Chapter 1 Introducing Jaguar CTS

Component support

Components are reusable modules of code that combine related tasks (methods) into a well-defined interface. Jaguar components are installed on a Jaguar server and contain the methods that execute business logic and access data sources. You or your administrator install the component's executable code on the Jaguar server. Components can be distributed throughout a network, including the Internet or an intranet, on different servers. Installed components can be used by any number of independent applications.

Since Jaguar components reside on the server, components do not contain methods to display graphics or user interfaces--that is, Jaguar components are inherently nonvisual.

User-interface developers or other component developers can browse a component's interface in Jaguar Manager; in their code, they use a client stub or proxy to invoke the component's methods. The stub or proxy acts as a local surrogate for the remote component, providing the same method signatures as the component and hiding the details of remote server communication.

Jaguar's server-side component support and client-side stub or proxy support are independent. Any Jaguar client can execute any type of component. A component of any model can execute components of another model using intercomponent calls without the use of additional gateway software. Additionally, since Jaguar uses standard CORBA IIOP as its core network protocol, you can use CORBA client runtimes from other vendors to invoke components installed on a Jaguar server.

All clients and components share a common interface repository. Component interfaces are stored in standard CORBA Interface Definition Language (IDL). Component developers can define, edit, and browse interfaces in Jaguar Manager. Jaguar Manager allows you to edit interfaces graphically or as raw IDL. Interfaces can also be defined by importing compiled Java classes, standard-format EJB-JAR files, or ActiveX type libraries.

Server-side component support

Jaguar provides support for several major component models, including:

Enterprise JavaBeans Jaguar supports Java components that follow the JavaSoft Enterprise JavaBean (EJB) specification, versions 1.0 and 1.1. An Enterprise JavaBean is a nonvisual, transactional component that is implemented in Java. Chapter 8, "Creating Enterprise JavaBean Components" describes how to create EJB components.
Java-CORBA Java CORBA components follow the CORBA component model and use standard CORBA interfaces for transaction management. Almost any Java class with non-visual behavior can be adapted to run as a Jaguar component. Chapter 12, "Creating CORBA-Java Components", describes Jaguar's Java component support in detail.
PowerBuilder NVO Components Using PowerBuilder 7.0 or later, you can create nonvisual objects (NVOs) that run natively in a Jaguar server as Jaguar components. You can also create NVO proxies for Jaguar components, then use the proxies in PowerBuilder client applications. For more information, see Building Internet and Enterprise Applications in the Enterprise Application Studio online books collection.
CORBA C++ Components Jaguar C++ components are C++ classes that contain methods with similar prototypes to the Jaguar component interface (the exact interface mapping complies with the CORBA specification for IDL/C++ language bindings).
Chapter 16, "Creating CORBA C++ Components", describes C++ component support in detail.
ActiveX Any nonvisual ActiveX component can be installed as a Jaguar component (though you may need to define an "adaptor," or wrapper class to handle methods that use unsupported parameter datatypes). Jaguar uses COM and ActiveX automation support to execute ActiveX component methods. Consequently, all Jaguar ActiveX components must support COM's automation interface (the IDispatch interface). Many application development tools, such as Microsoft Visual Basic, can be used to create ActiveX components that are compatible with Jaguar.
Chapter 19, "Creating ActiveX Components", describes Jaguar's ActiveX support in detail.

Jaguar implements subsets of the Microsoft Transaction Server (MTS) ActiveX interface with the goal of providing full compatibility in the future.
C Components Jaguar provides a C "pseudo" component model that can be used to adapt existing C procedural applications as Jaguar components. C components are dynamic link libraries (DLLs) or UNIX shared libraries that contain C or C++ methods and method skeletons. Method skeletons contain C functions that retrieve the RPC's parameters and invoke C component methods.
Appendix D, "Creating C Components", describes support for this component model.

C++ classes can be run as C++ components Developers using Jaguar version 1.1 may have adapted C++ classes to run as Jaguar C components. In version 2.0 and later, these classes can be run directly as C++ components.

Client stub/proxy support

Applications invoke a Jaguar component using a stub or proxy object. The stub or proxy acts as a local surrogate for the remote component; it provides the same method signatures as the component and hides the details of remote server communication. Stubs and proxies are available for:

Java (CORBA and EJB) Any component can be invoked via a Java stub class. Jaguar Manager generates source code for Java stubs. At runtime, your client program instantiates the stub. When you call methods on the stub class, the stub transparently invokes the component method on the Jaguar server. Using HTML pages, Java applets, and Jaguar's built-in HTTP support, you can create "zero-install" applications that have no client-machine installation requirements other than the presence of a Java-capable Web browser.
Jaguar supports three Java client models:
- EJB Your program uses the JavaSoft EJB (javax.ejb) classes and Jaguar's EJB stubs to call Jaguar component methods. This client model follows the EJB 1.1 Specification and is backward compatible with the EJB 1.0 specification. Chapter 9, "Creating Enterprise JavaBean Clients", describes how to implement EJB clients.
- Java-CORBA Your program uses Jaguar's CORBA-compliant Java ORB or any other CORBA-compliant Java ORB to instantiate stubs. Stub method signatures are mapped from the component's interface definition, based on the CORBA specification of IDL-Java language bindings. Chapter 13, "Creating CORBA-Compatible Java Clients", describes how to implement CORBA-Java clients.
- Jaguar 1.1 Your program uses the Java client interface that was defined in Jaguar version 1.1. This interface is obsolete but is provided for backward compatibility with Java clients that were developed for Jaguar 1.1. See Appendix C, "Creating Jaguar 1.1 Java Clients", for more information.
PowerBuilder PowerBuilder 7.0 or later allows you to generate NVOs that act as proxies for Jaguar components. Using the proxy, you can call component methods as if they were implemented as local NVO methods. See the PowerBuilder documentation for more information.
C++ (CORBA) Your program uses Jaguar's CORBA-compliant C++ ORB or any other CORBA-compliant C++ ORB to instantiate stubs. Stub method signatures are mapped from the component's interface definition, based on the CORBA specification of IDL-C++ language bindings. Chapter 17, "Creating CORBA C++ Clients", describes how to implement C++ clients.
ActiveX Your program invokes Jaguar components using Jaguar's ActiveX proxy. The ActiveX proxy allows you to invoke Jaguar components from ActiveX-enabled visual builder tools such as Microsoft Visual Basic. Used on the server, the ActiveX proxy allows you to invoke any Jaguar component from an ActiveX component. Jaguar Manager generates the type-library information that is required to register the component interface with your development tool. The ActiveX proxy uses the Jaguar C++ client ORB to communicate with Jaguar servers. Chapter 20, "Creating ActiveX Clients", describes how to use the ActiveX proxy.
Methods As Stored Procedures (MASP) Jaguar provides a built-in interface that allows you to execute component methods as if they were stored procedures in a Sybase Adaptive Server™ Enterprise database. This interface can be used to call Jaguar components from scripting and user-interface-builder tools that are database-aware but that do not support ActiveX. Appendix A, "Executing Methods As Stored Procedures", describes how to use this client interface.