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I'm starting to study Dart. It seems a nice language and in some aspects a real improvement over JavaScript. Since it claims to come with "batteries included" and to be meant for "structured web apps", though, I fail to understand how to actually structure a web app with it. Almost all the tutorials concentrate on language features, but Dart is quite simple and with many familiar bits, so that's the easy part.
Recently I fell in love with AngularJs. Now routing, two way binding, nested scope, clean separation of concerns... This actually means "structured" to me. But all the Dart examples I find are about selecting HTML elements and attaching listeners to them. This is old-style jQuery-like web programming and quite frankly the opposite of what I think of when I read "structured".
I don't want to compare a language and a framework and I know that Angular Dart is out, but I fear I'm missing something of vanilla Dart, because if it's all about a shorter syntax for lambdas, class based OOP vs prototypical OOP and the like, I don't see how it's supposed to be a game changer: there are many other languages that provide an alternative JS syntax (à la CoffeeScript) and compile to it, and they don't come at the price of losing a perfect integration with existing JavaScript libraries and tools.
Sure, it has optional static typing, which may be great, but this comes more to a matter of preferences. I'm a full time Python and Ruby developer and I'm perfectly fine with dynamic languages. Is this what they mean by "structured"?
Thanks for any clarification that will eventually come.
I work on AngularDart and have some experience structuring web apps.
When building a web app in Dart you would pick a web app framework, for example AngularDart or polymer.dart. Web app frameworks have a lot of opinion which is something that doesn't fit in the core libraries. In that respect, "vanilla Dart" is fairly vanilla.
Since I'm most familiar with Angular, I'll discuss the Angular + Dart combination. However, the rest of this post is also true for polymer.dart.
Angular provides a lot of structure to your app. We've been able to provide a similar structure for both Dart and Javascript. The concept of directives, data binding and dependency injection exist in both.
Dart provides more structure and we've been able to use that structure while building AngularDart. e.g. the directive API is defined in terms of annotations which means that IDEs understand them and can help you code.
There are a number of "structure" features in Dart. One of my favourites is tooling. With types and annotations comes better tooling support.
Types in Dart are most useful when combined with tools. Auto-complete is great but for large web projects, static analyze is even better. For example, in AngularDart, since directives are annotated classes, we can assert that the annotation is correct. Even more interesting is the potential to build tools. In AngularDart, we have a tool that extracts and analyzes all directives. This type of tooling is possible in Javascript but easy and supported by the language in Dart.
libraries, packages
integrated dependency management with pub package manager
class based instead of prototype based
scopes of variables as one would expect in a modern language
static syntax check
better tooling support like code completion
Besides the obvious differences between JavaScript and Java, what are the relevant differences in using either SmartClient or SmartGWT?
SmartGWT is the GWT wrapper for SmartClient, which, as you say, means that you're able to write your SmartGWT app using java.
From my experience the only difference that matters when you're programming is that the GWT wrapper is a bit more restrictive than using the js components directly. For example, programmatically scrolling a TreeGrid from java is hell, since the body of the underlying table (that you need to get at in order to scroll the blasted thing) is not exposed through SmartGWT, while it of course is easily reachable from js.
Overall I wouldn't base the choice between the js components and the gwt wrapper soley on these differences, but I would look at other factors in your project. Which techniques are you most comfortable with? How much custimization are you planning on doing?
In my case, code maintainability.
We are a Python house. But for client-side code we opt for GWT, initially with GXT, but now with SmartGWT.
We don't like Java, but we don't like JS much more, Order, maintain libraries for several widgets, extends objects to give custom functionality, etc. between doing this in JS or Java, the option was obvious, Java side. We write reusable components here, and now we write very minimal code for client side, only reuse components and use REST to comunicate with ours Python backends.
We know that SmartGWT is more verbose than SmartClient, but, with Netbeans autocompletion (some coleagues here use Eclipse) we have direct access to every method, documented, instead to go to the showcase or google every time that we need to test and try new functionality.
SmartGWT provides you the advantage that you may use powerful editors.
You can debug your own code easily (however it's not very helpful for diving into the smartclient code itself).
You have all the auto completion stuff of eclipse/netbeans at hand. When starting to work with SmartClient/Gwt it helps you find the things you are looking for because the editor can list you classes or the available methods and some basic documentation what the class/method actually does. Saves you a lot of time crawling through the docs
Banang : API's to access ListGrid / TreeGrid body are now exposed in Smart GWT.
We chose to use Javascript (no SmartGWT) ... I prefer it that way, although some of our team members (newer to Javascript) would have preferred the SmartGWT way. Both have their pros and cons :
One of the advantages of using SmartGWT, is that you get to have compile time errors since everything gets compiled first by the Java compiler, before it gets rendered to Javascript.
One of the drawbacks of SmartGWT, is that it doesn't expose the full underlying Javascript Smartclient API. This means, if you want to do more advanced stuff, you might end up needing to do it in Javascript anyways.
Another drawback of SmartGWT, productivity wise, is that every single change you do and want to test, needs to go thru the painful Java EE compile/deploy process, whereas if you do it in Javascript, you can alter client side code faster by changing .js files directly without the need for the whole compile/deploy process.
SmartGWT is based on java code and when compiled it transforms it into java script, is a
heavy since it transforms java code into js
SmartClient is a framework based on js, you can use its components in an xml page and you manipulate them in Js, and it’s light
le showcase de smartclient
I recommend smartClient
XML seems to be the language of the day, but it's not type safe (without an external tool to detect problems) and you end up doing logic in XML. Why not just do it in the same language as the rest of the project. If it's java you could just build a config jar and put it on the classpath.
I must be missing something deep.
The main downside to configuration DI in code is that you force a recompilation in order to change your configuration. By using external files, reconfiguring becomes a runtime change. XML files also provide extra separation between your code and configuration, which many people value highly.
This can make it easier for testing, maintainability, updating on remote systems, etc. However, with many languages, you can use dynamic loading of the code in question and avoid some of the downsides, in which case the advantages diminish.
Martin Fowler covered this decision pretty well here:
http://martinfowler.com/articles/injection.html
Avoiding the urge to plagiarize... just go read the section "Code or configuration files".
There's nothing intrinsically wrong with doing the configuration in code, it's just that the tendency is to use XML to provide some separation.
There's a widespread belief that somehow having your configuration in XML protects you from having to rebuild after a change. The reality in my experience is that you need to repackage and redeploy the application to deliver the changed XML files (in the case of web development anyway), so you could just as easily change some Java "configuration" files instead. Yo could just drop the XML files onto the web server and refresh, but in the environment I work, audit would have a fit if we did.
The main thing that using XML configuration achieves in my opinion is forcing developers to think about dependency injection and separation of concerns. in Spring (amongst others), it also provides a convenient hook to hang your AOP proxies and suchlike. Both of these can be achieved in Java configuration, it is just less obvious where the lines are drawn and the tendency may be to reintroduce direct dependencies and spaghetti code.
For information, there is a Spring project to allow you to do the configuration in code.
The Spring Java Configuration project (JavaConfig for short) provides a type-safe, pure-Java option for configuring the Spring IoC container. While XML is a widely-used configuration approach, Spring's versatility and metadata-based internal handling of bean definitions means alternatives to XML config are easy to implement.
In my experience, close communication between the development team and the infrastructure team can be fostered by releasing frequently. The more you release, the more you actually know what the variability between your environments are. This also allows you to remove unnecessary configurability.
A corollary to conway's law applies here - your config files will resemble the variety of environments your app is deployed to (planned or actual).
When I have a team deploying internal applications, I tend to drive towards config in code for all architectural concerns (connection pools, etc), and config in files for all environmental config (usernames, connection strings, ip addresses). If there different architectural concerns across different environments, then I'll encapsulate those into one class, and make that classname part of the config files - e.g.
container.config=FastInMemoryConfigurationForTesting
container.config=ProductionSizedConfiguration
Each one of these will use some common configuration, but will override/replace those parts of the architecture that need replacing.
This is not always appropriate however. There are several things that will affect your choice:
1) how long it takes after releasing a new drop before it is deployed successfully in each production environment and you receive feedback on that environment (cycle time)
2) The variability in deployed environments
3) The accuracy of feedback garnered from the production environments.
So, when you have a customer who distributes your app to their dev teams for deployment, you are going to have to make your app much more configurable than if you push it live yourself. You could still rely on config in code, but that requires the target audience to understand your code. If you use a common configuration approach (e.g. Spring), you make it easier for the end users to adapt and workaround issues in their production.
But a rubric is: configurability is a substitute for communication.
XML is not meant to have logic, and it's far from being a programming language.
XML is used to store DATA in a way easy to understand and modify.
Has you say, it's often used to store definitions, not business logic.
You mentioned Spring in a comment to your question, so that suggests you may be interested in the fact that Spring 3 lets you express your application contexts in Java rather XML.
It's a bit of a brain-bender, but the definition of your beans, and their inter-dependencies, can be done in Java. It still keeps a clean separation between configuration and logic, but the line becomes that bit more blurred.
XML is mostly a data (noun) format. Code is mostly a processing (verb) format. From the design perspective, it makes sense to have your configuration in XML if it's mostly nouns (addresses, value settings, etc) and code if it's mostly verbs (processing flags, handler configurations, etc).
Its bad because it makes testing harder.
If you're writing code and using methods like getApplicationContext() to obtain the dependencies, you're throwing away some of the benefits of dependency injection.
When your objects and services don't need to know how to create or acquire the resources on which they depend, they're more loosely coupled to those dependencies.
Loose coupling means easier unit testing. Its hard to get something into a junit if you need to instantiate all its dependencies. When a class omits assumptions about its dependencies, its easy to use mock objects in place of real ones for the purpose of testing.
Also, if you can resist the urge to use getApplicationContext() and other code based DI techniques, then you can (sometimes) rely on spring autowiring which means means even less configuration work. Configuration work whether in code or in XML is tedious, right?
I believe that most IoC containers allow you to wire dependencies with XML configuration file. What are cons and pros for using configuration file vs. registering dependencies in code?
These pros and cons are based on my work with spring. It may be slightly different for other containers.
XML
pro
flexible
more powerful than annotations in some areas
very explicit modelling of the dependencies of your classes
con
verbose
difficulties with refactoring
switching between several files
Annotations
pro
less file switching
auto configuration for simple wirings
less verbose than xml
con
more deployment specific data in your code (usually you can override this with xml configs)
xml is almopst(?) always needed, at least to set up the annonation based config
annotation magic may lead to confusion when searching for the class that is used as dependency
Code
pro
Can take advantage of strongly-typed languages (e.g. C#, Java)
Some compile-time checking (can't statically check dependencies, though)
Can take advantage of DSLs (e.g. Binsor, Fluent interfaces)
Less verbose than XML (e.g. you don't need to always specify the whole assembly qualified name (when talking .net))
con
wiring via code may lead to complex wirings
hard dependencies to IOC container in the codebase
I am using a mix of XML+Annotation. Some things especially regarding database access are always configured via xml, while things like the controllers or services are mostly configured via annotations in the code.
[EDIT: I have borrowed Mauschs code PROs]
XML pros:
Can change wiring and parameters without recompiling. Sometimes this is nice to have when switching environments (e.g. you can switch a fake email sender used in dev to the real email sender in production)
Code pros:
Can take advantage of strongly-typed languages (e.g. C#, Java)
Some compile-time checking (can't statically check dependencies, though)
Refactorable using regular refactoring tools.
Can take advantage of DSLs (e.g. Binsor, Fluent interfaces)
Less verbose than XML (e.g. you don't need to always specify the whole assembly qualified name (when talking .net))
I concur. I have found ioc containers to give me very little, however they can very easily make it harder to do something. I can solve most of the problems I face just by using my programming language of choice, which have allways turned out to be simpler easier to maintain and easier to navigate.
I'm assuming that by "registering dependencies in code" you mean "use new".
'new' is an extraordinarily powerful dependency injection framework. It allows you to "inject" your "dependencies" at the time of object creation - meaning no forgotten parameters, or half-constructed objects.
The other major potential benefit is that when you use refactoring tools (say in Resharper, or IntelliJ), the calls to new change too
Otherwise you can use some XML nonsense and refactor with XSL.
I've got to do some significant development in a large, old, spaghetti-ridden ASP system. I've been away from ASP for a long time, focusing my energies on Rails development.
One basic step I've taken is to refactor pages into subs and functions with meaningful names, so that at least it's easy to understand # the top of the file what's generally going on.
Is there a worthwhile MVC framework for ASP? Or a best practice at how to at least get business logic out of the views? (I remember doing a lot of includes back in the day -- is that still the way to do it?)
I'd love to get some unit testing going for business logic too, but maybe I'm asking too much?
Update:
There are over 200 ASP scripts in the project, some thousands of lines long ;) UGH!
We may opt for the "big rewrite" but until then, when I'm in changing a page, I want to spend a little extra time cleaning up the spaghetti.
Assumptions
The documentation for the Classic ASP system is rather light.
Management is not looking for a rewrite.
Since you have been doing ruby on rails, your (VB/C#) ASP.NET is passable at best.
My experience
I too inherited a classic ASP system that was slapped together willy-nilly by ex excel-vba types. There was a lot of this stuff <font size=3>crap</font> (and sometimes missing closing tags; Argggh!). Over the course of 2.5 years I added a security system, a common library, CSS+XHTML and was able to coerce the thing to validate xhtml1.1 (sans proper mime type, unfortunately) and built a fairly robust and ajaxy reporting system that's being used daily by 80 users.
I used jEdit, with cTags (as mentioned by jamting above), and a bunch of other plugins.
My Advice
Try to create a master include file from which to import all the stuff that's commonly used. Stuff like login/logout, database access, web services, javascript libs, etc.
Do use classes. They are ultra-primitive (no inheritance) but as jamting said, they can be convenient.
Indent the scripts properly.
Comment
Write an external architecture document. I personally use LyX, because it's brain-dead to produce a nicely formatted pdf, but you can use whatever you like. If you use a wiki, get the graphviz add-in installed and use it. It's super easy to make quick diagrams that can be easily modified.
Since I have no idea how substantial the enhancements need to be, I suggest having a good high-level to mid-level architecture document will be quite useful in planning the enhancements.
On the business logic unit tests, the only thing I found that works is setting up an xml-rpc listener in asp that imports the main library and exposes the functions (not subroutines though) in any of the main library's sub-includes, and then build, separately, a unit test system in a language with better support for the stuff that calls the ASP functions through xml-rpc. I use python, but I think Ruby should do the trick. (Does that make sense?). The cool thing is that the person writing the unit-test part of the software does not need to even look at the ASP code, as long as they have decent descriptions of the functions to call, so they can be someone beside you.
There is a project called aspunit at sourceforge but the last release was in 2004 and it's marked as inactive. Never used it but it's pure vbscript. A cursory look at the code tells me it looks like the authors knew what they were doing.
Finally, if you need help, I have some availability to do contract telecommuting work (maybe 8 hours/week max). Follow the link trail for contact info.
Good luck! HTH.
Since a complete rewrite of a working system can be very dangerous i can only give you a small tip: Set up exuberant tags, ctags, on your project. This way you can jump to the definition of a function and sub easy, which i think helps a lot.
On separating logic from "views". VBScript supports som kind of OO with classes. I tend to write classes which do the logic which I include on the asp-page which acts as a "view". Then i hook together the view with the class like Username: <%= MyAccount.UserName %>. The MyAccount class can also have methods like: MyAccount.Login() and so on.
Kind of primitive, but at least you can capsulate some code and hide it from the HTML.
My advice would be to carry on refactoring, classic ASP supports classes, so you should be able to move all everything but the display code into included ASP files which just contain classes.
See this article of details of moving from old fashioned asp towards ASP.NET
Refactoring ASP
Regarding a future direction, I wouldn't aim for ASP.NET web forms, instead I'd go for Microsoft's new MVC framework an add-on to of ASP.NET) It will be much simpler migrating to this from classic ASP.
I use ASPUnit for unit testing some of our classic ASP and find it to be helpful. It may be old, but so is ASP. It's simple, but it does work and you can customize or extend it if necessary.
I've also found Working Effectively with Legacy Code by Michael Feathers to be a helpful guide for finding ways to get some of that old code under test.
Include files can help as long as you keep it simple. At one point I tried creating an include for each class and that didn't work out too well. I like having a couple main includes with common business logic, and for complicated pages sometimes an include with logic for each of those pages. I suppose you could do MVC with a similar setup.
Is there any chance you could move from ASP to ASP.Net? Or are you looking at keeping it in classic ASP, but just cleaning it up. If at all possible, I would recommend moving as much as possible moving to .Net. It looks like you may be rewriting/reorganizing a lot of code anyway, so moving to .Net may not be a lot of extra effort.
Presumably someone else wrote most or all of the system that you're now maintaining. Look for the usual bad habits (repeated code, variables that are too widely scoped, nested if statements, etc.), and refactor as you would any other language. Keep an eye out for recurring things in the same file or different files and abstract them into functions.
If the code was written/maintained by various people, there might be some issues with inconsistent coding style. I find that bringing the code back into line makes it easier to see things that can be refactored.
"Thousands of lines long" makes me suspicious that there may also be situations where loosely-related things are being displayed on the same page. There again, you want to abstract them into separate subroutines.
Eventually you want to be writing objects to help encapsulate stuff like database connectivity, but it will be a while before you get there.
This is very old, but couldn't resist adding my two cents. If you must rewrite, and must continue to use classic ASP:
use JScript! much more powerful, you get inheritance, and there some good side benefits like using the same methods for server-side validation as you use for client-side
you can absolutely do MVC - I wrote an MVC framework, and it was not that many lines of code
you can also generate your model classes automatically with a bit of work. I have some code for this that worked quite well
make sure you are doing parameterized queries, and always returning disconnected recordsets
Software Development Project Management practices indicates that softwares like this are requiring to retire.
I know how hard it is to do the right thing, even more when the responsible manager knows sht and is scared of everything other than the wost way possible.
But still. It's necessary to start working on the development of a new software. It's simply impossible to maintain this one forever, and the loger they wait for retiring it the worse.
If you don't have proper specification/requirements documentation (I think no asp software in the world does, given the noobatry hability of those coders), you'll need both a group of users that know the software features and a manager to be responsible for validating the requirements. You'll need to review every feature and document its requirements.
During that process you'll go learning more about the software and its business. Once you have enough info, you can start developing a new one.