DAS 1.6 Migration

This page contains information to facilitate the migration of DAS clients and servers to version 1.6 of the specification.

Most of the changes between versions 1.53, 1.53E and 1.6 are additional and non-destuctive. As a result, many servers and clients implementing core parts of the specification in different versions will continue to work together without issue. There are exceptions however, as detailed below. If you are at all unsure as to the version you should use, ask on the mailing list.

Creating clients

You should engineer your client to work with DAS 1.6. However, you should be aware that many DAS servers do not and will not update, and therefore may wish to be fault tolerant and consider including a "legacy mode" to deal with, in particular:

• servers which do not implement a sources command, but a dsn command instead
• sources which provide groups in the features command instead of parents/parts

Creating servers

If you are creating a DAS server, it therefore makes sense to use the latest version you can given the capabilities of the client(s) you expect it to be used with. The server will be more future proof, and have more features and fixes. Whether this means using 1.6 depends on the client.

Clients are generally engineered to work with servers of equivalent or previous version (e.g. a 1.6 client will usually support 1.53 or 1.53E servers). Functionality may not be complete however, simply because some things possible in 1.6 are not possible in 1.53 (for example). In addition, most 1.6 servers are still likely to work fine even if the client does not support version 1.6. This is especially true if the client supports 1.53E. The reason for this is that most of the specification changes are minor and non-destructive (e.g. removal of attributes rarely used, addition of new optional attributes). The major difference to be aware of which may prevent a 1.6 server from working in a legacy client is if the DAS source offers hierarchical features (e.g. genes, transcripts, exons). DAS 1.6 handles this in a different (more flexible) way, and so the features may not be drawn correctly. It should be noted that most DAS sources do not have hierarchical features and will therefore not be affected by this change.

For more specific information and advice, it is recommended you ask on the mailing list.

Client Version Support

Below is a table showing the versions of DAS supported by existing client software. If you can add to or update this information, please do so.

Client	Versions supported	1.6 migration target date
Ensembl	1.53, 1.53E	2011
Dalliance	1.53,1.53E,1.6	complete
Dasty3	1.53,1.53E,1.6	complete

Server Version Support

To find the version of the specification supported by a server, you should consult the DAS Registry.