Compile Time:

Override File

QTAPE to

File FMT1

RPG program

File name = QTAPE Format = E Device = SEQ

File Locking

FMT1

Execution Time:

No Override

QTAPE

File type =

DEVICE

Device type =

TAPE

Figure 137. Redirecting File Input and Output Example

File Locking

The OS/400 system allows a lock state (exclusive,

exclusive

 

allow

read,

update,

shared

no

update,

or

shared

for

read)

to

be

placed

on

a

the

execution

of

a

job.

Programs

within a

job

 

are

not

affected

b

file

lock

state

applies

only when

a

program

in

another job

tries

to

currently. The

file

lock

state

can

be

allocated

with

the

CL

command

cate

Object).

For

more

information

on

allocating

resources

and

lock

sta

Data

Management manual.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The OS/400 system places the following lock states on database files opens the files:

File Type

Lock State

 

 

 

 

 

 

Input

Shared

for

read

 

 

 

 

Update

Shared

for

update

 

 

 

 

Add

Shared

for

update

 

 

 

 

Output

Shared

for

update

 

 

 

 

The

shared-for-read lock state allows another

user to open the file

of

shared

for

read, shared

for

update, shared no update,

or

exc

but

the user cannot specify the exclusive

use of the file. The s

state

allows

another

user

to

open

the

file

with

shared-for-read

or

lock

state.

 

 

 

 

 

 

 

 

 

 

 

 

 

The

RPG program places an exclusive-allow-read

lock state on device fi

Another

user

can

open

the

file with a

shared-for-read

lock

state.

The

lock state placed on the file by the

RPG

program

can

be

chang

the

Allocate

Object

command.

 

 

 

 

 

 

 

 

 

Chapter 15. General File Considerations275

Page 299
Image 299
IBM AS/400 File Locking, Data Management manual, Program Can Chang Allocate Object

AS/400 specifications

The IBM AS/400, now known as the IBM iSeries, is a midrange computer system that has been a cornerstone of enterprise computing since its introduction in 1988. Designed to provide a robust platform for business applications, the AS/400 is celebrated for its reliability, scalability, and integrated database capabilities.

One of the key features of the AS/400 is its Integrated Operating Environment, which blends hardware and software resources seamlessly. This integration allows businesses to execute diverse workloads, ranging from traditional applications to modern web-based services, all on a single platform. The operating system, OS/400 (now IBM i), offers a rich set of APIs and tools for developers, simplifying application development and management.

Another standout characteristic of the AS/400 is its built-in database, DB2 for i. This powerful relational database management system allows for efficient data handling and provides advanced features such as support for SQL, XML, and JSON, making it easier for businesses to manage their data and integrate it with other systems. The database's tight integration with the operating system enables high performance and security.

In terms of scalability, the AS/400 can accommodate small businesses as well as large enterprises, with the ability to support hundreds of users simultaneously. Its architecture allows for easy upgrades in hardware, meaning that organizations can scale their systems without replacing the entire infrastructure.

Security is another critical attribute of the AS/400. With a sophisticated security model, it offers built-in user authentication, access control, encryption, and auditing capabilities to protect data and applications from unauthorized access.

The AS/400 also supports multiple programming languages, including RPG, COBOL, Java, and PHP, giving organizations the flexibility to choose the development tools that best fit their needs. This diversity helps maintain legacy applications while also developing new ones that leverage modern technologies.

Moreover, the platform supports both traditional green-screen interfaces and modern graphical user interfaces, allowing organizations to transition smoothly into contemporary user experience paradigms.

Overall, the IBM AS/400 stands out as a resilient, flexible, and secure computing platform that enables organizations to effectively manage their business operations, streamline processes, and adapt to changing market demands. Its unique combination of integrated features and capabilities ensures that it remains relevant in today's fast-paced technology landscape.