I have a kiosk web page that users use to sign in at an event.
On the page there is a form with a name and email input.
To prevent slow responses due to connection problems I have set up the ui to send asynchronous ajax posts.
The problem is that the connection may not be available, but I don't want to lose the data that was submitted (if the browser was accidentally closed for example). What is a way to go about saving the form data and auto retrying sending it when the connection is available?
Is this a paradigm that exists or would I have to write a full solution myself?
I was considering using HTML 5 persistent storage.
You could use evercookie or some of its ideas for storage
Related
I have a controller like the image below. This controller hides the relevant record in the database when the fetch request is sent. Do I need to use http post for such operations in this project that I wrote with Entity framework core? The problem with this controller is that the admin executes the javascript code fetch(https://localhost:5001/admin/deletepost?delete=url) on any page. As soon as this get query runs, the relevant record is hidden or deleted from the database. Is it safe as it is? How can I make it more secure? Thank you very much to everyone who replied.
Although this method is only accessible to the admin, will the deletion of the record as a result of the admin sending this request cause a deficit?
For several reasons, POST is more secure than GET.
GET parameters are passed through the URL. This means that the parameters are stored in the server log and browser history. When using GET, you can also easily change the data submitted to the server because it is in the address bar.
The problem when comparing the security between the two is that POST may block temporary users, but it cannot block malicious users. It is very easy to forge a POST request and should not be fully trusted.
The biggest security problem of GET is not the end user's maliciousness, but the third party sending a link to the end user.
Another point is that you must consider where to use GET and POST, because GET should only be used for operations that do not change database information, and only request or read information and POST data should be used when the data will be changed.
Some web scanners will automatically click on each link (usually a GET request) instead of in a button or form (usually a POSTS request) to avoid changing the database, but for example, if you perform a delete operation after the link, you The risk of clicking on the link may be easier with more automated tools.
I would like to allow a user via browser to receive updates if a database record has been changed in (near) real time without reloading the web page.
The idea is:
User opens url /dbrecord.php?id=12345
Registers for SSE (or something else) to receive updates to the record
Received on screen notification of what has been changed in the record without reloading the page
However this needs to be performant as there are a lot of DB Change events and a lot of potential users. Can you please let me know if the approach is good or are there better technologies / approaches to build something like this?
UPDATE: Found this - Server Side Events with PHP & MySQL But it requires a while(true) loop in the PHP script and this cannot be good to have the SQL Query in there?! Any feedback?
Thanks,
fj
This question isn't a code-level issue but merely a functionality question / brainstorm.
Within my PHP script I want to send a notification to another user in real time, there's 1 way I've thought of to do this, if you know any better ones be sure to leave them in the comments!
My idea for this functionality is to insert into a databse table with the user's id and the message, then on the user's end constantly loop a select request looking for notifications corresponding to their id within $_SESSION, if it's found a message then delete it from the table and display it to the user.
This seems like it could "strain" my database and I'm wondering if there's a cleaner way to do this, it would also be much appreciated if somebody could post a javascript loop with a 3 second delay and an ajax post to a php file within it,
Thanks all,
James
The cleaner way to do this would be with websockets. Polling, long polling, and streaming are going to have exactly the problem you thought you were going to have.
The message recipient needs to be listening via broadcast also through websockets. The server will notify all websockets listening for that particular event.
You don't want to block with database read and writes. Just take the action from one user and send it to all the other websockets listening for that event (the other user's client side instances)
For event history you would consider persisting to a database with a message queue.
With a properly indexed, well-structured table, it won't be a strain to the db at all. Of course, this assumes your interval is reasonable (3 seconds you mentioned is great). That's how all real-time session-checking websites work. Those that need more than that, such as chat systems, basically anything that passes data more frequently and/or in larger packets, they use websockets.
Use Websockets or Server-Sent-Events
just an idea:
User-1 send message to the Server {"message" : "hello", "target" : "User-2"}
Server checks the message and redirect it to the target User
User-2 listening for events from Websocket or Server-Sent-Events
I'm not really sure where to begin.
I'd like to be able to update a users current page when another user either updates my database or sends a specific GET/POST request (I could write it either way).
I was thinking server sent events but I made a quick test using my php server and realized a couple things. First I would need an event loop based server because using php I'd have to create a loop to keep checking my database for a specific change. Second I realized this would be very server intensive so I should look into another method.
So to explicitly ask my questions...
Is it possible to update a users current page when someone else sends a GET request to a php file on my server? How?
If I need an event loop based server what is my best option? node.js?
Is this possible with sockets if not with SSE? SSE makes more sense because I'm not looking for any user feedback.
Thanks
Websockets and something like SignalR for ASP.Net could help you. Check out the options here
You can use Ajax too.
Like this : Here
I am hoping for some help regarding an offline iPad application.
I have a form within the app that the user fills in, this form then links to a PHP script online. Obviously you can't run the script until you are on line. Is there any way at all of clicking the form submit button, if there is a connection it will connect to and run the PHP and if there is no connection it will automatically run the php in the background when a connection becomes available.
I have tried a number of different searches but have still been unsuccessful.
Thank you in advance!
It most likely is possible to solve this problem with JavaScript, but that's not so straightforward. Since you are dealing with an iOS app where it is possible to check network connection status and listen for changes, you probably should create a service that receives the form data within your app. That service should store the data locally, find out when your target server is accessible and send it.
UPDATE:
If you are dealing with a web-app, the way to go for it still to implement a service in JavaScript that uses timed events (i.e. setTimeout() or setInterval()) to check connection status. Upon submitting the form, prevent the default behaviour so the form is not submitted traditionally. Instead, store the data locally in sessionStorage or localStorage and when your service finds the target server available, read the locally stored data and send it via AJAX.