual cores.  The metrics they showed here indicate that Windows Phone 8 runs faster on comparable dual core hardware than other platforms. New Screen Resolutions Screen resolution has never been an issue for me, but it has been a criticism of Windows Phone 7 in the media.  Windows Phone 8 will supports three screen resolutions: WVGA 800 x 480, WXGA 1280 x 768, and 720 1280x720.  Hopefully this makes pixel counters a little happier. MicroSD Support This was one of my pet peeves when I got my Samsung Focus. With Windows Phone 8 the operating system will support adding MicroSD cards after initial setup.  Of course this is dependent on the hardware company on implementing it, but I think we have seen that even feature phone manufacturers have not had a problem supporting this in the past. NFC NFC has been an anticipated feature for some time.  What Microsoft showed today included the fact that they didn’t just want it to be for the phone.  There is cross platform NFC functionality between Windows Phone 8 and Windows 8.  The demos , while possibly a bit fanciful, showed would could be achieved even in a retail environment.  We are getting closer and closer to a Minority Report world with these technologies. Wallet Windows Phone 8 isn’t the first platform to have a wallet concept.  What they have done to differentiate themselves is to make it sot that it is not dependent on a SIM type chip like other platforms.  They have also expanded the concept beyond just banks to other types of credits such as airline miles. Nokia Mapping People have been envious of the Lumia phones having the Nokia mapping software.  Now all Windows Phone 8 devices will use NavTeq data and will have the capability to run in an offline fashion.  This is a major step forward from the Bing “touch for the next turn” maps. IT Administration The lack of features for enterprise administration and deployment was a complaint even before the Windows Phone 7 was released.  With the Windows Phone 8 release such features as Bitlocker and Secure boot will be baked into the OS. We will also have the ability to privately sign and distribute applications. Changing Start Screen Joe Belfiore made a big deal about this aspect of the new release.  Users will have more color themes available to them and the live tiles will be highly customizable. You will have the ability to resize and organize the tiles in a more dynamic way.  This allows for less important tiles or ones with less information to be made smaller.  And There Is More So what other tidbits came out of the presentation?  Later this summer the API for WP8 will be available.  There will be developer events coming to a city near you.  Another announcement of interest to developers is the ability to write applications at a native code level.  This is a boon for game developers and those who need highly efficient applications. As a topper on the cake there was mention of in app payment. On the consumer side we also found out that all updates will be available over the air.  Along with this came the fact that Microsoft will support all devices with updates for at least 18 month and you will be able to subscribe for early updates.  Update coming for Windows Phone 7.5 customers to WP7.8.  The main enhancement will be the new live tile features.  The big bonus is that the update will bypass the carriers.  I would assume though that you will be brought up to date with all previous patches that your carrier may not have released. There is so much more, but that is enough for one post.  Needless to say, EXCITING! del.icio.us Tags: Windows Phone 8,WP8,Windows Phone 7,WP7,Announcements,Microsoft

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• The Best BPM Journey: More Exciting Destinations with Process Accelerators

  - by Cesare Rotundo

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Oracle Open World (OOW) earlier this month has been a great occasion to discuss with our BPM customers. It was interesting to hear definite patterns emerging from those conversations: “BPM is a journey”, “experiences to share”, “our organization now understands what BPM is”, and my favorite (with some caveats): “BPM is like wine tasting, once you start, you want to try more”. These customers have started their journey, climbed up the learning curve, and reached a vantage point that allows them to see their next BPM destination. They see the next few processes they are going to tackle and improve with BPM. These processes/destinations target both horizontal processes where BPM replaces or coordinates manual activities, and critical industry processes that the company needs to improve to compete and deliver increasing value. Each new destination generates value, allowing the organization to reduce the cost of manual processes that were not supported by apps/custom development, and increase efficiency of end-to-end processes partially covered by apps/custom dev. The question we wanted to answer is how to help organizations experience deeper success with BPM, by increasing their awareness of the potential for reaching new targets, and equipping them with the right tools. We decided that we needed to identify destinations, and plot routes to show the fastest path to those destinations. In the end we want to enable customers to reach “Process Excellence”: continuously set new targets and consistently and efficiently reach them. The result is Oracle Process Accelerators (PA), solutions built using the rich functionality in Oracle BPM Suite. PAs offers a rapidly expanding list of exciting destinations. Our launch of the latest installment of Process Accelerators at Oracle Open World includes new Industry-focused solutions such as Public Sector Incident Reporting and Financial Services Loan Origination, and improved other horizontal PAs, including Travel Request Management, Document Routing and Approval, and Internal Service Requests. Just before OOW we had extended the Oracle deployment of Travel Request Management, riding the enthusiastic response from early adopters among travelers (employees), management and support (approvers). “Getting there first” means being among the first to extract value from the PA approach, while acquiring deeper insights into the customers’ perspective. This is especially noteworthy when it comes to PAs, a set of solutions designed to be quickly deployed and iteratively improved by customers. The OOW launch has generated immediate feedback from customers, non-customers, analysts, and partners. They all confirmed that both Business and IT at organizations benefit from PAs when it comes to exploring the potential for BPM to improve their business processes. PAs help customers visualize what can be done with BPM, and PAs are made to be extended: you can see your destination, change the path to fit your needs, and deploy. We're discovering new destinations/processes that the market wants us to support, generic enough across industries and within industries. We'll keep on building sets of requirements, deliver functional design, construct solutions using Oracle BPM, and test them not only functionally but for performance, scalability, clustering, making them robust, product-quality. Delivering BPM solutions with product-grade quality is the equivalent of following a tried-and-tested path on a map. Do you know of existing destinations in your industry? If yes, we can draw a path to innovative processes together.

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• Clouds, Clouds, Clouds Everywhere, Not a Drop of Rain!

  - by sxkumar

  At the recently concluded Oracle OpenWorld 2012, the center of discussion was clearly Cloud. Over the five action packed days, I got to meet a large number of customers and most of them had serious interest in all things cloud.  Public Cloud - particularly the Oracle Cloud - clearly got a lot of attention and interest. I think the use cases and the value proposition for public cloud is pretty straight forward. However, when it comes to private cloud, there were some interesting revelations.  Well, I shouldn’t really call them revelations since they are pretty consistent with what I have heard from customers at other conferences as well as during 1:1 interactions. While the interest in enterprise private cloud remains to be very high, only a handful of enterprises have truly embarked on a journey to create what the purists would call true private cloud - with capabilities such as self-service and chargeback/show back. For a large majority, today's reality is simply consolidation and virtualization - and they are quite far off from creating an agile, self-service and transparent IT infrastructure which is what the enterprise cloud is all about.  Even a handful of those who have actually implemented a close-to-real enterprise private cloud have taken an infrastructure centric approach and are seeing only limited business upside. Quite a few were frank enough to admit that chargeback and self-service isn’t something that they see an immediate need for.  This is in quite contrast to the picture being painted by all those surveys out there that show a large number of enterprises having already implemented an enterprise private cloud.  On the face of it, this seems quite contrary to the observations outlined above. So what exactly is the reality? Well, the reality is that there is undoubtedly a huge amount of interest among enterprises about transforming their legacy IT environment - which is often seen as too rigid, too fragmented, and ultimately too expensive - to something more agile, transparent and business-focused. At the same time however, there is a great deal of confusion among CIOs and architects about how to get there. This isn't very surprising given all the buzz and hype surrounding cloud computing. Every IT vendor claims to have the most unique solution and there isn't a single IT product out there that does not have a cloud angle to it. Add to this the chatter on the blogosphere, it will get even a sane mind spinning.  Consequently, most  enterprises are still struggling to fully understand the concept and value of enterprise private cloud.  Even among those who have chosen to move forward relatively early, quite a few have made their decisions more based on vendor influence/preferences rather than what their businesses actually need.  Clearly, there is a disconnect between the promise of the enterprise private cloud and the current adoption trends.  So what is the way forward?  I certainly do not claim to have all the answers. But here is a perspective that many cloud practitioners have found useful and thus worth sharing. To take a step back, the fundamental premise of the enterprise private cloud is IT transformation. It is the quest to create a more agile, transparent and efficient IT infrastructure that is driven more by business needs rather than constrained by operational and procedural inefficiencies. It is the new way of delivering and consuming IT services - where the IT organizations operate more like enablers of  strategic services rather than just being the gatekeepers of IT resources. In an enterprise private cloud environment, IT organizations are expected to empower the end users via self-service access/control and provide the business stakeholders a transparent view of how the resources are being used, what’s the cost of delivering a given service, how well are the customers being served, etc.  But the most important thing to note here is the enterprise private cloud is not just an IT project, rather it is a business initiative to create an IT setup that is more aligned with the needs of today's dynamic and highly competitive business environment. Surprised? You shouldn’t be. Just remember how the business users have been at the forefront of public cloud adoption within enterprises and private cloud is no exception.   Such a broad-based transformation makes cloud more than a technology initiative. It requires people (organizational) and process changes as well, and these changes are as critical as is the choice of right tools and technology. In my next blog,  I will share how essential it is for enterprise cloud technology to go hand-in hand with process re-engineering and organization changes to unlock true value of  enterprise cloud. I am sharing a short video from my session "Managing your private Cloud" at Oracle OpenWorld 2012. More videos from this session will be posted at the recently introduced Zero to Cloud resource page. Many other experts of Oracle enterprise private cloud solution will join me on this blog "Zero to Cloud"  and share best practices , deployment tips and information on how to plan, build, deploy, monitor, manage , meter and optimize the enterprise private cloud. We look forward to your feedback, suggestions and having an engaging conversion with you on this blog.

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• No More NCrunch For Me

  - by Steve Wilkes

  When I opened up Visual Studio this morning, I was greeted with this little popup: NCrunch is a Visual Studio add-in which runs your tests while you work so you know if and when you've broken anything, as well as providing coverage indicators in the IDE and coverage metrics on demand. It recently went commercial (which I thought was fair enough), and time is running out for the free version I've been using for the last couple of months. From my experiences using NCrunch I'm going to let it expire, and go about my business without it. Here's why. Before I start, let me say that I think NCrunch is a good product, which is to say it's had a positive impact on my programming. I've used it to help test-drive a library I'm making right from the start of the project, and especially at the beginning it was very useful to have it run all my tests whenever I made a change. The first problem is that while that was cool to start with, it’s recently become a bit of a chore. Problems Running Tests NCrunch has two 'engine modes' in which it can run tests for you - it can run all your tests when you make a change, or it can figure out which tests were impacted and only run those. Unfortunately, it became clear pretty early on that that second option (which is marked as 'experimental') wasn't really working for me, so I had to have it run everything. With a smallish number of tests and while I was adding new features that was great, but I've now got 445 tests (still not exactly loads) and am more in a 'clean and tidy' mode where I know that a change I'm making will probably only affect a particular subset of the tests. With that in mind it's a bit of a drag sitting there after I make a change and having to wait for NCrunch to run everything. I could disable it and manually run the tests I know are impacted, but then what's the point of having NCrunch? If the 'impacted only' engine mode worked well this problem would go away, but that's not what I found. Secondly, what's wrong with this picture? I've got 445 tests, and NCrunch has queued 455 tests to run. So it's queued duplicate tests - in this quickly-screenshotted case 10, but I've seen the total queue get up over 600. If I'm already itchy waiting for it to run all my tests against a change I know only affects a few, I'm even itchier waiting for it to run a lot of them twice. Problems With Code Coverage NCrunch marks each line of code with a dot to say if it's covered by tests - a black dot says the line isn't covered, a red dot says it's covered but at least one of the covering tests is failing, and a green dot means all the covering tests pass. It also calculates coverage statistics for you. Unfortunately, there's a couple of flaws in the coverage. Firstly, it doesn't support ExcludeFromCodeCoverage attributes. This feature has been requested and I expect will be included in a later release, but right now it doesn't. So this: ...is counted as a non-covered line, and drags your coverage statistics down. Hmph. As well as that, coverage of certain types of code is missed. This: ...is definitely covered. I am 100% absolutely certain it is, by several tests. NCrunch doesn't pick it up, down go my coverage statistics. I've had NCrunch find genuinely uncovered code which I've been able to remove, and that's great, but what's the coverage percentage on this project? Umm... I don't know. Conclusion None of these are major, tool-crippling problems, and I expect NCrunch to get much better in future releases. The current version has some great features, like this: ...that's a line of code with a failing test covering it, and NCrunch can run that failing test and take me to that line exquisitely easily. That's awesome! I'd happily pay for a tool that can do that. But here's the thing: NCrunch (currently) costs $159 (about £100) for a personal licence and $289 (about £180) for a commercial one. I'm not sure which one I'd need as my project is a personal one which I'm intending to open-source, but I'm a professional, self-employed developer, but in any case - that seems like a lot of money for an imperfect tool. If it did everything it's advertised to do more or less perfectly I'd consider it, but it doesn't. So no more NCrunch for me.

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• Collaborative Whiteboard using WebSocket in GlassFish 4 - Text/JSON and Binary/ArrayBuffer Data Transfer (TOTD #189)

  - by arungupta

  This blog has published a few blogs on using JSR 356 Reference Implementation (Tyrus) as its integrated in GlassFish 4 promoted builds. TOTD #183: Getting Started with WebSocket in GlassFish TOTD #184: Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark TOTD #185: Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket TOTD #186: Custom Text and Binary Payloads using WebSocket One of the typical usecase for WebSocket is online collaborative games. This Tip Of The Day (TOTD) explains a sample that can be used to build such games easily. The application is a collaborative whiteboard where different shapes can be drawn in multiple colors. The shapes drawn on one browser are automatically drawn on all other peer browsers that are connected to the same endpoint. The shape, color, and coordinates of the image are transfered using a JSON structure. A browser may opt-out of sharing the figures. Alternatively any browser can send a snapshot of their existing whiteboard to all other browsers. Take a look at this video to understand how the application work and the underlying code. The complete sample code can be downloaded here. The code behind the application is also explained below. The web page (index.jsp) has a HTML5 Canvas as shown: <canvas id="myCanvas" width="150" height="150" style="border:1px solid #000000;"></canvas> And some radio buttons to choose the color and shape. By default, the shape, color, and coordinates of any figure drawn on the canvas are put in a JSON structure and sent as a message to the WebSocket endpoint. The JSON structure looks like: { "shape": "square", "color": "#FF0000", "coords": { "x": 31.59999942779541, "y": 49.91999053955078 }} The endpoint definition looks like: @WebSocketEndpoint(value = "websocket",encoders = {FigureDecoderEncoder.class},decoders = {FigureDecoderEncoder.class})public class Whiteboard { As you can see, the endpoint has decoder and encoder registered that decodes JSON to a Figure (a POJO class) and vice versa respectively. The decode method looks like: public Figure decode(String string) throws DecodeException { try { JSONObject jsonObject = new JSONObject(string); return new Figure(jsonObject); } catch (JSONException ex) { throw new DecodeException("Error parsing JSON", ex.getMessage(), ex.fillInStackTrace()); }} And the encode method looks like: public String encode(Figure figure) throws EncodeException { return figure.getJson().toString();} FigureDecoderEncoder implements both decoder and encoder functionality but thats purely for convenience. But the recommended design pattern is to keep them in separate classes. In certain cases, you may even need only one of them. On the client-side, the Canvas is initialized as: var canvas = document.getElementById("myCanvas");var context = canvas.getContext("2d");canvas.addEventListener("click", defineImage, false); The defineImage method constructs the JSON structure as shown above and sends it to the endpoint using websocket.send(). An instant snapshot of the canvas is sent using binary transfer with WebSocket. The WebSocket is initialized as: var wsUri = "ws://localhost:8080/whiteboard/websocket";var websocket = new WebSocket(wsUri);websocket.binaryType = "arraybuffer"; The important part is to set the binaryType property of WebSocket to arraybuffer. This ensures that any binary transfers using WebSocket are done using ArrayBuffer as the default type seem to be blob. The actual binary data transfer is done using the following: var image = context.getImageData(0, 0, canvas.width, canvas.height);var buffer = new ArrayBuffer(image.data.length);var bytes = new Uint8Array(buffer);for (var i=0; i<bytes.length; i++) { bytes[i] = image.data[i];}websocket.send(bytes); This comprehensive sample shows the following features of JSR 356 API: Annotation-driven endpoints Send/receive text and binary payload in WebSocket Encoders/decoders for custom text payload In addition, it also shows how images can be captured and drawn using HTML5 Canvas in a JSP. How could this be turned in to an online game ? Imagine drawing a Tic-tac-toe board on the canvas with two players playing and others watching. Then you can build access rights and controls within the application itself. Instead of sending a snapshot of the canvas on demand, a new peer joining the game could be automatically transferred the current state as well. Do you want to build this game ? I built a similar game a few years ago. Do somebody want to rewrite the game using WebSocket APIs ? :-) Many thanks to Jitu and Akshay for helping through the WebSocket internals! Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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• Windows Phone 8 Launch Event Summary

  - by Tim Murphy

  Today was the official coming out party for Windows Phone 8.  Below is a summary of the launch event.  There is a lot here to stay with me. They started with a commercial staring Joe Belfiore show how his Windows Phone 8 was personal too him which highlights something I think Microsoft has done well over the last couple of event: spotlight how Windows Phone is a different experience from other smartphones.  Joe actually called iPhone and Android “tired old metaphors" and explained that the idea around Windows Phone was to “reinvent the smartphone around you” as “the most personal smartphone operating system”.  The is the message that they need to drive home in their adds. The only real technical aspect we found out was that they have optimized the operating system around the dual core Qualcomm Snapdragon chip set.  It seems like all of the other hardware goodies had already been announced.  The remainder of the event was centered around new features of the OS and app announcements. So what are we getting?  The integrated features included lock screen live tile, Data Sense, Rooms and Kids corner.  There wasn’t a lot of information about it, but Joe also talked about apps not just having live tiles, but being live apps that could integrate with wallet and the hub. The lock screen will now be able to be personalized with live tile data or even a photo slide show.  This gives the lock screen an even better ability to give you the information you want to know before you even unlock the phone. The Kids Corner allows you as a parent to setup an area on your phone that you kids can go into an use it without disturbing your apps.  They can play games or use apps that you have designated and will only see those apps.  It even has a special lock screen gesture just for the kids corner. Rooms allow you to organize your phone around the groups of people in your life.  You get a shared calendar, a room wall as well as shared notes beyond just being able to send messages to a group.  You can also invite people not on the Windows Phone platform to access an online version of the room. Data Sense is a new feature that gives you better control and understanding of your data plan usage.  You can see which applications are using data and it can automatically adjust they way your phone behaves as you get close to your data limit. Add to these features the fact that the entire Windows ecosystem is integrated with SkyDrive and you have an available anywhere experience that is unequaled by any other platform.  Your document, photos and music are available on your Windows Phone, Window 8 device and Xbox.  SkyDrive also doesn’t limit how long you can keep files like the competing cloud platforms and give more free storage. It was interesting the way they made the launch event more personal.  First Joe brought out his own kids to demo the Kids Corner.  They followed this up by bringing out Jessica Alba to discuss her experience on the Windows Phone 8.  They need to keep putting a face on the product instead of just showing features as a cold list. Then we get to apps.  We knew that the new Skype was coming, but we found out that it was created in such a way that it can receive calls without running consistently in the background which would eat up battery.  This announcement was follow by the coming Facebook app that is optimized for Windows Phone 8.  As a matter of fact they indicated that just after launch the marketplace would have 46 out of the top 50 apps used by all smartphone platforms.  In a rational world this tide with over 120,000 apps currently in the marketplace there should be no more argument about the Windows Phone ecosystem. For those of us who develop for Windows Phone and weren’t on the early adoption program will finally get access to the SDK tomorrow after an announcement at Build (more waiting).  Perhaps we will get a few new features then. In the end I wouldn’t say there were any huge surprises, but I am really excited about getting my hands on the devices next month and starting to develop.  Stay tuned. del.icio.us Tags: Windows Phone,Windows Phone 8,Winodws Phone 8 Launch,Joe Belfiore,Jessica Alba

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• Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket - (TOTD #185)

  - by arungupta

  The WebSocket API defines different send(xxx) methods that can be used to send text and binary data. This Tip Of The Day (TOTD) will show how to send and receive text and binary data using WebSocket. TOTD #183 explains how to get started with a WebSocket endpoint using GlassFish 4. A simple endpoint from that blog looks like: @WebSocketEndpoint("/endpoint") public class MyEndpoint { public void receiveTextMessage(String message) { . . . } } A message with the first parameter of the type String is invoked when a text payload is received. The payload of the incoming WebSocket frame is mapped to this first parameter. An optional second parameter, Session, can be specified to map to the "other end" of this conversation. For example: public void receiveTextMessage(String message, Session session) {     . . . } The return type is void and that means no response is returned to the client that invoked this endpoint. A response may be returned to the client in two different ways. First, set the return type to the expected type, such as: public String receiveTextMessage(String message) { String response = . . . . . . return response; } In this case a text payload is returned back to the invoking endpoint. The second way to send a response back is to use the mapped session to send response using one of the sendXXX methods in Session, when and if needed. public void receiveTextMessage(String message, Session session) {     . . .     RemoteEndpoint remote = session.getRemote();     remote.sendString(...);     . . .     remote.sendString(...);    . . .    remote.sendString(...); } This shows how duplex and asynchronous communication between the two endpoints can be achieved. This can be used to define different message exchange patterns between the client and server. The WebSocket client can send the message as: websocket.send(myTextField.value); where myTextField is a text field in the web page. Binary payload in the incoming WebSocket frame can be received if ByteBuffer is used as the first parameter of the method signature. The endpoint method signature in that case would look like: public void receiveBinaryMessage(ByteBuffer message) {     . . . } From the client side, the binary data can be sent using Blob, ArrayBuffer, and ArrayBufferView. Blob is a just raw data and the actual interpretation is left to the application. ArrayBuffer and ArrayBufferView are defined in the TypedArray specification and are designed to send binary data using WebSocket. In short, ArrayBuffer is a fixed-length binary buffer with no format and no mechanism for accessing its contents. These buffers are manipulated using one of the views defined by one of the subclasses of ArrayBufferView listed below: Int8Array (signed 8-bit integer or char) Uint8Array (unsigned 8-bit integer or unsigned char) Int16Array (signed 16-bit integer or short) Uint16Array (unsigned 16-bit integer or unsigned short) Int32Array (signed 32-bit integer or int) Uint32Array (unsigned 16-bit integer or unsigned int) Float32Array (signed 32-bit float or float) Float64Array (signed 64-bit float or double) WebSocket can send binary data using ArrayBuffer with a view defined by a subclass of ArrayBufferView or a subclass of ArrayBufferView itself. The WebSocket client can send the message using Blob as: blob = new Blob([myField2.value]);websocket.send(blob); where myField2 is a text field in the web page. The WebSocket client can send the message using ArrayBuffer as: var buffer = new ArrayBuffer(10);var bytes = new Uint8Array(buffer);for (var i=0; i<bytes.length; i++) { bytes[i] = i;}websocket.send(buffer); A concrete implementation of receiving the binary message may look like: @WebSocketMessagepublic void echoBinary(ByteBuffer data, Session session) throws IOException {    System.out.println("echoBinary: " + data);    for (byte b : data.array()) {        System.out.print(b);    }    session.getRemote().sendBytes(data);} This method is just printing the binary data for verification but you may actually be storing it in a database or converting to an image or something more meaningful. Be aware of TYRUS-51 if you are trying to send binary data from server to client using method return type. Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) TOTD #183 - Getting Started with WebSocket in GlassFish TOTD #184 - Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Custom payloads using encoder/decoder Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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• What Counts for A DBA: Observant

  - by drsql

  When walking up to the building where I work, I can see CCTV cameras placed here and there for monitoring access to the building. We are required to wear authorization badges which could be checked at any time. Do we have enemies?  Of course! No one is 100% safe; even if your life is a fairy tale, there is always a witch with an apple waiting to snack you into a thousand years of slumber (or at least so I recollect from elementary school.) Even Little Bo Peep had to keep a wary lookout.    We nerdy types (or maybe it was just me?) generally learned on the school playground to keep an eye open for unprovoked attack from simpler, but more muscular souls, and take steps to avoid messy confrontations well in advance. After we’d apprehensively negotiated adulthood with varying degrees of success, these skills of watching for danger, and avoiding it,  translated quite well to the technical careers so many of us were destined for. And nowhere else is this talent for watching out for irrational malevolence so appropriate as in a career as a production DBA.   It isn’t always active malevolence that the DBA needs to watch out for, but the even scarier quirks of common humanity.  A large number of the issues that occur in the enterprise happen just randomly or even just one time ever in a spurious manner, like in the case where a person decided to download the entire MSDN library of software, cross join every non-indexed billion row table together, and simultaneously stream the HD feed of 5 different sporting events, making the network access slow while the corporate online sales just started. The decent DBA team, like the going, gets tough under such circumstances. They spring into action, checking all of the sources of active information, observes the issue is no longer happening now, figures that either it wasn’t the database’s fault and that the reboot of the whatever device on the network fixed the problem.  This sort of reactive support is good, and will be the initial reaction of even excellent DBAs, but it is not the end of the story if you really want to know what happened and avoid getting called again when it isn’t even your fault.   When fires start raging within the corporate software forest, the DBA’s instinct is to actively find a way to douse the flames and get back to having no one in the company have any idea who they are.  Even better for them is to find a way of killing a potential problem while the fires are small, long before they can be classified as raging. The observant DBA will have already been monitoring the server environment for months in advance.  Most troubles, such as disk space and security intrusions, can be predicted and dealt with by alerting systems, whereas other trouble can come out of the blue and requires a skill of observing ongoing conditions and noticing inexplicable changes that could signal an emerging problem.  You can’t automate the DBA, because the bankable skill of a DBA is in detecting the early signs of unexpected problems, and working out how to deal with them before anyone else notices them.    To achieve this, the DBA will check the situation as it is currently happening,  and in many cases is likely to have been the person who submitted the problem to the level 1 support person in the first place, just to let the support team know of impending issues (always well received, I tell you what!). Database and host computer settings, configurations, and even critical data might be profiled and captured for later comparisons. He’ll use Monitoring tools, built-in, commercial (Not to be too crassly commercial or anything, but there is one such tool is SQL Monitor) and lots of homebrew monitoring tools to monitor for problems and changes in the server environment.   You will know that you have it right when a support call comes in and you can look at your monitoring tools and quickly respond that “response time is well within the normal range, the query that supports the failing interface works perfectly and has actually only been called 67% as often as normal, so I am more than willing to help diagnose the problem, but it isn’t the database server’s fault and is probably a client or networking slowdown causing the interface to be used less frequently than normal.” And that is the best thing for any DBA to observe…

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• Solaris 11.1 changes building of code past the point of __NORETURN

  - by alanc

  While Solaris 11.1 was under development, we started seeing some errors in the builds of the upstream X.Org git master sources, such as: "Display.c", line 65: Function has no return statement : x_io_error_handler "hostx.c", line 341: Function has no return statement : x_io_error_handler from functions that were defined to match a specific callback definition that declared them as returning an int if they did return, but these were calling exit() instead of returning so hadn't listed a return value. These had been generating warnings for years which we'd been ignoring, but X.Org has made enough progress in cleaning up code for compiler warnings and static analysis issues lately, that the community turned up the default error levels, including the gcc flag -Werror=return-type and the equivalent Solaris Studio cc flags -v -errwarn=E_FUNC_HAS_NO_RETURN_STMT, so now these became errors that stopped the build. Yet on Solaris, gcc built this code fine, while Studio errored out. Investigation showed this was due to the Solaris headers, which during Solaris 10 development added a number of annotations to the headers when gcc was being used for the amd64 kernel bringup before the Studio amd64 port was ready. Since Studio did not support the inline form of these annotations at the time, but instead used #pragma for them, the definitions were only present for gcc. To resolve this, I fixed both sides of the problem, so that it would work for building new X.Org sources on older Solaris releases or with older Studio compilers, as well as fixing the general problem before it broke more software building on Solaris. To the X.Org sources, I added the traditional Studio #pragma does_not_return to recognize that functions like exit() don't ever return, in patches such as this Xserver patch. Adding a dummy return statement was ruled out as that introduced unreachable code errors from compilers and analyzers that correctly realized you couldn't reach that code after a return statement. And on the Solaris 11.1 side, I updated the annotation definitions in <sys/ccompile.h> to enable for Studio 12.0 and later compilers the annotations already existing in a number of system headers for functions like exit() and abort(). If you look in that file you'll see the annotations we currently use, though the forms there haven't gone through review to become a Committed interface, so may change in the future. Actually getting this integrated into Solaris though took a bit more work than just editing one header file. Our ELF binary build comparison tool, wsdiff, actually showed a large number of differences in the resulting binaries due to the compiler using this information for branch prediction, code path analysis, and other possible optimizations, so after comparing enough of the disassembly output to be comfortable with the changes, we also made sure to get this in early enough in the release cycle so that it would get plenty of test exposure before the release. It also required updating quite a bit of code to avoid introducing new lint or compiler warnings or errors, and people building applications on top of Solaris 11.1 and later may need to make similar changes if they want to keep their build logs similarly clean. Previously, if you had a function that was declared with a non-void return type, lint and cc would warn if you didn't return a value, even if you called a function like exit() or panic() that ended execution. For instance: #include <stdlib.h> int callback(int status) { if (status == 0) return status; exit(status); } would previously require a never executed return 0; after the exit() to avoid lint warning "function falls off bottom without returning value". Now the compiler & lint will both issue "statement not reached" warnings for a return 0; after the final exit(), allowing (or in some cases, requiring) it to be removed. However, if there is no return statement anywhere in the function, lint will warn that you've declared a function returning a value that never does so, suggesting you can declare it as void. Unfortunately, if your function signature is required to match a certain form, such as in a callback, you not be able to do so, and will need to add a /* LINTED */ to the end of the function. If you need your code to build on both a newer and an older release, then you will either need to #ifdef these unreachable statements, or, to keep your sources common across releases, add to your sources the corresponding #pragma recognized by both current and older compiler versions, such as: #pragma does_not_return(exit) #pragma does_not_return(panic) Hopefully this little extra work is paid for by the compilers & code analyzers being able to better understand your code paths, giving you better optimizations and more accurate errors & warning messages.

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• State of the (Commerce) Union: What the healthcare.gov hiccups teach us about the commerce customer experience

  - by Katrina Gosek

  Guest Post by Brenna Johnson, Oracle Commerce Product A lot has been said about the healthcare.gov debacle in the last week. Regardless of your feelings about the Affordable Care Act, there’s a hidden issue in this story that most of the American people don’t understand: delivering a great commerce customer experience (CX) is hard. It shouldn’t be, but it is. The reality of the government’s issues getting the healthcare site up and running smooth is something we in the online commerce community know too well.  If there’s one thing the botched launch of the site has taught us, it’s that regardless of the size of your budget or the power of an executive with a high-profile project, some of the biggest initiatives with the most attention (and the most at stake) don’t go as planned. It may even give you a moment of solace – we have the same issues! But why?  Organizations engage too many separate vendors with different technologies, running sections or pieces of a site to get live. When things go wrong, it takes time to identify the problem – and who or what is at the center of it. Unfortunately, this is a brittle way of setting up a site, making it susceptible to breaks, bugs, and scaling issues. But, it’s the reality of running a site with legacy technology constraints in today’s demanding, customer-centric market. This approach also means there’s also a lot of cooks in lots of different kitchens. You’ve got development and IT, the business and the marketing team, an external Systems Integrator to bring it all together, a digital agency or consultant, QA, product experts, 3rd party suppliers, and the list goes on. To complicate things, different business units are held responsible for different pieces of the site and managing different technologies. And again – due to legacy organizational structure and processes, this is all accepted as the normal State of the Union. Digital commerce has been commonplace for 15 years. Yet, getting a site live, maintained and performing requires orchestrating a cast of thousands (or at least, dozens), big dollars, and some finger-crossing. But it shouldn’t. The great thing about the advent of mobile commerce and the continued maturity of online commerce is that it’s forced organizations to think from the outside, in. Consumers – whether they’re shopping for shoes or a new healthcare plan – don’t care about what technology issues or processes you have behind the scenes. They just want it to work.  They want their experience to be easy, fast, and tailored to them and their needs – whatever they are. This doesn’t sound like a tall order to the American consumer – especially since they interact with sites that do work smoothly.  But the reality is that it takes scores of people, teams, check-ins, late nights, testing, and some good luck to get sites to run, and even more so at Black Friday (or October 1st) traffic levels.  The last thing on a customer’s mind is making excuses for why they can’t buy a product – just get it to work. So what is the government doing? My guess is working day and night to get the site performing  - and having to throw big money at the problem. In the meantime they’re sending frustrated online users to the call center, or even a location where a trained “navigator” can help them in-person to complete their selection. Sounds a lot like multichannel commerce (where broken communication between siloed touchpoints will only frustrate the consumer more). One thing we’ve learned is that consumers spend their time and money with brands they know and trust. When sites are easy to use and adapt to their needs, they tend to spend more, come back, and even become long-time loyalists. Achieving this may require moving internal mountains, but there’s too much at stake to ignore the sea change in how organizations are thinking about their customer. If the thought of re-thinking your internal teams, technologies, and processes sounds like a headache, think about the pain associated with losing valuable customers – and dollars. Regardless if you’re in B2B or B2C, it’s guaranteed that your competitors are making CX a priority. Those early to the game who have made CX a priority have already begun to outpace their competition. So as you’re planning for 2014, look to the news this week. Make sure the customer experience is a focus at your organization. Expectations are at record highs. Map your customer’s journey, and think from the outside, in. How easy is it for your customers to do business with you? If they interact with many touchpoints across your organization, are the call center, website, mobile environment, or brick and mortar location in sync? Do you have the technology in place to achieve this? It’s time to give the people what they want!

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• Using XA Transactions in Coherence-based Applications

  - by jpurdy

  While the costs of XA transactions are well known (e.g. increased data contention, higher latency, significant disk I/O for logging, availability challenges, etc.), in many cases they are the most attractive option for coordinating logical transactions across multiple resources. There are a few common approaches when integrating Coherence into applications via the use of an application server's transaction manager: Use of Coherence as a read-only cache, applying transactions to the underlying database (or any system of record) instead of the cache. Use of TransactionMap interface via the included resource adapter. Use of the new ACID transaction framework, introduced in Coherence 3.6.   Each of these may have significant drawbacks for certain workloads. Using Coherence as a read-only cache is the simplest option. In this approach, the application is responsible for managing both the database and the cache (either within the business logic or via application server hooks). This approach also tends to provide limited benefit for many workloads, particularly those workloads that either have queries (given the complexity of maintaining a fully cached data set in Coherence) or are not read-heavy (where the cost of managing the cache may outweigh the benefits of reading from it). All updates are made synchronously to the database, leaving it as both a source of latency as well as a potential bottleneck. This approach also prevents addressing "hot data" problems (when certain objects are updated by many concurrent transactions) since most database servers offer no facilities for explicitly controlling concurrent updates. Finally, this option tends to be a better fit for key-based access (rather than filter-based access such as queries) since this makes it easier to aggressively invalidate cache entries without worrying about when they will be reloaded. The advantage of this approach is that it allows strong data consistency as long as optimistic concurrency control is used to ensure that database updates are applied correctly regardless of whether the cache contains stale (or even dirty) data. Another benefit of this approach is that it avoids the limitations of Coherence's write-through caching implementation. TransactionMap is generally used when Coherence acts as system of record. TransactionMap is not generally compatible with write-through caching, so it will usually be either used to manage a standalone cache or when the cache is backed by a database via write-behind caching. TransactionMap has some restrictions that may limit its utility, the most significant being: The lock-based concurrency model is relatively inefficient and may introduce significant latency and contention. As an example, in a typical configuration, a transaction that updates 20 cache entries will require roughly 40ms just for lock management (assuming all locks are granted immediately, and excluding validation and writing which will require a similar amount of time). This may be partially mitigated by denormalizing (e.g. combining a parent object and its set of child objects into a single cache entry), at the cost of increasing false contention (e.g. transactions will conflict even when updating different child objects). If the client (application server JVM) fails during the commit phase, locks will be released immediately, and the transaction may be partially committed. In practice, this is usually not as bad as it may sound since the commit phase is usually very short (all locks having been previously acquired). Note that this vulnerability does not exist when a single NamedCache is used and all updates are confined to a single partition (generally implying the use of partition affinity). The unconventional TransactionMap API is cumbersome but manageable. Only a few methods are transactional, primarily get(), put() and remove(). The ACID transactions framework (accessed via the Connection class) provides atomicity guarantees by implementing the NamedCache interface, maintaining its own cache data and transaction logs inside a set of private partitioned caches. This feature may be used as either a local transactional resource or as logging XA resource. However, a lack of database integration precludes the use of this functionality for most applications. A side effect of this is that this feature has not seen significant adoption, meaning that any use of this is subject to the usual headaches associated with being an early adopter (greater chance of bugs and greater risk of hitting an unoptimized code path). As a result, for the moment, we generally recommend against using this feature. In summary, it is possible to use Coherence in XA-oriented applications, and several customers are doing this successfully, but it is not a core usage model for the product, so care should be taken before committing to this path. For most applications, the most robust solution is normally to use Coherence as a read-only cache of the underlying data resources, even if this prevents taking advantage of certain product features.

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• Exploring TCP throughput with DTrace (2)

  - by user12820842

  Last time, I described how we can use the overlap in distributions of unacknowledged byte counts and send window to determine whether the peer's receive window may be too small, limiting throughput. Let's combine that comparison with a comparison of congestion window and slow start threshold, all on a per-port/per-client basis. This will help us Identify whether the congestion window or the receive window are limiting factors on throughput by comparing the distributions of congestion window and send window values to the distribution of outstanding (unacked) bytes. This will allow us to get a visual sense for how often we are thwarted in our attempts to fill the pipe due to congestion control versus the peer not being able to receive any more data. Identify whether slow start or congestion avoidance predominate by comparing the overlap in the congestion window and slow start distributions. If the slow start threshold distribution overlaps with the congestion window, we know that we have switched between slow start and congestion avoidance, possibly multiple times. Identify whether the peer's receive window is too small by comparing the distribution of outstanding unacked bytes with the send window distribution (i.e. the peer's receive window). I discussed this here. # dtrace -s tcp_window.d dtrace: script 'tcp_window.d' matched 10 probes ^C cwnd 80 10.175.96.92 value ------------- Distribution ------------- count 1024 | 0 2048 | 4 4096 | 6 8192 | 18 16384 | 36 32768 |@ 79 65536 |@ 155 131072 |@ 199 262144 |@@@ 400 524288 |@@@@@@ 798 1048576 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 3848 2097152 | 0 ssthresh 80 10.175.96.92 value ------------- Distribution ------------- count 268435456 | 0 536870912 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 5543 1073741824 | 0 unacked 80 10.175.96.92 value ------------- Distribution ------------- count -1 | 0 0 | 1 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 4 4096 | 9 8192 | 21 16384 | 36 32768 |@ 78 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 5391 131072 | 0 swnd 80 10.175.96.92 value ------------- Distribution ------------- count 32768 | 0 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 5543 131072 | 0 Here we are observing a large file transfer via http on the webserver. Comparing these distributions, we can observe: That slow start congestion control is in operation. The distribution of congestion window values lies below the range of slow start threshold values (which are in the 536870912+ range), so the connection is in slow start mode. Both the unacked byte count and the send window values peak in the 65536-131071 range, but the send window value distribution is narrower. This tells us that the peer TCP's receive window is not closing. The congestion window distribution peaks in the 1048576 - 2097152 range while the receive window distribution is confined to the 65536-131071 range. Since the cwnd distribution ranges as low as 2048-4095, we can see that for some of the time we have been observing the connection, congestion control has been a limiting factor on transfer, but for the majority of the time the receive window of the peer would more likely have been the limiting factor. However, we know the window has never closed as the distribution of swnd values stays within the 65536-131071 range. So all in all we have a connection that has been mildly constrained by congestion control, but for the bulk of the time we have been observing it neither congestion or peer receive window have limited throughput. Here's the script: #!/usr/sbin/dtrace -s tcp:::send / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @cwnd["cwnd", args[4]-tcp_sport, args[2]-ip_daddr] = quantize(args[3]-tcps_cwnd); @ssthresh["ssthresh", args[4]-tcp_sport, args[2]-ip_daddr] = quantize(args[3]-tcps_cwnd_ssthresh); @unacked["unacked", args[4]-tcp_sport, args[2]-ip_daddr] = quantize(args[3]-tcps_snxt - args[3]-tcps_suna); @swnd["swnd", args[4]-tcp_sport, args[2]-ip_daddr] = quantize((args[4]-tcp_window)*(1 tcps_snd_ws)); } One surprise here is that slow start is still in operation - one would assume that for a large file transfer, acknowledgements would push the congestion window up past the slow start threshold over time. The slow start threshold is in fact still close to it's initial (very high) value, so that would suggest we have not experienced any congestion (the slow start threshold is adjusted when congestion occurs). Also, the above measurements were taken early in the connection lifetime, so the congestion window did not get a changes to get bumped up to the level of the slow start threshold. A good strategy when examining these sorts of measurements for a given service (such as a webserver) would be start by examining the distributions above aggregated by port number only to get an overall feel for service performance, i.e. is congestion control or peer receive window size an issue, or are we unconstrained to fill the pipe? From there, the overlap of distributions will tell us whether to drill down into specific clients. For example if the send window distribution has multiple peaks, we may want to examine if particular clients show issues with their receive window.

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• Jini : single server with multiple clients

  - by user200340

  Hi all, I have a question about how to make multiple clients can access a single file located on server side and keep the file consistent. I have a simple PhoneBook server-client Jini program running at the moment, and server only provides some getter functions to clients, such as getName(String number), getNumber(String name) from a PhoneBook class(serializable), phonebook data are stored in a text file (phonebook.txt) at the moment. I have tried to implement some functions allowing to write a new records into the phonebook.txt file. If the writing record (name) is existing, an integer number will be added into the writing record. for example the existing phonebook.txt is .... John 01-01010101 .... if the writing record is "John 01-12345678",then "John_1 01-12345678" will be writen into phonebook.txt However, if i start with two clients A and B (on the same machine using localhost), and A tries to write "John 01-11111111", B tries to write "John 01-22222222". The early record will be overwritten later record. So, there must be something i did complete wrong. My client and server code are just like Jini HelloWorld example. My server side code is . 1. LookupDiscovery with parameter new String[]{""}; 2. DiscoveryListener for LookupDiscovery 3. registrations are saved into a HashTable 4. for every discovered lookup service, i use registrar to register the ServiceItem, ServiceItem contains a null attributeSets, a null serviceId, and a service. The client code has: 1. LookupDiscovery with parameter new String[]{""}; 2. DiscoveryListener for LookupDiscovery 3. a ServiceTemplate with null attributeSets, a null serviceId and a type, the type is the interface class. 4. for each found ServiceRegistrar, if it can find the looking for ServiceTemplate, the returned Object is cast into the type of the interface class. I have tried to google more details, and i found JavaSpace could be the one i missed. But i am still not sure about it (i only start Jini for a very short time). So any help would be greatly appreciated.

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• Problems with makeObjectsPerformSelector inside and outside a class?

  - by QuakAttak

  A friend and I are creating a card game for the iPhone, and in these early days of the project, I'm developing a Deck class and a Card class to keep up with the cards. I'm wanting to test the shuffle method of the Deck class, but I am not able to show the values of the cards in the Deck class instance. The Deck class has a NSArray of Card objects that have a method called displayCard that shows the value and suit using console output(printf or NSLog). In order to show what cards are in a Deck instance all at once, I am using this, [deck makeObjectsPerformSelector:@selector(displayCard)], where deck is the NSArray in the Deck class. Inside of the Deck class, nothing is displayed on the console output. But in a test file, it works just fine. Here's the test file that creates its own NSArray: #import <Foundation/Foundation.h> #import "card.h" int main (int argc, char** argv) { NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init]; Card* two = [[Card alloc] initValue:2 withSuit:'d']; Card* three = [[Card alloc] initValue:3 withSuit:'h']; Card* four = [[Card alloc] initValue:4 withSuit:'c']; NSArray* deck = [NSArray arrayWithObjects:two,three,four,nil]; //Ok, what if we release the objects in the array before they're used? //I don't think this will work... [two release]; [three release]; [four release]; //Ok, it works... I wonder how... //Hmm... how will this work? [deck makeObjectsPerformSelector:@selector(displayCard)]; //Yay! It works fine! [pool release]; return 0; } This worked beautifully, so I created an initializer around this idea, creating 52 card objects one at a time and adding them to the NSArray using deck = [deck arrayByAddingObject:newCard]. Is the real problem with how I'm using makeObjectsPerformSelector or something before/after it?

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• Using Apple’s Bonjour service from .NET?

  - by Martín Marconcini

  I have an iPhone app that publishes through Bonjour. The Mac counterpart works, they sync and exchange data. Now I have to port that little Mac app to Windows. I’ve decided to go with .NET (because that’s what I know). The app is not complex, but I’m in the early stages. I need to browse/discover Bonjour services. For this task, I’ve downloaded Mono.Zeroconf and Apple’s latest SDK (which includes a couple of C# Samples). I’m not really pasting code because I’m really copy/pasting the samples. In fact, Mono.Zeroconf has a MZClient.exe that can be used to test “all the API”. My 1st test was -on the same box- open two cmd.exe and launch a MZclient registering a service and on the other, launch it and “discover it”. It doesn’t work. Here’s the server: C:\MZ>MZClient -v -p "_http._tcp 80 mysimpleweb” *** Registering name = 'mysimpleweb', type = '_http._tcp', domain = 'local.' *** Registered name = ‘mysimpleweb’ On the other terminal: c:\MZ>MZClient -v -t "_http._tcp" Creating a ServiceBrowser with the following settings: Interface = 0 (All) Address Protocol = Any Domain = local Registration Type = _http._tcp Resolve Shares = False Hit ^C when you're bored waiting for responses. And that’s it. Nothing happens. I’ve of course tried with different services to no avail. Even played a little bit with that domain thing. Remember this is the same box. I tried on another computer, because this was a VM inside OSX, so I went ahead and tried on a “pure” win XP. Nothing. note: I have Apple Bonjour Service (up and running) and also the Apple SDK (installed later). Given that this didn’t work, I went ahead and decided to try the Apple SDK which has an Interop and a few pre-compiled samples (and its source code). Short story, neither the mDSNBrowser.exe nor the SimpleChat.exe work/see/discover anything. My box is a Win7 under Parallels, but that doesn’t seem to be affecting anything, given that the native XP exhibits the same problems. What am I doing so awfully wrong?

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• ClassCastException when casting custom View subclass

  - by Jens Jacob

  Hi I've run into an early problem with developing for android. I've made my own custom View (which works well). In the beginning i just added it to the layout programmatically, but i figured i could try putting it into the XML layout instead (for consistency). So what i got is this: main.xml: [...] <sailmeter.gui.CompassView android:id="@+id/compassview1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/widget55" android:background="@color/white" /> [...] CompassView.java: public class CompassView extends View { } SailMeter.java (activity class): public class SailMeter extends Activity implements PropertyChangeListener { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); compassview = (CompassView) findViewById(R.id.compassview1); [...] } } (Theres obviously more, but you get the point) Now, this is the stacktrace: 05-23 16:32:01.991: ERROR/AndroidRuntime(10742): Uncaught handler: thread main exiting due to uncaught exception 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): java.lang.RuntimeException: Unable to start activity ComponentInfo{sailmeter.gui/sailmeter.gui.SailMeter}: java.lang.ClassCastException: android.view.View 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2596) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.app.ActivityThread.access$2200(ActivityThread.java:126) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1932) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.os.Handler.dispatchMessage(Handler.java:99) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.os.Looper.loop(Looper.java:123) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.app.ActivityThread.main(ActivityThread.java:4595) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at java.lang.reflect.Method.invokeNative(Native Method) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at java.lang.reflect.Method.invoke(Method.java:521) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at dalvik.system.NativeStart.main(Native Method) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): Caused by: java.lang.ClassCastException: android.view.View 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at sailmeter.gui.SailMeter.onCreate(SailMeter.java:51) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2544) 05-23 16:32:02.051: ERROR/AndroidRuntime(10742): ... 11 more Why cant i cast my custom view? I need it to be that type since it has a few extra methods in it that i want to access. Should i restructure it and have another class handle the logic, and then just having the view being a view? Thanks for any help.

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• WPF DataTemplates with VS2010 designer support + reusable - would you do it that way?

  - by Christian

  Ok, I am currently tidying up all my old stuff. I ran into the issue of "code only DataTemplates" - which are really a pain in the ass. You can't see anything, they are really hard to design, and I want to improve my project. So I had the idea to use the following solution. The main benefits are: You have designer support for your data template You can easily include example sample data The file naming is consistent and easy to remember The preview does not require an additional XAML wrapper (even with code only controls) I will try to explain and illustrate my solution using a few pictures. I am interested in feedback, especially if you can imagine a better way to do it. And, of course, if you see any maintenance or performance issues. Ok, lets start with a simple PreviewObject. I want to have some data in it, so I create a subclass which will automatically fill in some dummy data. Then I add a list to the control, and name this list. Afterwards I add a DataTemplate, this is the sole reason for the whole control (to be able to see and edit the DataTemplate in place): Now I use this control to get my DataTemplate, to use it in other places. To make this easier, I added some code in the code behind, see here: Now I want a control to show me a list of PreviewItems, so I created a "code-only" control which creates an instance of my service (or gets one using DI in real world) and fills its list box with it: To view the result of this work, I added this control inside the same named XAML, this is basically only to be able to see the final result: What I do not like in this solution: The need to create the last control in "code only". So I tried something different while writing this post. The following two screenshots illustrate the approach. I am creating an instance of the service inside the DataContext, and I am using bindings to supply the Itemssourc and the ItemTemplate. The reason for the strange "static property" is refactoring support. If I hardcode the path in the designer (e.g. using "Path = PreviewHistory") and I refactor the names (which happens quite often, early design phase) - I screw up my controls without realizing it. Does anyone has a better idea for this? I am using Resharper, btw. Thanks for any input, and sorry for the image overkill. Just easier to explain that way.. Chris

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• Is this slow WPF TextBlock performance expected?

  - by Ben Schoepke

  Hi, I am doing some benchmarking to determine if I can use WPF for a new product. However, early performance results are disappointing. I made a quick app that uses data binding to display a bunch of random text inside of a list box every 100 ms and it was eating up ~15% CPU. So I made another quick app that skipped the data binding/data template scheme and does nothing but update 10 TextBlocks that are inside of a ListBox every 100 ms (the actual product wouldn't require 100 ms updates, more like 500 ms max, but this is a stress test). I'm still seeing ~10-15% CPU usage. Why is this so high? Is it because of all the garbage strings? Here's the XAML: <Grid> <ListBox x:Name="numericsListBox"> <ListBox.Resources> <Style TargetType="TextBlock"> <Setter Property="FontSize" Value="48"/> <Setter Property="Width" Value="300"/> </Style> </ListBox.Resources> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> </ListBox> </Grid> Here's the code behind: public partial class Window1 : Window { private int _count = 0; public Window1() { InitializeComponent(); } private void OnLoad(object sender, RoutedEventArgs e) { var t = new DispatcherTimer(TimeSpan.FromSeconds(0.1), DispatcherPriority.Normal, UpdateNumerics, Dispatcher); t.Start(); } private void UpdateNumerics(object sender, EventArgs e) { ++_count; foreach (object textBlock in numericsListBox.Items) { var t = textBlock as TextBlock; if (t != null) t.Text = _count.ToString(); } } } Any ideas for a better way to quickly render text? My computer: XP SP3, 2.26 GHz Core 2 Duo, 4 GB RAM, Intel 4500 HD integrated graphics. And that is an order of magnitude beefier than the hardware I'd need to develop for in the real product.

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