Creating Databases for Web Applications Work session Open Source versus Proprietary important topics HW: finish* projects. Look at final quiz guide. Final posting.

Final posting post your considered, reasoned opinion on Open Source vs proprietary; asp versus php; Access versus MySql; or any related issue. Catch up on other postings.

Postings: php vs asp, etc. Proprietary can be companies other than Microsoft. For example, Cold Fusion is product of Macromedia (formerly Allaire). Keep in mind that there are many topics, functions, relevant standards,etc. in these systems that we did not cover.

Things to consider … things to store away in the back of your mind for consideration when building a 'real' Web application.

Performance Performance of Web sites governed by connection AND site itself. –presence of large images, other large files, big consideration. Some DBMS provide for stored procedures that carry out a query. Sometimes these can involve parameters. This is a way to improve performance. The function is compiled and not interpreted. Some DBMS provide for (extra) index fields besides the primary key. This is another way to improve performance.

Important topics multiple (concurrent) users of database –DBMS may handle this. –single table versus multiple tables –transaction concept writing/updating across multiple tables paging –handling of large[r] recordsets

Important topics, continued scaling up application –multiple users; many, many users –larger tables maintenance of program –version control –backup databases scripts / code –data base administrator data dictionary –'quality assurance' test suite bug/feature list investigate how bugs happen

Important topics, continued disaster control –backup data stores –backup procedure security –hackers –insiders Note: security protections also help in benign situations: knowing where you need to look and where you don't need to look to uncover problems.

Reminder: Objects are information + procedures properties + methods attributes + operators information + behavior … can be defined by you, the programmer. DOM is the Document Object Model used for client side (for example, document.write( ) ). asp is essentially a set of objects (Request, Response, etc.) called the intrinsic objects. php support resembles other oo languages more than JavaScript (maybe more than VBScript?)

php example (partial) class node { var $mparent; var $mfirstchild; var $mnextsib; var $mname; var $mlocation; } function Node ($parent, $name, $location) { $this->mparent = $parent; $this->mname=$name; $this->mlocation=$location; } function addchild($child) { if isset($firstchild=$this->mfirstchild) { $firstchild.addsib($child) } else {$this->mfirstchild=$child;} } function addsib($sib) { } } ends class constructor method

php example … $newnode = new Node (&$current, 'curley', 'NYC'); invokes a call to the constructor function node, which sets up an instance of a node. … $current.addchild (&$newnode); this invokes the method of $current that will connect it to $newnode. Access object properties: … = $current.mlocation; see next

more php inheritance: –class specialcustomer extends customer { } overriding –re-use name of method reference operator (pointer) –$place = &$node; $place will refer to same thing, not a copy eval ($string); evaluates the contents of $string.

JavaScript OO support Limited, but can use functions in a var statement and can name a procedure as a property. –connects data and code Neither php nor JavaScript has information hiding mechanisms –This is not for keeping something secret as much as for catching an error during compilation that would otherwise lead to a logical, runtime error. no inheritance support –building objects from other objects to save redundant coding AND have the system apply the appropriate procedure.

JavaScript OO support: basic var node = new Object(); node.mname= "curley"; node.addchild=addchild; a function defined elsewhere

JavaScript example: using constructor function node (parent, name, location){ this.mparent = parent; this.mname = name; this.mlocation = location; this.addchild=addchild; this.addsib = addsib;} function addchild (child) { } function addsib (sib) { } this is term for thing being created.

JavaScript example: usage var person = new node (parent, 'moe','nyc'); parent.addchild(person); … = person.mlocation;

Benefits of oo Encapsulates information and treatment of information to make code either to maintain and to re-use –only one place to check and to modify if you need to change how you 'add a child' in the previous example. –catches errors as compilation (syntactic) errors.

Emerging technologies, infrastructure broadband wireless—smaller devices WAP, XML, XSL, XSLT, WML Application Service Providers new/not so new offerings: –Cold Fusion –asp.net, vb.net, Active X objects (for sale) –Open Source php

XML Building XML applications with Java –Large[r] applications requiring communication between components Creating User Interfaces –xml and xslt, also wml, VoiceXML

Questions for final quiz See guide to final quiz posted online. Note: final will be open book, open notes. You do need to study.

Projects Prepare to demonstrate and to show your storyboard diagram (and maybe the others diagrams as reminders). Prepare hardcopy of diagrams plus choice essay if you needed to do one. Send URL of project to me!