Notes on Cell Administration

Establishing Intercell Communication

Establishing Intercell Communication

The information in this section supplements the information in the OSF DCE Administration Guide — Core Services, and describes how intercell communication should be configured in an HP-UX environment.

Communication between DCE cells is facilitated by the gdad daemon, which implements the Global Directory Agent (GDA). When a client in a local cell wants to access another cell that the local cell does not already recognize, the request is passed to gdad, which looks up and returns information about how to find the remote cell. This information is cached, so that gdad is not asked repeatedly for the same information.

gdad finds information about the remote cell by querying a Domain Name Service (DNS) database. DNS is not part of DCE; it is a widely used distributed naming service, implemented on HP-UX by the named daemon, and documented in named (1M) man page and in Internet RFCs 1032, 1033, 1034, and 1035.

These procedures describe configuring GDA so that it can find the DNS server or servers where cell information is stored, creating DNS “resource records” that describe the cells you want GDA to be able to locate, and establishing peer-to-peer trust between two cells.

Specifying DNS Servers that GDA Should Query

GDA must be told which DNS name servers (such as instances of named) to query for information about foreign cells. The name server at localhost is usually preferred, as only localhost provides recursive query service—if localhost doesn’t have the requested data, localhost will query other name servers until it either finds the requested data or exhausts the list of name servers that it knows about.

Using localhost reduces the requirement to keep GDA informed when name server configurations change, and allows GDA to always receive a response with a single query. In some environments, however, you may want to point GDA at a non-local server or servers, rather than at localhost.

gdad uses the following algorithm to identify which name server or name servers to query:

Planning and Configuring HP DCE 1.7

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HP UX DCE Software manual Establishing Intercell Communication, Specifying DNS Servers that GDA Should Query
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UX DCE Software specifications

HP UX DCE Software, or Hewlett-Packard UNIX Distributed Computing Environment, represents a significant tool in the realm of distributed system architecture. Designed primarily for enterprise environments, HP UX DCE enhances the reliability, scalability, and manageability of applications over diverse networked systems.

One of the main features of HP UX DCE is its ability to integrate various computing platforms, enabling seamless communication and resource sharing across distributed nodes. This facilitates the creation of complex applications that can operate on a multitude of systems, thus enhancing operational flexibility. DCE employs standardized interfaces, which means applications written for one platform can run on any other platform that supports DCE, promoting cross-platform compatibility.

In terms of technologies, HP UX DCE utilizes Remote Procedure Calls (RPC) as a core feature. This mechanism allows different applications to communicate and invoke procedures on remote systems as if they were local calls. Additionally, DCE includes a robust security model that incorporates Kerberos for authentication, ensuring that communication between nodes remains secure and protected against unauthorized access.

Another significant characteristic of HP UX DCE is its distributed file system, which allows for transparent file access across different machines. The DCE File System (DFS) provides a unified namespace and manages data replication and consistency across distributed storage resources. This reduces the complexity of data management and enhances data availability.

HP UX DCE also supports a variety of programming languages, making it accessible for developers accustomed to different coding environments. This versatility encourages widespread adoption and innovation, as developers can leverage existing skills to create distributed applications.

Furthermore, HP UX DCE is built for high availability, ensuring that critical applications remain responsive even in the face of hardware or network failures. Its inherent component redundancy and fault-tolerant architecture are designed to minimize downtime, which is essential for mission-critical applications in enterprise scenarios.

In conclusion, HP UX DCE Software provides a comprehensive framework for developing, deploying, and managing distributed applications. Its core features such as RPC support, a secure authentication mechanism, a robust file system, and cross-platform compatibility make it a vital resource for organizations aiming to leverage distributed computing effectively. As enterprises evolve, HP UX DCE stands out as an influential solution in the dynamic landscape of distributed environments.
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