Develop Reference

UCMA recording app

I've installed a MSPL script to redirect INVITE audio messages to the UCMA sip address
I'm currently writing a UCMA app for Skype for Business to:
receive incoming calls
accept the call
create a conference call
add a trusted participant to the conference
create a recording instance on the trusted participant audio flow to record the conversation
The last thing I need to do is add the To caller URI to the conference call.
I've tried to invite the new participant into the conference using the code examples from this article, but I get an exception saying there are no AvailableMediaTypes in the conversation.
public static async void InviteToConference(string destinationUri)
{
//Create a new conversation for the application endpoint.
_toConversation = new Conversation(_server.ApplicationEndPoint);
var conferenceInviteSettings = new ConferenceInvitationSettings();
conferenceInviteSettings.ConferenceUri = _conferenceUri;
ConferenceInvitation invitation = new ConferenceInvitation(_toConversation, conferenceInviteSettings);
try
{
await invitation.DeliverAsync(destinationUri);
}
catch (InvalidOperationException)
{
// Conversation was terminated while trying to add participant.
}
}
Can someone please show me what I need to do to add / invite a participant into a conference call?
It would be even better if someone could show me how to record a Skype for Business call without the need to create a conference, as a conference can't be forwarded.

Your code looks like the old way (UCMA 3) of doing it. Have you tried this.
e.g.
McuDialOutOptions mcuDialOutOptions = new McuDialOutOptions();
mcuDialOutOptions.ParticipantUri = "sip:alice#contoso.com";
mcuDialOutOptions.ParticipantDisplayName = "Alice";
mcuDialOutOptions.PreferredLanguage = CultureInfo.GetCultureInfo("en-us");
conversation.ConferenceSession.AudioVideoMcuSession.BeginDialOut("tel:+14255551234", mcuDialOutOptions, dialOutCallback, state);
Using this sort of method to record very specific and low traffic should be fine but when you start to scale it up then you are going to hit all sorts of problems.
As for how to do it without a conference:
There is no way to do it fully with the supplied Microsoft API's.
What you have to do is implement, buy or use open source libraries for the following pieces:
sniff network packets
decode RTP/SRTP streams
decode the audio and/or video codecs used between the callers
encode streams into your desired format and save somewhere
To get access to the SRTP streams encryption setup and to figure out what the dynamic payload types for the audio/video codecs used, you also need to know the SDP offered and answered between the calling parties. You also need access to the SIP traffic to determine the calling parties to know who called who. This can be a lot more trouble than what it seems...
To get the SIP/SDP information there are two options that I know of:
Skype/Lync Server SDK (MSPL / Server Application) to see most of the SIP traffic. This is what I've used to implement a recording solution.
Skype/Lync SDN SDK - I haven't used this API but it seems to give access to the SDP so it should work.
If you get all these peices into place then the next problem is you can only "record" (basically "sniff") what you can see. If you can't see the RTP/SRTP traffic you can't record the calls.
So you need to have the sniffer part of the recording software on areas of the network that see the traffic you want to record. For example if you wish to record all PSTN calls, you can have a network spanning port off the Skype mediation servers.
If you wish to record ALL calls, then that gets a lot harder. You most likely need to either:
Force all media trafic to go through a known place (like the Edge server) and put sniffers on the that network.
Have lots of sniffers in strategic areas of the network to capture most RTP/SRTP traffic.
The problems with the above solutions are:
Forcing all the traffic through one point can cause performance issues (like you will see with your conference setup) once load starts to increase. Also forcing external (edge server users) and/or federated calls through this one point can cause a problems. Think edger server user calls to edge server users where the media traffic may not even go into your network at all but live only on the internet. Forcing the trafficing into your network can cause performance issues.
When not forcing all the traffic through one point, you may never be see all skype user to skype user calls depending on your network setup. Calls between Edge server skype users are even more of a problem as the media traffic may not even enter your network at all.
On top of all that there are the general problems of storage management (recording after a while will start taking up a large amount of disk space) and call recording management (e.g. searching for a specific call) and user security around these recordings to deal with. I'm sure I'm missing a lot but those are the basics.
If recording in not going to be a core component, you could just buy a 3rd party call recording solution that supports Lync/Skype.

Unable to seek/replay video (.ogv) files served from http server [C#]

ISSUE:
Video player (native player in webkit based browser) is not giving option to replay and I cannot seek video while playing it. Once played, I have to refresh page to play it again.
If I give a web url for ogv video in my html page, same player works fine (replays and seek is successful).
Hence I suspect issue with my algorithm of serving files (especially .ogv files).
What I am doing:
I have an HTTP fileserver (completely in C#, using .Net framework classes - HttpListenerContext, HttpListenerRequest, HttpListenerResponse, etc). This server is serving files (of all types and extensions - text, video, audio, images) to clients. All files are available on server which are requested by clients.
Algorithm to serve files from server:
Server gets the file name from URL.
Reads the complete file in a buffer(byte[] array) (using File.ReadAllBytes(file_path_on_server)),
Array is assigned to HttpListenerResponse.OutputStream to return the file (contents) to client.
Corresponding HttpListenerResponse.ContentType (MimeType) and HttpListenerResponse.ContentLength64 is assigned (size of array).
Response header is added as "no-cache".
HttpListenerResponse.ContentEncoding is UTF8.
Close response object to send it to client.
This works fine and files are reaching clients for processing including video files (.ogv) but video is not seekable/replayable in player.
Already tried
Tried removing assignment of HttpListenerResponse.ContentEncoding to UTF8.

It seems that you server returns the file the same way as if it's just downloaded, so seek/replay most likely will not be available until the whole file is loaded. If you want to support true video streaming you need another server-side implementation. Live Streaming within IIS Media Services may help you to support Apple HLS Streaming or similar (depending on your player), also i saw somewhere an IIS extension/module that supports http pseudo streaming with seeking for some video formats.

How to resend args to an app if its already running and have it refresh with those args

I have an issue. I'd have a video player that takes in simple parameters as a c# form app. As an experiment to better understand programming, I'd like to have only one instance of the app running and have it refresh with the new args if the open command is given. I could program it so that when it gets the signal, to refreshVideo() or something like that.
Pseudo example:
//app is started from cmd line
//open app for first time
vidViewer.exe("lotr.avi", "44:44");
//keep instance open but have it refresh with new movie
vidViewer.exe("star_wars.avi", "22:32")
As it stands right now a new app with embedded video player will open, so I could have 100 open flicks if I passed it enough args. I'd just like to keep it at one.
Can provide more info if needed.
Thanks all,
Kevin

My suggestion would be to design your application such that, when launched, it would attempt to acquire a system resource that is mutually exclusive (meaning that only the first instance would succeed). Since, in your scenario, you will also require a means of interprocess communication (to transmit the name and start-time of new videos), you may use the same mechanism for achieving this.
You could, for example, use a self-hosted WCF service, bound to a fixed TCP port, that each application instance attempts to register upon being started. Due to the way ports work, only the first instance will succeed; subsequent instances would fail with a “port already in use” exception.
If an instance manages to register the WCF service, then you may assume it to be the “principal” instance and proceed to play the video on it. It should, however, listen for incoming messages from the WCF service and update the video being played accordingly (see below).
If an instance finds that the port is already in use, it should assume that another instance is already running. It would then initialize a WCF client that sends the name and start-time of the new video to be played to the WCF service. Finally, it should terminate itself without displaying any window, assuming that the principal instance will take care of playing its video.

How To Do a Server To Server File Transfer without any user interaction?

In my scenario, users are able to upload zip files to a.example.com
I would love to create a "daemon" which in specified time intervals will move-transfer any zip files uploaded by the users from a.example.com to b.example.com
From the info i gathered so far,
The daemon will be an .ashx generic handler.
The daemon will be triggered at the specified time intervals via a plesk cron job
The daemon (thanks to SLaks) will consist of two FtpWebRequest's (One for reading and one for writing).
So the question is how could i implement step 3?
Do i have to read into to a memory() array the whole file and try to write that in b.example.com ?
How could i write the info i read to b.example.com?
Could i perform reading and writing of the file at the same time?
No i am not asking for the full code, i just can figure out, how could i perform reading and writing on the fly, without user interaction.
I mean i could download the file locally from a.example.com and upload it at b.example.com but that is not the point.

Here is another solution:
Let ASP.Net in server A receive the file as a regular file upload and store it in directory XXX
Have a windows service in server A that checks directory XXX for new files.
Let the window service upload the file to server B using HttpWebRequest
Let server B receive the file using a regular ASP.Net file upload page.
Links:
File upload example (ASP.Net): http://msdn.microsoft.com/en-us/library/aa479405.aspx
Building a windows service: http://www.codeproject.com/KB/system/WindowsService.aspx
Uploading files using HttpWebRequest: Upload files with HTTPWebrequest (multipart/form-data)
Problems you gotto solve:
How to determine which files to upload to server B. I would use Directory.GetFiles in a Timer to find new files instead of using a FileSystemWatcher. You need to be able to check if a file have been uploaded previously (delete it, rename it, check DB or whatever suits your needs).
Authentication on server B, so that only you can upload files to it.

To answer your questions - yes you can read and write the files at the same time.
You can open an FTPWebRequest to ServerA and a FTPWebRequest to ServerB. On the FTPWebRequest to serverA you would request the file, and get the ResponseStream. Once you have the ResponseStream, you would read a chunk of bytes at a time, and write that chunck of bytes to the serverB RequestStream.
The only memory you would be using would be the byte[] buffer in your read/write loop. Just keep in mind though that the underlying implementation of FTPWebRequest will download the complete FTP file before returning the response stream.
Similarly, you cannot send your FTPWebRequest to upload the new file until all bytes have been written. In effect, the operations will happen synchronously. You will call GetResponse which won't return until the full file is available, and only then can you 'upload' the new file.
References:
FTPWebRequest

Something you have to take into consideration is that a long running web requests (your .ashx generic handler) may be killed when the AppDomain refreshes. Therefore you have to implement some sort of atomic transaction logic in your code, and you should handle sudden disconnects and incomplete FTP transfers if you go that way.
Did you have a look at Windows Azure before? This cloud platform supports distributed file system, and has built-in atomic transactions. Plus it scales nicely, should your service grow fast.

I would make it pretty simple. The client program uploads the file to server A. This can be done very easily in C# with an FtpWebRequest.
http://msdn.microsoft.com/en-us/library/ms229715.aspx
I would then have a service on server A that monitors the directory where files are uploaded. When a file is uploaded to that directory or on certain intervals it simply copies files over to server B. Again this can be done via Ftp or other means if they're on the same network.

you need some listener on the target domain, ftp server running there, and on the client side you will use System.Net.WebClient and UploadFile or UploadFileAsync to send the file. is that what you are asking?

It sounds like you don't really need a webservice or handler. All you need is a program that will, at regular intervals, open up an FTP connection to the other server and move the files. This can be done by any .NET program with the System.WebClient library, doesn't have to be a "web app". This other program could be a service, which could handle its own timing, or a simple app run by your cron job. If you need this to go two ways, for instance if the two servers are mirrors, you simply have the same app on the second box doing the same thing to upload files over to the first.

If both machines are in the same domain, couldn't you just do file replication at the OS level?
DFS

set up keys if you are using linux based systems:
http://compdottech.blogspot.com/2007/10/unix-login-without-password-setting.html
Once you have the keys working, you can copy the file from system A to system B by writing regular shell scripts that would not need any user interactions.

Custom API requirement

We are currently working on an API for an existing system.
It basically wraps some web-requests as an easy-to-use library that 3rd party companies should be able to use with our product.
As part of the API, there is an event mechanism where the server can call back to the client via a constantly-running socket connection.
To minimize load on the server, we want to only have one connection per computer. Currently there is a socket open per process, and that could eventually cause load problems if you had multiple applications using the API.
So my question is: if we want to deploy our API as a single standalone assembly, what is the best way to fix our problem?
A couple options we thought of:
Write an out of process COM object (don't know if that works in .Net)
Include a second exe file that would be required for events, it would have to single-instance itself, and open a named pipe or something to communicate through multiple processes
Extract this exe file from an embedded resource and execute it
None of those really seem ideal.
Any better ideas?

Do you mean something like Net.TCP port sharing?

You could fix the client-side port while opening your socket, say 45534. Since one port can be opened by only one process, only one process at a time would be able to open socket connection to the server.

Well, there are many ways to solve this as expressed in all the answers and comments, but may be the simpler way you can use is just have global status store in a place accesible for all the users of the current machine (may be you might have various users logged-in on the machine) where you store WHO has the right to have this open. Something like a "lock" as is used to be called. That store can be a field in a local or intranet database, a simple file, or whatever. That way you don't need to build or distribute extra binaries.

When a client connects to your server you create a new thread to handle him (not a process). You can store his IP address in a static dictionary (shared between all threads).
Something like:
static Dictionary<string, TcpClient> clients = new Dictionary<string, TcpClient>();
//This method is executed in a thread
void ProcessRequest(TcpClient client)
{
string ip = null;
//TODO: get client IP address
lock (clients)
{
...
if (clients.ContainsKey(ip))
{
//TODO: Deny connection
return;
}
else
{
clients.Add(ip, client);
}
}
//TODO: Answer the client
}
//TODO: Delete client from list on disconnection

The best solution we've come up with is to create a windows service that opens up a named pipe to manage multiple client processes through one socket connection to the server.
Then our API will be able to detect if the service is running/installed and fall back to creating it's own connection for the client otherwise.
3rd parties can decide if they want to bundle the service with their product or not, but core applications from our system will have it installed.
I will mark this as the answer in a few days if no one has a better option. I was hoping there was a way to execute our assembly as a new process, but all roads to do this do not seem very reliable.