The content crawler's click-through implementation must return content in a readable format and set the content type and file name using the appropriate headers.
The following example uses a file, but the crawled resource could be any type of content. If the content is not in a file, the click-through servlet should create a representation with as little extraneous information as possible in a temporary file (for example, for a database, you would retrieve the record and transform it to HTML). See Creating Temporary Files for Indexing. You can also use the IDK's DocFetch mechanism to handle indexing and click-through; see Implementing Content Crawler DocFetch.