Internals of CppCMS 1.x.x
The CppCMS framework consists of following parts:
Long Living Classes
Central
service— the major class that holds the main application loop and manages all resources.All global resources are accessed via this service.
It also hold the main event driven execution loop based on
boost::asio::io_service.applications_pool— it the class that holds a pool of user created applications and dispatches them according to requested url. It is the major connector between URL and application.Each time the page is requested an application fetched from it and then returned back for recycling.
thread_pool— is the thread pool for long running and time consuming jobs that can’t be executed withing asynchronous event loop.Generally, when new request arrives it is executed by application in the
thread_pool.locale::pool— is the gateway to i18n and l10n world. It holds the set ofstd::localefor each supported locale required by developer. It also adds custom facets likegettextin order to extend localization capabilities behind the strict set of facets provided by standard C++.The configuration of all CppCMS components is done via single JSON object that is loaded by
serviceand accessible viajson::object const &settings()member function ofserviceclass.
Connection Related Classes
When the main loop is started all incoming connections
are accepted and processed by impl::cgi::connection class.
This is an abstract class that various protocol connectors implement it. Currently CppCMS supports following protocols:
- HTTP — very simple and limited implementation of HTTP protocol that is used for debug purposes or for running CppCMS behind http-proxy.
- FastCGI — connector that implements standard FastCGI web server API and allows running CppCMS application behind any web server.
- SCGI — connector that implements standard simple and very useful SCGI protocol that is simpler equivalent of complex FastCGI.
So, each time new connection is accepted it is read completely, including parsing headers and all POST data.
When the connection becomes ready it is assigned
to user visible http::context object that provides
an interface for user to lower level CGI like protocol.
When the http::context is ready, appropriate application
is fetched from applications_pool and http::context
object is assigned to it.