Tonge, Rzepa, Yoshida, page 4

OMG, a consortium of industry software developers, prior to the advent of the Web^.3The central components of CORBA are the object request broker (ORB), which intercepts the call from a client and is responsible for finding an object which can implement the request, and the Interface Definition Language (IDL). After defining an object interface, which will allow client and server objects written in different languages to inter-operate across a network, the definition is put through an IDL compiler to produce translated output (stubs and skeletons) in the language of choice. These can be used link the client and server objects via the ORB (Object request broker). ORB's are typically commercially written standalone packages, to which potential server objects have been attached/registered and whose functionality is augmented by a range of additional user services. IDL's have been produced for Java, C, and C++. This allows communication either between the ORB's own objects or (via IIOP) objects attached to other ORBs. The combination of Java clients with CORBA-compliant servers. A rather different distributed, competitive but highly proprietary object model has been developed by Microsoft. Known as the Distributed Component Object Model (DCOM),³it can support many of the functions devised for CORBA.

The CGI method will survive for some time as a general Internet workhorse, as it requires no special functionality on the client. However, as we move into an era where process and data authentication become more important and perhaps even essential, we anticipate that the three distributed object systems RMI, CORBA and DCOM will each become increasingly important. Each will provide niche advantages in Intranet and Extranet environments such as complete Java solutions for new developments, compatibility with legacy systems, and major software and operating system compatibility.

Internet Security and Digital Object Signing.

The great flexibility of TCP/IP - the communications protocol whereby documents are downloaded from server to client in packets viamultiple computers over the Internet - means that a document or programcould in principle be intercepted in transit and modified by unauthorised persons. One solution to this problem known as Secure Sockets Layer (SSL)⁴ operates at the packet level to ensure security, but it does not carry information about the content or nature of the program. Java applets were originally devised as a solution to the issue of interchanging network-transportable programs. Applets were specified to operate inside a so-called security sandbox in order to prevent potential rogue actions on the user's computer system (e.g. reading or deleting files) by a hostile attacker. They are not allowed to make arbitrary network connections, only back to the server from which they were downloaded, and they cannot be used to read from or write files to the local browser machine. These limitations are now considered too restrictive for many distributed computing applications. With the release of Web browsers supporting Version 1.1 or 1.2 of the Java Development Kit, it has now become possible to allow trustedapplets the ability to work outside the sandbox restrictions.⁵Trusted applets are provided with a verifiable digital signature, authorised by a recognised third party Certification Authority. Both Netscape Navigator and Microsoft Internet Explorer can be used to recognise whether an applet has been digitally signed with a valid object signing certificate (Netscape Object Signing / Microsoft Authenticode).