I am implementing google smart home actions for my device. The device is a camera with the action.devices.traits.CameraStream. I want to know what is the best way to respond to the action.devices.commands.GetCameraStream command asynchronously.
Currently, once my server receives this command, it needs to notify the device and wait for the device to start streaming. Then the server can respond to google with the cameraStreamAccessUrl. This is not ideal because the server is being blocked and exactly how it knows the device has started streaming is a bit tricky. I am wondering if there is a better way to achieve this, for example, the server can respond immediately with some sort of deferred response and have the device tell google what the cameraStreamAccessUrl is.
Is this possible? Thanks for your help!
It sounds like you're trying to find something like follow-up responses to asynchronously notify the stream has started. Unfortunately, CameraStream does not currently support follow-up responses, but you could file a feature request on the public tracker.
Related
My application allows a user to enter a URL of an article he/she wishes to analyze. It goes through our API gateway to reach the correct services engaged in this process. The analysis takes between 5 and 30 seconds depending on the article's word count.
For now, my reactjs client sends the request to the API and waits for 5 to 30 seconds to receive the response. Is there a better way to handle this such as enqueuing the job and let the API ping the client (reactjs frontend) once it has been done?
Server-sent Events (SSEs) allow your server to push new information to your browser, and hence look ideal to me for this purpose. They work over HTTP and there is good support for all browsers except for IE.
So the new process could look as follows:
Client send request to server, which initiates the lookup and potentially responds with the topic the browser needs to subscribe to (in case that's unique per lookup)
Server does its thing and sends updates as it processes new content. See how the beauty of this is that you could inform your client about partial updates.
If SSEs is not an option to you, you could leverage good old Websockets for bi-directional communication, but for such a simple endeavor, it might be too much technology to solve the problem.
A third alternative, especially if you are talking amongst services (no web or mobile clients on the other side) is to use web-hooks, so that the interested party would expose and listen on a specific endpoint, that the publisher (the server that does the processing) would write updates to.
Hope this is useful.
I'm dabbling with using PubNub for various parts of my app. I'm using their AngularJS library for this.
Right now, I'm just testing it for doing "analytics". Basically, I want to track ever more a user makes in the app - buttons pressed, states navigated to, etc. So, I track actions and publish on a channel.
It all works great - when the user is online. However, when offline, I lose all this tracking. I was sort of hoping that PubNub client would automatically queue all the publish requests. It does not seem to do this.
So, I'm thinking I'll have a service to collect all publish requests and put them in a queue if the device is offline. Once the device is back online, I'll publish any queued requests.
Is this the best approach? Does anyone have a better suggestion? Does PubNub already have this ability and I'm just not finding it?
Yes, currently, this is the best way to achieve this.
There are different scenarios for queuing / retrying, for example -- depending on the content of the message (eg expiration/timeliness of the message), and depending on the reason (no internet, channel permissions) you may want to re-queue/retry some and not others, etc.
So if you can implement your own retry logic custom to your use case, thats ideal. We may provide more productized options on this moving forward...
geremy
I've been following the HTML5rocks webRTC guide and I have the Javascript set up as described, however the guide is not clear on how to receive a channelToken, roomKey, and User ID. The guide says,
"Note that values used in the JavaScript, such as the room variable and
the token used by openChannel(), are provided by the Google App Engine
app itself: take a look at the index.html template in the repository
to see what values are added."
Unfortunately the link provided is no good and I'm left with very little information regarding the most essential step in this process. The guide isn't clear about whether or not the Google App Engine is a necessary component and I don't see why it should be. I have searched the web in an attempt to find a more useful source, but I was unsuccessful. I also took a look at the webRTC Demo(https://apprtc.appspot[dot]com), that too was no help seeing that the channel information is generated server side. I feel like I should just be able to make a simple http request to some Google server and then run from there. Any information regarding my problem would be much appreciated.
Apologies: the code for this example has been moved to here.
(Been meaning to update the article, but haven't had a chance...)
The apprtc.appspot example uses the Channel API on App Engine for signaling, but there are lots of other ways to do this. Signaling mechanisms are not defined by the WebRTC spec. (Note that signaling, which is accomplished via a signaling service, is the exchange of network and media metadata in order to set up a WebRTC 'call': the actual data is communicated directly between peers.)
We ran a codelab at Google I/O, which describes from start to finish how to build a video chat application that uses Socket.io on Node.js for signaling (it's very simple!) You might want to try that instead.
I got an assignment to do and for that I could use any www technology like HTML, JavaScript, PHP etc. I'm really sorry to say that I haven't studied any of these technologies. Therefore I took few tutorials and skimmed through them searching for answers.
I found solutions for many problems but one problem yet unsolved. It is this:
I want two clients to communicate through a server for this assignment. One send a message, server processes it and forwards it to the next.
None of PHP tutorials showed me anyway of doing this. All of them talked of communication between one client with a server.
Please help. Show me a way to do this. Thanks.
Currently, without reverting to cutting-edge (and possibly hacky/unreliable) techniques, your PHP server cannot initiate communications with a page you've already loaded into a web browser. This is a result of the way the HTTP protocol works.
One way to solve this would be polling on the "receiving" end for data. Something like a publish-subscribe pattern.
One way to do this would be:
One client sends data to the server using an HTTP request (XHR aka AJAX) specifying the target for this data (the other client).
The server stores this data in a persistent storage (local file, database, etc).
The second client periodically sends a request to the server asking if there's any new data for it to consume. This can be done using setInterval and XHR in JavaScript.
I would suggest you take a look at:
http://en.wikipedia.org/wiki/Publish/subscribe
And also, for a cutting edge way to do this, check out Socket.IO:
http://socket.io
You might want to Google on "php chat server." Building a chat server is a simple way to get started.
http://net.tutsplus.com/tutorials/javascript-ajax/how-to-create-a-simple-web-based-chat-application/
http://code.jenseng.com/jenChat/
Can anyone think of a good way to allow the server to notify the client based upon server processing? For example, consider the following events:
A user requests a deletion of data, however, due to it's long-running time, we kick it off to a queue.
The client receives a "Yes we completed your transaction successfully".
The server deletes the item and now wants to update any local structures any clients may be using (I'd also like to notify the user).
I know this can be done by client-side polling. Is there a event bus type way to do this? Any suggestions are welcome, but please keep in mind I am using GWT with App Engine.
The standard AJAX interaction is that the client sends requests to the server and expects some sort of response back fairly quickly.
In order for the server to initiate a request to the client, you will need to use WebSockets, and experimental HTML5 feature currently only supported by Chrome.
Or, to simulate this kind of interaction, you can use Comet (long-polling), made available in GWT by the rocket-gwt project.
You want server events for GWT? Have a look at GwtEventService (they couldn't have chosen a better name): http://code.google.com/p/gwteventservice/wiki/StartPage
Of course, it uses a Comet implementation, but you can't do any different when using HTTP, the client always initiates the communication. Request, response.