I was somewhat concerned about the disorderly proliferation of servlets
designed to provide information about internal node status, and wanted to
create a better thought-out structure into which code designed to give
status information could be placed.
To address this problem, I have created a new Servlet called the
freenet.client.http.NodeInfoServlet, with which implementations of the
freenet.client.http.Infolet interface can register. To enable this, get
current CVS or tomorrow's snapshot, and add:
nodeinfo.class=freenet.client.http.NodeInfoServlet
nodeinfo.port=8890
To your config file. If you visit it you won't see much, just a somewhat
ugly page with a menu down the left (with a test infolet), and some text
(anyone who wants to improve the HTML should take a look at the
NodeInfoServlet class - it is *very* ugly right now). Each Infolet should
provide information on one aspect of Freenet's operation, and the should
be split into groups.
Creating a new Infolet is simplicity itself, take a look at the classes in
the freenet.client.http.infolets package for some simple examples. Just
implement the freenet.client.http.Infolet interface and fill out the two
simple methods in it (one initialises the Infolet with the node's
freenet.node.Node object, the other grabs the Infolet's output for
inclusion in a page. The output should be a HTML fragment (ie. the stuff
that goes between the <body> tags).
The infolet must then be hardwired into the NodeInfoServlet, take a look
at its init() method, it is really straight-forward - here is the comment
that explains it:
Create the group, register it, and then register the
Infolets which are to be part of that group in the order you
want to see them in the menu. The long group name should be
the name which will appear in the menu, the short group name
will be the name that will appear in the URL (so it should
basically be nothing but lower-case alphanumeric characters).
The same is true for the long and short names of the Infolets
themselves.
For example:
Group testGroup = new Group("Long Group Name", "briefgroupname");
registerGroup(testGroup);
registerInfolet(testGroup, new TestInfolet());
registerInfolet(testGroup, new TestInfolet2());
...
Group testGroup2 = new Group("Second Long Group Name",
"briefgroupname2");
...
As can be seen, I have created a new package to contain the infolets
(freenet.client.http.infolets), but they don't have to go in there if you
have a good reason to put them somewhere else.
People will notice that Infolets are much more constrained in the
information they have access to, and the way they can respond to it, than
Servlets. This is deliberate, Infolets shouldn't modify the Node in any
way, they are purely for giving the status of a particular aspect of node
operation, although if there are specific pieces of functionality that
people really want Infolets to have (such as getting access to the GET
parameters) we could do that (this might be nescessary, for example, to
allow Oskar's Diagnostics stuff to be converted to an Infolet).
I would invite the authors of existing node status servlets to convert
them to Infolets, if there is any functionality you *really* need that is
currently lacking, either let me know, or add it yourself.
Thoughts, comments, insults?
Ian.
--
Ian Clarke ian at freenetproject.org
Founder & Coordinator, The Freenet Project http://freenetproject.org/
Chief Technology Officer, Uprizer Inc. http://www.uprizer.com/
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