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  • Distributed, persistent cache using EHCache

    - by Richard
    I currently have a distributed cache using EHCache via RMI that works just fine. I was wondering if you can include persistence with the caches to create a distributed, persistent cache. Alongside this, if the cache was persistent, would it load from the file store, then bootstrap from the cache cluster? Basically, what I want is: Cache starts Cache loads persistent objects from the file store Cache joins the distruted cluster and bootstraps as normal The usecase behind this is having 2 identical components running on independent machines, distributing the cache to avoid losing data in the event that one of the components fails. The persistence would guard against losing all data on the rare occasion that both components fail. Would moving to another distribution method (such as Terracotta) support this?

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  • Why isn't SSL/TLS built into modern Operating Systems?

    - by Channel72
    A lot of the basic network protocols that make up the infrastructure of the Internet are built in to most major Operating Systems. Things like TCP, UDP, and DNS are all built into Linux, UNIX and Windows, and are made available to the programmer through low-level system APIs. But when it comes to SSL or TLS, one has to turn to a third-party library such as OpenSSL or Mozilla NSS. SSL is a relatively old protocol, and it's basically an industry standard as ubiquitous as TCP/IP, so why isn't it built into most Operating Systems?

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  • What route to take to become a systems developer?

    - by Ramin
    In the past I have done a lot of Java and Python coding. Mostly, I worked on web apps and some simple console or gui apps. I also have a formal education in computer science. What route should I take to become a systems developer? I always did like C++, but never had a chance to use it for anything. Would mastering C++ be one of the steps? If so what resources can you suggest? Also, I would like to know how much different is the work between plain old development and systems development. There seem to be a lot of overlapping between the two.

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  • Choice of operating systems for a Rackspace cloud installation

    - by riteshmnayak
    I am planning to use Rackspace cloud services to host a java web application and also run apace for wordpress and trac. What would be a stable operating system to host such an application. My requirements are that the core OS bundle should be minimalistic (so I can install only what I want), consume very little memory and be performant. I would also need it to contain softwares for the common lamp stack, J2EE stack etc. A supported package manager would be lovely. My choices are listed below. RHEL 5.3 or 5.4 Debian Lenny Ubuntu 8.04 onwards Centos 5.3 or 5.4 Arch 2009.02 Gentoo 2008.0 or 10.1 Fedora 11 or 12 PS: can somebody add the rackspace tag to this? Edit to remove this line as well. Thanks

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  • Simplest distributed persistent key/value store that supports primary key range queries

    - by StaxMan
    I am looking for a properly distributed (i.e. not just sharded) and persisted (not bounded by available memory on single node, or cluster of nodes) key/value ("nosql") store that does support range queries by primary key. So far closest such system is Cassandra, which does above. However, it adds support for other features that are not essential for me. So while I like it (and will consider using it of course), I am trying to figure out if there might be other mature projects that implement what I need. Specifically, for me the only aspect of value I need is to access it as a blob. For key, however, I need range queries (as in, access values ordered, limited by start and/or end values). While values can have structures, there is no need to use that structure for anything on server side (can do client-side data binding, flexible value/content types etc). For added bonus, Cassandra style storage (journaled, all sequential writes) seems quite optimal for my use case. To help filter out answers, I have investigated some alternatives within general domain like: Voldemort (key/value, but no ordering) and CouchDB (just sharded, more batch-oriented); and am aware of systems that are not quite distributed while otherwise qualifying (bdb variants, tokyo cabinet itself (not sure if Tyrant might qualify), redis (in-memory store only)).

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  • Framework or tool for "distributed unit testing"?

    - by user262646
    Is there any tool or framework able to make it easier to test distributed software written in Java? My system under test is a peer-to-peer software, and I'd like to perform testing using something like PNUnit, but with Java instead of .Net. The system under test is a framework I'm developing to build P2P applications. It uses JXTA as a lower subsystem, trying to hide some complexities of it. It's currently an academic project, so I'm pursuing simplicity at this moment. In my test, I want to demonstrate that a peer (running in its own process, possibly with multiple threads) can discover another one (running in another process or even another machine) and that they can exchange a few messages. I'm not using mocks nor stubs because I need to see both sides working simultaneously. I realize that some kind of coordination mechanism is needed, and PNUnit seems to be able to do that. I've bumped into some initiatives like Pisces, which "aims to provide a distributed testing environment that extends JUnit, giving the developer/tester an ability to run remote JUnits and create complex test suites that are composed of several remote JUnit tests running in parallel or serially", but this project and a few others I have found seem to be long dead.

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  • Reliable test for MSDTC promoting transactions to distributed?

    - by Oded
    How can I reliably check that MSDTC has promoted a transaction to a distributed transaction, from .net code? Currently a co-worker is testing this by shutting down the coordinator on his machine - if an exception is thrown this is taken as evidence that an attempt to promote the transaction has occurred. Is this a valid test?

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  • technologies beside scaling web applications in a distributed nature

    - by wik
    Hello, I am interested in theory to scale web applications in a distributed nature, i.e. when there is some platform/stack can be extended by others applications running on different servers, etc. I am researching this field and feels the lack of the right keywords :) Interesting concepts found so far: opensocial through API, like shopify does (shopify it's a hosted ecommerce solution) semantic web not quite sure about this one Am I on the right way or am I lost anything? :) Thanks.

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  • Unit test distributed software

    - by user262646
    Is there any tool or framework able to make it easier to "unit test" distributed software written in Java? My system under test is a peer-to-peer software, and I'd like to perform testing using something like PNUnit, but with Java instead of .Net.

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  • Why is TransactionScope using a distributed transaction when I am only using LinqToSql and Ado.Net

    - by Ian Ringrose
    We are having problems on one machine, with the error message: "MSDTC on server XXX is unavailable." The code is using a TransactionScope to wrap some LingToSql database code; there is also some raw Ado.net inside of the transaction. As only a single sql database (2005) is being accessed, why is a distributed transaction being used at all? (I don’t wish to know how to enable MSDTC, as the code needs to work on the server with their current setup)

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  • Advantages of Thread pooling in embedded systems

    - by Microkernel
    I am looking at the advantages of threadpooling design pattern in Embedded systems. I have listed few advantages, please go through them, comment and please suggest any other possible advantages that I am missing. Scalability in systems like ucos-2 where there is limit on number of threads. Increasing capability of any task when necessary like Garbage collection (say in normal systems if garbage collection is running under one task, its not possible to speed it up, but in threadpooling we can easily speed it up). Can set limit on the max system load. Please suggest if I am missing anything.

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  • Efficiently separating Read/Compute/Write steps for concurrent processing of entities in Entity/Component systems

    - by TravisG
    Setup I have an entity-component architecture where Entities can have a set of attributes (which are pure data with no behavior) and there exist systems that run the entity logic which act on that data. Essentially, in somewhat pseudo-code: Entity { id; map<id_type, Attribute> attributes; } System { update(); vector<Entity> entities; } A system that just moves along all entities at a constant rate might be MovementSystem extends System { update() { for each entity in entities position = entity.attributes["position"]; position += vec3(1,1,1); } } Essentially, I'm trying to parallelise update() as efficiently as possible. This can be done by running entire systems in parallel, or by giving each update() of one system a couple of components so different threads can execute the update of the same system, but for a different subset of entities registered with that system. Problem In reality, these systems sometimes require that entities interact(/read/write data from/to) each other, sometimes within the same system (e.g. an AI system that reads state from other entities surrounding the current processed entity), but sometimes between different systems that depend on each other (i.e. a movement system that requires data from a system that processes user input). Now, when trying to parallelize the update phases of entity/component systems, the phases in which data (components/attributes) from Entities are read and used to compute something, and the phase where the modified data is written back to entities need to be separated in order to avoid data races. Otherwise the only way (not taking into account just "critical section"ing everything) to avoid them is to serialize parts of the update process that depend on other parts. This seems ugly. To me it would seem more elegant to be able to (ideally) have all processing running in parallel, where a system may read data from all entities as it wishes, but doesn't write modifications to that data back until some later point. The fact that this is even possible is based on the assumption that modification write-backs are usually very small in complexity, and don't require much performance, whereas computations are very expensive (relatively). So the overhead added by a delayed-write phase might be evened out by more efficient updating of entities (by having threads work more % of the time instead of waiting). A concrete example of this might be a system that updates physics. The system needs to both read and write a lot of data to and from entities. Optimally, there would be a system in place where all available threads update a subset of all entities registered with the physics system. In the case of the physics system this isn't trivially possible because of race conditions. So without a workaround, we would have to find other systems to run in parallel (which don't modify the same data as the physics system), other wise the remaining threads are waiting and wasting time. However, that has disadvantages Practically, the L3 cache is pretty much always better utilized when updating a large system with multiple threads, as opposed to multiple systems at once, which all act on different sets of data. Finding and assembling other systems to run in parallel can be extremely time consuming to design well enough to optimize performance. Sometimes, it might even not be possible at all because a system just depends on data that is touched by all other systems. Solution? In my thinking, a possible solution would be a system where reading/updating and writing of data is separated, so that in one expensive phase, systems only read data and compute what they need to compute, and then in a separate, performance-wise cheap, write phase, attributes of entities that needed to be modified are finally written back to the entities. The Question How might such a system be implemented to achieve optimal performance, as well as making programmer life easier? What are the implementation details of such a system and what might have to be changed in the existing EC-architecture to accommodate this solution?

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  • Do different operating systems have different read and write speeds?

    - by Ivan
    If I have two different operating systems, such as Windows 8 and Ubuntu, running on the same hardware, will the two operating systems have different read and write speeds? My guess is that there would be minimal difference between operating systems and read and write speeds to the hard disk since the major limited factor is seeking; however, different operating systems may use different file systems in order to attempt to reduce seek time in the hard disk. Likewise, I'm sure that modern operating systems will not actually write directly to the hard disk, and instead will just have it in memory and marked with a dirty bit. Are there any studies that show differences in read and write speeds between OSs? Or would the file system being used by the OS matter more than the OS itself?

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  • EMEA Engineered Systems Partner Update Call&ndash;October 30th 2013

    - by JuergenKress
    EMEA Engineered Systems Partner Update Call: Engineered Systems (Including Exalogic) updates from Oracle OpenWorld on 30th October, 2013 at 15:00 CET (UTC/GMT +1 Hour) We are pleased to invite you to the next Webcast from our Engineered Systems Partner Update Series. This time it will be all around "Engineered Systems updates from Oracle OpenWorld – all the news from Exalogic included" on Wednesday 30th October, 2013 at 15:00 CET (UTC/GMT +1 Hour). One more year, San Francisco hosted the Oracle OpenWorld, in the month of September. Every year, thousands of partners and customers attend this event to discover new products and solutions, improve their technical proficiency and knowledge, learn tips and tricks for currently installed products and understand where the industry is headed. In case you could not make it to San Francisco this time, we want to provide you with the key updates announced at Oracle OpenWorld around Engineered Systems. Please mark your diaries. You can also attend Larry’s keynote around the Oracle Database 12c In-Memory Database and M6 Big Memory Machine and many more on the Oracle OpenWorld On Demand website. Agenda: Overview of latest Engineered Systems including Exalogic and how Oracle Fusion Middleware performs on the machine How to articulate their value to customers Webcast Joining details: To Join the webcast CLICK HERE For audio reception please use the following details: Global Dial-in Numbers Session/Conference ID: 595 534 979 Password: 12385 WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: Engineered Systems,Exalogic,OOW,Oracle OpenWorld,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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  • PHP SoapClient: Problems with Distributed WSDL File

    - by Dave
    Hello, I have a problem using a distributed WSDL File ( scheme / other definitions are declared outside the actual wsdl) with php's SoapClient. This is the Fault Message I get: SOAP-ERROR: Parsing WSDL: 'getSomeInfo' already defined. After some googling , it seems to be a bug inside php as someone else discovered exactly the same problem: http://bugs.php.net/bug.php?id=45282 Has there been any bug fix(es)? Any solution to work around this bug? PS: I think posting a code snippet is senseless, since the invocation of the SoapClient ctor using just the WSDL is the only that fails. Thank you in advance, Dave

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  • How to make distributed builds using XCode 3.2 on OS X 10.6

    - by Sorin Sbarnea
    After I upgraded using a clean install from OS X 10.5 to 10.6.2 and upgraded the XCode to 3.2.1 I wasn't able to use distributed builds feature anymore. There are several issues that I detected: In most cases Bonjour is not detecting the other computers even they are on the same switch. I added a custom 'set' where I added manually the IP addreses of each computer. Even so I still get status: "unreachable" on them.BTW, ping does work without problems. Both share my computer for shared workgroup builds (distcc) and distribute builds via shared workgroup builds options are checked.

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  • What grid distributed computing frameworks are currently favoured for trading systems

    - by Rich
    There seems to a quite a few grid computing frameworks out there, but which ones are actually being used to any great extent by the investment banks for purposes of low latency distributing calculation? I'd be interested to hear answers covering both windows,Linux and cross platform. Also, what RPC mechanisms seem to be favoured most? I've heard that for reason of low latency and speed, the calculations themselves are quite often written in C++/C as calculations running on VMs are several orders of magnitude slower than native code. Does this seem to be a common scenario in practice? e.g distributed .NET grid framework running calculations written in native c++/c?

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  • Enumerating combinations in a distributed manner

    - by Reyzooti
    I have a problem where I must analyse 500C5 combinations (255244687600) of something. Distributing it over a 10 node cluster where each cluster processes roughly 10^6 combinations per second means the job will be complete in about 7hours. The problem I have is distributing the 255244687600 combinations over the 10 nodes. I'd like to present each node with 25524468760, however the algorithms I'm using can only produce the combinations sequentially, I'd like to be able to pass the set of elements and a range of combination indicies eg: [0-10^7) or [10^7,2.0 10^7) etc and have the nodes themselves figure out the combinations. The algorithms I'm using at the moment are from the following: http://home.roadrunner.com/~hinnant/combinations.html A logical question I've considered using a master node, that enumerates each of the combinations and sends work to each of the nodes, however the overhead incurred in iterating the combinations from a single node and communicating back and forth work is enormous, and will subsequently lead to the master node becoming the bottleneck. Are there any good combination iterating algorithms geared up for efficient/optimal distributed enumeration?

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  • Distributed development systems

    - by Nathan Adams
    I am interested in a system that allows for distributed development with an authentication piece. What do I mean by that? Ok so lets take SVN, SVN keeps track of revisions and doesn't care who submits, as long as you have the right to submit you can submit, really, to any part in the repository. Where does my system come into play? Being able to granulate access control and give a stackoverflow like feel to the environment. In the system I am describing we have 4 users Bob, Alice, Dan, Joe. Bob is a project managed, Alice and Dan are programmers under Bob and Joe is a random programmer on the internet who wants to help. Ideally in this system, Bob can commit any changes and won't require approval. Alice and Dan can commit to their branches, or a branch, but a commit to the trunk would need approval by Bob. This is where Joe comes in, wants to help, however, you just don't want to give him the keys to the kingdom just yet so to speak, so in my system you would setup a "low user" account. Any commits that Joe makes would need to be approved by Dan, Alice or both. However, in the system, Joe can build up "Karma" where after so many approved commits it would only need approval by one of the programmers, and then eventually no approval would be necessary. Does that make sense and do you know if a system like that exists? Or am I just crazy to even think such a system/environment would be possible?

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  • Distributed Lock Service over MySql/GigaSpaces/Netapp

    - by ripper234
    Disclaimer: I already asked this question, but without the deployment requirement. I got an answer that got 3 upvotes, and when I edited the question to include the deployment requirement the answer then became irrelevant. The reason I'm resubmitting is because SO considers the original question 'answered', even though I got no meaningful upvoted answer. I opened a uservoice submission about this problem. The reason I reposted is so StackOverflow consider the original question answered, so it doesn't show up on the 'unanswered questions' tab. Which distributed lock service would you use? Requirements are: A mutual exclusion (lock) that can be seen from different processes/machines lock...release semantics Automatic lock release after a certain timeout - if lock holder dies, it will automatically be freed after X seconds Java implementation Easy deployment - must not require complicated deployment beyond either Netapp, MySql or GigaSpaces. Must play well with those products (especially GigaSpaces - this is why TerraCotta was ruled out). Nice to have: .Net implementation If it's free: Deadlock detection / mitigation I'm not interested in answers like "it can be done over a database", or "it can be done over JavaSpaces" - I know. Relevant answers should only contain a ready, out-of-the-box, proven implementation.

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  • Distributed Cache with Serialized File as DataStore in Oracle Coherence

    - by user226295
    Weired but I am investigating the Oracle Coherence as a substitue for distribute cache. My primarr problem is that we dont have distribituted cache as such as of now in our app. Thats my major concern. And thats what I want to implement. So, lets say if I take up a machine and start a new (3rd) reading process, it will be able to connect to the cache and listen to the cache and will have a full set of cache triplicated (as of now its duplicated) Now thats waste from a common person stanpoint too. The size of the cache is 2 GB and without going distibuted its limiting us. Thats bring me to Coheremce. But now, we dont have database as persistent store too. we have the archival processes as our persistent store. (90 days worth of data) Ok now multiply that with soem where around 2 GB * 90 (thats the bare minimum we want to keep). Preliminary/Intermediate analysis of Coherence as a solution. And a (supposedly) brilliant thought crossed my mind. Why not have this as persistant storage with my distributed cache. Does Oracle Coherence support that. I will get rid of archiving infrastructure too (i hate daemon archiving processes). For some starnge reasons, I dont wanna go to the DB to replace those flat files. What say?, can Coherence be my savior? Any other stable alternate too. (Coherence is imposed on me by big guys, FYI)

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  • Experience with MooseFS?

    - by brown.2179
    Anyone have any experience using MooseFS? I want an easy distributed storage platform to store static data archive of about 10 TB and serve it to 20-40 nodes. Also I want to be able to add storage as the archive grows without having to rebuild the filesystem. I don't care if it's a bit slow. I just want it to be simple and stable. Basically from what I can see for OS X it's between MooseFS and Gluster. Any other suggestions?

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