StreamBase's formal path notation is designed to avoid naming conflicts when you run multiple EventFlow or LiveView modules in the same fragment in different StreamBase containers. The notation also allows you to avoid conflicts when operators are run in separate parallel regions.
Use StreamBase path notation to address individual StreamBase containers, streams, or
operators when using certain epadmin
commands or when using the legacy sbadmin and sbc commands. For example, the following commands
show information about the default.BestAsks stream in a
running instance of the Best Bids and Asks sample:
epadmin --ad=adminport --path default.BestAsks --detailed
sbc describe default.BestAsks
For both commands, if the container is default, it does
not have to be stated:
epadmin --ad=adminport --path BestAsks --detailed
sbc describe BestAsks
Path notation is used when configuring StreamBase container connections in a StreamBaseEngine configuration file.
In addition, StreamBase path notation can be seen in the output of many epadmin display commands in the Path = line, and in the StreamBase Manager Operators and Queues Views.
StreamBase path notation has the following syntax, with a period separator between each element:
[containerName.][moduleRefName[[.moduleRef2Name].[..]]entityName
- containerName
-
The name of the StreamBase container hosting the application. Container names are either
system,default, or a name you assign when creating a container. The following examples address two operators with the same name in separate containers:container1.ReadOrders default.ReadOrders
When
containerNameis omitted, the StreamBase container nameddefaultis assumed. Every EventFlow fragment has a default container nameddefault, which contains the application's top-level module unless you explicitly create a non-default container. This means you can often omit thecontainerNameportion of the address. For example, the following commands are equivalent when the server is running the Best Bids and Asks sample in the default StreamBase container:epadmin --ad=
adminportenqueue stream --path default.NYSE_Feed epadmin --ad=adminportenqueue stream --path NYSE_Feed sbc -psbportenqueue default.NYSE_Feed sbc -psbportenqueue NYSE_FeedUse the
containerNameportion of the address when you are addressing a non-default container, or when a name conflict would otherwise occur. - moduleRefName
-
The name of a module that is either referenced explicitly in the fragment, or referenced implicitly by StreamBase. Implicit references occur when a component runs in separate or multiple parallel regions; in this case, StreamBase automatically creates a module for each running instance. There can be multiple
moduleRefNamelevels in the address syntax.The following line addresses an operator named
SumOrderswithin a module reference namedMWindowModuleRef1:MWindowModuleRef1.SumOrders
The next example addresses a group of entities associated with an operator that you have configured, using the Concurrency tab of the operator's Properties view, to run in a parallel region. In each entity, the prefix references the module that StreamBase creates for the operator's parallel region.
MyOperator.InputStream1 (input stream) MyOperator.out:MyOperator_1 (output stream) MyOperator.schema:RetrieveLastOrders (schema) MyOperator.MyOperator (operator)
Finally, If you set a component to run in multiple parallel regions, you can address each region separately. The following example addresses two instances for the same operator, each running in its own parallel region.
default.Filter:0.Filter default.Filter:1.Filter
- entityName
-
The name of an individual stream, operator, schema, or queue.
In StreamBase Manager, you might also see a parallel region instance number appended to the
entityNamein the formentityName[:, using zero-based instance numbers. For example:instanceNumber]Update_Bids_and_Asks:0,Update_Bids_and_Asks:1, and so on.
The container name is an alias for the top-level EventFlow module name. Top-level module names are never included in a path.
Other than the top-level container name, all path elements must be specified from the most significant element to the least significant element. It is illegal to omit more significant elements. For example:
// // Fully scoped path to myOperator // default.childModule.grandChildModule.myOperator // // Illegal path specifier for myOperator // grandChildModule.myOperator // // Legal path specifier for myOperator // childModule.grandChildModule.myOperator