Greetings,<br><br>I have a question about setting up an external data source. My case should be fairly simple - The external data source&#39;s URL requires no parameters, and when the data is returned, it&#39;s just a URL directly to a file. Example:<br>

<span style="font-family: courier new,monospace;"><a href="http://myserver/data_search_page.html">http://myserver/data_search_page.html</a></span><br>returns...<br><span style="font-family: courier new,monospace;"><a href="http://myserver/repository/the_file.bed">http://myserver/repository/the_file.bed</a></span><br>

<br>I&#39;ve looked at multiple examples of the XML files &amp; the wiki, and I think I&#39;ve got it. However there&#39;s one part I&#39;m still unclear about - the &lt;param&gt; tag inside the &lt;inputs&gt; tag. Examples:<br>

<span style="font-family: courier new,monospace;">&lt;param name=&quot;GALAXY_URL&quot; type=&quot;baseurl&quot; value=&quot;/tool_runner/biomart&quot; /&gt;</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">&lt;param name=&quot;GALAXY_URL&quot; type=&quot;baseurl&quot; value=&quot;/tool_runner&quot; /&gt;</span><br style="font-family: courier new,monospace;">

<span style="font-family: courier new,monospace;">&lt;param name=&quot;GALAXY_URL&quot; type=&quot;baseurl&quot; value=&quot;/tool_runner?tool_id=flymine&quot; /&gt;</span><br><br>It seems that the &quot;value&quot; string gets appended onto the GALAXY_URL (which would then be returned to Galaxy). Could you please explain what&#39;s happening here?  Do I need to write a separate tool which would be executed by &#39;tool_runner&#39;?<br>

I thought &quot;data_source.py&quot; *was* the tool, no?<br><br>Thanks very much for your help,<br>Chris Zaleski<br>Gingeras Lab - CSHL<br>