41 lines
2.2 KiB
Plaintext
41 lines
2.2 KiB
Plaintext
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<?page
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title=>LiveJournal Protocol Versions
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body<=
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<?h1 Protocol Versions h1?>
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<?p
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The LiveJournal protocol (so far) has been more or less static; while new
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modes have been added, the basic operation has not changed much. However, recent
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introduction of Unicode support in LiveJournal necessitated changes in the way
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text is encoded in protocol requests and responses. In order to allow new clients
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to take advantage of Unicode support and at the same time avoid breaking existing
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clients, a versioning scheme has been put into the protocol. The client sends
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the number of the highest protocol version it supports in every request, inside
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a <b><tt>ver</tt></b> attribute; version 0 is implicit if the client does not
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send the <b><tt>ver</tt></b> attribute. Currently there are two versions of the protocol,
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and the Unicode-enabled server code supports both of them.
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p?>
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<ul>
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<li><b>Version 0</b><br/>
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If a client does not send a <b><tt>ver</tt></b> key on a request, it assumed to support
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protocol Version 0. In protocol Version 0, textual information transmitted from or to the
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server is always assumed to be a stream of 8-bit bytes, not necessarily ASCII, but without
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any guarantee that the non-ASCII bytes are presented in any particular encoding.
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<li><b>Version 1</b><br/>
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Version 1 differs from Version 0 only by imposing additional requirements on the text
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transmitted through requests and responses; there aren't any changes in protocol modes.
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The additional requirements are that in a Version 1 request, the client <b>must</b> transmit
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all textual information as a stream of Unicode data encoded in UTF-8; the server <b>must</b>
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respond to Version 1 requests with Version 1 responses; in such Version 1 responses, the server
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<b>must</b> also transmit all textual information encoded in UTF-8; and the client must expect
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that and handle such responses correctly.
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In other words, all information transmitted via protocol when Version 1 is used is always encoded
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in UTF-8. UTF-8 is a representation of Unicode in a bytestream format compatible with ASCII. See
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<a href="http://www.unicode.org">the Unicode Consortium website</a> for more information on Unicode
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and UTF-8.</li>
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</ul>
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<=body
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page?>
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