I'm new in this subject so this might be a silly question for most of you. I have a simple server which several users will access. If any of them change a CSS property of an element, the others should be able to see the change in real time.
Should I use something like node.js to perform this? How do I save the changes the users do?
The page would look something like this: http://stom89.dyndns.org/
Thanks!
I guess what you want to change in your CSS / html , are states. Like if a lamp is on/off? Then you need to save each state in a mySQL DB and just grab the data for each user. If you want it to look like realtime for online users, then use js(ajax) to sync data regularly.
Alternative way without a DB would be with files.
If you don't wanna use mysql for this, you can use files. I suggest using ini files. For more on how to read/write ini files, you can visit this question. It's super simple and you'll be able to have each variable in a nifty array.
What you need: A bit of PHP, a little bit of jQuery (or js), understanding of GET variables
I suggest you create 3 files.
index.php :
Your main page which is the client. Pulls info using get
variables. You can use jQuery.get() for this.
getstate.php :
This is the file which will read the ini file and give you back the states for each device. Read them with jQuery.get() from index.php .
savestate.php:
This is the file which you'll send the new states to from index.php Example request: http://address.goes.here/savestate.php?bedroomlight=1&garagelight=0
Whats even more interesting is that ini files can be written/read easily by many programming languages so you can manipulate the data using your Raspberry Pi easily. (say someone turns of a light, a script polling state could change the ini file)
I think you would need to use a sql database and have a javascript to detect changes and update through AJAX. That's my best idea.
I have been messing with this subject for sometime if I completely understand your question. I would suggest looking at python, ruby or node.js though I could not say which is the easiest to learn for you though I would suggest python and a comet server which could be ape and simply have the server push the updates to the users that are already on the site.
Edit:
Suggestions for polling :: jQuery
http://api.jquery.com/jQuery.get/ for standard data retrieval which is about all you will need.
Related
I'm designing a website where users can upload comments on pages, and other users should see those comments. I reached the stage where I have the comments stored in a database, and I know the place they're supposed to go in the html, and I need to connect those two things somehow.
I'm using express and Node.js on the server side, and postgres on the db side.
As of when I'm asking this, it seems to me it's very bad practice to have the user access the database. So I think the server needs to access the database based on the user's request, modify the generalized html's showing of comments to now have the information of the specific comments, save that to a file, and send it to the user. To do this I was thinking of creating an "html generator function" on the server-side that takes in specific comment information and puts it in the generalized html, but that seems like it doesn't scale well and I'm concerned that storing the intermediate file would be inefficient.
Is that the correct approach? Can you tell me known ways of doing this that aren't so hacky?
If you suggest using php, isn't there a problem where php connects to a server and disconnects every time we use it? I would prefer if the server connected once when it booted and did all the fetching when needed instead of connecting every time. It seems to me like that would involve far less overhead (correct me if I'm wrong...)
See the comment of Amadan for the full solution. It's called a "template engine"
Edit:
I highly recommend learning React. I learned EJS and it's difficult to scale. React is infinitely easier to program with for just a little more investment. The old web is much less declarative (& EJS is much less too).
I have a editable html5 page and I store new elements in localStorage.
I want to synchronize my page with the server.
I want to know if I can do it without a server side script or if there is some tips to do something like this in a good way.
Thank you :)
You can pull information from the server quite easily using jQuery and then just put it on Local Storage but, if you want to upload local information to the server there is no way around, you have to use some kind of script, tough it's not that difficult, there are many languages (PHP, C#, Python...) and tools you can use.
Keep in mind that when you upload information to the server you have to sanitize it very important security measure.
Basically, the way to go is:
Post the information to the server (using AJAX or a HTML form, either way will do)
Use some server-side script to capture the variables posted.
Sanitize your data (check format, discard non-valid characters, etc)
Store it on database (Do not, ever, concatenate your data with a SQL query ok? that can make you vulnerable to a SQL injection attack), compute something or do stuff.
Return some status to the client (some confirmation maybe?)
You may want to take that confirmation and show a message to the user ("Your info was saved properly" or something like that)
is a javascript timer not sufficient for this manner? or jQuery?
The question really should be more of a problem than a question. If you're updating based on a server's variables then you could use AJAX i believe but if its like increment said variable every X seconds I would focus on using a javascript timer.
I am building a website with ROR 3. I need to provide a page to my clients wherein he could edit his pricing info regarding the application. I am quite confused on how to do this. The pricing page needs to be displayed as an html table with different columns which has got the pricing info.
I am thinking of different ways to do this.
1) Allow the client to create and upload an html page and then save it as a file in my public directory and render as an when the client clicks on the pricing link.
2) The clients may not have bare technical knowledge, hence make the client upload some other formats like Word, Excel etc and then parse it and store it as an HTML file in the public directory.
3) Provide the client with some real time editing tools where in the client could edit in a fixed format, and after wards save the file and render it later.
Also, I wouldn't like to store these infos in my database. There would be quite a few number of clients and hence managing all these data in my database would become cumbersome. Storing all these as plain html files and rendering it later would be the most ideal thing for me.
There might be other better steps in doing this as well. Could you please suggest which might the better, or any other option that could suit my needs? Basically I would want my clients to have a mechanism where they could provide there pricing details, edit it later and display it back as an html table, all this without using an Database backend. Any suggestions would be mostly appreciated.
Good way is Excel(csv format).
You can do PHP with Excel. I thing this is the best solutions for your requirement.
Try this.
http://php.net/manual/en/function.fgetcsv.php
If you are give authority to user to change edit contain and you have to used " CSV or Excel" please see these links:
Importing CSV and Excel
Exporting CSV and Excel
If you really don't want to use database then you can use YAML as a structured storage.
e.g. ( you, most probably, could come up with a better structure )
SMS_Pack:
Sl_No:
1: 10000
2: 25000
3: 50000
You can read those .yml files and parse them as hashes. Should be fairly easy to represent that hash as a HTML table.
For the creation, I'm sure you can come up with some dynamic form input. Or to just let the client send this kind of file ( which might not be the best solution ).
But it just might be easier to manage all of this information within a database.
My php script pulls about 1000 names from the mysql db on a certain page. These names are used for a javascript autocomplete script.
I think there's a better method to do this. I would like to update the names with a cronjob once a day (php) and store the names locally in a text file? Where else can I store it? It's not sensitive info.
It should be readable and writable to php.
Since you only need the data updated once a day, have a cron-script generate a static json file in some fixed location. Then read this with ajax on the client and make sure it caches it on the client.
Or potentially, generate the file whenever the database is updated (if this is applicable, I don't know your application)
You could try Memcache. But that could be like using a sledge-hammer to crack a nut.
Edit What about storing the data as simple file and let users (JavaScript) download it. Clients would not query the server for every key stroke because they could search for matching values themself. Format could be JSON because it is simple and JavaScript native.
It's unlikely reading from a text file will be much faster than a database query - MySQL already does a lot of caching that should make your query speedy.
If you need to make this query often and performance is a problem often you could consider using a caching module for PHP.
Related
The best way of PHP Caching
Im developing a new site, and I'd like to store my rewrite rules in a database, instead of right in the .htaccess files.
I have another site that uses Opensef (http://sourceforge.net/projects/opensef/) with a Joomla! installation that is doing this, but im not even 100% how it works underneath the hood.
How can I store these rules in a database, query for them on request and rediret to the clean URL if found? Is there a better way to do this instead of loading up a .htaccess file (there may be 1000's of entries)?
Thank you,
You can get mod_rewrite to generate a map from external source such as executing a PHP or Python file which can get the data from the database and create a mod_rewrite map.
http://httpd.apache.org/docs/2.0/misc/rewriteguide.html
(See right at the bottom)
For example
RewriteMap quux-map prg:/path/to/map.quux.pl
Good Luck
Assuming all these pages are ultimately in Joomla, I think using .htaccess or mod_rewrite is a mistake.
I think you're much better off learning how Openserf works. I'd imagine it has a little piece of code that runs early on for every request that queries the database and issues a Redirect through PHP if there's a hit. A further advantage of this approach is that it should even be possible to have Joomla rewrite links on its pages to point to the clean version in the first place, saving the user an unneeded redirect
Incidentally, this is how the Pathauto module in Drupal does it, and I use that all the time on some pretty high volume sites with many thousands of pages.
I think that the best approach to use rules stored in a database is:
Store the rules in your database through your admin panel of your site.
Then after updating database, generate a new .htaccess using the rules in DB using your server-side language solution.
Replace old .htaccess with new one.
This avoids the server load. It's similar to Aiden Bell solution.
Grab the UrlRewriteFilter, butcher it to use a DB, and use that in Tomcat instead of Apache.
Tomcat is a fine web server and can do many things Apache can do (like FastCGI for PHP), and writing stuff like this for it is trivial compared to writing such things for Apache.
What you probably want is a single rewrite rule to handle every unknown request that comes in and then pass that to a small script that will handle the lookups & generate redirects. You could even skip the rewrite rule completely and use the Apache ErrorDocument directive to pass unknown URLS into the script.
You've been pretty slim on the details of what this 'new site' is but, you might want to consider building yourself a Front Controller for the app & having it take care of all the incoming URLs. Many (most?) web app frameworks take this approach.