The way to share session variables between two runs of an application is to persist the session variable by means of HTTP cookies. Genero must provide a way to set and get session variables to and from cookies.
Figure 1. Create, Set, and Get Session Variables and HTTP Cookies
A session variable or cookie can be created and updated in the following ways:
- From the GAS, an administrator can create and set HTTP Cookies in the configuration file.
- From the application, a 4GL developer can set or get session variables through front-end functions.
- From the templates (snippet-based rendering engine), a designer can prepare form variables with a snippet-based rendering engine function or CSF function and can access session variables through template paths.
- From the User Agent (browser), a request can set session variables through form variables. A session variable can be created using a Client Side Framework function.
Session Variable / HTTP Cookie synchronization
Every session variable may not need to be put into an HTTP cookie. Conversely, every HTTP cookie value need not be put into a session variable.
The idea is to tag each session variable that has to be set into a cookie. The snippet-based rendering engine (with the GAS) would be in charge of maintaining the cookies/session variables synchronization. On incoming HTTP requests, the engine would update corresponding session variables; on outgoing HTTP responses, the engine would set changed cookies. Between the request and the response, the 4GL developer can update session variables. Therefore, updating an HTTP cookie is indirectly done by updating its session variables.