2.4 How Does It Work?

So how does it work? To be specific, let's consider accessing the service by sending the text message "example something red" to the phone number DOTCOM (368266).

First, the system uses the first word of the query "example" and the phone number DOTCOM (368266) through which the query is received to determine that the query should be routed to example.com. Next, the system retrieves the file index.cmrl from example.com. Next, the system compares the remainder of the query (i.e. everything after "example," which in this case is the string "something red") against the match patterns specified in the file index.cmrl in order to resolve the query. In this case, there is only one match pattern specified in the file index.cmrl--the match pattern "something"--which is matched by the first token "something" of the string "something red" and which resolves to the <engine> tag. Next, the system calls the engine "something.cgi" referenced by the <engine> tag, posting the remainder of the query (i.e. everything after "something," which in this case is the string "red") to the engine as the parameter "sys_argument." The engine uses the value of the parameter "sys_argument," which it assigns to the variable "$color," to construct the response, which it assigns to the variable "$content." Finally, the engine prints the value of the variable "$content" within a CMRL <message> tag, which produces the message "Apples are red" (or similar) returned by the system.