Project Name VieleRETS 1.1
Publication Name System Overview
Publication Date April 2006
Maintainer mlesswing@realtors.org
System Overview Table of Contents
6.0 Frequently Asked Questions (FAQ)
This is a compiled list of the most common problems with the package. Please consult these before sending e-mail for support.
  1. The connection to a MarketLinx server produces a "fclose(): 11 is not a valid stream resource" warning.

  2. I am interested in displaying additional fields that are not selectable from the Administration Interface. I gather that I will need to parse these additional fields out of the metadata returned from the RETS server before I can use these fields. How can I do this?

  3. I know that there are more listings in the MLS than I am seeing. My queries either stop part way through or return no results. What is happening?

  4. Not all of the listing pictures appear, or the primary picture is not the correct picture. What is wrong?

  5. How can I go about getting my results back sorted in order of listing price or any other field?

  6. What should I ask my MLS to determine if I can use this package?

  7. I followed the instructions for the installation, but can't see any data. What did I do wrong?

  8. After installation, I can hook up to the demo feed from Variman, but queries return "No Records Found". What did I do wrong?

  9. After installation, I can't look at listing from a MarketLinx server. I am searching for a MLS number that I know is good. What did I do wrong?

  10. During installation against a server (MarketLinx or MRIS), I receive a warning about the server not being "RETS compliant". What's up with that?

  11. During installation against an Interealty server, I receive an error during that last step of Auto-Detection complaining about not being able to gather test data. Did I just damage the server?

  12. When working with a MarketLinx server, I try to search on a field like "subdivision" with a value that has a space like "aspen grove". No results come back but I know that there are listing that should be returning. Is your software broken?

  13. I an using Retriever (not VieleRETS) and tried to enter a query that should have brought back all listings that have ever been entered in the MLS. I got back some listings, and the package generated a message at the bottom of the page saying that I should refine my search. Can't I see everything?

  14. I can't get batching to work. What can I do now?

  15. Why is it that I can log into some servers using GET versus POST and others I cannot. I would like to use GET style requests, but not all RETS servers appear to support GET versus POST. What is going on?

  16. I am trying to connect to an InterRealty server and I get error messages during Auto-Detection. Will I be able to use VieleRETS?

  17. I can't get images from an MRIS server. What is wrong with VieleRETS?


 1.
The connection to a MarketLinx server produces a "fclose(): 11 is not a valid stream resource" warning.
The server you are working with does not support the "keep-alive" capabilities of HTTP 1.1. You should use the Administrative Interface, traverse to Edit Source->Server Connection to set the KEEP_ALIVE_SERVER setting to "false".
 2.
I am interested in displaying additional fields that are not selectable from the Administration Interface. I gather that I will need to parse these additional fields out of the metadata returned from the RETS server before I can use these fields. How can I do this?
The fields are server dependent. The Admin tool sees all data fields avaiable from the source you direct it to. Our demo server has only a few. Typically, production MLS servers have between 170 and 350 fields.
 3.
I know that there are more listings in the MLS than I am seeing. My queries either stop part way through or return no results. What is happening?
Your server may not be producing XML. MarketLinx servers are known to have this problem. The RETS Standard states that all transmissions between clients and servers should be in XML format.

If you are not familiar with XML, it looks alot like HTML only you can create custom tags. A web page with HTML would normally look something like this: <html> <head> <title>Example</title> </head> <body> Hello there. </body> </html> A RETS transmission in XML format looks something like this: <RETS> <COLUMNS> ListingID ListingPrice </COLUMNS> <DATA> 12345 120000 </DATA> <DATA> 56789 125000 </DATA> </RETS> In this example, listing 12345 has a listing price of $120,000.

OK, not for the problem with servers that do not produce XML. Some fields, like REMARKS, could have data that contains illegal XML characters (like > < or &). This is a huge problem for standard componentry used by software developers. The tools they use to read standard XML responses are called parsers.

Parsers expect servers too convert illegal characters to "escaped" characters prior to transmission. Here is an example:

If the REMARKS that the Agent entered were:

A great house for < $130K & close to the train!

The server should send this (if it was really doing RETS that is) as:

A great house for &lt; $130K &amp; close to the train!

To get around this problem, this package can read non-XML responses. Set the STANDARD_SERVER_RESPONSE setting to "false" for this server.
 4.
Not all of the listing pictures appear, or the primary picture is not the correct picture. What is wrong?
Your server may not be RETS Compliant. MarketLinx and old Rappatoni servers are known to have this issue. The RETS standard is to begin image numbers at 1:

1 - primary photo
2 - second photo
3 - third photo
.....

Some servers are NOT compliant with the standard because they begin numbering at zero:

0 - primary photo
1- second photo
2 - third photo
.....

The MEDIA_LIST_ZERO_START setting should be "true" for this server.
 5.
How can I go about getting my results back sorted in order of listing price or any other field?
The RETS Standard has its own query language called DMQL. It is similar in purpose to the SQL langauge used in tools like MS Access to return data from databases. This is where the similarity stops though. The structure of DMQL is very different.

DMQL has no provision for sorting or grouping data. This package shows the data exactly as it comes from the server.
 6.
What should I ask my MLS to determine if I can use this package?
The first question to ask your MLS is "Do you support RETS (Real Estate Transaction Standard)?". If the MLS answers "no" you cannot use this package. Because of RETS growing popularity, you might want to ask "When will you support RETS?". There are a variety of tools that are now available that tacke advantage of RETS and it may ease the "cutting and pasting" efforts that are required to today. If your MLS does not anything about the standard, you can direct them to Official Site for more information.

If RETS is available, you should then ask for three pieces of information:
  1. RETS URL - this will a text string that begins with http://......
  2. Account Name - Typically, it is the same as your MLS account, but it could be different
  3. Account Password - Again, typically the password from your MLS account, but it could be different
After obtaining this information, you can proceed with either the Quick Installation instructions or the more detailed Step-by-Step instruction set.
 7.
I followed the instructions for the installation, but can't see any data. What did I do wrong?
It could any one of a number of things. When you hook up to a server, the "Auto-Detection" logic tries to present you all of the options that are available. The order is:
  1. Connect
  2. Resource
  3. Class
CRT operates a demonstration RETS server to help you get this package up faster. The name of the server is Variman. Some MLS operations run Variman also. In real world use, you would hook up to your MLS.

If you fail on the "connect" to the demo server, you might want to check your connection to the internet or the server settings.

If the "connect" is OK, we need to examine the next two areas. The demo server only has data in for the Resource called "Property" and the Class called "ResidentialProperty".

When presenting all of the options of a server, this package does not know which options are valid. In the case of the demo server. all Resources and Classes are show. By pure luck, the last Resource shown is "Property". Unfortunately, the last Class shown is MUL (Multiple Unit). Only the Residentailproperty (Residential) class has data.

If you connect to the the demo server, use a Resource of "Property" and a Class of "ResidentialProperty".
8.
After installation, I can hook up to the demo feed from Variman, but queries return "No Records Found". What did I do wrong?
The "Auto-Detection" routine that is run when you hook up a new source returns a list of all valid Resources and Classes that the server supports. These combinations are supported by the server, but it doesn't guarantee that there is data there.

The demo server only has data loaded for the resource called Property and the class called "ResidentialProperty".
9.
After installation, I can't look at listing from a MarketLinx server. I am searching for a MLS number that I know is good. What did I do wrong?
A bug in MarketLinx only handles a size of 1024 characters during GET operations.

There are two things you can do to correct this situation:
  1. From the Administration Interface, specify fewer columns to be displayed in the the Summary, Detail and Gallery views. Fewer than 70 columns appears to be the threshold. This is also the approach if you are using a version of the package that predates Version 2.0.6
  2. If you really need all of the columns, turn the define for POST_REQUESTS variable to "true". You can do this from the Administration Interface->Edit Source->Server Connection panel. This will allow all columns to be viewed.
10.
During installation against a server (MarketLinx or MRIS), I receive a warning about the server not being "RETS compliant". What's up with that?
As of April 2005, the RETS Working Group (the standards body behind the RETS standard) adopted Version 1.7 of the specification. The RETS standard states that the current version and one version back should be supported. The two current versions of the specification are 1.5 and 1.7. You should report this situation to the MLS.
11.
During installation against an Interealty server, I receive an error during that last step of Auto-Detection complaining about not being able to gather test data. Did I damage the server?
No damage done. There appears to be a bug in the Interealty RETS server when requesting integer-based fields greater than a specified value. The "sysid" used by the server is declared as "Int" for integer.
12.
When working with a MarketLinx server, I try to search on a field like "subdivision" with a value that has a space like "aspen grove". No results come back but I know that there are listing that should be returning. Is this package broken?
Not really, but you will have to change a configuration paramter. There appears that MarketLinx server do not accept HTTP requests in URL Encoded format. You can control this by setting the ENCODE_REQUESTS setting to "false" from Administration Interface->Edit Source->Server Connection .
13.
I an using Retriever (not VieleRETS) and tried to enter a query that should have brought back all listings that have ever been entered in the MLS. I got back some listings, and the package generated a message at the bottom of the page saying that I should refine my search. Can't I see everything?
Yes, Retriever can see everything that is in the MLS RETS server if the server supports Batch processing. If not, only 99 listings are brought back for a couple of reasons:
  1. Huge queries are a burden on RETS Servers.
  2. Huge queries will probably freeze the browser of the consumer
  3. Huge queries will make the consumer browser apprae unresponsive
This package is a Free Open Source project though and the governer can be removed if you really want any of the above conditions. It is better to refine the search by adding more conditions.

VieleRETS does not have this limitation.
14.
I can't get batching to work. What can I do now?
Some RETS servers do not support the Limit and Offset options specified by the RETS Standard. this package uses these two options are used to create "batches" of results. Without them, all results are gathered with a single batch and simulates the server capability.

Some debate exists over if the current RETS standard requires offset to be supported, without this we have to fall back to a slower client side pagination. The Auto-Detection logic tries to determine if the server supports theses features.

The following servers have been reported to have the problem.
  1. Interealty
  2. MarketLinx
  3. Rappatoni (old 1.0 server)
The Auto-Detection logic could be flawed though. If you think that your server is actually RETS Compliant, you can override the detected values in the Administration Interface.
15.
Why is it that I can log into some servers using GET versus POST and others I cannot. I would like to use GET style requests, but not all RETS servers appear to support GET versus POST. What is going on?
The authentication used by some RETS servers is based on Microsoft libraries that are known to incorrectly formulate Digest Authentication responses.

Digest Authentication is a standard documented by RFC 1617. Part of the response to a request is including a "uri". If you were looking for the foloowing with a browser: http://www.crt.realtors.org then the uri would be: www.crt.realtors.org As another example, if you were looking for the following: http://demo.crt.realtors.org/rets/login then the uri would be: demo.crt.realtors.org/rets/login The next example highlights the problem and has to do with the passing of parameters. Now lets look for the following: http://broken.rets.org/search?Format=COMPACT The correct uri per RFC 1617 is: <xmp>broken.rets.org/search?Format=COMPACT Servers that use Microsoft libraries incorrectly assume the following: broken.rets.org/search Notice that the arguments are missing. If you are using a RETS client built with Micosoft libraries you will experience the opposite effect. You will be able to connect to Microsoft-based servers but not non-Microsoft servers.

Microsoft was notified of the issue (publically) in 2002 at which time a fix was promised. The fix has still not been issued.
16.
I am trying to connect to an InterRealty server and I get error messages during Auto-Detection. Will I be able to use VieleRETS?
The metadata of InterRealty servers specifies the "sysuid" column as being unique and also sets this column to be not "selectable". This is problematic for the Auto-Detectin logic. The package should try to use the MLNumber field to perform sensing logic.
17.
I can't get images from an MRIS server. What is wrong with VieleRETS?
Nothing is wrong with VieleRETS. MRIS dows not support images through RETS.
System Overview Table of Contents