Some WebDAV tools or proven approaches can be used to deploy a new WebDAV-based application or to maintain an existing WebDAV system. 15.5.1 Migrating Existing RepositoriesMany custom applications evolve from previous systems. Over time, these systems tend to become out of date or strain at the seams, and eventually the system may need to be redesigned to take advantage of new technology such as WebDAV. There are three major variations in this kind of task. The simplest is a pure migration, where all the data is moved to a WebDAV system, and the old access methods are no longer available. When a pure migration is not feasible because the old access methods must still be available, there are two choices. First, the data can be moved to a WebDAV-based system and the new repository exposed using the old access method. Second, the data can remain in the non-WebDAV repository, and a WebDAV "wrapper" or access layer can be added. Migrating DataIf it's feasible to migrate data to a WebDAV solution, the job ought to be simpler in the long run. The migration can be challenging, but the resulting system is less complex and should be easier to maintain than a dual-access system. Content can be migrated to the WebDAV repository all at once, but it doesn't need to be. A large insurance company used WebDAV for its new underwriters repository. Because the existing repository was so large, in-house developers wrote some migration tools to transfer documents "on demand" (see Figure 15-1). Figure 15-1. Migrating data to a WebDAV repository.When the WebDAV system was asked for a document, if it hadn't already been migrated the requested document was immediately moved to the WebDAV system so the request could be answered. When the system had some spare cycles, unused documentation was also moved to the WebDAV repository. The old access methods continued to work, and the gateway provided old-style access to documents that had already migrated to the WebDAV repository. Wrapping an Existing RepositoryThis can be the hardest and the least reliable method, but sometimes it's the only choice. The reason it's so hard is that existing repositories rarely have compatible functionality to support WebDAV, if the functionality is there at all. It may only be worth doing if there are compelling reasons to support WebDAV authoring applications. If the old access method (e.g., FTP, HTTP, proprietary protocols, or APIs) must still be available but WebDAV locking must also be supported, the data must be in a repository that truly supports locking. Otherwise, locks are hard to make work correctly through a gateway (see Figure 15-2). Figure 15-2. WebDAV shim or gateway.Here are the major challenges:
15.5.2 Synchronizing Sites and CollectionsSome deployment and maintenance scenarios involve duplicating a large number of files one time or repeatedly synchronizing a large number of files:
Often these situations can be handled nicely with simple synchronization software (made relatively easy by WebDAV servers' support for ETags and last-modified datestamps). Some of the tools that do synchronization include sitecopy for Linux and Xythos WebFile Client for Windows. |