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

One of the problems in the Real Estate Industry revolves around the numbers assigned to listings by Multiple Listing Services. Six, seven, eight, or more numerical digits may be assigned to an individual MLS listing number along with possible alphanumeric characters preceding the number.

From my research, listed below are ten randomly selected, real world MLS numbers I extracted from a daily Google Alert listening for text string ‘MLS#’:

• MLS# 829710
• MLS# 90035087
• MLS# 4240855
• MLS# H740907
• MLS# 9088503
• MLS# 100006059
• MLS# M1366719
• MLS# MC5555362
• MLS# H741473
• MLS# 4334588

Lacking Visual Meaning

The problem with these numbers and others is that they have no visual value or meaning to a user. MLS numbers are stored and generated within datatbases by MLS providers. Since these numbers are required to be unique, a field type of serial is assigned to the field which increments the next unique MLS number by 1 to enforce a primary key’s uniqueness. However, this system does not benefit the user from deciphering where the listing is located nor any other details.

Duplication Misery

Another problem is that there are hundreds of MLS’s in existence and the probability of the same number assigned to two different listings in two different MLS databases is highly probably. If a user only has the number to reference, which listing number is which? And how much time is lost trying to figure out which listing corresponds to which MLS database?

Zero Reusability

Since MLS numbers are simply incremented by 1, the opportunity for number reuse is eliminated. A provider’s MLS numbers will continue to increase by 1 which will increase the number of digits of the MLS numbers over time. Having no delimiters, MLS numbers become humanly impossible to remember since the average human is said to only have the capacity to remember up to 7 consecutive digits. But looking at the random MLS numbers I collected above , a high percentage of real world MLS Numbers either equal or are greater than 7 digits.

The Solution

The Scheme

The MLSN URL scheme is used to designate Internet MLS listings accessible using MLSN (Multiple Listing Service Network). The scheme adheres to IETF’s RFC1738 which describes syntax for strings representations or URLs via the Internet.

The Registrar Assigned Number

After a user posts a listing to a registrar, a 3-octet number is assigned to a listing just like an IP address is statically assigned to a machine or device. But in the case of the MLSN protocol, 3-octet numbers are dynamically assigned to allow for reusability. After a listing expires, the 3-octet number returns to the registrar’s pool to be later reassigned to alternate user’s listing.

For example:

User registers listing with AlicesMLS and receives the following MLS Number URL Address:

mlsn://1.1.21@32821.840

The listing expires after 30 days and 1.1.21 returns to the registrar’s pool of mls numbers and is reassigned to another user’s listing:

mlsn://1.1.21@32819.840

The new MLS URL Address reuses 1.1.21, but is a different listing from the previous listing.

Note: 1.x.x is designated as a reserved Class A block of numbers and used for testing purposes.

The Postal Code

By adding a local postal code to the URL, the listing becomes visually meaningful. Just by looking at the URL, a user can tell if the MLS listing is located in an ideal or non-ideal postal code area. In addition, postal codes are used by the majority of the world’s countries which makes MLSN URL’s extensible to potentially cover any property in the world.

The Country Code

Keeping the global MLS market in mind, a 3-digit country code follows the postal code. Every country is designated with an ISO 3166-1 3-digit number.

This number enhances an MLS Number URL for reusability and visual meaning when coupled with the postal code.

The Port

Two weeks ago, I secured internet port 32801 with IANA on its list of registered ports.

mlsn            32801/tcp   Multiple Listing Service Network
mlsn            32801/udp   Multiple Listing Service Network
#                           Corey Leong  27 January 2010

The purpose of this new port will be to send and receive request and response messages from client machines to designated mlsn servers. This type of messaging mirrors the whois service which enables a user to lookup domain names over port 53.

The Resource

Using a RESTful approach, a resource appended to the URL string permits lookup of a particular attribute of the listing.

For example:

A client sends the following request to an mlsn server.

mlsn://1.1.17@32802.840/status

The mlsn server returns “active” to the client, then the connection is severed.

Other potential resource lookup scenarios include beds, baths, square footage, price, etc.

Conclusion

The above information is a high-level perspective of the Multiple Listing Service Network (MLSN) Protocol, URL, and Port. MLSN is in development mode. Eventually, MLSN will be used by any user to query MLS Listings from registrars over the Internet.

I intend to continue testing a multitude MLS Number URL strings until this protocol reaches full 1.0 version.

–Corey

This past weekend I submitted our online application for a new user registered port with IANA. Here is a simple client server model depicting requests and responses.

The protocol, Multiple Listing Service Network (MLSN), will involve online users and applications querying a real estate database of listings.

I’ll post more diagrams and information regarding this protocol/port as we draw closer to our application being approved.

–Corey

This is a first pass at building a use case model for real estate project management. As you can see on the left side of the system, there are five actors: the project manager, salesperson, administrative assistant, buyer, and the seller. On the right side of the model are three external systems which interface with the model. They are Google Wave, SalesForce, and OpenProj.

The system’s use cases are self-explanatory and may need refactoring. Again, this is a first pass. In addition, I’m sure more use cases will rear their heads so I expect the number of use cases to grow.

Feel free to leave comments and suggestions for this model is open for public comment.

–Corey

The user of the system interfaces with a browser on a desktop computer or an application on a mobile device. The middle tier is comprised of JBoss Application Server and Apache’s ServiceMix. I chose JBoss AS to allow for enterprise javabeans to be used along with all of the lovely enterprise features such as remoting, security, transaction management, presistence, messaging, resource pooling, concurrency control, and directory services.

I included a servicemix implementation component to jboss for deploying a webservice to external webservice clients. In addtion, servicemix allows for xmpp implementations along with messaging services over Java Messaging Service (JMS).

For authorization, an OpenID provider is accessed for warehousing usernames and passwords. Having users’ credentials stored by an OpenID provider removes the potential possibility of a security breach regarding usernames and passwords.

Lastly, I selected PostgreSQL for the application’s database layer. I have used PostgreSQL with many projects previously while the zero licensing cost to implement is most ideal.

To continue this development drill, I will next blog activity diagrams from using the potential use cases.

–Corey

As always, I am open to ideas so please feel free to post comments.

The day will be announced in the coming days.

–Corey

I resolve to:

1. finish and publish my first book online, pdf, and ebook version.
2. finish and submit the OpenMLS protocol specification to IANA.
3. release Remetal 1.0 specification.
4. release RealDF 1.0 specification
5. release version 1.0 of the OpenMLS Registrar Handbook.
6. develop and release beta version of OpenReal, a public real estate data portal.

I look forward to accomplishing these goals for 2010.

– Corey

As you can see, I’ve defined just three types of Actors: Professionals, References, and Guests. I’ve also defined two external entities, OpenID and a web service. The scenarios listed are a first pass and expect to refactor their associations while adding/removing some. I won’t go into detail here regarding the scenarios, but if you would like to follow the wave and/or offer comments, please feel free to contact me on google wave. My gwave account is corey.leong@googlewave.com.

My next step in this process is to create component, deployment, and behavioural diagrams. I’ll post these also to my blog in the future.

–Corey

For the past two seasons, I’ve been experimenting with the idea of showing and reviewing game video to my players at practices for instructional purposes. My players are between the ages of 9 to 12 and are heavily into video gaming such as Modern Warfare 2 and NBA 2k10. So integrating
video with a gaming device seemed like a perfect match for displaying our film footage from games.

In creating a solution I decided to use a handheld PSP, a component av cable, and an HD 19″ monitor. The specific hardware follows:

• PSP 2000 Console
• PSP Component AV Cable
• 19″ Sharp 720p LCD HDTV
• Sony 8 GB Memory Stick PRO Duo

Once I have the previous game encoded into an mp4 format I then connect the psp to one my macs via usb cable. I then copy the mp4 file to the memory stick on the PSP. The average size for an mp4 game file is about 200mb.

After disconnecting the PSP from the mac, I then connect the PSP to the HDTV with the component AV cable. On the HDTV, I select the correct input. And finally, on the PSP navigate to Settings > Connected Display Settings > Switch Video Out > Select ‘Yes’ when asked if you want to display output on a connected device? > Video > the mp4 game file.

To playback, fastforward, or rewind just use the navigational keys and video options on the PSP.

For a future direction, I look forward to Apple’s tablet being released in 2010. A tablet would eliminate the need for a stationary monitor and separate handheld device and merge the two together.

–Corey