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  • GPL vs plugin interfaces not designed with a specific application in mind

    - by Kristóf Marussy
    I am not seeking or in need of legal advice, but an interesting though experiment came to my mind. Imagine the following situtation (I cannot really think about a concrete example and I am unsure if a real manifestation even exists): there is a free (libre) api A licensed under some permissive license or even LGPL. Non-free application B implements this api in order host plugins, but there are other free software doing the same thing. Moreover, there is plugin C acting as a plugin under api A. It links to library D, that is under GPL, so C is also under GPL. Plugins using A are loaded into hosts via a dlopen-like mechanism and use complex data structure for host-plugin communication. Neither B nor C distribute any files that may be required for A to function properly (like headers containing the structure definitions of A or dynamic libraries containing helper functions for A written by the authors of A), but such things may exist. Now some user installs application B and plugin C on his machine, along with anything that may be required for api A to function properly. Then he proceeds and loads C into B and creates some intellectual property with B which is not a piece of software. Did a GPL violation happend at some point, and if so, who violated GPL and why? The authors of C violate D's license by making C possible to be used in non-free host B? This is a possibility because they can't give and exception of GPL (like one described in http://www.gnu.org/licenses/gpl-faq.html#GPLPluginsInNF or http://www.gnu.org/licenses/gpl-faq.html#LinkingOverControlledInterface) due to D's license terms. The authors of B violate C's and D's license by making C possible to be loaded in B? This is a possibility because http://www.gnu.org/licenses/gpl-faq.html#NFUseGPLPlugins disallows the mechanisms A uses for communitation between the free and non-free modules. The authors of A, because the api may be used (and in this case, was used) for communication between GPL'd and non-free software. This would be extremely absurd. The user, because at the moment of loading B into C, he made a derived work of C. I think this is impossible, because he does not distribute it. But would the situation change is he decided to release a configuration file of B which makes B load C as a plugin? Nobody, because A counts as a 'system library', and both B and C directly interact only with A, not eachother. In a sane world, this would happen... A concrete example of A could be some kind of audio (think LADSPA) or image processing api. However, I could find no such interface (that is free software, generic and is also implemented by commercial tools). A real-world example could also be quite enlightening.

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  • The SPARC SuperCluster

    - by Karoly Vegh
    Oracle has been providing a lead in the Engineered Systems business for quite a while now, in accordance with the motto "Hardware and Software Engineered to Work Together." Indeed it is hard to find a better definition of these systems.  Allow me to summarize the idea. It is:  Build a compute platform optimized to run your technologies Develop application aware, intelligently caching storage components Take an impressively fast network technology interconnecting it with the compute nodes Tune the application to scale with the nodes to yet unseen performance Reduce the amount of data moving via compression Provide this all in a pre-integrated single product with a single-pane management interface All these ideas have been around in IT for quite some time now. The real Oracle advantage is adding the last one to put these all together. Oracle has built quite a portfolio of Engineered Systems, to run its technologies - and run those like they never ran before. In this post I'll focus on one of them that serves as a consolidation demigod, a multi-purpose engineered system.  As you probably have guessed, I am talking about the SPARC SuperCluster. It has many great features inherited from its predecessors, and it adds several new ones. Allow me to pick out and elaborate about some of the most interesting ones from a technological point of view.  I. It is the SPARC SuperCluster T4-4. That is, as compute nodes, it includes SPARC T4-4 servers that we learned to appreciate and respect for their features: The SPARC T4 CPUs: Each CPU has 8 cores, each core runs 8 threads. The SPARC T4-4 servers have 4 sockets. That is, a single compute node can in parallel, simultaneously  execute 256 threads. Now, a full-rack SPARC SuperCluster has 4 of these servers on board. Remember the keyword demigod.  While retaining the forerunner SPARC T3's exceptional throughput, the SPARC T4 CPUs raise the bar with single performance too - a humble 5x better one than their ancestors.  actually, the SPARC T4 CPU cores run in both single-threaded and multi-threaded mode, and switch between these two on-the-fly, fulfilling not only single-threaded OR multi-threaded applications' needs, but even mixed requirements (like in database workloads!). Data security, anyone? Every SPARC T4 CPU core has a built-in encryption engine, that is, encryption algorithms cast into silicon.  A PCI controller right on the chip for customers who need I/O performance.  Built-in, no-cost Virtualization:  Oracle VM for SPARC (the former LDoms or Logical Domains) is not a server-emulation virtualization technology but rather a serverpartitioning one, the hypervisor runs in the server firmware, and all the VMs' HW resources (I/O, CPU, memory) are accessed natively, without performance overhead.  This enables customers to run a number of Solaris 10 and Solaris 11 VMs separated, independent of each other within a physical server II. For Database performance, it includes Exadata Storage Cells - one of the main reasons why the Exadata Database Machine performs at diabolic speed. What makes them important? They provide DB backend storage for your Oracle Databases to run on the SPARC SuperCluster, that is what they are built and tuned for DB performance.  These storage cells are SQL-aware.  That is, if a SPARC T4 database compute node executes a query, it doesn't simply request tons of raw datablocks from the storage, filters the received data, and throws away most of it where the statement doesn't apply, but provides the SQL query to the storage node too. The storage cell software speaks SQL, that is, it is able to prefilter and through that transfer only the relevant data. With this, the traffic between database nodes and storage cells is reduced immensely. Less I/O is a good thing - as they say, all the CPUs of the world do one thing just as fast as any other - and that is waiting for I/O.  They don't only pre-filter, but also provide data preprocessing features - e.g. if a DB-node requests an aggregate of data, they can calculate it, and handover only the results, not the whole set. Again, less data to transfer.  They support the magical HCC, (Hybrid Columnar Compression). That is, data can be stored in a precompressed form on the storage. Less data to transfer.  Of course one can't simply rely on disks for performance, there is Flash Storage included there for caching.  III. The low latency, high-speed backbone network: InfiniBand, that interconnects all the members with: Real High Speed: 40 Gbit/s. Full Duplex, of course. Oh, and a really low latency.  RDMA. Remote Direct Memory Access. This technology allows the DB nodes to do exactly that. Remotely, directly placing SQL commands into the Memory of the storage cells. Dodging all the network-stack bottlenecks, avoiding overhead, placing requests directly into the process queue.  You can also run IP over InfiniBand if you please - that's the way the compute nodes can communicate with each other.  IV. Including a general-purpose storage too: the ZFSSA, which is a unified storage, providing NAS and SAN access too, with the following features:  NFS over RDMA over InfiniBand. Nothing is faster network-filesystem-wise.  All the ZFS features onboard, hybrid storage pools, compression, deduplication, snapshot, replication, NFS and CIFS shares Storageheads in a HA-Cluster configuration providing availability of the data  DTrace Live Analytics in a web-based Administration UI Being a general purpose application data storage for your non-database applications running on the SPARC SuperCluster over whichever protocol they prefer, easily replicating, snapshotting, cloning data for them.  There's a lot of great technology included in Oracle's SPARC SuperCluster, we have talked its interior through. As for external scalability: you can start with a half- of full- rack SPARC SuperCluster, and scale out to several racks - that is, stacking not separate full-rack SPARC SuperClusters, but extending always one large instance of the size of several full-racks. Yes, over InfiniBand network. Add racks as you grow.  What technologies shall run on it? SPARC SuperCluster is a general purpose scaleout consolidation/cloud environment. You can run Oracle Databases with RAC scaling, or Oracle Weblogic (end enjoy the SPARC T4's advantages to run Java). Remember, Oracle technologies have been integrated with the Oracle Engineered Systems - this is the Oracle on Oracle advantage. But you can run other software environments such as SAP if you please too. Run any application that runs on Oracle Solaris 10 or Solaris 11. Separate them in Virtual Machines, or even Oracle Solaris Zones, monitor and manage those from a central UI. Here the key takeaways once again: The SPARC SuperCluster: Is a pre-integrated Engineered System Contains SPARC T4-4 servers with built-in virtualization, cryptography, dynamic threading Contains the Exadata storage cells that intelligently offload the burden of the DB-nodes  Contains a highly available ZFS Storage Appliance, that provides SAN/NAS storage in a unified way Combines all these elements over a high-speed, low-latency backbone network implemented with InfiniBand Can grow from a single half-rack to several full-rack size Supports the consolidation of hundreds of applications To summarize: All these technologies are great by themselves, but the real value is like in every other Oracle Engineered System: Integration. All these technologies are tuned to perform together. Together they are way more than the sum of all - and a careful and actually very time consuming integration process is necessary to orchestrate all these for performance. The SPARC SuperCluster's goal is to enable infrastructure operations and offer a pre-integrated solution that can be architected and delivered in hours instead of months of evaluations and tests. The tedious and most importantly time and resource consuming part of the work - testing and evaluating - has been done.  Now go, provide services.   -- charlie  

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  • How can I evaluate a candidate's knowledge of Html/CSS during an interview?

    - by webnoob
    I am trying to determine some good interview questions to assess the ability of people coming in for a Html/CSS job, however that topic is extremely broad, and I'm not sure what sort of questions I can ask to properly evaluate someone's HTML/CSS knowledge. What sort of questions can I ask to evaluate a candidate's Html/CSS abilities during an interview? Ideally I would like to ask few questions and then give them a real life scenario to combat.

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  • Oracle Announces Oracle Data Integrator 12c and Oracle GoldenGate 12c

    - by Roxana Babiciu
    In today’s data-driven business environment, organizations need to cost-effectively manage the ever-growing streams of information originating both inside and outside the firewall and address emerging deployment styles like cloud, big data analytics, and real-time replication. To help customers succeed, Oracle is enhancing its data integration offering with Oracle Data Integrator 12c and Oracle GoldenGate 12c. These flexible and comprehensive solutions help customers capitalize on their data to reduce costs and drive business growth. Read more here

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  • How to create posts in asp.net ..?? [closed]

    - by ntechi
    I am doing my final year project and have decided to make a website in asp.net. For that I'll be using Micrsoft Visual Studio 2008. I'm making a Real ESTATE properties website. I want to know how to create posts in asp.net( like in WORDPRESS) and also when I hit SEARCH it should search for the desired keyword or the searched post. If post is not possible then it should display pages....Please help as I'm a beginner..

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  • Oracle Database 11g Upgrade Webcast with Roy Swonger now On Demand

    - by margaret hamburger
    Don't worry if you missed our LIVE webcast  ' Three Compelling Reasons to Upgrade to Oracle Database 11g ' with Database Upgrade expert Roy Swonger.  You can now register for the On-Demand version to learn about Oracle Database 11g upgrade best practices with real customer examples. You'll get access to loads of great upgrade resources for making database upgrades faster and easier. You can also download a copy of our webcast presentation, so register now.

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  • What does your University 1st class mean?

    - by Abimaran
    I know, it's highly subjective question, but, I need the opinion. Please don't close this! IMHO and experience, they (the 1st class fellows) have a the resources (tutorials, past papers, etc), courage and the ability to memorize the answers on that. But, there are some talented peoples, who have the real knowledge with the 1st class. Are those peoples really win in the industries? Please don't ask my class :)

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  • SQL Solstice

    - by andyleonard
    Introduction My friends in North Carolina have decided to create a new event called SQL Solstice . Details: 18 - 20 Aug 2011 Holiday Inn Brownstone & Conference Center 1707 Hillsborough Street - Raleigh, NC 27605 Toll Free 800-331-7919 18 Aug - A Day of Deep Dives ($259) Day-long presentations delivered by folks with real-world, hands-on experience. Louis Davidson on Database Design Andrew Kelly on Performance Tuning Jessica M. Moss on Reporting Services Ed Wilson on Powershell (me) on SSIS 19...(read more)

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  • Algorithm for approximating sihlouette image as polygon

    - by jack
    I want to be able to analyze a texture in real time and approximate a polygon to represent a silhouette. Imagine a person standing in front of a green screen and I want to approximately trace around their outline and get a 2D polygon as the result. Are there algorithms to do this and are they fast enough to work frame-to-frame in a game? (I have found algorithms to triangulate polygons, but I am having trouble knowing what to search for that describes my goal.)

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  • Inserting data to database from Android

    - by Angel
    I have to build an application where the requirement is that my clients will send data from their Android device and I have to save that data to a database. I have done the part of coding that inserts data from Android emulator to my XAMPP database on localhost, now I have to implement the real thing. How can I connect the devices where my application will be installed to the XAMPP database I have created so that the data they send can be inserted into it?

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  • Learning how to integrate JavaScript with other languages

    - by beacon
    After learning JavaScript syntax, what are some good resources for learning about integrating JavaScript with other languages (HTML, XML, CSS, PHP) to create real, useful applications? I'm most interested in reading articles or other people's code - not so interested in books. Basically, I'm looking to move from programming puzzle-solvers to programming complex applications and could use some advice.

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  • Speaking at Mix11

    - by Dennis Vroegop
    In April Microsoft will hold the next MIX event. MIX was usually targeted at web designers and developers but has grown over the years to be more a general conference focused on the web and devices. In other words: everything the normal consumer might encounter. It’s not your typical developers conference, although you’ll find many developers there as well. But next to the developers you’ll probably run into designers and user experience specialists as well. This year I am proud to say that I will be one of the people presenting there. Together with all the Surface MVP’s in the world (sounds impressive, but there are only 7 of us) we’ll host a panel discussion on all things Surface, NUI and everything else that matches those subjects. Here’s what the abstract says: The Natural User Interface (NUI) is a hot topic that generates a lot of excitement, but there are only a handful of companies doing real innovation with NUIs and most of the practical experience in the NUI style of design and development is limited to a small number of experts. The Microsoft Surface MVPs are a subset of these experts that have extensive real-world experience with Microsoft Surface and other NUI devices. This session is a panel featuring the Microsoft Surface MVPs and an unfiltered discussion with each other and the audience about the state of the art in NUI design and development. We will share our experiences and ideas, discuss what we think NUI will look like in the near future, and back up our statements with cutting-edge demonstrations prepared by the panelists involving combinations of Microsoft Surface 2.0, Kinect, and Windows Phone 7. We, as Surface MVPs think we are more than just Surface oriented. We like to think we are more NUI MVP’s. But since that’s not a technology with Microsoft you can’t actually become a NUI MVP so Surface is the one that comes the closest. We are currently working on the details of our session but believe me: it will blow you away. Several people we talked to have said this could potentially be the best session of Mix. Quite a challenge, but we’re up for it! Of course I won’t be telling you exactly what we’re going to do in Las Vegas but rest assured that when you visit our session you’ll leave with a lot of new ideas and hopefully be inspired to bring into practice what you’ve seen. Even if the technology we’ll show you isn’t readily available yet. So, if you are in Las Vegas between April 12th and 14th, please join Joshua Blake, Neil Roodyn, Rick Barraza, Bart Roozendaal, Josh Santangelo, Nicolas Calvi and myself for some NUI fun! See you in Vegas! Tags van Technorati: mix11,las vegas,surface,nui,kinecct

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  • What is enterprise software, exactly?

    - by good_computer
    I don't understand the difference between "normal" software and enterprise software. Even after reading these... "Enterprise Software" on Wikipedia "Enterprise Software Is Sexy Again" on Techcrunch "The Great Enterprise Software Swindle" on Coding Horror I can't really wrap my head around the real differences. Is there any difference at all between the two? Why do people say enterprise software sucks?

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  • SQL Server Training in the UK–SSIS, MDX, Admin, MDS, Internals

    - by simonsabin
    If you are looking for SQL Server training they there is no better place to start than a new company Technitrain Its been setup by a fellow MVP and SQLBits Organiser Chris Webb. Why this company rather than any others? Training based on real world experience by the best in the business. The key to Technitrain’s model is not to cram the shelves high with courses and get some average Joe trainers to deliver them. Technitrain bring in world renowned experts in their fields to deliver courses written...(read more)

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  • Open Source AI Bot interfaces

    - by David Young
    What are some open source AI Bot interfaces? Similar to Pogamut 3 GameBots2004 for custom Unreal Tournament bots or Brood Wars API for Starcraft bots etc. If you could please post one AI bot interface per answer (make sure to provide a link) and give a brief summary as to the content of the blog posts. Please include what type of bot interface structure it is, client/server, server/server, etc e.g. BWAPI is client/server which emulates a real player

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  • wave-vs.net

    - by Sean Feldman
    This is an interesting plug-in for VS.NET 2008/2010 to allow remote pair-programming. I’m a big advocate for pair-programming and collaborative work, so this plug-in has its place in the real world. I used to pair-program with a developer that was remote, and we used VNC/RDC, but this one is way better.

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  • "Building on a Solid Foundation"

    Designing the right IT infrastructure is a critical part of ensuring application availability and performance. See how companies rely on an Oracle grid infrastructure—including Oracle Database and Oracle Real Application Clusters—to provide a solid yet flexible base for their applications.

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  • DRBD and MySQL - Virtualbox Setup

    DRBD is a Linux project that provides a real-time distributed filesystem. Sean Hull demonstrates how to use Sun's virtualbox software to create a pair of VMs, then configure those VMs with DRBD, and finally install and test MySQL running on volumes sitting on DRBD.

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  • DRBD and MySQL - Virtualbox Setup

    DRBD is a Linux project that provides a real-time distributed filesystem. Sean Hull demonstrates how to use Sun's virtualbox software to create a pair of VMs, then configure those VMs with DRBD, and finally install and test MySQL running on volumes sitting on DRBD.

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  • Attunity Oracle CDC Solution for SSIS - Beta

    We in no way work for Attunity but we were asked to test drive a beta version of their Oracle CDC solution for SSIS.  Everybody should know that moving more data than you need to takes too much time and uses resources that may better be employed doing something else.  Change data Capture is a technology that is designed to help you identify only the data that has had something done to it and you can therefore move only what is needed.  Microsoft have implemented this exact functionality into SQL server 2008 and I really like it there.  Attunity though are doing it on Oracle. DISCLAIMER: This is a BETA release and some of the parts are a bit ugly/difficult to work with.  The idea though is definitely right and the product once working does exactly what it says on the tin.  They have always been helpful to me when I have had a problem with the product and if that continues then beta testing pain should be eased somewhat. In due course I am going to be doing some videos around me using the product.  If you use Oracle and SSIS then give it a go. Here is their product description.   Attunity is a Microsoft SQL Server technology partner and the creator of the Microsoft Connectors for Oracle and Teradata, currently available in SQL Server 2008 Enterprise Edition. Attunity released a beta version of the Attunity Oracle-CDC for SSIS, a product that integrates continually changing Oracle data into SSIS, efficiently and in real-time. Attunity designed the product and integrated it into SSIS to create the simple creation of change data capture (CDC) solutions, accelerate implementation time, and reduce resources and costs. They also utilize log-based CDC so the solution has minimal impact on the Oracle source system. You can use the product to implement enterprise-class data replication, synchronization, and real-time business intelligence (BI) and data warehousing projects, quickly and efficiently, leveraging their existing SQL Server investments and resource skills. Attunity architected the product specifically for the Microsoft SSIS developer community and the product is available for both SQL Server 2005 and SQL Server 2008. It offers the following key capabilities: · Log-based, non-intrusive Oracle CDC · Full integration into SSIS and the Business Intelligence Developer Studio · Automatic generation of SSIS packages for CDC as well as full-loads of Oracle data · Filtering of Oracle tables and columns at the source · Monitoring and control of CDC processing Click to learn more and download the beta.

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  • Consuming the Amazon S3 service from a Win8 Metro Application

    - by cibrax
    As many of the existing Http APIs for Cloud Services, AWS also provides a set of different platform SDKs for hiding many of complexities present in the APIs. While there is a platform SDK for .NET, which is open source and available in C#, that SDK does not work in Win8 Metro Applications for the changes introduced in WinRT. WinRT offers a complete different set of APIs for doing I/O operations such as doing http calls or using cryptography for signing or encrypting data, two aspects that are absolutely necessary for consuming AWS. All the I/O APIs available as part of WinRT are asynchronous, and uses the TPL model for .NET applications (HTML and JavaScript Metro applications use a model based in promises, which is similar concept).  In the case of S3, the http Authorization header is used for two purposes, authenticating clients and make sure the messages were not altered while they were in transit. For doing that, it uses a signature or hash of the message content and some of the headers using a symmetric key (That's just one of the available mechanisms). Windows Azure for example also uses the same mechanism in many of its APIs. There are three challenges that any developer working for first time in Metro will have to face to consume S3, the new WinRT APIs, the asynchronous nature of them and the complexity introduced for generating the Authorization header. Having said that, I decided to write this post with some of the gotchas I found myself trying to consume this Amazon service. 1. Generating the signature for the Authorization header All the cryptography APIs in WinRT are available under Windows.Security.Cryptography namespace. Many of operations available in these APIs uses the concept of buffers (IBuffer) for representing a chunk of binary data. As you will see in the example below, these buffers are mainly generated with the use of static methods in a WinRT class CryptographicBuffer available as part of the namespace previously mentioned. private string DeriveAuthToken(string resource, string httpMethod, string timestamp) { var stringToSign = string.Format("{0}\n" + "\n" + "\n" + "\n" + "x-amz-date:{1}\n" + "/{2}/", httpMethod, timestamp, resource); var algorithm = MacAlgorithmProvider.OpenAlgorithm("HMAC_SHA1"); var keyMaterial = CryptographicBuffer.CreateFromByteArray(Encoding.UTF8.GetBytes(this.secret)); var hmacKey = algorithm.CreateKey(keyMaterial); var signature = CryptographicEngine.Sign( hmacKey, CryptographicBuffer.CreateFromByteArray(Encoding.UTF8.GetBytes(stringToSign)) ); return CryptographicBuffer.EncodeToBase64String(signature); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The algorithm that determines the information or content you need to use for generating the signature is very well described as part of the AWS documentation. In this case, this method is generating a signature required for creating a new bucket. A HmacSha1 hash is computed using a secret or symetric key provided by AWS in the management console. 2. Sending an Http Request to the S3 service WinRT also ships with the System.Net.Http.HttpClient that was first introduced some months ago with ASP.NET Web API. This client provides a rich interface on top the traditional WebHttpRequest class, and also solves some of limitations found in this last one. There are a few things that don't work with a raw WebHttpRequest such as setting the Host header, which is something absolutely required for consuming S3. Also, HttpClient is more friendly for doing unit tests, as it receives a HttpMessageHandler as part of the constructor that can fake to emulate a real http call. This is how the code for consuming the service with HttpClient looks like, public async Task<S3Response> CreateBucket(string name, string region = null, params string[] acl) { var timestamp = string.Format("{0:r}", DateTime.UtcNow); var auth = DeriveAuthToken(name, "PUT", timestamp); var request = new HttpRequestMessage(HttpMethod.Put, "http://s3.amazonaws.com/"); request.Headers.Host = string.Format("{0}.s3.amazonaws.com", name); request.Headers.TryAddWithoutValidation("Authorization", "AWS " + this.key + ":" + auth); request.Headers.Add("x-amz-date", timestamp); var client = new HttpClient(); var response = await client.SendAsync(request); return new S3Response { Succeed = response.StatusCode == HttpStatusCode.OK, Message = (response.Content != null) ? await response.Content.ReadAsStringAsync() : null }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You will notice a few additional things in this code. By default, HttpClient validates the values for some well-know headers, and Authorization is one of them. It won't allow you to set a value with ":" on it, which is something that S3 expects. However, that's not a problem at all, as you can skip the validation by using the TryAddWithoutValidation method. Also, the code is heavily relying on the new async and await keywords to transform all the asynchronous calls into synchronous ones. In case you would want to unit test this code and faking the call to the real S3 service, you should have to modify it to inject a custom HttpMessageHandler into the HttpClient. The following implementation illustrates this concept, In case you would want to unit test this code and faking the call to the real S3 service, you should have to modify it to inject a custom HttpMessageHandler into the HttpClient. The following implementation illustrates this concept, public class FakeHttpMessageHandler : HttpMessageHandler { HttpResponseMessage response; public FakeHttpMessageHandler(HttpResponseMessage response) { this.response = response; } protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) { var tcs = new TaskCompletionSource<HttpResponseMessage>(); tcs.SetResult(response); return tcs.Task; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You can use this handler for injecting any response while you are unit testing the code.

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  • Consuming the Amazon S3 service from a Win8 Metro Application

    - by cibrax
    As many of the existing Http APIs for Cloud Services, AWS also provides a set of different platform SDKs for hiding many of complexities present in the APIs. While there is a platform SDK for .NET, which is open source and available in C#, that SDK does not work in Win8 Metro Applications for the changes introduced in WinRT. WinRT offers a complete different set of APIs for doing I/O operations such as doing http calls or using cryptography for signing or encrypting data, two aspects that are absolutely necessary for consuming AWS. All the I/O APIs available as part of WinRT are asynchronous, and uses the TPL model for .NET applications (HTML and JavaScript Metro applications use a model based in promises, which is similar concept).  In the case of S3, the http Authorization header is used for two purposes, authenticating clients and make sure the messages were not altered while they were in transit. For doing that, it uses a signature or hash of the message content and some of the headers using a symmetric key (That's just one of the available mechanisms). Windows Azure for example also uses the same mechanism in many of its APIs. There are three challenges that any developer working for first time in Metro will have to face to consume S3, the new WinRT APIs, the asynchronous nature of them and the complexity introduced for generating the Authorization header. Having said that, I decided to write this post with some of the gotchas I found myself trying to consume this Amazon service. 1. Generating the signature for the Authorization header All the cryptography APIs in WinRT are available under Windows.Security.Cryptography namespace. Many of operations available in these APIs uses the concept of buffers (IBuffer) for representing a chunk of binary data. As you will see in the example below, these buffers are mainly generated with the use of static methods in a WinRT class CryptographicBuffer available as part of the namespace previously mentioned. private string DeriveAuthToken(string resource, string httpMethod, string timestamp) { var stringToSign = string.Format("{0}\n" + "\n" + "\n" + "\n" + "x-amz-date:{1}\n" + "/{2}/", httpMethod, timestamp, resource); var algorithm = MacAlgorithmProvider.OpenAlgorithm("HMAC_SHA1"); var keyMaterial = CryptographicBuffer.CreateFromByteArray(Encoding.UTF8.GetBytes(this.secret)); var hmacKey = algorithm.CreateKey(keyMaterial); var signature = CryptographicEngine.Sign( hmacKey, CryptographicBuffer.CreateFromByteArray(Encoding.UTF8.GetBytes(stringToSign)) ); return CryptographicBuffer.EncodeToBase64String(signature); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The algorithm that determines the information or content you need to use for generating the signature is very well described as part of the AWS documentation. In this case, this method is generating a signature required for creating a new bucket. A HmacSha1 hash is computed using a secret or symetric key provided by AWS in the management console. 2. Sending an Http Request to the S3 service WinRT also ships with the System.Net.Http.HttpClient that was first introduced some months ago with ASP.NET Web API. This client provides a rich interface on top the traditional WebHttpRequest class, and also solves some of limitations found in this last one. There are a few things that don't work with a raw WebHttpRequest such as setting the Host header, which is something absolutely required for consuming S3. Also, HttpClient is more friendly for doing unit tests, as it receives a HttpMessageHandler as part of the constructor that can fake to emulate a real http call. This is how the code for consuming the service with HttpClient looks like, public async Task<S3Response> CreateBucket(string name, string region = null, params string[] acl) { var timestamp = string.Format("{0:r}", DateTime.UtcNow); var auth = DeriveAuthToken(name, "PUT", timestamp); var request = new HttpRequestMessage(HttpMethod.Put, "http://s3.amazonaws.com/"); request.Headers.Host = string.Format("{0}.s3.amazonaws.com", name); request.Headers.TryAddWithoutValidation("Authorization", "AWS " + this.key + ":" + auth); request.Headers.Add("x-amz-date", timestamp); var client = new HttpClient(); var response = await client.SendAsync(request); return new S3Response { Succeed = response.StatusCode == HttpStatusCode.OK, Message = (response.Content != null) ? await response.Content.ReadAsStringAsync() : null }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You will notice a few additional things in this code. By default, HttpClient validates the values for some well-know headers, and Authorization is one of them. It won't allow you to set a value with ":" on it, which is something that S3 expects. However, that's not a problem at all, as you can skip the validation by using the TryAddWithoutValidation method. Also, the code is heavily relying on the new async and await keywords to transform all the asynchronous calls into synchronous ones. In case you would want to unit test this code and faking the call to the real S3 service, you should have to modify it to inject a custom HttpMessageHandler into the HttpClient. The following implementation illustrates this concept, In case you would want to unit test this code and faking the call to the real S3 service, you should have to modify it to inject a custom HttpMessageHandler into the HttpClient. The following implementation illustrates this concept, public class FakeHttpMessageHandler : HttpMessageHandler { HttpResponseMessage response; public FakeHttpMessageHandler(HttpResponseMessage response) { this.response = response; } protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) { var tcs = new TaskCompletionSource<HttpResponseMessage>(); tcs.SetResult(response); return tcs.Task; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You can use this handler for injecting any response while you are unit testing the code.

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  • Certification Notes: 70-583 Designing and Developing Windows Azure Applications

    - by BuckWoody
    It’s time for another certification, and we’ve just release the 70-583 exam on Windows Azure. I’ve blogged my “study plans” here before on other certifications, so I thought I would do the same for this one. I’ll also need to take exam 70-513 and 70-516; but I’ll post my notes on those separately. None of these are “brain dumps” or any questions from the actual tests - just the books, links and notes I have from my studies. I’ll update these references as I’m studying, so bookmark this site and watch my Twitter and Facebook posts for when I’ll update them, or just subscribe to the RSS feed. A “Green” color on the check-block means I’ve done that part so far, red means I haven’t. First, I need to refresh my memory on some basic coding, so along with the Azure-specific information I’m reading the following general programming books: Introducing Microsoft .NET (Pro-Developer): http://www.amazon.com/Introducing-Microsoft-Pro-Developer-David-Platt/dp/0735619182/ref=sr_1_1?s=books&ie=UTF8&qid=1296339237&sr=1-1 Head First C#, 2E: A Learner's Guide to Real-World Programming with Visual C# and .NET: http://www.amazon.com/Head-First-2E-Real-World-Programming/dp/1449380344/ref=sr_1_1?ie=UTF8&qid=1296339176&sr=8-1 Microsoft Visual C# 2008 Step by Step : http://www.amazon.com/Microsoft-Visual-2008-Step/dp/0735624305/ref=sr_1_1?s=books&ie=UTF8&qid=1296339208&sr=1-1 c The first place to start is at the official site for the certification. That’s here: http://www.microsoft.com/learning/en/us/Exam.aspx?ID=70-583&Locale=en-us c On that page you’ll find several resources, and the first you should follow is the “Save to my learning” so you have a place to track everything. Then click the “Related Learning Plans” link and follow the videos and read the documentation in each of those bullets. There are six areas on the learning plan that you should focus on - make sure you open the learning plan to drill into the specifics. c Designing Data Storage Architecture (18%) Books I’m Reading: Links: My Notes: c Optimizing Data Access and Messaging (17%) Books I’m Reading: Links: My Notes: c Designing the Application Architecture (19%) Books I’m Reading: Links: My Notes: c Preparing for Application and Service Deployment (15%) Books I’m Reading: Links: My Notes: c Investigating and Analyzing Applications (16%) Books I’m Reading: Links: My Notes: c Designing Integrated Solutions (15%) Books I’m Reading: Links: My Notes:

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