What are the differences between webservers?

Apache

As the maturest and most flexible of available webservers, functionality is first developed for Apache. In some cases functionality can be ported to other webservers, in other cases not - e.g missing support for chunked transfer encoding in Lighttpd means that Live ingest is not supported in Lighttpd.

The following sections document these differences as well as outlining what can be ported, focusing on Apache and Nginx.

Configuration

The list of available Apache All virtual host related options (keywords to be used in the virtual host configuration file) is the following:

Configuration key	Description
UspLicenseKey	The USP license key, the default is to place this in /etc/usp-license.key.
UspHandleIsm	Set to 'on' to enable mod_smooth_streaming functionality.
UspHandleF4f	Set to 'on' to enable mod_f4fhttp functionality.
IsmProxyPass	Pass .ism to proxy (a virtual path and URL).
UspIssPassThrough	Set to 'on' to pass through MP4 fragments directly to Smooth Streaming.
UspPreferStatic	Set to 'on' to prefer static files over dynamically generated files.
UspEnableMMAP	Set to 'off' to disable use of memory-mapping.
UspSkipRewrite	Set to 'off' to enable the internal rewrite rules. (NOTE: this was 'off' by default in 1.10.25 and earlier, but in 1.10.26 and later it is now 'on' instead).
UspDynamicTimeShiftBufferDepth	Set to 'on' to update the @timeShiftBufferDepth attribute dynamically.
UspOutputFilter	Filter output through an external command.x
UspForceContentLength	Set to 'on' to force determining Content-Length even for dynamic content.
S3SecretKey	The AWS secret key.
S3AccessKey	The AWS access key.
S3Region	The AWS region. Required for AWS Signature v4.
S3SecurityToken	The AWS security token, if required; see Temporary security credentials in IAM. (Added in 1.11.13)
S3UseHeaders	Set to 'on' to use HTTP headers for AWS authentication, instead of query parameters.

Further, in Apache it's possible to have Custom HTTP Status codes (Apache):

Apache only functionality

The following functionality is available only in Apache:

• Progressive download

• Download to own for HTTP Live Streaming (HLS)

• Unified Remix

The cause for this is how Apache structures resource management (RAM, file access etc).

Nginx

Configuration

The following configuration options are available:

Option	Description
usp_license_key	The USP license key, the default is to place this in /etc/usp-license.key.
usp_handle_ism	Enables mod_smooth_streaming functionality.
ism_proxy_pass	Pass .ism to proxy (a virtual path and URL).
usp_handle_f4f	Add to enable mod_f4fhttp functionality
usp_disable_mmap	Add to disable use of memory mapped I/O.
s3_secret_key	The AWS secret key.
s3_access_key	The AWS access key.
s3_region	The AWS region.

The status code mapping can be done with Lua in Nginx:

header_filter_by_lua "
    FMP4_FRAGMENT_MISSING = 404
    if ngx.status == FMP4_FRAGMENT_MISSING then
        ngx.status = 204
    end
";

Unavailable functionality

Due to how Nginx is structured internally, the following functionality is not available on Nginx:

• Progressive download

• Download to own

The use of ism_proxy_pass is limited in the sense that the reference may not be to Nginx itself. For background on this see What is the preferred webserver for media delivery?.

Lighttpd

For Lighttpd none of the options as listed for Apache are available.

Further, the following functionality is not available:

• progressive download

• download to own

• live ingest

IIS 5/6/7/8

For IIS none of the options as listed for Apache are available.

Further, the following functionality is not available:

• progressive download

• download to own

• live ingest (IIS 7/8)

Webserver Overview

The following table provides an overview of features available or not due to webserver internals:

Webserver	Progressive Download	Download to Own	Live ingest	Remix
Apache	y	y	y	y
Nginx	n	n	y	n
Lighttpd	n	n	n	n
IIS	n	n	n	n