I have an xmpp/ejabberdb app that uses an external service to provide eventing features, but when this service becomes unavailable, I want to disconnect/logout all of my clients. Is this possible? How?
I got it working the way I needed. In fact, I didn't find any simple way to make my own server logout all connected users given some kind of situation, so I dug into ejabberd's code and figured out a way to do it myself.
In ejabberd_c2s.erl module, when a client logs out or it's socket is dropped for some reason, the FSM is terminated, doing all necessary clean up to maintain ejabberd's consistency.
What I had to do was just create an exported function shutdown/1 in this module that calls gen_fsm:send_all_state_event/2 sending a signal for it to terminate.
As for each connection there's one c2s process, I need to call this function for each user.
---UPDATING---
Actually there's no need to create this shutdown function, as ejabber_c2s already has the ability to process 'closed' signal, which does the same thing. So, instead of creating the shutdown function, simply doing ge_fsm:send_event(C2SPid, closed) might be enough.
---UPDATING---
To discover the user's c2s process PID I just use ejabberd_sm:get_session_pid/1 or ejabberd_sm:dirty_get_sessions_list/0 (for all sessions).
This worked fine for me, but if anyone has a better idea, please add here.
Thanks
I don't know the ejabberd specifics, but you could write a custom XMPP component which polls the external service (or listens for presence events, if it's another XMPP component), then logs out users when the service becomes unavailable.
Related
I want to understand how can I integrate VoIP for my WEB app which in my case would be a Rails app.
What I wan't to achieve is sending socket events to the front-end for each call state:
call ringing
call started
call ended
The implementation is already done but I'm not convinced if is the right architecture and the informations I found until now over the internet are poor.
I don't think that makes sense to explain how is currently done (but if needed I can provide), but starting from ruby-asterisk gem which can be used to retrieve data about an extension number what would be the correct architecture in order to retrieve continuously events from call states and send them as socket events to the WEB?
How can you determine if the call is ended?
On the overall implementation, do you see any use of redis for saving previous states of a call and then to determine the new states?
Main issue is : asterisk is PBX
Again: it is small office PBX, not all-in-one platform with API.
So correct architecture for high load is centralized hi-perfomance socket server, which support auth, response on your api calls(if any), event notification etc etc. After that you have use AMI+ dialplan to notify you server about actions on PBX.
You web app should connect to thoose server, not directly to asterisk. Only ONE connection to asterisk recommended for peformance considerations.
If you have low load - doesn't matter what you do, it likly will work ok.
Asterisk not support redis, so use of that unlikly. Use CDRs for end event.
I've got a rebus server process running on one machine and an MVC website on another. I configure the message routing in the MVC website with a local input and error queue and the destination pointing to the queue myinputqueue#BusServer and when it runs it sends the subscription message without error but nothing seems to appear on the destination queue. The receiving bus never acknowledges it or creates a subscription entry.
It's using msmq as the transport and all queues have full permissions to the Everyone group.
I'm assuming I've not configured something correctly so I hope this is the right forum to raise the question.
Appreciate any help.
Even though Everyone has access to the queues, and that sounds like there's nothing in the way of communicating freely, I'm not sure that it works that way.
In any case, I suggest you make sure your IIS app pool is runnig with some dedicated service user identity, which you can also use as the user account under which your server process is running.
With MSMQ, messages are never lost - so in your case, the subscription message is most likely sitting in an outgoing queue on the web server machine, or it might have been moved to the "Transactional dead-letter queue" which is where MSMQ ends up moving stuff that it cannot find a place for.
Could you try and take a look at the outgoing MSMQ queues and/or the transactional dead-letter queue to see if it's a user rights problem that is haunting you?
I have created a windows service which gets soem info from database and I want to notify user based on the info retreived from the DB. How can I notify user from a windows service using system tray notification? Can you please show me some sample (using IPC mechanism) to get the return value of a method used in a windows service in a system tray notification?
Thanks in advance.
There are several options such as these:
Sockets: (Not too difficult to write, has firewall problems) You can find samples for it almost everywhere.
External WinForm: (The easiest method, has security problems and might blocked by
some antivirus apps) Just create a winForm with the ability to go into
the windows notification area and then tell the service to run its
exe file.
Named Pipes: (Probably the most difficult, but it's the recommended
solution) Here is a Code Project sample.
Other tricks like: Create a hidden winform project (ShowInTask=false) and put it in StartUp. provide it with a FileSystemWatcher object and make it watch for a certain file which the service creates or deletes it to signal the winform.
How can I tell if the application my code is running in, is it in a service or an application? Why do I want to know this - I'm writing some code that is injected into the target application and that code has no way of knowing this information up front, so it has to work it out itself.
I cannot rely on any code being called from the service control manager, start, stop, or command line parameters.
I'm currently looking at GetConsoleWindow() which I hope will return NULL for a service (no console) and a window handle for any application (has a console). Not sure how valid this assumption is.
Any ideas for a better solution?
Search the current process id (GetCurrentProcessId) from the list of all running services (EnumServicesStatusEx)?
The assumption of GetConsoleWindow() is not valid.
It seems to me that you care about the context of your process more. Are you asking that if your program is running in service context or the user session? If so, use ProcessIdToSessionId() http://msdn.microsoft.com/en-us/library/aa382990%28v=VS.85%29.aspx to get your session id and you will know it.
Use WMI to query for Win32_Service instances where 'ProcessId=MyProcessid'. If there is no match, then your process is not a service.
Background on WMI app creation in C++ here.
For Windows Vista or later you can check the session id. Session 0 is reserved for services and non-interactive programs. User sessions start from 1.
Use OpenProcessToken to get the current process token. Then use CheckTokenMembership to see if the token includes the WinServiceSid well-known SID.
I am to build a web application which will accept different events from external sources and present them quickly to the user for further actions. I want to use Ruby on Rails for the web application. This project is a internal development project. I would prefer simple and easy to use solutions for rapid development over high reliable and complex systems.
What it should do
The user has the web application opened in his browser. Now an phone call comes is. The phone call is registered by a PBX monitoring daemon. In this case via the Asterisk Manager Interface. The daemon sends the available information (remote extension, local extension, call direction, channel status, start time, end time) somehow to the web application. Next the user receives a notified about the phone call event. The user now can work with this. For example by entering a summary or by matching the call to a customer profile.
The duration from the first event on the PBX (e.g. the creation of a new channel) to the popup notification in the browser should be short. Given a fast network I would like to be within two seconds. The single pieces of information about an event are created asynchronously. The local extension may be supplied separate from the remote extension. The user can enter a summary before the call has ended. The end time, new status etc. will show up on the interface as soon as one party has hung up.
The PBX monitor is just one data source. There will be more monitors like email or a request via a web form. The monitoring daemons will not necessarily run on the same host as the database or web server. I do not image the application will serve thousands of logged in users or concurrent requests soon. But from the design 200 users with maybe about the same number of events per minute should not be a scalability issue.
How should I do?
I am interested to know how you would design such an application. What technologies would you suggest? How do the daemons communicate their information? When and by whom is the data about an event stored into the main database? How does the user get notified? Should the browser receive a complete dataset on behalf of a daemon or just a short note that new data is available? Which JS library to use and how to create the necessary code on the server side?
On my research I came across a lot of possibilities: Message brokers, queue services, some rails background task solutions, HTTP Push services, XMPP and so on. Some products I am going to look into: ActiveMQ, Starling and Workling, Juggernaut and Bosh.
Maybe I am aiming too hight? If there is a simpler or easier way, like just using the XML or JSON interface of Rails, I would like to read this even more.
I hope the text is not too long :)
Thanks.
If you want to skip Java and Flash, perhaps it makes sense to use a technology in the Comet family to do the push from the server to the browser?
http://en.wikipedia.org/wiki/Comet_%28programming%29
For the sake of simplicity, for notifications from daemons to the Web browser, I'd leave Rails in the middle, create a RESTful interface to that Rails application, and have all of the daemons report to it. Then in your daemons you can do something as simple as use curl or libcurl to post the notifications. The Rails app would then be responsible for collecting the incoming notifications from the various sources and reporting them to the browser, either via JavaScript using a Comet solution or via some kind of fatter client implemented using Flash or Java.
You could approach this a number of ways but my only comment would be: Push, don't pull. For low latency it's not only quicker it's more efficient, as your server now doesn't have to handle n*clients once a second polling the db/queue. ActiveMQ is OK, but Starling will probably serve you better if you're not looking for insane levels of persistence.
You'll almost certainly end up using Flash on the client side (Juggernaut uses it last time I checked) or Java. This may be an issue for your clients (if they don't have Flash/Java installed) but for most people it's not an issue; still, a fallback mechanism onto a pull notification system might be prudent to implement.
Perhaps http://goldfishserver.com might be of some use to you. It provides a simple API to allow push notifications to your web pages. In short, when your data updates, send it (some payload data) to the Goldfish servers and your client browsers will be notified, with the same data.
Disclaimer: I am a developer working on goldfish.
The problem
There is an event - either external (or perhaps internally within your app).
Users should be notified.
One solution
I am myself facing this problem. I haven't solved it yet, but this is how I intend to do it. It may help you too:
(A) The app must learn about the event (via an exposed end point)
Expose an end point by which you app can be notified about external events.
When the end point is hit (and after authentication then users need to be notified).
(B) Notification
You can notify the user directly by changing the DOM on the current web page they are on.
You can notify users by using the Push API (but you need to make sure your browsers can target that).
All of these notification features should be able to be handled via Action Cable: (i) either by updating the DOM to notify you when a phone call comes in, or (ii) via a push notification that pops up in your browser.
Summary: use Action Cable.
(Also: why use an external service like Pusher, when you have ActionCable at your disposal? Some people say scalability, and infrastructure management. But I do not know enough to comment on these issues. )