A W S - Ada Web Server
Pascal Obry October 29th, 2001,
Dmitriy Anisimkov and I are very happy to announce the availability of the
AWS 1.1 release. The API could change slightly at this stage but should be
fairly stable now.
AWS stand for Ada Web Server. It is not a real Web Server like Apache. It is
a small yet powerful HTTP component to embedded in any applications. It means
that you can communicate with your application using a standard Web browser
and this without the need for a Web Server. AWS is fully developed in Ada with
Here are the main changes:
- Server push implementation. Tested only with Netscape Navigator.
- SOAP - beta implementation of SOAP. Support all SOAP types. This
implementation has been validated through http://validator.soapware.org/
and therefore should be quite inter-operable with other SOAP
implementation. This implementation covers the SOAP client interface and
as all supports to build SOAP servers.
Versions that validate on http://validator.soapware.org/ are the AWS
version string (AWS.Version) catenated with the SOAP version string
- Add accept queue size parameter to help building heavy loaded servers.
- Fix the Runme NT service demo.
- Web Servers is started only if needed (during Server.Start) call and not
when declaring the HTTP objects.
- Max Connection is not anymore a discriminant. This parameter is set with
the Start routine. This change is not upward-compatible, but it is worth
it since now, it is possible to change the server configuration
dynamically. What need to be changed:
1) Removes the discriminant on each HTTP objects
2) Pass the number of maximum connections (was the discriminant) in the
This will make the server configured the very same way.
- Handle User_Agent and Referer HTTP headers.
- Add message size in the log files (last field). Now the log format is 100%
compatible with the standard ones (Apache and Internet Information Server).
- Add server start time in the status page.
- Add support for user's log.
- Properly terminate task Session.Cleaner and release associated memory. Fix
a memory leak.
- Properly wait for tasks termination before releasing memory. Fix memory
- Improves the documentation.
- Install AWS as a library (libaws.a)
- As always some minor bugs have been fixed but are not listed here. See
src/ChangeLog and SOAP/ChangeLog.
- Change the build procedure, should be easier and it is cleaner. See
- First version of the regression tests suite. This will help keeping AWS
- Add timeouts support for the AWS client interface. Because of this the
AWS.Client.Create routine has its spec changed (it was a function it is
now a procedure).
- In AWS.Client, default retry count is set to 0 (was 1 before). Now the
AWS.Client routines wont try more than once to get the data by
- Properly handle textual (text/html, text/xml...) data that is chunked
- Fix SSL support in AWS. The SSL layer should now be as reliable as the
standard socket one.
- Update distribued Win32 OpenSSL library to version 0.9.6b. Also now there
are built as DLL.
NOTE: Since we have switched to the .PNG file format we have found that
Netscape Navigator is not able to display the PNG transparent layer properly!
At this stage we feel that AWS is ready to build small to medium Web
server. AWS has been reported to work under Windows NT, Linux and FreeBSD 4.1.
With this new version you'll need at least version 0.1.11 of the Socket binding
from ENST. It has been tested and works fine with version 0.1.13 too. See
The OpenSSL libraries (optional) distributed are for Windows and GNAT
3.13. GNAT 3.12 users must build the libraries from sources or obtain another
set of pre-build libraries see pointers below.
Under UNIX you'll have to build the libraries from sources, it is quite easy
to do so. This has been tested under Linux without trouble.
See documentation for build information.
AWS User's Mailing List:
AWS Home Page (sources and documentation):
Templates_Parser module (sources and documentation) is provided with AWS
distribution. Latest version of this module and the documentation can be
Temlates_Parser is a very useful add-on for AWS. You should have a look at
it if you plan to develop a Web service. Templates_Parser permits to
completely separate the HTML design from the Ada code.
Some other Templates engine are WebMacro, FreeMarker, PHP, ASP, JSP and
Velocity. All of them are based on explicit iterators (#foreach with a
variable) where Templates_Parser is based on implicit ones (you use a more
intuitive table iterator). Be sure to check the documentation. Only
the Velocity project has the goal to support complete separation of HTML
design and code.
You need this library only if you want to use AWS SOAP feature. You need
at least XMLada 0.6.
XMLAda 0.6 has some memory leaks. This has been fixed now, so with future
version of XMLAda it will be possible to build long-lived servers.
POSIX Binding (optional) :
OpenSSL library (optional) :
Sources for UNIX or Win32:
binaries for Win32 with GNAT 3.13 (and later):
Included with the main AWS distribution.
Note that we have used and we distribute (for Win32 platform) OpenSSL
version 0.9.6b with this AWS release. OpenSSL have been built with GCC
version 2.95.2 with optimization (-O3) on.
See OpenSSL license (docs/openssl.license).
Windows Services API (optional):
To build the runme demo as a Windows NT/2000 services you must download
the services API made by Ted Dennison for his SETI@Home project.
You can report bugs to:
Dmitriy Anisimkov [log in to unmask]
Pascal Obry [log in to unmask]
It would be nice if you could also sent us a note if you are using AWS just
to know if it is used at all or not :) And if you are ok, we'll add an entry
for your project in the next section.
AWS User's Mailing List:
A good way to keep informed of AWS news and to share experience with other AWS
users is to register to the AWS dedicated mailing list. See:
- SETI@Home from Ted Dennison. AWS is used as a "plugable" GUI to retrieve
different program status.
- DOCWEBSERVER from Wiljan Derks
In our department we keep our documents in a directory tree. These documents
are all project related and have a certain naming convention to be able to
find the right document. In the past I already wrote a program that searches
though this directory and then converts the found documents into fixed html
pages. With AWS I was able to get a much nicer setup. I have now a server
that can do the following:
- browse through the projects in explorer style. The html contains info
about the document like date and title.
- one can check in documents through the web interface
- it shows our download page as I have send you in the example
- we have now all our documentation in small pieces of html as is needed
to build .chm (w2k compiled help) files. For these we use a content
file, that is also stored in the document archive.
The docwebserver gives by reading all this stuff the direct view on this
documentation. On the other hand I can run some tool and automatically
generate the .chm files.
- OESM Server (OESM=Overall Equipment Status Monitoring) from Wiljan Derks
I am working on a project now for our factories. ITEC mainly delivers
equipment for discrete semiconductor assembly. Almost all of that equipment
is now controlled by a similar Ada 95 based code with having a lot of code in
common. One of the common things, is the way we log errors and state changes
of our equipment.
The OESM Server is an application which copies all this information
continuously to its local pc by opening the proper files on the remote
equipment. That data copied is also stored in local files. The web server
component of the application can then, making use of that data, give reports
that show things like the amount of products produced in a certain period,
error paretos of equipment, mtbf, %time in production and of course many
The cool thing of course is that this information can easily be charted (I
am use kavachart) and it allows simple navigation through different groups
of equipments and different views on the equipment.
- WORM from Pascal Obry
A Web server to share bookmarks, this server was using a standard CGI
design. To keep session information we were using a GLADE partition. With
AWS the design has been really simplified, there is no need for a session
partition, there is no need to build all CGI as partitions too. GLADE is now
used only to handle distributed objects. Indeed WORM is a multi-server
system (using RACW) with a register/unregister mechanism.
Also the server seems to be fastest, there is no more CGI to spawn.
- Internet Currency Trading System at www.actforex.com by Dmitriy Anisimkov
This is a server is used to keep historical data about currency trading to
build charts of currency prices. The charts viewer part is written in Java
and loaded through AWS. This server can be reach on the Internet.
Ongoing work is done to based this development on AWS framework only and
to remove all the Java layers. It is also interesting to note that this is
an heavy loaded server, it has something like 40 to 50 requests per seconds.
Thanks to all who have reported bugs and have sent us patches.
Dmitriy & Pascal.
--| Pascal Obry Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--| "The best way to travel is by means of imagination"