Plug-ins are responsible for retrieving, processing and storing data. Each time you run backup, restoration or synchronization, data stream is passed through a series of plug-ins.
There are three types of plug-ins:
For convenience of terminology, term “plug-in” in this manual is used to refer to Data Source and Storage plug-ins, and all processing options are referred to as “filters”.
Simply speaking, plug-ins contain instructions on what needs to be done to copy the data. Instructions are plug-in-specific and depend on direction of copying. For example, copying from a database plug-in (backing up) will use SELECT statements, and copying into a database (restoring) will use CREATE and INSERT statements.
Each plug-in creates a virtual file system and allows working with its data as with “common” files and folders. All plug-ins support the same set of operations, which allows the program’s core to work with abstract data stream without knowing any details about it. To learn more, please see Plug-in File Systems.
Plug-ins and Filters in the Architecture
Plug-ins are a part of Workstation, and therefore are platform-specific. For example, 32-bit version of Workstation will not be able to access data of 64-bit version of Microsoft Exchange Server.
Say that you want to back up a local file to an FTP server, with ZIP compression. To perform this operation, Workstation must have the Computer and FTP plug-ins, and the ZIP filter. Also, Server must have a valid FTP Configuration for the FTP plug-in. Architecturally, the scheme works as follows:
Technically, Workstation doesn’t “know” anything about the data it copies and about filters it uses to process it. It takes a data stream from Data Source plug-in, passes it through Filters, and then sends it to Storage plug-in.
You can learn more about plug-ins in the next chapters.