Chaos RTAPE protocol - Revision history

Jnc: Avoid redir; add some links

2025-04-19T14:05:55Z

Avoid redir; add some links

Jnc: Avoid redir

2025-04-12T17:53:23Z

Avoid redir

Larsbrinkhoff: Category: Network Application Protocols

2024-07-30T06:07:00Z

Category: Network Application Protocols

Larsbrinkhoff: /* Status information */

2024-04-11T18:29:47Z

‎Status information

Larsbrinkhoff: /* Status information */ Updates from Heinz-Bernd Eggenstein.

2024-04-11T18:26:49Z

‎Status information: Updates from Heinz-Bernd Eggenstein.

Jnc: Better cat

2023-12-12T16:03:48Z

Better cat

Jnc: Jnc moved page Chaosnet RTAPE protocol to Chaos RTAPE protocol without leaving a redirect: Chaos confusion fix

2023-12-12T16:01:41Z

Jnc moved page Chaosnet RTAPE protocol to Chaos RTAPE protocol without leaving a redirect: Chaos confusion fix

Larsbrinkhoff: Add a little more information.

2023-09-22T05:10:00Z

Add a little more information.

Larsbrinkhoff: A fabulous start.

2023-09-21T17:39:53Z

A fabulous start.

New page

The [[Chaosnet]] '''RTAPE''' [[protocol]] is used to provide a remote [[Magnetic tape|tape]] [[server]] on a Chaos [[network]]. The protocol is structured as a sequence of messages called a ''record stream'', and each message specifies an operation to be performed or data to transmit.

A description of the protocol—as reverse engineered from ITS' DUMP backup program and the [[MIT]]/[[Symbolics]] RTAPE.c server for [[BSD]] [[Unix]]—follows.

===Record stream===

Once a connection has been established, the server sends a packet with the string <code>RECORD STREAM VERSION 1</code>. The client responds with the same string. Presumably the parties can negotiate another version, but so far only version 1 is known.

After that, both sides will exchange messages. Each message begins with an octet which is the opcode. After that comes two octets, in big-endian order, which is the size of the data that follows. Finally come as many octets of data as specified by the size.

The data portion may be an ASCII text string, or binary data to transmit tape blocks.

===Operations===

Client-to-server opcodes:
{| class="wikitable"
! Opcode || Name || Data
|-
| 1 || Login || ?
|-
| 2 || Mount || Text: type reel drive size density options
|-
| 3 || Probe || Binary: two octets with an ID
|-
| 4 || Read || Nothing (read all records until file mark),<br>or text: number-of-records
|-
| 5 || Write || Text: block-size (decimal)
|-
| 6 || Rewind || Nothing
|-
| 7 || Rewind-sync || Nothing
|-
| 8 || Rewind-unload || Nothing
|-
| 9 || Space file || Text: number-of-files
|-
| 10 || Space record || Text: number-of-records
|-
| 12 || Write file mark || Nothing
|-
| 13 || Close || Nothing
|}

Server-to-client opcodes:
{| class="wikitable"
! Opcode || Name || Data
|-
| 33 || Login response || ?
|-
| 34 || Read data || Binary: tape block data
|-
| 35 || Read file mark || Nothing
|-
| 36 || Status || See below
|}

<code>Status</code> messages may be solicited by the <code>Probe</code> opcode, or the server can send them at any time to signal an error.

The <code>Read</code> operation may transmit several tape blocks, but the client can interrupt this at any time by sending a <code>Probe</code>.

===Status information===

The <code>Status</code> message has this data:

{| class="wikitable"
! Offset || Size || Description || Data
|-
| 0 || 1 || Version || Only <code>1</code> is known
|-
| 1 || 2 || ID || Matching the <code>Probe</code> ID (''Solicited'' flag set),<br>or <code>0</code>
|-
| 3 || 3 || Number of blocks read ||
|-
| 6 || 3 || Number of blocks skipped ||
|-
| 9 || 3 || Number of blocks discarded ||
|-
| 12 || 1 || Last operation received ||
|-
| 13 || 2 || Density ||
|-
| 15 || 2 || Retries in last operation ||
|-
| 17 || 1 || Length of next string ||
|-
| 18 || ''n'' || Name of drive ||
|-
| 18+''n'' || 2 || Flags ||
|-
| 20+''n'' || ? || Optional error message ||
|}

The two-octet flags field, when taken as a little-endian number:
{| class="wikitable"
! Bit || Description
|-
| 0 || Solicited, e.g. requested by <code>Probe</code>
|-
| 1 || Drive is at beginning of tape
|-
| 2 || Drive is past end of tape
|-
| 3 || Last operation reached a file mark
|-
| 4 || Not logged in
|-
| 5 || Tape is mounted
|-
| 6 || Error message follows
|-
| 7 || Hard error
|-
| 8 || Soft error
|-
| 9 || Drive is offline
|}

[[Category:Network Protocols]]

@@ Line 1: / Line 1: @@
-The [[Chaosnet|Chaos]] '''RTAPE''' [[protocol]] is used to provide a remote [[magnetic tape|tape]] [[server]] on a Chaos [[network]].  The protocol is structured as a sequence of messages called a ''record stream'', and each message specifies an operation to be performed or data to transmit.
+The [[Chaosnet|Chaos]] '''RTAPE''' [[protocol]] is used to provide a remote [[magnetic tape|tape]] [[server]] on a Chaos [[data network|network]].  The protocol is structured as a sequence of messages called a ''record stream'', and each message specifies an operation to be performed or data to transmit.
-A description of the protocol&mdash;as reverse engineered from ITS' DUMP backup program and the [[Massachusetts Institute of Technology|MIT]]/[[Symbolics]] RTAPE.c server for [[BSD]] [[Unix]]&mdash;follows.
+A description of the protocol&mdash;as reverse engineered from ITS' DUMP backup program and the [[Massachusetts Institute of Technology|MIT]]/[[Symbolics]] RTAPE.c server for [[BSD]] [[UNIX|Unix]]&mdash;follows.
 ===Record stream===
-Once a connection has been established, the server sends a packet with the string <code>RECORD STREAM VERSION 1</code>.  The client responds with the same string.  Presumably the parties can negotiate another version, but so far only version 1 is known.
+Once a [[connection]] has been established, the server sends a [[packet]] with the string <code>RECORD STREAM VERSION 1</code>.  The client responds with the same string.  Presumably the parties can negotiate another version, but so far only version 1 is known.
-After that, both sides will exchange messages.  Each message begins with an octet which is the opcode.  After that comes two octets, in big-endian order, which is the size of the data that follows.  Finally come as many octets of data as specified by the size.
+After that, both sides will exchange messages.  Each message begins with an [[octet]] which is the opcode.  After that comes two octets, in [[big-endian]] order, which is the size of the data that follows.  Finally come as many octets of data as specified by the size.
-The data portion may be an ASCII text string, or binary data to transmit tape blocks.  If text data has several fields, they are separated by a space characters; numbers are in decimal with an optional minus sign.
+The data portion may be an [[ASCII]] text string, or binary data to transmit tape blocks.  If text data has several fields, they are separated by space characters; numbers are in decimal with an optional minus sign.
 ===Operations===

@@ Line 1: / Line 1: @@
 The [[Chaosnet|Chaos]] '''RTAPE''' [[protocol]] is used to provide a remote [[magnetic tape|tape]] [[server]] on a Chaos [[network]].  The protocol is structured as a sequence of messages called a ''record stream'', and each message specifies an operation to be performed or data to transmit.
-A description of the protocol&mdash;as reverse engineered from ITS' DUMP backup program and the [[MIT]]/[[Symbolics]] RTAPE.c server for [[BSD]] [[Unix]]&mdash;follows.
+A description of the protocol&mdash;as reverse engineered from ITS' DUMP backup program and the [[Massachusetts Institute of Technology|MIT]]/[[Symbolics]] RTAPE.c server for [[BSD]] [[Unix]]&mdash;follows.
 ===Record stream===

← Older revision		Revision as of 06:07, 30 July 2024
Line 134:		Line 134:

	[[Category: Chaos]]		[[Category: Chaos]]
		+	[[Category: Network Application Protocols]]

@@ Line 101: / Line 101: @@
 | 17 || 1 || Length of drive name ||
 |-
-| 18-33 || 16 || Name of drive ||
+| 18 || 16 || Name of drive ||
 |-
 | 34 || 2 || Flags ||

@@ Line 1: / Line 1: @@
-The [[Chaosnet]] '''RTAPE''' [[protocol]] is used to provide a remote [[Magnetic tape|tape]] [[server]] on a Chaos [[network]].  The protocol is structured as a sequence of messages called a ''record stream'', and each message specifies an operation to be performed or data to transmit.
+The [[Chaosnet|Chaos]] '''RTAPE''' [[protocol]] is used to provide a remote [[magnetic tape|tape]] [[server]] on a Chaos [[network]].  The protocol is structured as a sequence of messages called a ''record stream'', and each message specifies an operation to be performed or data to transmit.
 A description of the protocol&mdash;as reverse engineered from ITS' DUMP backup program and the [[MIT]]/[[Symbolics]] RTAPE.c server for [[BSD]] [[Unix]]&mdash;follows.
@@ Line 133: / Line 133: @@
 |}
-[[Category:Network Protocols]]
+[[Category: Chaos]]

@@ Line 99: / Line 99: @@
 | 15 || 2 || Retries in last operation ||
 |-
-| 17 || 1 || Length of next string ||
+| 17 || 1 || Length of drive name ||
 |-
-| 18 || ''n'' || Name of drive ||
+| 18-33 || 16 || Name of drive ||
 |-
-| 18+''n'' || 2 || Flags ||
+| 34 || 2 || Flags ||
 |-
-| 20+''n'' || ? || Optional error message ||
+| 36 || ? || Optional error message ||
 |}

← Older revision	Revision as of 16:01, 12 December 2023
(No difference)