Real Estate IDX / RETS Plug-Ins – Background

I often see posts on the real estate forums I monitor and participate in, as well as Google and other search engine searches hitting this blog, looking for a plug-in for Joomla or WP for handling IDX, the most common data interface in use today by real estate websites to allow users to search the MLS to find and display home listings, or RETS, a relatively newcomer to the real estate website world. Unfortunately, there is no one “magic wand” or “universal”  solution for this need, and here is why:

The Problem – Different IDX Data Formats

Every MLS in the country has different data in the IDX feed they provide to their Realtor subscribers for website display. This situation is, to a large extent, driven by different housing types and needs in various markets, and also by the long road that Realtor Associations and MLS systems have traveled to get from their humble beginnings to where they are now. Each MLS has traveled a different path, and to a large extent, they continue to pursue different courses, even today. As a result, IDX is not a true “standard”, only a guideline, open to different interpretations and technical implementations.

Some Associations and MLS services embraced the computer revolution early. They may have developed their own in-house, and mostly proprietary and highly customized, MLS databases and programming, designed to suit their particular market and the demands of their local brokers and agents. Other Realtor Associations and MLS services have been less embracing, and less technically capable, and as a result, may have had to rely on commercial MLS applications. While a particular commercial MLS application from one vendor may have a common “core” design, even the vendors have recognized and adapted to the demands of their MLS clients, often highly customizing their systems for each implementation. This applies especially to the IDX data feeds, which may be inherited from earlier implementations by that Association or MLS, and due to the large number of Broker / Agent websites already using it, may be politically and practically difficult to change in any major way. Plus, once a particular version of a commercial MLS application is implemented, it may be years before that Association or MLS upgrades it to the vendor’s latest and enhanced offerings, or migrates to a different vendor entirely. So, the vendor’s product grows and changes, while many of its older clients remain on old releases.

Some Attempts at Open Source IDX Integration

This is not to say that creative developers have not tried to come up with at least a compromise solution. However, as with all compromises, these solutions come with a cost.

For example, one of the most popular open source IDX / MLS solutions available today is web based Open Realty, built primarily with the PHP programming language and utilizing MySQL as its database. It can be implemented as a free-standing web application, or it can be integrated into a Joomla or WordPress website, with some limitations. The major limitation is that the Broker/Agent’s IDX feed has to be imported into the database structures defined by the Open Realty software, with each IDX data field mapped and converted to whatever corresponding Open Realty data element may be its closest match. This is an imperfect process, and may mean that some data elements, which may be deemed crucial in that Broker/Agent’s market, may be lost in the migration, and some data elements may have to be translated into values that Open Realty software understands. In addition, defining how the data is to be displayed on the website can be a tedious and technically challenging task. So, most Open Realty implementations will require a high level of technical expertise to accomplish properly, and in the end, the implementation may be so highly customized as to limit future Open Realty upgrades as the product is enhanced.

RETS Integration – Similar Issues

RETS, a fairly recent development in the MLS data feed environment, seems to be somewhat better defined, from a technical implementation standpoint. However, from a database design standpoint, it is still subject to many of the same variations, limitations and concerns as IDX. In addition, while NAR has declared that all MLS systems provide a RETS feed at some point, it seems that some MLS services are severely limiting access to their RETS feeds, so they may not be available to the rank and file Brokers and Agents. Our own Denver MetroList system is one case in point. It has elected to make its RETS feed available only to a small handful of its “development partners”, meaning vendors willing to pay handsomely for it and implement it under very rigidly controlled guidelines. These implementations are primarily limited to “Virtual Office” applications that brokers and agents must subscribe to from the preferred vendors, and cannot implemented as totally integrated databases on their own websites.