Enterprise Software products are unique and generally different organizations use it differently. It will be rare or impossible to see enterprise software used without modifications by enterprises. A typical enterprise has unique needs based on their organization structure and they customize the software available off the shelf. They hire functional and technical consultants, who have expert level knowledge of underlying technology and functionality to perform these customizations. The nature of customization could be either simple UI change, data model change or it could even more complex such as behavioral change (i.e. configuring workflows, adding business rules etc.,) or third party integrations. The consultants will typically make changes to the application source code and would require source code maintenance with the enterprise.

With the emergence of SaaS delivery model and multi-tenancy needed to achieve economies of scale, software customization for individual is not a viable option. The vendor will not be able to maintain versions of software for every customer and with software available on cloud the enterprises cannot maintain source code in house. At the same time, customers should be able to extend the product functionality to suit their needs. Software extensibility framework helps software to be customization without a need to change the underlying source code. A good extensibility framework design will allow the end users to customize the software and these customization will be visible only in the instance which the customer is accessing.

An extensible design can be categorized as following.

• UI Extensibility: The user interface layer should be extensible and the customer should be able to customize the look and feel of the application. This customization can range from changing colors, application branding (i.e. changing logos), changing widgets look and feel and advanced customization such as customizing label texts, show/hide UI widgets, customizing error messages etc.,

• Data Model Extensibility: The end users should be able to extend the data model for any object. They should be able to add a new field to the form and add data to it. The field can be of any data type including the multimedia content. The application should allow for defining validation rules and lookup values. Note that the data model extensibility generally doesn’t allow for creating data model or re-defining object relationships.

• Workflow Extensibility: A typical business process consists of a workflow that is sequence of connected steps helps complete a task. The extensibility should allow the end users to configure these workflow steps (i.e. add/delete a step), define business rules, add notifications etc.,

I will discuss each of these with an example in my subsequent posts.