.if false ================================================================================== Copyright (c) 2019-2020 Nokia Copyright (c) 2018-2020 AT&T Intellectual Property. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ================================================================================== .fi .ix pause &h1(Appendix &gloss_appendix -- Glossary) Many terms in networking can be interpreted with multiple meanings, and several terms used in various RMR documentation are RMR specific. The following definitions are the meanings of terms used within RMR documentation and should help the reader to understand the intent of meaning. &beg_dlist( &1.0i Helvetica-bold : : 25,70 ) &ditem(application) A programme which uses RMR to send and/or receive messages to/from another RMR based application. &ditem(Critical error) An error that RMR has encountered which will prevent further successful processing by RMR. Critical errors usually indicate that the application should abort. &ditem(Endpoint) An RMR based application that is defined as being capable of receiving one or more types of messages (as defined by a &ital(message key.) .sm ) &ditem(Environment variable) A key/value pair which is set externally to the application, but which is available to the application (and referenced libraries) through the &cw(getenv) system call. Environment variables are the main method of communicating information such as port numbers to RMR. &ditem(Error) An abnormal condition that RMR has encountered, but will not affect the overall processing by RMR, but may impact certain aspects such as the ability to communicate with a specific endpoint. Errors generally indicate that something, usually external to RMR, must be addressed. &ditem(Host name) The name of the host as returned by the &cw(gethostbyname) system call. In a containerised environment this might be the container or service name depending on how the container is started. From RMR's point of view, a host name can be used to resolve an &ital(endpoint) definition in a &ital(route table.) &ditem(IP) Internet protocol. A low level transmission protocol which governs the transmission of datagrams across network boundaries. &ditem(Listen socket) A &ital(TCP) socket used to await incoming connection requests. Listen sockets are defined by an interface and port number combination where the port number is unique for the interface. &ditem(Message) A series of bytes transmitted from the application to another RMR based application. A message is comprised of RMR specific data (a header), and application data (a payload). &ditem(Message buffer) A data structure used to describe a message which is to be sent or has been received. The message buffer includes the payload length, message type, message source, and other information. &ditem(Messgae type) A signed integer (0-32000) which identifies the type of message being transmitted, and is one of the two components of a &ital(routing key.) See &ital(Subscription ID.) &ditem(Payload) The portion of a message which holds the user data to be transmitted to the remote &ital(endpoint.) The payload contents are completely application defined. &ditem(RMR context) A set of information which defines the current state of the underlying transport connections that RMR is managing. The application will be give a context reference (pointer) that is supplied to most RMR functions as the first parameter. &ditem(Round robin) The method of selecting an &ital(endpoint) from a list such that all &ital(endpoints) are selected before starting at the head of the list. &ditem(Route table) A series of "rules" which define the possible &ital(endpoints) for each &ital(message key.) &ditem(Route table manager) An application responsible for building a &ital(route table) and then distributing it to all applicable RMR based applications. &ditem(Routing) The process of selecting an &ital(endpoint) which will be the recipient of a message. &ditem(Routing key) A combination of &ital(message type) and &ital(subscription ID) which RMR uses to select the destination &ital(endpoint) when sending a message. &ditem(Source) The sender of a message. &ditem(Subscription ID) A signed integer value (0-32000) which identifies the subscription characteristic of a message. It is used in conjunction with the &ital(message type) to determine the &ital(routing key.) &ditem(Target) The &ital(endpoint) selected to receive a message. &ditem(TCP) Transmission Control Protocol. A connection based internet protocol which provides for lossless packet transportation, usually over IP. &ditem(Thread) Also called a &ital(process thread, or pthread.) This is a lightweight process which executes in concurrently with the application and shares the same address space. RMR uses threads to manage asynchronous functions such as route table updates. &Term(Trace information) An optional portion of the message buffer that the application may populate with data that allows for tracing the progress of the transaction or application activity across components. RMR makes no use of this data. &ditem(Transaction ID) A fixed number of bytes in the &ital(message buffer) which the application may populate with information related to the transaction. RMR makes use of the transaction ID for matching response messages with the &c(rmr_call) function is used to send a message. &ditem(Transient failure) An error state that is believed to be short lived and that the operation, if retried by the application, might be successful. C programmers will recognise this as &cw(EAGAIN.) &ditem(Warning) A warning occurs when RMR has encountered something that it believes isn't correct, but has a defined work round. &ditem(Wormhole) A direct connection managed by RMR between the user application and a remote, RMR based, application. &end_dlist .ix resume