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Additional
JRIO documentation is available in both HTML and PDF formats.
JRIO is an integral part of the IBM Developer Kit for OS/390, Java 2 Technology Edition and the IBM SDK for z/OS, Java 2 Technology Edition. Refer to the
Java™ on z/OS website for information on the requirements for downloading and installing either of these products.
JRIO lets Java applications access traditional OS/390 file systems in addition to the Hierarchical File System (HFS). JRIO makes it easier for Java applications to access records within files and to access file systems through native methods when
java.io Application Programming Interfaces (APIs) do not support those file systems.
JRIO is a class library, similar to
java.io. While
java.io provides
byte-oriented or
field-oriented
access to files, JRIO provides
record-oriented access. While
java.io provides sequential and random access, JRIO applications read, append, and update records by providing the following types of access:
What JRIO helps you do
JRIO lets record-oriented applications (supporting multiple file systems) run using files on different file systems. It also provides a set of OS/390 native code drivers to access:
- Virtual Sequential Access Method (VSAM) data sets (KSDS only)
- Non-VSAM record-oriented data sets
- The system catalog
- Partitioned data set (PDS) directory
JRIO provides indexed I/O access to records within a VSAM Key Sequenced Data Set (KSDS). The VSAM support uses OS/390 native code to provide a set of concrete classes that implement the KeyedAccessRecordFile class. This lets you access records:
- In entry sequence order
- By primary unique key
- By alternate unique or non-unique key
JRIO focuses on providing sequential and random I/O access to record-oriented data within non-VSAM sequential data sets and PDS.
The non-VSAM support uses OS/390 native code to provide a set of concrete classes and new directory classes that use underlying non-VSAM physical record files. This includes:
- Listing the High Level Qualifiers (HLQ) from the system catalog
- Listing data sets for a given HLQ
- Listing the members of a PDS
JRIO provides support for sequential and random I/O access to records within HFS files. The HFS support uses pure Java code to provide a set of concrete classes and directory classes that use the underlying
java.io.
JRIO also provides navigational support for HFS directories.
Comparing JRIO and java.io
The following table summarizes some differences between
java.io and JRIO:
| java.io
|
JRIO
|
| stream of bytes or fields |
stream of
records
|
| sequential and random access |
sequential, random,
and keyed access
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| binary and text files |
binary files only -- binary and text
fields
|
| concrete classes |
interfaces, handles, and concrete classes |
| data input stream |
nonapplicable |
For more information
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