ABSTRACT
This chapter introduces important PHP language constructs such as function definitions, reference parameters, passing function names as arguments, I/O and networking, and object-oriented programming in PHP. Authentication involves checking client supplied userid and password against stored data on the server side. The Hypertext Transfer Protocol (HTTP) protocol provides two ways for the Web server and browser to cooperate in performing access authentication: Basic Authentication and Digest Authentication. To authenticate is to check and verify the identity of the incoming person/program. The HTTP Basic Authentication does not provide a way to log out from a realm. Once a Web client caches the credentials for that realm, it continues to send credentials automatically upon each access to a resource in the realm folder. When a PHP-containing page is being loaded by the server, syntax errors may occur. To arrange for access protection, a server administrator simply needs to add access restrictions for the target files or folders in the Web server configuration files.
