I am trying to make an html app for local use, consisting of an HTML page using Google Maps API V3, a SQLite database, and a SimpleHTTPServer script.
The workflow is the following:
User starts the server and opens the page, which contains a map with a set of markers, and a form with filters similar to those of Google Fusion Tables;
User interacts with form, which sets some parameters for a query;
When the user clicks "Submit", page sends a request to HTTPServer, whose request handler queries the SQLite database and returns the result as JSON/JSONP/something-else;
Some function takes back the data and map is updated;
My doubts are more conceptual than anything else, and specifically I would like to know (how/where to look for):
How should I send a request for the server in javascript, and how to listen back to it?
How should the server send data to the request, in order to update its value instead of refreshing the page?
Sorry if my questions seem obvious, but HTTP is something very new to me, and so is client-server communication.
Thanks for reading!
I think you can use CGIHTTPServer.
ref:
http://pydoc.org/2.5.1/CGIHTTPServer.html
Q:How should I send a request for the server in javascript, and how to listen back to it
A:Please google "ajax". "jquery" is one of the most convenient javascript library for ajax.
Q:How should the server send data to the request
A:just use "print" in python script which is called by CGIHTTPServer.
In this case, the output of "print" will be the response to http client(web browser).
In the script mentioned above, you should extract request parameter sent by http client,
with "do_Get()" or do_Post() function.
Related
I'm in a situation where I'm not sure what is the correct way of doing this. I'm trying to take a large json file, send it to the server, process and reorder it, and then send it back to the client. I don't want to store any data in a database. I know there's the HTTP GET verb, but the amount of data I would be inputting would be longer than the max length URI. I also read that you shouldn't try to do this with a HTTP POST either.
I looked into WebSockets as well but to me it appears to be overkill. I would only need the socket for the time that it takes to do the computations, then I would close it. Also I want to share the data with only the client who sent it to me.
Does any one have recommendations as for what to do. Maybe just a push in the right direction with a few links I can read. I'm really looking for something that runs down the middle of these two methods.
Why don't you just use a HTTP POST request? Taken from an info box on
https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST
> Request has body Yes
> Successful response has body Yes
> Safe No
> Idempotent No
> Cacheable Only if freshness information is included
> Allowed in HTML forms Yes
As you see, a HTTP POST request is used for sending data to the server, and if the POST request was successful, the server sends data back to the client. Perfect for your situation, I think.
A POST request doesn't have to be used within a HTML form; you could use XHR, AJAX, the fetch API, or any other way you can find to send the server a POST request. And yes, you could send JSON data with it.
If you need more convincing:
When the POST request is sent via a method other than an HTML form — like via an XMLHttpRequest — the body can take any type. As described in the HTTP 1.1 specification, POST is designed to allow a uniform method to cover the following functions:
Annotation of existing resources
Posting a message to a bulletin board, newsgroup, mailing list, or similar group of articles;
Adding a new user through a signup modal;
Providing a block of data, such as the result of submitting a form, to a data-handling process;
Extending a database through an append operation.
Notice that there, it said that a POST request can be used to provide a block of data to a data-handling process.
Hope this helps you. :)
I'm doing a project which I want to send sensor's data to Firebase database. This connection must be via GPRS. To set or to push any data to Firebase database, it should be done using javascript and HTML, but the Arduino can't use javascript directly. Is there any way to make the connection?
I have a website. Would it be helpful to do the connection?
I will be really thankful if someone gave me a simple steps to follow.
Thank you in advance.
You could request web site links ( http request) from the arduino.And in this request you can pass details to the database.This is how the data is stored to the database from Arduino.
I am bit back about firebase database.
But let me tell what we did for storing data to a normal database.We made a PHP script such that if its link is requested with data ,it would store the data to the database.Then we made Arduino code in such a way as to request that link each time with the corresponding value to be stored.So if you can do PHP scripting for firebase data entry then its easier ( just request that link from Arduino).I think PHP insertion to firebase database is available.
You can also pass data to a website too using the above method ( simple modification in url would do that ,pass data to be stored).But the problem is how you would store it to the database from that webpage.If you have a way for that you can try it too.
I have a PHP page named update_details.php?id=xyz which has a query for getting the details and updating the login time of the users.
The users have a profile page named profile.php?id=xyz. So for different users the profile page is different like profile.php?id=abc, profile.php?id=def etc. Now this profile.php has an ajax function that sends the user id to the update_details.php through ajax call so that the update_details.php can update the record.
Now for example if I have 2000 users and all of them open their profile page simultaneously. Now my question is will the update_details page be able to handle this. I mean is it one update_details.php or each update_details.php?id=abc, update_details.php?id=def etc is considered to be a seperate one.
To be more precise, when 2000 users are updating their record through 2000 ajax calls, are the calls going to one update_details.php or to the one according to their ids like update_details.php?id=abc, update_details.php?id=def etc. TIA
Okay, let's check how the request goes from the browser till it's served and the browser gets a response.
The client clicks on a link, maybe a button.
The browser makes a HTTP request and sends it to the server ( that maybe Apache, nginx, whatever you use )
The server analyzes the request, checks its rules.. Saying : I found a rule when I hit a url with .php extension, I run a php interpreter and pass it the request info..
The server spawns new process or assign the request to one of its workers ( depends on the internals of the server ).
How many concurrent php processes will run ? it depends on the web server configuration and design.
So to answer your question, each php process is running has its isolated memory segment even if they are executing the same instructions from update_details.php
Think of it like 10 workers in a factory crafting a chair following the same instruction, but each one uses a different paint color, wood type, etc..
I am trying to write my first chrome extension. The workflow goes something like this -When the extension is installed and active if a user hovers over a specific product/ID displayed on the page, the extension retrieves related vendor data about the product with the ID.
This is how I thought about this:
Use jQuery attr to access the ID on mouse over.
Post this ID to a retrieve.php file with .post() method
The retrieve.php file retrieves the data from database
Display the data in a tool tip on the web page.
I have some queries for the above process:
I am able to get this working on a local XAMPP server but how will it work online as the chrome extension will not have access to server. What is the way around to retrieve data without using PHP?
I am able to get the logic working but am unable to place these in respective files - Will all my logic reside in background.js ?
Any suggestions on getting this started will be much appreciated.
You could build a very simple API on your server that responds with JSON to any request it receives after processing it. Like this:
{"firstVar":"foo","secondVar":"bar" }
Your chrome extension can then make an xmlhttp request to this server and and process the returned data.(You could also use JSONP and wrap the response in a callback function which will execute as soon as you have the reponse)
The JS extension will be able to deal with the JSON nicely as it can understand that format so you can then choose to display the data in whatever way you want.
Essentially, what you want is a server that can take an ID posted to it and return the corresponding date in a nice and readable format. And a chrome extension that can make an request to a server and then process the response. Build and test them separately (keep positing an ID to the server and see the response and for your JS side at first instead of making requests to your unfinished API just set a static response to begin with which will be the same as an expected response.
I was wondering how do popular mail websites handle / call the serverside scripts. How do they do it differently in a way that users are not easily able to decipher which file they are calling to invoke say login authentication.
For eg: from yahoo website i did view source on login page and saw
<form method="post" action="https://login.yahoo.com/config/login?" autocomplete="" name="login_form" onsubmit="return hash2(this)">
usually action is the server side script file which is being called on submit button right? so they are redirecting to some other website on .done (i.e after authentication), but how do we know what file they calling to run the script?.. Where is the username and password. I tried a wireshark capture too, because they are using post, i won't see the username/password in the url but in wireshark i should see right?
Sorry a lame question, but was just curious as to how these big people work.
Are you merely confused about the URL https://login.yahoo.com/config/login??
Consider: A web server does not need to work with files at all. Having a URL like http://example.com/login.php is merely an extremely lazy way to map to a file on disk. Internally, the web server will receive the request as /login.php and will have to look through its configuration if there's a file login.php somewhere in a directory configured for the host example.com, execute that file and send back the results to the user. That's a complicated task.
Instead it could just receive the query for /config/login? and do something completely different with it, like... logging you in.
You're never executing files directly on a remote server. This is important. There's always a program translating URLs to executable programs or actions. This is completely arbitrary and has nothing to do with the file system.
Try searching for "pretty URLs".
The /config/login? in this case is just a entry point into the server at login.yahoo.com. It could be a HTTP handler name, and when that handler gets invoked on that webserver, it just calls into some other server side call (c++ or java or anything else)...
So its kinda hidden from you. They are (possibly) just executing a 'method' or a series of methods on the server side...which on completion return some data back to the browser via the same http handler/entry-point.
These server entry points or HTTP handlers get all the data from the browser when that form is post'ed and is forwarded to the actual handler for this call.
Search for HTTP handler modules.