Informatica thrives on HA (High Availability) & SOA (Service Oriented Architecture). The central idea of Informatica architecture is the resilience to failure & load balancing. Keeping this in mind Informatica scales its operation amongst nodes created in a domain. Domain is simply a collection of nodes whereas Nodes are your physical machines performing operation. Domain information is typically stored in a database. Once a domain is in place you need to create a Master gateway node. Without a Master gateway node no entry point exists in domain and you can not use the domain conversely no Informatica operations can be performed since you can not access worker nodes.
How to distinguish between an ordinary worker node and a gateway node? Simply by the way it is configured. A node can be set as Gateway in Domain configuration section Log and Gateway Configuration.
Let’s stop here and discuss more about Node. As I mention they are nothing more than physical machines. They are logically represented in Informatica domain as Nodes. When I add any node in Informatica domain I have to configure its Name, Host & port at which the Informatica Service Manager is listening. Wait a minute …. a what manager?
Service Manager – It manages domain related operations as well as application services. This service manager runs as a Windows service or daemon on Unix. Service Manager has to be present on each node otherwise Nodes will not work. A service manager performs domain related functions & application services. What kind of domain functions? Well that varies from node to node. A gateway node will have authentication, logging etc performed by Service Manager whereas simply logging on a worker node as a part of domain functions. Apart from this the Service Manager also initiates the application specific services.
Once a node is having a service manager and that means Informatica Services, then that node can perform all gateway operations as well as application specific operations. Application specific operations are your Repository Services, Integration Services etc.
So you have
Domain -> Node -> Gateway or Worker or Both
Hope this helps you to give an idea of Informatica architecture. Do read the manuals for more details. Apart from that fire up your administration console and study the various sections/configurations in there.
BI Quest [A blog on Informatica] 