An Introduction to APR 2.0

Christian GrossConsultant

ChristianHGross@yahoo.ca

Montreal, Canada

Bio: Christian Gross

Author of several books Conference speaker Skills

– Specialization in Internet, and Infrastructure technologies

– Windows, UNIX, LINUX server development

Companies worked/consulted for– UBS, TATA, Grammer, National Westminster,

Daimler Chrysler, ETSI, ITU, Fame, NCR, etc

Agenda

Discuss what APR represents– Why APR– Main points of APR

Go through demos that illustrate the various concepts of APR

APR????

APR: Apache Portable Run-time Mission Statement

– The Apache Portable Run-time mission is to provide a library of routines that allows programmers to write a program once and be able to compile it anywhere

Yet another “Portable” Runtime?

Original choices were NSPR, ACE or another library

NSPR not used because of license issues and then too many features not required

ACE used C++, which is useless with Apache Finally wrote APR, which is a continuation of

ap_ work done in Apache 1.3.x

What APR does

Abstracts the OS into a series of Apache related functions – Simpler for porting Apache to other platforms– Solves the following problems

Threads Processes Directories

APR Core: contains fundamental portable functions

APR Util: contains functions that are not core, but need to be portable

Core APR

Contains following functionality– Reading and writing of files– Character set conversion– Network communications using sockets– Time management used for Internet type

conversions– String management like C++ including natural order

management– UNIX Password management routines– Table management routines

Core APR (cont.)

Contains following functionality (cont.)– UUID Internet generation– Filename canonicalization– Random data generation– Global lock management– Threads and process management – Dynamic library loading routines– Memory mapped and shared memory

Managing Data Structures

Cross platform is problematic because not all functionality is supported

Structures look like spaghettitypdef struct foo {

#ifdef WIN32

LONG item1;

DWORD item2;

#endif

LONG shared;

};

Do not want to give programmers direct access– Violates cross-platform

capabilities False sense of security

Incomplete Data Types

Solves problem of managing data structures across platforms

Data type is defined using a “handle” Data type is managed using a number of

routines– Programmer does not have direct access to

structure details

But not all of APR is incomplete data type based

APR Status Codes

Used to indicate when things work and do not work Different types of errors based on the sub-system that

causes the error– Operating system native function calling error– Function calling error

APR will provide error codes for OS’s that do not support the native error or maps error codes

– Errors codes provided by layered application– Success codes

Can include extra information indicating state

Examples

Demos illustrating the various concepts of APR– Available at www.devspace.com

Look for Apache APR Demo Code

Where to get APR?

APR is distributed with Apache 2.x Can get standalone version by going to http://

apr.apache.org There exists an APR mailing list at above

mentioned website– Documentation is currently sparse

Thanks!

Questions?(Send me email)