With the advent of cloud, the trend is to use cloud-based best of breed software for different needs. Although this provides very good and deep functionality, it also opens up a lot of issues related to data management and integrity.

A very common scenario nowadays is to use SaaS application like Salesforce or SugarCRM for CRM. Then to use SaaS ERP like NetSuite or on-premise ERP. There could also be Quickbooks used for accounting. Besides these there are the HelpDesk apps.

All of these applications have their own internal databases, schemas and representation of your data. A change in one place needs to be reflected in other apps as well. This results in lot of difficulties on how to integrate the apps. Conventional star topology or app-to-app integration fall short.

This is where a Messaging Oriented Middleware (MOM) solution like ESB is very useful. I am presenting a generic architecture for multiple apps to apps integration.

Brief explanation of components in the proposed architecure –

• Purchase Order – This is the input document that comes to the system. We generally need to update multiple systems based on the docuemnt. The format could be cXML or any custom XML schema. It could be transformed into a standard or canonical format accepted internally.
• ActiveMQ JMS – The document is put on Topic of any messaging application. I have assumed ActiveMQ here, but it could be any MQ system that supports publish-subscribe model.
• Transformers – We have 3 subscribers to this Topic, however each of them accepts different formats. To compensate for this, we have a trasnfromer for each of the subscriber. e.g., the PO to CRM transformer could transform the message from CXML format to SalesForce.com Schema.
• Subscribers – All 3 subscribers receive the message document and update their respective system with the data.