Solved

Raise an event from the web service to a client

Posted on 2009-04-05
3
264 Views
Last Modified: 2012-06-21
Is this possible?

The client and web service were both created using VB.NET 2008 Framework 3.5

Our client application does all of its transactions with the server via a web service. We have a new messaging function which needs to be implemented and in order to receive new messages we need to either poll the server at regular intervals in order to check for new messages, or we need the web server to be able to tell the client application when there is a new message.

The second option is clearly ideal. So the question is how can it be done?
0
Comment
Question by:tfsln
3 Comments
 
LVL 15

Accepted Solution

by:
Solar_Flare earned 500 total points
ID: 24073969
You cannot do your preferred option with web services. A services sits there waiting to be consumed by a client, and has no way making a connection to the client. In order to acheive this you would need to modify the client to accept incoming tcp connections, and then have the server know the address of each client and initiate a tcp connection from the code-behind to the client when required, and then any firewalls in between are going to be a problem.


The only reasonable way is to have the client poll for new messages.
0
 

Author Comment

by:tfsln
ID: 24073975
So how do instant message applications work? Or any other application which display notifications like that? Do they constantly poll servers to check for new messages/items?

Having the server know the address of each client is not a problem, because i could send that information to the server each time a user logs in. I guess the only problem would be firewalls like you say.
0
 
LVL 15

Expert Comment

by:oobayly
ID: 24077130
IM applications tend to use their own protocol and not http (even if they use tcp 80). Their connections tend to stay open so that data can be pushed back and forth, unlike http which was designed as a stateless protocol: the connections were supposed to be closed after a page was requested. Only with http 1.1 were connections defaulted to remain open as opening connections tend to be expensive.
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Today I had a very interesting conundrum that had to get solved quickly. Needless to say, it wasn't resolved quickly because when we needed it we were very rushed, but as soon as the conference call was over and I took a step back I saw the correct …
A long time ago (May 2011), I have written an article showing you how to create a DLL using Visual Studio 2005 to be hosted in SQL Server 2005. That was valid at that time and it is still valid if you are still using these versions. You can still re…
This Micro Tutorial will give you a basic overview how to record your screen with Microsoft Expression Encoder. This program is still free and open for the public to download. This will be demonstrated using Microsoft Expression Encoder 4.
Both in life and business – not all partnerships are created equal. As the demand for cloud services increases, so do the number of self-proclaimed cloud partners. Asking the right questions up front in the partnership, will enable both parties …

862 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

25 Experts available now in Live!

Get 1:1 Help Now