One of the challenges for buyers in real estate is knowing the most current listing information. The MLSN Protocol resolves this issue for public access to listing information, but it is based upon a request/response protocol. A user must manually query an mlsn server to find out the latest increase or decrease price for a listing. Whereas, the publish/subscribe could be used to receive listing information automatically over the Internet.

In the diagram above, users subscribe to topic message queues using the PubSubListing Protocol. When a listing’s price changes, this update is sent to the messaging server which updates the subscribed topic queues, respectively. The pricing update is broadcasted over the PubSubListing Protocol to the users who then view the new price on their laptop, desktop machine, or mobile device. This broadcast pattern continues whenever the listing’s price changes. Users have the ability to continue to receive future broadcasted messages by remaining subscribed or unsubscribing to the topic queues.

In summary, the obvious benefits of the PubSubListing protocol are the automated messages of changes and the ability to subscribe or unsubscribe to topic queues. The next step for the protocol is to apply for a reserved port with IANA.

One of the major benefits of MLSN URL’s is the ability to reuse assigned MLS Numbers. Using an simple scenario, I’ll go in detail of how reusability works with MLSN URL’s.

In the diagram above, Alice is an owner of an accredited OpenMLS registrar. Her service is located at alicesmls.com.

Bob the seller, needs to sell his house in Orlando, Florida. He registers it on Alice’s MLS for 60 days and receives a unique MLSN URL, mlsn://1.1.1@3203.840.

Unfortunately, Bob’s house does not sell within the 60 days and expires. When this happens, the assigned 1.1.1 or triple short number returns to Alice’s block of MLS numbers to be reused again.

A new seller, Cristy, registers her house in Atlanta, Georgia on alicesmls.com and receives her unique MLSN URL, mlsn://1.1.1@30329.840.

As you can see, 1.1.1 was used once with Bob’s listing and then again with Cristy’s. Each MLSN URL represents two completely different listings, which demonstrates reusability.

By the way, the number 840 in the MLSN URL’s represents the iso country code for the United States.

–Corey

A Simple User Session

Scenario: User wants to know the status of a property listing in the downtown Orlando zip code, 32801, located in the United States.

A user starts a session on a client desktop. He enters the following MLS Number URL at the prompt:

user>mlsn 1.1.1@32801.840/status

The mlsn client application sends the MLSN URL via port 32801 over tcp through the internet to an MLSN Messaging Server which accepts the text string via port 32801.

The MLSN Server routes the URL text string to an application server which parses and creates a query for the database which returns a result.

The result is sent from the application server back to the MLSN Messaging Server which sends the result via port 32801 over tcp back through the Internet cloud.

Finally, the client desktop receives the result via port 32801 and displays the results to the user:

user>active

–Corey