We need to load test aspnetcore signalR application. I saw about crank but that
seems to help only with aspnet signalR. Can someone help me with this.
Most probably you need a load testing tool which supports WebSocket protocol as this is what SignalR will be doing by default.
It could be also Server Sent Events, Forever Frame or Long Polling so you need to clarify the NFRs and identify which protocols are in scope and what are the requirements which need to be tested.
Depending on your skills you can go for:
Gatling which has support of WebSocket, but you will need to do some programming in Scala
Apache JMeter which supports WebSocket via the plugin, JMeter allows you to create tests using simple GUI. You will be able to also test Long Polling and Server Sent Events using JMeter, check out How to Load Test Async Requests with JMeter for more details.
I am trying to develop a cross application model/view scheme using Qt. What I mean attempting is to have:
Data: SQL Server
Model: Server Application
View/Controller: Client Application
This is for security reasons so that the Client App does not communicate directly with the server. Instead the communication between the model and the data server is handled via proxy Server App which runs on the same server as the database. Communication between the latter two is easy since Qt has the classes to handle it already and they are relatively easy to sub-class.
The problem for me is how to establish the connection between the model (based in the remote Server App) and the view (in local Client App).
I will present my ideas I gathered from researching the topic if it is the right direction but I would really appreciate some guidance. So first I will establish the network socket-based connection between the two apps. But what then? Is it possible to simply "link" the model in the Server App in the Client App as if they were part of the same app? Or should there be the model in the Client App as well and the connection would be used for synchronization between the two models? Or something different?
Thanks for help!
You definitly will have to implement some kind of protocoll. There is no benefit in security if you just link the complete model from server to client. More you will have a local copy in your applications cache for repesenting the data. You need to define what to sync and when to check for new data or send data back to the server. After that start implementing the most basic protocoll options and start sending some data across. On top of that start implementing any more features you need.
is there a way for a server to push some data to a client, wirelessly and seamlessly, which may be Windows(Phone), iPhone, Mac, or Android device, without any OS integration?
If so, what's the best design pattern to do this, and what are the best technologies to go about this?
Push technology is simply a methodology of the server initiating the transfer of data, rather than the client asking the server for it.
Apple makes push technology relatively easy to use by providing such functionality built-in on the OS. As well as Android through the Google Cloud Messaging for Android. Windows, however, does not.
Apple push notifications and Google's messaging for Android is seemingly magical and/or functionality that the OS needs to handle; however, this isn't necessarily the case. The advantage of having it "integrated" in the OS, is the same as having a framework handle the functionality for you.
Speaking in technical terms, push technology is a long-lived connection from the client to the server that accepts messages. These messages would be considered pushed messages, since the client did not make an individual request for them.
The main thing to keep in mind when implementing push technology yourself, is that the client is in charge of keeping that long-lived connection alive as much as possible. Because client IP addresses can change between disconnects, servers are not guaranteed that a client's address will be persistent across disconnects. Moreover, clients can be connected from behind a firewall, making it impossible for a server to reach the client.
For comparison, pull technology is the more traditional process of a client connecting to a server and requesting data.
Your best bet for Apple iOS will be using their push notification service.
For Android devices you should use the Google Cloud Messaging for Android. Alternatively, you can create your own background service to handle the messaging; here's a guide.
For Windows (desktop at least), you will have to create your own service to perform such duty. Here's an MSDN guide explaining how to create a Windows Service using Visual Studio (VB and C#). There might be frameworks already built that handle such messaging on Windows, however, I don't know of any.
Use WebSocket (with or without socket.io).
In the future, you could use WebRTC.
With Websockets, the setup is really simple. The client (a user agent, like a browser or a WebView) connects to the Websocket server, over http(s) (less problems with firewalls) and that's it. There's a bidirectional socket with an event-based API.
If by "OS integration" you mean "write special code for each platform" then the answer is no.
As you mentioned, you would like file system access, and background processing. That combination is not available in a cross-platform way at this moment.
If by "OS integration" you meant "without having to wait for apple/google/ms to provide the ability" then the answer is yes/maybe.
All the popular platforms have Push notifications and background processing support, as long as you code it the way each particular platform expects it.
But file system access will be limited to what restrictions the platform places on you. For instance in ios and win8(phone) there is no wy to write or read a file outside of your own apps private file structure. For security reasons, you cannot access the file system of other apps.
UPDATE:
The general pattern here is to release an app for every platform you want to support.
The app will register itself with its respective platform's push notification service.
You will write generic server side code to accept the data you want to push to all your client devices. Then you will invoke the respective push API's for each platform you support, causing the client devices to wake up and trigger the app that you provided to respond.
When the app opens, you get the app to contact your server and download the full data "the push notification being just the wakeup call for your app"
This way you can easily tell how which of your devices have received the data.
Each platform specific app must save the data to its own local storage and provide a way for the data to be shared via the methods supported by its respective platform.
On IOS it can be as simple as supporting the "Open In.." paradigm.
On W8Phone, you'll have to publish the data via one of the available "sharing contracts"
And so forth for every platform you want to support.
This is the general pattern at the moment. There are some caveats. On IOS, the app will nt automatically start when a push notification is received. This means your app will only download the whole of the data when the app is opened by the user.
A mobile app also cannot generally run indefinitely in the background. This means that once the app is started, you have a limited window for push notifications to be automatically processed by your app. After the allowed "background time". The app will close and any push notifications beep on the device, but wont open the app until the user taps on one of the notifications or opens the app directly.
Technically you could use XMPP Libraries, it is meant for implementing chat system (msn, gtalk, facebook chat, etc...) but this could work well as a push message system because it is opensource and well built to handle all the cases you never thought of. Also you could host your own server and send push message that way...
Why not use a webservice? In my previous project I used webservice to deliver data from mysql database. The webservice I used was nusoap. On the client side I used kSoap library for Android. Hope this helps.
if you want to receive and send real time communication between a server and client (irrespective of the device or OS), i would highly recommend you use XMPP technology because it is designed for the sort of things you're asking for.
The Extensible Messaging and Presence Protocol (XMPP) is an application profile of the Extensible Markup Language [XML] that enables the near-real-time exchange of structured yet extensible data between any two or more network entities. The core features of XMPP defined in [XMPP‑CORE] provide the building blocks for many types of near-real-time applications, which can be layered on top of the core by sending application-specific data qualified by particular XML namespaces.
http://xmpp.org/rfcs/rfc6121.html#intro - that is the latest RFC which will give you a good starting point.
I have a client/server application, where the client side is written in Flex/Air, and the server side in Scala.
The client side uses a local SQLite database that I would like to generate on the server side (it is small, so it can be retrieved via http when needed).
The frequency of updates is low: more or less one per day. The complication is that the database uses the Air extensions to SQLite, so it has to be generated by an Air application.
I have thought of two possible approaches:
Write a small server program in Air, and trigger it from my Scala application via
sockets. Data would be passed to the Air application in the http body.
Execute the Air server program from the Scala application whenever I need the updates to be made. Data would be passed via a file (I don't think an Air application can read stdin).
I am more inclined for the second option, since it would require less admin work (no need to check if the Air side of the server is up). However, I am not sure about the ability of Air to run as a "console" application (I don't like the cumbersome idea of creating a temporary file to pass data).
Has anybody had a similar problem before?
I need to find the most efficient way to communicate from an asp.net web server and a windows C++ application. The windows application does not have any permission to access the database of the asp.net web server.
When the user presses a button, that action with some bytes should be received by the C++ application.
In return, after processing the data on the C++ application, it will send back the result to the web server.
The only way I can think of at the moment is as following:
The asp.net web server will have two web service methods:
the C++ application will call that web service for a method for an interval. if there is a change, then the C++ application will process.
after the C++ application finished its process, it will call a method on that web service to inform about the result.
Any other ways to solve this kind of communication?
Thanks in advance.
If the C++ Application is also on Windows, named pipes would be a good solution. They can be configured to be durable so they can queue messages if either side is not ready to receive the message and they are quite easy to use. They basically look like files that you can read or write from and the data appears on the other side of the "pipe".
Take a look at the documentation (C++) here: http://msdn.microsoft.com/en-us/library/aa365781(v=VS.85).aspx
On the ASP.NET side you would use .NET API's. Here's a nice example to get you started: http://msdn.microsoft.com/en-us/library/bb546085.aspx (This example includes both client and server code.)
Named pipes would be a great solution if the C++ application is located in the same physical server as the ASP.NET application. In that case the OS would be just moving memory between processes for you so it could be very quick.
Additionally, I would configure the C++ Application as a Windows Service so it's always available and can be restarted when the server it's running on is restarted. If keeping it running is very important you could integrate Performance Counters and then have your ops team monitor the counters to make sure it is operating within expected thresholds.
The C++ application can also make a simple GET or POST request with enough information that the webserver can handle in case you don't want to expose a webservice.
You could use network sockets. It's been a long time since I have done anything with them so I can't be much help. Research Winsock (aka Windows Sockets API).
You could use WCF services and connect to them using your C++ client. You will have to research consuming WCF services from C++ client.
As #parapura suggested you could use simple HTTPRequest get & post methods. You could create your own http handler for these request to customize the response.
As you suggested you could use simple web services.