This Node's function is to provide persistent data storage and retrieval in support of the user to-online buying transactional interaction.
Customer related data that is stored is relevant to the specific business interaction, for example, the shopping cart and shipping address information. Some sites are registering users and storing customer profile data such as address, clothing sizes, preferences, and gift wish lists that others can access when buying presents. Most sites today do not store credit card information on this server for security reasons.
Also stored here is the product and catalog information used to dynamically build HTML pages for presentation during the shopping process.
The mode of DB access is perhaps the most important factor determining the performance of this Web application, in all but the simplest cases. The recommended approach is to collapse the DB accesses into a single or very few calls. This can be achieved using coding and invoking Stored Procedure Calls on the database. Typically many commerce servers share only one database server in a high volume site, so the technology to implement this node must be able to scale vertically.