Data Distribution Facility Documentation

Programming Guide

Release Notes

Frequently Asked Questions

  1. Where do I get authentication credentials?
    An email containing user name and password is sent to the email address submitted as Technical Contact when data feeds are registered in http://tools.realtorlink.ca.  The owner of the data feed can view credentials when editing the feed on the Data Feeds page.
  2. Why do I keep getting prompted for credentials when doing an HTTP GET transaction?
    When doing an HTTP GET request to the server, the Query value needs to be URL-encoded. Failure to properly encode can potentially cause rejection of the entire request, or incorrect responses from the server. For example, instead of sending Query=(ID=0+), use Query=(ID=0%2B). Instead of sending Query=(ID=1234,5678), use Query=(ID=1234%2C5678).A complete URL encoding reference can be found here:
    http://www.w3schools.com/tags/ref_urlencode.asp
  3. Why is the RETS client/library I’m using unable to get search results?
    Common RETS clients, such as libRETS, may not support Standard-XML format for search results, which is the only format available from CREA’s DDF® Data Feed.
  4. How do I build a DMQL2 query to search, such as on a price range or property type?
    CREA’s DDF® Data Feed supports only a limited set of queries.  If you want to filter search results, this must be configured when registering/editing the data feed in http://tools.realtorlink.ca.
  5. What is the difference between ID and ListingID in the Property Details payload?
    IDis the unique identifier for the property within CREA’s system.  This is the key that should be used when querying DDF® for a specific property.  ListingID is the well-known identifer (e.g. MLS #) for the property that is typically generated in originating local board/association system.  Since the property data being retrieved can potentially come from multiple originating systems, there is potential for the same ListingID to belong to multiple properties, so ListingID value should be used only for display purposes, and not as an identifier in DDF® client systems.
  6. What are the requirements for running the sample code?
    The sample code download contains a complete Visual Studio 2010 solution coded in either C# or VB.NET.  If you are using an earlier version of Visual Studio, you should be able to copy the code from DataFeedExample.cs or DataFeedExample.vb into a blank Visual Studio solution and compile successfully.  The app.config contained in the solution should also work without changes in older versions of Visual Studio.
  7. Why do I receive a response telling me “‘HTTP Method not allowed”?
    CREA’s DDF® Data Feed runs as a Windows Communication Foundation (WCF) service, with a set of URI templates describing the parameters supported (e.g. Resource, Culture, Format).  If a request is received that matches none of the defined templates, the service has no way of understanding what the request is asking, so replies with “HTTP Method not allowed”.  If you receive a response like this, review the URI in your request and make sure you the URI is correct, and that all required arguments are included.
  8. I’m able to Login successfully, but every subsequent search fails with a ‘Not Logged In’ response.  What am I doing wrong?
    A “Not Logged In” error being returned after a successful Login is likely occurring because you are not including the X-SESSIONID cookie that was set in your Login response.  This X-SessionID value needs to be submitted with every request after logging in.  CREA’s DDF®Data Feed validates that the X-SessionID and credentials match on every request, so if its missing, you’ll get a “Not Logged In” response.The RETS 1.7.2 specification requires clients to include any cookies set by the server:
    http://www.reso.org/specifications (See section 3.3 Required Client Request Header Fields)
  9. Why do I receive a reply code 20514 “Requested DTD version unavailable”?
    This reply code occurs when an invalid Format argument is included in the request.  Standard-XML is the only supported format.  The server should default to this if the argument is not included (as our documentation suggests).  Unfortunately, it currently treats it as a required argument.  This will be corrected in an upcoming release, so that Format is no longer mandatory.
  10. Why are requests for METADATA-TABLE are only returning a single value? This reply code occurs when an invalid Format argument is included in the request.  Standard-XML is the only supported format.  The server should default to this if the argument is not included (as our documentation suggests).  Unfortunately, it currently treats it as a required argument.  This will be corrected in an upcoming release, so that Format is no longer mandatory.In general, RETS Metadata lookup tables provide a list of fields that can be used for 2 purposes:

1)      building queries (e.g. return all properties in the $300K-$500K range, with 3+ bedrooms)

2)      indicating which fields the user would like returned (e.g. return only Address, Price and BedroomCount for each listing)

By design, CREA’s DDF® service does not allow ad-hoc querying.  Clients are expected to pull all listings available to them, and not choose a subset at runtime.  If the registered owner of the destination wants filters applied to their data feed, they can be configured in the DDF® dashboard (http://tools.realtorlink.ca).  The only value that can be directly queried is the ID field for each resource type.

CREA’s DDF® service also does not allow clients to customize the data included in the response.  All DDF® clients receive the same Standard-XML data payload.  The RETS Select concept that users can pick and choose which value to include is more practical when providing Compact (i.e. tabular) data, which is not supported.  Since clients cannot customize the format of the results, data fields are not required in metadata calls.

 

Sample Code

Client Sample Code (use Visual Studio 2010)

For more information contact CREA Member Support.

Phone: 1-888-237-7945

Email: support@crea.ca

The Canadian Real Estate Association
Phone: 613.237-7111 Email: info@crea.ca

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