Announcement ... SQLClient 1.1 for GNUstep

[Richard Frith-Macdonald]

A new, stable release of SQLClient is now available.

New since the initial release -

Some bugfixes after a lot of testing and real life use of the postgres 
backend bundle.
Ported to MacOS-X (with gnustep-base).
Efficient and powerful methods for managing transactions.
WebServer class (may be moved out to another package later) for rapid, 
lightweight web server development.


What is the SQLClient library?

The SQLClient library is designed to provide a simple interface to SQL
databases for GNUstep applications. It does not attempt the sort of
abstraction provided by the much more sophisticated GDL2 library
but rather allows applications to directly execute SQL queries and 
statements.

SQLClient provides for the Objective-C programmer much the same thing 
that
JDBC provides for the Java programmer (though SQLClient is a bit faster,
easier to use, and easier to add new database backends for than JDBC).

The major features of the SQLClient library are -

    * Simple API for executing queries and statements...
      a variable length sequence of comma separated strings and other
      objects (NSNumber, NSDate, NSData) are concatenated into a single
      SQL statement and executed.
    * Simple API for combining multiple SQL statements into a single
      transaction which can be used to minimise client-server 
interactions
      to get the best possible performance from your database.
    * Supports multiple sumultaneous named connections to a database 
server
      in a thread-safe manner.
    * Supports multiple simultaneous connections to different database
      servers with backend driver bundles loaded for different database
      engines. Clear, simple subclassing of the abstract base class to
      enable easy implementation of new backend bundles.
    * Configuration for all connections held in one place and referenced
      by connection name for ease of configuration control. Changes via
      NSUserDefaults can even allow reconfiguration of client instances
      within a running application.
    * Thread safe operation... The base class supports locking such that
      a single instance can be shared between multiple threads.

What backend bundles are available?

Current backend bundles are -

    * ECPG - a bundle using the embedded SQL interface for postgres.
      This is based on a similar code which has been in production
      use for over eighteen months, so it should be reliable.

    * Postgres - a bundle using the libpq native interface for postgres.
      This is the preferred backend as it allows 'SELECT FOR UPDATE',
      which the ECPG backend cannot support due to limitations in the
      postgres implementation of cursors. Now well tested efficient,
      and in use in large commercial systems.

    * MySQL - a bundle using the mysqlclient library for *recent* MySQL.
      I don't use MySQL... but the test program ran successfully with a
      vanilla install of the MySQL packages for recent Debian unstable.

    * Oracle - a bundle using embedded SQL for Oracle.
      Completely untested... may even need some work to compile...
      but this *is* based on code which was working about a year ago.
      No support for BLOBs yet.

Where can you get it? How can you install it?

The SQLClient library is currently only available via CVS from the 
GNUstep CVS repository.
See <https://savannah.gnu.org/cvs/?group=gnustep>
You need to check out gnustep/dev-libs/SQLClient

To build this library you must have a basic GNUstep environment set 
up...

    * The gnustep-make package must have been built and installed.
    * The gnustep-base package must have been built and installed.
    * You must hace sourced the GNUstep.sh script (from gnustep-make)
      to set up environment variables needed for building this.
    * If this environment is in place, all you should need to do is
      run 'make' to configure and build the library, 'make install'
      to install it.
    * Then you can run the test programs.
    * Your most likely problems are that the configure script may
      not detect the database libraries you want... Please figure
      out how to modify configure.ac so that it will detect the
      required headers and libraries on your system, and supply a patch.

Bug reports, patches, and contributions (eg a backend bundle for a new 
database)
should be entered on the GNUstep project page
<http://savannah.gnu.org/support/?group-gnustep>



The WebServer class provides the framework for a GNUstep program to act 
as
an HTTP or HTTPS server for simple applications.
It does not attempt to be a general-purpose web server, but is rather
intended to permit a program to easily handle requests from automated
systems which are intended to control, monitor, or use the services
provided by the program in which the class is embedded.
The emphasis is on making it robust/reliable/simple, so you can rapidly
develop software using it. It is a single-threaded, single-process
system using asynchronous I/O, so you can easily run it under debug
in gdb to fix any bugs in your delegate object.
In particular of course, it may be used in conjunction with the
SQLClient class to implement web-based database applications.

The class is controlled by a few straightforward settings and basically
operates by handing over requests to its delegate. The delegate must at
least implement the -processRequest:response:for: method.

Built-in facilities include -

* Parsing of parameter string in request URL
* Parsing of url encoded form data in a POST request
* Parsing of form encoded data in a POST request
* Substitution into template pages on output
* SSL support
* Limit access by IP address
* Limit total number of simultaneous connections
* Limit number of simultaneous connectionsform one address
* Limit idle time permitted on a connection
* Limit size of request headers permitted
* Limit size of request body permitted