This question contains a lot of background information, to make sure you fully understand why we are looking at these technologies.
The question is basically this:
For a large, spreadsheet-type, module that we need to develop for our webmodule for our application, are there any pitfalls we should know about if we decide to use Silverlight for it?
Issues we already know, and don't need any discussion/reminders about:
We're aware of the problems around using a plugin-type solution, which may or may not be installed on the users machine (and in some cases, probably can't be installed). These risks needs to be mitigated, but we're aware of them. Please don't get hung up on this.
We're a .NET company, so while ruby on rails and lots of other different platforms and architectures are good for this solution, they are not in the scope of the decision here. We have lots of code already written in .NET that we need to take advantage of, otherwise the project will never be finished regardless of platform.
Background
We have a web module for our application with employee-related information and some input forms. Our Windows desktop application is mostly a department leader type of application, to manage employees, but the web module contains mostly employee-centric functions. The web module contains mostly report-type webpages, to list information from the system, or input-forms.
The module we need to add now is more of a heavy spreadsheet type application. You change something one place, and something changes somewhere else, like sums, what is enabled/disabled, etc.
We know we can manage all of that with AJAX, but another issue here is that the application will potentially load a lot of database data in order to put the data in front of the user, and with a AJAXy solution, we're afraid that the request/response method here will have to reload quite a lot of information on every request, even to respond to seemingly easy questions.
A way to mitigate that would basically be to load information into a Session-object or similar, but that's a big no-no, so we'd rather not do that. This is a multi-user module, and some of the data is rather static, but some of the data is also going to have to be refreshed from time to time, so if 10 users loads a lot of data into the session, that's going to be a pretty big memory-hit.
We will be using ASP.NET (MVC) for this if we choose to go this route, that is, developing the module in pure HTML and similar technologies.
Then we looked at Silverlight, and would then load all the information down into the Silverlight application on the client. It would hold the current state, and would only need to touch the database to refresh some of the information, some of the time, instead, as we think the request/response model with ASP.NET (MVC) would work, on every little request.
But, since we have only done minor things with Silverlight, we're not that experienced with it, and we're afraid that some assumptions we might have, stated or unconcious, turns out to be wrong or flawed, which will make this project impossible or very hard to manage at some point.
For instance, just to take an example, is there a limit to how much memory the Silverlight application is allowed to load (I know, if I have to ask I can probably not afford it), for instance if there is a limit on 10MB, then that would be nice to know about before we're midway and start to load the really heavy data.
To make it simpler to give examples, let's just assume we're building a spreadsheet, that has so much data, that for the simple "changed a number here, what else changed", too much data from the database has to be loaded for a proper request/response model to be used, and if we move the entire thing to Silverlight, what will make that project hard or impossible?
Knowing about such things would at least give us the ability to consider if the price is acceptable.
In short, why should we not use Silverlight for this and instead go for ASP.NET (MVC)?
And again, "use Ruby on Rails instead", is not really an answer here. The options are ASP.NET (MVC) which we have experience with, or Silverlight which we don't but can gain.
Of course, if Ruby on rails, given that we'd have to start pretty much from scratch infrastructure-wise, and have to learn a new programming language, and framework, and download and learn a new IDE/tool, if it would still allow us to cut the development time in half, then please give us some information about how that might work, but I daresay that won't really happen here.
You should know that Silverlight (version 3.0) does not support any printing whatsoever, which to me sounds like a whopper of a showstopper for you (sorry, I couldn't resist). The good news is that full printing support has been added in version 4, but that is still in beta. Rumours say it should be out before the summer if everything works out according to plan, so if that fits with your roadmap I would use SL4 right from the start.
There are no memory limitations in Silverlight, but for the local storage (IsolatedStorage) mechanism there is a default limit of 1MB. But you can easily get around that by asking the users permission to increase the local storage space when he/she starts up the application. More on that here: Silverlight Tip of the Day #20 – How to Increase your Isolated Storage Quota.
(Edit)
Aside from the missing printing functionality that will be fixed in SL4 I cannot see any problems with your scenario. I would easily take the Silverlight route if I were you, especially since you already have extensive knowledge of .NET/C#.
For a rich interface as you've described, I would definately go with Silverlight or Flash rather than a html/javascript/ajax solution.
These technologies make for much better and consistent interfaces across platforms, you can buy in various components to speed things up and support things like copy-n-paste and code in a more structured way.
Another element is skills, if you have the skills to achieve it in a particular technology, then go with that.
To the answer you question the best way I can; you should not use silverlight if you decide to use flash.
HTH
Related
I've been reading lately about SPA and how good it is..
I was wondering if someone could tell when should I use or even better when shouldn't I use SPA as go with regular MVC
The tooling for MVC (Rails, MVC4) is much more mature. There is far more documentation focusing on the development of traditional MVC sites. Single Page Application development is HARD. JavaScript-dense applications are difficult to write and can be extremely difficult to debug.
If you want to jump into SPA, look into John Papa's video training series on Pluralsight.com - which, to my knowledge, offers the best starting point for developing SPA apps. Or study Backbone, but that's simply not for the faint (feint?) of heart.
One futher suggestion: if you're a ASP.Net developer, look into BreezeJS (http://www.breezejs.com) for data management.
This blog post gives a good overview of some of the potential issues with SPAs, along with some suggestions for workarounds.
The potential issues include:
Browsers are not the best species in memory handling and garbage collection. Specially when it comes to DOM handling. For example, elements removed from DOM are stil held in memory. If we let users to
work on DOM for a long time without a refresh, Browser might struggle
to cop up with memory issues
We should ideally reuse as much as DOM elements without disposing. But even with that approach, if the user creates thousands of reusable DOM elements as she uses the application, browser may suffer in coping up. On the other hand, the memory leaks created by bad coding practices will too pile up in a long lived DOM.
If we need the complete product suite functionality to be available as a single page application, it can be too much of JS/CSS code to be
loaded at once impacting the initial load time.
I've been reading lately about SPA and how good it is..
SPAs just invert the responsibilities of the browser-client. Traditional server-side applications do most of the work in the backend. SPAs do most of the work on the front-end.
The good thing is, generating views in the client means front-end devs can do all of their design in the browser without having to worry about touching the backend.
Decoupling View from Model (ie controllers exist on both ends) means that the data can be exposed as a REST API on the server and re-used for clients that target other platforms (ex mobile, tablet, smart tv).
Eliminating the need to refresh every time a page is loaded makes for a better user experience.
I was wondering if someone could tell when should I use or even better when shouldn't I use SPA as go with regular MVC
Switching over to building SPAs from server-side MVC architectures can be very challenging for some. Many devs who work exclusive in a server-side language may just hate having to deal with Javascript (esp devs who program exclusively in statically-typed languages).
Making SPA's work requires some url-rewriting and redirect workarounds. This may be a very confusing/harrowing experience to get working for those who don't have a lower-level understanding of the server.
Users that have Javascript off by default will not be able to load the site.
A SPA introduces a lot more load on the client, with everything running in the main context this can make the UI slow/unresponsive. There are workarounds to solve this issue in newer SPA frameworks but it's good to keep it in mind.
Writing code code for the browser is a lot different than writing code for the server. There is a lot more complexity (ex the DOM) in the browser.
The toolchain for front-end development is drastically different from what you'd find being used to develop most server-side languages. Some programmers live-and-die by their IDEs.
Fetching data dynamically via Ajax can be extremely difficult at first for some. Especially, devs who don't have a solid understanding of HTTP.
Really, it comes down to one question. Do you want to take the time to learn how to build SPAs?
Possible Duplicate:
What Web Application Framework for Delphi is recommended?
We have a Delphi 2007 desktop application which we have hosted using Citrix. Now we want to get rid of Citrix and somehow web-enable it.
I have done bit of research and found that it is possible by using the uniGUI.
http://www.unigui.com
Conclusion: Can be done, but would require a re-write and only a subset of components are supported. Serious questions remain are the monolithic application structure in a web environment.
There are two more options morfik and atozed and they also require a re-write.
I want to know if there is any other option which requires a very less re-write work and how fragile is it?
How fragile it is, is based on the quality of your code. If you have a good structured application, with business logic and data access fully separated from the GUI, it will be pretty safe, although you still have to rewrite mostly all your GUI.
If there's logic in your forms, and the code that talks to the GUI components is intwined with the code that checks your input and stores the data, then you have a big problem.
In that case, this is a great opportunity to refactor large portions of your app and do it better this time. ;)
Since there is no "silver bullet" here, it doesn't matter much which product you use. You have the same challenges with any of them. I would recommend spending a few days on a Proof-of-Concept (PoC) re-write of 2-3 typical screens. Implement the POC for each "finalist" product, and see how it works out. Keep track of how long it took for each one, things that were easier/harder, and how the end result appears to the end-user (performance, good/funny-looking, robustness, "feel").
As for the actual re-write, I would recommend the following:
Re-factor existing application to remove business logic from the UI.
Full Regression testing, and push that into production.
NOW proceed with conversion to one of the web tools.
Oops - I left out a step. Step 0: FREEZE all features/fixes. If fixes are needed to current production, they'll need to be done in a separate branch, and then rolled-up into this project later.
Note that this type of work lends itself nicely to outsourcing, as the work is straightforward and the requirements are simple. Especially if it can be delivered one form at a time, so progress, timelines, and $$$ can be measured in small chunks.
Another preliminary step is to develop a "cook book" for stripping the business logic from the existing GUI layer. It should identify naming conventions, common libraries (for code that should have been shared all along but wasn't), and should describe the conversion methodology.
AFAIK, there's not tool will convert your desktop application to web application without requiring rewrite for most of GUI Parts.
as Golez said, you will have to refactor your application, try to separate your business logic from the GUI, then you can use some tools like Intraweb to develop the GUI as web and reusing the existing business logic with it.
Another option by converting your application to n-tiers technology and warp your business logic as web services or any open technology and make your web part by any web languages such as ASP.Net or PHP.
Depending on how 'Web enabled' you want the App to be.. I use Cybele Software's (https://www.cybelesoft.com/) Thinfinity UI to extend Apps to the Web, including Database Apps.
It only requires the installation of their ThinFinity Server and one line of code added to the Proj source and you are in business.
The Apps all run on your PC.
Well perhaps I simplified it a little, but worth a look.
HTH.
Regards,
Ian
I've been learning ASP.NET MVC for about a month now and I'm certainly sold on its benefits but I realize it is not applicable to all situations.
I've read in several places that ASP.NET MVC is not ideal for data-intensive applications:
Example 1: "Data Driven Application – life would be MUCH easier using WebForms if the application is data heavy"
Example 2: Nick Berardi's book suggests that you side with Web forms if your application is "data-heavy"
Can someone clarify as to why ASP.NET MVC is ill-suited towards data-heavy applications and why Web forms are more appropriate? Also, where does one draw the line between data-heavy applications and other applications? Are we talking quantity of data (millions of records) or are we talking large data models?
I would really like this clarified as well, as I have found the exact opposite to be true, and I think stackoverflow.com is evidence of the suitability of MVC to data-driven apps.
I didn't bother reading much of the second link, but the assertions in the first are not qualified, and many of them seem wrong to me. The stated weaknesses of WebForms, though, would be enough to drive me from using it for a data-intensive app:
UI logic coupled with the code, and thus is hard to separate.
Harder to unit test, so difficult to employ TDD.
Heavy page sizes due to view state management.
The stated weaknesses of MVC are quite flimsy:
Not event driven, so maybe difficult for people who know only Asp.Net Webforms to wrap their minds around it.
Third party control library support is not that strong.
No ViewState(this is also a strength).
The first one can be seen as a plus as much as minus. The second is just wrong as MVC apps can leverage traditional server-side controls if they wish, as well as make use of the rich library of client-side controls and libraries. The third, well I don't think I even need to speak to that one...
You have to be wary when reading articles like this on the internet - they sound authoritative and comprehensive, but where is the meat? Why are the stated weaknesses an issue? It is not enough to just throw opinion out there as fact. They should be backed up with metrics, such as when using platform x over y, developers unfamiliar with either platform were able to complete an application 30% faster, or platform x resulted in 25% fewer lines of code, or fewer levels of indirection, or whatever.
The idea that RAD is a plus is another one that bears careful examination: RAD is fast until you want to do something a particular control was not designed for, and then you hit a brick wall. It is a leaky abstraction and when it fails, you are suddenly confronted with the full complexity of understanding the design framework and code of the given control. This can be quite a setback, and the source code for these controls is not always available.
Doesn't make much sense to me. They might be speculating on the difficulty of creating many models if you have lots of different types of data, or perhaps the relative difficulty of creating web forms in MVC.
However, ORMs (such as L2Sql, EF and Subsonic), model binders, and form generators (I can't find the link right now) pretty much hose those arguments.
Frankly I don't buy it.
I believe that these authors are talking about the ability to drag/drop data controls onto the page such as GridViews, FormViews, and other databound objects.
Say you have a database for your IT department, with a table for computers, a table for printers, one for software, etc. The UI for this is a very simple data management system, essentially a glorified MS Access.
Rather than writing an elegant web app, with beautiful HTML and a class library, you could simply create a quick/dirty WebForms app by dragging your data sources and controls onto the page in Visual Studio.
What language, framework, and hosting considerations should one make before starting development of a scalable web application?
The most important consideration is not to over-engineer to the point that it gets in the way of building and launching something. Analysis paralysis is the single biggest inhibitor to productivity, progress and results.
Yes, do some planning. Pick a framework. Perfection in a framework will be impossible to find because it doesn't exist, partially because you don't know what you need until you build it anyways. Chances are, if you pick something, it will be better than picking nothing.
Yes, try to pick flexible, inter-operable tools for where you see yourself going.
Yes, look for a good built-in feature set where you see yourself going in the next 6-18 Months. Trying to look beyond that is not really realistic anyways as most projects change so much anyways going towards the first release.
So, pick what you're comfortable with or what is familiar. Don't follow the crowd, do what gets you the best results, quickest, and often. Understand that you might have to change in the future. So, whatever you build now, try to use unit testing so you can re-factor if ever needed.
If what you're building is going to be super successful, it will be a great problem to have, and an easy one to work on once it's making money as you'll be able to get other talent to help you.
Share what you end up picking and why for your situation -- it helps the us learn from you too!
Don't necessarily marry yourself to one language or framework. It may be that some parts of your site work better with different languages and frameworks than others. For example, all of 37signals' sites are based on Ruby on Rails, but they recently wrote a blog post about how the underlying technology of one is actually written in Erlang now because it's much easier to do concurrency that way.
Obviously there's a level of complexity where things turn into a mishmash, but using the right tool for the job — even if that means different tools for different jobs — can simplify things.
Firstly on language, it largely doesn't matter. PHP, Java and .Net being probably the biggest three are all proven in the sense that they run some of the largest sites on the Web so don't listen to anyone who tells you one is more suited than any of the others.
Some might also put Ruby and Django/Python in this list. I have nothing against them but I'm not aware of any big (say top 50) sites using either.
Hosting considerations depend on how low you want to start but basically the order is:
Shared;
Virtual Private Server;
Dedicated.
Scalability will largely be about your application's design than any language, framework or provider. Efficient database schema, efficient delivery and use of Javascript/CSS and in-memory caching are all issues common to any language or framework.
Language - I'd recommend something with good frameworks and good testing libraries like Perl or Java.
Framework - it depends on what do you plan to do. If you start with a hosting that does not allow FastCGI, it is best to avoid such frameworks like Catalyst or Rails. That's why I love CGI::Application (primarily Perl, but ported to other languages too) - it can run as CGI, FastCGI or mod_perl. For development it can be run from it's own web server.
Hosting - nothing is better than you own server. It can be your own server, leased server or virtual server. But you can start with cheapest hosting and when you need more, you should be able to afford it.
It depends.
Start by looking at your requirements (Functional or user defined) (Non Functional - aspects that describe your desired system link text)
Next I would clarify what it means to have a scalable web application. Define it as test cases that can be clearly tested (must support X page views / second with response time < Y seconds).
Once I had those pieces in place I would look at what type of skills my development team can support (for the intial project and on going maintenance). Then find some case studies of applications out in the wild that use similar language or framework. If someone else has made a specific language / framework scale then chances are good that you can too.
Finally go out and look for some hosting providers that support your chosen language, framework and requirements.
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.