From left to right, the diagram shows software components called connectors; an application server divided into notification and interaction engines; two kinds of multimobile services; and a PC that represents the client software and SDK used to create these services.
The connectors in the diagram communicate with the various kinds of servers and services that are able to receive and respond to messages and requests from mobile phones. These include interactive voice response units (IVRs), SMS servers and/or services, IM servers, email servers, and web application servers. Connectors are like the software drivers that enable PCs to communicate with various kinds of peripheral hardware.
The notication engines sends one-way messages (notifications) to users who have subscribed to receive them. Notifications are scheduled to be sent at specific times. The notification engine, always running, retrieves them from the database in which they are stored and sends them to subscribers in the way they have elected to receive them - as text messages, as instant messages, as email messages, etc. - "multimobile" notifications.
The interaction engine receives messages from mobile phone users - mediated through the connectors - routes them to the appropriate interactive service for processing, and returns the response to the connector, which forwards it to the user. It is the combination of the connectors with the interaction engine that enables users to interact with the services in the way they prefer - by texting, IMing, emailing, calling, or browsing - "multimobile" interaction.
The PC on the right-hand side of the diagram represents two ways in which both notification and interactive services may be created. A software client called Reverie enables non-technical users to create relatively simple services, and a software development kit called Chimera enables programmers to create more complex custom services.
Not shown in the diagram is a prefabricated, customizable web site called Caprice. Caprice is a hugely important component of the system, providing services that enable several of the conditions enumerated in the Rationale to be met.
As you'll see in the tutorials, Reverie, Chimera, and Caprice (or their equivalents) are vital to the successful use of multimobile services. That it possible to use multimobile services at all, however, is due to Whimsy, the underlying infrastructure.