TQL programming rules and best practices

Namespaces are logical domains within the Striim environment that contain applications, flows, their components such as sources, streams, and so on, and dashboards.

Every user account has a personal namespace with the same name. For example, the admin user has the admin namespace.

Every Striim application exists in a namespace. For example, if you install an evaluation version using the installer, the PosApp application is in the Samples namespace.

See Using namespaces for more information.

A Striim application consists of a set of components and the connections between them. Some components may be connected directly, others must use an intermediate stream, as follows:

Inner joins may be performed implicitly by specifying multiple sources in the FROM clause. For example:

FROM PosData5Minutes p, HourlyAveLookup l

Other joins must be explicitly declared. See CREATE CQ (query).

A join must include bound data, in other words, at least one cache, event table, WActionStore, or window. For example, assuming that

StoreOrders is a stream that originated from a source and ZipCodeLookup is a cache, the following is valid:

SELECT s.storeId, z.latVal, z.longVal
FROM StoreOrders s, ZipCodeLookup z
WHERE s.zip = z.zip

When joining events from multiple streams, the CQ's SELECT FROM should reference windows rather than streams. See the LargeRTCheck and ZeroContentCheck flows in the MultiLogApp sample application for examples. Define the windows so that they are large enough to include the events to be joined. If necessary, use the GRACE PERIOD option (see CREATE STREAM) and/or a sorter (see CREATE SORTER) to ensure that the events' timestamps are in sync.

You must create a component before you can reference it in the CREATE statement for another component.

*When an application contains only one flow, it does not need to be explicitly declared by a CREATE FLOW statement. See PosApp for an example of an application with a single flow and MultiLogApp for an example with multiple flows.

**When a stream is created automatically by referencing it in a source's OUTPUT TO clause, it will use the built-in type associated with the source's adapter, so it is not necessary to manually create the type first.

Names of applications, flows, sources, and so on:

Components cannot be renamed. In the Flow Designer, you can copy a component and give it a new name.

TQL supports SQL-style comments. For example:

-- The PosApp sample application demonstrates how a credit card
-- payment processor might use Striim to generate reports on current
-- transaction activity by merchant and send alerts when transaction
-- counts for a merchant are higher or lower than average for the time
-- of day.

CREATE APPLICATION PosApp; ...

To make your TQL easier to read, we recommend grouping statements by CQ or flow and preceding each group with explanatory comments as necessary. See the TQL source code for the Sample applications for programmers for examples.

You can include one TQL file in another by reference. For example, if part of PosApp were in another file, you could include it in the main file using:

@Samples/PosApp/PosApp_part_2.tql;

You must specify the path relative to the Striim program directory or from root. If you do not, the include will fail with a "file not found" error.