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• Setter Validation can affect performance?

  - by TiagoBrenck

  Whitin a scenario where you use an ORM to map your entities to the DB, and you have setter validations (nullable, date lower than today validation, etc) every time the ORM get a result, it will pass into the setter to instance the object. If I have a grid that usually returns 500 records, I assume that for each record it passes on all validations. If my entity has 5 setter validations, than I have passed in 2.500 validations. Does those 2.500 validations will affect the performance? If was 15.000 validation, it will be different? In my opinion, and according to this answer (http://stackoverflow.com/questions/4893558/calling-setters-from-a-constructor/4893604#4893604), setter validation is usefull than constructors validation. Is there a way to avoid unecessary validation, since I am safe that the values I send to DB when saving the entity wont change until I edit it on my system?

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• Can't I just use all static methods?

  - by Reddy S R

  What's the difference between the two UpdateSubject methods below? I felt using static methods is better if you just want to operate on the entities. In which situations should I go with non-static methods? public class Subject { public int Id {get; set;} public string Name { get; set; } public static bool UpdateSubject(Subject subject) { //Do something and return result return true; } public bool UpdateSubject() { //Do something on 'this' and return result return true; } } I know I will be getting many kicks from the community for this really annoying question but I could not stop myself asking it. Does this become impractical when dealing with inheritance?

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• LSP vs OCP / Liskov Substitution VS Open Close

  - by Kolyunya

  I am trying to understand the SOLID principles of OOP and I've come to the conclusion that LSP and OCP have some similarities (if not to say more). the open/closed principle states "software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification". LSP in simple words states that any instance of Foo can be replaced with any instance of Bar which is derived from Foo and the program will work the same very way. I'm not a pro OOP programmer, but it seems to me that LSP is only possible if Bar, derived from Foo does not change anything in it but only extends it. That means that in particular program LSP is true only when OCP is true and OCP is true only if LSP is true. That means that they are equal. Correct me if I'm wrong. I really want to understand these ideas. Great thanks for an answer.

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• Books or help on OO Analysis

  - by Pat

  I have this course where we learn about the domain model, use cases, contracts and eventually leap into class diagrams and sequence diagrams to define good software classes. I just had an exam and I got trashed, but part of the reason is we barely have any practical material, I spent at least two good months without drawing a single class diagram by myself from a case study. I'm not here to blame the system or the class I'm in, I'm just wondering if people have some exercise-style books that either provide domain models with glossaries, system sequence diagrams and ask you to use GRASP to make software classes? I could really use some alone-time practicing going from analysis to conception of software entities. I'm almost done with Larman's book called "Applying UML and Patterns An Introduction to Object-Oriented Analysis and Design and Iterative Development, Third Edition". It's a good book, but I'm not doing anything by myself since it doesn't come with exercises. Thanks.

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• Installing, Configuring, and Testing WebLogic Server 12c Developer Zip Distribution in NetBeans

  - by JuergenKress

  This tutorial covers how to install Oracle WebLogic Server 12c (12.1.1) developer zip file distribution on Windows and configure it as a Java EE Application Server in NetBeans. Also covers how to test the WebLogic Server installation by deploying a Web application based on JSF and JPA entities. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. BlogTwitterLinkedInMixForumWiki Technorati Tags: WebLogic installation,Netbeans,Developer zip,WebLogic Community,Oracle,OPN,Jürgen Kress

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• Should a programmer take writing lessons to enhance code expressiveness?

  - by Jose Faeti

  Given that programmers are authors and write code to express abstract thoughts and concepts, and good code should be read by other programmers without difficulties and misunderstandings, should a programmer take writing lessons to write better code? Abstracting concepts and real world problems/entities is an important part of writing good code, and a good mastery of the language used for coding should allow the programmer to express his thoughts more easily, or in a better way. Besides, when trying to write or rewrite some code to make it better, much time can be spent in deciding the names for functions, variables or data structures. I think this could also help to avoid writing code with more than one meaning, often cause of misunderstanding between different programmers. Code should always express clearly its function unambiguously.

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• Database-as-a-Service on Exadata Cloud

  - by Gagan Chawla

  Note – Oracle Enterprise Manager 12c DBaaS is platform agnostic and is designed to work on Exadata/non-Exadata, physical/virtual, Oracle/non Oracle platforms and it’s not a mandatory requirement to use Exadata as the base platform. Database-as-a-Service (DBaaS) is an important trend these days and the top business drivers motivating customers towards private database cloud model include constant pressure to reduce IT Costs and Complexity, and also to be able to improve Agility and Quality of Service. The first step many enterprises take in their journey towards cloud computing is to move to a consolidated and standardized environment and Exadata being already a proven best-in-class popular consolidation platform, we are seeing now more and more customers starting to evolve from Exadata based platform into an agile self service driven private database cloud using Oracle Enterprise Manager 12c. Together Exadata Database Machine and Enterprise Manager 12c provides industry’s most comprehensive and integrated solution to transform from a typical silo’ed environment into enterprise class database cloud with self service, rapid elasticity and pay-per-use capabilities.   In today’s post, I’ll list down the important steps to enable DBaaS on Exadata using Enterprise Manager 12c. These steps are chalked down based on a recent DBaaS implementation from a real customer engagement - Project Planning - First step involves defining the scope of implementation, mapping functional requirements and objectives to use cases, defining high availability, network, security requirements, and delivering the project plan. In a Cloud project you plan around technology, business and processes all together so ensure you engage your actual end users and stakeholders early on in the project right from the scoping and planning stage. Setup your EM 12c Cloud Control Site – Once the project plan approval and sign off from stakeholders is achieved, refer to EM 12c Install guide and these are some important tips to follow during the site setup phase - Review the new EM 12c Sizing paper before you get started with install Cloud, Chargeback and Trending, Exadata plug ins should be selected to deploy during install Refer to EM 12c Administrator’s guide for High Availability, Security, Network/Firewall best practices and options Your management and managed infrastructure should not be combined i.e. EM 12c repository should not be hosted on same Exadata where target Database Cloud is to be setup Setup Roles and Users – Cloud Administrator (EM_CLOUD_ADMINISTRATOR), Self Service Administrator (EM_SSA_ADMINISTRATOR), Self Service User (EM_SSA_USER) are the important roles required for cloud lifecycle management. Roles and users are managed by Super Administrator via Setup menu –> Security option. For Self Service/SSA users custom role(s) based on EM_SSA_USER should be created and EM_USER, PUBLIC roles should be revoked during SSA user account creation. Configure Software Library – Cloud Administrator logs in and in this step configures software library via Enterprise menu –> provisioning and patching option and the storage location is OMS shared filesystem. Software Library is the centralized repository that stores all software entities and is often termed as ‘local store’. Setup Self Update – Self Update is one of the most innovative and cool new features in EM 12c framework. Self update can be accessed via Setup -> Extensibility option by Super Administrator and is the unified delivery mechanism to get all new and updated entities (Agent software, plug ins, connectors, gold images, provisioning bundles etc) in EM 12c. Deploy Agents on all Compute nodes, and discover Exadata targets – Refer to Exadata discovery cookbook for detailed walkthrough to ensure successful discovery of Exadata targets. Configure Privilege Delegation Settings – This step involves deployment of privilege setting template on all the nodes by Super Administrator via Setup menu -> Security option with the option to define whether to use sudo or powerbroker for all provisioning and patching operations. Provision Grid Infrastructure with RAC Database on Compute Nodes – Software is provisioned in this step via a provisioning profile using EM 12c database provisioning. In case of Exadata, Grid Infrastructure and RAC Database software is already deployed on compute nodes via OneCommand from Oracle, so SSA Administrator just needs to discover Oracle Homes and Listener as EM targets. Databases will be created as and when users request for databases from cloud. Customize Create Database Deployment Procedure – the actual database creation steps are "templatized" in this step by Self Service Administrator and the newly saved deployment procedure will be used during service template creation in next step. This is an important step and make sure you have locked all the required variables marked as locked as ‘Y’ in this table. Setup Self Service Portal – This step involves setting up of zones, user quotas, service templates, chargeback plan. The SSA portal is setup by Self Service Administrator via Setup menu -> Cloud -> Database option and following guided workflow. Refer to DBaaS cookbook for details. You also have an option to customize SSA login page via steps documented in EM 12c Cloud Administrator’s guide Final Checks – Define and document process guidelines for SSA users and administrators. Get your SSA users trained on Self Service Portal features and overall DBaaS model and SSA administrators should be familiar with Self Service Portal setup pieces, EM 12c database lifecycle management capabilities and overall EM 12c monitoring framework. GO LIVE – Announce rollout of Database-as-a-Service to your SSA users. Users can login to the Self Service Portal and request/monitor/view their databases in Exadata based database cloud. Congratulations! You just delivered a successful database cloud implementation project! In future posts, we will cover these additional useful topics around database cloud – DBaaS Implementation tips and tricks – right from setup to self service to managing the cloud lifecycle ‘How to’ enable real production databases copies in DBaaS with rapid provisioning in database cloud Case study of a customer who recently achieved success with their transformational journey from traditional silo’ed environment on to Exadata based database cloud using Enterprise Manager 12c. More Information – Podcast on Database as a Service using Oracle Enterprise Manager 12c Oracle Enterprise Manager 12c Installation and Administration guide, Cloud Administration guide DBaaS Cookbook Exadata Discovery Cookbook Screenwatch: Private Database Cloud: Set Up the Cloud Self-Service Portal Screenwatch: Private Database Cloud: Use the Cloud Self-Service Portal Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Newsletter

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• 45 minutes to talk about C# [closed]

  - by Philip

  I have the opportunity to give a 45 minute talk on C# in the theory of programming languages class I'm taking. The college teaches Java almost exclusively, so that's what all the students are most familiar with. (There's a little C, assembly, Prolog and LISP as well.) I decide what to talk about. It seems to me the best approach is to focus on a few of the big, obvious differences between C# and Java. I don't intend it to be a recommendation to use C# -- there are reasons to use each, mostly because of their ecosystems. So I want to focus on C# as a language. I don't want to go too fast and end up listing a whole bunch of features without showing their usefulness. My current plan is this: Functions as first class objects. This is, in my opinion, one of the biggest differences between C# and Java. The professor briefly mentioned this notion and showed a LISP example, but many of the students have probably never used it. I can show real world examples where it's made my code more readable. Lambda expressions as concise syntax for anonymous functions. Obviously with examples to show how this is useful. The real hit-home examples will be at the end when it's combined with the rest. I don't see an advantage to first showing the old delegate syntax and then replacing it with lambdas -- most of us won't have ever seen delegates anyway so it would just be confusing. The yield keyword and how it's different from returning an array. I have the impression that a lot of C# developers aren't familiar with how to use this. It will likely be very foreign to Java developers. I have some examples from my own work where it was really useful, such as iterating over a tree traversal, or iterating over neighbors in a graph where the neighbors aren't stored in memory. In both cases, doing it in Java would likely mean returning a complete list -- with yield I can stop iterating if I find what I want early on, without using memory for superfluous lists or arrays. Extension methods as a way to write implementation on interfaces. We'll all be familiar with how interfaces don't allow method implementation, and how this leads to code duplication. I'll show a specific example of this and how the extension method can solve the problem. Demonstrate how the above can be combined by implementing some simple Linq methods and using them. Where, Select, First, maybe more depending on how much time is left. Ideas on which ones might 'hit home' the best? There are other things I could talk about such as generics, value types, properties and more. I haven't yet though of good ways to incorporate these. In the case of generics and value types, the advantages might not be obvious or as relevant. Properties are obviously useful, particularly since we're taught strict JavaBeans here, but I don't know if I could integrate it with the "path to Linq" discussion above without it feeling tacked on. So I'm looking for thoughts on how to talk about C#, and what to talk about. Even minor details. I'm sure there are more experienced C# developers than me here who have good insight about what's really important in the language, and what would miss the point.

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• Would a model like this translate well to a document or graph database?

  - by Eric

  I'm trying to understand what types of models that I have traditionally persisted relationally would translate well to some kind of NoSQL database. Suppose I have a model with the following relationships: Product 1-----0..N Order Customer 1-----0..N Order And suppose I need to frequently query things like All Orders, All Products, All Customers, All Orders for Given Customer, All Orders for Given Product. My feeling is that this kind of model would not denormalize cleanly - If I had Product and Customer documents with embedded Orders, both documents would have duplicate orders. So I think I'd need separate documents for all three entities. Does a characteristic like this typically indicate that a document database is not well suited for a given model? Generally speaking, would a document database perform as well as a relational database in this kind of situation? I know very little about graph databases, but I understand that a graph database handles relationships more performantly than a document database - would a graph database be suited for this kind of model?

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• How often do CPUs make calculation errors?

  - by veryfoolish

  In Dijkstra's Notes on Structured Programming he talks a lot about the provability of computer programs as abstract entities. As a corollary, he remarks how testing isn't enough. E.g., he points out the fact that it would be impossible to test a multiplication function f(x,y) = x*y for any large values of x and y across the entire ranges of x and y. My question concerns his misc. remarks on "lousy hardware". I know the essay was written in the 1970s when computer hardware was less reliable, but computers still aren't perfect, so they must make calculation mistakes sometimes. Does anybody know how often this happens or if there are any statistics on this?

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• Appropriate level of granularity for component-based architecture

  - by Jon Purdy

  I'm working on a game with a component-based architecture. An Entity owns a set of Component instances, each of which has a set of Slot instances with which to store, send, and receive values. Factory functions such as Player produce entities with the required components and slot connections. I'm trying to determine the best level of granularity for components. For example, right now Position, Velocity, and Acceleration are all separate components, connected in series. Velocity and Acceleration could easily be rewritten into a uniform Delta component, or Position, Velocity, and Acceleration could be combined alongside such components as Friction and Gravity into a monolithic Physics component. Should a component have the smallest responsibility possible (at the cost of lots of interconnectivity) or should related components be combined into monolithic ones (at the cost of flexibility)? I'm leaning toward the former, but I could use a second opinion.

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• EclipseLink Moxy Provider for JAX-RS and JAX-WS

  - by arungupta

  EclipseLink MOXy is a JAXB provider bundled in GlassFish 3.1.2. In addition to JAXB RI, it provides XPath Based Mapping, better support for JPA entities, native JSON binding and many other features. Learn more about MOXy and JAXB examples on their wiki. Blaise blogged about how MOXy can be leveraged to create a JAX-WS service.You just need to provide data-binding attribute in sun-jaxws.xml and then all the XPath-based mapping can be specified on JAXB beans. MOXy can also be used as JAX-RS JSON provider on server-side and client-side. How are you using MOXy in your applications ?

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• America The Vulnerable

  - by Naresh Persaud

  At the Executive Edge this week, Joel Brenner shared his perspective on the state of cyber-security. Today our most critical military and corporate secrets are under attack. In his presentation, Joel shared his perspective on how organizations can can better prepare for the changing security climate. The amount of state sponsored espionage has highlighted weaknesses in our national security infrastructure. The Internet was primarily intended to provide a means of collaboration for non-commercial entities. Today it is the backbone of our digital commerce and digital experience and it was not designed to secure the activities and data we share today.  Check out "America The Vulnerable" and learn more. 

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• Create named criteria in EJB Data control

  - by shantala.sankeshwar

  This article gives the detailed steps on creating named criteria in EJB Data control.Note that this feature is available in Jdev version 11.1.2.0.0Use Case DescriptionSuppose we have defined an EJB Entity Object & we would like to filter the Entity object based on some criteria,then this filtering can be achieved by creating named criteria in EJB Data Control.Implementation stepsLet us suppose that we have created Java EE Web Application with Entities from Emp table Create session bean,generate data control for the same Edit empFindAll in DataControls.dcx fileCreate simple Named Criteria: deptno>=20Create on '+' icon to create Named Criteria:Refresh the Data Controls & create a new jspx page.Drop EmpCriteria as ADF Query Panel with TableRun the page,click on search button & we will see that Emp table shows filtered records

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• EclipseLink 2.4 Released: RESTful Persistence, Tenant Isolation, NoSQL, and JSON

  - by arungupta

  EclipseLink 2.4 is released as part of Eclipse Juno release train. In addition to providing the Reference Implementation for JPA 2.0, the key features in the release are: RESTful Persistence - Expose Java Persistence units over REST using either JSON or XML Tenant Isolation - Manage entities for multiple tenants in the same application NoSQL - NoSQL support for MongoDB and Oracle NoSQL JSON - Marshaling and unmarshaling of JSON object Here is the complete list of bugs fixed in this release. The landing page provide the complete list of documentation and examples. Read Doug Clarke's blog for a color commentary as well. This release is already integrated in the latest GlassFish 4.0 promoted build. Try the functionality and give us feedback at GlassFish Forum or EclipseLink Forum.

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• Which programming language could I use for Natural Language Processing to extract clinical words?

  - by MACEE

  I am going to do entity extraction (like Named Entity Recognition) from clinical free text (unstructured raw text such as discharge summaries) and these entities could be any medical problem, medical tests or treatments. I am going to use one of i2b2 datasets (https://www.i2b2.org/) if case you are familiar with that. I am new to the NLP(Natural Language Processing) field and I need a programming language to support NLP tasks and also easily connect to the available libraries of machine learning algorithms like CRF. I don't know much java and I heard about Python, Perl and Scala but I am not sure which one would be the best option for this task?

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• Biome Transition in a Grid & Borderless World

  - by API-Beast

  I have a universe: a list of "Systems", each with their own center, type and radius. A small part of such a universe could look like this: Systems: Can be very close to a different system, e.g. overlap Can be inside another, much bigger system Can be very far away from any other systems Spawn system specific entities and particles inside the system radius Have some properties like background color So far so good. However, the player can fly around freely, inside and outside of systems, in real time. How do I interpolate and determine things like the background color now, depending on camera position? E.g. if you are halfway between a green and a red system you should see a background halfway between red and green, or if you are inside a lilac system near the center and at the border of a green system you should get a mostly lilac background etc.

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• Keep user and user profile in different tables?

  - by Andrey

  I have seen in a couple of projects that developers prefer to keep essential user info in one table (email/login, password hash, screen name) and rest of the non essential user profile in another (creation date, country, etc). By non-essential I mean that this data is needed only occasionally. Obvious benefit is that if you are using ORM querying less fields is obviously good. But then you can have two entities mapped to same table and this will save you from querying stuff you don't need (while being more convenient). Does anybody know any other advantage of keeping these things in two tables?

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• Custom extensible file format for 2d tiled maps

  - by Christian Ivicevic

  I have implemented much of my game logic right now, but still create my maps with nasty for-loops on-the-fly to be able to work with something. Now I wanted to move on and to do some research on how to (un)serialize this data. (I do not search for a map editor - I am speaking of the map file itself) For now I am looking for suggestions and resources, how to implement a custom file format for my maps which should provide the following functionality (based on MoSCoW method): Must have Extensibility and backward compatibility Handling of different layers Metadata on whether a tile is solid or can be passed through Special serialization of entities/triggers with associated properties/metadata Could have Some kind of inclusion of the tileset to prevent having scattered files/tilesets I am developing with C++ (using SDL) and targetting only Windows. Any useful help, tips, suggestions, ... would be appreciated!

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• Design patterns for effects between actors and technology

  - by changelog

  I'm working on my first game, and taking the opportunity to brush up my C++ (I want to make as much of it as portable as I can.) Whilst working on the technology tree and how it affects actors (spaceships, planets, crew, buildings, etc) I can't find a pattern that decouples these entities enough to feel like a clean approach. Just as an idea, here's the type of effects these actors can have on one another (and techs too) An engineer inside a spaceship boosts its shield A hero in a spaceship in a fleet increases morale A technology improves spaceships' travel distance A building in a planet improves its production The best I can come up with is the Observer pattern, and basically manage it more or less manually (when a crew member enters a spaceship, fire the event; when a new building is built in a planet, fire the event, etc etc.) but it seems to be too tightly coupled to me. I would love to get some ideas about how to approach this better.

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• Making more complicated systems(entity-component-system model question)

  - by winch

  I'm using a model where entities are collections of components and components are just data. All the logic goes into systems which operate on components. Making basic systems(for Rendering and handling collision) was easy. But how do I do more compilcated systems? For example, in a CollisionSystem I can check if entity A collides with entity B. I have this code in CollisionSystem for checking if B damages A: if(collides(a, b)) { HealthComponent* hc = a->get<HealthComponent(); hc.reduceHealth(b->get<DamageComponent>()->getDamage()); But I feel that this code shouldn't belong to Collision system. Where should code like this be and which additional systems should I create to make this code generic?

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• How to model interentity membership in entity-component architecture?

  - by croxis

  I'm falling in love with simple grace of entity-component design, although I still have issues breaking from MVC and OOP practices. Some of my game entities have membership relationships with each other (ex: a player is a member of a city, a city is a member of a nation), and I am unsure on the best way to implement it. My initial reaction is to have a a MemberOfCity component that points to the appropriate city component, but components are suppose to have no references to each other. My other option is to have a System do it, but that would require the system to persist data outside of a component. Is there a clean way to do this in an entity-component design, or am I trying to use a hammer on a screw and should use a hybrid/another approach?

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• Interpolating between two networked states?

  - by Vaughan Hilts

  I have many entities on the client side that are simulated (their velocities are added to their positions on a per frame basis) and I let them dead reckon themselves. They send updates about where they were last seen and their velocity changes. This works great and other players see this work find. However, after a while these players begin to desync after some time. This is because of latency. I'd like to know how I can interpolate between states so they appear to be in the correct position. I know where the player was LAST seen and their current velocity but interpolating to the last seen state causes the player to actually move -backwards-. I could not use velocity at all for other clients and simply 'lerp' them towards the appropriate direction but I feel this would cause jaggy movement. What are the alternatives?

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• How to perform efficient 2D picking in HTML5?

  - by jSepia

  I'm currently using an R-Tree for both picking and collision testing. Each entity on screen has a bounding box for collisions and a separate one for picking. Since entities may change position very frequently, both trees must be updated/reordered once per frame. While this is very efficient for collisions, because the tree is used in hundreds of collision queries every frame, I'm finding it too costly for picking, because it only gets queried when the user clicks, thus leading to a lot of wasted tree updates. What would be a more efficient way to implement picking without as much overhead?

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• Using an open source non-free license

  - by wagglepoons

  Are there any projects/products out there that use an open source license that basically says "free for small companies" and "cost money for larger companies" in addition to "make modifications available"? (And are there any standard licenses with such a wording?) If I were to release a project under such a license, would it be automatically shunned by every developer on the face of the earth, or, assuming it is actually a useful project, does it have a fair chance at getting contributions from Joe Programmer? The second part of this question can easily become subjective, but any well argued point of view will be highly appreciated. For example, do dual licensed projects made by commercial entities have success with the open source communities?

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