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Development of a Web Application(CRM) in GWT

I am student. Currently, I am experienced with Core Java and very introductory Servlets and JSPs concepts.
For my summer internship, I have a task at hand where I am to develop a social CRM for a small startup.
I am very new to web development, I have no prior experience in this field, I am familiar with the technologies involved though, however I want to start off now and develop a good project in the summers.
I want to base my project on Java, I am considering using GWT for all client side AJAX work along with a J2EE server.
Would this be a right decision on my part? What is the learning curve involved with GWT? Can I really start off with something like a small CRM without doing nothing more than a HelloWorld previously?
Need some suggestions as to how should I kick start my work and progress quickly with concepts and my project as well.

If you want to develop a good project, like you say, then I believe this is a very fine choice. It's certainly not the easiest one (you could probably hack something quickly with PHP etc.), but I'd say that it really pays off.
I would suggest to follow the official tutorial and the remainder of the official documentation (stay away from the "Editors" framework for now though, it's madness at the moment.)
If you already have a solid background in Core Java, and if you get the right picture of how GWT works (eg which code is transformed to JavaScript / when HTTP requests will occur / ...) I think you can absolutely do it. Make sure to get some solid HTML/CSS and a little bit of JavaScript background first.
I must add, that I would personally not go the Roo route (sorry #jgrabowski) - especially not at first (probably not ever, even though Roo is probably a very good tool, if you like such tools.)
Understand the GWT technology,
create a few very simple prototype apps (just for fun),
then learn to apply best architecture practices, and improve your code.
And maybe you'll find, that a different architecture may even work better for your app (Just as an example: In the case of the largest application I'm currently working on, the generally-suggested MVP architecture would simply not work very well, at least not the way it's usually presented. So it's sometimes better to form a good solid understanding first, instead of blindly copying "best practices". Then you can make an informed decision, and develop a good project!)

You can start playing with Spring's Roo and generate GWT skeleton of your application. Then you can analyze it, try to understand it, improve it (and even remove Roo from it afterwards:-).
Roo is able to generate well architected GWT application that is inline with current best practices, so I believe it might be good start for you.

Found an excellent source for exploring GWT in depth.
I would stronly recommend the book "Google App Engine Java and GWT Application Development", as of now the book is quite updated on GWT, GAE and the APIs.
https://www.packtpub.com/google-app-engine-java-and-gwt-application-development/book

In recent months the GWT Activities and Places pattern has matured.
The example covered at http://code.google.com/webtoolkit/doc/trunk/DevGuideMvpActivitiesAndPlaces.html gives a broad introduction to the pattern. The downloadable sample will lead demonstrate how to 'slice' your application into Activities and Places. This pattern will take away some of your 'architecutre' concerns - you can just go with the flow and do it the A & P way.
Note, however the intro page and the demo code are very light on UI. Separate to your architecture planning you'll need to get up to speed on laying out a GWT app - but that's also covered well in the GWT articles. As #Chris-Lercher suggested, create a couple of UI prototypes that you're happy to throw away to get you started.

Java technologies for web-development

I'm PHP-programmer, but I'm extremely interested in learning Java. So I decided to change speciality from PHP to Java. At the moment I have an opportunity to try to make quite simple web-application (it should contain 2-3 forms, several pages with information from the database and authorization module) and also I have a chance to choose any technology I want. Besides I have about 3 months for this task. I've decided to develop site with Java technologies for the purpose of studying. I've already read a book about Java ("Java2 Complete Reference" by P.Naughton) and currently I'm reading "Thinking in Java" by B.Eckel. I clearly understand it's not enough for efficient development, but I want, at least, to try.
I would be very appreciated for the advises, which framework (for example) or technology to choose (Spring, Grails etc.) and what primary aspects and technologies of Java should I pay attention to?
Thank you in advance.

Get yourself a copy of Head First Servlets and JSP. It will walk you through web application development, I would not jump into using spring straight away after you have mastered traditional Servlets you will feel more comfortable looking at Spring Roo or Spring MVC.

I have written about this some time back, which you might find useful.
http://veerasundar.com/blog/2009/04/what-advice-will-you-give-for-a-j2ee-fresher/
Note: Even though it's my blog, I'm linking it here because it has some relevant content. This is not for any link-building and traffic-getting tricks. :)

If you have such simple requirements just use Spring Roo. It might be also an alternativ to take a look at Ruby on Rails.

One framework that might want to look at is Trindad/ADF.
Apache Trinidad is an open-source framework that runs on top of JSF. It's a pure Java environment that let's you define a web-page via declarative XML. It works very well since you spend much less time fiddling with the general page layout and simply declare what sort of functionality you want.
For example:
<tr:commandButton text="Click me" actionListener="#{BackingBean.fireEvent}" />
Will create a button with the text "click me" and will fire the fireEvent(ActionEvent ae) function on BackingBean.
ADF is a similar framework, it features many more bells and whistles and much better JS API but it's also non-cheap.

Grails or Play! for an ex-RoR developer?

I plan to start learning a Java web framework (I love the Java API) I have already used Rails and Django.
I want something close to Java but without all the complexity of J2EE.
I've found 2 frameworks that could be good for me:
Grails
Grails looks great, it uses Groovy which is better than Java for web application (I think..) but it's slower than pure-java based frameworks (Hibernate, Strut, Spring) It looks pretty simple to deploy (send .war and it's ok!), the GSP is great! It's a bit harder to debug (need to restart the server at each modification and stacktraces contain a mix of Java and Groovy traces which is not always the easiest to understand)
Play!
This framework also looks great; it's faster than Grails (It uses Java) but I don't really like how it uses Java, it modifies the source code to transform the property calls as setXXX/getXXX, I do not like that... The framework also has a caching function that Grails does not have. I don't really like the Template Engine.
It's also easer to debug (no need to restart the server, stacktraces are clearer)
What do you recommend?
I am looking for something easy to learn (I have a lot of Ruby experience, not so much Java experience but I love the Java API), fully featured (That's no a problem with all the Java Library available, but if it's bundle and integrated I prefer), has good scalability and is not too slow (faster than Ruby) Ideally I would like to use a framework with a decent community to easily find support.
PS: I am not interested in JRuby on Rails

I switched from Grails to Play and I never looked back. My biggest problem with Grails was overall robustness and developer usability. Most of the time I got bitten by the fact that Grails glues together the usual stack of Spring MVC and Hibernate while trying to hide this fact and giving you a Rails-like API (personal opinion of mine). The problem with this is, once something goes beyond the trivial samples, it easily broke and didnt work for me. Developing with it was like walking on eggs (for me). Whenever I googled for documentation of a feature I needed, I was not redirected to samples, tutorials, blogs, but to the Grails JIRA explaining me why the feature wouldnt work for my use case and that the bug was unresolved since two versions before the one I was using.
While that may not be the overall experience for every developer (I am not writing this to bash Grails, but to give my experiences with it here), I needed something that helped me and would not stand in my way or break down on me when I needed it the most. Thats when I found Play and I have quickly migrated my app to it after I found out about it (around the ~1.0 release).
So far it has been a great ride and for the first time in my web development career, I have stopped looking at other frameworks trying to find something that I would like better.
If I had to close with one thing that Play did better than Grails - at least for me - it would be the fact the Play is built from the ground up with developer usability in mind. It does not sacrifice ease of use for enterprise buzzwords. It has the guts to throw away what does not fit into this paradigm (e.g. ditchting Servlet-based runtimes during development for faster turnaround). It is willing to make compromises in order to guarantee awesomeness. And that is something I have only seen in communities like Rails or Django before I found Play.

I'd suggest Grails. It has a bigger community than the play framework does (~350 plugins covering pretty much every basic need). Also, grails is written almost completely in Java, it just lets you use Groovy for your domain specific implementation.
If you do run into a performance issue where the groovy pages that you've created are the bottleneck, you can always just switch to a Java implementation. Then you're in the same boat that you would have been with the Play framework all the time. You've optimized your development time by putting off the coding of things in Java till you know that you actually need to do it (which, in my experience is very rare).
I'm also not sure where you heard that you need to restart your server for each modification, but that's actually not true. Grails supports reloading of controllers/gsps/services/domain objects, etc without restarting your server.
The mixed stacktraces can get a little long, but tool vendors (like Intellij) have made some recent improvements that strip out all the stacktrace portions that you don't care about.
I've been using grails since the .5 days and have been very happy with the platform.

Take note that the Play! framework now supports using Scala as of 1.1

From my experience with Play it's a great framework. My favorite features are the cool controller system and the template system - both are simple but feature-rich and powerful.
However the most important benefit of Play is definitely the rapid development cycle, where virtually no reloading is needed on code changes. But if you're not careful, this greatness won't last much, and slowness will eventually creep into your code.
Why is that?
With Play there is common use of some plugins with pretty heavy initialization, notably EJB (Hibernate) and Spring. The initialization of these plugins is re-run on every code change before the new code is loaded. As a result of this, as your model and your system configuration grow, this heavy initialization starts to seriously slow down your development. In the system I used 20 seconds were a typical startup time on a virtual machine running on a kickass laptop.
What you can do to avoid this depends on your application, e.g. if you're building a NoSQL application then then EJB plugin should not give you trouble. Spring can be replaced with a custom hard-coded Java plugin, which IMHO is also easier to maintain, or run a Groovy script if scriptability is that important. In any case, watch out for these problems and kill them while the're young - and be sure not to be running your own bulky initializations on every refresh.

If you have used Ruby and Python before, you will probably enjoy Grails better than Play. It very hard to get back to Java once you are used to these dynamic languages.

There is also Lift on Scala.
Imho scala is the best static typed language and lift is a pretty nice framework (for a static typed language).

Does it make sense to use a framework for a simple java web app?

I've done lots of java web development using jsps and servlets, and I have found this approach to be straightforward and flexible. Some of the groundwork involved though - such as managing database connections - is rather tedious, and it takes a fair amount of work just to get a new web app off the ground.
I'm therefore considering using a framework for the first time, but my impression of frameworks is that they're mostly used for large J2EE applications and involve a lot of complex configuration. What I'm looking for is something simple that (after the initial learning curve) will enable me to get up and running with a new web app as quickly as possible.
So my question is - does it make sense to use a framework for a simple java web app?
Note that I'm not asking which framework to use (if indeed a framework is recommended), as it has already been asked here.

If you don't use a web framework you'll usually end up writing one - poorly.

It makes a lot of sense. My team has spent the better part of five years with our open source stack and no matter and we have a "seed" project (works like appfuse) that we use to create all new web apps. Even the simple two pagers from the pov of maintaining the app, it looks like every other app, just smaller.
The short is you won't get any return on the investment right now, but you will as the project evolves and you maintain it.

Yes, I would use a web framework for the following reasons:
Increased navigation capabilities and controls. Even though you may not need them, they are there for you to use should you require them at any time
As others have indicated, apps grow over time and you will feel the need for the framework at some point in time in the future. When you need to add additional pages and navigation
Features that allow you to plug into other frameworks such as security and DB access frameworks. Spring is a prime example in the Java world. You never have to use Spring but it plugs in so well with Struts, Spring MVC, Hibernate, Acegi etc. It ends up saving you the hassle of doing all of the plumbing on your own.
Support!!! Good frameworks almost always have a vibrant community to support them and ask and answer questions.
It may seem like too much hassle initially but definitely saves you much time in the future

I'd say it actually matters quite a lot which framework you go for. Something like Spring MVC is fairly unobtrusive in your code and allows you existing stuff to run quite a lot as-is. Other frameworks have much more specific ideas about how you should do things.

Yes it does make sense. Apps can grow and change and might require something a framework can provide easily in the future.
For example at my workplace we have simple jsp / servlet app. It needs to be rewritten just because of what I explained above. If someone would have taken the time to just get the framework setup we would be in better shape today.

Yes it makes sense. However implicit in your question is that the wrong (for you) framework can be more pain than it's worth - and that's true. There is a world of difference between some heavy J2EE framework and something light and cheerful like grails.

What's the alternative? Rolling your own? Embedding all the navigation and logic in the JSPs?
I agree with those who say that a web framework is worth it. There are literally hundreds now (e.g., Struts, JSF, Spring, Wicket, etc.). Pick one that suits you.

There are two kinds of applications:
1) the kind that you throw away and never use again, and therefore should not worry about modularity, maintainability and clarity.
2) the real kind.
It may sometimes seem that your app may never have to grow, scale, or service a larger feature set / user base than you currently are planning for....I assure you, that perception is always wrong.
Frameworks, specifically things like Struts for MVC in Java, Spring for MVC and Dependency Injection, Hibernate for Object-Relational Modeling are all extremely valuable tools that lead to modularity, maintainability and clarity in your code. So, to answer your original question.... Yes, emphatically.

No it doesn't unless:
you don't have any java experience
in your team
you are doing just a prototype that
must be ready in hours
you don't trust your developers
enough to let them write your
application
you don't plan to let your
developers learn and improve
Danger in using frameworks include but not limited to:
you'll get all framework defects on
top on your own
you'll be unable to do realistic estimates until you
know perfectly the framework
your team won't learn how to program a
web server
you'll find your team passing more
and more time on google instead that
solving problems by writing code.
The only thing that is worst that choosing a open source framework is having a separate R&D team in the company who should create the "big complete ultimate company framework".

but my impression of frameworks is that they're mostly used for large J2EE applications and involve a lot of complex configuration
Not necessarily true. The good frameworks are built to scale well so that they will take you from small apps to very large apps. Many of the frameworks today are moving towards zero configuration so you will find them easier and easier to use.
You are right that it does take an initial effort to learn the framework itself but that investment pays for itself in the very first application you build. And meta frameworks like AppFuse makes it even easier to get started since it pre-configures the frameworks for you.

Frameworks make sense for most applications. It may be necessary for you to build your own or adopt some other framework. The most important questions is the granularity of your data structures. What I mean by this is do you need to just enter data or do you need to parse, compile and execute dynamic code?
If you think of a frame works as a gauge and to the left is an all ready existing frame work open source or closed and to the right is all custom framework then super impose your code on top of that frame work where the level of complexity increases to the right. The farther right you go the more of a stuggle you will have with the frame work (IMO).
However, you can also slowly migrate from existing to custom framework.
There is also the question about your business. If you work for a business that does not look at software as it's core compentency such as a bank or hospital then you need to way that into how much of a frame work you want to build.
Bottom line a framework of some type will always be useful.

Using a framework may add some overhead to your web-app development due to the learning curve. However, depending on the framework you choose, you may be able to realize the following benefits:
Scalability
Maintainability
Clear Division of your model (e.g. MVC)
Out-of-the-box components(SessionManagement,authentication,etc )
Third party plugins
Modularity inherited from the framework
Many others.
Besides, the learning curve is a variable factor. Some frameworks may be easier to learn than others depending on your skills.

It definitely makes sense to look into using a framework even if for no other reason than it'll give you a new area of knowledge. If you've got the time to invest in learning a framework then you may well find in time that it's easier and faster to use that for new projects no matter how simple they are.
Also, if I could vote for SamBeran's post then I would. Getting started with a framework will involve several moments of "oh great! I don't need to write all that boilerplate again!".

I'd say use one - like you said, it's rather tedious to get stuff up and running for even a simple java web app. If the framework helps you get the job done faster and provides the services you need, I'd say it makes sense.

Using java (desktop) codebase in a webapp

I have a rather large (80k loc) java desktop app that talks to a database. We're now looking at exposing some parts of the database via a web application, using the existing codebase and preferably not having to modify it.
I have good separation between the data access, business logic and presentation layers, but we haven't used enterprise java beans or anything like that (if that's important).
What's the best way forward? Which of the java web frameworks will be best suited to the problem? Learning curve isn't terribly important, since I haven't done any java development on the web...

To be true, it depends what you already have, and how well is the design of your current desktop application. You might not be able to use any or may be minimal of your existing code without modifying it, if its designed badly, and everything is tightly coupled.
Assuming that you are having a system with a good design, everything is de-coupled well enough. You can look into Stripes to make your presentation for the web, and use your existing data access and business code. I wish you all the luck.
Few other goodies to look into are, Groovy on Grail, Wicket.
I don't recommend anything like Seam and Spring they are more of a container and sophisticated large frameworks, which give you almost everything, solution for almost all of your problems. As you mentioned that you already have a complete system, and you just need to make a web interface to publish it for the web, these are not recommended, IMO.
JSF, is a good framework, but it might drive you nuts and has a big learning curve, according to few folks.

The two frameworks I would recommend would be Grails and Struts 2.
Grails comes with a whole bunch of stuff that it configures under the covers including Hibernate and Spring. It makes generating dynamic pages to send to the browser ridiculously easy. What you are probably going to need to do is set up controllers that call Grails services which reference your existing code as you probably don't want Grails managing your database interactions. The disadvantage with Grails is not so much that it is written in Groovy, which is easy to learn for Java programmers, but that the IDE support for Groovy is still maturing. Still if you want quick productivity this is the route to go down.
Struts 2 offers a clean command pattern framework implementation that talks to JSPs (or velocity or FreeMarker templates) on the front end. To use this you would configure actions to call your existing code. You may want to investigate adding Spring to the mix depending on what you need to do.
There are other choices but these are two that I have had some success with.