Library 4.1 Release Notes
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The focus for version 4.1 of the W3C Reference Library
is to provide a set of higher level, application specific APIs for accessing
the Web. These APIs - called profiles
- will help the application, a Web client for example, to more easily use
the full potential of the application independent
Library core. Also, the Library contains
a significantly better interface for easy access to the Web through a
large set of functions specialized to
perform certain Web operations like PUT
, POST
,
DELETE
, GET
and HEAD
.
Check out the latest
list of public functions
Release 4.1b5 August 24 1996
Release 4.1b5 is mainly a bug fix release after intensive testing against
the Common Lisp Server which also
isa HTTP/1.1 application. However, it also has a few new features worth noting.
New Features
-
Added support for the entity-tag validator headers:
If-Match
and If-None-Match
and also for the
date validators If-Modified-Since
and
If-Unmodified-Since
. We only use either etags or date stamps
and the entity-tag validators have precedence over the date
validators.
-
Added acinclude.m4 in the WWW directory. The
file is used by automake
-
Changed the configure script to handle the
location of the icons distributed as part of the libwww distribution package.
-
Added full support for
Cache-Control
header and
Connection
header. Both headers can have an association list
of name value pairs as directives.
-
Moved the memory cache handler (history handler) from the
line mode browser to be a BEFORE
filter which can be used by other applications
as well. It is now included as part of the
client profile.
-
Changed the expiration handling API to not
include any notification messages. Any messages to be transmitted to the
user is now handled by the Alert manager.
-
Added persistent cache manager to the
client profile.
-
Added validation command to the line mode browser
-
Changed the cache validation management in the
Request object. The validation scheme is now
compatible with HTTP/1.1 caching including handling of the history list.
We have changed the validation enumerations from
-
HT_ANY_VERSION
, HT_MEM_REFRESH
,
HT_CACHE_REFRESH
, HT_FORCE_RELOAD
-
HT_CACHE_OK
, HT_CACHE_FLUSH_MEM
,
HT_CACHE_VALIDATE
, HT_CACHE_FLUSH
.
Bug Fixes
-
Fixed problem when getting a
connection
header with the
close
directive. The problem caused libwww to loop as it recursively
tried to free the input stream pipe
-
Fixed bug in access authentication which could cause libwww to loop if the
top level of the site was protected.
-
Fixed bug that caused a core dump if receiving a message body without any
content-type
. Now the data is passed to the
guessing stream which hopefully can handle
it.
Release 4.1b4 August 20 1996
HTTP version 1.1 allows for effective use of persistent connections. However,
in orderto make this work, a client application must be capable of recovering
from a closed connection between sent requests. The beta 4 version of libwww
supports automatic connection recovery and provides the functionality for
performing pipelining of requests. That is, there can be multiple outstanding
requests on the same connection In order to do this, the release contains
modifications to the Channel Object,
the Host object and the
Net object.
New Features
-
Added support for case-insensitive searching for proxies via environment
variables
-
Added support for proxy authentication
-
Changed handling of proxies so that they are not included in the URL but
is now instead part of the request object. This allows for better handling
of proxies and also for more freely use of the proxy filter as it doesn't
affect the other filters anymore.
-
Added support for TRACE HTTP method in the
HTAccess module.
-
Updated News DLL and incorporated News patches from Maciej Puzio
-
HT_PERSISTENT
is now obsolete and should be replaced by
HT_PENDING
-
The
HTChannelMode
enumeration describing the flow of a channel
has been replaced by HTTransportMode
as it is now a part of
the transport object and not the channel object
-
HTNet_idle()
has been removed and replaced by
HTNet_isIdle()
. The function returns YES if there are no pending
requests in libwww at all.
-
Add support for checking public information about a host and use this information
when issuing a PUT, for example. Also add check for host element in
HTAccess when doing PUT. We may have public
information available
-
Changed the return codes defined in HTUtils
to reflect the values of the HTTP spec.
-
Added support for
305 Use Proxy
redirections
-
Updated HTDir module to better use the fact
that we know that an entry is a directory or not. Now it appends a '/' to
the URL if it is a directory. That way we often avoid a redirection.
-
Removed WWWRules as interface and merged it with the
WWWApp interface. The reason was that the
two were highly alike and depended on each other
Bug Fixes
-
Fixed problem with uploading directory listing using chunked encoding
-
Fixed autoconf to handle WAIS and updated the HTWAIS.c module
-
Fixed race problem in PUT on alphas
-
Tested reentrant version of libwww (uses
_REENTRANT
define)
-
Fixed problem in file name conversion from URL to local format on Windows
Release 4.1b3 July 20 1996
This release contains a TCL add-on to the Robot
example application and a Deja GNU Test suite
for the Library. Also, it support HTTP/1.1
including persistent connections, two-way PUT
, and the
host
header. There is also a sample PEP
implementation, that although incomplete can give an idea of where we're
headed using PEP.
The file access module now does content
negotiation by default. This means that all local file access (including
from client applications) do content negotiation when accessing local
files. Content negotiation can be turned off by setting a flag in the
request object.
A main difference in beta 3 is that we now have a set of
"application profiles" that helps the
application to initialize libwww core to
work as a typical client, robot or other type of application. This should
replace the huge initialization procedure seen in previous versions. This
is in fact a result of the core being so flexible - it is inly a framework
for accessing the Web. The application must initialize all the functionality
at run-time. You can see the various profile functions in the
WWWInit interface.
The second main difference is that the BEFORE and AFTER filters
have been more explicit than before. The HTLoadStart
and
HTLoadTerminate
functions actually covered many typical
BEFORE and AFTER filter functions like looking for proxies,
searching the cache, looking for rule file matching, and logging etc.
However, two functions were not covered by this: redirection and
authentication. That is why the application in previous version had
to supply this functionality. However, in beta 3 we have split up the
HTLoadStart
and HTLoadTerminte
functions into a
set of filters which each perform only
a single function, for example looking for proxies. The split has two functions:
first it shows how you can use filtes to add new functionality to the Library
and second it can be used by more types of applications. A result of the
new filters is that we also have default redirection and authentication filters
so you don't have to provide this anymore.
The filters are set up as part of the
profiles so you will normally not have
to register them individually.
New features and Changes
-
Introduced HTUserprofile class to handle
host and user specific information
-
Added Chunked decoding and encoding module
-
A host name is not expanded to a fqdn name as it is not reliable enough.
Now we just keep it as is, that is we don't expand www to
www.w3.org, for example.
-
Updated HTML parser to support
BASE
tag and LINK
tag
-
Added new access methods to the HTAccess
module. It is now part of the WWWApp
interface
-
Updated the Icon module and added icons
to the distribution file
-
Added a Stream to Chunk converter for
easier conversion of streams into dynamic memory buffers
-
Introduced HTLib as a new core module. It
contains generic information about the core which used to be in the HTAccess
module.
-
Added support for HTTP/1.1. Most of the HTTP/1.1
specification is now in place, we still need some headers and some features
but this version can be considered to be compliant.
-
Added suport for proxy authentication as specified by HTTP/1.1
-
Added support for case-insensitive searching for proxies via environment
variables
-
Changed handling of proxies so that they are not included in the URL but
is now instead part of the request object. This allows for better handling
of proxies and also for more freely use of the proxy filter as it doesn't
affect the other filters anymore.
Bug Fixes
-
Fixed problem with uploading directory listing using chunked encoding
-
Fixed problem in the rule file parser. It didn't parse the last line of the
config file
-
Fixed autoconf to handle WAIS and updated the
HTWAIS.c module
-
Fixed race problem in PUT on alphas which caused the PUT operation to hang
under certain circumstances
Release 4.1b1 May 20 1996
New Features
-
Introduced GNU autoconf configure script for compiling on Unix platforms
instead of the old BUILD script. This should make it a lot easier to compile
on Unix as we get all the advantages of GNU autoconf.
-
Introduction of the HTUserprofile Class which
keeps track of a "user" known to the Library
-
New access authentication interface allowing for dynamic registration of
new access authentication mechanisms. It provides an easy API for hooking
in new schemes.
-
Improved handling of trace messages which allows for easy redirection of
trace messages
-
Support for registration of content coders/decoders and content transfer
encoders/decoders. This is done the same way as for media types by registering
a set of streams that can handle the various encodings.
-
Support for chunked decoding
-
Introduction of the HTHost Class which keeps
track of information about remote hosts
-
The DNS Class has been simplified to handle
DNS queries only. All additional information about the remote host is defined
by the HThost Class.
-
We have a new HTEvent module which allows
for dynamic registration of an event manager. This will make it much easier
to use external event managers together with libwww. If you wish to continue
to use the event loop from HTEvntrg, you must register it explicitly with
HTEventrgInit. This call is demonstrated
in HTBrowse.
-
The HTStream module has been created
containing a set of basiv streams such as an error stream etc.
-
Introduction of the HTTransport Class.
This allows for dynamic registration of transport protocols such as for example
the W3Mux protocol, TCP access, local file access etc.
-
All MIME parsing is now done with registered parsers. The
HTMIME module only unwraps the MIME
header fields and calls the best parser. The header parsing origonally done
in HTMIME can be found in HTInit.c and is
registered with HTMIMEInit. This call is
demonstrated in HTBrowse.
Henrik Frystyk Nielsen, libwww@w3.org,
@(#) $Id: ReleaseNotes.html,v 1.36 1996/08/21 14:13:11 frystyk Exp $