News for version 3.14.0

News for version 3.13.3

Memory leak fix in RValue.cc - affects server function evaluation only.

News for version 3.13.2

Fixed a memory leak in the CE parser when evaluating server functions.

News for version 3.13.1

Fix for a unit-test that uses the default server at test.opendap.org. 
This affects neither the API nor ABI of libdap; only the test baseline
was changed.

News for version 3.13.0

Added a xml file to serve as input for the perl-based abi compatability 
checker. Seems to be pretty slick; see abi-checker.xml.in for more info.

Some updates - mostly addition of #include <unistd.h> - for OSX 10.9's
clang compiler.

News for version 3.12.1

Fixed the behavior of Sequence::read_row() so that the documented
semantics of read() are used. This will require changes in some of the
handlers but does not change the libray's ABI. Handler's that don't
need the new/corrected behavior can use version 3.12.0.

News for version 3.12.0

Moved server functions out of libdap; they are now stored in a BES module.

Added support for building large (constant) arrays to be used in
server functions. The arrays are defined using a new special form that
the ConstraintEvaluator class supports. The server side functions are
now in their own BES module (built as part of the BES for now) and
it's possible to name the constant arrays. Arrays of 1 million
elements can be made in a fraction of a second (although it will take
longer to send the constraint to the server). See the README file for
more details.

News for version 3.11.7

Bug fix for the server function caching code. Now if the function
cache directory /tmp/dap_functions_cache exists, it will be used to 
cache the results of applying server functions. If the directory does
not exist, then the function results won't be cached - a minor 
performance penalty in most cases. 

The size of the cache is set to 20GB. The size and location of the 
cache are fixed for this version of libdap but they will move into
the bes.conf file as parameters in a future version of the server.

News for version 3.11.6

Changes to the way constraints are evaluated when they contain server
functions. Now DAS and DDS objects can be returned from requests that
include those constraints. The server function call results are
cached, so that sending the same function calls several times will not
evaluate those functions more than once.

News for version 3.11.5

Fixed a memory leak in XDRStreamMarshaller and a bug in
DDS::add_var_nocopy().

News for version 3.11.4

Merged to trunk; tagged.

News for version 3.11.3

Changed the return value for dap-config --libs so that it does not contain 
the curl static libs. This causes problems whenlinking on CentOS 6 in some
cases.

News for version 3.11.2

The new DAP3.3 Keywords are supported by the library. These are sort
of a hidden feature of DAP4 that might not be used.

There are many bug fixes in this update; check the ChangeLog or Trac.
Two notable fixes:

* The way attributes are encoded has changed subtly so that now only
  spaces are escaped. This fixes a problem with our XML and RDF
  responses.

* The XML output (i.e., the DDX) is now built using an XML library, so
  any encoding issues are its fault ;-) But, in a pragmatic sense,
  this has greatly simplified the library and sets the stage for
  further simplification of the methods that build responses. The
  behavior of those methods has not changed.

News for version 3.11.1

Merge of the Hyrax 3.6.2 fixes.

A race condition in the HTTP cache was fixed.

Fixes for the OS/X package.

News for version 3.11.0

Constraint expressions can now include multiple function calls.
Previously, when a function was used in the projection part of the CE
and it was not a 'projection function,' but a function that returns
data, only function could be called in the CE. Now the evaluator
supports calling a series of functions. The results are returned in a
Dataset object as before. Because this is a new behavior for the
library I have bumped up the minor revision. This version is backward
compatible with the previous version of the library.

Grid now prints the XML declaration correctly when a constrained Grid
variable's type decays to a Structure. The expr-test program now has
an XML option (-x) for use with constrained DDS/DDX output. This bug
affected the usefulness of the DDX response.

the geogrid() function now takes both (grid, <box points>) and (grid,
lat array, lon array <box points>). This includes some minimal testing
of the new code.

Bug fixes.

News for version 3.10.2

Changed the way the DAS object's attributes are merged into a DDS
object, which did two things. First, the process of merging the
attributes has a default behavior that will work if the DAS and DDS
are built according to the DAp 2.0 specification, and second, the
handlers can specialize the process to suite their own needs. This
means that new handlers that build odd DAS objects will need to
specialize the transfer_attributes() method defined by BaseType,
Constructor and Grid. I've already done this for the current handlers
we're distributing as part of Hyrax. This means that attributes from
the netCDF handler appear correctly in Grid maps.

Speaking of the netCDF handler, it now builds with netcdf 4.1.

Build fixes galore, including new Requires: lines in the rpm spec
files which should make it easier to short circuit installation
problems with the handlers.

The DDX no longer contains attributes with &0xdd; escape codes. When
an XML document declares that it is UTF-8 codes < 0x20 are not
allowed. We're using octal escapes again.

The preceding fix, along with the corrected processing of the DAS
object mean that two major issues with the DDX that hindered the use
of that response in semantic web applications are gone.

News for version 3.10.1b

We have removed the Server 3 (CGI) software from the dap-server
package and, with that change, we have removed the deflate program
from this library/package.

The geogrid() function has been much improved. It will now answer
requests where the latitude is upside down in the dataset and flip the
result so that the north pole is 'up'. It will also handle requests
that 'wrap around' the date line. Error messages are also improved.

This library now implements DAP 3.3 including the OtherXML DAP
attribute type (which will become AnyXML in DAP 4). The library now
implements simple version negotiation and a DDX response that is DAP
version sensitive. See the online DAP4 design documentation for more
information (docs.opendap.org).

Many, many fixes and extensions for DAP4 and NcML support. (NB: the
NcML handler is a separate project).

News for version 3.9.2

Memory leak fixed when using DDS::transfer_attributes on a DAS that uses the
ALias keyword.

News for version 3.9.1

The CE parser now returns an error if an array of structures that contains
arrays is imporperly constrained (the enclosing structure array _may_ be
subsampled, but that subsampling must be the same for each of its fields. The
fields can be independently subsampled.

A problem with the client-side cache has been fixed.

Variable names can now be quoted! That is, in a CE you can say:

  "my odd name"."% H2O"[10:13] 

and it will parse. Must clients and all web browsers will encode all of this
using the web's URL escape syntax, whic his hard to read, but this means that
any character can now appear in a variable name (double quotes can be escaped
using a backslash and backslashes can be includes using '\\'). The quotes are
optional, of course, so all CEs that work now will continue to work.

News for version 3.9.0

libdap now supports DAP 3.2. The evolving DAP 3.x protocol is described at
http://docs.opendap.org/index.php/DAP3/4. The most important change from DAP
3.1 to 3.2 is:

  DAP 3.2 introduces the notion of protocol negotiation, similar to HTTP's
  response type or encoding negotiation. The client MAY send an XDAP-Accept
  header to tell the server the highest version of the protocol that the
  client can understand. The server MUST then respond using only responses at
  or below that version number of the protocol. Note that an Error response
  (e.g., "The response you requested cannot be returned using the protocol
  version you understand") can be understood by any client. If a client does
  not send the XDAP-Accept header, then the server MUST assume a DAP 2.0/3.1
  client. The only functional difference between DAP 2.0, 3.0 and 3.1 is
  form/content of the version information returned in the HTTP response
  header.

  By allowing the server to respond with a lower version the protocol can
  support old servers (since that's how they will respond) and enable newer
  clients to treat the lower version responses as errors (because the newer
  servers can be expected to discriminate between different server versions).

  New servers SHOULD always return a response that conforms to the version
  sent from the client in the XDAP-Accept header.

  In addition to returning the DAP protocol version using the XDAP header
  (which is a mechanism specific to HTTP), the protocol version will also be
  returned in the DDX Dataset element using the XML attribute dap-version.
  See DDX.

With this version of libdap the DDX is slightly different for DAP 3.2 - it
now includes DAP protocol version information and an xmlbase element.

There was ambiguity regarding how an array of structures would be constrained.
The web page of DAP 2 Errata has been updated with a clarification of this and
the constraint expression parser has been updated to reflect that fix. See
the DAP3/4 page and ticket 975 for the complete info. Short version: Suppose
's' is an array of structures and 'm' is an array that is a member of 's'.
You can constraint 'm' like this: s2[0:4].m[2:7]

Now the notion that a dataset identifier (e.g., a file name) is bound to the
DDS has been  dropped and that identifier is bound to a variable. This lets
the library be used in contexts where a DDS holds variables from several
different places (e.g., files).

String attribute values were always quoted (quotes were added if not present
in the data set) and while this was OK for the DAS response, it broke the
DDX. Now quotes are added to DAS response but not the values themselves. See
ticket 1163.

Nested Sequences were failing when the constraint forced one or more rows of
the inner Sequence to be empty. Fixed.

A number of build issues have been fixed in this version, see the ChangeLog
file.

News for version 3.8.2

Significant improvements to the HTTP cache. The cache software could return
erroneous responses in some rare cases when using multi-threaded code. Fixed.
Also the entire caching system is now much more robust since the 'table' that
contains information about individual entries is encapsulated in it's own
class. The HTTP cache is still both thread-safe and _not_ multi-process safe.
However, it should be possible to modify the HTTPCacheTable class to use a
database system like MySQL or SQLite to make it MP-safe.

The 'ancillary information' functions have been moved to their own class
(from DODSFilter and the file cgi_util.cc).

I fixed the libdap win32 installer so that it does not install stuff in the
win32 system directories anymore.

News for version 3.8.1

The syntax for PROXY_SERVER and NO_PROXY_FOR have been fixed so that they are
easier to use. PROXY_SERVER now takes a value like
'http://user:pw@squid.proxy.edu:3128' and uses it correctly. In that value,
all parts but the host name (squid.proxy.edu) are optional and the old syntax,
as well as several comman variants, are accepted. For the NO_PROXY_FOR entry,
the '<protocol>,' is now optional. Only the HTTP protocol is supported or the
proxy server.

News for version 3.8.0, 29 February 2008

The libdap classes and code are now inside of the libdap namespace. In order
to access any of the classes, for example, you will need to do one of the
following. After including the libdap headers you can:

1. add a using statement for the entire libdap namespace:

using namespace libdap ;

2. add a using statement for the classes that you will be using:

using libdap::DAS ;

3. inside your code scope the use of libdap classes.

libdap::DAS *das = code_to_get_das() ;

HTTPCache updated to cache an entry, returning not only the FILE pointer but
also the name of the file in the cache. This way, the cached item could be
passed to a data handler, such as the netcdf_handler, and read.

The pkg build for Mac OSX was updated to automate the creation of the
ReadMe.txt file, add a README and NEWS file to the dmg and automatically
create the dmg using DropDMG.

News for version 3.7.10, 28 November 2007

Fixed XDRStreamMarshaller so that it no longer allocates a huge buffer. This
fixes a bug where the BES fails to start on smaller machines.

News for version 3.7.9, 21 November 2007

Bumped up the soname version numbers for libdaoclient and libdapserver due
to changes in the HTTPResponse and AlarmHandler interfaces.

The transfer_data() method defined for Sequence and Structure has been
generalized and implemented for all classes. In the process, so issues with
the way nested sequences were handled have been fixed. I renamed the method
to intern_data() since it is now a part of libdap (and not just two classes).
The method uses the read() methods defined for the type classes (Byte, ...,
Grid) to read data into variables in a DDS as if they were read in using
deserialize(). This is used by the ASCII response generator and might be used
by other 'formatted output' generators.

Generated files (like the grammar files) are now shipped with the source
distributions. (From Patrice Dumas)

Methods which write output using the C++ iostream system have been added back
into the library and are going to replace the FILE* versions of those
methods. We have also added an 'Un/Marshaller' set of classes so that we can
release a version of Hyrax (slated to be 1.4) that will improve BES/OLFS
communication efficiency.

The functionality of the Passive* type classes was subsumed by their parent
classes and they were removed from the library to cut down on 'hierarchy
clutter.' Some other unneeded files were also removed.

The maximum size of a Str object was changes to 65535 (DODS_USHORT_INT-1) to
accommodate HDF5 strings. 

Checkouts from subversion now have no (?) generated files. We are keeping a
copy of the grammars in subdirectory named 'grammarfiles.'

HTTP response codes are now available in libdap HTTPResponse objects. From
Darren Hardy.

News for version 3.7.8, 26 June 2007

Updated the email address for support to support at opendap.org and changed
the tech email list address to opendap-tech at opendap.org. This is part of
the plan to shift support services to OPeNDAP and to use the tech email list
as part of that plan.

Updated to the latest gnulib software.

Memory errors fixed: 

    In the HTTP processing code for clients which was triggered when a client
    read from an older server (older servers had malformed HTTP headers).

    An error in the regular expression class (Regex) where the build
    generated flawed code on a 64-bit machine.

OSX Build improvements.

Patrice Dumas' changes to dods-datatypes.h - Now the header uses the C99
types unless the stdint.h header is not present.

pkg-config support. From a patch by Patrice Dumas.

General improvements to comments, strings and error messages throughout the
libraries. 

News for version 3.7.7, 2 May 2007

Fixed a bug where the build was not installing the dapserver and dapclient
libraries. 

Fixed a handful of platform-specific build issues.

There are some minor performance improvements to the constraint evaluator.

Repaired some problems with the server-side functions.

News for version 3.7.6, 12 March 2007

Fixed a bug in the linear_scale() Constraint Expression function when that
function was used with plain arrays.

I fixed a build issue on linux for ml-structs caused by a bad/missing
#include in GnuRegex.h.

News for version 3.7.5, 7 Feb 2007

Many bug fixes for the Server-Side functions linear_scale(), grid(),
geogrid() and geoarray().

Added dump method to the BaseType classes, DAS, DDS, DataDDS. To do
this, created a DapObj base class for all of these to inherit from
(directly or indirectly) and in the DapObj class is the operator<<
method. This will aid in debugging. Created an indentation classes to
help with dumping objects.

Win32 port fixes. The Win32 build is closer to the Unix build. Our
hope is to get the two to be almost identical so that we can all build
on Win32 and thus get away from having the win32 releases lag behind the
Unix releases.

Fix in Vector for gcc 4.1

News for version 3.7.4, 02 Jan 2007

Build enhancements and bug fixes. See ChangeLog for specifics.

News for version 3.7.3, 24 Nov 2006

Fixed unescattr() so that it works!

Rob added improvements to the win32 build.

Fixed a number of bugs including: Problems with the DDS::transfer_attributes()
method which broke libnc-dap; Added a new configuration parameter to .dodsrc
so that SSL validation can be suppressed; Fixed problems with the change from
\n to \r\n line terminators for MIME headers which slipped through the cracks
the first time; and add gzip and compress to the set of accepted compression
types supported by the client side.

Added Connect::request_ddx() which asks a server for the DDX response. 
Previously, it was possible to use getdap to print the DDX, but that object
was actually built using the DAS and DDS from a server. Now the server is asked
for the DDX. Servers should support this response to be compliant with DAP 3.1.

In the ConstraintEvaluator class, the add_function() method now allows a server
to override a function from libdap with a new definition of the same name.

I added a new interface for the scalar types: value() and set_value() can be
used to get and set values. These are much simple to use than the older
val2buf() and buf2val() methods. This idea was copied from copied from the 
PassiveByte, ..., classes.

New server-side functions for geographical constraints have been added. These
functions provide a way to select parts of Grid or Array variables using
Latitude and Longitude. Also added is a version() function which can be used
by clients to figure out which version of functions is present. The version
function has two forms, one which returns the information as plain text and
one which returns the information in a small XML document. libdap 3.7.3 is a
beta release of these functions. Note that these are _server-side_ functions
so before they can be used, servers need to be built using this library and
installed.

The dap-config script has been fixed so that it behaves more like other 
such scripts.

News for version 3.7.2

Fixed a persistent bug in the GNURegex code. (ticket 389)

Fixed a problem in HTTPConnect where the change from newline to cr/nl line
terminators was not accommodated (no ticket, but part of the issues behind
ticket 552).

Added Sequence::transfer_data(). This method uses the read() method to read
data and follows the same logic used by serialize to determine which data is
'sent' but instead records the data in the d_values field. Thus a Sequence
can transfer data to itself. The locally stored data apes the ability of the
other classes to store a complete response and is the basis for the new ASCII
response code (in dap-server/asciival) which Server4 uses.

There's a fair amount of the geogrid() code now in place, although the
function does not work, I have added a GeoConstraint class which is close to
complete. The CEFunctionsTest unit tests fail.

News for version 3.7.1

Fixed bug #480. Attributes from the HDF4 server were not being handled in a
way that made sense to netCDF clients.

Added a new method to AttrTable so that a vector of strings can be used to
set a vector of attribute values in one call. No more need to build a loop
every time you want to set values.

The grid() CE function now conforms to the design submitted to URI as part of
the REASoN award.

Fixed a bug when % signs were not handled correctly by the code in
escaping.cc. 

News for version 3.7.0

The big change: The first of the DAP3/4 features was added to the libdap
library; the library now includes the DAP protocol version number in all
responses. A savvy client can test for this and process accordingly. 

A second feature, representation of the data source metadata in XML, is
supported in alpha form. Expect the 'DDX' response to change slightly in the
next release. The DDX returned now contains an obsolete element named 'Blob'
which we won't be using. Other than the Blob element, the current DDX
probably will not change much except for the addition of new datatypes,
something that will take place only after other changes are made to the
protocol. Many of the handlers now support returning the DDX, so developers
can begin to play with it's capabilities. 

What's really nice about the DDX: It's cool that the DDX now encode the
metadata in XML, but the really nice feature is that it combines information
from the DDS and DAS, making the association of attributes to variables much
easier. 

Updated the reference guide (HTML pages in docs).

Fixed a pernicious bug in GNURegex.cc

Added the class ConstraintEvaluator. The DDS class now takes the constraint
evaluator as a parameter, so it's possible to replace ours with your own.

The single library libdap has been split into three libraries: libdap for the 
DAP functionality, libdapclient for the client-side classes and libdapserver
for the server-side classes.

Added INSTALL.AIX which contains information about building libdap on AIX
using the _native compiler_. 

News for version 3.6.2

This version includes two bug fixes. 

1. The library can now correctly reads binary data objects saved using the web
interface. Before, this was very hard to do. The utility getdap has been
modified so that it can decode these saved '.dods' files.

2. The DODSFilter class used to build all of our data handlers no longer 
blocks when returning a data object to a web browser. This fixes a problem
where the 'Get Binary' button on the data server's web interface would hang
seemingly forever. In fact it did return the data blob, but only after the 
blocked handler had timed out.

News for version 3.6.1

Fixed a bug in deflate.c: Some comments used the C++ style comments and gcc
rejected that.

Data server filters built with the 3.6.0 library were not compatible with the
dap-server 3.6.0 software because the DODSFilter class did not recognize the
-t option (which is used to pass the handler a timeout value).

News for version 3.6.0

Added patches for RPM spec files from Patrice Dumas.

Fixed a problem where Grids with two or more dimensions with the same name 
were flagged as broken (by Grid::check_semantics). Now they are allowed as per
the specification.

Added a new method get_parent() to AttrTable. This returns the parent 
container for this AttrTable.

I removed the old iostream methods from the library. These methods should not
be used because in many cases since other parts of the library use the C/stdio 
functions for I/O. In older versions of gcc, it was possible to mix the
two types of I/O systems, but not now (and not in other compilers). To change
your code, look in the file Removed_functions.txt to see the functions/methods
that have been removed. In all cases there is a version that takes a FILE *
in place of the ostream &. Use the FILE* version. If you're performing I/O
that relies on operator<<() to do type conversions, use an ostringstream 
in your code and then write the string to stdout (or wherever) using fprintf
like: fprintf(stdout, "%s", oss.str().c_str()). Ugly, but easier in some
cases than replacing lots of tested C++ I/O with fprintf calls.

I removed old methods in Connect that have been deprecated for more than
a year. See Removed_functions.txt

I removed the old Pix methods. See removed_functions.txt.

I removed the const char * overloads added to prevent collisions between
the Pix and String (not string, but GNU's old libg String class) methods.

Added protocol version number header to responses which use the set_mime...()
functions. The new header is called "XDAP-Protocol" and its value is the 
two digit DAP protocol version number. This is now used by the client-side
deserialize() methods; I assume that a server that does not announce its
protocol version is a 2.0 server.

Removed the set_mime...() functions which take an iostream; use the ones 
which take the FILE* instead. We replaced the iostream versions with FILE*
versions a long time ago because the parsers all use FILE* I/O functions
and mixing the C++ and C I/O is not predictable. The old functions were
deprecated. To fix your code, just change the iostream variable to a FILE*.
In most cases this will mean changing 'cout' to 'stdout.' 

News for Release 3.5.3

Changes to the Regex software. I've reimplemented the GNURegex code to 
use the only the POSIX functions. Because of this there are some subtle
changes in the way the class Regex works. These changes address bugs that
show up on Mac OS/X 10.4 (Tiger).

1) Meta characters like '{' now have to be escaped like '\\{'
2) See the docs for the Regex::match and Regex::serach methods. Regex:match 
   returns the number of characters that match or -1 if there's no match.
   Regex::serach returns the position of the _first_ match (not the longest
   as with POSIX) and the length of that first match in the value-result
   parameter 'matchlen'.
3) The Regex constructor now takes only one argument, the regular expression
   to compile. There's a second ctor that takes a second parameter (an int)
   but it is a dummy.
   
As a result of these changes, a small portion of the interface for libdap
has changed.
   
Build improvements from Patrice Dumas.

Added a Mac OS/X package and RedHat rpm/srpm targets. There's also a pmsp
file for use with Mac's PackageMaker.

News for Release 3.5.2

Fixed a bug where malformed Error objects from servers caused an exception.
This caused the original error message to be lost, not very helpful.

The library used a compile-time switch to control use of the factory class for
creation of objects at run-time. This was causing more trouble than it was
preventing, so I removed it. Code should switch from the 'virtual
constructors' to the factory class now.

The Test classes in the subdir 'test' should now produce the same values on
64- and 32-bit machines.

Unit tests should all work (although one of the tests for util.cc is known to
fail on FC4).

Revamped the build to use automake. 

Regression tests and the test classes are now in the subdir 'tests.'

The unit tests are now in the subdir 'unit-tests' and are not built or run by
default. Some of these tests require access to the Internet to work and I
decided to make then not run using the make check target from the top level
(the regression tests in 'tests' do run using the top-level check target) so
that the build would work w/o access to the net.

The rpm spec file has been updated. See INSTALL for information about
building rpm distributions.

Thanks to Patrice Dumas for help on the autoconf/make, with gnulib and the
rpm spec file.

News for Release 3.5.1 beta 2005/05/13

I changed some of the build parameters; the utility script is now named
dap-config, the headers now install into $prefix/include/dap and the static
library no longer has a version number appended. I've also written a rpm spec
file which can be used to build a rpm file of/for a binary distribution. At
this stage you'll need to be pretty savvy with RPM to get it to work; I'll
write up instructions soon.

News for Release 3.5.0 beta 2005/05/05

Changes in the way the software is organized:

* First, the old 'DODS' CVS module is being broken up to facilitate more
  frequent releases of software. libdap++ has a new CVS module named
  'libdap.' To access the software using CVS, use 'cvs co libdap' (where in
  the past you used 'cvs co DODS/src/dap' or 'cvs co DODS' and then changed
  into the DODS/src/dap directory).

* The autoconf scripts have been updated; still no libtool or Makefile.am,
  but the scripts are much more robust.

* The third-party packages are no longer bundled with the library. In a sense
  they never were, but they _were_ a part of the DODS CVS module. Now it's up
  to you to get and install the required packages. Look on the web site (or
  Google) for libxml2 and curl. We build using curl version 7.12.3 and libxml
  version 2.6.16; curl 7.12.0 and libxml2 2.5.7 should work.

* The libdap software now installs in $prefix/{lib,include,bin} instead of
  inside the 'DODS tree.' By default $prefix is /usr/local; use the --prefix
  option of configure to specify a different directory than /usr/local. The
  library itself installs in $prefix/lib as libdap++.a.3.5; libdap++.a is
  symbolically linked to that file. The header files now install in
  $prefix/include/libdap-3.5; $prefix/include/libdap is symbolically linked
  to that directory. The utilities geturl and opendap-config have been
  renamed getdap and dap-config, respectively (the name geturl corresponds to
  another utility). The getdap utility is, except for the name change,
  exactly the same as geturl. The dap-config script provides a way to
  determine which libraries should be included when linking with a particular
  build of libdap++. It also provides information about the version of the
  library linked to $prefix/lib/libdap++.a and some other stuff. Use
  dap-config --help for a listing of all the options. Finally, the deflate
  program, which is used by some servers to provide compressed responses and
  is called by the library is not stored in $prefix/sbin (except on win32
  where it's stored in $prefix/bin).

  The usage program is not currently installed; once we complete the
  reorganization process it will find a good home.

Other changes to libdap++:

* The library now uses a factory class to determine how to instantiate
  specializations of Byte, Int32, et cetera. The class BaseTypeFactory
  defines the interface for the factory and provides a default implementation
  of the class. This implementation instantiates Byte, ..., Grid. Also
  supplied with the library is TestTypeFactory which instantiates the Test
  type classes (TestByte, ..., TestGrid). If your use of the library requires
  that the type classes be specialized, then you must modify your software so
  that it includes a factory class that specializes BaseTypeFactory. Then,
  when you create a DDS (or DataDDS) pass a pointer to an instance of your
  factory to the DDS constructor (or use the new DDS::set_factory() method).
  Look at BaseTypeFactory and the example specialization TestTypeFactory.
  It's very straightforward to make the change.

  For applications which don't specialize the type classes, the default
  factory should be fine. To avoid using the new DDS constructor (which
  requires that a pointer to an instance of BaseTypeFactory be supplied), your
  code must #define the symbol DEFAULT_BASETYPE_FACTORY. If this symbol is
  not defined (at compile time) then various compile-time errors will occur
  (the idea being this will prevent software from building and silently
  ignoring specializations of the type classes). If defined, this use the
  default factory class.

  The documentation for the DDS constructor has some more information.

* The library contains support for the DDX object. The DDX will become the
  foundation of the DAP3 protocol. It uses XML to describe the information
  currently represented using our 'curly-brace' notation and also bundles
  the attributes along with the variables they describe. This will simplify
  many processing tasks for clients. The software provided simplifies
  generating the DDX by building it from existing DAS and DDS objects.

* There has also been some significant re-factoring in DDS and DAS: The
  DDS:send() method has been copied over to DODSFilter and the version in DDS
  has been deprecated and will be removed in a future version of the library.
  The library uses STL iterators almost exclusively and the next version will
  eliminate the ancient Pix class.

* The function dods_root() is now called libdap_root() and tests the
  environment variable LIBDAP_ROOT. If that variable is not set,
  libdap_root() returns the value passed to the --prefix option of configure
  or /usr/local if the option was not used. Added to libdap++ is a function
  libdap_version() which returns the version number of the library. Note that
  libdap_version() is declared as extern "C" so that it can be used in
  configure tests to check for the library.

* The servers no longer provide three programs to handle the das, dds and
  data requests. Instead one *_handler is provided. This reduces the size of
  the servers by a factor of three and paves the way toward integration of
  the HTML and ASCII code into the server binary, which will improve the
  performance and security of those features.
