The pricing for Azure SignalR Service is based on Concurrent Connections.
However, I can't find the definition of a Concurrent connection.
I have an ASP.Net Core MVC Web Application. I understand that the server application connection to the Azure SignalR Service is one connection. Each client (browser) that connects to my web app is another connection. But are these considered concurrent connections? Or just open connections sitting there waiting for a message to be sent?
I'm hoping that the count of concurrent connections is a count of connections that are actively sending a message. Is that the case?
Ok so I figured out that a Concurrent connection is any connection to the SignalR Service!
I ran through the quickstart tutorial here
And then used the Azure Metric as I connected various clients to the chat room, and this is what I found:
After starting the app in debug mode, it seems the server immediately uses 5 connections. Then, as I open the url in various browser tabs, a new Client connection is established. As expected, the 16th browser tab does not establish a SignalR connection (Because I am on the Free SignalR Service tier, which has a limit of 20 connections.)
Related
we are facing an issue with WCF service hosted in a Windows service with net.tcp binding.
After some time it closes all connection (we see it in real time with TCPView). We noticed this behavior because in the client application log we find errors of TCP connection refused 10061. When all connection are close it starts to accept new conections. All firewall and antivirus has been disabled. RAM and CPU are ok.
What can I look for?
Thanks
I deployed my java web application on Bluemix Dedicated environment and use it with Cloudant Dedicated NoSql DB. In this DB i tried to return 60k documents and server returned
500 Error: Failed to establish a backside connection
to me. So i'm wondering about connection timeout in Bluemix, there're posts where people claim that Bluemix resets a network connection in 120 if there's no response received. Is it possible to change this setting, or maybe someone knows how to solve such problem.
P.S. When I deploy it on my computer then it works fine, but of course it takes some time. Particularly this case may be solved using cloudant pagination, but i develop service for scheduling REST-calls and if bluemix reset all connections after 2 minutes i'll have a big problems with it.
Not sure which Bluemix Dedicated you are using, but the timeout is typically global. Paging would work and I thinking a websocket based approach would work as well.
-r
I'm trying to build a web app that operates in real-time via a push model. I've used sockets in the past to achieve this, just not in a distributed service. My question is: Given that the host that receives the updated information (via Amazon
SQS) is not necessarily the host that the necessarily the host that
the web browser has a socket connection open with, How do we find the socket connection and then push the data.
Thanks
In Postgres, is there a one-to-one relationship between a client and a connection? In other word, is a client always one connection and no client can open more than one connection?
For example, when Postgres says:
org.postgresql.util.PSQLException: FATAL: sorry, too many clients already.
is that equivalent to "too many connections already"?
Also, as far as I understand, Postgres uses one process for each client. So does this mean that each process is used for one connection only?
Refer - https://www.postgresql.org/docs/9.6/static/connect-estab.html
PostgreSQL is implemented using a simple "process per user"
client/server model. In this model there is one client process
connected to exactly one server process. As we do not know ahead of
time how many connections will be made, we have to use a master
process that spawns a new server process every time a connection is
requested.
So yes, one server process serves one connection.
You can have as many connections from a single client (machine, application) as the server can manage. The server can support a given number of connections, whether or not these come from different clients (machine, application) is irrelevant to the server.
The connection is made to the postmaster process that is listening on the port that PG is configured to listen to (5432 by default). When a connection is established (after authentication), the server spawns a process which is used exclusively by a single client. That client can make multiple connections to the same server, for instance to connect to different databases, or the same database using different credentials, etc.
When deploying a web application running on a traditional web server, you usually restart the web server after the code updates. Due to the nature of HTTP, this is not a problem for the users. On the next request they will get the latest updates.
But what about a WebSocket server? If I restart or kill the old process all connected users will get disconnected. So my question is, what kind of strategy have you used to deploy a WebSocket server smoothly?
You're right, every connected user will be disconnected if the server restarts.
I think the less bad solution is to tell to the client to reconnect in the onClose method of the client.
WebSockets is just a transport mechanism. Libraries like socket.io exist to build on that transport -- and provide heartbeats, browser fallbacks, graceful reconnects and handle other edge-cases found in real-time applications.
In our WebSocket-enabled application, socket.io is central to ensuring our continuous deployment setup doesn't break users' active socket connections.
If clients are connected directly to sever that does all sockets networking and application logic, then yes - they will be disconnected, due to TCP layer that holds connection.
If you have gateway that clients will be connecting to, and that gateway application is running on another server, but will communicate and forward messages to logical server, then logical server will send them back and gateway will send back to client responses. With such infrastructure, you have to implement stacking of packets on gateway until it will re-establish connection with logical server. Logical server might notify gateway server before restart. That way client will have connection, it will just wont receive any responses.
Or you can implement on client side reconnection.
With HTTP, every time you navigate away, browser actually is creating socket connection to server, transmits all data and closes it (in most cases). And then all website data is local, until you navigate away.
With WebSockets it is continuous connection, and there is no reconnection on requests. Thats why you have to implement simple mechanics when WebSockets getting closing event, you will try to reconnect periodically on client side.
It is more based on your specific needs.