Java agent to get an rss feed behind a proxy server

I just finished developing the integration of this blog in our company website (under ‘Portfolio’ on the right).

This site is running on domino. This is how I accomplished this:

1. Create a java agent to read the rss feed.
2. On the web page, use an XmlHttpRequest to call the agent and get the XML.
3. Also in javascript: parse the XML to HTML and put in a div on the website.

The code for step 2 and 3, you can see on our website: just download the javascript code (we use dojo as a framework).

Step 1 is also fairly simple. Here is the most important part of the code:

Session session = getSession();
AgentContext agentContext = session.getAgentContext();
PrintWriter pw = getAgentOutput();
pw.println("Content-type: text/xml; charset=utf-8");
URL labs = new URL("http://labs.groupwave.be/index.php/feed/");
BufferedReader in = new BufferedReader(new InputStreamReader(labs.openStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
pw.println(inputLine);
in.close();

The tricky part for me was the get past our proxy server. I was testing this code on my local domino server meaning that the proxy server had to be used to access the internet (and the feed). I tried modifying the server document and setting the agent security to allow unrestricted operations. To no avail.

Then I found out that the java.policy file (in the ‘jvm/lib/security’ folder) has to be modified to allow java to modify system settings. And that’s what’s needed to set up the proxy server in java:

java.util.Properties sysProps = System.getProperties();
sysProps.put("proxySet", "true");
sysProps.put("proxyHost", "proxy.iconos.be");
sysProps.put("proxyPort", "8080");

This is what you need to add in the java.policy file to get this to work (in the ‘grant’ section – “default permissions granted to all domains”):

permission java.security.AllPermission
permission java.util.PropertyPermission "proxySet", "write";
permission java.util.PropertyPermission "proxyHost", "write";
permission java.util.PropertyPermission "proxyPort", "write";

Hope this helps some of you…

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