"Hook" functions are functions you write to inject custom behavior at specific points in Jarvis's execution. You then assign the name of the function to the appropriate "hook". Hook functions can be located in #.CodeLocation - Jarvis will exclude them from being considered as endpoint functions. By default, no hook functions are defined; you need to define only the hook functions, if any, that are needed for your web service.
AppCloseFn
Description
AppCloseFn is the name of the niladic, function to be called when Jarvis is stopped. This function could do things like closing database connections, managing log files, etc. The function may return a 2-element array of (rc msg) where rc is an integer return code (0 means "okay") and msg is a character vector message. If the function does not return a result, the Jarvis will return the return code and message that was set prior to calling AppCloseFn.
Default
''
Examples
j.AppCloseFn←'ShutDown'
AppInitFn
Description
AppInitFn is the name of the monadic, result-returning function to be called when Jarvis is started. This function is called before Jarvis starts listening for requests. This function could do things like establishing database connections or other application initialization. The function should return a 2-element array of (rc msg) where rc is an integer return code (0 means "okay") and msg is a character vector message. If the function is monadic, its right argument is a reference to the Jarvis instance.
Default
''
Examples
j.AppInitFn←'Startup'
Notes
If your function returns a non-0 return code, Jarvis will exit.
AuthenticateFn
Description
AuthenticateFn is the name of monadic, result-returning function to be called when you need to authenticate a request. The right argument to the function is the Request instance. The function result should either be:
0 - meaning that authentication was successful or that no authentication was necessary for this request
1 = meaning that authentication failed in which case Jarvis will fail the request with an HTTP status code of 401 (Unauthorized).
Default
''
Examples
j.AuthenticateFn←'Authenticate'
Notes
See Authentication for more information about how to authenticate an HTTP request.
SessionInitFn
Description
SessionInitFn is the name of a monadic, result-returning function that can perform session initialization if your web service is using sessions. The right argument is the Request instance, which we'll call req. The reference to the session namespace is req.Session. The integer function result should be either:
0 - indicating that the session was successfully initialized
non-0 - indicating session initialization failed; in which case Jarvis will fail the request with an HTTP status code of 500 ().
ValidateRequestFn is the name of a monadic, result-returning function that will be called for every request that Jarvis receives. ValidateRequestFn gives you the opportunity to perform additional validation on a request. The right argument is the Request instance. The function result should either be:
0 - meaning that validation was successful or that no validation was necessary for this request
1 = meaning that validation failed in which case Jarvis will fail the request with an HTTP status code of 400 (Bad Request).