Container Overview

Containers enable a number of useful features. You can:

The following is an example of command-line container commands:

sbadmin addContainer c1 newapp.sbapp
sbadmin addContainer c2 myapp-same-schema.sbapp c2.InputStream=c1.OutputStream

This example defines two containers, c1 and c2, and associates each with an application. The last expression specifies that the output of the c1 container is to be consumed by the input stream of the c2 container. Both containers are running in the same StreamBase Server process.

Each container has its own thread of execution within the containing StreamBase Server. Containers behave much like operators or modules marked with the Run this component in a parallel region setting on the Concurrency tab of the Properties view. On a multi-core machine, one container does not block the execution of another container.

The following set of conceptual diagrams illustrates the ideas behind containers. The first diagram illustrates a configuration running multiple unrelated StreamBase applications in a single sbd process:

In the next diagram, we add two reader applications (B and C) to a running sbd process that was already hosting application A:

In the next diagram, we add two writer applications (B and C) to a running sbd process that was already hosting application A. Then we added application D to write its output stream to the output stream of application A.

The name you assign to containers must follow the StreamBase identifier naming rules, as described in Identifier Naming Rules.

StreamBase's formal path notation is designed to avoid naming conflicts when you run multiple applications in the same server, when you use modules, and when operators are run in separate threads.

StreamBase path notation uses the following syntax, with a period separator between each element:

[containerName.][moduleRefName[[.moduleRef2Name].[..]]entityName

The container name is shown as optional because in most contexts the default container is used and need not be specified.

For additional information, see StreamBase Path Notation.

In StreamBase deployment files, the <application> element has two attributes:

You specify container connections with <container-connection> child elements of the <container-connections> element of deployment files.

See StreamBase Deployment File XML Reference for details on container and container connection syntax. See Deployment File Overview to understand deployment files.

In StreamBase releases before 7.0, the <application> element was part of the syntax of server configuration files, and <container-connection> was a child element of <application>. This syntax is still supported for backwards compatibility.

When an sbd process starts up — with or without an initial application loaded — a container named system is always present and running. The system container has the following output streams:

The URI syntax for addressing StreamBase applications allows you to connect to a particular container in a running application. The URI syntax is:

sb://host:port/container-name

For example:

sb://localhost:10000/holder2

If you leave off the container-name portion of the URI, the container named default is assumed. Thus, the following commands are equivalent:

sbc -u sb://localhost:10000/default
sbc -u sb://localhost:10000

When you specify a container name in the URI, you can omit the container name from any subsequent stream or operator names. For example, the following commands are equivalent:

sbc -u sb://localhost/holder2 enqueue InputStream1
sbc -u sb://localhost enqueue holder2.InputStream1

If you start the server without specifying an application name, the sbd process includes a system container, but no default container. In this case, you may see errors when the default container name is assumed in commands. For example, type the following command in a terminal window or a StreamBase Command Prompt:

sbd -p 9999

This starts an instance of the server on port 9999 without an application running. In another window, type the following command:

sbc -p 9999 list

The response is:

container       system
sbc: Container: default does not exist

See sburi for the details of StreamBase URI syntax.

Some commands that accept StreamBase URIs can specify a comma-separated list of URIs to address two or more StreamBase Servers at once. This feature is used primarily to support a cluster of StreamBase Servers that are using high availability features.

See Multiple URI Syntax for HA Scenarios for a discussion of this subject.

If a server process has multiple containers, you can enqueue to or dequeue from multiple containers at the same time. For example, you can dequeue with a command like the following:

sbc dequeue holder1.OutputStream1 holder2.OutputStream1

If you specify a container name in the URI, you can still dequeue or enqueue from different containers. For example:

sbc -u sb://localhost/holder1 dequeue OutputStream1 holder2.OutputStream1

OutputStream1 will be dequeued from the application in container holder1, while holder2.OutputStream1 will be dequeued from the container holder2.

Because tuples are queued between applications, there is overhead introduced when tuples cross modules.

There are several ways to add a container to a running StreamBase Server process:

You can remove containers from a running sbd server process with the sbadmin command (or with the StreamBaseAdminClient class). For example:

When a container is removed:

The sbc list command (and the underlying Client library) allows you to show all the containers in a running server. The following shows example output from sbc list:

stream ....
schema ...
operator ...
container   default
container   holder2
container   system

The above example shows three containers. Two are defined by the user, and the third is provided by StreamBase.

The sbc describe command shows you the container name and any connections specified when that container was added.

You can use the sbadmin command to manage multiple container-bound applications running in a single sbd process. The relevant sbadmin commands are:

sbadmin {shutdown | suspend | resume} container-name

You can use sbadmin modifyContainer to:

See sbadmin for details on the modifyContainer command.

StreamBase Manager and StreamBase Monitor can display statistics from application running in containers. While running sbmonitor, press c to toggle the display of container names in the Operator Name column.

See StreamBase Monitor and TIBCO StreamBase Manager for more information on the StreamBase monitoring utilities.

Using either the sbadmin addContainer or sbadmin modifyContainer commands, you can dynamically start, stop, and pause enqueuing or dequeuing in containers.

Both commands take the following syntax:

--enqueue=STREAMSTATUS
--dequeue=STREAMSTATUS

The values for STREAMSTATUS can be:

When you interrupt queuing for an application running in a container, you also interrupt queuing for any external clients, input adapters, and output adapters that were communicating with that application. The following table explains how various combinations are affected:

The StreamBase Client libraries for Java, C++, .NET, and Python supports containers. You can write your own applications to connect to and interact with StreamBase Servers and the containers therein.

See API Guide for more information.

The following StreamBase features are not supported with containers: