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Developing
Develop stream applications with the Streams Processing Language (SPL), Java, and Python.
Debugging stream applications
The Streams Processing Language (SPL) Streams Debugger (sdb) provides a command line-based interactive debugger for debugging stream applications.
Debugging with the Streams Debugger
When the application is started either in stand-alone mode or distributed mode, the Streams Debugger displays initial messages and presents a command line.
Suspending execution with breakpoints
You set a breakpoint with the Streams Debugger to suspend execution of your application.

Welcome
Learn about the core capabilities of Teracloud® Streams, its architecture, and key concepts.
Installing
Use this information to install, upgrade, and uninstall the Teracloud® Streams product.
Configuring
Create a basic or an enterprise domain which is a single point for configuring and managing common resources, security, and instances.
Administering
Administer the product by using the Teracloud® Streams graphical user interface, APIs, or the streamtool command-line interface.
Developing
Develop stream applications with the Streams Processing Language (SPL), Java, and Python.
- Development concepts
  Development of stream applications consists of several components such as operators, streams, tuples, Streams Processing Language, toolkits, and more.
- Writing stream applications
  Teracloud® Streams provides features and functions to help you write your applications to fulfill your business needs.
- Enabling Streams data exchange
  Teracloud® Streams provides a data exchange REST API for inserting and retrieving Streams job data. You can add one or more endpoint operators to your Streams application to enable Streams data exchange. Providing a standard REST interface for Streams data exchange eases the integration of Streams data with other data services and externally hosted applications.
- Compiling stream applications
  The Streams Processing Language (SPL) Compiler is called sc and is included with the Teracloud® Streams installation package. You compile SPL to create files to run on your Teracloud Streams instance.
- Performance improvements for stream applications
  You can improve the processing of your stream application by following these guidelines and tips.
- Debugging stream applications
  The Streams Processing Language (SPL) Streams Debugger (sdb) provides a command line-based interactive debugger for debugging stream applications.
  - Samples used for illustration
    The WordCount sample is used to illustrate the debugger features.
  - Compiling an application for debugging
    To compile a stream application for debugging with the Streams Debugger (sdb), you must specify the -g option on the sc command.
  - Debugging an application in stand-alone mode
    The SPL compiler generates a stand-alone executable program that can be run without a Teracloud® Streams instance.
  - Debugging an application in distributed mode
    A stream application is debugged in a job that is submitted to a running Teracloud® Streams instance.
  - Debugging with the Streams Debugger
    When the application is started either in stand-alone mode or distributed mode, the Streams Debugger displays initial messages and presents a command line.
    - Stream debugging based on operator ports
      The Streams Debugger provides a port-centric view into the stream application.
    - Probe points and probe point IDs
      Probe points include breakpoints, trace points, and inject points.
    - Suspending execution with breakpoints
      You set a breakpoint with the Streams Debugger to suspend execution of your application.
    - Continuing execution of a stopped breakpoint
      When you are stopped at a breakpoint, you continue execution with the (c)ontinue command.
    - Changing attribute values in tuples
      With the Streams Debugger you change values during a debugging session.
    - Dropping tuples from flow
      You can drop a tuple or punctuation from a port while debugging.
    - Tracing tuples with trace points
      You can trace the flow of tuples and punctuation through the ports of an operator.
    - Inserting tuples with inject points
      You can insert new tuples and punctuation into a port with an inject point.
    - Conditional probe points
      To make probe (break or trace) points conditional, you add an expression predicate to the probe point.
    - Debugging source code using gdb
      When a breakpoint is stopped for an input port, you can use the gdb command to have the Streams Debugger provide some commands for inspecting the application elements that can be observed while debugging. Start the gdb source code debugger for the operator process method.
    - Displaying operators, ports, and schema information
      The Streams Debugger provides some commands for inspecting the application elements that can be observed while debugging.
    - Searching for attributes
      The find command helps to locate attributes among all of the ports available in the debugger environment. You can search by attribute name, attribute type, or both with regular expression matching.
    - Saving probe point tuples to a file
      The save command can be used to save the tuple data for a breakpoint or trace point to a file for later use.
    - Saving and loading debug configuration
      The savecfg and loadcfg commands can be used to save your debug session and reload it during a subsequent debug session.
    - Setting console logging and tracing options
      You change the level and format for logging and tracing with the setdbg command.
    - Restrictions debugging an SPL program
      There are restrictions when you debug an SPL program with the Streams Debugger.
    - Streams debugger commands
      The Streams Debugger provides a set of commands to help you debug your application.
- Developing toolkits and operators
  You can create custom toolkits and operators for your applications.
Troubleshooting
Resolve problems with Teracloud® Streams using the troubleshooting tools provided with the product as well as the resources offered by Teracloud Support.
Reference
Find details on the SPL language, toolkits, APIs, commands, and more.
Glossary
Use this glossary to find terms and definitions for Teracloud® Streams.

Suspending execution with breakpoints

You set a breakpoint with the Streams Debugger to suspend execution of your application.

A breakpoint is set with the following command:

b <operator-name> (i|o) (<port-index> | *) [d] [p <predicate>]

For example:

(sdb) b CountAllLines o 0
    Set + 0 Breakpoint CountAllLines o 0 stopped:false

This command establishes a breakpoint on the output port (o) identified with port index zero (0) for operator CountAllLines. The output from the command indicates that the breakpoint is set. The plus sign indicates that the breakpoint is enabled, the number zero (0) following the plus sign is the breakpoint identifier. The output also indicates that application is not currently stopped at the breakpoint.

You can use the optional d parameter to define a breakpoint that is initially disabled. While a breakpoint is disabled, it does not suspend execution when tuples arrive at its associated port.

You can use the optional p parameter to provide an SPL expression that is used as a predicate to conditionally suspend execution of the breakpoint.

When a breakpoint suspends thread execution due to the arrival of a tuple or punctuation at a port, the breakpoint and tuple or punctuation information is written to the console as shown here.

(sdb) + 0 Breakpoint CountAllLines o 0 dropped:false stopped:true lines, 47, int32 wcs, {words=229,chars=2111}, tuple<int32 words,int32 chars> (sdb)

The first line of output identifies the currently stopped breakpoint and includes the following parts.

Plus sign that indicates the breakpoint is enabled
Operator name, port type (i for input, o for output), port index
Current conditions such as stopped:true to indicate that the breakpoint is stopped and dropped:false to indicate that the current tuple is not dropped from the flow.

The remaining lines show the contents of the tuple for the currently stopped breakpoint. There is one line for each top-level tuple attribute value that shows:

Field name, as in wcs.
Field value, as in {words=229,chars=2111}.
Field type, as in tuple<int32 words,int32 chars>.