Package com.sapportals.wcm.util.uri

Contains interfaces and classes to handle uniform resource identifiers (uri).

See:
Description

Interface Summary

IHierarchicalUri	A RFC2396 URI interface.
IRidIterator	This interface defines an iterator for a IRidList Copyright (c) SAP AG 2001-2002
IRidList	This interface defines a list of RID instances Copyright (c) SAP AG 2001-2002
IRidSet	This interface defines a set of RID instances Copyright (c) SAP AG 2001-2002
IUri	A RFC2396 URI interface.
IUriIterator	This interface defines an iterator for a IUriList Copyright (c) SAP AG 2001-2002
IUriList	This interface defines a list of URI instances Copyright (c) SAP AG 2001-2002
IUriReference	A RFC2396 URI reference interface.

Class Summary

DataUri	A RFC2397 IUri implementation.
GenericUri	A RFC2396 IUri implementation.
HttpUrl	An IHierarchicalUri implementation for HTTP/HTTPS URLs.
OpaqueLockTokenUri	A RFC2518 IUri implementation.
ResourceUrl	An IHierarchicalUri implementation for Resource (Repository Framework internal) URLs.
RID	A RID is an identifier for a CM resource.
RidIterator	An RID iterator implementation Copyright (c) SAP AG 2001-2002
RidList	An URL list implementation Copyright (c) SAP AG 2001-2004
RidReference
RidSet	A set of RID instances.
URI	Deprecated. as of EP 5.0 SP3, replaced by RID
URICodec	Utility class for decoding/encoding URIs in HTTP requests.
UriFactory	A factory producing IUris from various inputs.
UriIterator	An URI iterator implementation Copyright (c) SAP AG 2001-2002
UriList	An URL list implementation Copyright (c) SAP AG 2001-2002
UriQuery	Manages query parameters for RFC 2396 URIs.
UriQuery.Parameter	Keeps one query parameter.
UriReference	A RFC2396 reference implementation.
URL	DO NOT USE this class except to create instances of URL objects to be used for link creation.

Package com.sapportals.wcm.util.uri Description

Contains interfaces and classes to handle uniform resource identifiers (uri).

Package Specification

The uri package handles the two worlds of RFC 2396 uris and WCM uris and how they interact.

RFC 2396 Uris

Internet Uris are defined in RFC 2396 - Uniform Resource Identifiers (URI): Generic Syntax. This RFC defines the following terms which are explained here for quick reference:

• uri: is a string of characters used as identifier for a resource. RFC 2396 defines how such a string can be composed, broken into components and combined again. The most important concept is that each uri has a scheme. The scheme of an uri defines how the rest of the uri is to be interpreted.
  Example: mailto:info@sapportals.com
• hierarchical uri: is a special kind of uri which has hierarchical components following the scheme. Basically the uri resembles a file system path, separating individual components with a slash character. The hierarchical component is often named path. The path often consists of a network component, e.g. host name and port, and an absolute path component, starting with '/'. "http" is probably the best known uri scheme which is hierarchical. Thus, a http uri is a hierarchical uri.
  Example: http://sapportals.com/news
• uri reference: Is a reference to a resource or even to a certain part of a resource. A reference is given inside one document (e.g. a HTML page) to identify (point to) another resource. A reference uri can have a postfix, starting with the '#' character, which identifies a certain part of a resource. This postfix is known as a fragment identifier. The fragment identifier can be missing in a uri reference. Only uri references have fragment identifiers. The uri always identifies the complete resource. Example: ../index/c.html#17
• absolute uri reference: This is the simplest form of an uri reference. It consists of an uri with an optional fragment identifier. An absolute uri reference stands for itself. There is no context needed to interpret it.
  Example: http://sapportals.com/news#top
• relative uri reference: are incomplete uris with an optional fragment identifier. Often the scheme and the network path are missing. Relative uri references need a context uri to be converted to an absolute uri reference. Such a context is called a base uri and the operation to convert a relative uri reference to an absolute one is called resolving.
  Example: news#top
• resolving uris: Every uri reference can, together with a base uri, be resolved to an absolute uri reference. When the reference is absolute, the resolving is the identity operation. When the reference is relative, RFC 2396 explains in detail how the operation is to be performed. Most often, the path component is relative and resolving it is similar to converting a relative file name to an absolute one.
  Example: ../news#top with base: http://sapportals.com/products/ resolves to http://sapportals.com/news#top
• uri encoding: is a misleading term. What most people mean is that certain characters are represented by their octet number(s) inside an uri. For example the space character is represented by '%20' inside uris. But not only special characters such as '?' and '#' need escaping, but also all characters which are not representable in US-ASCII.
  Coming back to the misleading part: "uri encoding" gives rise to the assumption that there are also unencoded (decoded) uris. This is wrong. When you convert a '%20' back to space, you do not have an uri any longer. This stems from the fact that decoding the encoded characters is not always reversible. Example: 'news%23top' is a valid uri reference without a fragment identifier. When you decode the octets, you get the string 'news#top' which also is an uri reference, but for a completely different resource! Even worse, when you have 'news%23top#1' it decodes to the string 'news#top#1'. Now, which uri reference was it: 'news#top%231', 'news%23top#1' or 'news%23top%231'?

  Some words on encoded chars in URIs: the historical understanding was that the character encoding to use is ISO-8859-1. So a German umlaut 'Ä' would be encoded as '%c4'. But this is not enough to put the Euro sign '€' or chinese character sets into URIs. The general consensus nowadays to use UTF-8 character encoding, which means that 'Ä' is encoded as '%c3%84'. The URICodec in this package is prepared to handle UTF-8 encoding and fallback to ISO-8859-1 when the octets are no valid UTF-8.

WCM URIs (Resource IDs)

WCM URIs, a better name would be Resource ID (RID), are used to identify WCM resources on a single server. In contrast to internet uris they

• do not have a scheme,
• do not have a network path component (host name),
• have Unicode as character set and no encoded octets in the path.

What they have in common with internet uris:

• they are hierarchical,
• they identify resources,
• can have a query part separated from the path by a question mark.

Examples: '/documents/report.doc' or '/tmp/Währung-in-€.txt'.

Query Part in WCM URIs

The string representation of a query part in WCM URIs is the same as in RFC 2396 URIs. The reason for this is that a string representation always needs escaped characters (to represent '=' in values for example), so the RFC 2397 method of encoding a query is applied to WCM URIs as well. The WCM URI class has access methods to get/set a query and handle the correct en-/decoding of query parameters internally. See URI for details.

Mapping of WCM to/from Internet Uris

This package provides mapping functionality to convert WCM uris to Internet uris and vice versa.
When a HTTP server/servlet wants to expose WCM URIs (resource ids) as HTTP uris, it just needs to know where in the HTTP uri hierarchy the WCM resources should be made available.
Example: A servlet resides at 'http://sapportals.com/apps/service' and wants to map request uris to WCM resources. The request for '/apps/service/info/index.txt' should be mapped to the WCM resource '/info/index.html'.
The servlet would do the following when servicing a request:

      HttpUrl m_servletUrl = new HttpUrl(
          m_request.getScheme(), m_request.getServerName(), m_request.getServerPort(), 
          m_request.getContextPath() + m_request.getServletPath(), null);

      IUriReference ref = new UriReference(m_request.getRequestURI(), 
                                           m_request.getQueryString(), null);
      URI uri = m_servletUrl.mapToWcmPath(ref);
      if (uri == null {
        // request uri outside servlet uri? Should not happen
      }
  

First, the http url of the servlet itself is determined. Note that your servlet can be accessible unter many different host names and ports, with or without https. So it is wise to calculate the servlet url on every request. Next the request uri and possible query string are placed in a IUriReference object. As the last step, the uri reference is resolved, using the servlet's uri as base, to the WCM URI (resource id).

The reverse mapping would also use the servlet url. Given a WCM URI, the servlet would either generate a http url or a absolute uri reference to hand out to the client (for example as href in a HTML document):

      URI wcmpath = resource.getURI();
      IUri url = m_servletUrl.mapToAbsoluteUri(wcmpath);
      // or
      IUriReference ref = m_servletUrl.toAbsolutePath(wcmpath);
  

This code would convert the resource id '/info/index.html', given the servlet url 'http://sapportals.com/apps/service' to:

• http://sapportals.com/apps/service/info/index.html (IUri)
• /apps/service/info/index.html (IUriReference)

See IHierarchicalUri for further information.

Related Documentation

• RFC 2396 - Uniform Resource Identifiers (URI): Generic Syntax