Editing OSCAR protocol (section)

{{Short description|Instant messaging and presence information protocol}}
{{Infobox networking protocol
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| purpose      = [[Instant messaging]]
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'''Open System for Communication in Realtime''' ('''OSCAR''') is [[AOL]]'s [[Proprietary protocol|proprietary]] [[instant messaging]] and [[presence information]] [[Protocol (computing)|protocol]]. It was used by AOL's [[AOL Instant Messenger|AIM]] instant messaging system and [[ICQ]].

Despite its name, the specifications for the protocol remain proprietary. AOL has gone to great lengths to keep competitors (namely [[Microsoft]], [[Extensible Messaging and Presence Protocol|XMPP]], and Cerulean Studios) from implementing compatible clients for their proprietary messaging systems.<ref>{{cite web| url = https://www.theregister.co.uk/2002/01/31/aol_blocks_trillian_im_access/| title = AOL blocks Trillian IM access • The Register| website = [[The Register]]}} </ref><ref>{{Cite web |url=http://www.geek.com/news/aol-vs-trillian-continues-548381/ |title=AOL vs. Trillian continues &#124; News &#124; Geek.com |access-date=2018-02-05 |archive-date=2016-09-18 |archive-url=https://web.archive.org/web/20160918001136/http://www.geek.com/news/aol-vs-trillian-continues-548381/ |url-status=dead }}</ref> In 2002, AOL signed a contract with [[Apple Computer|Apple, Inc.]], allowing them to use OSCAR (as well as AOL's own code libraries) in their [[iChat]] application. This allowed iChat users to interact with ICQ and AIM users directly. The deal also permitted users of Apple's [[.Mac]] service to [[Login|log in]] to the AIM network using their .Mac email addresses. (This has carried over to Apple's [[MobileMe]] service.)

{{As of | 2009}}, large parts of the protocol had been [[reverse engineering|reverse-engineered]] and implemented by a number of third-party clients.

The OSCAR protocol can be used separately from AOL's network. In fact, AOL expands on the general concept of OSCAR, adding systems for service-side buddy lists and icons, as well as features for file transfers using [[Bonjour (software)|Bonjour]].

On March 6, 2006, AOL released the AIM [[Software development kit|SDK]] and launched a developer website, allowing developers to build plugins for [[AIM (software)|AIM Triton]], and build their own custom clients, which connect over the OSCAR protocol. They had not, at that point, however, released any information about the protocol itself.

On March 5, 2008, AOL released portions of the OSCAR protocol documentation. Google also provided the ability to sign in to AIM network via the [[Google Talk]] client built into [[Gmail]].