Here we look at the most sustainable way to integrate robust cross-federation search into wiki. What we aim to implement is a bootstrapping philosophy which is not reliant on central funding, but compatible with a Decentralised Funding model for wiki.
Recently there have been a number of changes to the way major search engines have made accessible their api's to developers, and their are currently no good free indexing and crawling solutions for wiki sites.
# Google Custom Search Google Custom Search can no longer be automatically created through an api, but you must manually upload an XML file, or maintain the list of search engines through the Control Panel interface.
More importantly the JSON API is now heavily restricted for free use to 100 call per day. This may be OK for an individual user running a local site on their laptop but not for shared use and public viewing on the web.
For CSE users, the API provides 100 search queries per day for free. If you need more, you may sign up for billing in the API Console. Additional requests cost $5 per 1000 queries, up to 10k queries per day.
For that we need to embed the search engine using a search plugin that contains the following type of code:
<script> (function() { var cx = '001994538507449046028:ylobtshqas4'; var gcse = document.createElement('script'); gcse.type = 'text/javascript'; gcse.async = true; gcse.src = 'https://cse.google.com/cse.js?cx=' + cx; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(gcse, s); })(); </script> <gcse:search></gcse:search>
It should be possible to separate the search form and display the results nicely as a wiki page. However the links would be normal html links and not wiki elements. The popup style overlay should fit over the relevant wiki page area and opens links in a new tab. It should also allow drag and drop of the links onto a suitable Transporter like area for bringing in the page - developers.google.com 
Below are some links:
