I am trying to Ajax load from LAN's mysql using chrome app.
I am proposing Ajax because I need chrome app to load up any update in the SQL instantaneously.
Since this app is only used in LAN network, I presume there is no need to maintain a web server (aka running Apache). Can anyone provide some hints as this answer I found on the forum does not help me (an absolute newbie) too much.
https://developer.chrome.com/extensions/xhr
Thank you.
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Since this app is only used in LAN network, I presume there is no need to maintain a web server (aka running Apache).
AJAX refers to making a HTTP request to.. something.
Something that can answer HTTP requests is called a web server.
So, you do need some sort of web server. It may be a component of MySQL server, but it's still a web server.
That said, it doesn't look like MySQL has a supported HTTP interface. There is an experimental HTTP Plugin that provides REST API, but it's experimental. Therefore, you would need a separate server application that does what you need.
That said,
I am proposing Ajax because I need chrome app to load up any update in the SQL instantaneously.
AJAX is not a magic bullet. It works well for requesting data, but it is not adapted to receiving updates initiated by the server you're talking to. It's a request-response cycle, and while there are some techniques to use it to push data they are hacks.
WebSockets evolved to cover the bidirectional, persistent communication needs. However, this again would require a web server to sit as a proxy between your DB and your app - this time, WebSockets-capable.
That said, building a Chrome App allows you to connect to a database directly - since Chrome Apps are capable of using chrome.sockets API. You would need a JavaScript library specifically adapted to the task, but those probably exist.
That said, and noting that I'm not an expert on databases, but..
Databases are not designed to notify you about updates. You need to poll them to see if the data has changed. You will not get it instantaneously no matter what interface you use. You'll need to periodically monitor it for changes.
Considering this, depending on what you're trying to ultimately do you may be choosing a wrong instrument.
There's a lot of "buts" here, and it seems like a complex task. You should re-evaluate your readiness as an "absolute newbie" to undertake it.
Related
This article describes how a websocket server for a chat application can look. We are planning to implement something similar; when a message is sent to the server it is sent to the correct recipient based on an authentication token and the message gets saved in a mysql database.
We will eventually host the server on Google App Engine, and I suspect that that will cause some issues with the above described approach, since that depends on all clients being connected to the same server, and that probably won't be the case since multiple instances will be created as needed. Is there a way to connect all instances so that this won't be a problem (Pub/Sub maybe? (That will cause additional costs though)), or should we find a different solution?
One idea I had was to use mysql-events to monitor the binlog from the websocket server for the creation of new rows in the messages table, but I read somewhere that that wasn't recommend. But I can't find where I read that, and maybe that is the best solution.
Since you asked about other solutions, I would recommend looking at Firebase and specifically the Realtime Database. Out of the box it provides all of the functionality that you need for realtime communication between connected clients and Cloud Messaging for clients who aren't.
Here's a tutorial that uses Firestore to create a realtime chat web app, but it can all be applied to the Realtime Database with minor modification. I say that because Firestore has expensive writes, which in my opinion make it unsuitable for a chat backend.
So I have an application that uses webRTC to set up a video chat between 2 browsers. I'm using node.js for the application and socket.io to make the handshake. I have made a successful test in the chrome browser in connecting the clients so now the next step is to allow this to be used by more people.
I was wondering what would be the best way to approach the server side of creating 'rooms' and connecting two people who would like to chat. In the test I just put the one who created the offer in an object and if the second person matched the first (by UUID or a keyword) then the connection would be made but what would be a better, more secure, and more fitting method to do this with more people?
My application currently has MySQL so should I make use of a table? I feel like that would be time consuming/too much calling to a db... Should I focus more on Socket.io? Can node's socket.io handle a lot of connections to the server well enough?
If my question isn't clear please tell me.
P.S. any GOOD tutorials or articles on setting up a webRTC connection on mozilla would be great. I can add the connection but for some reason adding the stream of the one who 'creates offer' isn't being sent over.
A "room" in WebRTC will just be use for signaling, a way of sending messages before the actual connection is initiated.
"My application currently has MySQL so should I make use of a table?" - that's not exactly the best approach. If your application uses a framework/technology/etc, it doesn't mean that you should use it everywhere. You should use a technology when it answers best your needs. If such a room has to have some persistent attributes, then it makes sense to make use of a persistent storage, such as a database.
I am working on a project that uses Couchbase Server and Sync Gateway to synchronize the contents of a bucket with iOS and Android clients running Couchbase Lite. I also need read and write access to the Couchbase Server from a Node.js server application. From the research I've done, using shadowing is frowned upon (https://github.com/couchbase/sync_gateway/wiki/Bucket-Shadowing), which led me to look into the Sync Gateway API as a means to update the bucket from the Node.js application. Updating existing documents through the Sync Gateway API appears to require the most recent revision ID of the document to be passed in, requiring a separate read before the modification (http://mobile-couchbase.narkive.com/HT2kvBP0/cblite-sync-gateway-couchbase-server), which seems potentially inefficient. What is the best way to solve this problem?
Updating a document (which is really creating a new revision) requires the revision ID. Otherwise Couchbase can't associate the update with a parent. This breaks the whole approach to conflict resolution. (Couchbase uses a method known as multiversion concurrency control.)
The expectation is that you're updating the existing contents of a document. This implies you've read the document already, including the revision ID.
If for some reason you don't need to the old contents to update the document, you still need the revision ID. If you work around it (for example, by purging a document through Sync Gateway and then pushing your new version) you can end up with two versions of document in the system with no connection, which will cause a special kind of conflict.
So the short answer is no, there's no way to avoid this (without causing yourself other headaches).
I am not sure why your question was downvoted, as it seems like a reasonable question. You are correct, the Couchbase bucket that is used by Sync Gateway should probably best be thought of as "opaque", you should not be poking around in there and changing things. There are a number of implementations of Couchbase Lite, such as one for Java, .NET, and Mac OS X. Have you considered making a web service that, on one side, is serving your application, and on the other side is itself a Couchbase Lite client? You should be able to separate your data as necessary using channels.
I have an application hosted in openshift. Now I want figure out how many request can handle in order to check the speed and availability.
So my first attempt will be generate a multiple HTTP GET requests to my Rest Service(made in python and hosted in openshift).
My fear is can get my IP workplace banned regarding this looks like an attack.
In the other hand I see there are tools like New Relic or DataDog to check metrics, but I don't know if I can simulate http requests and then check the response times.
Openshift Response
I finally wrote to Openshift support and they told me I can simulate http requests without worries.
I recall the default behavior being that each gear can handle 16 concurrent connections, then auto-scaling would kick in and you would get a new gear. Therefore I would think it makes sense to start by testing that a gear works well with 16 users at once. If not, then you can change the scaling policy to what works best for you application.
BlazeMeter is a tool that could probably help with creating the connections. They mention 100,000 concurrent users on that main page so I don't think you have to worry about getting banned for this sort of test.
I've been doing some research of the best way to show an "users online" counter which is updated to the second trying to avoid continuos ajax polling.
Obviously WebSockets seems to be the best option. Since this is an intranet I will make it a requirement to use Chrome or Safari so there shouldn't be compatibility issues.
I've been reading some articles about WebSockets since I'm new to it and I think I pretty much understand how it works.
What I'm not so sure is how to implement it with PHP. Node.js seems the natural choice for this because of it's "always running" nature but that's not an option.
Why I'm most confused about is the fact that PHP runs and when it's done, it ends. If PHP ended, wouldn't the socket connection be lost? Or if the php re-runs it will look back the user by ip? (I don't see that likely)
Then I found this library
http://code.google.com/p/phpwebsocket/
but it seems to be a little old (it mentions only Chrome nightly is compatible with WebSockets)
In one point says "From the command line, run the server.php program to listen for socket connections." which means I need SSH, something many shared hosting plans don't have.
And my other doubt is this other line in the source of that library:
set_time_limit(0);
does that mean that the php file will run continuously? Is that allow in shared hosting? From what I know all hostings kill php after a timeout of 1 o2 minutes.
I have a mysql table with online users and I want to use PHP to broadcast via websocket the amount of logged in users to those online users. Can someone please help me or point me somewhere with better information how this could be achieved?
Thanks
Websockets would require lots of thing even on dedicated hosting, put aside shared hosting.
For your requirement server sent events (sse) is the correct choice, since only the server will be pushing data to the client.
SSE can simply call a server script, very much like ajax, but the client side will receive and be able to process data part by part as it comes in. Dom events would be generated whenever some data comes in.
But IE does not support SSE even in version 10. So for IE you have to use some fallback technique like "foreever iframe".
as far as hosting is concerned, ordinary shared hostings (and those which are not very cheap) would allow php scripts to run for long, as long as they are not seen as a problem.