There is a server application (ASP.NET Core (gRPC service)) and a client application running on another PC (WPF).
One of the functions of the gRPC service is to send screenshots to the client application, but it has to be run as a Windows service, so I can't get screenshots directly from the service to the client application.
Question: how to implement an "agent" application running on a remote computer where the service is, but in a user session to get screenshots through it and then pass them to the client?
As I understand it is possible to do it with the help of IPC, but I can't understand the details of implementation, how can I call from gRPC service to the agent to make a screenshot, return the result (as an array of bytes) to the service and it sends it to the client...
Related
I have some questions regarding SignalR Core on the server side;
My server is written in ASP.NET Core, and it uses SignalR for sending notifications to users. The server uses Controllers with endpoints that clients interact with.
1) Can I host the entire thing in Azure App Service and add the SignalR service to it? Or would it be better to split the SignalR code out to its own server, which is called from the "main" server when needed?
2) The SignalR Service has an option for "Serverless", which according to documentation doesn't support clients calling any server RPCs when in said mode. Could I run this thing in Serverless mode as I'm only using the sockets for sending notifications to the clients. Or is it reserved for Azure functions?
3) Is there a way to get the number of connections for a user in a SignalR hub? I would like to send a push message to the user if he doesn't have any connections to the server. If not - what is the recommended way of handling this? I was thinking of adding a singleton service that keeps count, but am unsure if this would work at scale, especially with the SignalR service.
Thanks.
1) Better use the Azure SignalR.
2) Use it with the hub.
3) If you use Azure SignalR, you can just see it from the portal. In the code, whenever you use Azure SignalR or not, you can save the user Id in some var and count the connections. If you have multiple hubs and servers, you need to do more (if using redis-backplane for example).
I am creating a web app. I want to create a listening service (TCP) that listens continuously and updates web page according to that.
A Windows service or a WCF service?
At the end I just want a background service that listens on a socket continuously and update data in database. and when database is updated I will use signal r to show that in my page.
Right now I am trying with WCF but I am wondering if it can be done with Windows service also. And right now this application will work on LAN. But in the future, it can also be in the cloud.
First of all, it is important to understand that a Windows service and a WCF service are not the same.
A Windows service is a specialized executable that runs in the background on Windows.
A WCF service is a specialized piece of code that exposes some functionality through a well-defined endpoint. It does not run on its own, but instead must be hosted by some parent process, like IIS, a desktop application, or even a Windows service.
In thinking about the problem you've described, I suppose the most fundamental question to ask is whether or not you have control over the data that will be received via the TCP connection. WCF is built on the notion of the ABCs (Address, Binding, and Contract), all of which have to match in order to facilitate data exchange between WCF endpoints. For example, if you wish to expose a WCF endpoint via IIS that accepts TCP connections from some remote WCF endpoint, the remote WCF endpoint needs to send data to your IIS-hosted WCF endpoint using the agreed-upon data contract. Absent that, WCF will not work. So, if you cannot define the data contract to be used between WCF endpoints, then you'll need to find another option. An option that will work is to open a TCP listener within a Windows service, process the data as it is received, update your database, and listen for more data.
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By way of example, I work on a project that has a front-end desktop application that communicates with a back-end Windows service. We build both the application and the Windows service, so we have full control over the data exchange between the two processes. At one point in time, we used WCF as the mechanism for data exchange. The Windows service would host a WCF service that exposed a NetNamedPipeBinding, which we later on changed to NetTcpBinding to get around some system administration issues. The application would then create its own endpoint to communicate with the WCF service being hosted within the Windows service.
This worked fine.
As our system got more mature, we needed to start sending more and more information from the Windows service to the application. If I recall correctly, I believe we experimented with streaming within WCF and concluded that the overhead was not something we could tolerate. So, we used WCF to exchange commands and status information between the application and the Windows service, but we simultaneously used a TCP socket connection to stream the data from the Windows service to the application.
This worked fine.
When we got a chance to update the Windows service software, we decided that it would be better to have a single communication mechanism between the Windows service and the application. So, we replaced WCF altogether with a TCP socket connection that uses a homegrown messaging protocol to exchange information in both directions - application to Windows service and Windows service to application.
This works fine and is the approach we've used for a couple of years now.
HTH
I have an ASP.NET Core MVC application, that i want to connect it to POS ( Point of sale) device, and send payable price to pos and then pos send back me the result.
I want to run these operations on client system. how can i send data to ports of client system?
Before I had the same problem. your web application can't communicate with the port directly.
To do that you have to do the following :
1-Create a windows service project
2-Host a web Api in windows service (Web API Self-Hosting Using Windows Service)
That way your web application can call web api hosted in windows service, because web api is listening to the incoming requests. in web api, you can communicate with your desired port directly and send the result to the client.
Finally, to use this feature in your web application you have to prepare a batch file(it runs your windows service) of your windows service project and put it in the download section of your website.
if any user wants to use POS( Point of sale) device have to install the bat file
I am in a stage of using SignalR in my project and i don't understand when to use Self hosted option and when we should not use. As a example if I am willing to host my web application in server farm,
There will be separate hosting servers
Separate SignalR hubs in each IIS server
If we want to broadcast message into each client, how this is working in SignalR
The idea with SignalR running in multiple instances is that clients connected on instance A cannot get messages from clients connected to instance B.
(SignalR scaleout documentation)
However, when you scale out, clients can get routed to different
servers. A client that is connected to one server will not receive
messages sent from another server.
The solution to this is using a backplane - everytime a server recieves a message, it forwards it to all other servers. You can do this using Azure Service Bus, Redis or SQL.
The way I see, you use the self host option when you either don't want the full IIS running (because you have some lightweight operations that don't require all IIS heaviness) or you don't want a web server at all (for example you want to add real-time functionality to an already existing let's say forms application, or in any other process).
Be sure to read the documentation for self-hosting SignalR and decide whether you actually need to self host SignalR.
If you are developing a web application under IIS, I don't see any reason why you would want to self-host SignalR.
Hope this helps. Best of luck!
Help needed please
What's is the best WebSocket client library for a .net 4.5 on windows web application hosted on windows 2008 servers to connect to a remote server web socket.
The scenario is: our web application will use a web socket to connect to a server WebSocket on a third party infrastructure. Our client WebSocket will connect and send some commands and read the responses where we can identify the information needed. So there is no interaction from the user or browser its just in the code. e.g. user clicks a button and we go and get some data, and give a message dependant on the response.
so for example our client will connect to the third party socket and pass the users car registration number and send a tell me the car details and the server socket will return the data like: make, model, year etc... so we can then display that to the user.
Has anyone used this library with some good success? http://www.nuget.org/packages/WebSocket4Net
I'm hoping someone here can provide the best approach for doing this with some tried and tested solutions. I have been thinking about a web API that handles all the socket stuff in our client so i can call it and let it handle the close connection etc.