$Id: release-3.4.txt,v 1.4 2003/06/20 02:29:26 tom Exp $


OPeNDAP/DODS C++ 3.4 Release Candidate 1 (Beta) is now available.

Release candidates are not considered stable releases. Please treat it
accordingly (e.g., not installing as your operational system, expect
some bugs and report any you find). Here is what's new in the
OPeNDAP/DODS C++ core version 3.4:

Code changes
   1.  Libcurl instead of libwww.
   2.  URL dereferencing done with curl instead of Perl.
   3.  C++ DAP is now thread-safe.
   4.  New interface for DAS and DDS classes.
   5.  Core compiles with gcc 3.2.1, Visual C++ 6.0 and gcc 2.95.
   6.  Bug fixes

Client usage changes
   7.  Passwords can be included in URLs.

Server usage changes
   8.  dods.rc
   9.  statistics

New software
   10. OPeNDAP AIS prototype is available
   11. netCDF client and server upgraded
   12. DODSter module added to emulate the MODster software.


CODE CHANGES

 1. The DODS core now links to libcurl instead of libwww for WWW
    functions.  The libcurl library is smaller than libwww, and is
    being actively developed.

 2. The server dispatch scripts no longer use the Perl HTTP, MIME and
    LWP classes.  Instead, URL dereferencing is done with curl, a
    freestanding binary that is part of the libcurl build.

 3. The core software is now multi-thread safe. 

 4. The interface to several important classes has been augmented.
    The DAS and DDS classes have a new set of interfaces so that STL
    iterators can be used to manipulate their contents.  The Old Pix
    interfaces are still present, although uses of Pix that rely on
    those objects being void pointers may fail in certain
    circumstances.

    To write out the names of all the variables in a DDS, you would use 
    Pix code like this:

       for (Pix p = dds.first_var(); p; dds.next_var(p)) {
           cout << dds.var(p)->name() << endl;
       }

    Using the STL for the same purpose, you would do this:

       for (DDS::Vars_iter i = dds.begin_var(); 1 != dds.end_var(); ++i) {
           cout << (*i)->name() << endl;
       }

    There have also been some additions to the DAS, DDS and AttrTable
    that make it easier for non-C++ programs to traverse those
    containers.

    For example, in the DDS class, we have the new method:

       Vars_iter get_vars_iter(int i);

    In AttrTable we have:

       Attr_iter get_attr_iter(int i);

    Both of these make it possible to access members of the DDS and
    DAS containers from C code using a simple integer index. This is
    important because C programs cannot create the fancy STL iterator
    objects.  (They can fake a Pix pointer, but this leads to problems
    and should not be done.)

 5. The C++ DAP now builds with gcc 3.2.1, in addition to gcc 2.95 and
    Visual C++ 6.0.  These are the compiler versions that have been
    tested.  Other versions may also work.  Other compilers may also
    work as long as they support the STL (Standard Template Library).

 6. Server bug fixes have included fixes to Sequence constraint
    behavior, the Grid constraint expression function, and memory
    leaks.

    The grid() server-side function is now part of all servers.
    Suppose you have a Grid variable SST that looks like:

       Grid {
         Array:
           Byte SST[lat=1024][lon=1024];
         Maps:
           Float64 lat[1024];
	   Float64 lon[1024];
       } SST;

    You can use the following constraints:

       ?grid(SST,"lat>10.0","lat<20.0")

    Returns the part where "lat" is between 10.0 and 20.0.  All the
    "lon" values are returned.

       ?grid(SST,"10.0<lat<20.0")

    This does the same thing, with a simpler syntax.
 
       ?grid(SST,"10.0<lat<20.0","-80.0<lon<-30.0")

    This returns the part of the Grid falling in the specified
    latitude/longitude box.

    The grid() function operates under the following restrictions: The
    map vectors must be monotonic for the selected Grid.  The quoted
    expressions must contain only the names of map vectors of the
    Grid, constants and relational operators. 

    Note: This is not a geoselection function.  Map vectors may be
      composed of any of the simple DAP types.  (Like strings, for
      example.) 


CLIENT USAGE CHANGES

 7. The DODS core now supports the (nonstandard) password-in-URL
    syntax.  If you are accessing a password-protected data set, you
    can include your user name and password directly in the URL like
    so: 

      http://user:password@dods.org/cgi-bin/nph-nc/data.nc

    Including a password in the URL allows the user to avoid the extra
    overhead of the authentication dialog box that was the only option
    in earlier releases.

SERVER USAGE CHANGES

 8. The name of the server configuration file has been changed from
    dods.ini to dods.rc.

 9. A new feature of the servers allows the DODS project to gather
    access statistics from sites who choose to allow it.  During the
    installation process (via the installServer script), the server
    administrator is asked for permission to gather this data.  If
    permission is granted, the server will return DODS access data (no
    other data is provided) to queries that emanate from one of the
    official DODS web sites.  The statistics feature refers only to
    DODS server accesses, not to any accesses of other web content.

    Note: The DODS project understands that allowing access to the
      DODS/DAP server's usage information might not be acceptable to
      some server administrators. However, allowing us access to the
      server's usage information will help us direct future software
      development efforts. If you choose to enable this feature, only
      the local host and official DODS/OPeNDAP machines will be able
      to gain access to the statistical information.

NEW SOFTWARE

10. A very early prototype Attribute Information Server (AIS) is
    available.  This version is for concept testing, and is likely to
    contain bugs and need substantial improvement.  However, the DODS
    project also needs people to contribute feedback to its
    development, so it is being made available for that purpose.
    Contact the project if you're interested in testing this software.


11. The DODS-enabled netCDF client library and servers have been
    upgraded to be compatible with netCDF 3.5. The netCDF client
    library now use a DODS error object to send the netCDF 3.5 system
    error codes to the client. The client library reports errors
    received from the servers in addition to DODS internal and local
    error codes. Also invalid_error messages due to handling error
    exception are fixed.

12. DODSster capabilities have been added to the server software.
    DODSster is an experimental system created in a partnership with
    the Earth System Science Workbench that provides a way for DODS
    servers to use the MODster system to serve MODIS data. With
    DODSster you can use a DODS server to fetch a URL from a MODster
    site and then serve it.

    For more information, see: http://essw.bren.ucsb.edu/modster/ or
    contact jgallagher@gso.uri.edu.


$Log: release-3.4.txt,v $
Revision 1.4  2003/06/20 02:29:26  tom
made adjustments

Revision 1.3  2003/06/19 18:45:35  jimg
Added some answers.

Revision 1.2  2003/06/19 03:13:44  tom
first draft, still unanswered questions

Revision 1.1  2003/06/18 19:45:52  tom
skeleton