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Developing
Learn about different Teracloud Streams tools and features to write, compile, run, and test streams applications.
Developing custom operators
Create custom operators if shipped toolkits do not provide the necessary logic or behavior needed for your stream applications.
Best practices
Use these tips to write operators that perform effectively in their application, and in other applications.
Stream punctuation
Punctuation marks are an in-band signals that are inserted between tuples in a stream. They indicate breaks in the data, which can be used by the operator logic.
Window punctuation
Window punctuation is signals that are inserted into a stream that are related to the semantics of the operator. Window punctuation, called Sys.WindowMarker in SPL and Punctuation::WindowMarker when implemented in C++ primitive operators, divide the stream in window boundaries that are defined by the user.

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
Learn about different Teracloud Streams tools and features to write, compile, run, and test streams applications.
- Development concepts
  Development of stream applications consists of several components such as operators, streams, tuples, Streams Processing Language, toolkits, and more.
- Developing stream applications
  Try out tutorials and explore details about stream application development, SPL features, and best practices.
- Developing native functions
  Extend SPL's computational capabilities by creating native functions written in C++ or Java.
- Developing custom operators
  Create custom operators if shipped toolkits do not provide the necessary logic or behavior needed for your stream applications.
  - Types of operators
    When developing new operators, developers need to choose the kind of operator to implement based on the task they want to accomplish, the programming language they want to use and the trade-offs they are willing to make between generality and ease of implementation.
  - Primitive operator artifacts
    Each primitive operator is stored in a directory whose name follows the format ([:alnum:]+\.)*[:alnum:]+ where the last part ([:alnum:]+) is the operator name.
  - Developing primitive operators
    You develop new primitive operators by implementing them in the C++ or Java™ language. You must define an operator model that describes the syntax and semantics of the operator and implement the operator logic by creating the header and implementation code generator templates.
  - Creating C++ libraries for operators and native functions
    To enable operators and native functions, you must compile with the appropriate include file paths and options and link any shared libraries against the correct runtime libraries.
  - Best practices
    Use these tips to write operators that perform effectively in their application, and in other applications.
    - Window support
      When you write a primitive operator, you might need to maintain a set of recently processed input tuples to compute the operator output. It might be sufficient to use Streams Processing Language (SPL) support for windows.
    - Operator naming conventions
      Operators perform a specific, limited function and are available for programmer use in the toolkits. Along with streams, operators are the most fundamental concept in the Streams Processing Language (SPL).
    - Custom output functions
      Custom output functions are operator-specific routines that can be called from the output clause of an operator.
    - Stream punctuation
      Punctuation marks are an in-band signals that are inserted between tuples in a stream. They indicate breaks in the data, which can be used by the operator logic.
      - Window punctuation
        Window punctuation is signals that are inserted into a stream that are related to the semantics of the operator. Window punctuation, called Sys.WindowMarker in SPL and Punctuation::WindowMarker when implemented in C++ primitive operators, divide the stream in window boundaries that are defined by the user.
        Configuring input ports
        You have the following three choices when you configure the punctuation mode of input ports: Expecting, Oblivious, and WindowBound.
        Configuring output ports
        You have the following three choices when you configure the punctuation mode of output ports: Generating, Free, and Preserving.
      - Final punctuation
        Final punctuation is a special marker that indicates the end of a stream. Final punctuation, called Sys.FinalMarker in Streams Processing Language (SPL) and Punctuation::FinalMarker when implemented in C++ primitive operators, indicates that the stream no longer carries new tuples.
    - Control ports
      Control ports are operator input ports that receive tuples that update the internal operator state. These ports do not generate output tuples through submit() calls. Control ports are useful to dynamically control the behavior of the operator by changing a filtering condition, for example.
    - Default values for operator parameters
      Operators that accept optional parameters at their invocation site must provide default values or require the parameter to be provided. Choose default values that are safe, that do not adversely affect performance, and that follow the principle of least surprise.
  - Performance recommendations
    These tips help you to improve performance of your primitive operators in C++.
- Developing custom toolkits
  Bundle and reuse custom functions and operators across several stream applications by creating custom toolkits.
- Working with files
  Applications and operators can read and write to files in several ways. If relative paths are used, the data directory is used as the root of relative paths. To enable logic to access the runtime application or toolkit directory hierarchies, language-specific functions can be used.
- Enabling Streams data exchange
  Teracloud® Streams provides a data exchange REST API for inserting and retrieving tuples within a job to easily integrate with other data services and external applications. Stream applications can enable the data exchange feature by using one or more Endpoint operators.
- Debugging stream applications
  Debug stream applications using the interactive, command line-based Streams Debugger (sdb).
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.

Window punctuation

Window punctuation is signals that are inserted into a stream that are related to the semantics of the operator. Window punctuation, called Sys.WindowMarker in SPL and Punctuation::WindowMarker when implemented in C++ primitive operators, divide the stream in window boundaries that are defined by the user.

When you develop a primitive operator, specify the window punctuation configurations for both input and output ports. Input ports can be punctuation Expecting, punctuation Oblivious, or WindowBound. Output ports can be punctuation Generating, punctuation Free, or punctuation Preserving.

The Teracloud® Streams instance does not automatically forward window punctuation. You must add logic into the operator code to forward when that is the declared behavior in the operator model (such as a punctuation preserving output port).