I would like to develop a webpage (using any technology) with these conditions:
When client A types the web address on his browser, they automatically receive a remote IP (no other data)
With this IP, Client A automatically request some data from that IP (Client B)
Client B sends the requested information to Client A.
Which technology and libraries could I use to develop this webpage? (Javascript, Applets, browser plugin...) I think is some kind of P2P, so it should be possible to develop it.
Let's put one example.
Imagine that the webpage I have to program is www.hi.com/test.html.
I type it on my browser and receive automatically this IP: 212.22.62.106
My browser automatically request data to 212.22.62.106, which is another client of www.hi.com/test.html
This second client sends me the requested information, which is the only one is shown on my browser.
THANKS
Just about everything in browser security is going to fight this model - Ajax, javascript in general, applets, cookies - they're all tied to the current domain.
To do this, you're going to need to get something onto the desktop, if only in the form of an ActiveX control, which will severely limit your browser-base.
I think you're barking up the wrong tree - maybe if you could pop up one level of abstraction and tell us what you're trying to accomplish with this model?
This is not possible with web page, you're looking in the wrong direction.
You'll have to build your own application which by the way sounds really similar to eMule.. :)
Related
I'm new to HTML and coding period. I've created a basic HTML page. In that page i want to create dropdown selections that produce outputs from my SQL database. MSSQL not MySQL.
EX: If I select a table or a column from dropdown one and then input a keyword for selection box 2. I want it to produce a table that shows the information in that table/column with that keyword.
If I select a medical name from dropdown and I want it to show only medical names that are equal to Diabetes. and then show me those rows from my database to a table. How would I show that in HTMl from connecting to the database, to creating the dropdown selection linked to the database, and then being able to select the criteria for what I want to be displayed. and then showing that in a table or list format.
Thank you in advance
OK, Facu Carbonel's answer is a bit... chaotic, so since this question (suprisingly) isn't closed yet, I'll write one myself and try to do better.
First of all - this is a VERY BROAD topic which I cannot answer directly. I could give a pile of code, but walking through it all would take pages of text and in the end you'd just have a solution for this one particular problem and could start from scratch with the next one.
So instead I'll take the same path that Factu Carbonel took and try to show some directions. I'll put keywords in bold that you can look up and research. They're all pieces of the puzzle. You don't need to understand each of them completely and thoroughly from the beginning, but be aware what they are and what they do, so that you can google finer details when you need them.
First of all, you need to understand the roles of the "server side" and "client side".
The client side is the browser (Chrome, Firefox, Internet Explorer, what have you). When you type an address in the address bar (or click a link or whatever), what the browser does is it parses the whole thing and extracts the domain name. For example, the link to this question is https://stackoverflow.com/questions/59903087/sql-drop-down-selections-in-html?noredirect=1#comment105933697_59903087 and the domain part of that is stackoverflow.com. The rest of this long jibberish (it's called an "URL" by the way) is also relevant, but later.
With the domain in hand the browser then uses the DNS system to convert that pretty name into an IP address. Then it connects via network to the computer (aka "server") designated by that IP address and issues a HTTP request (HTTP, not HTML - don't mix these up, they're not the same thing).
HTTP, by the way, is the protocol that is used on the web to communicate between the server and the browser. It's like a language that they both understand, so that the browser can tell the server hey, give me the page /questions/59903087/sql-drop-down-selections-in-html. And the server then returns the HTML for that page.
This, by the way, is another important point to understand about HTTP. First the browser makes its request, and the server listens. Then the server returns its response, and the browser listens. And then the connection is closed. There's no chit-chat back and forth. The browser can do another request immediately after that, but it will be a new request.
Now, the browser is actually pretty limited in what it can do. Through these HTTP requests it gets from the server the HTML code, the CSS code and the Javascript code. It also can get pictures, videos and sound files. And then it can display them according to the HTML and CSS. And Javascript code runs inside the browser and can manipulate the HTML and CSS as needed, to respond to the user's actions. But that's all.
It might seem that the Javascript code that runs inside the browser is all powerful, but that is only an illusion as well. It's actually quite limited, and on purpose. In order to prevent bad webpages from doing bad things, the Javascript in each page is essentially limited to that page only.
Note a few things that it CANNOT do:
It cannot connect to something that doesn't use HTTP. Like an SQL server.
It can make HTTP requests, but only to the same domain as the page (you can get around this via CORS, but that's advanced stuff you don't need to worry about)
It cannot access your hard drive (well, it can if the user explicitly selects a file, but that's it)
It cannot affect other open browser tabs
It cannot access anything in your computer outside the browser
This, by the way, is called "sandboxing" - like, the Javascript code in the browser is only allowed to play in its sandbox, which is the page in which it was loaded.
OK, so here we can see, that accessing your SQL server directly from HTML/CSS/Javascript is impossible.
Fortunately, we still need to talk about the other side of the equation - the web server which responded to the browser's requests and gave it the HTML to display.
It used to be, far back in the early days of the internet, that web servers only returned static files. Those days are long gone. Now we can make the webserver return -- whatever we want. We can write a program that inspects the incoming request from the browser, and then generates the HTML on the fly. Or Javascript. Or CSS. Or images. Or whatever. The good thing about the server side is - we have FULL CONTROL over it. There are no sandboxes, no limits, your program can do anything.
Of course, it can't affect anything directly in the browser - it can only respond to the browsers requests. So to make a useful application, you actually need to coordinate both sides. There's one program running in the browser and one program running on the web server. They talk through HTTP requests and together they accomplish what they need to do. The browser program makes sure to give the user a nice UI, and the server program talks to all the databases and whatnot.
Now, while in browser you're basically limited to just Javascript and the features the browser offers you, on the server side you can choose what web server software and what programming language you use. You can use the same Javascript, or you can go for something like PHP, Java (not the same as Javasctipt!), C#, Ruby, Python, and thousands of others. Each language is different and does things its own way, but at the end of the day what it will do is that it will receive the incoming requests from the browser and generate some sort of output that the browser expects.
So, I hope that this at least gives you some starting point and outlines where to go from here.
First of all there is something that you need to know to do this, and that is the difference between a front-end and a back-end.
Html is a front-end technology, they are called like that because that's what is shown to the user and the back-end it's all mechanisms that run behind the hood.
The thing is, in your front-end you can't do things of back-end, like do querys from a database, manage sessions and that kind of thing.
For that you need a back-end running behind, like php, ruby, node.js or some technology like that.
From the html you can only call functions on the server using things like <form action="/log" method="POST"> this wold call the action /log that you should have already program on your back-end. Don't get confuse with this, there is plenty of ways to sending request to your back-end and this is just one way to do it.
For your specific case I recommend you to look up for ajax, to do the query on your database with no need of the browser to refresh after the query is made.
Some topics you need to know to understand this is:
-what's front-end and back-end and their differences.
-what is client-server architecture
-ajax
-http requests
-how to work with a back-end, doing querys to the database, making routes, etc.
-and for last, wile your server it's not open to the world with your own domain name, what is localhost and how to use it.
I hope that this clarify a bit this, that is no easy thing, but with a bit of research and practice you will accomplish!
I'd like to login to a RESTful back-end server written in Laravel5, with the single page front-end application leveraging Polymer's custom element.
In this system, the persistence(CRUD) layer lives in the server. So, authentication should be done at the server in responding to client's api request. When a request is valid, the server returns User object in JSON format including user's role for access control in client.
Here, my questions is how I can keep the session, even when a user refreshes the front-end page? Thanks.
This is an issue beyond Polymer, or even just single page apps. The question is how you keep session information in a browser. With SPAs it is a bit easier, since you can keep authentication tokens in memory, but traditional Web apps have had this issue since the beginning.
You have two things you need to do:
Tokens: You need a user token that indicates that this user is authenticated. You want it to be something that cannot be guessed, else someone can spoof it. So the token better not be "jimsmith" but something more reliable. You have two choices. Either you can have a randomly generated token which the server stores, so that when presented on future requests, it can validate the token. This is how just most session managers work in app servers like nodejs sessions or Jetty session or etc. The alternative is to do something cryptographic so that the server only needs to validate mathematically, not check in a store to see if the token is valid. I did that for node in http://github.com/deitch/cansecurity but there are various options for it.
Storage: You need some way to store the tokens client-side that does not depend on JS memory, since you expect to reload the page.
There are several ways to do client-side storage. The most common by far is cookies. Since the browser stores them without your trying too hard, and presents them whenever you access the domain that the cookie is registered for, it is pretty easy to do. Many client-side and server-side auth libraries are built around them.
An alternative is html5 local storage. Depending on your target browsers and support, you can consider using it.
There also are ways you can play with URL parameters, but then you run the risk of losing it when someone switches pages. It can work, but I tend to avoid that.
I have not seen any components that handle cookies directly, but it shouldn't be too hard to build one.
Here is the gist for cookie management code I use for a recent app. Feel free to wrap it to build a Web component for cookie management.. as long as you share alike!
https://gist.github.com/deitch/dea1a3a752d54dc0d00a
UPDATE:
component.kitchen has a storage component here http://component.kitchen/components/TylerGarlick/core-resource-storage
Simplest way if you use PHP is to keep the user in a PHP session (like a normal non SPA application).
PHP will store the user info on the server, and generate automatically a cookie that the browser will send with any request. With a single server with no load balancing, the session data is local and very fast.
I'm attempting to make a mail client that is HTML5/JS only where users would have to define their mail server and credentials.
I've surfed google leading to dead ends and figured that this is the next best place (or superuser.com).
I was thinking of using HTML5 WebSocket if I could to make the connection to the server but I don't know enough of smtp, imap, or pop3's architecture to understand how javascript could pass the args and perform what I want it to do.
PHP cannot be involved in this project otherwise I wouldn't be asking the question.
Any help in locating this would be fantastic.
Nothing is impossible. Except this.
In standard HTML or JavaScript, you can't make raw-socket connections, which is what you'd need to speak any of the protocols you've listed. The WebSocket API doesn't help you, because the server must also speak WebSockets, and mail servers don't. This is actually all a good thing, though. Imagine if you visited a random website and it telnetted to your home router, setting it on fire and burning down your house. That's what websites would be able to do if they could initiate plain TCP socket connections.
You have a few options I can think of, neither of which involves building a webpage. (And to be clear, you didn't say your project had to be a webpage; you merely said HTML/JS, so these are indeed legitimate options.)
First is something like node-webkit. As the readme says, "You can write native apps in HTML and Javascript with node-webkit." You'll still have to distribute it as a native app, because that's what it is.
Second is a Chrome app, specifically using the chrome.socket API. But have fun writing a TLS layer over those sockets, which you'll find is a requirement for almost any mail server these days. If you succeed in doing that, you'll be able to distribute your mail client in the Chrome Web Store, where I assure you an email client will be quite popular.
Third, write a webserver that operates locally, so your users will visit something like http://localhost:9999/mail in their browser. This will be a real pain to distribute, but you can use almost any technology you want.
I'm sure there's a fourth valid option, and someone else can chime in on that one.
Best of luck.
What I would like to do is create a canvas that will show a network map. It's not really a network map but in terms of explaining it the network map example works best to not bog you down with details that don't pertain to my question.
On the network map I want to display routes the traffic takes. These routes change in time, sometimes as frequently as multiple times per minute. On the server side I have a log file to which each route change is appended as it happens.
I know how to create the canvas, I know how to draw my routes onto the canvas.
Is it possible to have the server push an update to the canvas without requiring a page reload/refresh, essentially requiring no user interaction at all? The routes drawn just automagically change?
This would need to work on IIS so a jscript or .Net based solution would be necessary. I won't be able to install PHP, Python, Ruby etc.
Thanks in advance for any insights you can provide.
I recommend that you look at a WebSockets solution to push the information from the server to the client (JavaScript). When you receive the update you can update the canvas as required.
Technologies you should look at if your preferred server technology is .NET would be a service like Pusher, who I work for, and our .NET APIs which let you push updates to the client via our REST API.
If you would prefer to host your own realtime infrastructure then you could look at WebSync (which is actually a Comet technology) which integrates with IIS and also XSockets. There are also a number of realtime technologies on this guide which may interest you. If you've any further questions just let me know.
Server-Sent Events: http://www.html5rocks.com/en/tutorials/eventsource/basics
( Server-sent events is a technology for providing push notifications from a server to a browser client in the form of DOM events. The Server-Sent Events EventSource API is now being standardized as part of HTML5[1] by the W3C. )
Yes, I've done this before (with an ajax-based drawing application). It's very possible. Send packets of information via AJAX (JSON or something), interpret them, and draw them on the client's canvas element. This is trivial to design (and easy to implement using something like jQuery). It seems that you already figured out you need to have a server-side script that pushes information to a web page and a web page that actually draws stuff on the canvas. That's essentially all it is.
I've been playing with HTML5 location lookups recently and its relatively straightforward to pull someones location from a device like an iPhone.
I want to write an app that uses location data, but its important that the location be factual. In other words I need to prevent people from authoring a fake post to the backing website / web service with mocked up GPS coordinates.
Is there anyway to collect GPS coordinates from a mobile device using the HTML5 geolocation apis and securely transmit that back to a web service in a way that someone wouldn't be able to author a post with the same data and "game the system" so to speak?
Not without some serious encryption on the payload on the client. Which if there is money involved, someone will reverse engineer and figure out how to create valid payloads themselves. Remember if there is money or fame involved then somebody will think the effort to do something like this is "worth it". If your web service is public and not using some kind of encryption nothing on the client will ensure that someone with a network connection can't sniff your protocol and fake whatever data they want. And SSL won't cut it. Anyone can proxy the SSL connection on their local network decrypt the payload and inspect it to their hearts content.
No. Completely agree with the answer from fuzzy lollipop. If you’re talking to a remote machine, the data can always be faked. Always always. What makes you certain you’re even talking to a mobile device at all? The User-Agent string? Pfft, it can be faked. Talking to a GPS? Pfft, could be coming from a predefined path. Talking to a web browser? Pfft, could be a bot, or some other malware.
And don’t think encryption (i.e. HTTPS) is going to help you. The client could edit any of your HTML, CSS, or JavaScript on-the-fly — take Firebug or Greasemonkey for example.
The reasons why you can’t trust the client are the same as the reasons why exploits such as SQL or HTML injection are so common. Ever heard the phrase “the customer is always right”? Well, the customer may be right, but the client is always untrustworthy.
The system is there to be gamed. As flaws are discovered, you patch them one by one. It’s more like leapfrog, rather than achieving the holy grail. Bruce Schneier’s quip “security is a process, not a product” comes to mind. Asking for a system that “can’t be gamed” is missing the point. What you need to be doing is creating a system where the server sanitises the data, and/or rejects bad data — fuzz testing is not a bad idea, either.
That’s about the best you can do without shipping custom untamperable mobiles to your customers with the OS in ROM, and the inside sealed with epoxy.