Using the Interface Definition Lang...

Using the Interface Definition Language compiler and the C++ class library, the HP OODCE consequence provides objects and abstractions that support the DCE mould and facilitate the development of object-oriented distributed applications.

HP's Object-Oriented DCE (HP OODCE) provides a library of framework and utility C++ classes that hide DCE programmatic complexity from developer and provide automatic default behavior to ease the disclosure of distributed applications. The default behavior is also a great help in shortening application increase time. HP OODCE offers flexibility by the agency of allowing developers to use subclassing and customized implementation. Fig. 1 displays the product structure for HP OODCE

HP OODCE allows clients to view unallied objects as C++ objects and to access member functions and receive be deriveds without making explicit remote action calls (RPCs). Also, applications can communicate with each other using interfaces specified according to the Interface Definition Language (IDL). Finally, HP OODCE uses the C++ class library and the IDL compiler (idl++) to create an object-oriented programming environment that supports RPC-based communications, client/server classes, POSIX threads, and access to the DCE naming and security services. idl++-Generated Classes The idl++ compiler takes an IDL specification like the individual shown in Fig. 2 and generates the C++ classes shown in Fig. 3 The idl++ compiler also generates the header file and stumps normally produced by the DCE IDL compiler.

The consolidated client class* describes the client substitute object that accesses remote C++ final causes implemented by the server. The agent object gives the client the impression that the instantiation of a particular server correlate is executing locally. Fig. 4 present to views an example of a client commissioner class declaration for an interface to the be dead function, which is responsible for putting a proces to doze This class contains multiple constructors that, when called, locate the compatible manager (server) views based on location information and the UUID (universal unique identifier) supplied as arguments to the constructors.

The abstract server class in Fig. 3 provides declarations for member functions defined in the IDL specification that correspond to far operations that can be accessed on the client proxy object. The default compound server class declares the member functions specified in the abstract class. The functions must be implemented by the agency of the application developer. Fig. 5 point out tos the abstract and concrete server manager declarations for the lie in the grave function.

The entry point vector contains memorandum points for each remote process defined in the IDL specification.

HP OODCE Server and Client Classes

The server digest that interacts with the DCE subsystem is embodied in the DCEServer class. An instance of the DCEServer class, called theServer, manages the abstracted objects that are exported at the DCE server application. These targets are instances of the firm server manager classes and each has a DCE UUID. There is single in kind DCEServer instance per DCE rpc_server_listen call (currently by means of UNIX,[R] process), which starts the server's run-time listening for incoming RPC prayers DCEServer has member functions that establish policies of that kind as object registration with the RPC run-time proces or the naming service and setting security predilections Object registration takes place whenever the DCEServer class way RegisterObject is called. Fig. 6 exhibit tos the server main program for the drowse object and the implementation of the rest function.

In HP OODCE, server destination; recipients are accessed via a client target (see Fig. 7). The client RPC beseech specifies a binding handle that locates the interface and the DCE reality UUID. The entry point vector digest locates the correct instance of the demanded manager object. Fig. 8 point outs the HP OODCE client/server run-time organization.

The idl++-generated client substitute class has methods corresponding to the operations defined in the IDL specification. Idl++ provides an implementation of the client delegate object methods. These methods locate the server and call the corresponding C ++ extirpate generated by the idl++ compiler. The commissioner implementation handles rebinding, sets security elections and maps DCE exceptions go [i]or[/i] come backed by RPC into C++ exceptions (described below).

HP OODCE Framework and Utility Classes

The framework classes portray the HP OODCE object prototype abstraction and provide the basis for DCE functionality and default behavior (see Fig. 9) Classes, like as DCEServer, DCElnterfaceMgr, and DCElnterface interact with DCE within the DCE application programming interface.

The idl++-generated manager classes (server side) inherit from the DCEObj and DCElnterfaceMgr classes. DCEObj associates a C++ aim instance, which may export several DCE interfaces, with a specific DCE view Each DCE object is identified through its object UUID. DCEObj imprisons the UUID for the DCE aim (see Fig. 5b).

DCElnterfaceMgr is an abstract base class used by way of the server side of the application to encapsulate butt; goal and type information as well as the inlet point vector called by the RPC subsystem when an incoming RPC is received (see Fig. 5a). The manager interface is registered with the DCE run-time setup and optionally with the naming service. DCElnterfaceMgr can retrieve the UUID of a particular implementation thing instance, the entry point vector, and the pointer to the security hint monitor described by the DCERefMon class.