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  • Learning WPF GUI design

    - by Jon
    GUI's written using WPF seem to be closer to a Web 2.0 feel than older Winforms development has been; do you know of any good quality references online or books which give a general overview of how to design nice WPF applications? I saw this StackOverflow question where some GUI design books are mentioned, but am interested in information specifically for WPF. http://stackoverflow.com/questions/1193001/is-wpf-silverlight-design-worth-learning Thanks!

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  • Non-Relational Database Design

    - by Ian Varley
    I'm interested in hearing about design strategies you have used with non-relational "nosql" databases - that is, the (mostly new) class of data stores that don't use traditional relational design or SQL (such as Hypertable, CouchDB, SimpleDB, Google App Engine datastore, Voldemort, Cassandra, SQL Data Services, etc.). They're also often referred to as "key/value stores", and at base they act like giant distributed persistent hash tables. Specifically, I want to learn about the differences in conceptual data design with these new databases. What's easier, what's harder, what can't be done at all? Have you come up with alternate designs that work much better in the non-relational world? Have you hit your head against anything that seems impossible? Have you bridged the gap with any design patterns, e.g. to translate from one to the other? Do you even do explicit data models at all now (e.g. in UML) or have you chucked them entirely in favor of semi-structured / document-oriented data blobs? Do you miss any of the major extra services that RDBMSes provide, like relational integrity, arbitrarily complex transaction support, triggers, etc? I come from a SQL relational DB background, so normalization is in my blood. That said, I get the advantages of non-relational databases for simplicity and scaling, and my gut tells me that there has to be a richer overlap of design capabilities. What have you done? FYI, there have been StackOverflow discussions on similar topics here: the next generation of databases changing schemas to work with Google App Engine choosing a document-oriented database

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  • Using the WF rules engine without workflow in production - implementation experiences

    - by Josh E
    I'm designing an application for a type of case management system that has a big requirement for customizable, flexible business rules. I'm planning on using the WF Rules Engine without workflow (see: here, among other examples and such). One of the points my client brought up (justifiably so!) is whether there are extant examples of using the rules engine for a business rules engine without workflow. My question, of course is: Has anyone used the WF Rules engine sans workflow in a production application before, and what were your experiences?

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  • Design view disappeared from Interface Builder

    - by skywalker168
    All of a sudden, the visual design window disappeared from my Interface Builder. It is a regular UIView, has some UIImageView, UILabel, and UIButtons on it. When I open IB, I can see the document window (with File's Owner, First Responder and View in it), Library and Inspector, but the visual design window disappeared. Double click on "View" in the document window doesn't do anything. If I go to List mode, I can see all the components on the view, but just can no longer find the visual design window. All other XIB can open just fine, only this XIB lost its design window. First I thought maybe it was hidden somewhere on the screen. Tried all kinds of things, even rebooting the computer, but nothing helped. Can anyone help? Thanks in advance! By the way, I'm running SDK 3.2 Beta 3.

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  • Which Workflow Engine do you recommend?

    - by Glenn
    I am kicking around the idea of using a workflow engine on this upcoming project. We know that there is a lot of caveats with using a workflow engine and we have a lot of development experience in many platforms so we would be willing to let the choice of workflow engine take precedence over our favorite toolset or developer IDE. We are more interested in internal workflow (i.e. petri net for easily changeable ERP purposes without involving additional coder time) than external workflow (i.e. aggregating SOAP calls into a transaction aware, higher level SOA). Which workflow engine would you recommend? We have superficially looked at offerings by Oracle, Microsoft, and some open source stuff too. It's all very overwhelming so please respond only if you have real life experience with implementing internal workflow.

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  • Expression Engine using the Champagne Extension troubleshooting

    - by user975044
    I have an issue in Expression Engine using the Champagne Extension where it won't allow me to send out campaigns. This extension utilizes https://www.campaignmonitor.com/ api to send out mass emails. The Error I get is "HTML Content URL Required" when I try to send out campaigns form the back end of the Expression Engine Install. What could be causing this issue that relates to the expression engine install?

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  • Database design question

    - by Lijo
    Hi Team, I have an interesting database design problem that I formulated while travelling by a bus, coming back from my home. Design a normalized database for a bus ticketing system (not reservation system). In each trip, the conductor of the bus will give tickets to its passengers after collecting fare from them. Passengers travel from a various source places to various destination places. The system must be able to give a report of the places for which the number of passengers was more than 2. Suppose the stops for the bus are L1,L2, L3 and L4 Suppose passenger P1 travels from L1 to L4. P2 travels from L2 to L4. P3 travels from L3 to L4. The report should list only (L3-L4) for which it has more than 2 travelers. Can you please help me to solve the following problems 1) Design a normalized database 2) Write a query for the report 3) Is there any site that gives these kinds of interesting database design questions and answers? Thanks Lijo

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  • Ios development with design issues

    - by user3651999
    I don't know this question wether have been asked or not. But i research and found nothing.So my problem is i kinda new in IOS development. In android we can edit or customize design using UI and code(XML file). I prefer code.Does IOs have such file to edit/customize the design?Because I saw people always edit their design using the built-in UI rather than coding .I mean in design part not in function part.I would love using code any suggestion? Apperciate for any reply!

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  • Live Wallpaper Engine Abstraction

    - by user1459142
    I am trying to obtain an instance of my live wallpaper engine in another class, here is my code... In the other class: WallpaperEngine wpe = (WallpaperEngine) LiveWallpaperService.onCreateEngine(); In LiveWallpaperService: @Override public Engine onCreateEngine() { // TODO Auto-generated method stub return new WallpaperEngine(); } But when I refer to an object in my engine (i.e, "wpe.variable"), I get a NullPointerException and the wallpaper force closes.

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  • What is the Rule of Thumb on Exposing Encapsulated Class Methods

    - by javamonkey79
    Consider the following analogy: If we have a class: "Car" we might expect it to have an instance of "Engine" in it. As in: "The car HAS-A engine". Similarly, in the "Engine" class we would expect an instance of "Starting System" or "Cooling System" which each have their appropriate sub-components. By the nature of encapsulation, is it not true that the car "HAS-A" "radiator hose" in it as well as the engine? Therefore, is it appropriate OO to do something like this: public class Car { private Engine _engine; public Engine getEngine() { return _engine; } // is it ok to use 'convenience' methods of inner classes? // are the following 2 methods "wrong" from an OO point of view? public RadiatorHose getRadiatorHose() { return getCoolingSystem().getRadiatorHose(); } public CoolingSystem getCoolingSystem() { return _engine.getCoolingSystem(); } } public class Engine { private CoolingSystem _coolingSystem; public CoolingSystem getCoolingSystem() { return _coolingSystem; } } public class CoolingSystem { private RadiatorHose _radiatorHose; public RadiatorHose getRadiatorHose() { return _radiatorHose; } } public class RadiatorHose {//... }

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  • Fitting it together, database, reporting, applications in C#

    - by alvonellos
    Introduction Preamble I was hesitant to post this, since it's an application whose intricate details are defined elsewhere, and answers may not be helpful to others. Within the past few weeks (I was actually going to write a blog post about this after I finished) I've discovered that the barrier I'm encountering is one that's actually quite common for newer developers. This question is not so much about a specific thing as it is about piecing those things together. I've searched the internet far and wide, and found many tutorials on how to create applications that are kind of similar to what I'm looking for. I've also looked at hiring another, more experienced, developer to help me along, but all I've gotten are unqualified candidates that don't have the experience necessary and won't take care of the client or project like I will. I'd rather have the project never transpire than to release a solution that is half-baked. I've asked professors at my school, but they've not turned up answers to my question. I'm an experienced developer, and I've written many applications that are -- very abstractly -- close to what I'm doing, but my experiences from those applications aren't giving me enough leverage to solve this particular problem. I just hope that posting this article isn't a mistake for me to write. Project Description I have a project I'm working on for a client that is a rewrite of an application, originally written in Foxpro 2.6 by someone before me, that performs some analysis (which, sadly, I'm not allowed to disclose as per of my employment contract) on financial data. One day, after a long talk between the client and I -- where he intimately described his frustrations with all the bugs I've been hacking out of this code for 6 months now -- he told me to just rewrite it and gave me a month to write a good 1/8 of this 65k LOC Foxpro monstrosity. this 65k line of code foxpro monstrosity. It'll take me a good 3 - 6 months to rewrite this software (I know things the original programmer did not, like inheritance) going as I am right now, but I'm quickly discovering that I'm going to need to use databases. Prior to this contract I didn't even know about foxpro, and so I've had to learn foxpro on the fly, write procedures and make modifications to the database. I've actually come to like it, and this project would be rewritten in Foxpro if it were still a supported language, because over the past few months, I've come to like the features of Foxpro that make it so easy to develop data-driven applications. I once perfomed an experiment, comparing C# to Foxpro. What took me 45 minutes in C# took me two in Foxpro, and I knew C# prior to Foxpro. I was hoping to leverage the power of C#, but it intimidates me that in foxpro, you can have one line of code and be using a database. Prior to this, I have never written any serious database development from scratch. All the applications that I've written are in a different league. They are either completely data-naive or data-naive enough that I can get away with not using a database through serialization or by designing algorithms that work with the data in a manner that is stateless, so there is no need to worry about databases. I've come to realize, very quickly, that serialization and my efficacy with data structures has been my crutch all these years that's prevented me from adventuring into databases, and has consequently hindered my success in real-world programming. Sure, I've written some database stuff in Perl and Python, and I've done forms and worked with relational databases and tables, I'm a wizard in Access and Excel (seriously) and can do just about anything, but it just feels unnatural writing SQL code in another language... I don't mind writing SQL, and I don't It's that bridge between the database and the program code that drives me absolutely bonkers. I hope I'm not the only one to think this, but it bothers me that I have to create statements like the following string sSql = "SELECT * from tablename" When there's really no reason for that kind of unchecked language binding between two languages and two API's. Don't get my wrong, SQL is great, but I don't like the idea that, when executing commands on a SQL database, that one must intermix database and application software, and there's no database independence, which means that different versions of different databases can break code. This isn't very nice. The nicest thing about Foxpro is the cohesiveness between programming language and database. It's so easy, and Foxpro makes it easy, because the tool just fits the task. I can see why so many developers have created a career with this language, because it lowered the barrier of entry to data-driven applications that so many businesses need. It was wonderful. For my purposes today, with the demands and need for community support, extensibility, and language features, Foxpro isn't a solution that I feel would be the right tool for the job. I'm also worried about working too heavy with the database, because I've seen data-driven .NET applications have issues with database caches, running out of memory, and objects in the database not being collected. (Memory leaks) And OH the queries. Which one, how, and why? There are a plethora of different ways that a database can be setup, I think I counted 5 or 6 different kinds of database applications alone that I can chose from. That is a great mountain for me to climb when I don't even know where to begin when it comes to writing data-driven applications. The problem isn't that I don't know SQL or that I don't know C#. I know both and have worked with both extensively. It's making them work together that's the problem, and it's something I've never done in C# before. Reports The client likes paper. The data needs to be printed out in a format that is extensible, layered, and easy to use. I have never done reporting before, and so this is a bit of a problem. From the data source comes crystal reports, and so there's a dependency on the database, from what I understand. Code reuse A large part of the design decision that I've gone through so far is to break the task of writing a piece of this software into routines and modular DLL's and so forth such that much of the code can be reused. For example, when I setup this database, I want to be able to reuse the same database code over and over again. I also want to make sure that when the day comes that another developer is here, that he/she will be able to pick up just where I left off. The quicker I develop these applications, the better off I am. Tasks & Goals In my project, I need to write routines that apply algorithms and look for predefined patterns in financial data. Additionally, I need to simulate trading based on predefined algorithms and data. Then I need to prepare reports on that data. Additionally, I need to have a way to change the code base for this application quickly and effectively, without hacking together some band-aid solution for a problem that really needs a trauma ward. Special Considerations The solution must be fast, run quickly on existing hardware, and not be too much of a pain to maintain and write. I understand that anything I write I'm married to -- I'm responsible for the things that I write because my reputation and livelihood is dependent on it. Do I really need a database? What about performance? Performance was such a big issue that I hand wrote a data structure that is capable of performing 2 billion operations, using a total of 4 gigs of memory in under 1/4 of a second using the standard core two duo processor. I could not find a similar, pre-written data structure in C# to perform this task. What setup do I use in terms of database? What about reporting? I'd prefer to have PDF's generated, but I'd like to be able to visually sketch those reports and then just have a ReportFactory of some sort, that when I pass some variables in, it just does that data. About Me I'm a lone developer for a small business in this area. This is the first time I've done this and I've never had the breadth and depth of my knowledge tested. I'm incredibly frustrated with this project because I feel incredibly overwhelmed with the task at hand. I'm looking for that entry level point where I can draw a line and say "this is what I need to do" Conclusion I may have not been clear enough on my post. I'm still new to this whole thing, and I've been doing my best to contribute back to the community that I've leached so much knowledge from. I'd be glad to edit my post and add more information if possible. I'm looking for a big-picture solution or design process that helps me get off the ground in this world of data-driven applications, because I have a feeling that it's going to be concentric to my entire career as a programmer for some time. Specifically, if you didn't get it from the rest of the post (I may not have been clear enough) I really need some guidance as to where to go in terms of the design decisions for this project. Some things that'll be useful will be a pro/con list for the different kinds of database projects available in VS2010. I've tried, but generating that list has been as hard as solving the problem itself... If you could walk a developer writing a data-driven application for the first time in C#, how would you do that? Where would you point them to?

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  • How to "select file" with Python script? . Google App Engine . Python .

    - by draconisthe0ry
    I'm trying to create an online application for a python function i have created. in my script, i input the path of my file for the computer (input_path = '/users/user/desktop/input.txt') but i'm not sure how to go about this using Google App Engine . I have the choice between 3 templates: flask, django, and bottle . I really do believe this question is relevant for people transitioning from scripts to web-based applications. Do I need to incorporate GUI stuff from Tkinter or something? There has to be a way to simply select a file to use for the input path in an interactive way using python scripts

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  • Google Chrome custom search engine for secure Wikipedia

    - by gdejohn
    I have this custom search engine set up in Google Chrome: https://encrypted.google.com/search?q=site%3Aen.wikipedia.org+%s&btnI=745 It searches Google for site:en.wikipedia.org {query}, and the btnI=745 is for I'm Feeling Lucky, so it automatically redirects to the first result. I like this better than using Wikipedia's search function directly because it gives me very effective approximate string matching, so I can misspell my search, or leave a word out, or just search for some keywords, and I still get what I'm looking for right away. What I'd like is for it to use Wikipedia's secure gateway: https://secure.wikimedia.org/wikipedia/en/wiki/ It's easy enough to set up a custom search engine that uses the secure version of Wikipedia's search function directly, but I can't figure out how to correctly incorporate it into my version going through Google. Nothing I've tried works.

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  • How to choose NoSQL database engine?

    - by Poma
    We have a database with following specs: 30k records, 7mb in size 20 inserts/second 1000 updates/second 1000 range selects/second, by secondary index, approx 10 rows each needs at least one secondary index needs some mechanism to expire keys if they are not updated for 75 secs (can be done via programmatic garbage collector but will require additional 'last_update' index and will add some load) consistency is not required durability is not required db should be stored in memory For now we use Redis, but it does not have secondary index and it's keys index:foo:* is too slow. Membase also does not have secondary index (as far as I know). MongoDB and MySQL memory engine have table-level locks. What engine will fit our use case?

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  • What are developer's problems with helpful error messages?

    - by Moo-Juice
    It continue to astounds me that, in this day and age, products that have years of use under their belt, built by teams of professionals, still to this day - fail to provide helpful error messages to the user. In some cases, the addition of just a little piece of extra information could save a user hours of trouble. A program that generates an error, generated it for a reason. It has everything at its disposal to inform the user as much as it can, why something failed. And yet it seems that providing information to aid the user is a low-priority. I think this is a huge failing. One example is from SQL Server. When you try and restore a database that is in use, it quite rightly won't let you. SQL Server knows what processes and applications are accessing it. Why can't it include information about the process(es) that are using the database? I know not everyone passes an Applicatio_Name attribute on their connection string, but even a hint about the machine in question could be helpful. Another candidate, also SQL Server (and mySQL) is the lovely string or binary data would be truncated error message and equivalents. A lot of the time, a simple perusal of the SQL statement that was generated and the table shows which column is the culprit. This isn't always the case, and if the database engine picked up on the error, why can't it save us that time and just tells us which damned column it was? On this example, you could argue that there may be a performance hit to checking it and that this would impede the writer. Fine, I'll buy that. How about, once the database engine knows there is an error, it does a quick comparison after-the-fact, between values that were going to be stored, versus the column lengths. Then display that to the user. ASP.NET's horrid Table Adapters are also guilty. Queries can be executed and one can be given an error message saying that a constraint somewhere is being violated. Thanks for that. Time to compare my data model against the database, because the developers are too lazy to provide even a row number, or example data. (For the record, I'd never use this data-access method by choice, it's just a project I have inherited!). Whenever I throw an exception from my C# or C++ code, I provide everything I have at hand to the user. The decision has been made to throw it, so the more information I can give, the better. Why did my function throw an exception? What was passed in, and what was expected? It takes me just a little longer to put something meaningful in the body of an exception message. Hell, it does nothing but help me whilst I develop, because I know my code throws things that are meaningful. One could argue that complicated exception messages should not be displayed to the user. Whilst I disagree with that, it is an argument that can easily be appeased by having a different level of verbosity depending on your build. Even then, the users of ASP.NET and SQL Server are not your typical users, and would prefer something full of verbosity and yummy information because they can track down their problems faster. Why to developers think it is okay, in this day and age, to provide the bare minimum amount of information when an error occurs? It's 2011 guys, come on.

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  • Tips to Make Your Website Cell Phone Friendly

    - by Aditi
    Working on a new website design? or Redesigning your website? There is a lot more to consider now a days not just user experience, clean code, CSS etc. one of the important attribute one must not miss, which is making them mobile friendly! With the growing use of handhelds & unlimited data plans, people browse on their cellphones! and All come in different sizes! it is tough to make a website that would look great not just on a high resolution widescreen monitor/LCD, but also should look equally impressive on the low resolutions of cellphones. We are today going to discuss about such factors that can help you make a website Cellphone Friendly. Fluid Width Layouts As we start discussing about this, Most people speak of the Fluid Width Layouts as vital step in moving your website to be mobile friendly. Fluid width allows the width of your website stretch or shrink depending on the browser size. However, having a layout which flows with the width of the screen’s resolution is certainly convenient, more often than not the website was originally laid out for a desktop in mind. Compressing a fluid layout to 320 pixels can do some serious damage to layout, Thus some people strongly believe it is far better to have a mobile style sheet and lay out the content specifically for that screen and have more control on the display. The best thing to do is to detect the type of platform that is connected to your website and disabling or changing some tools and effects to make it look better if not perfect. Keep Your Web Pages Short length One must avoid long pages on their website, a lot of scroll makes it very non user friendly for people, especially on mobile devices this is a huge draw back because of the longer load time it takes to download the webpage. Everyone likes crisp & concise content such pages are easier to load & browse. This makes your website accessible across all platforms. Also try to keep shorter urls, if they have to type..save them from that much work especially if someone is using a cellphone with no QWERTY keyboard it can be tough. Usable Navigation & Search Unlike Desktops, your website’s Navigation won’t super work on a cellphone. Keep in mind the user experience for cellphone users as you design your Navigation. Try to keep your content centered as they do have difficulty in reading the webpage. I always look upto Google and their pages as available on mobile as a great example. Keeping a functional & very visible search bar helps mobile users navigate by searching. Understanding Clean Website Code : Evolved for Mobile Clean code is important when you consider the diversity out there for handheld devices. Some cell phones may only understand WAP. More capable phones may understand WAP2, which allows rendering websites with XHTML and CSS. Most mobiles won’t display tables, floats, frames, JavaScript, and dynamic menus. Most cellphone will not support cookies. Devices at the high end of the mobile market such as BlackBerry, Palm, or the upcoming iPhone are highly capable and support nearly as much as a standard computer..but masses still do not have such phones. You can use specific emulators to test your website on mobile devices. Make sure your color combinations provide good contrast between foreground and background colors, particularly for devices with fewer color options.

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  • Project structure: where to put business logic

    - by Mister Smith
    First of all, I'm not asking where does business logic belong. This has been asked before and most answers I've read agree in that it belongs in the model: Where to put business logic in MVC design? How much business logic should be allowed to exist in the controller layer? How accurate is "Business logic should be in a service, not in a model"? Why put the business logic in the model? What happens when I have multiple types of storage? However people disagree in the way this logic should be distributed across classes. There seem to exist three major currents of thought: Fat model with business logic inside entity classes. Anemic model and business logic in "Service" classes. It depends. I find all of them problematic. The first option is what most Fowlerites stick to. The problem with a fat model is that sometimes a business logic funtion is not only related to a class, and instead uses a bunch of other classes. If, for example, we are developing a web store, there should be a function that calcs an order's total. We could think of putting this function inside the Order class, but what actually happens is that the logic needs to use different classes, not only data contained in the Order class, but also in the User class, the Session class, and maybe the Tax class, Country class, or Giftcard, Payment, etc. Some of these classes could be composed inside the Order class, but some others not. Sorry if the example is not very good, but I hope you understand what I mean. Putting such a function inside the Order class would break the single responsibility principle, adding unnecesary dependences. The business logic would be scattered across entity classes, making it hard to find. The second option is the one I usually follow, but after many projects I'm still in doubt about how to name the class or classes holding the business logic. In my company we usually develop apps with offline capabilities. The user is able to perform entire transactions offline, so all validation and business rules should be implemented in the client, and then there's usually a background thread that syncs with the server. So we usually have the following classes/packages in every project: Data model (DTOs) Data Access Layer (Persistence) Web Services layer (Usually one class per WS, and one method per WS method). Now for the business logic, what is the standard approach? A single class holding all the logic? Multiple classes? (if so, what criteria is used to distribute the logic across them?). And how should we name them? FooManager? FooService? (I know the last one is common, but in our case it is bad naming because the WS layer usually has classes named FooWebService). The third option is probably the right one, but it is also devoid of any useful info. To sum up: I don't like the first approach, but I accept that I might have been unable to fully understand the Zen of it. So if you advocate for fat models as the only and universal solution you are welcome to post links explaining how to do it the right way. I'd like to know what is the standard design and naming conventions for the second approach in OO languages. Class names and package structure, in particular. It would also be helpful too if you could include links to Open Source projects showing how it is done. Thanks in advance.

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  • How to monetize and protect a engine's and its framework's copyrights and patents?

    - by Arthur Wulf White
    I created a game engine that handles: Rendering levels with 2d textured curved surfaces Collisions with curved surfaces Animationn paths on and navigation in 2d-sapce I have also made a framework for: Procedural organic level generation with round surfaces Level editing Light weight sprite design The engine and framework are written in AS3 and I am in the process of translating the code into HaXe to better support other platforms. I am also interested in adding Animated curved platforms More advanced level editing features Currently, I have a part time job and any time I spend on this engine is either taken out of my limited free time (I'm a student working to support myself through school) or out my time working at my job. I really believe this engine can make life much easier for people designing Tower Defence games, Shooters and and Platformers while also possibly improving their results. It could also support RTS, RPGs and racing games very well. It continains original algorithms that could be used for procedural generation of organic round and smooth levels. The algorithms I used are new and are not available in any other level editor I've seen. In order to constantly improve the Engine and have it tested thoroughly I think the best route is releasing it to the public. What are the best ways to benefit myself and others with my new framework? I want to have some lisence, allowing me to share the framework and still benefit from it. Any advice would be appreciated. This issue has been on my mind a lot this year. I am hoping to find a solution that will bring me some relief. I am thinking of designing three sample games, releasing them and starting a kickstarter, any advice and thoughts on the matter would be valuable. My goal is like Markus von Broady suggested, to get people involved in developing the engine and let people use it for games for either a symbolic fee or for free and charge for support. That or use some form of croud sourcing. Do I need to hire a lawyer to get some sort of legal document to protect my work?

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