Search Results

Search found 666 results on 27 pages for 'mongodb'.

Page 24/27 | < Previous Page | 20 21 22 23 24 25 26 27  | Next Page >

• Implementing the Reactive Manifesto with Azure and AWS

  - by Elton Stoneman

  Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2013/10/31/implementing-the-reactive-manifesto-with-azure-and-aws.aspxMy latest Pluralsight course, Implementing the Reactive Manifesto with Azure and AWS has just been published! I’d planned to do a course on dual-running a messaging-based solution in Azure and AWS for super-high availability and scale, and the Reactive Manifesto encapsulates exactly what I wanted to do. A “reactive” application describes an architecture which is inherently resilient and scalable, being event-driven at the core, and using asynchronous communication between components. In the course, I compare that architecture to a classic n-tier approach, and go on to build out an app which exhibits all the reactive traits: responsive, event-driven, scalable and resilient. I use a suite of technologies which are enablers for all those traits: ASP.NET SignalR for presentation, with server push notifications to the user Messaging in the middle layer for asynchronous communication between presentation and compute Azure Service Bus Queues and Topics AWS Simple Queue Service AWS Simple Notification Service MongoDB at the storage layer for easy HA and scale, with minimal locking under load. Starting with a couple of console apps to demonstrate message sending, I build the solution up over 7 modules, deploying to Azure and AWS and running the app across both clouds concurrently for the whole stack - web servers, messaging infrastructure, message handlers and database servers. I demonstrating failover by killing off bits of infrastructure, and show how a reactive app deployed across two clouds can survive machine failure, data centre failure and even whole cloud failure. The course finishes by configuring auto-scaling in AWS and Azure for the compute and presentation layers, and running a load test with blitz.io. The test pushes masses of load into the app, which is deployed across four data centres in Azure and AWS, and the infrastructure scales up seamlessly to meet the load – the blitz report is pretty impressive: That’s 99.9% success rate for hits to the website, with the potential to serve over 36,000,000 hits per day – all from a few hours’ build time, and a fairly limited set of auto-scale configurations. When the load stops, the infrastructure scales back down again to a minimal set of servers for high availability, so the app doesn’t cost much to host unless it’s getting a lot of traffic. This is my third course for Pluralsight, with Nginx and PHP Fundamentals and Caching in the .NET Stack: Inside-Out released earlier this year. Now that it’s out, I’m starting on the fourth one, which is focused on C#, and should be out by the end of the year.

  Read the article

• Keeping your options open in a cloud solution

  - by BuckWoody

  In on-premises solutions we have the full range of options open for a given computing solution – but we don’t always take advantage of them, for multiple reasons. Data goes in a Relational Database Management System, files go on a share, and e-mail goes to the Exchange server. Over time, vendors (including ourselves) add in functionality to one product that allow non-standard use of the platform. For example, SQL Server (and Oracle, and others) allow large binary storage in or through the system – something not originally intended for an RDBMS to handle. There are certainly times when this makes sense, of course, but often these platform hammers turn every problem into a nail. It can make us “lazy” in our design – we sometimes don’t take the time to learn another architecture because the one we’ve spent so much time with can handle what we want to do. But there’s a distinct danger here. In nature, when a population shares too many of the same traits, it can cause a complete collapse if a situation exploits a weakness shared by that population. The same is true with not using the righttool for the job in a computing environment. Your company or organization depends on your knowledge as a professional to select the best mix of supportable, flexible, cost-effective technologies to solve their problems, whether you’re in an architect role or not.  So take some time today to learn something new. The way I do this is to select a given problem, and try to solve it with a technology I’m not familiar with. For instance – create a Purchase Order system in Excel, then in Hadoop or MongoDB, or even in flat-files using PowerShell as an interface. No, I’m not suggesting any of these architectures are the proper way to solve the PO problem, but taking something concrete that you know well and applying that meta-knowledge to another platform will assist you in exercising the “little grey cells” and help you and your organization understand what is open to you. And of course you can do all of this on-premises – but my recommendation is to check out a cloud platform (my suggestion would of course be Windows Azure :) ) and try it there. Most providers (including Microsoft) provide free time to do that.

  Read the article

• Are separate business objects needed when persistent data can be stored in a usable format?

  - by Kylotan

  I have a system where data is stored in a persistent store and read by a server application. Some of this data is only ever seen by the server, but some of it is passed through unaltered to clients. So, there is a big temptation to persist data - whether whole rows/documents or individual fields/sub-documents - in the exact form that the client can use (eg. JSON), as this removes various layers of boilerplate, whether in the form of procedural SQL, an ORM, or any proxy structure which exists just to hold the values before having to re-encode them into a client-suitable form. This form can usually be used on the server too, though business logic may have to live outside of the object, On the other hand, this approach ends up leaking implementation details everywhere. 9 times out of 10 I'm happy just to read a JSON structure out of the DB and send it to the client, but 1 in every 10 times I have to know the details of that implicit structure (and be able to refactor access to it if the stored data ever changes). And this makes me think that maybe I should be pulling this data into separate business objects, so that business logic doesn't have to change when the data schema does. (Though you could argue this just moves the problem rather than solves it.) There is a complicating factor in that our data schema is constantly changing rapidly, to the point where we dropped our previous ORM/RDBMS system in favour of MongoDB and an implicit schema which was much easier to work with. So far I've not decided whether the rapid schema changes make me wish for separate business objects (so that server-side calculations need less refactoring, since all changes are restricted to the persistence layer) or for no separate business objects (because every change to the schema requires the business objects to change to stay in sync, even if the new sub-object or field is never used on the server except to pass verbatim to a client). So my question is whether it is sensible to store objects in the form they are usually going to be used, or if it's better to copy them into intermediate business objects to insulate both sides from each other (even when that isn't strictly necessary)? And I'd like to hear from anybody else who has had experience of a similar situation, perhaps choosing to persist XML or JSON instead of having an explicit schema which has to be assembled into a client format each time.

  Read the article

• Performance analytics via DBMS "plugins", or other solution

  - by Polynomial

  I'm working on a systems monitoring product that currently focuses on performance at the system level. We're expanding out to monitoring database systems. Right now we can fetch simple performance information from a selection of DBMS, like connection count, disk IO rates, lock wait times, etc. However, we'd really like a way to measure the execution time of every query going into a DBMS, without requiring the client to implement monitoring in their application code. Some potential solutions might be: Some sort of proxy that sits between client and server. SSL might be an issue here, plus it requires us to reverse engineer and implement the network protocol for each DBMS. Plugin for each DBMS system that automatically records performance information when a query comes in. Other problems include "anonymising" the SQL, i.e. taking something like SELECT * FROM products WHERE price > 20 AND name LIKE "%disk%" and producing SELECT * FROM products WHERE price > ? AND name LIKE "%?%", though this shouldn't be too difficult with some clever parsing and regex. We're mainly focusing on: MySQL MSSQL Oracle Redis mongodb memcached Are there any plugin-style mechanisms we can utilise for any of these? Or is there a simpler solution?

  Read the article

• How to push changes from Test server to Live server?

  - by anonymous

  As a beginner, I finally noticed the issue with making changes to the live server I've been working on, now that I have a couple users on it, since I bring it down so often. I created an EC2 image of my live server and set up a separate instance on EC2, so now I have 2 EC2 instances, Stage and Production. I set up GitHub and push changes to stage and test my code there, and when it's all done and working, I push it to the production branch, and everything is good. And there is a slight issue here since I name my files config_stage.js and config_production.js and set up .gitignore on each server, and in my code, I would have it read the ENV flags and set up the appropriate configs, is this the correct approach? And my main question is: how do you keep track of non-code changes to the server? For example, I installed HAProxy, Stunnel, Redis, MongoDB and several other things onto the Stage server for testing and now that it's all working and good, how do I deploy them to production? Right now, I'm just keeping track of everything I installed and copying configuration files over, which is very tedious and I'm afraid I may have missed a step somewhere. Is there a better way to port these changes over from my test server to my live server?

  Read the article

• deploy LAMP config to new boxes with low/no effort

  - by user1444233

  I'm spending a lot of time setting up new Centos 6 instances. I use a VCS (Subversion) for most of the config files and all of the webapp source files (Github), but even with excellent package managers (like yum, npm, easy_install, etc.) it still takes time. I'd like to get to the point where I could try out a new potential web host by just signing up for an account, logging in and automatically sucking my standardised config onto the box. I know there are a set of tools that can help: Puppet Chef Vagrant and a set of services that sell solutions: [Jumpbox] http://www.jumpbox.com/ [BitNami Cloud] http://bitnami.org/cloud I don't mind investing time in learning a new tool, but as a no-budget start-up, I'm keen to keep monthly costs down. My biggest concern is that time spent on the server config is time away from the codebase, and that's where I think my team and I should be investing our energy, at least until we get funded and scale up a bit. I'd be grateful of some recommendations for which way to jump on config: stick with SSH and manual deploys, at least until you get big. bite the bullet and learn [say] puppet. You may only use it 8-10 times, but it pays to have such an easy tunable server bootstrap. don't bother, just pay the $100/month for a standard config service. It'll cost you $1000/year, but you should focus on the code. Other questions in this domain I use quite a complex stack (Drupal, Zend Server, MySQL, PHP, MongoDB, Python, django), but are there standard(ish) setups that include these or that I could build upon more quickly? Are the configs optimised for small, medium, large VPS (1GB, 4GB, 16GB)? How secure are they?

  Read the article

• Should windows services be created with custom users, or should I use one of LocalSystem/LocalServic

  - by Justin Dearing

  I'm asking the question in general for the average custom developed NT service or unix OSS daemon ported to windows with SCM support. However, at the moment my immediate concern is for mongodb. From my experience with UNIX I like all my services to run as different unprivileged users. The way this has translated to windows is as follows: Create a local (or domain if it has to talk to SQL server) windows user with a long random password (lately an ASCII85 encoded guid generated from a different machine). Set it to next expire and forbid it from changing its password. Remove that user from the "Users Group". Grant that user "Login as a Service" permission. Give it read permission to the folder where the app resides, and write permission to the logs and data files the applications use. Assign the user to the service. Troubleshoot until the service starts. My feeling is that the unprivileged users are less powerful than the 3 special service users. I also feel that by isolating which users run which services, I would limit collateral damage if a way to compromise one service was found.

  Read the article

• Building a Web proxy to get around same-origin restrictions for collaborative Webapp based on a MEAN stack

  - by Lew Cohen

  Can anyone point to books, articles, blogs, or even applications - open-source or proprietary - that detail building a Web proxy? This specific proxy will exist to get around the same-origin restrictions that prevent, for instance, loading a given Website into an <iframe> in a Webapp. This Webapp is a collaborative application in which a group of users log in to the app's Website and can then load different Websites into this app's <iframe> and do various collaborative things (e.g., several users simultaneously browsing a Website, in synch). The Webapp itself is built on a MEAN stack (MongoDB, Express, AngularJS, and Node.js). The purpose of this proxy is not to do anonymous browsing or to bypass censorship. Information on how to build such a vehicle seems not to be readily available from my research. I've come across Glype but am not sure whether this is a feasible solution. I don't want to reinvent the wheel, so if a product is available for purchase, great. Else, we'd need to build one. The one that seems to be close is http://www.corsproxy.com. In effect, we'd like to re-create this since it evidently does what's needed. I don't care what server-side technology is used. Our app is MEAN-based, if that has any bearing. Also, the proxy has to obviously honor basic security considerations (user cookies, etc.) and eventually be scalable. So, anyone know of any sources that would detail how to build one of these? Is it even worth building if something already exists? If so, what would be a good candidate? Any other issues that should be considered with this proxy/application? Thanks a lot!

  Read the article

• Developing high-performance and scalable zend framework website [on hold]

  - by Daniel

  We are going to develop an ads website like http://www.gumtree.com/ (it will not be like this one but just to give you an ideea) and we are having some issues regarding performance and scalability. We are planning on using Zend Framework for this project but this is all that I'm sure off at this point. I don't think a classic approch like Zend Framework (PHP) + MySQL + Memcache + jQuery (and I would throw Doctrine 2 in there to) will fix result in a high-performance application. I was thinking on making this a RESTful application (with Zend Framework) + NGINX (or maybe MongoDB) + Memcache (or eAccelerator -- I understand this will create problems with scalability on multiple servers) + jQuery or maybe throw Backbone.js in there, a CDN for static content, a server for images and a scalable server for the requests and the rest. My questions are: - What do you think about my approch? - What solutions would you recommand for developing an high performance, scalable application expected to have a lot of traffic using PHP(Zend Framework 2)...I would be interested in your approch. I should note that I'm a Zend developer, I'm working with Zend for over 3 years, this is why I'm choosing it.

  Read the article

• How to push changes from Test server to Live server?

  - by anonymous

  As a beginner, I finally noticed the issue with making changes to the live server I've been working on, now that I have a couple users on it, since I bring it down so often. I created an EC2 image of my live server and set up a separate instance on EC2, so now I have 2 EC2 instances, Stage and Production. I set up GitHub and push changes to stage and test my code there, and when it's all done and working, I push it to the production branch, and everything is good. And there is a slight issue here since I name my files config_stage.js and config_production.js and set up .gitignore on each server, and in my code, I would have it read the ENV flags and set up the appropriate configs, is this the correct approach? And my main question is: how do you keep track of non-code changes to the server? For example, I installed HAProxy, Stunnel, Redis, MongoDB and several other things onto the Stage server for testing and now that it's all working and good, how do I deploy them to production? Right now, I'm just keeping track of everything I installed and copying configuration files over, which is very tedious and I'm afraid I may have missed a step somewhere. Is there a better way to port these changes over from my test server to my live server?

  Read the article

• What are the right questions to ask when deciding whether to use Chef or Puppet?

  - by John Feminella

  I am about to start a new project which will, in part, require deploying many identical nodes of approximately three different classes: Data nodes, which will run sharded instances of MongoDB. Application nodes, which will run instances of a Ruby on Rails application and an older ASP.NET MVC application. Processing nodes, which will run jobs requested by the application nodes. ALl the nodes will run on instances of Ubuntu 10.04, though they will have different packages installed. I have some familiarity with Chef from previous projects, though I don't consider myself an expert. In an effort to do due diligence, I have been investigating alternative possibilities. We have a number of folks in-house who are long-time Puppet users, and they have encouraged me to take a look. I am having trouble evaluating both choices, though. Chef and Puppet share many of the same domain terminology -- packages, resources, attributes, and so on, and they have a common history that stems from taking different approaches to the same problem. So in some sense they are very similar. But much of the comparison information I've found, like this article, is a little outdated. If you were starting this project today, what questions would you ask yourself to decide whether you should use Chef or Puppet for configuration management? (Note: I don't want answer to the question "Should I use Chef or Puppet?")

  Read the article

• Newbie, deciding Python or Erlang

  - by Joe

  Hi Guys, I'm a Administrator (unix, Linux and some windows apps such as Exchange) by experience and have never worked on any programming language besides C# and scripting on Bash and lately on powershell. I'm starting out as a service provider and using multiple network/server monitoring tools based on open source (nagios, opennms etc) in order to monitor them. At this moment, being inspired by a design that I came up with, to do more than what is available with the open source at this time, I would like to start programming and test some of these ideas. The requirement is that a server software that captures a stream of data and store them in a database(CouchDB or MongoDB preferably) and the client side (agent installed on a server) would be sending this stream of data on a schedule of every 10 minutes or so. For these two core ideas, I have been reading about Python and Erlang besides ruby. I do plan to use either Amazon or Rackspace where the server platform would run. This gives me the scalability needed when we have more customers with many servers. For that reason alone, I thought Erlang was a better fit(I could be totally wrong, new to this game) and I understand that Erlang has limited support in some ways compared to Ruby or Python. But also I'm totally new to the programming realm of things and any advise would be appreciated grately. Jo

  Read the article

• How to create this MongoMapper custom data type?

  - by Kapslok

  I'm trying to create a custom MongoMapper data type in RoR 2.3.5 called Translatable: class Translatable < String def initialize(translation, culture="en") end def languages end def has_translation(culture)? end def self.to_mongo(value) end def self.from_mongo(value) end end I want to be able to use it like this: class Page include MongoMapper::Document key :title, Translatable, :required => true key :content, String end Then implement like this: p = Page.new p.title = "Hello" p.title(:fr) = "Bonjour" p.title(:es) = "Hola" p.content = "Some content here" p.save p = Page.first p.languages => [:en, :fr, :es] p.has_translation(:fr) => true en = p.title => "Hello" en = p.title(:en) => "Hello" fr = p.title(:fr) => "Bonjour" es = p.title(:es) => "Hola" In mongoDB I imagine the information would be stored like: { "_id" : ObjectId("4b98cd7803bca46ca6000002"), "title" : { "en" : "Hello", "fr" : "Bonjour", "es" : "Hola" }, "content" : "Some content here" } So Page.title is a string that defaults to English (:en) when culture is not specified. I would really appreciate any help.

  Read the article

• Is Berkeley DB XML a viable database backend?

  - by w00t

  Apparently, BDB-XML has been around since at least 2003 but I only recently stumbled upon it on Oracle's website: Berkeley DB XML. Here's the blurb: Oracle Berkeley DB XML is an open source, embeddable XML database with XQuery-based access to documents stored in containers and indexed based on their content. Oracle Berkeley DB XML is built on top of Oracle Berkeley DB and inherits its rich features and attributes. Like Oracle Berkeley DB, it runs in process with the application with no need for human administration. Oracle Berkeley DB XML adds a document parser, XML indexer and XQuery engine on top of Oracle Berkeley DB to enable the fastest, most efficient retrieval of data. To me it seems that the underlying ideas are technically sound and probably more mature than the newer document-based DBs like CouchDB or MongoDB. It has support for C, C++, Ruby and Perl, as far as I can determine. It even has HA-capabilities like automatic replication using a master/slave model with automatic election. However, I can't seem to find any projects that use it. Is there something fundamentally wrong with it? Is the license too onerous? Is it too complicated? Why is it not being used?

  Read the article

• Is there an "embedded DBMS" to support multiple writer applications (processes) on the same db files

  - by Amir Moghimi

  I need to know if there is any embedded DBMS (preferably in Java and not necessarily relational) which supports multiple writer applications (processes) on the same set of db files. BerkeleyDB supports multiple readers but just one writer. I need multiple writers and multiple readers. UPDATE: It is not a multiple connection issue. I mean I do not need multiple connections to a running DBMS application (process) to write data. I need multiple DBMS applications (processes) to commit on the same storage files. HSQLDB, H2, JavaDB (Derby) and MongoDB do not support this feature. I think that there may be some File System limitations that prohibit this. If so, is there a File System that allows multiple writers on a single file? Use Case: The use case is a high-throughput clustered system that intends to store its high-volume business log entries into a SAN storage. Storing business logs in separate files for each server does not fit because query and indexing capabilities are needed on the whole biz logs. Because "a SAN typically is its own network of storage devices that are generally not accessible through the regular network by regular devices", I want to use SAN network bandwidth for logging while cluster LAN bandwidth is being used for other server to server and client to server communications.

  Read the article

• MongoMapper won't let me create an object

  - by Jade

  I'm just learning MongoDB and MongoMapper. This is on Rails 3. I created a blog in app/models/blog.rb: class Blog include MongoMapper::Document key :title, String, :required => true key :body, Text timestamps! end I go into the Rails console: rails c Loading development environment (Rails 3.0.0.beta) ruby-1.9.1-p378 > **b = Blog.new** NoMethodError: undefined method `from_mongo' for Text:Module from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/mongo_mapper-0.7.2/lib/mongo_mapper/plugins/keys.rb:323:in `get' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/mongo_mapper-0.7.2/lib/mongo_mapper/plugins/keys.rb:269:in `read_key' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/mongo_mapper-0.7.2/lib/mongo_mapper/plugins/keys.rb:224:in `[]' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/mongo_mapper-0.7.2/lib/mongo_mapper/plugins/inspect.rb:7:in `block in inspect' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/mongo_mapper-0.7.2/lib/mongo_mapper/plugins/inspect.rb:6:in `collect' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/mongo_mapper-0.7.2/lib/mongo_mapper/plugins/inspect.rb:6:in `inspect' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/railties-3.0.0.beta/lib/rails/commands/console.rb:47:in `start' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/railties-3.0.0.beta/lib/rails/commands/console.rb:8:in `start' from /Users/jade/.rvm/gems/ruby-1.9.1-p378/gems/railties-3.0.0.beta/lib/rails/commands.rb:34:in `<top (required)>' from /Users/jade/code/farmerjade/script/rails:10:in `require' from /Users/jade/code/farmerjade/script/rails:10:in `<main>' Am I overlooking something really dumb, or is this something in my setup? I'm using the mongo_mapper version you get by adding it to your Gemfile, so I'm wondering if it might be that. I'd appreciate any suggestions!

  Read the article

• Backbone Model fetched from Lithium controller is not loaded properly in bb Model

  - by Nilesh Kale

  I'm using backbone.js and Lithium. I'm fetching a model from the server by passing in a _id that is received as a hidden parameter on the page. The database MongoDB has stored the data correctly and can be viewed from console as: { "_id" : ObjectId("50bb82694fbe3de417000001"), "holiday_name" : "SHREE15", "description": "", "star_rating" : "3", "holiday_type" : "family", "rooms" : "1", "adults" : "2", "child" :"0", "emails" : "" } The Lithium Model class is so: class Holidays extends \lithium\data\Model { public $validates = array( 'holiday_name' => array( array( 'notEmpty', 'required' => true, 'message' => 'Please key-in a holiday name! (eg. Family trip for summer holidays)' ))); } The backbone Holiday model is so: window.app.IHoliday = Backbone.Model.extend({ urlRoot: HOLIDAY_URL, idAttribute: "_id", id: "_id", // Default attributes for the holiday. defaults: { }, // Ensure that each todo created has `title`. initialize: function(props) { }, The code for backbone/fetch is: var Holiday = new window.app.IHoliday({ _id: holiday_id }); Holiday.fetch( { success: function(){ alert('Holiday fetched:' + JSON.stringify(Holiday)); console.log('HOLIDAY Fetched: \n' + JSON.stringify(Holiday)); console.log('Holiday name:' + Holiday.get('holiday_name')); } } ); Lithium Controller Code is: public function load($holiday_id) { $Holiday = Holidays::find($holiday_id); return compact('Holiday'); } PROBLEM: The output of the backbone model fetched from server is as below and the Holiday model is not correctly 'formed' when data returns into backbone Model: HOLIDAY Fetched: {"_id":"50bb82694fbe3de417000001","Holiday":{"_id":"50bb82694fbe3de417000001","holiday_name":"SHREE15","description":"","star_rating":"3","holiday_type":"family","rooms":"1","adults":"2","child":"0","emails":""}} iplann...view.js (line 68) Holiday name:undefined Clearly there is some issue when the data is passed/translated from Lithium and loaded up as a model into backbone Holiday model. Is there something very obviously wrong in my code?

  Read the article

• What would cause native gem extensions on OS X to build but fail to load?

  - by goodmike

  I am having trouble with some of my rubygems, in particular those that use native extensions. I am on a MacBookPro, with Snow Leopard. I have XCode 3.2.1 installed, with gcc 4.2.1. Ruby 1.8.6, because I'm lazy and a scaredy cat and don't want to upgrade yet. Ruby is running in 32-bit mode. I built this ruby from scratch when my MBP ran OSX 10.4. When I require one of the affected gems in irb, I get a Load Error for the gem extension's bundle file. For example, here's nokogigi dissing me: > require 'rubygems' = true > require 'nokogiri' LoadError: Failed to load /usr/local/lib/ruby/gems/1.8/gems/nokogiri-1.4.1/lib/nokogiri/nokogiri.bundle This is also happening with the Postgres pg and MongoDB mongo gems. My first thought was that the extensions must not be building right. But gem install wasn't throwing any errors. So I reinstalled with the verbose flag, hoping to see some helpful warnings. I've put the output in a Pastie, and the only warning I see is a consistent one about "passing argument n of ‘foo’ with different width due to prototype." I suspect that this might be an issue from upgrading to Snow Leopard, but I'm a little surprised to experience it now, since I've updated my XCode. Could it stem from running Ruby in 1.8.6? I'm embarrassed that I don't know quite enough about my Mac and OSX to know where to look next, so any guidance, even just a pointer to some document I couldn't find via Google, would be most welcome. Michael

  Read the article

• Why are references compacted inside Perl lists?

  - by parkan

  Putting a precompiled regex inside two different hashes referenced in a list: my @list = (); my $regex = qr/ABC/; push @list, { 'one' => $regex }; push @list, { 'two' => $regex }; use Data::Dumper; print Dumper(\@list); I'd expect: $VAR1 = [ { 'one' => qr/(?-xism:ABC)/ }, { 'two' => qr/(?-xism:ABC)/ } ]; But instead we get a circular reference: $VAR1 = [ { 'one' => qr/(?-xism:ABC)/ }, { 'two' => $VAR1->[0]{'one'} } ]; This will happen with indefinitely nested hash references and shallowly copied $regex. I'm assuming the basic reason is that precompiled regexes are actually references, and references inside the same list structure are compacted as an optimization (\$scalar behaves the same way). I don't entirely see the utility of doing this (presumably a reference to a reference has the same memory footprint), but maybe there's a reason based on the internal representation Is this the correct behavior? Can I stop it from happening? Aside from probably making GC more difficult, these circular structures create pretty serious headaches. For example, iterating over a list of queries that may sometimes contain the same regular expression will crash the MongoDB driver with a nasty segfault (see https://rt.cpan.org/Public/Bug/Display.html?id=58500)

  Read the article

• What's a good Java-based Master-Slave communication mechanism?

  - by plecong

  I'm creating a Java application that requires master-slave communication between JVMs, possibly residing on the same physical machine. There will be a "master" server running inside a JEE application server (i.e. JBoss) that will have "slave" clients connect to it and dynamically register itself for communication (that is the master will not know the IP addresses/ports of the slaves so cannot be configured in advance). The master server acts as a controller that will dole work out to the slaves and the slaves will periodically respond with notifications, so there would be bi-directional communication. I was originally thinking of RPC-based systems where each side would be a server, but it could get complicated, so I'd prefer a mechanism where there's an open socket and they talk back and forth. I'm looking for a communication mechanism that would be low-latency where the messages would be mostly primitive types, so no serious serialization is necessary. Here's what I've looked at: RMI JMS: Built-in to Java, the "slave" clients would connect to the existing ConnectionFactory in the application server. JAX-WS/RS: Both master and slave would be servers exposing an RPC interface for bi-directional communication. JGroups/Hazelcast: Use shared distributed data structures to facilitate communication. Memcached/MongoDB: Use these as "queues" to facilitate communication, though the clients would have to poll so there would be some latency. Thrift: This does seem to keep a persistent connection, but not sure how to integrate/embed a Thrift server into JBoss WebSocket/Raw Socket: This would work, but require a lot more custom code than I'd like. Is there any technology I'm missing? Edit: Also looked at: JMX: Have the client connect to JBoss' JMX server and receive JMX notifications for bidirectional comms.

  Read the article

• how does one _model_ data from relational databases in clojure ?

  - by sandeep

  I have asked this question on twitter as well the #clojure IRC channel, yet got no responses. There have been several articles about Clojure-for-Ruby-programmers, Clojure-for-lisp-programmers.. but what is the missing part is Clojure for ActiveRecord programmers . There have been articles about interacting with MongoDB, Redis, etc. - but these are key value stores at the end of the day. However, coming from a Rails background, we are used to thinking about databases in terms of inheritance - has_many, polymorphic, belongs_to, etc. The few articles about Clojure/Compojure + MySQL (ffclassic) - delve right into sql. Of course, it might be that an ORM induces impedence mismatch, but the fact remains that after thinking like ActiveRecord, it is very difficult to think any other way. I believe that relational DBs, lend themselves very well to the object-oriented paradigm because of them being , essentially, Sets. Stuff like activerecord is very well suited for modelling this data. For e.g. a blog - simply put class Post < ActiveRecord::Base has_many :comments end class Comment < ActiveRecord::Base belongs_to :post end How does one model this in Clojure - which is so strictly anti-OO ? Perhaps the question would have been better if it referred to all functional programming languages, but I am more interested from a Clojure standpoint (and Clojure examples)

  Read the article

• Problems using (building?) native gem extensions on OS X

  - by goodmike

  I am having trouble with some of my rubygems, in particular those that use native extensions. I am on a MacBookPro, with Snow Leopard. I have XCode 3.2.1 installed, with gcc 4.2.1. Ruby 1.8.6, because I'm lazy and a scaredy cat and don't want to upgrade yet. Ruby is running in 32-bit mode. I built this ruby from scratch when my MBP ran OSX 10.4. When I require one of the affected gems in irb, I get a Load Error for the gem extension's bundle file. For example, here's nokogigi dissing me: > require 'rubygems' = true > require 'nokogiri' LoadError: Failed to load /usr/local/lib/ruby/gems/1.8/gems/nokogiri-1.4.1/lib/nokogiri/nokogiri.bundle This is also happening with the Postgres pg and MongoDB mongo gems. My first thought was that the extensions must not be building right. But gem install wasn't throwing any errors. So I reinstalled with the verbose flag, hoping to see some helpful warnings. I've put the output in a Pastie, and the only warning I see is a consistent one about "passing argument n of ‘foo’ with different width due to prototype." I suspect that this might be an issue from upgrading to Snow Leopard, but I'm a little surprised to experience it now, since I've updated my XCode. Could it stem from running Ruby in 1.8.6? I'm embarrassed that I don't know quite enough about my Mac and OSX to know where to look next, so any guidance, even just a pointer to some document I couldn't find via Google, would be most welcome. Michael

  Read the article

• Spring: Bean fails to read off values from external Properties file when using @Value annotation

  - by daydreamer

  XML Configuration <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"> <util:properties id="mongoProperties" location="file:///storage/local.properties" /> <bean id="mongoService" class="com.business.persist.MongoService"></bean> </beans> and MongoService looks like @Service public class MongoService { @Value("#{mongoProperties[host]}") private String host; @Value("#{mongoProperties[port]}") private int port; @Value("#{mongoProperties[database]}") private String database; private Mongo mongo; private static final Logger LOGGER = LoggerFactory.getLogger(MongoService.class); public MongoService() throws UnknownHostException { LOGGER.info("host=" + host + ", port=" + port + ", database=" + database); mongo = new Mongo(host, port); } public void putDocument(@Nonnull final DBObject document) { LOGGER.info("inserting document - " + document.toString()); mongo.getDB(database).getCollection(getCollectionName(document)).insert(document, WriteConcern.SAFE); } I write my MongoServiceTest as public class MongoServiceTest { @Autowired private MongoService mongoService; public MongoServiceTest() throws UnknownHostException { mongoRule = new MongoRule(); } @Test public void testMongoService() { final DBObject document = DBContract.getUniqueQuery("001"); document.put(DBContract.RVARIABLES, "values"); document.put(DBContract.PVARIABLES, "values"); mongoService.putDocument(document); } and I see failures in tests as 12:37:25.224 [main] INFO c.s.business.persist.MongoService - host=null, port=0, database=null java.lang.NullPointerException at com.business.persist.MongoServiceTest.testMongoService(MongoServiceTest.java:40) Which means bean was not able to read the values from local.properties local.properties ### === MongoDB interaction === ### host="127.0.0.1" port=27017 database=contract How do I fix this? update It doesn't seem to read off the values even after creating setters/getters for the fields. I am really clueless now. How can I even debug this issue? Thanks much!

  Read the article

• Rails Heroku Gemfile.lock error - push rejected (open source)

  - by KJ50

  I am trying to push my open source RoR application to Heroku but I'm having an issue making the initial push. I have read many similar questions, but none of those answers has helped to solve my problem. I have tried bundle update and bundle install various times. I also have tried removing and then re-committing my Gemfile.lock file, however I get this same error still... $ git push heroku master Counting objects: 5199, done. Compressing objects: 100% (3086/3086), done. Writing objects: 100% (5199/5199), 4.57 MiB | 131 KiB/s, done. Total 5199 (delta 3418), reused 3152 (delta 1962) -----> Removing .DS_Store files -----> Ruby app detected -----> Compiling Ruby/NoLockfile ! ! Gemfile.lock required. Please check it in. ! ! Push rejected, failed to compile Ruby app To [email protected]:frozen-springs-4725.git ! [remote rejected] master -> master (pre-receive hook declined) error: failed to push some refs to '[email protected]:frozen-springs-4725.git' Since my application uses MongoDB with MongoMapper, I suspect that I have some configuration incorrect. My code can be found here on Github (I'm currently working on the heroku branch). Feel free to clone our repository and try it yourself. If anyone has any insight which could help me resolve this issue I would be very thankful!

  Read the article

• Architecture of finding movable geotagged objects

  - by itsme

  I currently have a Postgres DB filled with approx. 300.000 data-sets of moving vehicles all over the world. My very frequently repeated query is: Give me all vehicles in a 5/10/20mile radius. Currently I spend around 600 to 1200 ms in the DB to prepare the set of located vehicle-objects. I am looking to vastly improve this time by ideally one or two orders of magnitude if possible. I am working in a Ruby on Rails 3.0beta environment if this is relevant. Any ideas how to architect the whole system to accelerate this query? Any NoSQL database able to deliver this kind of geolocation performance? I know of MongoDB working on an extension to facilitate this scenario but haven't tried it yet. Any intelligent use of Redis to achieve this? One problem with SQL-DBs here seems to be that I can't possibly use indexes because my vehicles are mostly moving around, meaning I had to constantly created DB indexes which, by itself, is probably more expensive than just doing the searching without index. Looking forward to your thoughs, Thanks!

  Read the article

< Previous Page | 20 21 22 23 24 25 26 27  | Next Page >