An Introduction to APR 2.0 Christian Gross Consultant 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 spaghetti typdef 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 Look for Apache APR Demo Code

Where to get APR? APR is distributed with Apache 2.x Can get standalone version by going to There exists an APR mailing list at above mentioned website – Documentation is currently sparse

Thanks! Questions? (Send me )