Everything you Should Know about the API Platform Groovy Policy by Ricardo Ferreira

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Introduction

Developers using the API Platform Cloud Service often make use of the built-in policies that comes with the platform; to implement any logic that needs to be executed before delivering the actual message to the backend service. One common policy used is the Groovy policy, which allows API developers to write Groovy scripts that can be executed either within the request or the response pipeline. These scripts can be used to inspect and even modify the message content (payload, queries, headers) therefore a very powerful tool to have at their disposal.

Because Groovy is a programming language, there are no boundaries of what can be implemented other than what is supported by its specification. Moreover; Groovy will accept any code that is valid in Java, bringing even more powerfulness to your APIs. However, this power comes with a high price to be paid.

The biggest challenge with the Groovy policy is that you have no way to verify if the code written is correct until it is deployed into the gateways. During deployment; the Groovy script will be transformed into a Java class that uses the code written as part of its implementation. If something in the script is wrong, there will be compilation errors that will cause the deployment of the API to fail, as shown in Figure 1.

This whole situation can be quite frustrating if complex Groovy code is being used or if one API accesses multiple instances of the Groovy policy, each one carrying different scripts. Hours can be spent trying to troubleshoot the root-cause of the deployment issue, which is a situation that the Oracle A-Team has been experiencing quite often with different customers. Thus, this blog will discuss the most important details about the Groovy policy, its common pitfalls and which situations must be avoided to ensure a smooth API deployment.

The Basics: Groovy Policy Under-the-Hood

Given the simplicity of the Groovy policy UI, you may be thinking that its internal implementation is also quite simplistic. After all, how complex should be getting a script that contains Groovy code and executing it in a JVM right? the truth is that it is way more complex than what may appear, and properly understanding what happens under-the-hood may give you a better perspective about what to expect from this policy. Read the complete article here.

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About Jürgen Kress
As a middleware expert Jürgen works at Oracle EMEA Alliances and Channels, responsible for Oracle’s EMEA Fusion Middleware partner business. He is the founder of the Oracle SOA & BPM and the WebLogic Partner Communities and the global Oracle Partner Advisory Councils. With more than 5000 members from all over the world the Middleware Partner Community is the most successful and active community at Oracle. Jürgen manages the community with monthly newsletters, webcasts and conferences. He hosts his annual Fusion Middleware Partner Community Forums and the Fusion Middleware Summer Camps, where more than 200 partners get product updates, roadmap insights and hands-on trainings. Supplemented by many web 2.0 tools like twitter, discussion forums, online communities, blogs and wikis. For the SOA & Cloud Symposium by Thomas Erl, Jürgen is a member of the steering board. He is also a frequent speaker at conferences like the SOA & BPM Integration Days, JAX, UKOUG, OUGN, or OOP.

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