I am trying to find the best solution to build the application at work.
1) My client has a web service, I need to have a automatically process to pull data from client web service, store in a database. The data will be displayed in a aspnet MVC web application. Once new data coming in, I want to notify the current user (something like a badge)
Question 1: I have two ideas for the process to pull data from client's web service,
A)I create a WCF service, and host it as a Windows Service
B)Create a console application and get the schedule task to run the console application
Question 2: I am thinking to use SignalR to indicate users of the new data, but in the backend how do get SignalR to check the data changes?
Thanks very much guys
Regards
Question 1: I have two ideas for the process to pull data from
client's web service, A)I create a WCF service, and host it as a
Windows Service B)Create a console application and get the schedule
task to run the console application
Did you mean WCF client? To pull data from client's web service you need a WCF client not a service? The rest looks ok to me here.
Question 2: I am thinking to use SignalR to indicate users of the new
data, but in the backend how do get SignalR to check the data changes?
SignalR is just a mean to send notifications to clients. The way you check for updates depends on the nature of the notification. So you would better elaborate on this part to get a better advice. A common way to do it is to have a notifications log table/queue which you can check for updates, process them and send to the clients. Don't forget to remove or mark processed notification in the table.
Alternatively, you can host SignalR in a windows service with a WCF client and a timer to pull data from web services. You can notify your web users directly from the windows service. Please see this article Tutorial: SignalR Self-Host
Hope it help!
Related
We have an ASP.NET MVC web app that we have installed in several clients/domains (more than 100). This web app works with MS SQL database running in a Windows server. All the domains are in the same service and running in separate databases in the same MS SQL server.
Each client can create events for their users. We are talking some days one client could have more than 200 events.
We need to create a Window service to be running on the server where all the clients are to send, every few hours, reminder emails of each event for each client.
As I explained before each client has its own database and there is a common database with all the clients information and their database names.
What the service has to do is check, for each client, the events they have and send the corresponding emails.
We don't know if is better to have one service to go through all the clients or have a service per client. If we have just one service we would have to run it , for example, every 6 hours sending those emails.
In case we have a service per client we would need to create the service from the asp.net web app, would it be possible?
What is the best approach for this?
You can use SQL Server Integration Service to do this job. All you need to write a SSIS package and schedule it.
On each execution of this package you can check data and send emails accordingly.
I hope this idea will help.
We're planning on adding SignalR to several differnet web applications. The applications are targeted different aspects of an order. When something happens to an order, all users working with the order across all web applications should be notitfied.
Changes to an order are availible asa message on a servicebus.
We could implement the following logic in all web applications:
Subscribe to a topic (one subscription per webapp)
OnMessage -> Send orderId to hub
Hub would notify clients working on the orderId
Question is: Could we implement all this common functionality in a separate application, and all web apps would reference the same signalr scripts?
All applications live on the same domain, and it would give us a lot of benefit not having to implement signalr in every app.
Good idea, or am I missing something important here?
Edit: Put in other words: I have WebAppA, WebAppB and WebAppC all without SignalR. I'm asking if its possible to create a WebappD that talks to clients in WebApp A,B,C
Second Solution is very good. it will move signalr load (espcially memory) from your main web apps to WebAppD(signalr web app). And all your main web apps will not be dependent to signalr.
Drawbacks: You don't have any authentication on WebAppD. Because clients are authenticated on the other WebApps. You should let the WebAppD knows about orderId. That's why, you should send message to server (WebAppD) from clients(Javascript).
Because of enable cross domain settings, anyone can send message to server. Even they don't need to be connected WebAppA,WebAppB or WebAppC. Even if you solve this problem (virtual path etc), Someone is connected but not authenticated on WebAppA,WebAppB,WebAppC can sends message. Because WebAppD just get the message and it doesn't know this client is authenticated or not so it will serve this message to all others. In Short: Someone can send fake messages to other clients.
So you should share your authentication like this (or some other logic) between your web app and signalr webapp.
Other than this I couldn't see any drawback.
I am new to web development but I have a project done in VB6, it is a real time send and receive sms application. It uses a GSM modem connected to the server. My company asked me to make a web based version of my application, using ASP.NET MVC.
So I studied MVC about a month ago, created basic CRUD apps, read about SignalR but I don't want to start up a project that I am not confident if its feasible or not. So my question is, is this project possible with the said technology? (MVC, SignalR, and a GSM Modem)
If it is, can you point me somewhere I could start reading for maybe you know a similar project that can guide me through.
And if it is not, can you suggest me the appropriate tech to use for this project to be feasible? (I prefer ASP.NET MVC)
A little detail about the functionality of the project:
Has User Authentication - this user will have a simple "SMS box" type of thing which will update like a chatbox if an SMS is received in the GSM modem and this user can reply and use the GSM to send the SMS back to the sender.
IF anyone could help me, guide me, point me to some reading materials to make this project it would be greatly appreciated. Please post if you need clarifications and further explanation. Thanks!
User,
There are many ways to achieve this, so I will explain a method that worked for me a while back doing exactly this.
Based on the information provided, I will assume that you have a windows desktop app, that can already talk to the modem and perform various functions.
Trying to perform that same tasks in a web application can be a hard path to go down, what I opted for was rather simple in my opinion. You really have two separate problems, one is getting the received messages to the web application and the other getting the web application to send messages to the modem.
For handling received messages, I created a simple web api in the web application and defined a post method that is able to receive a sms object. You will need to provide the url for this call to your code that resides in your modem project, which I would convert to a windows service, if it is not already. Then when your code fires when the modem has received a sms, you simply create a object, serialize it to xml or json and then call the post method in your web api. This will give you the chance to use SignalR to notify clients or whatever else you might need to do. This is honestly is the simple part and you have the "real-time" handling ability now for receive.
For sending, there again where many options, I opted for database polling from the code inside the windows service, so when a user wants to reply or send a message, the message gets stored in a table in a database, from where the service code will pick it up and send it, once sent it will mark a field in the table as sent and possibly add a date and time as to when this happened. Again your service code could call another method on your web api, that will notify your app, that a message was sent and again you could notify the end user.
As for database polling, there are various methods, you could simply run some code every minute or some configurable value to see if there are any unsent messages.
You could use SqlDependency and handle the events in real time, you would register an event against the table where messages to be sent will be inserted into and when this happens, your service code will receive a real time event which can be handled.
You could also in the windows service, create a service, even a self hosted web api again, which can be called from your web application when it wants to send an email.
I did various implementations based on client requirements, but for me hosting either a wcf service or web api in the windows service project, proved to be the best in my opinion. You then simply have a configuration section in your web application, and provide the service address, or uri for the post method.
I hope that I have given you enough ideas to get a starting point for your project.
I have a smart grid system where multiple hardware devices are sending raw sensor data to an Azure Queue. Each device sends a single data packet once every minute. Multiple Worker Roles process the data packets on the queue and push the data to Table Storage. I have a Web Role which holds the application for users to view their device data and a host of other alerts and messages relating to their smart energy system. At the moment the web application just uses ajax polling at one minute intervals to get the latest data updates and any other messages and alerts. Instead of using ajax 'pulling', I'd like to use SignalR instead and 'push' the updates from the cloud when they become available. I'm not sure on what the overall architecture might look like.
So far I have added a SignalR Hub to my Web Role, just to see if I could do that. And it works fine. However, how do I trigger updates from this Hub when there are changes in Table Storage? Should I host the Hub with the Worker Roles that process the raw data, and then make a cross-domain SignalR connection from the web app (client)? Can I even associate an endpoint with a Worker Role? If I have many Worker Roles wouldn't I only be able to connect to one of them, and therefore miss data updates from other Worker Roles?
Perhaps I should create a separate Web Role to host the SignalR hub, but then how do I communicate the changes from the Worker Roles that process the raw data to the hub? Maybe I need to include another Azure Queue that takes messages from the Worker Roles regarding data updates, alerts, and any other messaging, and that queue is processed by the SignalR server. However, would this approach be scalable? If I have multiple instances of the SignalR server processing the message queue(s), would they share the same end point and be aware of all the client connections across the instances? Or maybe the Worker Roles themselves connect as clients to the SignalR server and the messages forwarded from there to the clients.
Is SignalR even the right approach to take if data is being generated at a predictable rate of once every minute for each device. Maybe for updates of this regular data ajax 'pulling' is the best approach, and I should just be using SignalR for the infrequent alerts and messages, although, again, how do I communicate these events from the Worker Roles to the SignalR server?
What overall architecture would suit my needs here?
EDIT 06-09-2014 Half the problem solved
I came across http://www.asp.net/signalr/overview/signalr-20/performance-and-scaling/scaleout-with-windows-azure-service-bus which seems to be exactly what I am after. This deals with the problem of multiple Hub server (Web Role) instances. Now I just need a SignalR client library that can run on the Worker Roles so that they can notify the Hub that new data is available, and the Hub class can then be enhanced to route the new data to the appropriate connected web clients.
EDIT 06-10-2014 A workable solution found
I have added an answer to my question of "What architecture". I thought a quick summary of my setup might be useful. I have many remote devices associated with different users posting real-time data to Azure Queues. The data posted to these queues are parsed and saved to Table Storage, by a number of Worker Roles. Web Roles provide the MVC5 web application for the users (clients) to log on and review their data. I wanted a mechanism by which when new data was posted, any connected clients would receive a real-time notification (and data tables and charts in the client apps could be updated accordingly). SignalR with Service Bus scaleout proved to be the answer.
The first part of the solution I needed was to deploy a SignalR hub that the clients could connect to, to receive any notifications sent. I couldn't use the basic SignalR solution as the MVC5 web app is hosted on a Web Role that will likely have more than one instance - the problem was how to keep all these instances synced so that whatever instance a client was connected to they'd still receive the notifications. SignalR scaleout with Azure Service Bus proved to be the answer to that part of the problem. Details of how to set this up can be found at: http://www.asp.net/signalr/overview/signalr-20/performance-and-scaling/scaleout-with-windows-azure-service-bus - it was VERY easy to setup.
The second part of the problem was how to generate the notifications originating from the Worker Roles (my queue data processors). First I needed to be able to host OWIN in my worker roles - the instructions provided at http://www.asp.net/aspnet/overview/owin-and-katana/host-owin-in-an-azure-worker-role were more than sufficient. Once this was done I created an empty Hub instance with the same name as the one deployed on my Web Roles (it was empty because I didn't expect to have an clients connected to it directly), and changed the Startup class to:
public class Startup
{
public void Configuration(IAppBuilder app)
{
String connectionString = "[Service Bus Connection String]";
GlobalHost.DependencyResolver.UseServiceBus(connectionString, "[App Name]");
app.MapSignalR();
}
}
With this in place if I want to send a notification out to the clients, from the Worker Roles, I do something like:
var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
context.Clients.All.clientMethod("[Message]");
What really happens is that a copy of the message gets pushed to the backplane (Service Bus) and is picked up by the Web Roles and pushed out to the connected clients. In reality I will check who is online (in the Web Role Hub instance I override the OnConnected method to save the user's connection id in their profile which is stored in Table Storage), and only create notifications that are associated with those users to reduce SignalR traffic.
I'm currently hosting 2 webstites (clientportal and admin), in windows azure websites.
I'm going to introduce SignalR right now, to get rid of javascript polling. What I need, is when an admin send a broadcast message on the admin site, all the active client should be receive it. Now, the clien polls the webserver all the time, when an ajax poll receives, the webserver check for new messages in the database.
What would be the best way, to notify the client webserver from the admin webserver? WebApi is ok for this? Or are there any simple way?
From the point of view of Azure Websites and SignalR, it is transparent who is the Client and who is the Admin. This is an implementation detail, and thus, there are many ways to do it.
SignalR is split in two parts: The javascript library, and the .NET library that you use to create your "Hub". One way to accomplish what you are trying to do is to implement the Hub functionality in your Admin back-end using the .NET side of SignalR and ASP.NET Web API; and use the javascript side of SignalR to subscribe and listen for notifications on the Client side.
Another way to do it is to create a third component, just for the SignalR Hub, independent of both the Client and the Admin websites. In this scenario both the Admin and the Client would subscribe to the Hub, but only the Admin would push, and the Client would listen.
You can find many working examples on the internet. This is one of them: http://msdn.microsoft.com/en-us/magazine/hh965663.aspx
I hope this answers your questions.