I have business logic in one application, let's call it "server". I want to "observe" what's going on in this application using a silverlight or WPF app.
So I've figured, I will use WCF services that expose current state to my clients, and I will poll for updates on a regular basis.
It's working well, but I need some kind of two way communication, because I need to notify my clients about changes.
Is there any other way than polling?
For Silverlight, there is a PollingDuplex mode, which still results in polling, but has a somewhat easier API to work with than dealing with the polling yourself.
See this article on MSDN : http://msdn.microsoft.com/en-us/library/cc645027(VS.95).aspx
For WPF, I believe there are more efficient ways to do this, but I'm not as familiar with the full WCF stack.
http://msdn.microsoft.com/en-us/library/ms731064.aspx
Related
I have two WinForms applications that need to communicate.
I'm thinking about using WCF to establish communication between those two, but converting one of them WCF service application is not an option.
Is there a way to implement the WCF somehow or should I forget about it?
For example I thought of creating a WCF server (with Push and Pull mechanisms) that both applications could use, but I don't think it's very efficient.
Moreover, consider that the users cannot have administrative privileges, if this helps proposing other solutions.
Main idea is create an WCF service hosted in a Winform or an Console application. Than you should add the WCF service reference to your Winform applications References. Rest is simple. You may query the service in a timer say 500ms. This whole consept may help you. If you want to see an implemented example see the link below:
Have you seen: http://wcfsimplechat.codeplex.com/ . This little WCF Chat sample can help i think.
I'm an asp.net developer with very little experience in WPF. I'm looking to create a very basic application, one that would be distributed to a couple clients and allow any given client to send a basic message to all of the others running the application.
I'm not exactly sure where to start or what to look for, being that I'm new to the WPF world. Could someone point me in the direction I need? Would it involve MSMQ? I'd like to stay away from polling if possible, but what generally would I need to know to get started? Thanks.
You could take advantage of the classes in the System.Net.PeerToPeer Namespace.
I did some push notification with WPF and WCF in 2006 using the framework classes from .NET 3.0 which were deprecated by System.Net.PeerToPeer in .NET 3.5 / 4.0, but the old system worked well, so I can only assume that the new classes in the framework are even better :-)
We used push notifications for the majority of data that didn't matter if it was missed by a client, but MSMQ for sending important occasional messages that absolutely could not be lost. You don't necessarily need MSMQ though - we were running mission-critical apps which demanded it, so we played it safe.
Click here to read the MSDN Magazine article that was published to introduced the new P2P namespace in 2007.
I have a Silverlight application that uses WCF RIA Services. I'd like to be able to switch the datasource to a local store (for example, SQLite) for demo or UI testing purposes.
At which layer should I refactor my code to allow to do this? Is there a way to do this without repeating functionality already present in WCF RIA Services classes (DomainClient, Entity, etc.), or should I create the switch much higher in the abstraction and bypass all of these classes altogether?
Thanks.
The DomainClient is the hook the framework provided for implementing this kind of switch. However, I don't think I've heard of anybody taking that approach. Instead, the split is often made at the Service layer of applications designed using the MVVM pattern (discussed in this video http://channel9.msdn.com/Series/Silverlight-Firestarter/Silverlight-Firestarter-2010-Session-4-MVVM-Why-and-How-Tips-and-Patterns-using-MVVM-and-Service-Pat).
Also, you might find this thread interesting as it discusses some existing patterns that have been used to persist data to the Silverlight isolated store.
http://forums.silverlight.net/forums/p/219768/524983.aspx#524983
What's the fastest communication model for a Silverlight component communicating with a WPF component? That is, at the very least I'd like to consume an event from a Silverlight component in a WPF component.
I understand you can use WCF to build a bridge
I understand you can use Javascript to bridge from WPF -> Silverlight (and I have that working)
I understand you can use COM to go the other way (Silveright -> WPF)
However I'm looking for a tighter communication model (not using COM) - perhaps like EventAggregator (Silverlight component pubs, WPF component subs)...but I've only seen eventAggregation in WPF or Silverlight but not both at the same time.
Any ideas for creating such an eventAgg / eventBus, without using WCF, without using COM?
Open to any approaches / ideas; might be something I haven't considered.
Thanks.
Interesting challenge - could you provide a little more detail on why you need to do this?
My first question is: Are you envisioning these two apps running on the same machine, at the same time? Both are important.
If the answer is yes (same machine, both running) then you should be able to implement a solution using WCF, with the service self-hosted in the WPF app, the Silverlight client referencing it, and a cross-domain policy setup appropriately.
If the answer is yes, but not at the same time, then you'll need a third party, like a Message Bus, perhaps implemented as a Windows Service. NServiceBus comes to mind.
In any case, WCF really is the best solution for messaging in Silverlight. If you were going Silverlight app-to Silverlight app there is a mechanism for that that doesn't require WCF.
A message bus would give you the Event Aggregator functionality you're thinking of - a player who is always there to accept subscriptions and publications.
Another option (if running at the same time) is to elevate your Silverlight app to full-trust and use Sockets. See this link for more info (he provides an example that may be helpful).
I'm considering using Silverlight for a business type application which will contain probably a dozen or so screens. The screens will contain data entry forms with edit fields, grids, lookups, calendars, etc. Typical business application type screens. I want this to run in the browser but don't want to mess with HTML, JavaScript, CSS etc. Is Silverlight 3 appropriate for this type of application? Can someone build professional level business type apps with Silverlight 3?
#Randy Minder,
Glad to hear that you want to use silverlight 3 for line of business application.
I used to develop line of business applications in ASP.NET combined with javascript/AJAX. I am currently developing my first silverlight 3 line of business application and found silverlight is better in few departments. The following are the Pro/Cons observed by me PERSONALLY.
Pros
Layout/Styling(CSS)
XAML + silverlight 3 styling is very flexible and less cluttered when compared to CSS. I am not a designer and I hate having to deal with CSS. But in the case of silverlight, I really enjoyed creating the mockup,layout & styling. The end result is awesome. This is the first application that I developed has decent & consistent look & feel. I hope you will also find silverlight xaml to be easier to deal with.
Rich Interaction & Language support
I used to use Ajax, javascript for creating rich interaction experiences like populating some data dynamically when user interacts with UI. Writing some complex UI logic in Javascript is daunting. Though there are some nice javascript libraries like Jquery, I think writing UI complex logic in C#/VB.NET/F# is much easier than to write it in javascript. Dealing with rich interactive controls in silverlight is much easier than with javascript/ ajax controls. Writing server communication code with WCF or WCF RIA service is far easier than with ajax calls.
Browser compatibility
Each browser is different from another in one or the other way, like some browser supports something and others dont. Having to deal with browser differences in javascript is also a pain. Silverlight being a plugin doesn't have to deal with browser differences. No problems dealing with layout engine differences too.
Animations/multimedia
Ofcourse with line of business applications we will not use toooo much of animations/multimedia. However we can use small animations like menu popup, sliding controls, fading transitions for when data changes etc. These are very easy to implement in silverlight than with asp.net/javascript
Validation
Validation support in silverlight is awesome you can write more validation logic in less time.
Popup messages
Popup messages are very clumsy to deal in ASP.NET and sometimes I need to store some information in hidden fields to feed text for popup messages. Hidden fields are used as javascript & ASP.NET interaction components which are difficult to maintain and end up with more code.
Good separation of presentation & model
Though you can separate these layers in ASP.NET also, silverlight enforces this by design which is good. In my team there are few developers who dont want to put effort on separation of the layers. Unfortunately they are the seniors in age and decision makers. I always hate to deal with their spaghetti code. Not to say that I am a better developer than them, I always put some effort to separate the concerns and try to learn how to manage my code. ASP.NET webforms doesnt enforce separation of presentation & model by design. Where as silverlight enforces this by design and my life became easier.
Cons
Clipboard
Users are very much used to copy the content available on ASP.NET/HTML page. Most of the silverlight 3 controls doesnt support clipboard out of the box. The only control I know that supports out of the box is textbox.
Database Communication
Database communication in ASP.NET is easier & direct communication is possible. However silverlight being client side technology it doesnt have direct access to database and a necessity of creating an additional tier is mandatory. Though WCF RIA services make the development of this additional tier easier, still WCF RIA services is in beta as of now. Though I am mentioning it as disadvantage, I did not really feel it is as REAL disadvantage because creating a WCF service is not that difficult.
Client side resource usage
Though cost of hardware reduced alot,client side hardware resources are not unlimited when compared to server side. At my work place, though PC provided have decent configuration, most of the users open lot of applications simultaneously which is required to accomplish their day to day tasks. Silverlight uses client side CPU/memory. Some of my users are complaining that the application I developed is using more CPU/memory than the asp.net equivalent. So if your users have slower PCs, consider ASP.NET or design your silverlight application more carefully.
One may say installing silverlight plugin as disadvantage, I did not face the problem because my application is a intranet application and all users installed silverlight with a single email request.
These are MY experiences with silverlight 3. The only major issue I faced was clipboard support in silverlight, I hope MSFT will address this soon.
All in all, silverlight ROCKS!!! Silverlight 3 is ready for enterprise and if you can wait for few more months Silverlight 4 will be released which has even better support for line of business applications. I dont want to develop ASP.NET applications anymore, that doesnt mean that I will quit using ASP.NET, I will use it only when necessary. I fell in love with silverlight and for a good reason. Designing part of the website is the one I used to hate most but with silverlight designing became one of my favorites.
I hope that silverlight 3 will help you in your decision making.
Absolutely. Take a look at this post about the Vancouver Olympics:
http://csharperimage.jeremylikness.com/2010/02/vancouver-olympics-howd-we-do-that.html
That's just one example of a business application in the "real world" being used to drive a massively complex operation. I posted that just to draw attention to the "business" side of Silverlight, but be sure to click the link to the original post to see the other partners and contributions to the project.
I've been building enterprise/business applications with Silverlight for over a year now. So the answer is an emphatic "Yes, you can" and "Yes, it's been done" and "Yes, it's been done on a large scale with large companies, and very successfully."
I agree #Jeremy. Make sure to use RIA Services with Silverlight , You will get a very manageable/maintainable application. Even one more benefit is that you can make the SL app Out of browser too.