The browser keeps track of the pages that have been navigated to in a history. SYS_WEB.history.add allows you to add the current URL to this history so the user can then go forward or backward between pages using the browser navigation.
This feature makes use of a concept called Deep Linking which can be interpreted as:
any link that directs a user past the home page of a website or app to content inside of it.
In LANSA this is the practice of using the query string portion of the URL to indicate a particular page or feature of a web application. For example, the following type of URL:
This will cause the browser to navigate to the domain (www.asite.com), and it is assumed that as part of the load that the query string portion of the URL will be interpreted and the site will show page 37 of the product list.
A given web page can only manipulate the history with reference to its own domain. Thus, it is not possible when on www.asite.com to add history entries for www.lansa.com. So, the Add method of the SYS_WEB.history object takes a string that will be appended to the current domain as the query string. When you use the forward and back buttons, this updates the browser URL replacing the query string information.
Deep links are particularly useful for sharing information as a link and can be used to open to a specific piece of content or action.