Writing and using php streams and sockets tek11

 Idea originating in 1950’s
 Standard way to get Input and Output
 A source or sink of data
Definitions

 C – stdin, stderr, stdout
 C++ iostream
Who uses them

 Perl IO
 Python io
 Java
 C#

These are the people you can blame for the PHP streams implementation

 We will write code (in pairs)
 There will be a quiz (with prizes)
 You get out what you put in – participate!

This is really 3 talks in one -
 Streams
 Filters
 Sockets

 Access input and output generically
 Can write and read linearly
 May or may not be seekable
 Comes in chunks of data

 EVERYTHING
 include/require _once
 stream functions
 file system functions
 many other extensions

Stream
Contexts

Stream Stream
ALL IO
Filter Wrapper

 Stream
› Resource that exhibits a flow or succession of
data
 Wrapper
› Tells a stream how to handle specific
protocols and encodings
 Context
› A set of parameters and options to tell a
stream (or filter) how to behave

 Scheme
› The name of the wrapper to be used. file, http, https, ftp,
etc.
 Target
› Depends on the wrapper, filesystem uses a string path
name, ssh2 uses a PHP resource

home/bar/foo.txt
file:///home/bar/foo.txt
http://www.example.com/foo.txt
ftp://user:pass@ftp.example.com/foo.txt

php://filter/read=string.toupper|string.rot13/resource
=http://www.example.com

 flock
 wrapper limitations
 non-existent pointers (infinite loops can
and will happen)
 error handling

 Parameters
 Options
 Modify or enhance a stream

 stream_context_set_param
 stream_context_set_option
 stream_context_create

 file://
 http://
 ftp://
 data://
 glob://

 SSL  Phar
› https:// › phar://
› ftps://  Zlib
› ssl:// › compress.zlib://
› tls:// › zlib://
 SSH  Bzip
› ssh2.shell:// › compress.bz2://
› ssh2.exec://
› ssh2.tunnel://
› ssh2.sftp://
› ssh2.scp://

 Pipes
 STDIN, STDOUT, STDERR
 proc_open
 popen

 php://stdin
 php://stdout
 php://stderr
 php://output
 php://input
 php://filter (5.0.0)
 php://memory (5.1.0)
 php://temp (5.1.0)

1. Get a Feed from Flickr -
http://www.flickr.com/services/feeds/

2. No curl installed, allow_url_fopen is on
3. Display however you would like

Grab the feed as xml, pop it through
simplexml, loop and display the output
to a webpage

 There are no interfaces
 Implement as though there were an
interface
 Seekable is optional
 Flushable is optional
 Directory support is optional

 fopen
 file_get_contents

Information

 Return true or false
 $this->context will have any context
metadata
Code

 fread
 fgets
Information
 etc…

 Return string data or false
metadata
Code

 fwrite
 file_put_contents

Information

 get in a string of data to deal with
 return how many bytes you wrote
Code

 feof
 fread
Information
 etc…

 Return true or false
metadata
Code

 fclose

Information

 Don’t return anything
 any cleanup should go here
Code

 fstat calls stream_stat
 EVERYTHING ELSE uses url_stat
 Good idea to do both

 Return an array of data identical to stat()

 stream_seek
 stream_tell

 stream_flush

 mkdir
 rmdir
 dir_closedir
 dir_opendir
 dir_readdir
 dir_rewinddir

 stream_lock
 stream_cast
 rename
 unlink

Create a custom wrapper for any kind of
network or shared memory storage you
want (except s3 which is way overdone)

Implement at least the basics – extra points
for more features

Wrapper for wincache (btw, porting this to
apc would be a breeze)

Does basics + seek + flush (since we’re
caching) + rename + unlink

No directories

Use Case land – when streams
make sense

 Data in s3
 Data locally during development
 Easy switch out if alternative storage is
ever desired
 Storing image files

 Existing Zend Framework Code
 Register the s3:// wrapper
 Use a configuration setting for the stream
to use for all images on the system

 Store and edit template files in a
database
 Have the snappiness of including from
disk
 Minimal Configuration

 db:// stream
 simple stream wrapper that looks for the
template in the db, and writes it to the
filesystem before returning the data
 The cached location is FIRST in the
include path, so if it fails, the db stream
gets hit

 Talk to mercurial (hg binary)
 hg communicates via command line
 continue to pipe additional commands

 Use proc_open to keep a pipe to the
binary going
 Pass commands through stdin pipe as
necessary
 Abstract this out to other binaries that
are used by the system

1. Name 3 Built in PHP streams.
2. What is a Context? A Wrapper? A
Stream?
3. How do you identify a stream?
4. Name two extensions that provide
additional PHP streams.

 http://php.net/streams
 http://php.net/filesystem
 http://ciaranmcnulty.com/blog/2009/04/
simplifying-file-operations-using-php-
stream-wrappers

Because everyone needs to rot13
a file they open on the fly

 Performs operations on stream data
 Can be prepended or appended (even
on the fly)
 Can be attached to read or write
 When a filter is added for read and write,
two instances of the filter are created.

 Data has an input and output state
 When reading in chunks, you may need
to cache in between reads to make
filters useful
 Use the right tool for the job

 string filters
› string.rot13
› string.toupper
› string.tolower
› string.strip_tags

 convert filters
› convert.*
 base64-encode
 base64-decode
 quoted-printable-encode
 quoted-printable-decode
 dechunk
› decode remote HTTP chunked encoding
streams
 consumed
› eats data (that’s all it does)

 bzip.compress and bzip.compress
 convert.iconv.*
 zlib.inflate and zlib.deflate
 mcrypt.* and mdecrypt.*

 Extend an internal class php_user_filter
 It’s not abstract…
 Yes that’s a horrible name
 Remember this pre-dates php 5.0
decisions

 onCreate
 basically a constructor
 Called every time PHP needs a new filter
Information
(on every stream)

 return true or false
Code

 php_user_filter
› $this->filtername
› $this->params
› $this->stream

 onClose
 basically a destructor

Information

 no return
Code

 MUST return
› PSFS_PASS_ON
› PSFS_FEED_ME
Information › PSFS_ERR_FATAL
 You get buckets of data and do stuff to
them
Code

 $in and $out are “bucket brigades”
containing opaque “buckets” of data
 You can only touch buckets and
brigades with the stream_bucket_*
functions
 You get a bucket using
stream_bucket_make_writeable

 Given a list of bad words (we’ll use the 7
bad words), write a filter to remove them
from text
 Given a commonly misspelled word, fix
the spelling in the text

 I only did the bad words one, and
created an extremely naïve regex that
stripped the “bad” words from whatever
text it finds.
 It buffers the entirety of the text before
doing the replacement – this could be
done by looking for word boundaries
and doing it piecemeal to improve
performance

1. What term is used to describe data
handling in filters?
2. Name two built in filters you should be
using and why.
3. What is the default mode filters are
appended with?
4. What is the difference between
appending and prepending a filter?

 http://php.net/filters

Putter about the network with me

 Socket
› Bidirectional network stream that speaks a
protocol
 Transport
› Tells a network stream how to communicate
 Wrapper
› Tells a stream how to handle specific
protocols and encodings

 Network Stream, Network Transport,
Socket Transport
 Slightly different behavior from a file
stream
 Bi-directional data

 Sockets block
› stream_set_blocking
› stream_set_timeout
› stream_select
 feof means “connection_closed”?
 huge reads or writes (think 8K)
 stream_get_meta_data is READ ONLY

 New APIS in streams and filesystem
functions are replacements
 Extension is old and not really kept up to
date (bit rot)
 Extension is more low level

 stream_socket_server
 stream_socket_client

 tcp
 udp
 unix
 udg
 SSL extension
› ssl
› sslv2
› sslv3
› tls

 Given two files of quotes, write a server
with PHP streams methods to return
random quotes, optionally allow client to
pick which file to retrieve quotes from
 Given a simple tcp server that will return
a random quote – make a client that
pulls quotes for users

 socket_server.php – uses
stream_socket_server and
stream_accept
 socket_client.php – uses
stream_socket_client and a bit of loop
magic to make a little “cli” app

1. How is a socket different from a stream?
2. What transports does PHP provide by
default?
3. Name the two most commonly used
stream socket functions.
4. How can a user add additional
transports to PHP?

 http://php.net/transports
 http://wikipedia.org/wiki/Unix_domain_s
ocket
 http://tools.ietf.org/html/rfc1122

 Set of interfaces for streams
 Improved based filter class
 Wrappers for chmod and touch
 More tests!
 Any you have?

 http://emsmith.net
 http://joind.in/3439
 auroraeosrose@gmail.com
 IRC – freenode – auroraeosrose
 #php-gtk #coapp

Writing and using php streams and sockets tek11

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