Route Connects 

If the connection should be established over SAProuters, the route information is sent as the first message. The information includes:

·        Eye catcher

·        Route information version

·        NI version

·        Operation mode

·        Route length

·        Total number of nodes on the route

·        Pointer to the next hop on the route

·        Number of remaining nodes

·        Route string

The field for the route string contains the whole route, inclusive all previous nodes. For each node, the hostname, service/port and the password is included, separated by null characters. The values for the service/port and the password field may be empty strings. As default port number the value 3299 is used.

In the connect phase, the NI layer converts the route string from the input format (see Route Strings) into this internal format.

The data structure for the message is as follows:

Offset	Size (bytes)	Description and Value
0x00	9	eye catcher ("NI_ROUTE\0")
0x09	1	route information version (current version: 2)
0x0a	1	NI version (current version: 36)
0x0b	1	total number of entries (value 2 to 255)
0x0c	1	talk mode (NI_MSG_IO: 0; NI_RAW_IO; 1; NI_ROUT_IO: 2), see Communication Modes.
0x0d	2	currently unused field
0x0f	1	number of rest nodes (remaining hops; value 2 to 255)
0x10	4	route length (integer value in net byte order)
0x14	4	current position as an offset into the route string (integer value in net byte order)
0x18	*	route string in ASCII

Route String Format

The internal format of the route string looks like following (ASCII characters):

<hostname node 1>\0<port node 1>\0<password node 1>\0<hostname node 2>\0 ...

where \0 means the null character.

Example of a connection to the OSS

"localhost\03300\0test\0sapserv3.wdf.sap-ag.de\0\0\0147.204.100.35\0sapdp01\0\0"

with

·        node 1: hostname = "localhost"; port = 3300; password = "test"

·        node 2: hostname = "sapserv3.wdf.sap-ag.de"; port = 3299 (def.); password = ""

·        node 3: host address = 147.204.100.35; service name = "sapdp01"; password = ""

After a SAProuter has received the route information, the next destination is extracted from the string. If the connect to the next destination is successful, the same route information is passed with an incremented current position and decremented number of remaining nodes.

The own hostname in the string is replaced by the address / hostname of the previous node. This mechanism allows following SAProuters still to extract the whole route. In addition, newer SAProuter will add a leading blank to the hostname.