TreeView Servlet Control |
TreeView Control and search crawlers |
Why servletsTree like navigation elements are widely used in web sites designs. Most popular are JavaScript based implementations, since they have very sleek appearance and do not require server access for their traversing. Some limited drag and drop operations are possible too. However, due JS performance and memory limitation, they can't handle too big trees (usually 1000 nodes is limit). Even more sleeker can be a Java applet or ActiveX control implementation, however they require certain type of VM or browser. So, if your requirements to have dynamic or very big tree or supporting any browser and platform, then server side tree controls can be only solution. Server side implementation can be based on any server side scripting, like PHP, ASP, or JSP. However this particular example is servlet based, just to demonstrate power ness of servlet technology. Implementation notes
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Where is a problemGenerally number of states can reach O(n!) at traversing of a tree, where n is number of nodes. Obviously it makes impossible for web crawlers to traverse entire tree. So, such popular crawlers as google, simple stop at certain point and significant part of web site can be left not indexed. For example this page you will never see in any search engines. I know only one crawler designed by IBM research center which capable to index most of pages navigated over a tree control. Therefore if you need to get your page indexed reachable through a tree control, then provide all links in hidden <div> on first page for all such page. Since search engines will provide a wrong referer for such pages, should have JavaScript, which checks if a page displayed as standalone and automatically reload page in framed form controllable by a tree control. |