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  • A leader election algorithm for an oriented hypercube

    - by mick
    I'm stuck with some problem where I have to design a leader election algorithm for an oriented hypercube. This should be done by using a tournament with a number of rounds equal to the dimension D of the hypercube. In each stage d, with 1 <= d < D two candidate leaders of neighbouring d-dimensional hypercubes should compete to become the single candidate leader of the (d+1)-dimensional hypercube that is the union of their respective hypercubes.

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  • Searching for cluster computation framework

    - by petkov_d
    I have a library, written in C#, containing one method: Response CalculateSomething(Request); The execution time of this method is relatively large, and there are a lot of responses that should be processed. I want to use a "cluster", spread this DLL to different machines (nodes) in this "cluster" and write some controller that will distribute responses to the nodes. There should be mechanism that perevent losing task because of node crush, load balancing. Can someone suggest framework that addresses this issue? P.S. There is a framework Qizmt written in C# but I think MapReduce is not good for the above scenario

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  • Your thoughts on Best Practices for Scientific Computing?

    - by John Smith
    A recent paper by Wilson et al (2014) pointed out 24 Best Practices for scientific programming. It's worth to have a look. I would like to hear opinions about these points from experienced programmers in scientific data analysis. Do you think these advices are helpful and practical? Or are they good only in an ideal world? Wilson G, Aruliah DA, Brown CT, Chue Hong NP, Davis M, Guy RT, Haddock SHD, Huff KD, Mitchell IM, Plumbley MD, Waugh B, White EP, Wilson P (2014) Best Practices for Scientific Computing. PLoS Biol 12:e1001745. http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001745 Box 1. Summary of Best Practices Write programs for people, not computers. (a) A program should not require its readers to hold more than a handful of facts in memory at once. (b) Make names consistent, distinctive, and meaningful. (c) Make code style and formatting consistent. Let the computer do the work. (a) Make the computer repeat tasks. (b) Save recent commands in a file for re-use. (c) Use a build tool to automate workflows. Make incremental changes. (a) Work in small steps with frequent feedback and course correction. (b) Use a version control system. (c) Put everything that has been created manually in version control. Don’t repeat yourself (or others). (a) Every piece of data must have a single authoritative representation in the system. (b) Modularize code rather than copying and pasting. (c) Re-use code instead of rewriting it. Plan for mistakes. (a) Add assertions to programs to check their operation. (b) Use an off-the-shelf unit testing library. (c) Turn bugs into test cases. (d) Use a symbolic debugger. Optimize software only after it works correctly. (a) Use a profiler to identify bottlenecks. (b) Write code in the highest-level language possible. Document design and purpose, not mechanics. (a) Document interfaces and reasons, not implementations. (b) Refactor code in preference to explaining how it works. (c) Embed the documentation for a piece of software in that software. Collaborate. (a) Use pre-merge code reviews. (b) Use pair programming when bringing someone new up to speed and when tackling particularly tricky problems. (c) Use an issue tracking tool. I'm relatively new to serious programming for scientific data analysis. When I tried to write code for pilot analyses of some of my data last year, I encountered tremendous amount of bugs both in my code and data. Bugs and errors had been around me all the time, but this time it was somewhat overwhelming. I managed to crunch the numbers at last, but I thought I couldn't put up with this mess any longer. Some actions must be taken. Without a sophisticated guide like the article above, I started to adopt "defensive style" of programming since then. A book titled "The Art of Readable Code" helped me a lot. I deployed meticulous input validations or assertions for every function, renamed a lot of variables and functions for better readability, and extracted many subroutines as reusable functions. Recently, I introduced Git and SourceTree for version control. At the moment, because my co-workers are much more reluctant about these issues, the collaboration practices (8a,b,c) have not been introduced. Actually, as the authors admitted, because all of these practices take some amount of time and effort to introduce, it may be generally hard to persuade your reluctant collaborators to comply them. I think I'm asking your opinions because I still suffer from many bugs despite all my effort on many of these practices. Bug fix may be, or should be, faster than before, but I couldn't really measure the improvement. Moreover, much of my time has been invested on defence, meaning that I haven't actually done much data analysis (offence) these days. Where is the point I should stop at in terms of productivity? I've already deployed: 1a,b,c, 2a, 3a,b,c, 4b,c, 5a,d, 6a,b, 7a,7b I'm about to have a go at: 5b,c Not yet: 2b,c, 4a, 7c, 8a,b,c (I could not really see the advantage of using GNU make (2c) for my purpose. Could anyone tell me how it helps my work with MATLAB?)

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  • Building a Distributed Commerce Infrastructure in the Cloud using Azure and Commerce Server

    - by Lewis Benge
    One of the biggest questions I routinely get asked is how scalable Commerce Server is. Of course the text book answer is the product has been around for 10 years, powers some of the largest e-Commerce websites in the world, so it scales horizontally extremely well. One argument however though is what if you can't predict the growth of demand required of your Commerce Platform, or need the ability to scale up during busy seasons such as Christmas for a retail environment but are hesitant on maintaining the infrastructure on a year-round basis? The obvious answer is to utilise the many elasticated cloud infrastructure providers that are establishing themselves in the ever-growing market, the problem however is Commerce Server is still product which has a legacy tightly coupled dependency on Windows and IIS components. Commerce Server 2009 codename "R2" however introduced to the concept of an n-tier deployment of Microsoft Commerce Server, meaning you are no longer tied to core objects API but instead have serializable Commerce Entity objects, and business logic allowing for Commerce Server to now be built into a WCF-based SOA architecture. Presentation layers no-longer now need to remain on the same physical machine as the application server, meaning you can now build the user experience into multiple-technologies and host them in multiple places – leveraging the transport benefits that a WCF service may bring, such as message queuing, security, and multiple end-points. All of this logic will still need to remain in your internal infrastructure, for two reasons. Firstly cloud based computing infrastructure does not support PCI security requirements, and secondly even though many of the legacy Commerce Server dependencies have been abstracted away within this version of the application, it is still not a fully supported to be deployed exclusively into the cloud. If you do wish to benefit from the scalability of the cloud however, you can still achieve a great Commerce Server and Azure setup by utilising both the Azure App Fabric in terms of the service bus, and authentication services and Windows Azure to host any online presence you may require. The architecture would be something similar to this: This setup would allow you to construct your Commerce Services as part of your on-site infrastructure. These services would contain all of the channels custom business logic, and provide the overall interface back into the underlying Commerce Server components. It would be recommended that services are constructed around the specific business domain of the application, which based on your business model would usually consist of separate services around Catalogue, Orders, Search, Profiles, and Marketing. The App Fabric service bus is then used to abstract and aggregate further the services, making them available to the cloud and subsequently secured by App Fabrics authentication services. These services are now available for consumption by any client, using any supported technology – not just .NET. Thus meaning you are now able to construct apps for IPhone, integrate with Java based POS Devices, and any many other potential uses. This aggregation is useful, and forms the basis of the further strategy around diversifying and enhancing the e-Commerce experience, but also provides the foundation for the scalability we want to gain from utilising a cloud-based application platform. The Windows Azure application platform is Microsoft solution to benefiting from the true economies of scale in terms of the elasticity of the cloud. Just before the launch of the Azure Platform – Domino's pizza actually managed to run their whole SuperBowl operation from the scalability of Windows Azure, and simply switching back to their traditional operation the next day with no residual infrastructure costs. The platform also natively can subscribe to services and messages exposed within the AppFabric service bus, making it an ideal solution to build and deploy a presentation layer which will need to support of scalable infrastructure – such as a high demand public facing e-Commerce portal, or a promotion element of a brand. Windows Azure has excellent support for ASP.NET, including its own caching providers meaning expensive operations such as catalogue queries can persist in memory on the application server, reducing the demand on internal infrastructure and prioritising it for more business critical operations such as receiving orders and processing payments. Windows Azure also supports other languages too, meaning utilising this approach you can technically build a Commerce Server presentation layer in Java, PHP, or Ruby – or equally in ASP.NET or Silverlight without having to change any of the underlying business or Commerce Server implementation. This SOA-style architecture is one of the primary differentiators for Commerce Server as a product in the e-Commerce market, and now with the introduction of a WCF capability in Commerce Server 2009/2009 R2 the opportunities for extensibility of the both the user experience, and integration into third parties, are drastically increased, all with no effect to the underlying channel logic. So if you are looking at deployment options for your e-Commerce application to help support demand in a cost effective way. I would highly recommend you consider looking at Windows Azure, and if you have any questions in-particular about this style of deployment, please feel free to get in touch!

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  • Odd company release cycle: Go Distributed Source Control?

    - by MrLane
    sorry about this long post, but I think it is worth it! I have just started with a small .NET shop that operates quite a bit differently to other places that I have worked. Unlike any of my previous positions, the software written here is targetted at multiple customers and not every customer gets the latest release of the software at the same time. As such, there is no "current production version." When a customer does get an update, they also get all of the features added to he software since their last update, which could be a long time ago. The software is highly configurable and features can be turned on and off: so called "feature toggles." Release cycles are very tight here, in fact they are not on a shedule: when a feature is complete the software is deployed to the relevant customer. The team only last year moved from Visual Source Safe to Team Foundation Server. The problem is they still use TFS as if it were VSS and enforce Checkout locks on a single code branch. Whenever a bug fix gets put out into the field (even for a single customer) they simply build whatever is in TFS, test the bug was fixed and deploy to the customer! (Myself coming from a pharma and medical devices software background this is unbeliveable!). The result is that half baked dev code gets put into production without being even tested. Bugs are always slipping into release builds, but often a customer who just got a build will not see these bugs if they don't use the feature the bug is in. The director knows this is a problem as the company is starting to grow all of a sudden with some big clients coming on board and more smaller ones. I have been asked to look at source control options in order to eliminate deploying of buggy or unfinished code but to not sacrifice the somewhat asyncronous nature of the teams releases. I have used VSS, TFS, SVN and Bazaar in my career, but TFS is where most of my experience has been. Previously most teams I have worked with use a two or three branch solution of Dev-Test-Prod, where for a month developers work directly in Dev and then changes are merged to Test then Prod, or promoted "when its done" rather than on a fixed cycle. Automated builds were used, using either Cruise Control or Team Build. In my previous job Bazaar was used sitting on top of SVN: devs worked in their own small feature branches then pushed their changes to SVN (which was tied into TeamCity). This was nice in that it was easy to isolate changes and share them with other peoples branches. With both of these models there was a central dev and prod (and sometimes test) branch through which code was pushed (and labels were used to mark builds in prod from which releases were made...and these were made into branches for bug fixes to releases and merged back to dev). This doesn't really suit the way of working here, however: there is no order to when various features will be released, they get pushed when they are complete. With this requirement the "continuous integration" approach as I see it breaks down. To get a new feature out with continuous integration it has to be pushed via dev-test-prod and that will capture any unfinished work in dev. I am thinking that to overcome this we should go down a heavily feature branched model with NO dev-test-prod branches, rather the source should exist as a series of feature branches which when development work is complete are locked, tested, fixed, locked, tested and then released. Other feature branches can grab changes from other branches when they need/want, so eventually all changes get absorbed into everyone elses. This fits very much down a pure Bazaar model from what I experienced at my last job. As flexible as this sounds it just seems odd to not have a dev trunk or prod branch somewhere, and I am worried about branches forking never to re-integrate, or small late changes made that never get pulled across to other branches and developers complaining about merge disasters... What are peoples thoughts on this? A second final question: I am somewhat confused about the exact definition of distributed source control: some people seem to suggest it is about just not having a central repository like TFS or SVN, some say it is about being disconnected (SVN is 90% disconnected and TFS has a perfectly functional offline mode) and others say it is about Feature Branching and ease of merging between branches with no parent-child relationship (TFS also has baseless merging!). Perhaps this is a second question!

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  • Any Open Source Pregel like framework for distributed processing of large Graphs?

    - by Akshay Bhat
    Google has described a novel framework for distributed processing on Massive Graphs. http://portal.acm.org/citation.cfm?id=1582716.1582723 I wanted to know if similar to Hadoop (Map-Reduce) are there any open source implementations of this framework? I am actually in process of writing a Pseudo distributed one using python and multiprocessing module and thus wanted to know if someone else has also tried implementing it. Since public information about this framework is extremely scarce. (A link above and a blog post at Google Research)

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  • Cloud computing over Client-server: differences, cons and pros ?

    - by Vimvq1987
    As far as I know, Cloud computing might be a evolution in software architect, and it will replace some current architectures, such as client-server. These two architecture seem to share similarities for me (I know very little about both), but I don't know the differences between them. What are the cons and pros of cloud computing over client-server architecture? Thank you so much.

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  • What Parallel computing APIs take good use of sockets?

    - by Ole Jak
    What Parallel computing APIs take good use of sockets? So my programm uses soskets, what Parallel computing APIs I can use that would help me but will not obligate me to go from sockets to anything else... I mean when we are on claster with some special, not socket infrastructure sistem that API emulates something like socket but uses that infrustructure (so programm peforms much faster then on sockets, but keeps having nice soskets API)

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  • Azure Grid Computing - Worker Roles as HPC Compute Nodes

    - by JoshReuben
    Overview ·        With HPC 2008 R2 SP1 You can add Azure worker roles as compute nodes in a local Windows HPC Server cluster. ·        The subscription for Windows Azure like any other Azure Service - charged for the time that the role instances are available, as well as for the compute and storage services that are used on the nodes. ·        Win-Win ? - Azure charges the computer hour cost (according to vm size) amortized over a month – so you save on purchasing compute node hardware. Microsoft wins because you need to purchase HPC to have a local head node for managing this compute cluster grid distributed in the cloud. ·        Blob storage is used to hold input & output files of each job. I can see how Parametric Sweep HPC jobs can be supported (where the same job is run multiple times on each node against different input units), but not MPI.NET (where different HPC Job instances function as coordinated agents and conduct master-slave inter-process communication), unless Azure is somehow tunneling MPI communication through inter-WorkerRole Azure Queues. ·        this is not the end of the story for Azure Grid Computing. If MS requires you to purchase a local HPC license (and administrate it), what's to stop a 3rd party from doing this and encapsulating exposing HPC WCF Broker Service to you for managing compute nodes? If MS doesn’t  provide head node as a service, someone else will! Process ·        requires creation of a worker node template that specifies a connection to an existing subscription for Windows Azure + an availability policy for the worker nodes. ·        After worker nodes are added to the cluster, you can start them, which provisions the Windows Azure role instances, and then bring them online to run HPC cluster jobs. ·        A Windows Azure worker role instance runs a HPC compatible Azure guest operating system which runs on the VMs that host your service. The guest operating system is updated monthly. You can choose to upgrade the guest OS for your service automatically each time an update is released - All role instances defined by your service will run on the guest operating system version that you specify. see Windows Azure Guest OS Releases and SDK Compatibility Matrix (http://go.microsoft.com/fwlink/?LinkId=190549). ·        use the hpcpack command to upload file packages and install files to run on the worker nodes. see hpcpack (http://go.microsoft.com/fwlink/?LinkID=205514). Requirements ·        assuming you have an azure subscription account and the HPC head node installed and configured. ·        Install HPC Pack 2008 R2 SP 1 -  see Microsoft HPC Pack 2008 R2 Service Pack 1 Release Notes (http://go.microsoft.com/fwlink/?LinkID=202812). ·        Configure the head node to connect to the Internet - connectivity is provided by the connection of the head node to the enterprise network. You may need to configure a proxy client on the head node. Any cluster network topology (1-5) is supported). ·        Configure the firewall - allow outbound TCP traffic on the following ports: 80,       443, 5901, 5902, 7998, 7999 ·        Note: HPC Server  uses Admin Mode (Elevated Privileges) in Windows Azure to give the service administrator of the subscription the necessary privileges to initialize HPC cluster services on the worker nodes. ·        Obtain a Windows Azure subscription certificate - the Windows Azure subscription must be configured with a public subscription (API) certificate -a valid X.509 certificate with a key size of at least 2048 bits. Generate a self-sign certificate & upload a .cer file to the Windows Azure Portal Account page > Manage my API Certificates link. see Using the Windows Azure Service Management API (http://go.microsoft.com/fwlink/?LinkId=205526). ·        import the certificate with an associated private key on the HPC cluster head node - into the trusted root store of the local computer account. Obtain Windows Azure Connection Information for HPC Server ·        required for each worker node template ·        copy from azure portal - Get from: navigation pane > Hosted Services > Storage Accounts & CDN ·        Subscription ID - a 32-char hex string in the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. In Properties pane. ·        Subscription certificate thumbprint - a 40-char hex string (you need to remove spaces). In Management Certificates > Properties pane. ·        Service name - the value of <ServiceName> configured in the public URL of the service (http://<ServiceName>.cloudapp.net). In Hosted Services > Properties pane. ·        Blob Storage account name - the value of <StorageAccountName> configured in the public URL of the account (http://<StorageAccountName>.blob.core.windows.net). In Storage Accounts > Properties pane. Import the Azure Subscription Certificate on the HPC Head Node ·        enable the services for Windows HPC Server  to authenticate properly with the Windows Azure subscription. ·        use the Certificates MMC snap-in to import the certificate to the Trusted Root Certification Authorities store of the local computer account. The certificate must be in PFX format (.pfx or .p12 file) with a private key that is protected by a password. ·        see Certificates (http://go.microsoft.com/fwlink/?LinkId=163918). ·        To open the certificates snapin: Run > mmc. File > Add/Remove Snap-in > certificates > Computer account > Local Computer ·        To import the certificate via wizard - Certificates > Trusted Root Certification Authorities > Certificates > All Tasks > Import ·        After the certificate is imported, it appears in the details pane in the Certificates snap-in. You can open the certificate to check its status. Configure a Proxy Client on the HPC Head Node ·        the following Windows HPC Server services must be able to communicate over the Internet (through the firewall) with the services for Windows Azure: HPCManagement, HPCScheduler, HPCBrokerWorker. ·        Create a Windows Azure Worker Node Template ·        Edit HPC node templates in HPC Node Template Editor. ·        Specify: 1) Windows Azure subscription connection info (unique service name) for adding a set of worker nodes to the cluster + 2)worker node availability policy – rules for deploying / removing worker role instances in Windows Azure o   HPC Cluster Manager > Configuration > Navigation Pane > Node Templates > Actions pane > New à Create Node Template Wizard or Edit à Node Template Editor o   Choose Node Template Type page - Windows Azure worker node template o   Specify Template Name page – template name & description o   Provide Connection Information page – Azure Subscription ID (text) & Subscription certificate (browse) o   Provide Service Information page - Azure service name + blob storage account name (optionally click Retrieve Connection Information to get list of available from azure – possible LRT). o   Configure Azure Availability Policy page - how Windows Azure worker nodes start / stop (online / offline the worker role instance -  add / remove) – manual / automatic o   for automatic - In the Configure Windows Azure Worker Availability Policy dialog -select days and hours for worker nodes to start / stop. ·        To validate the Windows Azure connection information, on the template's Connection Information tab > Validate connection information. ·        You can upload a file package to the storage account that is specified in the template - eg upload application or service files that will run on the worker nodes. see hpcpack (http://go.microsoft.com/fwlink/?LinkID=205514). Add Azure Worker Nodes to the HPC Cluster ·        Use the Add Node Wizard – specify: 1) the worker node template, 2) The number of worker nodes   (within the quota of role instances in the azure subscription), and 3)           The VM size of the worker nodes : ExtraSmall, Small, Medium, Large, or ExtraLarge.  ·        to add worker nodes of different sizes, must run the Add Node Wizard separately for each size. ·        All worker nodes that are added to the cluster by using a specific worker node template define a set of worker nodes that will be deployed and managed together in Windows Azure when you start the nodes. This includes worker nodes that you add later by using the worker node template and, if you choose, worker nodes of different sizes. You cannot start, stop, or delete individual worker nodes. ·        To add Windows Azure worker nodes o   In HPC Cluster Manager: Node Management > Actions pane > Add Node à Add Node Wizard o   Select Deployment Method page - Add Azure Worker nodes o   Specify New Nodes page - select a worker node template, specify the number and size of the worker nodes ·        After you add worker nodes to the cluster, they are in the Not-Deployed state, and they have a health state of Unapproved. Before you can use the worker nodes to run jobs, you must start them and then bring them online. ·        Worker nodes are numbered consecutively in a naming series that begins with the root name AzureCN – this is non-configurable. Deploying Windows Azure Worker Nodes ·        To deploy the role instances in Windows Azure - start the worker nodes added to the HPC cluster and bring the nodes online so that they are available to run cluster jobs. This can be configured in the HPC Azure Worker Node Template – Azure Availability Policy -  to be automatic or manual. ·        The Start, Stop, and Delete actions take place on the set of worker nodes that are configured by a specific worker node template. You cannot perform one of these actions on a single worker node in a set. You also cannot perform a single action on two sets of worker nodes (specified by two different worker node templates). ·        ·          Starting a set of worker nodes deploys a set of worker role instances in Windows Azure, which can take some time to complete, depending on the number of worker nodes and the performance of Windows Azure. ·        To start worker nodes manually and bring them online o   In HPC Node Management > Navigation Pane > Nodes > List / Heat Map view - select one or more worker nodes. o   Actions pane > Start – in the Start Azure Worker Nodes dialog, select a node template. o   the state of the worker nodes changes from Not Deployed to track the provisioning progress – worker node Details Pane > Provisioning Log tab. o   If there were errors during the provisioning of one or more worker nodes, the state of those nodes is set to Unknown and the node health is set to Unapproved. To determine the reason for the failure, review the provisioning logs for the nodes. o   After a worker node starts successfully, the node state changes to Offline. To bring the nodes online, select the nodes that are in the Offline state > Bring Online. ·        Troubleshooting o   check node template. o   use telnet to test connectivity: telnet <ServiceName>.cloudapp.net 7999 o   check node status - Deployment status information appears in the service account information in the Windows Azure Portal - HPC queries this -  see  node status information for any failed nodes in HPC Node Management. ·        When role instances are deployed, file packages that were previously uploaded to the storage account using the hpcpack command are automatically installed. You can also upload file packages to storage after the worker nodes are started, and then manually install them on the worker nodes. see hpcpack (http://go.microsoft.com/fwlink/?LinkID=205514). ·        to remove a set of role instances in Windows Azure - stop the nodes by using HPC Cluster Manager (apply the Stop action). This deletes the role instances from the service and changes the state of the worker nodes in the HPC cluster to Not Deployed. ·        Each time that you start a set of worker nodes, two proxy role instances (size Small) are configured in Windows Azure to facilitate communication between HPC Cluster Manager and the worker nodes. The proxy role instances are not listed in HPC Cluster Manager after the worker nodes are added. However, the instances appear in the Windows Azure Portal. The proxy role instances incur charges in Windows Azure along with the worker node instances, and they count toward the quota of role instances in the subscription.

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  • The Proper Use of the VM Role in Windows Azure

    - by BuckWoody
    At the Professional Developer’s Conference (PDC) in 2010 we announced an addition to the Computational Roles in Windows Azure, called the VM Role. This new feature allows a great deal of control over the applications you write, but some have confused it with our full infrastructure offering in Windows Hyper-V. There is a proper architecture pattern for both of them. Virtualization Virtualization is the process of taking all of the hardware of a physical computer and replicating it in software alone. This means that a single computer can “host” or run several “virtual” computers. These virtual computers can run anywhere - including at a vendor’s location. Some companies refer to this as Cloud Computing since the hardware is operated and maintained elsewhere. IaaS The more detailed definition of this type of computing is called Infrastructure as a Service (Iaas) since it removes the need for you to maintain hardware at your organization. The operating system, drivers, and all the other software required to run an application are still under your control and your responsibility to license, patch, and scale. Microsoft has an offering in this space called Hyper-V, that runs on the Windows operating system. Combined with a hardware hosting vendor and the System Center software to create and deploy Virtual Machines (a process referred to as provisioning), you can create a Cloud environment with full control over all aspects of the machine, including multiple operating systems if you like. Hosting machines and provisioning them at your own buildings is sometimes called a Private Cloud, and hosting them somewhere else is often called a Public Cloud. State-ful and Stateless Programming This paradigm does not create a new, scalable way of computing. It simply moves the hardware away. The reason is that when you limit the Cloud efforts to a Virtual Machine, you are in effect limiting the computing resources to what that single system can provide. This is because much of the software developed in this environment maintains “state” - and that requires a little explanation. “State-ful programming” means that all parts of the computing environment stay connected to each other throughout a compute cycle. The system expects the memory, CPU, storage and network to remain in the same state from the beginning of the process to the end. You can think of this as a telephone conversation - you expect that the other person picks up the phone, listens to you, and talks back all in a single unit of time. In “Stateless” computing the system is designed to allow the different parts of the code to run independently of each other. You can think of this like an e-mail exchange. You compose an e-mail from your system (it has the state when you’re doing that) and then you walk away for a bit to make some coffee. A few minutes later you click the “send” button (the network has the state) and you go to a meeting. The server receives the message and stores it on a mail program’s database (the mail server has the state now) and continues working on other mail. Finally, the other party logs on to their mail client and reads the mail (the other user has the state) and responds to it and so on. These events might be separated by milliseconds or even days, but the system continues to operate. The entire process doesn’t maintain the state, each component does. This is the exact concept behind coding for Windows Azure. The stateless programming model allows amazing rates of scale, since the message (think of the e-mail) can be broken apart by multiple programs and worked on in parallel (like when the e-mail goes to hundreds of users), and only the order of re-assembling the work is important to consider. For the exact same reason, if the system makes copies of those running programs as Windows Azure does, you have built-in redundancy and recovery. It’s just built into the design. The Difference Between Infrastructure Designs and Platform Designs When you simply take a physical server running software and virtualize it either privately or publicly, you haven’t done anything to allow the code to scale or have recovery. That all has to be handled by adding more code and more Virtual Machines that have a slight lag in maintaining the running state of the system. Add more machines and you get more lag, so the scale is limited. This is the primary limitation with IaaS. It’s also not as easy to deploy these VM’s, and more importantly, you’re often charged on a longer basis to remove them. your agility in IaaS is more limited. Windows Azure is a Platform - meaning that you get objects you can code against. The code you write runs on multiple nodes with multiple copies, and it all works because of the magic of Stateless programming. you don’t worry, or even care, about what is running underneath. It could be Windows (and it is in fact a type of Windows Server), Linux, or anything else - but that' isn’t what you want to manage, monitor, maintain or license. You don’t want to deploy an operating system - you want to deploy an application. You want your code to run, and you don’t care how it does that. Another benefit to PaaS is that you can ask for hundreds or thousands of new nodes of computing power - there’s no provisioning, it just happens. And you can stop using them quicker - and the base code for your application does not have to change to make this happen. Windows Azure Roles and Their Use If you need your code to have a user interface, in Visual Studio you add a Web Role to your project, and if the code needs to do work that doesn’t involve a user interface you can add a Worker Role. They are just containers that act a certain way. I’ll provide more detail on those later. Note: That’s a general description, so it’s not entirely accurate, but it’s accurate enough for this discussion. So now we’re back to that VM Role. Because of the name, some have mistakenly thought that you can take a Virtual Machine running, say Linux, and deploy it to Windows Azure using this Role. But you can’t. That’s not what it is designed for at all. If you do need that kind of deployment, you should look into Hyper-V and System Center to create the Private or Public Infrastructure as a Service. What the VM Role is actually designed to do is to allow you to have a great deal of control over the system where your code will run. Let’s take an example. You’ve heard about Windows Azure, and Platform programming. You’re convinced it’s the right way to code. But you have a lot of things you’ve written in another way at your company. Re-writing all of your code to take advantage of Windows Azure will take a long time. Or perhaps you have a certain version of Apache Web Server that you need for your code to work. In both cases, you think you can (or already have) code the the software to be “Stateless”, you just need more control over the place where the code runs. That’s the place where a VM Role makes sense. Recap Virtualizing servers alone has limitations of scale, availability and recovery. Microsoft’s offering in this area is Hyper-V and System Center, not the VM Role. The VM Role is still used for running Stateless code, just like the Web and Worker Roles, with the exception that it allows you more control over the environment of where that code runs.

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  • Bytes by MSDN - Let's talk Cloud

    - by Wallym
    While I was at DevConnections in Las Vegas, I was honored to be interviewed by Tim Huckaby for "Bytes by MSDN" on Cloud Computing. Here's a short intro from the talk:Do you believe in the Cloud? Wallace McClure, Founder and Architect of Scalable Development, Inc., does. His customers are extremely interested in the value and economies of scale that Cloud Computing, and more specifically, Windows Azure can bring. Building out an infrastructure that supports your web service or application can be expensive, complicated and time consuming. Or you could look to the Microsoft cloud. The Windows Azure platform is a flexible cloud–computing platform that lets you focus on solving business problems and addressing customer needs. Wally talks about all this, and more, in this interview with Tim Huckaby, and in his Windows Azure podcasts.

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  • Azure, a Beautiful Color, and So Much More...

    - by KKline
    Windows and SQL Azure Resources Cloud computing is more than just the latest buzz word in the IT trade papers. It is a remarkable paradigm shift with as much potential to "turn over the apple cart" of IT computing as client-server had for the world of mainframe and minicomputers. If you're not spending time to learn about cloud computing, in general, and SQL Azure, in particular, then you're missing the boat in a big way. (Ha! Two big metaphors in one afternoon. My high-school English teacher would...(read more)

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  • cloud/grid computing

    - by tom smith
    Hi guys. I'm appologizing in advance to the guys who will tell me this isn't a tech/server/IT issue! But I've been beating my head around this for a couple of days now. I'm trying figure out who to talk to, or which company I can approach to try to see if there are Grid/Cloud Computing companies who have programs setup to deal with colleges. I'm dealing with a compsci course, and we're looking at a few projects that would require a great deal of computing/computational resources. But in calling different companies (HP/Rackspace/etc..) I'm either not getting through to the right depts, or to the right people, or the companies just aren't setup for this. There are plenty of companies who have discounts for desktop software/hardware, but who in the biz deals with discounts/offerings for Cloud/Grid Computing solutions?? Any thoughts/pointers would be greatly appreciated. Thanks -tom

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  • File sharing for small, distributed, non-technical, non-profit organization?

    - by mnmldave
    Problem: I've started volunteering for a small non-profit with fewer than five non-technical Windows users who need to share 20-30GB of files (Office documents, images, PDFs, etc.) amongst themselves online. Background: The users are accustomed to a Windows network share on a machine that backed up their data locally. An on-site "disaster" has forced them to work from their homes for awhile and to re-evaluate their file sharing needs (office was located in an old building with obvious electrical issues, etc.). Access to time from volunteers with IT experience seems to be difficult. Demonstrably minimizing energy consumption is a nice-to-have. I'm currently considering Jungle Disk (a Desktop account shared amongst the handful of employees since their TOS and my inquiries to their helpdesk seem to indicate this is permissible). It appears easy-to-use, inexpensive, secure, has backup functionality, and can scale to accomodate more data when needed. I've not used it myself though (have only used Dropbox for personal use) and systems isn't my area of expertise, so am worried I might be jumping on a bandwagon. That said, any suggestions, thoughts or similar experiences would be really appreciated.

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