Embedded Web Server

Introduction

EWS is a web server construction kit, designed for embedded applications using the GNAT Ada compiler.

The project is hosted on Github.

Building with Alire

After you've installed Alire, start a small test program by saying

alr init --bin ews_test
cd ews_test
alr with ews

This generates a project (GPR) file at the top level and a source file src/ews_test.adb.

Create a directory html and in it index.html containing (for example)

<html>
<body>
<font color="red">Hello world!</font>
</body>
</html>

The contents of html/ need to be converted to Ada source code in src/, which will form the static content of the pages served by ews_test. This can be done as part of the Alire build process; to do this, edit alire.toml to add the lines

[[actions]]
type = "pre-build"
command = ["ews_generator", "--input-dir", "html", "--output-dir", "src"]

Edit the contents of src/ews_test.adb to contain

with EWS_Htdocs;
with EWS.Server;
procedure EWS_Test is
begin
   EWS.Server.Serve (Using_Port => 8088,
                     Tracing    => True);
end EWS_Test;

and build and run with

alr run

Now, in your browser, open localhost:8088 (possibly, 127.0.0.1:8088) to see your exciting web page!

To see a worked example of dynamic content, check out the document ews.pdf.

Building outside Alire

EWS requires GNAT and XML/Ada, and uses Ada 2012 features.

In the top-level directory, make will build the library, and make demo will create a server doc/ews_demo, which when executed will listen on port 8080 and respond with the web in the doc/ directory.

The package can be installed with the compiler by make install (more likely, sudo make install). You can install in an alternative place by setting prefix, for example

$ make install prefix=~/local/ews

Dynamic web

The facilities available in EWS, and the code for a demonstration, are described in demonstrator/ews.pdf, which is derived from demonstrator/ews.w. As well as being the document source, ews.w also acts as the source code using the Literate Programming facilities of nuweb.py.

Demonstration

If you're seeing this page via the demonstration (ews_demo), you can view a page with AJAX content here.