Integration Design Pattern – Synchronous Facade for Asynchronous Interaction by Shreenidhi Raghuram

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Introduction

In this blog, we will explore a Hybrid Message Interaction pattern, which combines the characteristics of traditional Synchronous Request-Reply and Asynchronous patterns. We will also see, the need for such a design pattern and how it can be implemented using Oracle SOA Suite.

Need for this Design Pattern

A Hybrid Synchronous-Asynchronous message exchange pattern is a requirement that pops up often in architectural discussions at customer engagements. The below discussion summarizes the need for such a design pattern.

Consider the following scenario:

A Web Client end-user fills in a form and submits a request. This is a blocking request and the client waits for a reply. The process is expected to reply to the user within a short period and let us assume that the client times out after 30 seconds. In a happy path, the backend systems are responsive and user receives the response within 30 seconds. This is shown in the below ‘Synchronous – Happy Path’ diagram.

Now, consider if a backend delay or system outage prevents a response from the website within 30s. All that the client receives is a Timeout Error. No further information is available and the user can only refill and resubmit the form, another time! This is shown in the below ‘Synchronous – Not so Happy Path’ diagram.

The above solution is designed for the happy path. It can even be optimized for a high throughput in the happy path scenario. But for the negative path, it is desirable to have a more responsive and user friendly behavior. We should note that any design for the negative scenario would inherently be Asynchronous in nature, as we do not want the user to wait for the delayed response. Rather the user should be notified by other means whenever such a response is available.

Even though the percentage of requests that end up in the delayed scenario may be quite less, it is still desirable that such requests are handled in a more user friendly manner. We also want to achieve the Asynchronous error handling without sacrificing the high performance of a purely synchronous interaction.

The next section proposes such a design. Read the complete article here.

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Technorati Tags: SOA Community,Oracle SOA,Oracle BPM,OPN,Jürgen Kress

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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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