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Concepts
Modules
All modules are not equal. Most modules provide some simple functionality, while others provide complex functionality that have security implications. The Administrator has to take this into account before deploying such modules. This manual contains warnings about modules that have security implications, and a Security chapter that all Administrators should read thoroughly.
Virtual Filesystem
One special property of Challenger's virtual filesystem is that several modules may be mounted on overloading mount points. If one module is mounted on /foo/ and another on /foo/bar/ both modules are configured to handle a request to http://my.site/foo/bar/req?17. The priority of the modules determines which module will be used. In case the first module cannot handle the request it will be passed on to the second module. Overloading filesystems makes it possible to configure Challenger so that what is seen on the web can appear very different from how it appears on the filesystem. What appears as a single directory on the web might in reality be the union of several directories and databases.
Protocols
HTTP stands for Hyper Text Transfer Protocol and is the simple protocol used by web servers. HTTPS is HTTP over SSL, the Secure Socket Layer. It is in like HTTP, but also supports encryption, thus making it impossible to eavesdrop on the communication. Encryption is necessary for transfering sensitive data over the Internet. Apart from HTTP and HTTPS, Challenger also handles FTP, the File Transfer Protocol, an older protocol that was popular before HTTP. FTP is still in use today for downloading programs and uploading content to web sites. FTP is better suited for such tasks. As far as Challenger is concerned, there is essentially no difference between a HTTP request and a FTP request, so any feature available through HTTP is also available through FTP. This makes it quite possible, for instance, to create a database driven dynamic FTP site. |