These diagrams illustrate something called the three-layer

These diagrams illustrate something called the three-layer or three-tier architecture. Systems architecture is a kind of 30,000 foot view of your system. It shows what the major pieces of the system are and how they communicate. The three-layer architecture is a very common solution to the need for architecture for a software application. Each layer is implemented on one or more computers. The most common example is a Web Application. The View Layer is all the browsers that are sending requests to the web site. The View Layer is responsible for displaying the information the application computes. It knows nothing about the business rules that were used to compute the information it displays. Neither does it know how the application it is a part of stores its data. The Domain Layer is implemented as an Application Server or Web Server that contains the business rules that defines how data is processed into information. It contains no knowledge of exactly how data or information will be displayed to the user. Nor does it have any idea how the data is stored. The Data Layer is responsible for persisting any data that needs to be saved. It is often implemented as a Relational Database engine (Oracle, MySQL, etc.). It knows the database schema and how to Create, Read, Update and Delete data. It knows nothing of the business rules that process the data into information or how the data/information is displayed to the user.

This separation of concerns has some software engineering benefits. It helps reduce errors (bugs) as software is upgraded. Each layer is responsible for doing only one kind of thing so that reduces the complexity of the code at each layer.

This separation of a software application into layers also requires some sort of interface or communication protocol so the layers can communicate with each other. For our Web Application example the application protocol normally used between the View Layer and the Domain Layer is XHTML. The protocol normally used between the Domain Layer and the Data Layer is ODBC or a related database protocol.

1. Are the protocols mentioned above proprietary (owned by a particular for profit company) or are they an industry standard (regulated by a standards organization but available to anyone to implement)?

2. Whichever is the case in question 1, what is the advantage of the protocols being proprietary or industry standard (whichever you claim they are)?