As discussed in earlier sections, JavaScript applications have portions that run on the client and on the server. In addition, many JavaScript applications use the LiveWire Database Service to connect the application to a relational database.
Clients can be inside or outside the corporate firewall.
It contains the application logic, manages security, and controls access to the application by multiple users, using server-side JavaScript. This tier allows clients both inside and outside the firewall to access the application. The WWW server also acts as a client to any installed database servers. It contains all the database data, metadata, and referential integrity rules required by the application. This tier typically is inside the corporate firewall and can provide a layer of security in addition to that provided by the WWW server.