The application created in this example is deliberately somewhat simplistic. The example is based on the assumption that no requirements specification was produced by the user and that the application creator, since he did not understand the user's business, did not appreciate the inadequacy of the user's brief verbal specification. Such a scenario is common enough in the computer industry.

Although the ERROS Application Creation System will normally be used to create applications that are considerably more complex than the one shown in this example, the same simple principles are used to create all ERROS applications. However complex the application, it can be created incrementally in small simple steps, just like the ones in this example.

There are two parts to the application creation process - defining the changes to the ERROS business model and then creating an ERROS application that acts as a filter to the ERROS business model.

The application must then be authorised and then tested.

No phsyical database design is required and no new AS/400 files or tables will be created. All data and application definitions and user data will be stored in the existing AS/400 physical files. No programs will be created, generated or changed for this application.

The whole process of defining the data, creating the application, authorising it and testing it can be completed in under 4 minutes by an experienced ERROS operator on a locally attached terminal. An operator with no previous experience of operating ERROS should complete the task in about 30 to 40 minutes.

The screen dumps shown in this example were taken by saving the source HTML for each screen when creating the application.

Developers using ERROS, even though they may not have any understanding of Object-Oriented technology, automatically create fully Object-Oriented applications with all their benefits such as re-use of definitions, multiple inheritance, etc..

ERROS applications are robust and able to handle large transaction volumes from multiple concurrent users. All data and application definition and user data database changes are journalled and an ERROS audit trail records who made each change, and when.

This application creation example illustrates the basic principles of creating ERROS applications. It shows how to create a new user defined entity type, how to re-use an existing ERROS defined attribute with the new entity type, and how to create new user defined attributes and apply them to both an existing ERROS defined entity type, and to a user defined entity type. It also shows how to define a relationship between two entity types. These steps are all part of the business modelling process and undertaken using the ERROS Business Modeller.

The example then shows how, using the ERROS Application Creator, the actual application is created. The example shows how to define the entity types to be used within the application, and how to create menus for those entity types. It also shows how to create an initial menu for the application. Fast path menus that allow operators to access any record with one command are automatically created, and the example also shows how operators can create synonyms for fast path menu entries to allow multiple fast paths to entity types.

The verbal specification received from the end user stated simply -

I am expanding my business and going into Video tape rental. Any existing contact might be a video shop customer. Customers will present an identifying card with their number on and each video will have a number. We need to be able to access people and tapes by name or number. I do not need an accounting system as no invoices will be produced. Customers will simply be given a till receipt. What I need is a simple system that can keep a record of my customers, their telephone numbers and the videos they currently have on rental.

Click here to see how to start up ERROS after you have signed on.

Click here to see how the extensions to the Business Model are made using the ERROS Business Modeller.

Click here to see how the application is built using the ERROS Application Creator.

Click here to see how the application that you have created is authorised using the ERROS Authority Organiser.

Click here to see how you can now test the application that you have created.