Question

Discuss the differences, advantages, and disadvantage of data-centred and data-flow architectures. Give examples where either of these two styles would be applicable.

Answer 1

Data centred architectures:

• A data store will reside at the center of this architecture and is accessed frequently by the other components that update, add, delete or modify the data present within the store.
• The figure illustrates a typical data centered style. The client software access a central repository. Variation of this approach are used to transform the repository into a blackboard when data related to client or data of interest for the client change the notifications to client software.
• This data-centered architecture will promote integrability. This means that the existing components can be changed and new client components can be added to the architecture without the permission or concern of other clients.
• Data can be passed among clients using blackboard mechanism.

Some advantages of the data-centered architecture are listed below.

1. Clients operate independently of one another.
2. Data repository is independent of the clients.
3. It adds scalability (that is, new clients can be added easily).
4. It supports modifiability.
5. It achieves data integration in component-based development using blackboard.

Disadvantages of data centre architecture

• One-to-one communication with clients is reduced significantly
• Security related issues may crop up through increased dependence on the data center provider
• Need for additional efforts such as sudden cost expenditures, infrastructure creation, etc. may arise
• Responsibility and answerability are in disorder when due diligence is not practiced
• Challenges caused due to natural disasters are more common in this method of operation
• The general location of data centers is far away from premium network hubs, requiring more travel on behalf of the in-house executives

The most well-known examples of the data-centered architecture is a database architecture, in which the common database schema is created with data definition protocol – for example, a set of related tables with fields and data types in an RDBMS.

Another example of data-centered architectures is the web architecture which has a common data schema (i.e. meta-structure of the Web) and follows hypermedia data model and processes communicate through the use of shared web-based data services.

Client Software Client Client Software Software Client Client Data Software Software Store Client Client Software Software Client Software

Data flow architectures:

• This kind of architecture is used when input data to be transformed into output data through a series of computational manipulative components.
• The figure represents pipe-and-filter architecture since it uses both pipe and filter and it has a set of components called filters connected by pipes.
• Pipes are used to transmit data from one component to the next.
• Each filter will work independently and is designed to take data input of a certain form and produces data output to the next filter of a specified form. The filters don’t require any knowledge of the working of neighboring filters.
• If the data flow degenerates into a single line of transforms, then it is termed as batch sequential. This structure accepts the batch of data and then applies a series of sequential components to transform it.

• Most of the times, the data-flow architecture degenerates a batch sequential system. In this system, a batch of data is accepted as input and then a series of sequential filters are applied to transform this data. One common example of this architecture is UNIX shell programs. In these programs, UNIX processes act as filters and the file system through which UNIX processes interact, act as pipes. Other well-known examples of this architecture are compilers, signal processing systems, parallel programming, functional programming, and distributed systems. Some advantages associated with the data-flow architecture are listed below.

1. It supports reusability.
2. It is maintainable and modifiable.
3. It supports concurrent execution.
4. Some disadvantages associated with the data-flow architecture are listed below.
5. It often degenerates to batch sequential system.
6. It does not provide enough support for applications requires user interaction.
7. It is difficult to synchronize two different but related streams.

Disadvantages of data flow diagram:

• It make the programmers little confusing concerning the system.
• The biggest drawback of the DFD is that it simply takes a long time to create, so long that the analyst may not receive support from management to complete it.
• Physical considerations are left out.

It is suitable for applications that involve a well-defined series of independent data transformations or computations on orderly defined input and output such as compilers and business data processing applications.

Filter Filter Pipes Filter Filter Filter Filter Filter Filter Filter Filter