Oracle Fusion Middleware customers use Oracle Service Bus (OSB) for virtualizing Service endpoints and implementing stateless service orchestrations. Behind the performance and speed of OSB, there are a couple of key design implementations that can affect application performance and behavior under heavy load. One of the heavily used feature in OSB is the Service Callout pipeline action for message enrichment and invoking multiple services as part of one single orchestration. Overuse of this feature, without understanding its internal implementation, can lead to serious problems.

This series will delve into OSB internals, the problem associated with usage of Service Callout under high loads, diagnosing it via thread dump and heap dump analysis using tools like ThreadLogic and OQL (Object Query Language) and resolving it.

The first section in the series will mainly cover the threading model used internally by OSB for implementing Route Vs. Service Callouts.

The second section of the "OSB, Service Callouts and OQL" blog posting will delve into thread dump analysis of OSB server and detecting threading issues relating to Service Callout and using Heap Dump and OQL to identify the related Proxies and Business services involved.

The final section of the series will focus on the corrective action to avoid Service Callout related OSB serer hangs. Before we dive into the solution, we need to briefly discus about Work Managers in WLS.

Please refer to the blog posting for more details.