Generating class status pages

As you evolve your APIs, you might want to ensure that you have not removed accidentally public API entry points, or changed their APIs if you want your users to experience a smooth upgrade to a new version of your library.

To achieve this, you can use some tools that the Mono team uses internally.

The Concept

We use a couple of tools to check API compatibility. The mono-api-info tool is used to generate an XML representation of an assembly, this is done by using reflection. The tool is run on your original and new versions of the assemblies, and then you employ the mono-api-diff tool to generate a list of differences in your libraries.

The differences can then be rendered into an DHTML page that allows the developers to browse the changes, or can be consumed by your own tools to document changes or annotate your documentation.

Using our tools

If you want to use our tools to compare your own libraries you will need to build the tools using SVN (see AnonSVN).

Once you check out the mcs module:

  • Go to mcs/tools/corcompare and type make. It will compile mono-api-info and mono-api-diff.
  • Running the following command will give you /tmp/yourassembly-v1.xml containing a list of classes, methods, etc...:
mono mono-api-info.exe /home/user/blah/yourassembly-v1.dll > /tmp/yourassembly-v1.xml
  • Run:
mono mono-api-info.exe /home/user/blah/yourassembly-v2.dll > /tmp/yourassembly-v2.xml
  • Now we want to compare the two XML files that we have and generate another one that will be used when creating the web page.
mono mono-api-diff.exe /tmp/yourassembly-v1.xml /tmp/yourassembly-v2.xml > /tmp/yourassembly-compare-v1-vs-v2.xml

When you run make in mcs/tools/corcompare, transform.exe was also compiled. This is a small program that just applies a given XSL transformation to a XML file. In the same directory, there's a mono-api.xsl containing the XSL transformation that we use.

The command:

mono transform.exe /tmp/yourassembly-compare-v1-vs-v2.xml mono-api.xsl > /tmp/v1-vs-v2.html

will create the HTML page in /tmp/v1-vs-v2.html.

The images and javascript files used by the generated HTML are also in module mono, directory mono/web/web/deploy/cm.

For these files to work, you must insert the generated HTML into a container that pulls the scripts at startup, the "cm/cormissing.js" file and reference the file cm/cormissing.css as well, like this:

   <head>
     <link rel="stylesheet" type="text/css" href="cm/cormissing.css"/>
     <script src="cm/cormissing.js"></script>
   </head>