Mbedthis Appweb supports extension modules that can augment the capability of Appweb by
adding new features, handlers or protocols. In fact, you can put into an Appweb modules almost
anything -- only limited by your imagination.
Appweb is itself comprised of 11 different modules. The core appweb HTTP server cannot serve
any pages or documents by itself. It relies on URL handlers delivered as modules to actually
serve HTTP requests. Other Appweb modules include SSL handling, a file upload capability and
authorization handling.
This document describes the Appweb Module Interface and how to create Appweb modules. The
Appweb Module interface supports both dynamicly loaded and statically linked modules from a
single C++ code base.
See also how to configure loadable modules and the
simpleModule sample for sample code implementing a
simple Module.
Overview
To create
an Appweb module, all you need to do is create an instance of a subclass of the
MaModule class. When instantiated, this class informs Appweb about your module and
makes it available for service.
If you want to statically link your module, you need to ensure the main program creates an
instance of the MaModule class during its initialization.
You can also, optionally, make your module dynamically loadable. To do this, your code must do
two more things:
- It must be packaged as a DLL / shared library
- The DLL must export a specific initialization function
The MaModule Class
You should subclass MaModule and create your own derived class so that you can optionally
implement the constructor, destructor, start, stop and parseConfig methods. These methods will
be invoked at various stages of the construction and initialization of your module.
The constructor will be called when your Module class is
instantiated and the destructor method will be called when it is
destroyed. The start method will be called when the Appweb server is
started in reponse to the start method of the MaServer being called.
The stop method is usually called only when Appweb is being shutdown.
The parseConfig method is called to allow your method to implement
custom parsing of the Appweb configuration file.
The class definition for an Appweb Module is described below. Note that all methods are
optional.
class MyMod : public MaModule {
public:
MyMod(void *handle);
~MyMod();
int parseConfig(char *key, char *value, MaServer *server,
MaHost *host, MaAuth *auth, MaDir* dir,
MaLocation *location);
int start();
void stop();
};
The start and parseConfig methods should return 0 if successful. Otherwise they should
return an MPR error code described in mpr.h. The parseConfig method is given a directive
key and it's value. Other parameters provide
context information for the directive.
Initialization Function
If your module is to be named MyMod, then you must create an initialization function of the name mprMyModInit. This function is used if you want your module to be a dynamically
loadable module.
extern "C" int mprMyModInit(void *handle)
{
new MyMod();
}
The extern "C" is necessary so that the function will be exported without the usual C++ name
mangling. You can put any initialization in the initialization function, although it is usual
to put most of this in the module contructor.
