Developing Web Apps with Haskell and Yesod, 2nd Edition

Chapter 25. Case Study: Sphinx-Based Search

Sphinx is a search server, and it powers the search feature on many sites. The actual code necessary to integrate Yesod with Sphinx is relatively short, but it touches on a number of complicated topics and is therefore a great case study on how to play with some of the under-the-surface details of Yesod.

There are essentially three different pieces at play here:

Storing the content we wish to search

This is fairly straightforward Persistent code, and we won’t dwell on it much in this chapter.

Accessing Sphinx search results from inside Yesod

Thanks to the Sphinx package, this is actually very easy.

Providing the document content to Sphinx

This is where the interesting stuff happens. We’ll show how to deal with streaming content from a database to XML, which then gets sent directly over the wire to the client.

The full code for this example can be found on FP Haskell Center.

Sphinx Setup

Unlike in many of our other examples, to start with here we’ll need to actually configure and run our external Sphinx server. I’m not going to go into all the details of Sphinx, partly because it’s not relevant to our point here, but mostly because I’m not an expert on Sphinx.

Sphinx provides three main command-line utilities: searchd is the actual search daemon that receives requests from the client (in this case, our web app) and returns the search results; indexer parses the set of documents and creates the search index; and search is a debugging ...