Developer Potpourri

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There are lots of tidbits that don't easily fall into a specific category for developers, so here are some miscellaneous and somewhat random tips that have been gleaned from conversations with the FreeSWITCH™ authors.

Apache Portable Runtime

Informational Tip

Be sure to familiarize yourself with the Apache Portable Runtime (APR) - it contains lots of handy functions, data types, objects, etc. that make FreeSWITCH™ development a bit easier and more consistent across platforms. To prevent namespace collisions, apr_ objects have been mapped to the switch_ namespace. Please use the switch_ versions of apr_ objects. (Note: there is an exception to this - libmrcp). Examples:

switch_file_open in place of apr_file_open
switch_file_read in place of apr_file_read
switch_file_write in place of apr_file_write
switch_file_close in place of apr_file_close

You get the idea. See switch_apr.c for LOTS of great detail.


Channel Data

Informational Tip

When writing your own application within FreeSWITCH™ you can use switch_channel_set_private to create a hash in which you can put data specific to your own application. Example:

switch_channel_set_private(channel, "mydata", some_pointer_to_my_data);
some_pointer_to_my_data = switch_channel_get_private(channel, "mydata");


Debug Printing

Informational Tip

When debug printing, consider using alternatives to raw printf() calls. Raw printf() calls require a STDOUT which is not always available, i.e. when running as a service under Windows or under certain circumstances when running as a daemon under Linux/Unix. Better options are available:

switch_log_printf() - the most generic way to print a debug message. Allows for debug levels and printing messages to disk files, remote apps, etc. See here and here for more information.
stream->write_function() - more memory efficient; this avoids a malloc() call and therefore has a lesser impact on program performance. See here for more information.


See Also: Authoring Freeswitch Modules