There is a common misunderstanding, that mb_ereg_* functions are just unicode counterparts of ereg_* functions: slow and non-powerful. That’s as far from truth as it can be.

mb_ereg_* functions are based on oniguruma regular expressions library. And oniguruma is one of the fastest and most capable regular expression libraries out there. Couple of years ago I made a little speed-test.

Anyway, this time, I was going to tell about it’s usage. PHP-documentation isn’t telling much.

Let’s start with the basic fact: you don’t need to put additional delimeters around your regular exprsssions, when you use mb_ereg_* funcitons. For example:

// find first substring consisting of letters from 'a' to 'c' in 'abcdabc' string.
mb_ereg('[a-c]+', 'abcdabc', $res);

To execute same search, but in case-insensitive fashion, you should use mb_eregi()

mb_ereg(), mb_eregi() and mb_split() functions use pre-set options in their work. You can check current options and set the new ones using mb_regex_set_options() function. This function is parametrized by string, each letter of which means something.

There are parameters (you can specify several of these at the same time):

• ‘i’: ONIG_OPTION_IGNORECASE;
• ‘x’: ONIG_OPTION_EXTEND;
• ‘m’: ONIG_OPTION_MULTILINE;
• ‘s’: ONIG_OPTION_SINGLELINE;
• ‘p’: ONIG_OPTION_MULTILINE | ONIG_OPTION_SINGLELINE;
• ‘l’: ONIG_OPTION_FIND_LONGEST;
• ‘n’: ONIG_OPTION_FIND_NOT_EMPTY;
• ‘e’: eval() resulting code

And there are “modes” (if you specify several of these, the LAST one will be used):

• ‘j’: ONIG_SYNTAX_JAVA;
• ‘u’: ONIG_SYNTAX_GNU_REGEX;
• ‘g’: ONIG_SYNTAX_GREP;
• ‘c’: ONIG_SYNTAX_EMACS;
• ‘r’: ONIG_SYNTAX_RUBY;
• ‘z’: ONIG_SYNTAX_PERL;
• ‘b’: ONIG_SYNTAX_POSIX_BASIC;
• ‘d’: ONIG_SYNTAX_POSIX_EXTENDED;

Descriptions of these constants are available in this document: API.txt

So, for example, mb_regex_set_options(‘pr’) is equivalent to mb_regex_set_options(‘msr’) and means:

• . should include \n (aka “multiline-match”)
• ^ is equivalent to \A, $ is equivalent to \Z (aka “strings are single-lined”)
• using RUBY-mode

By the way, that is the default setting for mb_ereg_* functions. And, mb_ereg_match and mb_ereg_search families of functions take options-parameter explicitly.

So, back to functions:

// make sure, that the whole string matches the regexp:
mb_ereg_match('[a-c]+', $user_string, 'pz'); // 'pz' specifies options for this operation
                                             // (multiline perl-mode in this case)

// replace any of letters from 'a' to 'c' range with 'Z'
$output = mb_ereg_replace('[a-c]', 'Z', $user_string, 'b'); // use basic POSIX mode

Ok, these were easy and similar to what you’ve seen in preg_* functions. Now, to something more powerful. The real strength lies in mb_ereg_search_* functions. The idea is, that you can let oniguruma preparse and cache text and/or regexp in its internal buffers. If you do, matching will work a lot faster.

mb_ereg_search_init($some_long_text); // preparse text
mb_ereg_search('[a-c]'); // execute search
while ($r = mb_ereg_search_getregs()) { // get next result
    // work with matched result
}

mb_ereg_search('[d-e]'); // execute different search on the same text

mb_ereg_search_init($some_other_text); // preparse another text
mb_ereg_search(); // execute search using previous (already preparsed) regexp

This is the fastest way of parsing large documents in php, as far as I know.

Notes on charsets. Though, it is often mentioned, that mb_ereg_* functions are “unicode”, it would be more practical to say, that they are encoding-aware. It is a good idea to specify, which encoding you use beore calling oniguruma.

Some options:

mb_regex_encoding('UTF-8');
mb_regex_encoding('CP1251'); // windows cyrillic encoding
mb_regex_encoding('Shift_JIS'); // japanese

Check the full list of supported encodings.

Now, some of my readers, are probably asking themselves: what is it all about? why is this bug important? Ok. Let’s find out!

How does browser usually find which server to ask, when you enter URL? Well, at first, it parses out protocol and domain name from URL. For example, if URL is http://www.example.com/page.html then protocol is http and domain name is www.example.com. After that, browser sends request for “A” type record to DNS server and server replies with IP address (or several IP addresses). After that, browser tries to open connection with these addresses one by one, until it finds one which really works. Hopefully, first one will work, but sometimes each one will fail; In this case, browser will show us an error.

“A” records have the following format:

    hostname    IN  A   ip-address  time-to-live

For basic cases, this scheme seems to work just fine, but it has some inherent flaws, when you start to think about scalability.

1. It is impossible to map different services on the same domain-name to different servers. For example: I can’t have FTP and HTTP servers responding on example.com and, at the same time, located on different physical machines. My only option would be some kind of router, which would forward requests on different ports to different IP’s.
2. It is impossible to map service to specific port of server. Browsers just looks for TCP-connection on port 80 while using HTTP, for example.
3. It is impossible to implement sophisticated load-balancing rules in DNS. Having several A-records in DNS just gives possibility to have equal-load of several machines, nothing fancy.

It is an interesting fact, that all this problems are solved long time ago for one specific protocol called SMTP (yes, the one which delivers emails all around the globe). SMTP uses special kind of DNS-records called “MX” which allow to specify which machine(s) are waiting for SMTP-connections targeted to domain name and allow to specify priority of these machines, so, at first, clients will try to access machines with high priority and in case of problems will fallback to low-priority ones. So, MX records make email-infrastructure seriously more robust and scalable then anything else. Why such special treatment?

“MX” records have the following format:

    domainname  IN  MX  priority    hostname  time-to-live

Here, RFC 2782 comes on scene. Idea of this standard is to achieve similiar flexibility for any protocol used on internet.

“SRV” records allow to specify that specific application protocol, used over specific transport protocol of this domainname is handled by several servers on specific ports with various priority. That is as flexible as it can be. Let me throw some examples:

    _http._tcp.example.com. 86400 IN SRV 0 5 81 www1.example.com.
    _http._tcp.example.com. 86400 IN SRV 0 5 80 www2.example.com.
    _http._tcp.example.com. 86400 IN SRV 1 9 81 www-backup.example.com.
    _http._tcp.example.com. 86400 IN SRV 1 1 8000 www-weak-backup.example.com.

These four records tell browser, that:

• HTTP-over-TCP connections for “example.com” domain are handled by 4 servers: www1.example.com on port 81, www2.example.com on port 80, www-backup.example.com on port 81 and www-weak-backup.example.com on port 8000.
• www1.example.com and www2.example.com have priority “0″ (highest), so should be first to try. Both have weight “5″, which means, that they have 50% chance to be selected by client (equal load)
• In case both of these are not reachable, browser should check lower-priority servers www-backup.example.com and www-weak-backup.example.com, but www-backup.example com should be preferred in 9 out of 10 cases (it has weight=9, while another one has weight=1).

Sounds pretty cool, but, unfortunately, this technology is still not implemented in any of the browsers. Mozilla(Firefox) has this bug for 10 years, WebKit has this bug for 3+ years and Chromium has this bug since today.

There is no need for special support on webserver-side — that’s a good side of this technology too. Just add relevant records to DNS-server and all compliant clients will see it.

At the moment, SRV-records are widely used by XMPP/Jabber, SIP, LDAP software and Kerberos. I believe, any protocol in use can benefit.

Often, while working on software projects, one finds, that there are repetitive tasks, which would be much easier to deal with, if automated. In the C/Unix world, this task is often solved by Make, Java programmers prefer Apache Ant, Ruby programmers use Rake. The fact, which is not commonly known, is, that PHP also has such instrument, and it is called Pake. It was originally created by authors of Symfony framework. Unfortunately, they never wrote any documentation, which killed adoption rates.

To start automating something, you need to create Pakefile.php in the root-directory of your project, define some tasks inside and run them with “pake taskname” from command-line. The good news is, that tasks are defined in PHP language and syntax is quite simple:

I defined 3 rules, gave them descriptions and specified dependencies. Additionally, I specifed default rule. Now, we can play with this a bit. Create file with this contents, save it somewhere, and point your terminal to the same directory.


> pake
baz
bar
foo


What happened? Pake looks for “default” task in the pakefile. We defined “foo” as default. Pake found out, that foo depends on bar, and bar depends on baz. So, Pake runs “baz”, then “bar” and then, finally, “foo”. That is as simple as it can be.

Pake has builtin support for basic file-operations (pake_mkdirs(), pake_copy(), pake_rename(), pake_remove()), which are the powered-up versions of php’s filesystem-functions, templating (pake_replace_tokens()), directory-mirroring (pake_mirror()) and runners for creating PEAR-packages, Phing-commands and Simpletest.

Pake project wasn’t maintained for a while, so I decided to give it a spin (as there is a good chance, that I will be able to use it for my current projects). I imported it’s version history to GitHub. You can find latest version here: http://github.com/indeyets/pake

My plan is to add some generally usable helpers to current branch, write some documentation and then to start work on Pake2 which would use all new features of PHP-5.3 (namespaces, closures, rich SPL).

Git-project is a source for creating pear-package. To build one use the following command:


> php bin/pake.php release 1.1.0a1


it will create “pake-1.1.0a1.tgz” file in the same directory. You can install it with the following command:


> pear install -f pake-1.1.0a1.tgz


If you want to grab a prebuild pear-package of pake, you can do it here

Here’s the description from Twitter Data site:

Twitter Data is a simple, open, semi-structured format for embedding machine-readable, yet human-friendly, data in Twitter messages. This data can then be transmitted, received, and interpreted in real time by powerful new kinds of applications built on the Twitter platform. Here is an example Twitter Data message:

I love the #twitterdata proposal! $vote +1

The part with the dollar sign, $vote +1, is a piece of data embedded using the Twitter Data format.

To use php-twitterdata library, download it into the sub-direcory in your project’s directory (or any other place you like) and init the autoloader:

PHP API provided by php-twitterdata has 2 layers. On lower level, there are 3 classes: TwitterData_Message, TwitterData_Frame and TwitterData_Tuple which correspond to parts of data-enabled twitter-message. Message can consist of several Frames, Frame can consist of several Tuples and a “subject”. Objects of each of these classes can be created programmatically and combined in hierarchy. Each of them has “magic” __toString() method, so, to export them as a valid twitter-message, you just need to put objects in string context. Something like this:

and the result will be:

Hello, world! $foo bar


If you need to parse Twitter Data messages you should use TwitterData_Parser class. It is a SAX-style parser, with DOM-style export. If all you need is a hierarchy of objects, use it like this:

Otherwise, you can specify another handler-class as a second parameter of constructor. Such class has to implement TwitterData_Parser_CallbackInterface.

Does it all sound too complex? No problem!

php-twitterdata library also includes high-level interface, which consists of 2 simple functions: TwitterData::array_to_TwitterData() and TwitterData::TwitterData_to_array(). First one converts associative array into the string, which can be inserted into twitter-message, and second one takes message-string received from twitter and returns associative array parsed out of tuples from the first frame of message (If you need to get all possible data from message, you will still need to use low-level API).

Example of high-level API:

Library has unit-tests, which cover all examples provided on Twitter Data site both on Introduction page and on Examples page and is licensed under MIT-style license.

PHP-FPM is “deciphered” as “PHP FastCGI Process Manager” and is a patch for php to greatly improve FastCGI SAPI usage in production. It adds a bunch of additional features to php’s fastcgi such as: easy php-process daemonization (with ability to specify uid/gid/chroot/log-file), safe php-processes restart (without losing requests), custom error-handling and accelerated file-upload support (requires additional support from web-server).

There’s not much documentation in english, currently, but, again, there is a good chance that it will be added really soon.