2. NEED OF AN HOUR :
An application portfolio of a business organization is a compilation of information
about the organization's investments in its IT-based application infrastructure. The
information is organised to show how these investments support the organization's
mission and programs and to demonstrate the relationships among current and planned
investments.
The approach has its origin to 1996 Washington State Strategic Plan and includes the
foundational policies, procedures, and processes necessary to make informed
decisions about IT alternatives and achieve a very high rate of project success.
3. The application portfolio:
Discloses links among organization strategies and business plans and
investments in applications;
Facilitates analysis of the risks associated with investments made in
applications and helps ensure that appropriate risk mitigation strategies are
adopted;
Provides a baseline for organization-level performance reporting; and
Helps ensure that the organization IT infrastructure as a whole is effectively
integrated.
4. Portfolio-based application management is a coordinated approach to the stewardship of
the full range of technology investments. It ensures that new initiatives are seen both in
the context of the organization wide infrastructure and the respective department-specific
application portfolios.
It establishes a framework within which:
• Comprehensive information about the context of an organization's overall operations is
readily available for decision-making.
• The development and deployment of application is driven by the clearly defined
business needs of an organization in serving citizens and fulfilling its legislative
mandate.
5. • Department heads bring executive focus to application investments
and will have new management tools for meeting statutory
responsibilities for the stewardship of these investments in their
respective departments.
• A formal, objective process exists to evaluate whether a project
should be initiated and by which to determine the most appropriate
form of oversight based on a comprehensive risk analysis.
• Large projects are broken into smaller, more easily managed
projects with each phase adding value on its own without committing
funding authorities to subsequent phases.
6. TYPES OF FILES : DATABASES
• Depending upon the type of content ,a file can be categorized
as :
• 1. Data file
• 2. Program file
• 3. Object code file
• 4. Executable file System and Data Base
• 5. Text file (unformatted file)
• 6. Formatted file
7. Data files :
A data file is used to store the data records. These data files
are well defined data structures that contain related data
organized in convenient groupings (records) of data items.
l Each data file has two additional types of records: Header
record, and types record.
l Header records contain file identification information and
keep apart different groups of records in a file.
l Trailer records contain codes to mark the end of a set of
data records. These also record file usage information.
8. Depending upon the nature of data, data files can be categorized as:
1. Master file
2. Transaction file
3. Work file
4. Audit file
5. Backup file
File organization:
Data in files can be organized in different ways. These data records can be
organized in anyone of the following ways:
1. Serial
2. Sequential
3. Indexed Sequential
4. Directly Accessible/Random
9. Program Files
Program files are used to store programs in different languages provided by different software vendors. These
files have different extensions depending on the language used to write a program.
e.g.: 1. A program file written in 'C' language has extension. C.
2. A program file written is C++ language has extension. CPP.
Object Code Files
These files store compiled programs written in a language. These files contain the machine code.
e.g.: After compilation, C compiler creates a file having extension.OBJ
Executable Files
These files store ready to execute programs. These files may have extension.EXE.COM or .BAT.
These programs can be directly executed from the command prompt.
Unformatted Text Files
l These files are simple files containing simple text.
l Text files can be created using any text editor or line editor.
10. e.g.: Text files can be created using MS-DOS Edit editor or Notepad editor
provided by MS-Windows.
Formatted Text Files
These files contain formatted text. These also contain some commands and
symbols to format the text. These files can be created using any word
processor.
e.g. MS-WORD creates a formatted text file having extension .DOC
11. FILES ORGANIZATION
File organization refers to the relationship of the key of the record to the physical
location of that record in the computer file.
The two main objectives of computer based file organization are:
> ease of file creation and maintenance, and
> providing an efficient means of storing and retrieving information.
12. The four file organization methods that are commonly used in
business data processing
applications are:
1. Serial
2. Sequential
3. Direct or Random
4. Indexed Sequential
The selection of a particular file organization depends upon
factors like, the type of application, the method of processing
for updating files, size of file, etc.
13. Serial File Organization
In serial file organization records are stored without any
consideration of their order or sequence.
Records have to be accessed in the serial fashion only.
Examples are: memory dumps, archival files, records of events,
transaction files.
Each record is written after the last record in the current file.
The order of records in the serial file
is according to the time when the data was generated.
14. Sequential File Organization
In a sequential file, records are arranged in the ascending or
descending order or chronological
order of a key field.
To access these records, the computer must read the file in
sequence from the beginning.
The retrieval search ends only when the desired key matches
with the key field or the currently
read record.
Applications
Payroll System
Billing and customer statement preparation
Bank cheque processing
Financial accounting
15. Advantages
1. Easy to organize, maintain, and understand.
2. Relatively inexpensive I/O media and devices can
be used.
3. It is the most economical and efficient file
organization where the activity ratio (the ratio of
the total number of records in transaction file and the
total number of records in master file)
is very high. That is why this file organization is most
suitable for transaction files.
16. Disadvantages
1. It proves to be very inefficient and uneconomical for
applications in which the activity ratio
is very low.
2. Since an entire sequential file may need be read to
retrieve and update few records,
accumulation of transactions into batches is required.
3. Transactions must be stored and placed in sequence
prior to processing.
4. Timeliness of data in the file deteriorates while batches
are being accumulated.
5. Data redundancy is typically high since the same data
maybe stored in several files,
sequenced on different keys.
17. Direct or Random File Organization
A direct file (also referred to as a relative or random
organization) consists of records organized in
such a way that it is possible for the computer to directly
locate the desired record without having
to search through any other records first.
A record is stored by its key field.
A Direct Access Storage Device (DASD) such as drum, disk,
etc., are essential for storing a direct file.
18. Advantages
1. The access to and retrieval of a record is quick and direct
(within a fraction of a second).
2. Transactions need not be sorted and placed in sequence
prior to processing.
Disadvantages
1. These files must be stored on a direct access storage
device. Hence, relatively expensive
hardware and software resources are required.
2. File updation (addition and deletion of records) is more
difficult as compared to sequential
files.
3. Address generation overhead is involved for accessing
each record due to hashing function.
19. Applications
A direct file organization is most suitable for interactive on-line applications such as:
1. Airline/Railway reservation systems
2. Teller facility in banking applications
Indexed Sequential File Organization
Basic principle "having index (directory)"
e.g.: A directory (index) in a large multistoried building that helps one to locate a particular person's
room within a building instead of searching door by door.
The contents (which serve as an index) help us to locate (page of the desired topic) so that one can turn
directly to that page to begin reading instead of searching each page.
Indexed sequential files use exactly the same principle.
In an indexed sequential file, records are stored sequentially on a direct access device (i.e., magnetic
disk) and data is accessible either randomly or sequentially.
The sequential access of data occurs as one record at a time until the desired item of data is found.
The records of the file can be stored in random sequence but the index table is in sorted sequence
on the key value.
This technique is known as Indexed Sequential Access Method (ISAM).
20. Advantages
1. Permits the efficient and economical use of sequential processing techniques
when the activity ratio is high.
2. Permits direct access processing of records in a relatively efficient way when
the activity ratio is low.
Applications
File System and Data Base
This file organization is a compromise approach that combines some of the
advantages of both
the sequential and direct approaches, and therefore used in almost all the
applications, like
Material A/C, Banking Industry, etc
