Constellation Roamer FAQ

Here are some common problems encountered when setting up Constellation Roamer for the first time. With any luck, the answers here will make setting up Roamer even easier!

Why doesn't the node's "url" attribute work?

This problem is frequently encountered when running the Roamer visualization off the local filesystem. You'll know if you're doing the same if you see the "file:///" protocol in your browser's address bar.

Flash Player's security model prevents local files from accessing external data including links to websites. To fix this, you'll need to upload it to a webserver, even a local one (i.e., "localhost").

Why doesn't Javascript work? I enabled "use_javascript".

If you see "file:///" in your browser's address bar that means you're running Roamer from the local filesystem and Javascript integration won't work. This is a Flash Player security feature which protects your files from prying eyes.

The solution is to upload Roamer to a webserver, even a local webserver (e.g., "localhost").

Roamer doesn't (seem to) support non-integer IDs! How can I use GUIDs or other strings for node or edge IDs?

When you load up Roamer with integer IDs it works fine but as soon as you switch to other string IDs none of the data seems to load!

Usually, this happens because the default selected node ID is an integer, namely, "1". If the data doesn't contain a node with that ID, nothing is shown.

To fix this, you'll need to set the "selected_node_id" FlashVar in the HTML page. Find out more about placing Roamer in a webpage.

The REST tree mode is making nodes and edges appear and disappear randomly. Help?

This problem is a bit tricky. Roamer requires that you define unique edge IDs in the graph data so it can keep track of them. Many developers increment an integer in the REST tree script to generate IDs. However, these IDs aren't unique across all calls. The result is some edges get overwritten because they had the same ID.

A better way to generate edgeIDs is to concatenate the tail node ID and the head node ID. Here's an example:

var edgeID = tailNodeID + "|" + headNodeID;