The LDM 6 Protocol


This page describes the various RPC messages used by the LDM 6 protocol.

Contents


General Information

Item Value
RPC Program # 300029
Well-Known Port # 388


Individual RPC Messages

FEEDME

A FEEDME message is sent by a downstream LDM 6 to its upstream LDM 6 to request all data-products that match the data-product selection-criteria specified in the message. The message also specifies the maximum HEREIS size.

NOTIFYME

A NOTIFYME message is sent by a downstream LDM 6 to its upstream LDM 6 to request the data-product metadata of all data-products that match the data-product selection-criteria specified in the message.

NOTIFICATION

A NOTIFICATION message is sent by an upstream LDM 6 to a downstream LDM 6 to deliver data-product metadata in response to a NOTIFYME request from the downstream LDM 6.

HEREIS

A HEREIS message is sent by an upstream LDM 6 to a downstream LDM 6 to deliver a data-product whose data-product size is less than or equal to the maximum HEREIS size specified by the downstream LDM 6.

COMINGSOON

A COMINGSOON message is sent by an upstream LDM 6 to a downstream LDM 6 to deliver the data-product metadata of a data-product whose data-product size is greater than the maximum HEREIS size specified by the downstream LDM 6. This synchronous message implicitly asks if the downstream LDM 6 wants the specified data-product. The data-product will be delivered in a subsequent BLKDATA message if and only if the downstream LDM 6 replies affirmatively.

BLKDATA

A BLKDATA message is sent by an upstream LDM 6 to a downstream LDM 6 to deliver the data-product whose data-product metadata was contained in the previous COMINGSOON message.

HIYA

A HIYA message is sent, unsolicited, by an upstream LDM 6 to a downstream LDM 6 to specify the data-product selection-criteria that the upstream LDM 6 will use to send data-products to the downstream LDM 6.

IS_ALIVE

An IS_ALIVE message is sent by a downstream LDM to the top-level ldmd on the upstream host when the downstream LDM hasn't received anything in 60 seconds. The purpose of the message is to inquire whether or not the relevant upstream LDM is still running.