1. Martin Kruliš 19. 3. 2015 by Martin Kruliš (v1.0)1

2.  Low Level C-like API ◦ fopen(), fread(), fwrite(), fclose(), … ◦ Data are treated as strings  Note that per-byte processing is extremely slow  File-wide Operations ◦ fpassthru(), readfile() – whole file is spilled to the output ◦ file_get_contents(), file_put_contents()  Read/write the entire file to/from a string ◦ file() – reads entire file as an array of lines 19. 3. 2015 by Martin Kruliš (v1.0)2

3.  POSIX Based API ◦ Only partial functionality on non-POSIX OSes ◦ touch() – sets current time to a file ◦ tmpfile() – creates temporary file ◦ rename(), unlink() – unlink ~ delete ◦ mkdir(), rmdir() – make/remove dir  Synchronization Issues ◦ POSIX atomic operations (append, mkdir, …) ◦ Advisory file locking mechanism – flock()  Locks are bounded to processes, multi-threaded web server need not guarantee sync. between PHP scripts 19. 3. 2015 by Martin Kruliš (v1.0)3

4.  File Properties (Size, Type, Creation Time, …) ◦ Dedicated functions for some properties  filesize(), filetype(), filectime() ◦ Reading all properties at once  stat(), lstat(), fstat()  POSIX Access Rights (rwx) ◦ Testing functions  is_file(), is_readable(), is_writeable(), … ◦ Modification of rights and owner  chmod(), chown(), chgrp() 19. 3. 2015 by Martin Kruliš (v1.0)4

5.  Traversing Directories ◦ Iterative – opendir(), readdir(), closedir() ◦ scandir() – returns array with directory contents ◦ dir() – returns object of Directory class  Directory Paths ◦ glob() – expanding wildcards ◦ dirname(), basename() – get part of path ◦ pathinfo() – parses path and return components ◦ realpath() – converts symbolic to real path  Absolute path without links,./, and../ 19. 3. 2015 by Martin Kruliš (v1.0)5

6.  CSV Files ◦ Comma (semicolon) separated values ◦ API uses file handlers from fopen()  fgetcsv() – reads one CSV line  fputcsv() – writes one CSV line  INI Files ◦ Configuration files with “name = value” items ◦ parse_ini_file() – reads the entire file and yields an associative array  Optionally divides the data to sections 19. 3. 2015 by Martin Kruliš (v1.0)6

7.  ZIP Files ( *.zip ) ◦ Rather complicated (ZIP is multi-file container) ◦ Represented by ZipArchive class  Zlib – gzip library ( *.gz ) ◦ Similar functions to standard C-like API  gzopen(), gzread(), gzwrite(), gzclose(), …  BZip Library ( *.bz2 ) ◦ Similar to Zlib ( bzopen(), …)  Other libraries are available (RAR, LZF, …) ◦ TAR only as PECL extension 19. 3. 2015 by Martin Kruliš (v1.0)7

8. Martin Kruliš 19. 3. 2015 by Martin Kruliš (v1.0)8 When confronted with a problem, some people thinks: “Hey, I’ll use XML!” Then they have two problems…

9.  Parsing Process ◦ Loading XML from text file into memory structures  Simple API for XML (SAX) ◦ The document is processed sequentially ◦ Important “events” are reported to the user  Opening/closing an element, attribute found, …  Document Object Model (DOM) ◦ Tree-based structure with object oriented API ◦ Nodes of the tree represent elements, attributes, text content, …. ◦ More suitable for mutable documents 19. 3. 2015 by Martin Kruliš (v1.0)9

10.  XPath Query Language ◦ Inspired by filesys. paths (elements ~ directories) ◦ Various types of queries that yield  Boolean, number, string, or set of DOM nodes ◦ Quite expressive (num. operations, conditions, …)  XSLT Transformations ◦ XSLT describes transformation of one XML document to another (or to HTML, or to plain-text)  XSLT rules are stored in XML document ◦ Uses XPath for search queries ◦ Turing complete language 19. 3. 2015 by Martin Kruliš (v1.0)10

11.  XML Utilities in PHP ◦ SAX parser ◦ DOM API and parser ◦ XPath query engine (over a DOM API) ◦ XSLT processor ◦ PHP-specific Simple XML API (simplified DOM)  Most of the API is object oriented ◦ DOM is object oriented by design ◦ Simple XML is based on specific properties of PHP classes (e.g., iterators or magic methods) 19. 3. 2015 by Martin Kruliš (v1.0)11

12.  Event Driven Parsing ◦ The document is processed as a stream  In a single call of xml_parse() ◦ Important encounters are reported via callbacks  xml_set_element_handler()  xml_set_character_handler()  … 19. 3. 2015 by Martin Kruliš (v1.0)12 Example 1

13.  Document Object Model in PHP ◦ Set of PHP-native classes ◦ Implementing DOM 3 as defined by W3C  DOMDocument – entire XML document  DOMElement – tree node of one XML element  DOMAttr – attribute of an element  DOMNode – base class for all tree classes  DOMCharacterData – plain text contents  … 19. 3. 2015 by Martin Kruliš (v1.0)13

14.  Document Validation ◦ DOMDocument methods for validation  validate(), schemaValidate()  Automatic validation when the document is parsed  If validateOnParse == true  DOMXPath Class for XPath Search ◦ Operates on DOMDocument ◦ Search is performed by query() or evaluate() ◦ The result is either basic PHP type ( boolean, float, or string ) or DOMNodeList object 19. 3. 2015 by Martin Kruliš (v1.0)14 Example 2

15.  XSLTProcessor Class ◦ Uses libxslt external library ◦ Transformation rules are loaded from a DOM document or from a Simple XML Element ◦ Transformation input is a DOMDocument object ◦ The result is yielded  As a new DOMDocument object  String with serialized XML/HTML/text document  Directly to a file 19. 3. 2015 by Martin Kruliš (v1.0)15 Example 3

16.  Simplified DOM API ◦ Also loads the document into tree structure ◦ All nodes are SimpleXMLElement objects  Tree traversal is implemented by overloading class iterators and magic methods __get(), __set(), … ◦ The structure can be modified and saved ◦ Some advanced functions are also available  Integrated XPath query processor  Conversions to/from DOM structure 19. 3. 2015 by Martin Kruliš (v1.0)16 Example 4

17.  JavaScript Object Notation (JSON) ◦ Lightweight interchange format for structured data ◦ Based on subset of JavaScript language ◦ Otherwise language independent  Many parsers exist with frontends for many languages ◦ Intended for replacing XML in simple scenarios  Syntax ◦ Two basic structures: collections and lists ◦ Supports strings, numbers, bools, and null type ◦ Unicode safe 19. 3. 2015 by Martin Kruliš (v1.0)17

18.  JSON Example [ { "StudentId": 42, "Name": "John Smith" }, { "StudentId": 54, "Name": "Jane Johnson", "Graduated": true } ] 19. 3. 2015 by Martin Kruliš (v1.0)18 Ordered list Named collection Number (int) Unicode string Boolean literal

19.  JSON Functions ◦ json_decode() – JSON string -> object/array struct. ◦ json_encode() – serialize any PHP type (except resource) into JSON string ◦ json_last_error(), json_last_error_msg()  Customizing Serialization Process ◦ JsonSerializable interface ◦ Abstract method jsonSerialize() that converts object into anything that can be processed by json_encode() 19. 3. 2015 by Martin Kruliš (v1.0)19

20. Martin Kruliš 19. 3. 2015 by Martin Kruliš (v1.0)20

21.  PHP: Hypertext Preprocessor ◦ Not restricted only to (hyper)text ◦ HTTP with MIME can accommodate any content  Compressed packages (zip, tar.gz, …)  Application documents (PDF, …)  Images  Caveats ◦ PHP is text oriented  Binary data are represented as strings ◦ PHP is interpreted  Processing binary data might be slow 19. 3. 2015 by Martin Kruliš (v1.0)21

22.  GD Library ◦ The php_gd2 module ◦ Supports various formats (JPEG, GIF, PNG, …)  Working with Images ◦ Image is a resource $image = imagecreate(400, 300); ◦ Large variety of functions for manipulation ◦ Image is not compressed in internal representation ◦ Can be saved or written to output  imagepng(), imagejpg(), imagegif()  Corresponding MIME type needs to be set 19. 3. 2015 by Martin Kruliš (v1.0)22

23.  Functions ◦ Loading/saving supported formats ◦ Basic pixel operations ◦ Drawing simple geometric shapes  Lines, circles, polygons, … ◦ Text rendering  Built-in fonts, PostScript fonts, TrueType fonts ◦ Transformation and resampling ◦ Copying, alpha blending  Functions are version specific ◦ And time/memory demanding 19. 3. 2015 by Martin Kruliš (v1.0)23 Example 5

24.  Exchangeable Image File Format ◦ Metadata for photographs ◦ Extension of JPEG and TIFF containers  PHP API ◦ Read only functions ◦ exif_imagetype() – returns image type ◦ exif_read_data() – reads meta-data from image ◦ exif_thumbnail() – returns the image thumbnail (if present) as binary string 19. 3. 2015 by Martin Kruliš (v1.0)24 Example 6

25.  Cairo ◦ Fast 2D drawing library written in C ◦ Supports transformations and Bezier curves  Gmagic ◦ A Swiss army knife for image manipulation ◦ Large variety of supported formats  ImageMagic ◦ Well established library for image manipulation ◦ Designed even for more complex operations 19. 3. 2015 by Martin Kruliš (v1.0)25

26. Martin Kruliš 19. 3. 2015 by Martin Kruliš (v1.0)26

27.  MySQL Revision ◦ Original mysql API is deprecated (as of PHP 5.5) ◦ MySQL Improved (mysqli) API  Dual object/procedural interface  Procedural interface is similar to original (deprecated) API  Advanced connectivity features  Persistent connections, compression, encryption  Directly supports transactions ◦ MySQL Native Driver (mysqlnd) extension  More direct access to MySQL server  Additional features (e.g., asynchronous queries) 19. 3. 2015 by Martin Kruliš (v1.0)27

28.  MySQLi API ◦ mysqli class – the connection to the DBMS  Manage controls, settings, info, stats, …  Issue queries and multi-queries  Performs transaction control ◦ mysqli_stmt class – SQL statement representation  SQL statement preparation and configuration  Argument bindings ◦ mysqli_result class – SELECT result wrapper  Various methods for accessing data in the result 19. 3. 2015 by Martin Kruliš (v1.0)28

29.  Extensions ◦ mysqlnd_qc  Transparent cache for MySQL queries ◦ mysqlnd_memcache  Special extension that utilizes InnoDB Memcache  Translates SQL statements to Memcache protocol ◦ mysqlnd_uh  Allows user to insert hooks for low-level calls  Can be used for monitoring or auditing ◦ mysqlnd_mux  Transparent client-side connection multiplexing 19. 3. 2015 by Martin Kruliš (v1.0)29

30.  PostrgreSQL ◦ Quite powerful alternative for MySQL ◦ Similar API to MySQL  pg_connect(), pg_query(), …  SQLite ◦ SQL engine running directly on filesystem ◦ Small project, where regular DBMS is not available  Commercial Giants ◦ MSSQL, Oracle, dBase, IBM DB2, … 19. 3. 2015 by Martin Kruliš (v1.0)30

31.  Abstract Database Layers ◦ Solving the problem of portability  If the application refrains from using specific SQL statements  PHP Data Objects (PDO) ◦ Generic interface for various RDBMS ◦ Extension php_pdo, individual DB systems are in separate extensions ( php_pdo_mysql, …) ◦ Simple object oriented API  PDO and PDOStatement classes  Minimalistic, no special functions 19. 3. 2015 by Martin Kruliš (v1.0)31

32. 19. 3. 2015 by Martin Kruliš (v1.0)32