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  • MongoDB Schema Design - Real-time Chat

    - by Nick
    I'm starting a project which I think will be particularly suited to MongoDB due to the speed and scalability it affords. The module I'm currently interested in is to do with real-time chat. If I was to do this in a traditional RDBMS I'd split it out into: Channel (A channel has many users) User (A user has one channel but many messages) Message (A message has a user) The the purpose of this use case, I'd like to assume that there will be typically 5 channels active at one time, each handling at most 5 messages per second. Specific queries that need to be fast: Fetch new messages (based on an bookmark, time stamp maybe, or an incrementing counter?) Post a message to a channel Verify that a user can post in a channel Bearing in mind that the document limit with MongoDB is 4mb, how would you go about designing the schema? What would yours look like? Are there any gotchas I should watch out for?

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  • Rails and MongoDB with MongoMapper

    - by FCastellanos
    I'm new to Rails development and I'm starting with MongoDB also. I have been following this Railscast tutorial about complex forms with Rails but I'm using MongoDB as my database. I'm having no problems inserting documents with it's childs and retrieving the data to the edit form, but when I try to update it I get this error undefined method `assert_valid_keys' for false:FalseClass this is my entity class class Project include MongoMapper::Document key :name, String, :required => true key :priority, Integer many :tasks after_update :save_tasks def task_attributes=(task_attributes) task_attributes.each do |attributes| if attributes[:id].blank? tasks.build(attributes) else task = tasks.detect { |t| t.id.to_s == attributes[:id].to_s } task.attributes = attributes end end end def save_tasks tasks.each do |t| t.save(false) end end end Does anyone knows whats happening here? Thanks

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  • MongoDB: embedding performance question

    - by Alex
    I just started learning MongoDB, and I really like the idea of embedding collections instead of referencing them. MongoDB's documentation recommends to use embedding if performance is needed. I just thought about a simple forum model. Let's say, every board category has several boards, every board has several topics, and every topic has several messages. All of these collections are embedded. After some time the size of the board category will be huge. Way more than the 2MB limit. Does this mean that there's a flaw in this design?

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  • MongoDB db.serverStatus() gives error when running using tunnel that is targetted to api.cloudfoundry.com

    - by Ajay
    Following is the console session... C:\Users\xxx>vmc tunnel myMongoDB Getting tunnel connection info: OK Service connection info: username : uuuu password : pppp name : db url : mongodb://uuuu:[email protected]:25200/db Starting tunnel to myMongoDB on port 10000. 1: none 2: mongo 3: mongodump 4: mongorestore Which client would you like to start?: 2 Launching 'mongo --host localhost --port 10000 -u uuuu -p pppp db' MongoDB shell version: 2.0.6 connecting to: localhost:10000/db > db.serverStatus() { "errmsg" : "need to login", "ok" : 0 } > Which credentials should I use to login (assuming should use db.auth) to get rid of the error "{ "errmsg" : "need to login", "ok" : 0 }". When I run the same in micro CF on my machine it works ok and gives me the expected output. P.S. I'm trying this to get to know the current connections on my application, written in node.js. Trying to debug some issues with connections to the DB. If there is any other alternative that I can use please suggest that as well.

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  • Facebook user_id as MongoDB BSON ObjectId?

    - by MattDiPasquale
    I'm rebuilding Lovers on Facebook with Sinatra & Redis. I like Redis because it doesn't have the long (12-byte) BSON ObjectIds and I am storing sets of Facebook user_ids for each user. The sets are requests_sent, requests_received, & relationships, and they all contain Facebook user ids. I'm thinking of switching to MongoDB because I want to use it's geospatial indexing. If I do, I'd want to use the FB user ids as the _id field because I want the sets to be small and I want the JSON responses to be small. But, is the BSON ObjectId better (more efficient for MongoDB) to use than just an integer (fb user_id)?

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  • What is the recommended MongoDB schema for this quiz-engine scenario?

    - by hughesdan
    I'm working on a quiz engine for learning a foreign language. The engine shows users four images simultaneously and then plays an audio file. The user has to match the audio to the correct image. Below is my MongoDB document structure. Each document consists of an image file reference and an array of references to audio files that match that image. To generate a quiz instance I select four documents at random, show the images and then play one audio file from the four documents at random. The next step in my application development is to decide on the best document schema for storing user guesses. There are several requirements to consider: I need to be able to report statistics at a user level. For example, total correct answers, total guesses, mean accuracy, etc) I need to be able to query images based on the user's learning progress. For example, select 4 documents where guess count is 10 and accuracy is <=0.50. The schema needs to be optimized for fast quiz generation. The schema must not cause future scaling issues vis a vis document size. Assume 1mm users who make an average of 1000 guesses. Given all of this as background information, what would be the recommended schema? For example, would you store each guess in the Image document or perhaps in a User document (not shown) or a new document collection created for logging guesses? Would you recommend logging the raw guess data or would you pre-compute statistics by incrementing counters within the relevant document? Schema for Image Collection: _id "505bcc7a45c978be24000005" date 2012-09-21 02:10:02 UTC imageFileName "BD3E134A-C7B3-4405-9004-ED573DF477FE-29879-0000395CF1091601" random 0.26997075392864645 user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioFiles [ 0 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "English" date 2012-09-22 01:15:04 UTC } 1 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "Spanish" date 2012-09-22 01:17:04 UTC } ]

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  • MSVC Compiler options with mojo-native in Maven

    - by graham.reeds
    I'm trying to set up a test environment with Maven to build VC++ and I am way behind on this. I have 3 source files that I builds a dll (once I get this fixed it should be a simple matter to add the unit-tests): hook.cpp hook.h hook.def This is compiled, on the command line, with the following: C:\Develop\hook\src\main\msvc>cl -o hook.dll Hook.cpp /D HOOK_DLLEXPORT /link /DLL /DEF:"Hook.def" Which produces the expected obj, dll, lib and exp files. So now to get this working in Maven2 with the Mojo-native plugin. With no options Maven w/Mojo gives me this (truncated) output: [INFO] [native:initialize {execution: default-initialize}] [INFO] [native:unzipinc {execution: default-unzipinc}] [INFO] [native:javah {execution: default-javah}] [INFO] [native:compile {execution: default-compile}] [INFO] cmd.exe /X /C "cl -IC:\Develop\hook\src\main\msvc /FoC:\Develop\hook\targ et\objs\Hook.obj -c C:\Develop\hook\src\main\msvc\Hook.cpp" Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.30729.01 for 80x86 Copyright (C) Microsoft Corporation. All rights reserved. Hook.cpp [INFO] [native:link {execution: default-link}] [INFO] cmd.exe /X /C "link.exe /out:C:\Develop\hook\target\hook.dll target\objs\ Hook.obj" Microsoft (R) Incremental Linker Version 9.00.30729.01 Copyright (C) Microsoft Corporation. All rights reserved. LINK : fatal error LNK1561: entry point must be defined [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Error executing command line. Exit code:1561 mojo-native gives options for manipulating the compiler/linker options but gives no example of usage. No matter what I tweak in these settings I get the error of: [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Failed to configure plugin parameters for: org.codehaus.mojo:native-maven -plugin:1.0-alpha-4 (found static expression: '-o hook.dll Hook.cpp /D HOOK_DLLEXPORT /link /DLL /DEF:"Hook.def"' which may act as a default value). Cause: Cannot assign configuration entry 'compilerStartOptions' to 'interface ja va.util.List' from '-o hook.dll Hook.cpp /D HOOK_DLLEXPORT /link /DLL /DEF:"Hook .def"', which is of type class java.lang.String The relevant part of my pom.xml looks like this: <configuration> <sources> <source> <directory>src/main/msvc</directory> <includes> <include>**/*.cpp</include> </includes> </source> </sources> <compilerProvider>msvc</compilerProvider> <compilerExecutable>cl</compilerExecutable> <!-- cl -o hook.dll Hook.cpp /D HOOK_DLLEXPORT /link /DLL /DEF:"Hook.def" --> <compilerStartOptions>-o hook.dll Hook.cpp /D HOOK_DLLEXPORT /link /DLL /DEF:"Hook.def"</compilerStartOptions> <!-- <compilerMiddleOptions></compilerMiddleOptions> <compilerEndOptions></compilerEndOptions> <linkerStartOptions></linkerStartOptions> <linkerMiddleOptions></linkerMiddleOptions> <linkerEndOptions></linkerEndOptions> --> </configuration> How do I manipulate the compiler to produce a DLL like the command line version does? Or should I give up and just use exec?

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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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  • Is MongoDB a good choice or not for my application?

    - by shubham
    I have a Reporting application which stores the reports in xml format as recieved from source (XML schema is not defined, it can be any format) and those reports contain some keys and values. Like jobid, setid be keys for 1 type of report and userid, groupId for another type of report etc. The type of keys that can be referred from the document is determined by the namespaces used in the xml doc. These keys are stored on the basis of namespace used in the xml document. For e.g. If a tag in xml fragment uses namespace= "myspace1", then I have keys A and B for myspace1 stored in another table. It will fetch those keys from that table for this namespace, look for their values in xml doc and store it in another table along with the pointer to this xml document (Id of a record storing complete xml document in a cell). Use cases: When the user comes and queries for that key and value, I return the document or a set of documents that are having those key/value pairs. When the user comes and queries for a certain key and provide a name for xslt (pre stored), I fetch the set of documents fulfilling that criteria and convert that xml to html with the specified xslt. When the user comes and asks for a particular fragment of a doc then it can fetch a subset from a particular document also. When the user comes and queries for top x values of a certain key, I return the set of documents that are having top 10 values of that key. I am using DB2 database for its support of xml along with relational capabilities. That makes easier for me to run xpath expressions and fetch values of keys and also aggregate a set of documents fullfilling a criteria, all on the database side. Problems: DB2 stores XML doc of upto 2GB in size. Retrieval is very slow. If some thing involves many documents, then it takes significant time for things to show up in browser, and the user has to wait. Can MongoDb help in this case, as it is document oriented? can I do xml related xpath queries and document transformations on db side? Or is it ok to use both in such a case?

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  • PHP Socket Server vs node.js: Web Chat

    - by Eliasdx
    I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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  • node.js beginner tutorials?

    - by TreyK
    Hey all, I'm working on creating my first real node.js http server, and I'm sort of drowning in it. As a good teacher of mine always said, "I'll just shove you in the water for now, and then I'll show you how to swim." Fortunately, she wasn't a swimming instructor, but it's a good analogy nonetheless. I feel like I've jumped into node.js and I've only found a ping pong ball to help, that is to say, most of the tutorials I've read stop shortly after the "Hello World" example and I've mostly been trying to make sense of copied and pasted code (or they assume I have knowledge of lower level HTTP and webserver concepts that have been done for me as an Apache/PHP developer). I have experience in both client-side Javascript and PHP, but node seems to be a beast all of its own. I don't quite have the low-level knowledge that seems necessary for creating a node server, and connect, which seems to be a nice module for simplifying things, seems quite sparsely explained, even in the docs on its Git. Where could I find some tutorials to help me in this situation? TL;DR - Are there any tutorials for node.js that go beyond "Hello World" but don't require much low-level knowledge? Or any tutorials that explain lower-level HTTP and webserver concepts that I would need to effectively create a node HTTP server? Thanks for any help. -Trey

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  • TOTD #166: Using NoSQL database in your Java EE 6 Applications on GlassFish - MongoDB for now!

    - by arungupta
    The Java EE 6 platform includes Java Persistence API to work with RDBMS. The JPA specification defines a comprehensive API that includes, but not restricted to, how a database table can be mapped to a POJO and vice versa, provides mechanisms how a PersistenceContext can be injected in a @Stateless bean and then be used for performing different operations on the database table and write typesafe queries. There are several well known advantages of RDBMS but the NoSQL movement has gained traction over past couple of years. The NoSQL databases are not intended to be a replacement for the mainstream RDBMS. As Philosophy of NoSQL explains, NoSQL database was designed for casual use where all the features typically provided by an RDBMS are not required. The name "NoSQL" is more of a category of databases that is more known for what it is not rather than what it is. The basic principles of NoSQL database are: No need to have a pre-defined schema and that makes them a schema-less database. Addition of new properties to existing objects is easy and does not require ALTER TABLE. The unstructured data gives flexibility to change the format of data any time without downtime or reduced service levels. Also there are no joins happening on the server because there is no structure and thus no relation between them. Scalability and performance is more important than the entire set of functionality typically provided by an RDBMS. This set of databases provide eventual consistency and/or transactions restricted to single items but more focus on CRUD. Not be restricted to SQL to access the information stored in the backing database. Designed to scale-out (horizontal) instead of scale-up (vertical). This is important knowing that databases, and everything else as well, is moving into the cloud. RBDMS can scale-out using sharding but requires complex management and not for the faint of heart. Unlike RBDMS which require a separate caching tier, most of the NoSQL databases comes with integrated caching. Designed for less management and simpler data models lead to lower administration as well. There are primarily three types of NoSQL databases: Key-Value stores (e.g. Cassandra and Riak) Document databases (MongoDB or CouchDB) Graph databases (Neo4J) You may think NoSQL is panacea but as I mentioned above they are not meant to replace the mainstream databases and here is why: RDBMS have been around for many years, very stable, and functionally rich. This is something CIOs and CTOs can bet their money on without much worry. There is a reason 98% of Fortune 100 companies run Oracle :-) NoSQL is cutting edge, brings excitement to developers, but enterprises are cautious about them. Commercial databases like Oracle are well supported by the backing enterprises in terms of providing support resources on a global scale. There is a full ecosystem built around these commercial databases providing training, performance tuning, architecture guidance, and everything else. NoSQL is fairly new and typically backed by a single company not able to meet the scale of these big enterprises. NoSQL databases are good for CRUDing operations but business intelligence is extremely important for enterprises to stay competitive. RDBMS provide extensive tooling to generate this data but that was not the original intention of NoSQL databases and is lacking in that area. Generating any meaningful information other than CRUDing require extensive programming. Not suited for complex transactions such as banking systems or other highly transactional applications requiring 2-phase commit. SQL cannot be used with NoSQL databases and writing simple queries can be involving. Enough talking, lets take a look at some code. This blog has published multiple blogs on how to access a RDBMS using JPA in a Java EE 6 application. This Tip Of The Day (TOTD) will show you can use MongoDB (a document-oriented database) with a typical 3-tier Java EE 6 application. Lets get started! The complete source code of this project can be downloaded here. Download MongoDB for your platform from here (1.8.2 as of this writing) and start the server as: arun@ArunUbuntu:~/tools/mongodb-linux-x86_64-1.8.2/bin$./mongod./mongod --help for help and startup optionsSun Jun 26 20:41:11 [initandlisten] MongoDB starting : pid=11210port=27017 dbpath=/data/db/ 64-bit Sun Jun 26 20:41:11 [initandlisten] db version v1.8.2, pdfile version4.5Sun Jun 26 20:41:11 [initandlisten] git version:433bbaa14aaba6860da15bd4de8edf600f56501bSun Jun 26 20:41:11 [initandlisten] build sys info: Linuxbs-linux64.10gen.cc 2.6.21.7-2.ec2.v1.2.fc8xen #1 SMP Fri Nov 2017:48:28 EST 2009 x86_64 BOOST_LIB_VERSION=1_41Sun Jun 26 20:41:11 [initandlisten] waiting for connections on port 27017Sun Jun 26 20:41:11 [websvr] web admin interface listening on port 28017 The default directory for the database is /data/db and needs to be created as: sudo mkdir -p /data/db/sudo chown `id -u` /data/db You can specify a different directory using "--dbpath" option. Refer to Quickstart for your specific platform. Using NetBeans, create a Java EE 6 project and make sure to enable CDI and add JavaServer Faces framework. Download MongoDB Java Driver (2.6.3 of this writing) and add it to the project library by selecting "Properties", "LIbraries", "Add Library...", creating a new library by specifying the location of the JAR file, and adding the library to the created project. Edit the generated "index.xhtml" such that it looks like: <h1>Add a new movie</h1><h:form> Name: <h:inputText value="#{movie.name}" size="20"/><br/> Year: <h:inputText value="#{movie.year}" size="6"/><br/> Language: <h:inputText value="#{movie.language}" size="20"/><br/> <h:commandButton actionListener="#{movieSessionBean.createMovie}" action="show" title="Add" value="submit"/></h:form> This page has a simple HTML form with three text boxes and a submit button. The text boxes take name, year, and language of a movie and the submit button invokes the "createMovie" method of "movieSessionBean" and then render "show.xhtml". Create "show.xhtml" ("New" -> "Other..." -> "Other" -> "XHTML File") such that it looks like: <head> <title><h1>List of movies</h1></title> </head> <body> <h:form> <h:dataTable value="#{movieSessionBean.movies}" var="m" > <h:column><f:facet name="header">Name</f:facet>#{m.name}</h:column> <h:column><f:facet name="header">Year</f:facet>#{m.year}</h:column> <h:column><f:facet name="header">Language</f:facet>#{m.language}</h:column> </h:dataTable> </h:form> This page shows the name, year, and language of all movies stored in the database so far. The list of movies is returned by "movieSessionBean.movies" property. Now create the "Movie" class such that it looks like: import com.mongodb.BasicDBObject;import com.mongodb.BasicDBObject;import com.mongodb.DBObject;import javax.enterprise.inject.Model;import javax.validation.constraints.Size;/** * @author arun */@Modelpublic class Movie { @Size(min=1, max=20) private String name; @Size(min=1, max=20) private String language; private int year; // getters and setters for "name", "year", "language" public BasicDBObject toDBObject() { BasicDBObject doc = new BasicDBObject(); doc.put("name", name); doc.put("year", year); doc.put("language", language); return doc; } public static Movie fromDBObject(DBObject doc) { Movie m = new Movie(); m.name = (String)doc.get("name"); m.year = (int)doc.get("year"); m.language = (String)doc.get("language"); return m; } @Override public String toString() { return name + ", " + year + ", " + language; }} Other than the usual boilerplate code, the key methods here are "toDBObject" and "fromDBObject". These methods provide a conversion from "Movie" -> "DBObject" and vice versa. The "DBObject" is a MongoDB class that comes as part of the mongo-2.6.3.jar file and which we added to our project earlier.  The complete javadoc for 2.6.3 can be seen here. Notice, this class also uses Bean Validation constraints and will be honored by the JSF layer. Finally, create "MovieSessionBean" stateless EJB with all the business logic such that it looks like: package org.glassfish.samples;import com.mongodb.BasicDBObject;import com.mongodb.DB;import com.mongodb.DBCollection;import com.mongodb.DBCursor;import com.mongodb.DBObject;import com.mongodb.Mongo;import java.net.UnknownHostException;import java.util.ArrayList;import java.util.List;import javax.annotation.PostConstruct;import javax.ejb.Stateless;import javax.inject.Inject;import javax.inject.Named;/** * @author arun */@Stateless@Namedpublic class MovieSessionBean { @Inject Movie movie; DBCollection movieColl; @PostConstruct private void initDB() throws UnknownHostException { Mongo m = new Mongo(); DB db = m.getDB("movieDB"); movieColl = db.getCollection("movies"); if (movieColl == null) { movieColl = db.createCollection("movies", null); } } public void createMovie() { BasicDBObject doc = movie.toDBObject(); movieColl.insert(doc); } public List<Movie> getMovies() { List<Movie> movies = new ArrayList(); DBCursor cur = movieColl.find(); System.out.println("getMovies: Found " + cur.size() + " movie(s)"); for (DBObject dbo : cur.toArray()) { movies.add(Movie.fromDBObject(dbo)); } return movies; }} The database is initialized in @PostConstruct. Instead of a working with a database table, NoSQL databases work with a schema-less document. The "Movie" class is the document in our case and stored in the collection "movies". The collection allows us to perform query functions on all movies. The "getMovies" method invokes "find" method on the collection which is equivalent to the SQL query "select * from movies" and then returns a List<Movie>. Also notice that there is no "persistence.xml" in the project. Right-click and run the project to see the output as: Enter some values in the text box and click on enter to see the result as: If you reached here then you've successfully used MongoDB in your Java EE 6 application, congratulations! Some food for thought and further play ... SQL to MongoDB mapping shows mapping between traditional SQL -> Mongo query language. Tutorial shows fun things you can do with MongoDB. Try the interactive online shell  The cookbook provides common ways of using MongoDB In terms of this project, here are some tasks that can be tried: Encapsulate database management in a JPA persistence provider. Is it even worth it because the capabilities are going to be very different ? MongoDB uses "BSonObject" class for JSON representation, add @XmlRootElement on a POJO and how a compatible JSON representation can be generated. This will make the fromXXX and toXXX methods redundant.

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  • Is it bad practice to run Node.js and apache in parallel?

    - by Camil Staps
    I have an idea in mind and would like to know if that's the way to go for my end application. Think of my application as a social networking system in which I want to implement chat functionality. For that, I'd like to push data from the server to the client. I have heard I could use Node.js for that. In the meanwhile, I want a 'regular' system for posting status updates and such, for which I'd like to use PHP and an apache server. The only way I can think of is having Node.js and apache running parallel. But is that the way to go here? I'd think there would be a somewhat neater solution for this.

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  • NoSQL : MongoDB 2.2 est disponible, framework d'agrégation, meilleure gestion des clusters distribués et de l'accès concurrentiel

    NoSQL : MongoDB 2.2 est disponible Framework d'agrégation, meilleure gestion des clusters distribués et amélioration de l'accès concurrentiel 10Gen, l'entreprise derrière le SGBD populaire MongoDB, vient d'annoncer la dernière version de l'outil, à savoir la 2.2. Elle comporte des fonctionnalités anticipées dans la Developer Preview de la 2.1, mais adaptées à un environnement de production. [IMG]http://idelways.developpez.com/news/images/mongodb.png[/IMG]L'apport le plus important de cette version est un nouveau framework d'agrégation en temps réel idéal pour les opérations complexes d'analyse. Celui-ci permettra de récupérer et de manipuler les données dans MongoDB, san...

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  • Native packaging for JavaFX

    - by igor
    JavaFX 2.2 adds new packaging option for JavaFX applications, allowing you to package your application as a "native bundle". This gives your users a way to install and run your application without any external dependencies on a system JRE or FX SDK. I'd like to give you an overview of what is it, motivation behind it, and finally explain how to get started with it. Screenshots may give you some idea of user experience but first hand experience is always the best. Before we go into all of the boring details, here are few different flavors of Ensemble for you to try: exe, msi, dmg, rpm installers and zip of linux bundle for non-rpm aware systems. Alternatively, check out native packages for JFXtras 2. Whats wrong with existing deployment options? JavaFX 2 applications are easy to distribute as a standalone application or as an application deployed on the web (embedded in the web page or as link to launch application from the webpage). JavaFX packaging tools, such as ant tasks and javafxpackager utility, simplify the creation of deployment packages even further. Why add new deployment options? JavaFX applications have implicit dependency on the availability of Java and JavaFX runtimes, and while existing deployment methods provide a means to validate the system requirements are met -- and even guide user to perform required installation/upgrades -- they do not fully address all of the important scenarios. In particular, here are few examples: the user may not have admin permissions to install new system software if the application was certified to run in the specific environment (fixed version of Java and JavaFX) then it may be hard to ensure user has this environment due to an autoupdate of the system version of Java/JavaFX (to ensure they are secure). Potentially, other apps may have a requirement for a different JRE or FX version that your app is incompatible with. your distribution channel may disallow dependencies on external frameworks (e.g. Mac AppStore) What is a "native package" for JavaFX application? In short it is  A Wrapper for your JavaFX application that makes is into a platform-specific application bundle Each Bundle is self-contained and includes your application code and resources (same set as need to launch standalone application from jar) Java and JavaFX runtimes (private copies to be used by this application only) native application launcher  metadata (icons, etc.) No separate installation is needed for Java and JavaFX runtimes Can be distributed as .zip or packaged as platform-specific installer No application changes, the same jar app binaries can be deployed as a native bundle, double-clickable jar, applet, or web start app What is good about it: Easy deployment of your application on fresh systems, without admin permissions when using .zip or a user-level installer No-hassle compatibility.  Your application is using a private copy of Java and JavaFX. The developer (you!) controls when these are updated. Easily package your application for Mac AppStore (or Windows, or...) Process name of running application is named after your application (and not just java.exe)  Easily deploy your application using enterprise deployment tools (e.g. deploy as MSI) Support is built in into JDK 7u6 (that includes JavaFX 2.2) Is it a silver bullet for the deployment that other deployment options will be deprecated? No.  There are no plans to deprecate other deployment options supported by JavaFX, each approach addresses different needs. Deciding whether native packaging is a best way to deploy your application depends on your requirements. A few caveats to consider: "Download and run" user experienceUnlike web deployment, the user experience is not about "launch app from web". It is more of "download, install and run" process, and the user may need to go through additional steps to get application launched - e.g. accepting a browser security dialog or finding and launching the application installer from "downloads" folder. Larger download sizeIn general size of bundled application will be noticeably higher than size of unbundled app as a private copy of the JRE and JavaFX are included.  We're working to reduce the size through compression and customizable "trimming", but it will always be substantially larger than than an app that depends on a "system JRE". Bundle per target platformBundle formats are platform specific. Currently a native bundle can only be produced for the same system you are building on.  That is, if you want to deliver native app bundles on Windows, Linux and Mac you will have to build your project on all three platforms. Application updates are the responsibility of developerWeb deployed Java applications automatically download application updates from the web as soon as they are available. The Java Autoupdate mechanism takes care of updating the Java and JavaFX runtimes to latest secure version several times every year. There is no built in support for this in for bundled applications. It is possible to use 3rd party libraries (like Sparkle on Mac) to add autoupdate support at application level.  In a future version of JavaFX we may include built-in support for autoupdate (add yourself as watcher for RT-22211 if you are interested in this) Getting started with native bundles First, you need to get the latest JDK 7u6 beta build (build 14 or later is recommended). On Windows/Mac/Linux it comes with JavaFX 2.2 SDK as part of JDK installation and contains JavaFX packaging tools, including: bin/javafxpackagerCommand line utility to produce JavaFX packages. lib/ant-javafx.jar Set of ant tasks to produce JavaFX packages (most recommended way to deploy apps) For general information on how to use them refer to the Deploying JavaFX Application guide. Once you know how use these tools to package your JavaFX application for other deployment methods there are only a few minor tweaks necessary to produce native bundles: make sure java is used from JDK7u6 bundle you have installed adjust your PATH settings if needed  if you are using ant tasks add "nativeBundles=all" attribute to fx:deploy task if you are using javafxpackager pass "-native" option to deploy command or if you are using makeall command then it will try build native packages by default result bundles will be in the "bundles" folder next to other deployment artifacts Note that building some types of native packages (e.g. .exe or .msi) may require additional free 3rd party software to be installed and available on PATH. As of JDK 7u6 build 14 you could build following types of packages: Windows bundle image EXE Inno Setup 5 or later is required Result exe will perform user level installation (no admin permissions are required) At least one shortcut will be created (menu or desktop) Application will be launched at the end of install MSI WiX 3.0 or later is required Result MSI will perform user level installation (no admin permissions are required) At least one shortcut will be created (menu or desktop)  MacOS bundle image dmg (drag and drop) installer Linux bundle image rpm rpmbuild is required shortcut will be added to the programs menu If you are using Netbeans for producing the deployment packages then you will need to add custom build step to the build.xml to execute the fx:deploy task with native bundles enabled. Here is what we do for BrickBreaker sample: <target name="-post-jfx-deploy"> <fx:deploy width="${javafx.run.width}" height="${javafx.run.height}" nativeBundles="all" outdir="${basedir}/${dist.dir}" outfile="${application.title}"> <fx:application name="${application.title}" mainClass="${javafx.main.class}"> <fx:resources> <fx:fileset dir="${basedir}/${dist.dir}" includes="BrickBreaker.jar"/> </fx:resources> <info title="${application.title}" vendor="${application.vendor}"/> </fx:application> </fx:deploy> </target> This is pretty much regular use of fx:deploy task, the only special thing here is nativeBundles="all". Perhaps the easiest way to try building native bundles is to download the latest JavaFX samples bundle and build Ensemble, BrickBreaker or SwingInterop. Please give it a try and share your experience. We need your feedback! BTW, do not hesitate to file bugs and feature requests to JavaFX bug database! Wait! How can i ... This entry is not a comprehensive guide into native bundles, and we plan to post on this topic more. However, I am sure that once you play with native bundles you will have a lot of questions. We may not have all the answers, but please do not hesitate to ask! Knowing all of the questions is the first step to finding all of the answers.

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  • Wrapping my head around MongoDB, mongomapper and joins...

    - by cbmeeks
    I'm new to MongoDB and I've used RDBMS for years. Anyway, let's say I have the following collections: Realtors many :bookmarks key :name Houses key :address, String key :bathrooms, Integer Properties key :address, String key :landtype, String Bookmark key :notes I want a Realtor to be able to bookmark a House and/or a Property. Notice that Houses and Properties are stand-alone and have no idea about Realtors or Bookmarks. I want the Bookmark to be sort of like a "join table" in MySQL. The Houses/Properties come from a different source so they can't be modified. I would like to be able to do this in Rails: r = Realtor.first r.bookmarks would give me: House1 House2 PropertyABC PropertyOO1 etc... There will be thousands of Houses and Properties. I realize that this is what RDBMS were made for. But there are several reasons why I am using MongoDB so I would like to make this work. Any suggestions on how to do something like this would be appreciated. Thanks!

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  • node.js ./configure warnings

    - by microspino
    I'm trying to install node.js and I get this list of warnings when I run ./configer. I don't know which libraries/packages I miss on my Debian installation (Linux 2.6.32.6 ppc GNU/Linux on a Bubba2 sever) Checking for gnutls >= 2.5.0 : fail --- libeio --- Checking for pread(2) and pwrite(2) : fail Checking for sync_file_range(2) : fail --- libev --- Checking for header sys/inotify.h : not found Checking for header port.h : not found Checking for header sys/event.h : not found Checking for function kqueue : not found Checking for header sys/eventfd.h : not found Can you tell me what I need to install?

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  • Node app crashes after a while on micro EC2 instance even with supervisor

    - by Justin Meltzer
    I'm using supervisor to start my node.js application on a micro EC2 instance. However, the app only stays running for some time until it eventually shuts down. Not exactly sure how long the app stays running but I'm guessing for about a few hours or so. Sometimes less. My question is where on the remote server should I be looking in order to debug this kind of issue? I'm running an Amazon Linux AMI.

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  • Using MongoDB's map/reduce to "group by" two fields

    - by ibz
    I need something slightly more complex than the examples in the MongoDB docs and I can't seem to be able to wrap my head around it. Say I have a collection of objects of the form {date: "2010-10-10", type: "EVENT_TYPE_1", user_id: 123, ...} Now I want to get something similar to a SQL GROUP BY query, grouping over both date and type. That is, I want the number of events of each type in each day. Also, I'd like to make it unique by user_id, ie. if a user has more events in the same day, count it only once. I'm trying to do this with map/reduce. I do db.logs.mapReduce(function() { emit(this.type, 1); }, function(k, vals) { var total = 0; for (var i = 0; i < vals.length; i++) total += vals[i]; return total; }}) which nicely groups by type, but now, how can I group by date at the same time? Seems the key in emit() can't be an array (I thought about doing emit([this.date, this.type], 1)). Also, how can I ensure the per-user uniqueness? I'm just starting with MongoDB and I'm still having trouble grasping the basic concepts. Also, there is not much documentation available out there. Any help from more experienced users is appreciated. Thanks!

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  • Mongodb - how to deserialze when a property has an Interface return type

    - by Mark Kelly
    I'm attempting to avoid introducing any dependencies between my Data layer and client code that makes use of this layer, but am running into some problems when attempting to do this with Mongo (using the MongoRepository) MongoRepository shows examples where you create Types that reflect your data structure, and inherit Entity where required. Eg. [CollectionName("track")] public class Track : Entity { public string name { get; set; } public string hash { get; set; } public Artist artist { get; set; } public List<Publish> published {get; set;} public List<Occurence> occurence {get; set;} } In order to make use of these in my client code, I'd like to replace the Mongo-specific types with Interfaces, e.g: [CollectionName("track")] public class Track : Entity, ITrackEntity { public string name { get; set; } public string hash { get; set; } public IArtistEntity artist { get; set; } public List<IPublishEntity> published {get; set;} public List<IOccurenceEntity> occurence {get; set;} } However, the Mongo driver doesn't know how to treat these interfaces, and I understandably get the following error: An error occurred while deserializing the artist property of class sf.data.mongodb.entities.Track: No serializer found for type sf.data.IArtistEntity. --- MongoDB.Bson.BsonSerializationException: No serializer found for type sf.data.IArtistEntity. Does anyone have any suggestions about how I should approach this?

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