Would a change in a reported property in a module on IoT Edge generate an event that can be 'observed' by an application via IoT Hub APIs?
You can use the IoT Hub Service API (REST) to "poll" the current state of your module twin.
If you want to be notified in real time, you can setup a route to have your twin change events be sent to Blob storage, Event Hub, Service bus…
Polling and setting up a route are definitively the 2 ways to go on the back-end side of things. You can also find more details on back-end operations in the docs.
Related
I am currently writing tests for an existing project based on azure functions. The project uses signalr to send live update messages to the clients.
For my tests I am currently using a signalr instance, that is running in the cloud, but I need to replace it by a "local" instance on the system, that is running the tests, so i can be 100% sure, that the signalr message is coming from my test session.
Does anybody have an idea, how to get a signalr-server running in a docker container for my tests (i need a connection string i can provide for the azure functions app)?
I could not find anything online. I am sure I am not the only one, who wants to test if signalr messages are send correctly and i would prefer not to implement the signalr-server myself.
The bindings available in Azure Functions are for the Azure SignalR Service not SignalR itself, so there is no way unfortunately to test this locally.
You could simply instead just create a test Azure SignalR Service instance and use that instead.
I didn't find any way how to achieve this, so i created a repo with a small mock service for the SignalR service. I hope I am allowed to post such stuff here.
My repo and my docker image
Feel free to use / fork it. I am not sure if I will ever find any time to maintain it.
We are reading the LwM2M 2m spec for a college assignment simulation and trying to implement client and server requests.
Finding it hard to understand few details. Documentation is limited on it. We were told a requirement was to configure multiple clients. Does that mean each end point will have its own object ids according to LwM2M? What will be unique for each client? What we understood was each client has several objects like location, device, access control, security etc. Is there any good documentation out there or can someone give us a pointer for basic hierarchy of LwM2M?
LwM2M server registers client devices by uniqued endpoint name. To understand the lwm2m server and client flow better, you should play this demo sand box from leshan lwm2m
https://leshan.eclipseprojects.io/#/clients
You can read this to understand more about API in lwM2M
https://www.win.tue.nl/~lrahman/iot_2016/tutorial/LeshanTutorial_2016_v2.pdf
At the moment i still only have about 2 months of experience in UI5. i developed a little sample-app, used sap gateway builder to pass my requests to sap backend.
Now my employer asked me to research the possibility to access two different backends (one sap, one nonsap) via odata from the same app. After a little reading and thinking i came to the conclusion that it would be best to access both backends from a single gateway.
Since ive already worked with sap gateway, i wonder if there is a way to access nonsap backends with sap gateway? Are the better options?
Or is my current approach complete wrong and i should think about a whole other way?
It depends on your approach and the non-sap-system:
Is the non-sap-system accesible via Webservices? Then use second data model (e.g. JSON/ODATA) within SAPUI5 by loading data via webservices after initial loadup of your application.
Is the non-sap-system connected to SAP? E.g. via RFC or another technology, then you can read data from the other system during calling your initial Gateway service and simply call your RFC function module in your method.
From my opinion you will not achieve an 'easy' way to read both via one single SAP NetWeaver Gateway.
Not sure why you would want to access a non-SAP oData service via SAP Gateway. On the other hand you may want a router of some sort so that all services are exposed on the same network location and then incoming requests are routed to the appropriate backend for action.
You may also want to "mash-up" the SAP and non-SAP services into some sort of new service. In that case maybe look to some of the API management tools like Apigee to help you achieve that.
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 want to use Azure service bus in my iOS app to communicate with server i have went through the below link. its pointing to C#.Need suggestions to work on iOS.
http://azure.microsoft.com/en-us/documentation/articles/service-bus-dotnet-how-to-use-relay/#next_steps
You may want to consider using WebHttpRelayBinding for your service so you can hit the Azure endpoint using HTTP / HTTPS.
WCF supports both RESTfull and classic SOAP style messaging but using lightweight json requests in a RESTfull service would be better from a mobile app.
read the following article for details. but you don't need to write custom autostarter if you are using IIS 7.5 or greater with appfabric, since it has autostart functionality in built.
http://msdn.microsoft.com/en-us/library/hh966775.aspx
if you don't need request-response messaging pattern then you can also consider service bus queues for persistence, and your on-premise process can pull and process the messages at its own pace.