IBM Enterprise Workload Manager Release 1

Chapter 7. Using load balancing 193

7.4.2 Application-level identification

The flow illustrated in Figure 7-3 shows the mechanism for application-level identification. The

application-identification mechanism organizes similar data by the corresponding application

criteria registered by the load balancer.

Figure 7-3 Application-level identification

1. The load balancer registers IP address, port and protocol representing applications with

the domain manager.

2. The domain manager determines if it knows we are already looking for statistics for this

application. If the domain manager doesn’t know, the server ID of the system the

application is running on will be obtained from the information that was sent from the

previous system-level identification. The server ID identifies which managed server to

send the message to in step 3. If the result of this check reveals that no corresponding

server is registered, the contact flag for this instance is set to NO_CONTACT. When

seeking new information to calculate the next iteration of weights, the domain manager will

attempt to resolve this instance again.

3. The domain manager sends a message to the managed server with the port and protocol

of the applications we want application-level statistics from.

4. The managed server takes the port and protocol we want to resolve and sets a particular

PID. Now, the managed server will not only periodically determine all the IP addresses

associated with the machine (as described in the “System-level identification” on

page 192), it will also get the PIDs associated with previously set ports and protocols.

5. All IP addresses and IP/port/protocol combinations with their corresponding PIDs (if they

have been determined) for the interested applications are periodically sent to the domain

manager.

6. Structures are created in the domain manager to associate IP, port, and protocol to the

application’s corresponding statistics.

7. Periodically, the statistics are retrieved containing the load balancer-registered instance

identification and the weights calculated.

Note: All applications we are interested in tracking on the receiving system are included

in this message. It will replace the list kept in the managed server.

Domain Manager Managed Server

4. MS resolves IP port

and protocol to a PID

(application).

7. Weights calculated

based on statistics

3. DM sends a message

to MS with IP port and

protocol of app to obtain

statistics.

2. Check if MS & DM

already know we are

looking for statistics for

this application?

1. Load Balancer

registers IP address,

port and protocol

5. Add IP address and

PIDS to the message to

send to the DM

6. Associated structures

created