The Target Service Agent (TSA) is a target-specific process that interacts with the Target Service's file system to read, write, and scan data. Each TSA reflects the features and limitations offered by the Target Service. If the Target Service has a hierarchical file system, the Target Service offers options that pertain to a hierarchical file system (for example, traversing the file system tree).
Targets services differ in the type of data sets they contain and the methods used to scan (search for) them. For example, one target has a flat file system while another has a hierarchical file system. When scanning for data sets on these targets, the option to exclude files under a directory does not exist under a flat file system.
Each TSA provides different options such as traversing the file system, excluding all databases, or backing up a file server. Since the engine should not know these differences, SMS provides a way for each TSA to express the options and resources available to the user. Each TSA defines a list of strings that describe its options and resources. The engine retrieves these strings, presents them to the user for selection, and notifies the TSA of the user’s selections through bit maps or values.
There are two categories for TSA options:
TSA-specific options are unique to a specific TSA. For example, a NDS TSA might offer the option to restore only the objects of distinguished name, while a filesystem TSA might offer the option to restore all *.exe files.
TSA-specific options contain a subset called the predefined TSA options. Because the engine is aware of predefined options (as is every TSA), it can automatically assign these options to the data sets selected by the user for backup or restore.
For example, if the exclude directories and exclude files options are selected, the engine can display all children and parent data sets. The user can then select the desired data sets to backup or restore. The engine can then appropriately assign exlude directories or exclude files to the chosen data set since it knows the type of each data set.
The TSAs are not required to support the TSA-specific options, but each TSA must acknowledge to the engine if a predefined option is supported. The engine does not know about the TSA-specific options.
Generic TSA options are the options common to most TSAs. All TSAs are not required to support these options, but each TSA must acknowledge to the engine whether each option is supported or not. The engine is aware of these options and is responsible for:
Finding out if the options are supported by the TSA.
Providing the strings that name the options.
Communicating the options selected by the user to the TSA.
The TSA builds the strings for the TSA-specific options while the engine builds the strings for the generic TSA options.