Probably this isn't the right place to ask this but I don't really know how to google it. Let me try to explain:
Let's suppose that I have 20 IP cameras from different manufacturers, each one with its own configuration page.
Also, I have a machine running a nodejs server that serves a webapp (expressjs).
Is it possible to route each one of the configuration pages through nodejs so that when I want to change some setting I access it like 'nodejsIP:port/cam/camid/' instead of 'cameraip:camport/configpage'?
In the case of that being possible, can I do the same thing with video streams from the cameras?
Yes you can.
The activity you described is called proxy. That is: You -> Proxy -> Your camera.
You can use Node.js as a proxy, there are quite a huge variety of how you could achieve this, as a an example check out the Node-http-proxy module.
Proxying the video streams might be more difficult, but once you proxy configuration pages, you shall have enough knowledge to start with the second part.
Related
I am developing my own website. So far, I've used React for the frontend and Flask for the backend. I've been doing frontend development for a while now but I'm just starting to get into the backend.
From my limited understanding, frameworks like Flask and ExpressJS create their own servers and host data that the frontend can use. It seems to me that that they automatically create websites to host and receive data. In my website, I route the backend to do what I want and use fetch requests with POST and GET from the frontend to communicate.
Although it works, to me, it seems overly complex. Why does the backend need it's own server? It seems unnecessary to create a proxy for the frontend and fetch data. Why can a website not just run custom code in the background, why does it need a service like Flask or ExpressJS to run in the background for it? These backend frameworks run Python or NodeJS in the background, but wouldn't it be much simpler if the website itself could run Python or NodeJS in the background?
I also see that in frameworks like React, you can import things and use modules— like in NodeJS. While importing some modules works, the require keyword is not allowed and normal NodeJS code will not work. Therefore, the backend will not work. Why is this— why can't you just run backend code natively? Instead you have to go through fetch and specify headers to basically translate information from your frontend to your backend.
Forgive my amateur understanding of web development, but the frontend/backend system seems overly complex to me. Thanks in advance.
Why does the backend need it's own server?
Where will the client store data so that when you open the page again the data will still be there? You can use localStorage but this is locked to that particular browser. What if someone logs in on a different device or uses a different browser?
Where will the client get the application from in the first place? Your application needs to be packaged up in a form that can be easily downloaded, and it needs an address to be loaded from. This is all considered "back end" even if you're using a static hosting service like GitHub Pages.
There's a lot of reasons why a back-end exists and needs its own server. Any application with persistent state which is expected to work across different sessions needs at least one of these.
I'm trying to set up a server and react app to both serve from one place, and host from one domain. This gives me the advantage of one repo and being able to use server side cookies instead of auth tokens.
See also this link: https://dev.to/nburgess/creating-a-react-app-with-react-router-and-an-express-backend-33l3
I also prefer to use typescript.
I really think this would be a good approach, but it is hard to find resources. All courses, free or paid, are working with separate React / Angular frontends, which then need to fetch data from a backend on a separate domain.
Does anyone know a good resource how to combine a react frontend and an express backend and host it from one place? Or are there good reasons not to do that, which I just don't see at the moment?
I'm still new to AWS and just following the documentation and asking questions here when I get stuck. Please excuse me if this question sounds really noobish.
So far, I've deployed the following:
EB to deploy my REST API
RDS to deploy my psql database
Lambda functions to handle things like authentication & sending JWTs, uploading images to S3, etc.
I have got my basic back end (no caching (just started learning about redis), etc. set up yet, just the bare bones so far) deployed.
I'm still developing my front end, and have not even thought about how I will be deploying it yet (probably another deployment on EB, since I am using universal react). I am just developing it locally but using my production env variables now so I am hitting my deployed API, etc.
One of the MAJOR things I have no idea on how to do is detecting incoming requests from client side to get the client's location by IP address. This is so that I can return the INITIAL results in your general location just like yelp, foursquare, etc. do when you go to to their sites.
For now, I am just building a web app on desktop so I just want to worry about getting the IP address to get the general area of the user. My use case is something similar to other sites you might have used which provides an INITIAL result set for things in your area (think foursquare or yelp).
Here are my questions:
What would be a good way to do this? I'm thinking of handling this in my front end react universal deployment since it will be a node server with rendered page caching. Is this a terrible idea? It would work something like
(1) request from client comes in
(2) get IP from request and lookup the IP location using some service (still not sure what I'm going to use, have found a few plus a nodejs library called node-geoip). Preferably, I can get the zip code since I am trying to save having to do so many queries by unique locations in my database, and instead return results in the zip code and the front end will show an initial map with the initial results in that zip code.
(3) return to client the rendered page with those location params if it exists, otherwise create it, send it, and cache it.
Is the above a really dumb idea? Maybe you have already done something like this, and could share your wisdom :)
Is there an AWS service which can already handle something like this for me? Perhaps there's some functionality which can already do this.
Thanks.
AGAIN - I apologize if this is long winded. I don't know anyone in real life who can help me and I feel alone :(. I appreciate the help you guys can provide.
There are two parts to this:
Getting the user's IP address. You mentioned you're using 'EB' - I presume you mean AWS ELB (Elastic Load Balancer)? If so, then you need to read the X-Forwarded-For HTTP header in your app code, since otherwise what you'll really detect is the ELB's IP address. X-Forwarded-For contains the user's real IP - or rather, the IP of the end-connection being made (there's no telling if this is really a VPN, Proxy or something else-- but it's as far as you can get with an IP.)
Querying an IP DB that can turn the addr into a location object. There are tons of libraries for you. Assuming you're using Node, you can use node-geoip as you mentioned. Or you can just search 'geoip service' on Google and find managed services, like Telize on Mashape. If you don't want to manage the DB lookup yourself or keep the thing up to date, then a managed service would help.
In either case, it's likely that you'll be doing asynchronous look-ups. In that case, you might want to use async/await to get the user's full object before injecting that into your React props and ultimately rendering it as a HTML string that's sent down to the client.
You could also use a library like redial to decorate your components with data requirements, and return a Promise you can await on to know when you're okay to render.
Since you probably want to enable client routing too (i.e. where the user can click on a route in their browser, and the server isn't touched at all), then you will probably need some way to retrieve the IP address/results based on that IP even when the server isn't involved in the initial render.
For that, you could write a REST service that retrieves the results. Or write a GraphQL back-end that gets the data. It doesn't matter how you write it, since the server will have access to the X-Forwarded-For header and can use that to retrieve the results and send back location-aware data.
FYI, I'm writing a React starter kit (called ReactNow) that uses rxjs for handling async streams. It's not ready yet, but it might help you figure out the code layout that would offer a balanced mix between rendering on the server, and writing universal code that requires some heavy lifting from the server.
I am admittedly a complete noob in all things server, Linux, and websockets. I finally managed to set up a VM running Apache, Tomcat, and Railo that I could connect to and serve up CFM pages, all the while learning UNIX command line navigation, server theory, etc, etc...
Here's my problem -- there is only one Railo websocket extension and it is super rinky-dink (I had to modify the CFC just to get the service to start) but I can't get a websocket connection up (I keep getting "unexpected code 200" in Google Chrome). There is minimal documentation, which is not helpful at all.
Basically, I am trying to do some prototyping for a future project that will use websockets. I like Railo for its speed, security, and excellent ability for very database heavy operations. I am interested in Node, but don't know how to get the same security and DB functionality out of Javascript as I can with CFML.
So I have a couple questions: what are my best options for WebSocket servers? Should I be trying to use Apache and/or Tomcat? People keep saying it's totally not worthwhile to have something like Node.js running the websockets portion and something else doing the heavy lifting behind it -- why is this? I'm more than happy writing WS handlers in whatever language if I can just get a nudge in the right direction, some excellent tutorials (I can't seem to find much in this department), or good feedback on how to, from the ground up, set up my Linux box to handle websockets -- and preferably how to handle both websockets and a robust language like Railo.
The Railo extension works fine for me.
What about submitting some test code so that we can debug it? Of course the websockets projects is very young and in full deployment. So feel free to fork and submit patches or suggestions.
You have plenty of options:
Railo Google Group
https://groups.google.com/forum/?fromgroups#!forum/railo
Github Extension Repository
submit a but in the Railo Jira bugtracker
The main problem of node.js is that it's mono-thread : you won't be able to do background tasks using it and local IO will block your server.
A solution I use is Go. It's very fast, has very good concurrency features and has integrated websocket and json libraries (sample : http://gary.beagledreams.com/page/go-websocket-chat.html). An efficient web application server is made in a few dozens lines of Go. You'll find that there is still much less documentation on internet than for java or even node.js through.
There are a few implementations of websockets in java but as I'm in the process of switching everything I had in java to Go I hadn't tested them. I know I use Google gson for the json encoding in java and it's very good.
The "unexpected code 200" is caused by Railo's web socket server sending an outdated response. They changed the web socket spec and Chrome uses the newer spec.
The problem seems to be caused by chrome & co implementing the new spec, "draft-ietf-hybi-thewebsocketprotocol-17". It requires the server to respond with "HTTP/1.1 101 Switching Protocols" rather than 200 OK.
The solution here would be to either update the Railo web socket extension yourself or use some other solution:
Here is a complete demo of a web socket chat server written in PHP.
http://www.flynsarmy.com/2012/02/php-websocket-chat-application-2-0/
I have used this myself to implement a real-time HTML chat served from an Arch Linux machine that I had lying around. Configuration consisted of simply setting up Apache and PHP then changing the IP address in index.html and in server.php to the external ip address of the server machine.
This flynsarmy demo includes a recent version of PHPWebSocket which is an open source web socket server written entirely in PHP and contained in a single file. The demo hooks into three callbacks: connect, message recieved, and disconnect.
The important thing to note, for me, was that the web socket protocol supports text only, not binary so while extending it for my own chat app I had to implement my own commands to help control the server. Commands in my case looked like this:
!kickusers: username, another_username, a_third_username
My server code would check the first character of all messages for a '!' and if present would treat it as a command. Then I slice up the string to get the command "kickusers" and a list of users to kick. Then I call the appropriate kick function and pass it the array of usernames.
Since my scenario was a chat client this meant that the user could literally type this command into chat and the server would accept and respond to it.
The way all this is deployed on my server is like so:
I have Apache serve the index.html page when the user goes to that location on my server in their browser. The only purpose Apache plays here is to give index.html to the client who requested it.
The index.html page contains html to display the chat and javascript to send and recieve chat to/from the server. Basically, index.html is simply a chat client written in HTML and Javascript and it runs in the browser.
I run server.php via ssh on the server to start up the WEB SOCKET server (totally separate from Apache) which just sits there and handles chat stuff like echoing text to the other connected clients etc.
Though the Arch wiki on installing Apache and PHP is specific to Arch in the way that you install the Apache and PHP packages the sections on configuring Apache and PHP apply to all. I'll save you the google query and give you the link here if you like: https://wiki.archlinux.org/index.php/LAMP
As for prototyping, the reason I gave the link to Flynsarmy's chat demo is because his comments are helpful, he wrote a blog about it, and it comes as a very simple yet complete example of how to do something with web sockets in php.
I'm thinking about exploring the idea of having our client software run as a service on a high port and listen for simple http GET requests from 127.0.0.1. The theory is that I would be able to access this service via js from a web page that is served from my site.
1) User installs client software that installs itself as a service and waits for authenticated requests on 127.0.0.1:8080
2) When the user hits my home page js on the page makes an xhtml request to 127.0.0.1:8080 and asks for the status
3) The home page then makes another js request back to my web server sending the status that it received.
This would allow my users to upload/download and edit files on a USB attached device in real-time from a browser. Polling could be the fallback method which is close to what we do today.
Has anyone done this and what potential pitfalls are there? Will this even work?
I can't see any potential pitfalls. I do have a couple of points however.
1/ You probably want to make sure your service only accepts incoming connection from the local machine (127.0.0.1). Otherwise, anyone could look at your JavaScript and figure out that it's talking to [your-ip]:8080. They could then try that themselves from a remote site (security hole).
2/ I wouldn't use port 8080 as it's commonly used for other things (alternate HTTP servers, etc.). Make it configurable and choose a nice high random-type value.
3/ I'm not sure what you're trying to do with point 3 but I think you're trying to send the status back to the user. In which case, why wouldn't the JavaScript on your home page just get the status in a single session and output/update the HTML to be presented to the user? Your "another js request back to my web server" doesn't make sense to me.
You may not be able to do a xml http request to 127.0.0.1 as XMLHTTPRequest is usually limited to the same domain as the main content is being served from. I'm not sure if this restriction applies if the server is on the client's machine. That being said, you could still create a <script> tag that had the src pointing to 127.0.0.1, and have the web server return some Javascript to run. If you only need a simple response, this could work well.
I think it is much better for you to avoid implementation of application logic in JavaScript and html. Once user clicks button on a web page JavaScript should send request to your service and allow it do the rest of the work.
You could have problems with step 1 (Client installs itself) depending on your target user base.
You will need a customised install for each supported environment (Win2K, Vista, Linux, MAC OS 9.0/10.0 etc.).
If your user is on a locked down at work PC this simply wont be allowed.
To some users this might look distressingly similar to a trojan unless you explicitly point out you will be installing software that runs as a service.
You didnt mention an unistall procedure. Users resent "Adobe" like software which installs itself and provides no sensible un-install options
Ohterwise the approach is sound, and, there are are couple of commercial products out there that use exactly this approach!