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Developer Potpourri

About​

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.

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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.