Active DnA
From Active Software

Active Software's Dynamic n-tiered Architecture (DnA) is a middleware technology that aggregates many networked computers and makes them look, work and act like a single virtual CPU. The Active DnA provides a brokering service for COM objects that manages these objects and the client requests for them, providing five key enterprise-class benefits over standard Microsoft DCOM.

Active DnA (Dynamic n-tiered Architecture) is clever middleware that manages COM objects executing on an NT server farm. The DnA provides 5 key enterprise-class benefits over standard DCOM:

• dynamic load balancing,
• object pooling,
• fault tolerance,
• location abstraction and
• centralized object management.

The Active DnA: Building Blocks for Distributed Computing
With Active Software's Dynamic n-tiered Architecture (DnA), deploying components on an NT server farm just got a whole lot easier. The DnA is a simple set of building blocks for developing and delivering distributed object applications.

The DnA provides the developer with five main benefits:

• Fault Tolerance
• Load leveling
• Object Persistence
• Location Abstraction
• Component Management

The DnA is a set of COM objects and applications that harness the aggregate processing capacity of a server farm. This is accomplished by abstracting the network of individual DnA participants as a single "virtual computer" with almost mainframe-like power. This virtual computer is easily programmed using simple, standards-compliant, COM object calling methods. With the DnA, you don't program a computer, you program a server farm.

The key building blocks of the Active DnA are:

The Active Broker
The Active Broker is best described as a routing service. All client requests for COM interfaces are routed through the Broker. The Broker checks to see if the COM object is available on the DnA. If an interface is available, the Broker passes it to the client who invokes the object using the returned COM interface.
If the interface is not available, the Broker instructs an Agent to start a new instance of the requested COM object. The new instance is started on the DnA participant that currently has the lightest DnA load. This "grow as needed" capability provides the DnA with both natural load leveling and incredible scalability.

The Active Client
The Active Client is a COM object that provides communication services to the Active Broker. Programs that access the processing power of the virtual computer do so through the Active Client. The Active Client makes public the three simple methods necessary "program the server farm":

• InitClient(): The InitClient() method establishes a client connection to the DnA.
• QueryDnAInterface(): This method is used instead of the standard COM method, QueryInterface(). The QueryDnAInterface() method returns the COM interface of the requested COM object. This invoked COM object is executed on the server farm, however, instead of on the client workstation.
• FreeDnAInterface(): The DnA provides object pooling. This significantly improves application performance and, through its natural load leveling, provides for incredible scalability. To be a good DnA "citizen", developers call the FreeDnAInterface() method to free an object when they are through with it. Such good practice avoids the brokering of unnecessary duplicate COM objects.

The Active Management Console
The Active Management Console is used to "run the DnA". Server farm CPUs participating in the DnA may be managed as if they were one big PC. Components and business objects executing on the DnA may be deployed and updated from a single central console. The DnA may be started, stopped and dynamically expanded using simple administrator wizards. There is built-in performance monitoring and alert logging.
In short, the Active Management Console provides a single image view of the server farm. No site administrator should be without one!

Active DnA is a non-returnable product.