XML Information Modeling – An information model is a description of the information used in an organization .it is specific the meaning of data. In the absence of an information model, there is only data and no information.
In XML, an information model is used to understand the structure and meaning of the information that will be stored in XML documents. Information modeling help you identify the object involved in an application, the properties of the objects, and the relationship among them .The component of the XML documents can be easily identify after you create the information model.
XML provides the following additional capabilities to information modeling:
- Heterogeneity: Each record can contain different data fields. This can be used to express information, as it exists, without restrictions.
- Extensibility: New data type can be added whenever required. This allows you to accept, rather than avoid change.
- Flexibility: Data fields can vary in size and configuration between instance.XML imposes no restrictions on data.
You can create static, dynamic, or a combination of both these information models for an XML application.
XML Static Model
A static information model helps you to define all the objects in an application and the relationship among them. For Example, customer and account types can be two objects in an XML based banking application. The properties of customer object can be customer name, address, and account number, and the properties of account type can be saving account or current account. The type of account that a customer holds defines the relationship between the customer and account type objects.
Defining the XML Static Information Model
The best approach to define a static information model is step-by-step method. This method is described as follows:
- Naming: You should start the information modeling exercise by naming the various entities, objects, classes, and data elements.
- Defining the objects type: You need to define the objects types. For example, you need to define them “holiday” , to ensure that you can clearly recognize a “holiday”.
- Using the type hierarchy: You need to organize the listed and named object types into a hierarchical classification schema.
- Finding relationships: After heaving named the object types, the next stage in static information modeling is to determine relationship that exists among them.
- Defining properties: Properties are values associated with the objects. You need to define the properties of the objects.
XML Dynamic Model
In a XML Dynamic model, data flow diagrams and process diagrams are used to determine the flow of information. In this model, you determine the information flow of an application in the form of message. For example, a customer calls the front desk of a bank to get the address changed. The call-
center that handles the customer’s bank account. The call center executive accesses the customer information, verifies it, and then modifies the address. The modified information is then reflected in all future transactions for that customer.
Using the XML dynamic information model
If you are going to use XML for representing the message that flow around the system, you also need to understand what happens to data, where it comes from, and where it goes. Some of approaches for using dynamic information model are:
- Process and workflow models: These models focus on the roles of people and organizations in getting work done. The information stores and processing stages play a secondary role in these models.
- Data flow models: These models are similar to process and workflow models. They focus more on the information system instead of the business. A data flow model describes the following:
- Data stores that store the information
- Processors that manipulate the data
- Data flows that transfer data from one processor to another
- Object Models: These models have a dynamic component, as well as, a static component. The dynamic or behavioral part of an object definition concentrates on describing what each object can do, as a set of operations or methods that define its action.
- Object life histories: They focus on individual objects. Object life histories also describe what happens to each object throughout its lifetime, such as how the objects gets created, what events happen to it during its lifetime, what the object does in reaction to these events, and what condition cause the object to eventually be destroyed.
- Use cases: They analyze how specific user tasks are accomplished. Use case can be useful both in modeling the business and in describing the internal behavior of the IT system. Although a use cause can be similar to a process model, it generally focuses on the activities of one particular user.
- Object interaction model: These diagrams analyze the exchange of messages between objects at a finer level of detail than the data flow model. The data flow model might only identify that the online booking system sends transaction information to the credit card and gets authorization in response. In contrast, the interaction diagram will describe all the messages that make up this conversation in finer details.