OpenCms URLs

The URL retrieval mechanism in OpenCms can be confusing to new users. When processing a request, OpenCms translates the requested URL to a VFS resource path before delivering the file.

The cause for misunderstanding and trouble is that translation pays attention to the current site of the request. When logged into the workspace the site can be changed with the Site select box at the top of the window. The current site of external requests (from outside the workspace) is determined automatically from the request URL.

Formal URL Syntax

The formal syntax of OpenCms URLs can be written as follows:

OpenCmsUrl ::=    Site ServletPath RequestPath
Site ::=          Protocol "://" Host ":" {Port}
ServletPath ::=   "/" WebappName "/opencms"
RequestPath ::=   SystemPath | ResourcePath
SystemPath ::=    "/system/" ResourcePath
ResourcePath ::=  "/" { [PathCharacter]+ "/"? }*
PathCharacter ::= A valid file or directory name character

Example

Consider a request for the following URL (on a OpenCms default installation):

http://localhost:8080/opencms/opencms/sites/default/index.jsp

opencms-system.xml:

<sites>
  <workplace-server>http://localhost:8080</workplace-server>
  <default-uri>/sites/default</default-uri>
  <site server="http://localhost:8080" uri="/sites/default"/>
</sites>

The above URL is parsed into the following elements:

Site: http://localhost:8080
ServletPath: /opencms/opencms
RequestPath: /sites/default/index.jsp

The Site is matched against the servers defined in opencms-system.xml. The matching site is selected as the current site to serve the request.

In order to finally determine the VFS resource path of the requested file OpenCms adds the uri attribute of the current site in front of the RequestPath unless it is equal to the current site of the browser session.

The effects of URL translation

If this URL is called from the Explorer by clicking on the _index.jsp_ file in /sites/default, the VFS resource path will be /sites/default/index.jsp.

However, if the same URL is called from a browser not logged in to the OpenCms workplace, the constructed VFS resource path will be /sites/default/sites/default/index.jsp. The request will end with HTTP 404. The reason for this that /sites/default is the URL configured for the site localhost in opencms-system.xml. The SitePath may not occur in URLs accessed from outside of the workplace.

The correct external URL for the file /sites/default/index.jsp therefore is http://localhost:8080/opencms/opencms/index.jsp.