Purpose
If you are already running FME Server's Data Download Service you may want to create an RSS feed of layers available for download. Users can subsribe to your RSS feed and get a current view of the data layers your organization has available.
The RSS feed can include one entry per layer and a link to download that layer with default parameters. The example below could be developed further to create entries for different formats or coordinate systems as well
How it works
The attached workspace uses HttpFetcher transformers to extract the capabilities of your FME Server using your FME Server's REST service. An http request to the REST service returns every workspace registered with the Data Download Service and then another request returns all parameters and their possible values. In this example we look for parameters called THEMES which we know contain layer choices for users in the sample workspace austinDownload.fmw. If you have used other parameter names to expose the layer choices to users the workspace can be modified to look for these other names as well.
The workspace then builds Data Download links for each layer and writes these links as entries to the GeoRSS writer.
When the workspace is published to FME Server and registered with the Data Streaming Service we end up with link that will return RSS with an entry for each layer as shown here.
Steps
1. Download the attached workspace and open in FME Workbench.
2. Change the defaults of the following published parametes to reflect your FME Server environment:
- UserName: this must be an FME Server user with access to the REST Service
- Password: password of the above user
- Destination DataSet: select a directory on your machine for testing, this will not be used on FME Server
- FMEServerRoot: the base url to your FME Server host for example: http://www.fmeserver.com
- Title: Give a title for your RSS Feed
- Description: Enter a description of your RSS Feed
- Author: Enter the name you wish to use as the author of the service
3. Run the workspace in FME Desktop to test it. You should have written an XML file to the destination directory you selected. At a minimum there should be some <entry> features with layers for download from the sample workspace austinDownload.fmw if you have that workspace published to your FME Server.
4. You will likely need to edit the
Tester transformer in the workspace to search for the parameter names you have used for your layer choices if you have not used the parameter names THEMES. For example you may have used the parameter name
Layer so you would add
Layer to the tester.
5. Make all of the published parameters private by right-clicking on each of them and selecting
Convert to Private Parameter6. Publish the workspace to your FME Server and register the workspace with the Data Streaming Service
7. Use the FME Server Web User Interface to run the workspace via the Data Streaming Service. If you use the browser Internet Explorer you should see the entries formated as shown in the image above. You should be able to click on the links to download the layers. FME Server will do the data download using the default parameters is whichever workspace the layer is coming from.
8. The link to your RSS feed can copied from the Web UI if you click on the workspace in Data Streaming Service. The
Show Request button has a C
ompact URL which is the link to RSS feed.
Note on Authentication:If your Data Streaming Service is running in a secure enviroment users will need to enter creditials to see the RSS feed. Similarly, if your Data Download Service is secured users will need to enter creditials to download a layer.