In a more traditional service deployment, services are added to "the" web server--typically, Apache. Each service mingles with others in providing CGI executables or PHP files. The files are all commingled in the Apache file space, and a compromise of one gives access to all the file access rights of all the other installed functions (usually the user id "www-data").
This organization made sense when providing web services was a large and demanding task. With the growth of available power--measured in CPU, memory, bus bandwidth, or networking bandwidth--this need to share "the" web server across all services is greatly reduced. It is now quite reasonable to have any given service provide its own web interface through a simple library module. With this change of motivations, it thus becomes sensible to decouple services from each other.
My implementation can be found at: http://sources.vsta.org:7100/chore/index