Object access method: Difference between revisions

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{{Short description|Programming function available in z/OS}}

{{Mainframe_I/O_access_methods}}

{{Refimprove|date=September 2014}}

'''Object access method''' ('''OAM''') is an [[access method]] under [[z/OS]] which is designed for the storage of large numbers of large files, such as images. It has a number of distinguishing features, e.g. compared to [[Virtual storage access method|VSAM]]:

*OAM datasets do not have anyan internal record structure,; they are accessed as binary data streams.

*OAM datasets are not directly catalogued. Rather, they are stored into OAM collections, with only the OAM collection being catalogued. The reason for this is to prevent the catalogue from being overloaded with large number of e.g. image files.

*OAM datasets are not directly cataloged. Rather, they are stored into OAM collections, with only the OAM collection being cataloged. The reason for this is to prevent the catalog from being overloaded with large numbers of (e.g. image) files.<ref name="HardingClark1990">{{cite journal|last1=Harding|first1=W. B.|last2=Clark|first2=C. M.|last3=Gallo|first3=C. L.|last4=Tang|first4=H.|title=Object storage hierarchy management|journal=IBM Systems Journal|volume=29|issue=3|year=1990|pages=384–397|issn=0018-8670|doi=10.1147/sj.293.0384|quote=The ability to locate existing objects in storage is fundamental to any data processing system. The facility that carries out the locate function for data sets in an MVS system is the catalog. Typical MVS systems may have tens or even hundreds of thousands of data set entries recorded in a hierarchy of catalogs. In contrast, OAM must be able to manage hundreds of millions of objects, which if individually cataloged would require an excessively large catalog... The system catalog was extended through the concept of collections to handle the large numbers of objects expected for image applications. A catalog entry is defined for each collection, and provides the default storage class and management class assignments for objects stored in the collection, and the identifier of the storage group where the collection is physically stored.}}</ref>

OAM is meant to be used in conjunction with [[IBM_DB2|DB2IBM Db2]]. An example use case for OAM would be storing medical images in a DB2Db2 database running under z/OS.

==History==

OAM was created in the 1980s "as a prototype product for an insurance company to replace [[Microform#Microfiche|microfiche]]." Initially OAM supported optical storage and magnetic disks. In the 1990s support for [[Magnetic tape data storage|magnetic tape]] was added. In 2011 support was added for storage of objects in a z/OS unix file system&mdash;either [[zFS (z/OS file system)|zFS]] or [[Network File System|NFS]].<ref name=Vitse>{{cite journal|last1=Vitse|first1=Caroline L.|title=Reintroducing Object Access Method|journal=IBM Systems Magazine|date=September 2011|url=http://www.ibmsystemsmag.com/mainframe/storage/Data-Management/reintroducing_OAM/|accessdate=Sep 4, 2014|archive-date=September 4, 2014|archive-url=https://web.archive.org/web/20140904044949/http://www.ibmsystemsmag.com/mainframe/storage/Data-Management/reintroducing_OAM/|url-status=dead}}</ref>

In the 1990s, Object Access Method was used by the [[Canadian Intellectual Property Office]] to store documents related to patent processing.<ref name="Taylor1995">{{cite journal|last1=Taylor|first1=Ray H.|title=TECHSOURCE: a project to automate the patent operations of the Canadian Intellectual Property Office|journal=World Patent Information|volume=17|issue=3|year=1995|pages=159–164|issn=0172-2190|doi=10.1016/0172-2190(95)00017-T|bibcode=1995WPatI..17..159T |quote=The IODM uses data from within its DB2 database tables to determine the ___location of the documents and retrieves them using the Object Access Method (OAM).}}</ref>

==References==

{{Reflist}}

==External links==

* [https://share.confex.com/share/116/webprogram/Handout/Session9008/SHARE_Anaheim11_9008_OAM.pdf DFSMS Object Support:Data Archiving with OAM]

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