sending data to clients from a server in vb - vb.net

Actually I have created a chat application is it possible to send data to particular client only?

It should be possible, we don't know how you implemented the chat application but there's no reason you can't send to a single client. In fact that's probably what you're doing already, just to every client (in a loop or something).

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Transferring a Back-to-back call, how to provide status to client

In our application we have a back-to-back-connection between an operator (client) and a caller, via an ucma-application we built. Now we want to transfer the caller to another operator or number.
This transfer is attended, so we want to keep the call in the client at least until the transfer is completed.
The client application tells the ucma-application to do the transfer. As such, the server makes a transfer on the leg from ucma -> caller. In this scenario, the leg from ucma to the client application remains intact, but we want to receive information about this transfer so that we can show the transfer status in the client application. If the transfer fails, it should also be clear to the operator (it should also be on hold during the time of the transfer, and continue to be on hold even after transfer failed).
Which is the correct way to do this in UCMA?
It's hard to give you advice as there are multiple ways to do what you want depending on what you need to achieve.
I think the main problem is that you are doing the transfer in the middle, you can't tell the Lync Client to go on "hold". Because of this, you can only put the call on hold from the point of view of UMCA application. This means that if you will have to provide your own UI to unhold the call if it fails, maybe from your own Client Application GUI.
What you could do is write a Lync Client SDK controlled Lync Client application. If you have a Lync Client SDK controlled Lync Client, you could remote control the Lync Client to do the transfer, that way you get the standard Lync Client failed transfer UI. If you do this, what is the point of the UCMA application?
If you have to do it from the UCMA point of view, you could:
Provide the UI in your only Client Application (I would think no nice) including controlling the hold status on a failure
Lync Client SDK controlled Lync Client to put the call on Hold that way it's the standard Lync Client way to unhold on failure, then the only need to worry about the display of a failed transfer. Maybe display something in your client application, maybe a send a in call IM from the UCMA application?
See if the Lync Client support BoardWork Extensions (specifically the Remote Control Hold Event Package). If it does then you can remotely put the call on hold, most likely though that it doesn't :(

WCF server controlling client (windows forms)

I'm building an application, it's easy and what I want to do is the following. I want a brainless client and all the work should be done on the server. So I want a way to change windows forms in my server application and not on the client itself.
So when I have an application like blackjack the user presses hit then the hit function on the server get called, he will calculate everything, send the result back to the client and then the client updates it buttons and GUI (like displaying cards, and so on).
Now how do you do this in WCF? I know how to call remote function but I can't get the windows forms part to work (can I add this in the contract, and how?)
Thanks!
Your client should handle all of its own UI. Your service shouldn't have anything to do with the UI.
Instead of having the service handle the UI, just have it send messages back to the client and let the client figure out which UI elements to show or not based on the messages.
So, when the server calculates some result, like BLACKJACK!, it'll send a message indicating that back to the client which will then show the proper UI elements.
Make sense?

Receiving SMS over SMPP

I have a project coming up where I need to send and receive messages through a specific mobile operator, which only provides an SMPP interface. The whole project will be a hosted website. I have already read quite a lot, but I do not yet quite understand what is actually needed from my side to use the protocol.
Should my application try to maintain a constant connection to the smpp?
Can I simply connect, send a message and then disconnect?
Are receiving messages based on push or pull?
Thanks for the help.
SMPP is a peer-to-peer protocol. That should mean that SMS Gateway (your side) and SMSC (your mobile operator) need to have a proper bind/connection established. Even when there are no SMS or DLRs to send/receive, there is a continous exchange of smpp PDU (enquire_link/enquire-link_resp) that ensure that the bind is established.
In detail, if you send an enquire_link PDU and you get no response (enquire_link_resp) the bind is broken. Your sms won't be delivered (will remain enqueued in your gateway store), and you won't receive MOs (incoming sms) or DLRs (delivery report). To re-establish the connection you should re-initiate the connection.
So, my answer would be that you need a constant connection to SMSC.
You are stating you want to receive messages, as a result at least a bind_receiver is needed. Because you don't know when messages are going to come in, you will have to be constantly connected, rather than disconnecting after each event.
With regards to your question about "push or pull" this depends on how you solve the first problem. If you can build a solution that is constantly connected, the result will be a push (the carrier will push it to you as soon as they receive the message). If (for some reason) you cannot maintain a constant connection, you'll end up building a pull mechanism. You'll connect to the carrier ever X seconds to see if they have a message waiting for you.
I do need to highlight 2 pitfalls though:
A number of carriers in the world, do not store or even accept messages if you are not connected, therefore, depending on which carrier you interact with, you might be forced to use a continuous connection.
Most carriers do not allow you to open and close connections in quick succession. Once you disconnect, you can not reconnect for a time frame of X seconds.
Therefore a constant connection is really the way to go. Alternatively, you can look into a company like Nexmo, which will provide you with a HTTP Call every time a message arrives.
I'm not sure which language your developing your application in, but if you use any of the popular languages (Java, PHP, Perl) there are modules out there that handle basic SMPP Connectivity for you. A quick google search for your language and "SMPP Client" will give you a list of references.

iPhone GameKit: Clients detect other clients

I'm trying to set up a client-server architecture. I have one GKSession configured as a server, and two others as clients.
When either client uses the sendData:toAllPeers:WithDataMode:error method, it sends it not only to the server but to the other client.
I guess I could use the display name to exclude clients, so client data only goes to the server, but I'm not quite following why this is happening.
My server explicitly accepts a connection, via acceptConnectionFromPeer:error: But my client isn't accepting anything from anybody, it seems to be just silently finding the other client.
Should this be happening? I understand in a peer-peer setup you'd want peers to just find others; but in client-server, this seems a little weird.
Any clarification or advice would be greatly appreciated.
While a client cannot explicitly connect to another client, but the method sendData:toPeers:withDataMode:error: should allows you to send data directly from one client to another given that you have the correct peerId.

Offline client and messages to azure

I'm playing around with windows azure and I would like to build a clouded server application that receives messages from many different clients, such as mobile and desktop.
I would like to build the client so that they work while in "offline-mode", i.e. I would like the client to build up a local queue of messages that are sent to the azure server as soon as they get online.
Can I accomplish this using wcf and/or azure queing mechanism, so that I don't have to worry about whether the client is online or offline when I write the code?
You won't need queuing in the cloud to accomplish this. For the client app to be "offline enabled" you need to do queuing on the client. For this there are many options, a local database, xml files, etc. Whenever the app senses network availability you can upload your queue to Azure. And yes, you can use WCF for that.
For the client queue/sync stuff you could take a look at the Sync Framework.
I haven't found a great need for the queue so far. Maybe it's just that I'm not seeing it in my app view. Could also be that the data you can store in the queue is minimal. You basically store short text strings (like record ids), and then you have to do something with the ID when you pull it from the queue, such as look it up, delete it, whatever.
In my app, I didn't use the queue at all, just as Peter suggests. I wrote directly to table storage (accessed via it's REST interface using StorageClient) from the client. If you want to look at a concrete example, take a look at http://www.netalerts.mobi/traffic. Like you, I wanted to learn Azure so I built a small web site.
There's a worker_role that wakes up every 60 seconds. Using one thread, it retrieves any new data from it's source (screen scraping a web page). New entries are stored directly in table storage (no need for a queue). Another thread deletes entries in table storage that are older than a specified threshold (there's no issue with running multiple threads against table storage). And then I'm working on the third thread which is designed to send notifications to handheld devices.
The app itself is a web_role, obviously.