- PI Web API Channels (WebSocket connection) for multiple elements
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- The WebSocket API (WebSockets)
- WebSockets for fun and profit
PI Web API Channels (WebSocket connection) for multiple elementsThis may be a noob question, and I admit that I am a noob when it comes to websockets. With ColdFusion, channels seem to be part of the core but when I research websockets in general, excluding ColdFusion, I cannot find documentation on channels. Reason for my question, I have a third-party device that offers a websocket communication option. Reading the device documentation, it all sounds simple enough until you try to align the device with CF as the device has no mention of channels. What is the source of this mythical channel? I have several examples that you can review on my GitHub, but I believe this one might be able to help you best if the scenario above is what you are trying to accomplish. I will ask Adobe. Taking the latter first, the primary non-doc resource on CF websockets is this Adobe article which introduced them with cf The first is broadcast mode, which uses channels. The second is p2p point to point mode, which does not. The former is for a given websocket to communicate with multiple clients at once. The latter is for one-to-one communication. Second, I find many results on the web indicating that the concept of channels in websockets is not unique to CF, but supported by many other websocket solutions. As such, when you read about various resources, note they may be older and from before that extension was implemented. Or some clients may still not yet have implemented it. I will say that the last section in the Dev Guide chapter on websockets offers browser version support info. Hopefully someone with more specific experience can chime in, or with this new info you may be able to dig around to get still more clarity on the point. You must be logged in to post a comment. Show All Notifications. Join Community. Sign In. Post here. Adobe Certification. Getting Started. Admin API. Language Enhancements. Application Datasource. Application Monitoring. Application Performance. CF11 Updates.
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GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. But it seems that there is an built-in assumption that I can not open more than one simultaneous channel with the same name. The second call overwrites the first call's instance in 'channels' registry. This leads to problems down the line. I think that when I write similar code using 'SockJS' directly this works fine and I simply get two independent socket instances each openening a independent websockets connection to the server, connecting to the same websocket url. Is this a problem with WebSocketMultiplex? Is there a way to open multiple independent client side channels to the same server-side 'service'? But emulated 'websocket' still behaves like a websocket - it is one-to-one connection. That means registering channel twice make no sense - names are only used for convenience do tell one emulated ws connection from another in the protocol layer. If you want to do pub-sub which is what I see you're trying to doregister a single 'news' channel, and create your own abstraction that can distribute single event to multiple interested parties. Use EventEmitter pattern from node. My use of 'news' was misleading. I am not after a 'pub-sub' but more of a 'dialogue' between a client and service. In theory it should be possible to start multiple searches simultaneously from the same client though in practice this may be rare Eachserver-client connection has its own state. I'm not certain whether this is supposed to be possible with 'WebSockets' in general but it does work when I use plain SockJS and just instantiate multiple client side SockJS instances to connect to the same URL on the server. It seems to me that the 'name' of the service is not the right thing to use to identify a connection. Instead, the connection should be some unique id generated on the client side when a channel is created. The name should only serve to identify the service one tries to connect to, not to identify the connection itself. You are probably right. But I'm not trying to register a 'channel'. I'm trying to open a connection to service. Each connection attempt starts an independent two way conversation between the service and the client. Maybe I can figure out how to patch it to make it behave the way I want But, please note that websocket-multiplex was always intended as a sketch library that shows one of the approaches of doing multiplexing over sockjs the simplest approach. There are tons of more complex cases it doesn't cover. The code is short and understandable so that should be quite easy. Thanks for this comment, I think at some point I should revisit websocket-multiplex and make it more like websockets ie: with channel name identifying the endpoint, rather than particular connection. Duely noted. Despite your 'disclaimer' it is still the best 'socket multiplexer' thing I found so far I might fork and patch if I really need this fixed. For now, I'm probably good just creating multiple SockJs instances but that could become a problem if we need more services. This is an ancient issue, but for anyone who's finds themselves here it'd be nice to find a solution. So use a constraint in your request payload to describe the nature of your request to the service, and the same key on the response payload. Written using ES6 syntax:. Skip to content.
The WebSocket API (WebSockets)
When developers hear that WebSockets are going to land in the near future in Rails they get all giddy with excitement. WebSockets provides simple APIs to broadcast information to clients and simple APIs to ship information from the clients to the web server. A realtime channel to send information from the server to the client is very welcome. In fact it is a part of HTTP 1. However, a brand new API for shipping information to the server from web browsers introduce a new decision point for developers:. If I use the new backchannel, how do I debug it? How do I log what is going on? How do I profile it? How do I ensure it does not slow down other traffic to my site? Do I also expose this endpoint in a controller action? How do I rate limit this? How do I ensure my background WebSocket thread does not exhaust my db connection limit? If an API allows hundreds of different connections concurrent access to the database, bad stuff will happen. I do not think the majority of web applications need a new backchannel into the web server. On a technical level you would opt for such a construct if you were managing 10k interactive console sessions on the web. You can transport data more efficiently to the server, in that the web server no longer needs to parse HTTP headers, Rails does not need to do a middleware crawl and so on. But the majority of web applications out there are predominantly read applications. Lots of users benefit from live updates, but very few change information. It is incredibly rare to be in a situation where the HTTP header parsing optimisation is warranted; this work is done sub millisecond. Bypassing Rack middleware on the other hand can be significant, especially when full stack middleware crawls are a ms affair. That however is an implementation detail we can optimise and not a reason to rule out REST for client to server communications. For realtime web applications we need simple APIs to broadcast information reliably and quickly to clients. We do not need new mechanisms for shipping information to the server. WebSockets had a very tumultuous ride with a super duper unstable spec during the journey. The side effects of this joyride show in quite a few spots. At last, today, this is all stable and we have RFC which is implemented ubiquitously across all major modern browsers. However, there was some collateral damage:. Many libraries — including the most popular Ruby one — ship with multiple implementationsdespite Hixie 75 being flawed. I am confident the collateral damage will, in time, be healed. That said, even the most perfect implementation comes with significant technical drawbacks. The proxy server issue is quite widespread. Amongst the various proxy pariahs was my mobile phone network Telstra which basically let you have an open socket, but did not let any data through.
The WebSocket API is an advanced technology that makes it possible to open a two-way interactive communication session between the user's browser and a server. With this API, you can send messages to a server and receive event-driven responses without having to poll the server for a reply. Note: While a WebSocket connection is functionally somewhat similar to standard Unix-style sockets, they are not related. Get the latest and greatest from MDN delivered straight to your inbox. Sign in to enjoy the benefits of an MDN account. The compatibility table on this page is generated from structured data. Prefixed Notes. Last modified: Mar 1,by MDN contributors. Related Topics. Learn the best of web development Get the latest and greatest from MDN delivered straight to your inbox. The newsletter is offered in English only at the moment. Sign up now. Sign in with Github Sign in with Google. Chrome Full support 4. Edge Full support IE Full support Opera Full support Safari Full support 5. Chrome Android Full support Opera Android Full support Safari iOS Full support 4. Samsung Internet Android Full support 1. Chrome Full support Yes. Opera Full support Yes. WebView Android Full support Yes. Chrome Android Full support Yes. Firefox Android Full support 7. Opera Android? Safari iOS? Samsung Internet Android Full support Yes. Firefox Full support Yes. Safari Full support Yes. Firefox Android Full support Yes. Opera Android Full support Yes.