IBM Enterprise Workload Manager Release 1

6 IBM Enterprise Workload Manager

managed server layer understands each of the supported operating systems, gathering

resource usage and delay statistics known to the operating system.

A second role of the managed server layer is to gather relevant transaction-related statistics

from middleware applications. The application middleware implementations, such as

WebSphere Application Server, understand when a piece of work starts and stops, and the

middleware understands when a piece of work has been routed to another server for

processing, for example, when a Web server routes a servlet request to a WebSphere

Application Server.

The managed server layer dynamically constructs a server-level view describing relationships

between transaction segments known by the applications with resource consumption data

known by the operating system. A summary of this information is periodically sent to the

domain manager, where the information is gathered together from all the servers in the

management domain to form a global view.

An important aspect of the EWLM approach is that all data collection and aggregation

activities are driven by a common service level policy, called the EWLM

Domain Policy. This

policy is built by an administrator to describe the various business processes that the domain

supports and the performance objectives for each process. For example, a book store would

probably have a business transaction called “Add to shopping cart” that would have a

performance goal of perhaps a 1.5 second response time.

To permit the EWLM domain manager to construct an end-to-end view of each type of

business transaction, the processing segments performed by each participating middleware

instance must be correlated, meaning pieced together. For example, the Add to shopping

cart transaction would be received by a Web server, it could flow to a WebSphere

Application Server instance which might update a database. The transaction might even

check your credit limit by routing a sub-transaction to another server. The tricky part of this

correlation is to get all of the applications in the path of each transaction to cooperate, without

knowing that they are cooperating.

The final aspect of EWLM to introduce is the EWLM

Control Center, a browser-based

application server tailored to the needs of an EWLM administrator, analyst, and operator. This

is where all the EWLM concepts come together; where you can create a service level

domain

policy

and activate that policy on hundreds of servers with a single click. Reporting data is

then available to let you view performance from a business perspective. And if you need the

details, you can see the topology of servers and applications supporting each transaction

type and understand where the time was spent.

The information is organized in such a way that an administrator or analyst can easily

drill-down to what is relevant.

1.2.1 Domain manager

The domain manager is a software stack that you install and configure for your EWLM

environment. It consists of two operating system processes: one supports the Control Center

and one coordinates policy across the managed servers and aggregates performance

statistics. The size of the server that you install the domain manager on is dependent on the

number of managed servers and the Domain Policy complexity. See “Initial performance

considerations” on page 219 for more details.

The domain manager has a complete view of what’s going on in the domain. It keeps recent

historical data collected from the managed servers. The data can be displayed for as little as

one minute or up to an hour interval.