I'd like to know what are the best practices when creanting a complex and big flex modular application? particularly concercing internationalization, performance, remoting(service), skinning, caching, logging.
How to use theses common resources?
Imagine that many developers will work on the same project, but on different 'small' modules each, and they don't have to know how the entire application works. So every developer will create and compile his/her module (swf), and I'll just have to put these swf in their appropriate folders.
What do you think about this approach:
create a common library : myAppLibrary, which manage languages, services, caching, logging, debuging.. For example this library can have these functions : translate(str:String):String, callAmfService(class:String,methode:string,...params), loadCache(cacheKey:String):Object, etc
require that every module(developer) should use this library when handling languages, services etc. Eg within a module, a developper can do : langSingleton::getInstance()->translate('somestring') for example
make modules communicate by events
(sorry if my english's not clear)
Thanks
Related
I am trying to implement modular design in an asp.net project dividing the application into different modules like HR, Inventory Management System etc. Since I am trying to keep different modules independent of each other, I separated these modules in such a way that each module is a separate Visual studio solution having UI, BLL, DAL and even a separate database schema.
Up till now I thought this as a common practice for developing Management systems and ERPs but I am searching the web for last three days but hardly found any help full stuff regarding developing modular applications. Most of what I found is mere theory explaining the concepts of cohesion and coupling but not real world scenarios. So I wonder
Is it the right approach of separating modules?
How the real world modular applications are developed?
How should the different modules communicate with each other yet they stay independent of each other.
I think there should be a core application which makes use of these modules, how should the core application communicate with these modules?
There is some data, entities , objects which are common to each module, should I put them in the core modules in order for other modules to use them (I think this will make the modules coupled to core) or should every modules maintain its own copy of data + define those object, (which I think voilates DRY)
Any thoughts, links are warmly welcome.
This is a personal opinion and is debatable.
I separated these modules in such a way that each module is a separate Visual studio solution having UI, BLL, DAL and even a separate database schema.
Sounds like a total overkill. Abstraction over abstraction makes your application pain in the neck to maintain, support, and enhance. Is it that large that you need to separate modules into separate solutions?
Is it the right approach of separating modules?
No, I think it is a total over-engineering. I would suggest using projects to separate modules. And not separate solutions. The problem with solution is that it will require external dependencies management tool, which requires a lot of effort to bring in and later maintain.
How the real world modular applications are developed?
Using abstraction (interfaces and abstract classes) and separate projects.
How should the different modules communicate with each other yet they stay independent of each other.
By using interfaces, DI, IOC, TDD
I think there should be a core application which makes use of these modules, how should the core application communicate with these modules?
Core does not communicate with modules. In fact it should ideally not depend on any other project/library. This makes it simple to reference and use in large solutions.
There is some data, entities , objects which are common to each module, should I put them in the core modules in order for other modules to use them (I think this will make the modules coupled to core) or should every modules maintain its own copy of data + define those object, (which I think voilates DRY)
I would highly recommend using a single copy from the Core project. See this questions for details of why.
This is one of those topics that is entirely subjective for the most part, but you may wish to consider a SOA (Service Oriented Architecture).
Using SOA, you can define a service (for this example, I'll stick to web services, though other service types exist depending on requirements) for each business area - an HR web service, a projects web service, a finance web service and so forth.
You can then bring all these together with a front end system that will communicate with and utilise these services, that would normally be your core application, though depending on your needs and requirements you may opt for multiple front end systems.
For the front end system I would recommend using ASP.NET MVC which has the concept of areas and will let you separate the front end into specific areas - an HR area, a projects area, a finance area and so forth that will contain the models and views for each specific area.
Doing this will let you build in a modular manner, you can build your first web service, say, the HR web service, that has methods for getting relevant HR data and so forth, and then build the HR area of your MVC application. Expanding then simply depends on building the web service, and creating the front end in the MVC application. There is nothing stopping say the HR area then accessing the finance web service if it needs finance information, but it still keeps everything in distinct independent modules.
Using this method can also be helpful in aiding future interoperability - it may be that other systems in the company will find it useful to interact with certain web services. For example, in a previous role it was useful for the companies engineering software to integrate with the projects team web service as it allowed for engineering related information to be linked to it's related project.
If the system grows in terms of resource requirements it should also be fairly scalable as it is trivial to say, offload the projects web service to another service if it starts eating a lot of system resources. It also allows you to switch modules out if need be - if you ever decided to move to say, a Linux/Java platform, you could trivially move by porting module by module with no real interruption of the overall system.
But of course, as I say, this is simply one such option and much of it depends on the specifics of your circumstances.
It is too late to answer but it seems interesting.
Since I am trying to keep different modules independent of each other, I separated these modules in such a way that each module is a separate Visual studio solution having UI, BLL, DAL and even a separate database schema.
It depends on your scale of application. If you create a very small-simple application with a little functionality, then it is safe to has a combined assembly. Or if you want, just separate the UI with other module. At least it can help you to emphasize SOC. Keep in mind that loading multiple assembly can be slower than a single assembly.
Is it the right approach of separating modules?
Module separation always has a drawback, that it is require mapping. It means slower performance in general (maybe negligible, but still there is), and slower development time. If your application will be large and complex enough, it is worth it, since you can create modular unit tests for each module.
How the real world modular applications are developed?
No exact practice though, every problem needs a solution. You won't need a heavy multi-threading or dependency injection architecture for a simple calculator application.
How should the different modules communicate with each other yet they stay independent of each other.
Using interface. You can make the implementation different later on. Example is, you currently use C# Winform for your application, communicate to the BLL using interface. Later on, you want to migrate to ASP.Net, then you just change the implementation, but keep the interface to communicate with the BLL the same.
I think there should be a core application which makes use of these modules, how should the core application communicate with these modules?
There is some data, entities , objects which are common to each module, should I put them in the core modules in order for other modules to use them (I think this will make the modules coupled to core) or should every modules maintain its own copy of data + define those object, (which I think voilates DRY)
I assume it is an enterprise level application which share the same modules / data such as employee. If it is really need to behave uniformly, then you should provide the very basic logic at the core Level. At the application / implementation level, you may has different implementation to fulfill each requirement.
Do not force to uniform all of the business logic to the core. If a specific application need a different implementation, it is hard to make the core configurable.
I am trying to think about a web application development framework for our product development. I want to build an ASP.NET application which has many sub-modules in it. My requirements are like:
The application will be a suite of different modules like CRM, Bugtracker, Inventory management, Finance management etc.
Each Module should have their own DLLs.
One project should be for the external container of the application (like the framework) and this project should bring all other modules (of type web application) in the solution to the external container. (Some thing like we have Frames in HTML). So we will publish the external container web application only at the end of the day and all other web application projects will be accessed via that.
I would like to have separate DLL for each module so I don't need to fear about the application breaking when I am deploying my single DLL which controls the entire suite.
I am not sure whether my thoughts are in the right direction. The end result I am looking for is a well-maintained, organized, and modular web application suite.
It is ASP.NET web forms, not MVC. I will use VS2010 for development.
What are the best approaches to do this?
Edit:
The term external container means it acts like a master page which has links to various modules and the various modules are not always in the same project. They can be separate project under the same solution. And I am under the impression that, by the end of the day, I will publish that project only and it will bring the various modules to it.
I actually think the best approach would be one that does not over-architect. I'm concerned that it seems you are producing an overall architecture without sufficient reason.
Are these all new modules? Then just start writing the first one. Use best practices that apply to single modules.
Then write the second one. You'll find you want to use things you already wrote in the first module. Great. That's what refactoring is for. Refactor these things out into one or more "library" projects, re-run all your unit tests, then proceed with the second module.
Repeat until all modules are done.
At the end of this process, if you needed the kind of architecture you've outlined, then you'll have it. If you needed less, then you'll have less, and you will not have spent time creating an architecture which is not tied to real-world requirements.
I'm not going to say this is a "best approach" but I would recommend looking over Dot Net Nuke (DNN) to get some ideas. This started as the old "I Buy Spy" starter web project that Microsoft distributed to show ASP.NET projects, and it took off from there.
edit:
1.The application will be a suite of different modules like CRM, Bugtracker, Inventory management, Finance management etc.
You can do this with DNN. They're also called "modules" in DNN and Drupal.
2.Each Module should have their own DLL's.
Yes, this is a good idea. And you'll see this sort of thing in several content management systems like DNN and Drupal. This way not all implementations of the same website need to have all modules installed.
We have a significant website that is used to host a "service as a solution" application that we charge for (if you aren't an actuary or accountant you won't have heard of it). The lead developer for the past couple years used an earlier version of DotNetNuke as a model for how to refactor the parts of the application that he was allowed to change.
Like others have suggested DNN would probably work for what you're trying to do. If you want to completely roll your own naturally I would turn to some sort of combination of a container "Framework" and a bunch of user controls (.ascx). The container could be as simple as a master page with a menu. Depending on how flexible you want your design you can prefabricate many different pages, each hosting a different control (separate dll as you wish). If you want it to be a little more dynamic you can have one content page that will dynamically load at runtime the desired user control into it. Again this is just a general approach, probably a 30000 feet view into how DNN is implemented anyway.
Name the main project after your company/product and keep it short and simple. You will probably need one or two library projects to support it - these will contain everyday, common logic for such things as error reporting, Web utility methods, etc.
Next, pick one of your intended sub-projects (I don't like the term module in this particular context) and add that to your solution. Whether you are reusing an existing project, or preferably starting from scratch, you will eventually have any common logic in this project moved out to your libraries.
Rinse and repeat. Perhaps take a look at something similar like the Sueetie project which includes several sub-projects like CMS, Blog, Calendar, Forum, etc.
The following article is marked as "outdated" on MSDN but I still think you should take a look at it:
Structuring Solutions and Projects
Also, something similar from the Patterns and Practices Group:
Structuring Projects and Solutions in Team Foundation Source Control
Let's say I have a Visual Studio solution with a Web project, a BLL project, and a DAL project. I'm trying to follow the repository pattern keeping my SQL code in the DAL with an interface that is referenced by the BLL.
I have a handful of common solutions for things such as error handling, usage logging, and other things that can be considered utility functions (i.e. not in the business spec). I'm keeping these in a Common project.
Here are a few ideas I've had with regards to structuring the Common project...
Bundle SQL with logic in a given class
Create a layered solution within the Common project
Discard the Common project and put utility functions in with BLL/DAL
Is one of these ideas better/worse than the other? Does anyone have a better solution?
It's worth noting that these utility functions will be reused in a variety of other applications.
Instead of creating a Utilities project which will be used have you thought about creating something that can provide a service? You might want to look at Aspect Oriented Programming. Red flags went up when I saw you listing off your examples error handling, logging, etc. Those scream AOP.
But if you want to stick with your layout.
I think I would go with 2, assuming that means restructuring the utilities project to be more Cohesive.
I don't understand (please clarify and I will edit my post)
Bundle SQL with logic in a given class
As for:
Discard the Common project and put utility functions in with BLL/DAL
I would be against doing so. If this logic is truly going to be repeated there is no need to push it back into your projects. This will lead to duplicate code and increased maintenance.
Side Note:
Just as a lessons learned, the only way Utilities projects work, are if you are the only developer or it is well documented and well designed. Sometimes utilities are too programmer specific, or are written in a way that only benefits a particular coders style.
I have seen countless times people rework their infrastructure pulling out all kinds of utilities, only to see their utilities project never get used. Make sure the "utilities" you are creating are truly useful to other people.
There is the requirement, to write a portal like ASP.NET based web application.
There should be a lightweigted central application, which implements the primary navigation and the authentication. The design is achieved by masterpages.
Then there are several more or less independent applications(old and new ones!!), which should easily and independent be integrated into this central application (which should be the entry point of these applications).
Which ways, architectures, patterns, techniques and possibilities can help and support to achieve these aims? For example makes it sense to run the (sub)applications in an iframe?
Are there (lightweighted and easy to learn) portal frameworks, which can be used (not big things like "DOTNETNUKE")?
Many thanks in advance for you hints, tips and help!
DON'T REINVENT THE WHEEL! The thing about DotNetNuke is that it can be as big or as small as you make it. If you use it properly, you will find that you can limit it to what you need. Don't put yourself through the same pain that others have already put themselves through. Unless of course you are only interested in learning from your pain.
I'm not saying that DNN is the right one for you. It may not be, but do spend the time to investigate a number of open source portals before you decide to write your own one. The features that you describe will take 1000s of hours to develop and test if you write them all from scratch.
#Michael Shimmins makes some good suggests about what to use to implement a portal app with some of the newer technology and best practice patterns. I would say, yes these are very good recommendations, but I would encourage you to either find someone who has already done it this way or start a new open source project on codeplex and get other to help you.
Daniel Dyson makes a fine point, but if you really want to implement it your self (there may be a reason), I would consider the following components:
MVC 2.0
Inversion of Control/Dependency Injection (StructureMap for instance)
Managed Extensibility Framework
NHibernate (either directly or through a library such as Sh#rp or Spring.NET
A service bus (NServiceBus for instance).
This combination gives you flexible user interface through MVC, which can be easily be added to via plugins (exposed and consumed via MEF), a standard data access library (NHibernate) which can be easily configured by the individual plugins to connect to specific databases, an ability to publish events and 'pick them up' by components composed at runtime (NServiceBus).
Using IoC and DI you can pass around interfaces which are resolved at runtime based on your required configuration. MEF gives you the flexibility of defining 'what' each plugin can do, and then leave it up to the plugins to do so, whilst your central application controls cross cutting concerns such as authentication, logging etc.
What are the benefits of Spring Actionscript considering Dynamic Proxies are not possible in the current version of Actionscript and Reflection is quite limited.
So for example I could specify my object creation in an XML application context, but why would I do that when I can simply specify that in code, and hence take advantage of static type checking etc.
It is by no means my intent to belittle the work done on Spring Actionscript but more to find an application for it in my projects.
Besides XML configuration, Spring ActionScript also supports MXML configuration. The type of config (XML, MXML) depends on the use cases your application needs to support. For the reasons you mention, it makes perfect sense to configure most of the context in MXML, but I would encourage you to externalize the config of service endpoints in every case.
In a past project we opted for XML config since the configuration was generated at runtime when a user logged on to the application. Depending on the user credentials, different endpoints and various different settings were used. We could not have done this elegantly with static MXML configs.
Both config types have their strengths and weaknesses, and it's up to you to decide what type you want to use. I think we could even support a mixture of MXML and XML quite easily actually if that would make sense. As soon as we have Dynamic Proxies and class loading, XML config will make a lot more sense.
I would agree with Sean in the general sense that trying to force Flex inside of the Java box is generally a bad idea. As many similarities as there are, Flex is not Java.
That being said, there are plenty of reasons why you might want to have some of your configuration in an external XML file, not the least of which is in the use case of configuring your service destinations and endpoints, where you may have a need to be able to change the endpoint URI without having to recompile your application.
There are several projects available that are simply misguided ports of philosophies from other platforms. Whenever starting in on a new platform, I think the best thing to do is figure out how people are effectively developing and go from there.
I say all of that because I think all of the java-esque frameworks for flex/flash leave you worse off than you started. You do need dependency injection, but there are good as3/mxml-friendly frameworks for that (Mate, Swiz). There is absolutely no point in using xml when you can use mxml, which is strongly typed.