We've been thinking on writing a php interpreter for a project we've been working on. Interpreting aside, I've been trying - with no success - to find how the PHP interpreter interfaces with the http server. So I've come to you, o' dear knowledgeable people of Stack Overflow.
I have read that php listens on localhost:9000. Goes without saying that I tried to connect to that and it was no use. Maybe the webserver runs "php file.php" and gets the output?
Also, could a php interpreter that interprets .php files and our interpreter (lets call it pqp for the sake of argument) that interprets .pqp files coexist in a single webserver?
Thank you very much!
There are certain ways in which PHP interacts with a webserver. One is indeed to pipe PHP files into the PHP cli and serve the output as in this question. As I wrote there: It's really not recommended.
The next best thing is to expand the sapi of PHP, which is providing a set of connectors to a webserver. In this case, PHP is going to act like a webserver module (see apache+mod_php). A downside of this is that PHP is trying to parse everything it gets its hands on.
A webserver-independent method is to connect to PHP via the Common Gateway Interface, whcih is a well-defined interface for various interactive serverside components. It is, however, terribly slow (and a bit insecure).
The final step is to implement FastCGI. This is an improvement over CGI in that it tries to connect to a running process. In the PHP world, this is achieved through php-fpm which (by default) indeed listens on 9000/tcp.
Related
My LAMP server is CentOS 7.4 with Apache 2.4, PHP 5.4, and Python 3.6.
I am new to Python; I migrated from R to Python just now. I need some Python package to do statistics, and then deliver the output to PHP.
I reviewed lots of similar questions. The answers are around exec(), passthru(), system(), and shell_exec(). They are dangerous commands and should not be enabled in PHP.
In the Python official manual, "Integrating Python With Other Languages", mentioned are only two tools, ppython and PHP "Serialize" in Python.
ppython seemed no longer maintained, but that's what I need, just like Rserve when I use R.
I also read this post:
Simple and standard solution is using Socket or Webservice(API)
Now, how do I run a Python script in PHP without using exec(),system()...(maybe socket communication)?
Everything is dangerous (even a fork) if you don't know how to use it. Well, you have several options:
Standard: Running the Python interpreter in PHP with exec() / shell_exec(), etc. Plus there will be a small latency and ability to run Python compiled byte-code, so performance wins here.
Non-standard: If you are concerned a lot about security issues at hand I suggest better to insert Python commands into some batch table and run these regularly with the CRON scheduler. After execution, fetch results with PHP. In this way PHP / Python execution will be de-coupled and you will have a better control on how / when to execute Python scripts.
Non-standard (avoid at all costs): Your mentioned project is moved to Git at php-python. It simply starts a new Python server on port 21230 and waits for Python commands from a PHP scripts. Now, THESE solutions are a most dangerous one, because of the additional opened port in the web server, which is a big headache to administrators and thus highly not recommended.
The last option is to question an assumption that Python is needed at all in web development of PHP. The more different languages in the company IT farm - the harder it will be to maintain all sources and harder to beat time-to-market of new features / bugs fixing. So before considering execution of Python script(s), at first think about re-writing them to plain PHP.
You can do it automatically, but these type of translators are very error-prone and incomplete - for example this one doesn't supports imports. (What the hell? Python without imports is like a bread without a flour). The second option is to learn Python and re-write code at hand into PHP. Or simply get a customer requirements and code these into PHP. Everything that can be done in Python, can be done in PHP too (at least in web development perspective).
Convert your Python script to the Django REST API, and then call it using cURL.
Guys recently I decided to go back to PHP and do some more complex stuff than a simple log in page. For 3 years I've been programming with Java/JavaEE and have a good understanding of the architecture of of Java Applications. Basically, a virtual machine ( a simple OS process ) that runs compiled code called byte code. a simple Java web server is basically a java application that listens on provided TCP port for Http requests and responds accordingly of course it is more complicated than that but this is its initial work.
Now, what about PHP ? How does it work ? What, in a nutshell, is its architecture.
I googled about this question but in 90% the articles explain how to implement and construct a web application with PHP which is not what I am looking for.
The biggest difference between a Java web server and PHP is that PHP doesn't have its own built-in web server. (Well, newer versions do, but it's supposed to be for testing only, it's not a production ready web server.) PHP itself is basically one executable which reads in a source code file of PHP code and interprets/executes the commands written in that file. That's it. That's PHP's architecture in a nutshell.
That executable supports a default API which the userland PHP code can call, and it's possible to add extensions to provide more APIs. Those extensions are typically written in C and compiled together with the PHP executable at install time. Some extensions can only be added by recompiling PHP with additional flags, others can be compiled against a PHP install and activated via a configuration file after the fact. PHP offers the PEAR and PECL side projects as an effort to standardise and ease such after-the-fact installs. Userland PHP code will often also include additional third party libraries simply written in PHP code. The advantage of C extensions is their execution speed and low-level system access, the advantage of userland code libraries is their trivial inclusion. If you're administering your own PHP install, it's often simple enough to add new PHP extensions; however on the very popular shared-host model there's often a tension between what the host wants to install and what the developer needs.
In practice a web service written in PHP runs on a third party web server, very often Apache, which handles any incoming requests and invokes the PHP interpreter with the given requested PHP source code file as argument, then delivers any output of that process back to the HTTP client. This also means there's no persistent PHP process running at all times with a persistent state, like Java typically does, but each request is handled by starting up and then tearing down a new PHP instance.
While Java simply saves persistent data in memory, data persistence between requests in PHP is handled via a number of methods like memcache, sessions, databases, files etc.; depending on the specific needs of the situation. PHP does have opcode cache addons, which kind of work like Java byte code, simply so PHP doesn't have to repeat the same parse and compile process every single time it's executing the same file.
Do keep in mind that it's entirely feasible to write a persistent PHP program which keeps running just like Java, it's simply not PHP's default modus operandi. Personally I'm quite a fan of writing workers for specific tasks on Gearman or ZMQ which run persistently, and have some ephemeral scripts running on the web server as "frontend" which delegate work to those workers as needed.
If this sounds like a typical PHP app is much more of a glued-together accumulation of several disparate components, you'd be correct. Java is pretty self-contained, except for external products like RDBMS servers. PHP on the other hand often tends to rely on a bunch of third party products; which can work to its advantage in the sense that you can use best-of-breed products for specific tasks, but also requires more overhead of dealing with different systems.
This is how does PHP work:
(one of the best over the Internet)
In general terms, PHP as an engine interprets the content of PHP files (typically *.php, although alternative extensions are used occasionally) into an abstract syntax tree. The PHP engine then processes the translated AST and then returns the result given whatever inputs and processing are required.
Below image will depict more information
Source: freecodecamp.org
Building a PHP script that responds to an Ajax request is as easy as:
<?php
$command = $_POST["command"];
if ($command == "say_hello") {
$name = $_POST["name"];
echo json_encode(array("message" => "Hello, " . $name));
}
?>
and, at least if you're using jQuery on the client side, and if you specified a callback function on the original request, the array containing the message will be passed into that callback function.
But with Python it's not that simple. Or at least I haven't figured out how to make it that simple. If I just try to "print" a response (paralleling PHP's "echo" statement above) the client doesn't get anything back.
Whenever I've looked on the internet for how to respond to an Ajax request with Python, the answer always involves using Django or some other web framework.
And I know those things are great, but what is PHP doing that makes using a similar package unnecessary? I would like to be writing my server-side script in Python instead of PHP, but I'd prefer a D.I.Y. approach to using a third-party framework for what should be (right?) a pretty simple task.
Any help? An example of how to do this would be much appreciated.
But with Python it's not that simple. Or at least I haven't figured out how to make it that simple. If I just try to "print" a response (paralleling PHP's "echo" statement above) the client doesn't get anything back.
I might have some of the details wrong, but I'll try to explain why this is the case. Firstly, the PHP you're talking about is baked directly into the apache webserver. When you do an echo, it outputs the result to the response stream (a TCP connection between the server and client). When you do print in python, what you're doing is outputting the result to standard out (the command line).
How most languages work with the web, is that a request comes in to some kind of web server, and that web server executes a program. The program is responsible for returning a stream, which the webserver takes, and streams to the client over the TCP connection.
I'm assuming that the webserver redirects PHPs standard out to the webservers stream, and that is how PHP is able to use echo to return its result. This is the exception, not the rule.
So, to use python to serve requests, you need to have a webserver that can execute python in some way. This is traditionally done using CGI. More recently, something like mod_python was used to host the python within apache. Nowadays, wsgi or mod_wsgi is used, which is the standard defined for webservers talking to python.
You might want to look at something like web.py, which is a minimalist python web framework. This will get you very very close to what you're trying to do.
PHP was built with the web in mind from the very beginning. In contrast Python was designed as a general purpose language.
When you echo from PHP you're actually writing to a stream that is sent to the user as part of an HTTP response. When you do a print in python the output, by default, is written to the stdout stream which means instead of being sent to the user over http the output is written to the console (or whatever is capturing stdout at the moment).
So to PHP, HTTP is a first class citizen. To more general purpose languages like Python, Ruby, Erlang, C, C++, and so many other languages. You have to communicate to HTTP in different ways. PHP already handles that communication through apache's mod_php or through something like PHP-FPM.
Sooo....
As far as creating your own server side script, I'd highly suggest against it as Python's Frameworks take the place of the layer that PHP is built on. So creating a standards compliant http server on your own with Python isn't going to be very simple. The reason that this is so hard is that you'd either have to interface with CGI or WSGI (a Python standard for dealing with the web) or create your own HTTP server. If you think you're up to the task then I highly suggest it! You'd probably learn a whole lot by doing it, but it isn't going to be the easiest thing. The great thing is that so many libraries already take care of this communication for you. For example, if you're looking for something lightweight, I highly suggest a micro-framework like flask which is one I personally use if I need something very simple. It is much easier to get started than django, but it also has less batteries included.
Hope this helps!
There is a python module called json. Perhaps so many of the answers deal with frameworks (like Django) because json is web-centric and Django, tornado, twisted, cherrypy, etc. all are the means by which python interacts with the web.
There are many different ways to do this, and those are addressed in other questions. However, to just answer your question, python has a json library in its standard library.
Most PHP installers configure themselves by default to serve php files in web directories by running the script. Most Python installers do not. Quickest way to serve Python with apache:
In your apache config file, add AddHandler cgi-script .py to whatever block can already serve PHP files
shebang your python scripts by adding #!/usr/local/bin/python or whatever path python is on in your system
remember to print headers first, followed by a newline, then body.
use import cgi if you want to do anything more complicated than sending back a response body.
Note that this is not the recommended way to run a python website, just the fast, php-ish way.
Richardhsu has the gist of it correct.
Essentially python is a general purpose scripting language. As such, it needs a way to connect to the web, such as by opening a port and doing network programming etc. You can also use something CGI to attach to apache or other web server.
This is really no different then how Java, Ruby, Perl or C/C++ get to the web either. In fact, PHP does much the same thing. It's interface to the web server is just tighter then CGI.
If you were to have PHP interpreted from the command line, or compiled, then you would have the exact same issues that you do with Python now. The issue isn't PHP vs Python, it's how you get the scripting language of your choice attached to the internet using the HTTP protocol.
I have a C# application that needs to call a PHP script, and get the output, in the fastest possible way. The options I explored:
Executing the script with PHP CLI (Pro: Easy / Cons: No Opcode Cache / Precompilation ]
Compiling the PHP (Phalanger, Hiphop, etc.) [Pro: No Webserver / Con: Compatibility ]
Using an embedded webserver (AppWeb, Cherokee, Lighttpd) [Pro: Simple / Cons: Deployment ]
Are there any other options left?
EDIT: The best possible option would be to make use of the build-in FastCGI server of PHP, by running php-cgi.exe -b 127.0.0.1. But there seems no (C#) code to talk to a server available. While there are so many server-side libraries (like FCGIDotNet and SharpCGI), they all implement the server-side of the protocol.
One other option could be to run the PHP CLI script as a daemon (good blog post on this here).
If the script has a particularly long startup/cleanup, then running it as a daemon would mean that you only do this once.
The downside is that you'd need to write a way of communicating with that daemon, to get the data from C# to it. You'd also need to keep an eye out on its memory usage over time.
The best method is always going to be specific to your script though.
As you may know, PHP originally stood for "Personal Home Page", it is now said to stand for "PHP: Hypertext Preprocessor", which literally states it's usage, and basically is not something that a developer would embed into his application just to have a scripting option.
Unless you have some really specific piece of software and strong arguments, I'd suggest you to stick to Lua, or similar scripting libraries which are easy to embed and maintain. Otherwise, use it the way as everyone is using it, CLI. Or else be prepared to face the consequences.
I'm writing a web server in C, and I need to figure out a way to use CGI to execute dynamic content server-side.
I'm looking at the FastCGI protocol and it looks annoying. It reminds me of the bit twiddling I had to do in a class when I was converting ASCII to UTF-8 and back (that seemed useless then, but maybe it wasn't...)
I found a great library written in PHP where I could just start up php-cgi -b localhost:8888 and start communicating with it. Obviously, I'd like that in C.
I'd appreciate it if someone could find a library (for FastCGI clients!). If not, then I'm fine with contributing to the open source community by writing one.
Also, how exactly do I use SCGI? There's barely any documentation on it (that I can find, anyway). What socket do I connect to? Where do I send the requests?
Also, php-cgi is only for PHP, so how do things work for Perl, Python, etc?
Thanks again.
mario said (in the question comments):
There are a few libraries mentioned on the FastCGI homepage. http://fastcgi.com/drupal/node/5. The development kit should include the server.
The client implementation is included there for, too. http://fastcgi.com/devkit/doc/fcgi-devel-kit.htm
SCGI http://python.ca/scgi/protocol.txt is extremely simple to implement even without reference code.
You need an SCGI client that runs as deamon, and that accepts socket connections on an agreed port (4000 or 5000 seem common).
SCGI is no different than FastCGI. Each language would require its own daemon, you can run multiple. And accepting CGI requests is pretty much what they do. The only difference is the socket and the header format instead of a CGI stdin pipe and env variables.
To this I'd like to add: CGI (which is exactly what the question asks for) is different from FCGI and SCGI in their working models. It's quite easy to mistake one for others. Luckily, it seems like Preetam asked for FCGI and SCGI.