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Netica APIs
(Application Programmer Interfaces)

The Netica APIs are a family of powerful Bayesian Network toolkits. They allow you to build your own Bayesian belief networks and influence diagrams, do probabilistic inference, learn nets from data, modify nets, and save and restore nets.

The API Family

Language Comment
Java Full Netica power, in the Java spirit and style.
C Compact and ultra-fast. Useable by any language with a C interface (C++, Delphi, Fortran, LISP, ...).
C# Latest addition to the Netica API family for MS Windows.
Visual Basic/COM New version with full Netica power for MS Windows.
C++ Pre-release version available. Similar to the Java-API.
Matlab Matlab interface to the Java-API.
CLisp Interface for CLisp users.

General Features

Each Netica API has the following features:

  • World-renowned Engine. All Netica products are founded on the same core software engine. This engine has seen fourteen years of service, enhancement, and field testing, and is now a trusted component of many of the world's leading-edge Bayesian Network applications.
  • Interoperability. All of the Netica APIs use the same Bayesian network file formats as Netica Application, so they can share networks and case files amongst each other.
  • Broad Platform Support. Versions of Netica API are available for Microsoft Windows (95/NT4 to XP), Linux, Sun Sparc, Macintosh (OS 6 to OS-X), Silicon Graphics and DOS. Each of these has an identical interface, so you can move your code between these platforms without changing anything to do with the Netica API. Versions of Netica exist for Java, C, and Visual Basic, and many languages (e.g., C++, Delphi, Pascal, Lisp, Fortran, Cobol) can use the C version. Versions are similar in design to allow for easier porting.
  • Encryption. Applications using proprietary Bayes nets can be deployed while keeping the underlying Bayes nets securely hidden.
  • Strict Quality Assurance. Before releasing any new version of the Netica API, every function is put through rigorous Quality Assurance testing to make sure it operates as designed. Hundreds of real networks and thousands of random networks are generated and solved in multiple ways to check the inference results. BoundsChecker and Purify are used to make sure there are no memory leaks or other memory faults. This level of Quality Assurance combined with a careful initial design and eight years of extensive customer usage has resulted in a rock-solid product.
  • Prompt Support. If you ever find a bug in a Netica API and describe it to us in a detailed enough form that we can reproduce it, we will make it our top priority to fix the bug, and send you a corrected version or a work-around, and aim to do so within 2 weeks.
  • Forward Compatibility. Netica APIs are designed to be easily extended in the future without changing what already exists, so you will not have to change your software.
  • Growth and Continued Support. Many new features are currently under development, and will be incorporated into future versions. The API will continue to be extended for years to come.

Software Features

If you are an experienced software developer, you will appreciate the following features:

  • Speed. The Netica API inference engine has been optimized for speed. It uses the fastest exact algorithms; for example, it compiles Bayes nets and influence diagrams into a junction tree of cliques for fast probabilistic reasoning.
  • Documentation. Each API comes with excellent documentation including example programs and detailed descriptions of each function. They come with a colorized PDF manual suitable for printing, as well as a hypertext point-and-click on-line HTML manual that makes searching for function definitions very fast and easy. The C-API version of the PDF manual includes introductory chapters on Bayes nets, decision networks, learning, and more.
  • Surprise-free, Deterministic Behavior. Programs that use the API completely control it. No API function will ever take any action until called. The API will not do any I/O unless requested to, and all functions take a predictable amount of time before returning. Also, a limit may be set on the maximum amount of memory that Netica will use.
  • Name-space Freedom. Care has been taken to make the Netica API library functions good project citizens. The Netica APIs can be used with other libraries and won't interfere with them.
  • Minimal Dependencies. The C-API does not require any other library than the Standard C library. The Java-API does not require any other set of java packages than those that come with a standard Java 2 environment.
  • Meets Developer Expectations. Each API has an orientation that is suited to developers in that particular programming language. Naming conventions are respected. Exception handling is employed, if available. Appropriate I/O streaming packages are employed. If variable prototypes are supported, they are used in a way that is natural.
  • 100% Compatibility with Netica Application. Many developers find it invaluable to use the Netica Application as a graphical user interface (Windows version only) to the same Bayes nets Netica API uses.
  • Thread Safe. Can safely be used in a multithreading environment.
  • Database Connectivity. Allows direct connection to most database software.
  • User Data Support. Every node and network can store by name arbitrary data fields defined by you. These are saved to file when the object in question is being saved.
  • Flexible Argument Validation. The programmer can control how carefully API functions check their arguments when they are called, including a "development mode" to extensively check everything passed to an API function.
  • Error Handling. The APIs have a simple but powerful method for handling usage errors, which can generate very detailed error messages if desired. The API makes use of exception-handling in those languages that support it.

Bayes Net Features

If you are knowledgeable about Bayesian Networks, you will especially appreciate the following features:

  • Learning. Probabilistic relations can be learned from case data, even while the net is being used for probabilistic inference. Learning from data can be combined with entry by hand and representation by equations. It can handle missing data and latent variables or hidden nodes. Learning algorithms include: counting, sequential updating, fractional updating, EM (expectation maximization), gradient descent and TAN.
  • Advanced Decision Nets. Can solve influence diagrams which have multiple utility and decision nodes to find optimal decisions and conditional plans, using a junction tree algorithm for speed. Handles multi-stage decision problems, where later decisions depend on the outcomes of earlier ones, and on observations not initially known. No-forgetting links need not be explicitly specified.
  • Equation Support. Large and complex probability tables do not need to be entered by hand, if they can be expressed by an equation. The equation language follows a Java/C++ syntax and contains an extensive library of built-in functions, including all the standard math functions and common probability distributions, as well as some functions and distributions suited to Bayes nets, such as Noisy-or, Noisy-max, Noisy-sum, etc.
  • Sophisticated Findings Support. Netica API not only supports the traditional state and real-valued findings, but also virtual evidence, likelihood findings, gaussian distribution findings, interval findings, and negative findings (those claiming that some variable is not in some state).
  • Case Support. Can save individual cases (i.e., sets of findings) to file, and manipulate files of cases. Handles incomplete cases. Can associate a multiplicity and identification number with each case. Allows direct connection to most databases, for case management.
  • Simulation Support. Can do sampling (discrete simulation) to generate random cases with a probability distribution matching the Bayes net. Can use a junction tree algorithm for speed, or direct sampling for nets too large to generate CPTs or a junction tree.
  • Sensitivity. Netica can efficiently measure the degree to which findings at any node can influence the beliefs at another node, given the findings currently entered. The measures can be in the form of mutual information (entropy reduction), or the expected reduction of real variance.
  • Dynamic Construction. Can build networks "on the fly" in memory to support working with dynamic Bayes nets (DBNs).
  • Junction Tree Algorithm. Can compile Bayes nets and influence diagrams into a junction tree of cliques for fast probabilistic inference. An elimination order can be set or Netica can determine one automatically, and Netica can report on the resulting junction tree.
  • Link Reversal. It can reverse individual links or "sum out" (absorb) nodes while maintaining the same joint probability distribution, properly accounting for any findings in the removed nodes or other nodes.
  • Disconnected Link Support. Links may be individually named and disconnected from parent or child nodes, thus making possible libraries of network fragments which you may then copy and connect to other networks or node configurations.


Versions of Netica API are available for most popular platforms, including Microsoft Windows 95/98/Me/NT4/2000/XP/Vista, Linux, Sun Sparc, Mac (68000, PPC: OS 6 to 9 & OS-X), Silicon Graphics and DOS.
If your platform is not on this list, please contact us about the possibility of building a custom version for you.


Commercial $785 
Educational / Personal $285 
C-API Manual + shipping    $145*
Java-API Manual + shipping    $85*
CD-ROM (alone / with Manual)   $45 / $35*
Volume or Site license  Contact Norsys

  • All prices are in US dollars, and include technical support and free upgrades for one year (by download). More pricing info.
  • Your license to the Netica API is to the entire family of APIs. So, if you decide to switch programming languages, that is not a problem. When you purchase a license you receive a license-key. The same license-key works across all the APIs.
  • Your license comes with legal rights and obligations.
  • The Netica API is a separate product from the Netica Application. Each requires a separate license.
* The printed manual and physical CD-ROM disk need not be purchased. Each download distribution comes with a complete manual that you can print yourself. You can also access our online user docs: C API Webdocs    Java API javadocs

Buy Netica API now!

Free Version

A free version of each Netica API is available. The free version has the entire set of functionality as the licensed version and it is not time-limited. It is, however, limited in the size of any net you can construct and save. It is a great vehicle for learning about Bayes nets and about Netica's capability.

To use the free version of an API, simply download the regular version of that API, and pass null to the function expecting the license string.


To download an API for a particular platform, click on one of the following:


Embedded and Server Licensing

If Netica API is used within a commercial product, then a per copy license fee applies, and this must be arranged with Norsys depending on the volume of the product, the price of the product, etc., but is generally very affordable.

If Netica API is used in a web server, a special license is required.
Contact Norsys for more info.


The purchase price includes support via the Internet. For additional support, a service contract is available from Norsys.

You can download new and pre-release versions of Netica and enable them with the same license string as you were originally supplied. Your license string will last for at least a year.

If you are a client of ours, and you find a bug in a Netica API and describe it to us in a detailed enough form that we can reproduce it, then we will make it a top priority to fix the bug, and send you a corrected version or work-around, and aim to do so within two weeks.

To email technical support, click here.



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