How to write an offline version of an AJAX/ASP.NET web application

Question

We have a web application that uses AJAX to talk to an ASP.NET web service. We would like to write another version that can be used offline. We need to be able to re-use our existing code as much as possible. What approaches should we consider?

The app is currently using XmlHttpRequest to get dynamic data from the server. Obviously the offline version will not be able to talk to the server, but it does need to talk to something! I'm sure installing IIS or Cassini on the client would work, but I was hoping for a simpler solution. Is there no other way for JavaScript to talk to some external code?

Not sure what you're looking for. AJAX itself implies you're going to be communicating with a web server. By "offline" do you mean you don't want communication with a server or you want it to run internally only (not on the Internet)? — Kon
– Kon, Commented Feb 3, 2009 at 14:56
He might just mean "It's got lots of neat Javascript and DHTML." — BobbyShaftoe
– BobbyShaftoe, Commented Feb 3, 2009 at 15:05

Apiwat · Accepted Answer · 2009-02-24 06:54:24Z

3

There are plenty offline web apps nowaday. It simply evolve from AJAX.

For example:

WoaS (wiki on a stick / stickwiki), Tiddly Wiki,

Google doc and Gmail is going to be offline.

You don't need a webserver to run these webapps in offline mode. Just store the required data, scripts on the client side (usually as XML).

answered Feb 24, 2009 at 6:54

Apiwat

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Rine le Comte · Accepted Answer · 2009-02-03 14:59:17Z

1

One of the possibilities would be to use Cassini. This is a web server that acts as a host for the ASP.Net runtime. You can host Cassini in a Windows application or a Windows Service. In this scenario you do not have to rewrite the web app and the web service.

Most other solutions do require a rewrite of both your web app and your web service. Depending on the way you have written the existing app you can reuse more or less code.

answered Feb 3, 2009 at 14:59

Rine le Comte

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Rebecca · Accepted Answer · 2011-01-25 08:49:27Z

1

Have you considered HTML5 with application cache and offline storage?

answered Jan 25, 2011 at 8:49

Rebecca

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Mark Brittingham · Accepted Answer · 2009-02-03 15:00:06Z

0

If you hope to create an "offline" version of your package your biggest issue by far will be the need to install your site into a local copy of IIS (registering a virtual directory, etc.). I pursued this briefly a few years ago and gave up in frustration. It can be done: a number of software vendors such as DevExpress do this so you have local copies of their demonstration projects. Indeed, I was able to do this. The problem was the classic "it works on my computer" syndrome. There was simply no way to guarantee that most of my end-users had anywhere near the technical proficiency to make this work.

Thus, I would strongly recommend that you not pursue this path unless you have very technically proficient users and a huge support staff.

But there is one more very important question: did you abstract all data access code to a DAL? If not, then you have a lot of work to do in managing data access as well.

Update: user "Rine" has recommended Cassini. I just wanted to let you know that I pursued Cassini and another 3rd-party web server as well. I think that there are licensing issues with Cassini but may be wrong - it has been awhile. However, I do distinctly remember running into barrier after barrier with this approach and very little documentation to help me out.

answered Feb 3, 2009 at 15:00

Mark Brittingham

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Rine le Comte Over a year ago

VS uses a ASP.Net Dev Web Server to run web apps locally during development. I believe this web server is based on Cassini. See msdn.microsoft.com/en-us/library/58wxa9w5(VS.80).aspx for details about the local ASP.Net web service

Calmarius · Accepted Answer · 2009-02-03 15:01:41Z

0

if you want a web application run offline, you need a webserver (IIS for ASP) bound to the localhost (127.0.0.1) address. After this so can access your web application by typing http://127.0.0.1/ in your web browser the same way as you do online.

answered Feb 3, 2009 at 15:01

Calmarius

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Quassnoi · Accepted Answer · 2009-02-03 15:08:56Z

0

If your AJAX relies on XMLHttpRequest's, you can:

Make the static versions of XML's you get over XMLHttpRequest and put then into a folder on disk.
Rewrite your XMLHttpRequest URL's so that they point to files on disk.
Rewrite your XMLHttpRequest's so that they don't check status (it's always 0 for the file:// protocol.

All JScript works on file:// pages as well as on http:// ones.

Of course it's not the best way to develop static pages, but it may save you some time on rewriting.

answered Feb 3, 2009 at 15:08

Quassnoi

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thanikkal · Accepted Answer · 2011-05-23 11:15:50Z

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I havent come across any framework specifically built for asp.net like the ones available for PHP or RoR. Here is a good article by Steven to get you started with HTML 5 and ASP.Net Creating HTML 5 Offline application

answered May 23, 2011 at 11:15

thanikkal

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AndreLung · Accepted Answer · 2012-11-16 13:16:41Z

Obviously the offline version will not be able to talk to the server, but it does need to talk to something!

Enter HTML5 LocalStorage. It works like a database and enables you to put data on your client. Indeed you have to rework parts of your code in javascript and transmit it to the client, but then it would work offline.

Local Storage works like this: - Setter: window.localStorage.setItem(KEY, VALUE) - Getter: window.localStorage.getItem(KEY) - Remove: window.localStorage.removeItem(KEY)

To get the main page working offline you need to create a manifest. This is used to store complete sites on the client. Please refer to this for more information about manifests: http://diveintohtml5.info/offline.html

Sergio · Accepted Answer · 2009-02-03 14:57:48Z

-1

You want to build a web application to work offline?? It can't be done.

You could split the interface code from the rest (in diferent dlls) and create a windows application to mimic the behaviour of your web application. This way you have 2 distinct user interfaces but the same code for business rules and data access.

I don't really see any other way...

answered Feb 3, 2009 at 14:57

Sergio

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dano Over a year ago

I've seen it done with DOJO.. though i'm not sure of the details enough to answer this question

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