Connection Initialization
Once a connection has been established between a client and server, a short
synchronous handshake initiates the rad protocol. The server begins by sending a SERVER-HELLO
message. This message specifies the minimum and maximum protocol versions (inclusive) recognized by the
server.
Table A-33 SERVER-HELLO
|
|
|
|
|---|
protocol |
3 |
string[3] |
“RAD” |
min_ver |
4 |
int |
Minimum supported version |
max_ver |
4 |
int |
Maximum supported version |
|
The client then replies with a CLIENT-HELLO message specifying the version it wishes
to use. This version may not be less than the server's minimum version
or greater than the server's maximum version.
Table A-34 CLIENT-HELLO
|
|
|
|
|---|
protocol |
3 |
string[3] |
“RAD” |
version |
4 |
int |
Client-selected version |
locale |
Varies |
string<256> |
Client locale
|
|
Part of the rad protocol is the communication of structured error data on
request failures. For consistency with the object-specific errors that server-side objects are permitted
to return, the errors returned by rad when requests fail for other reasons
are also defined using ADR. After the server receives and accepts a CLIENT-HELLO
message, it replies with ERRORS to communicate those type definitions.
Table A-35 ERRORS
|
|
|
|
|---|
error_space |
Varies |
TYPESPACE |
Typespace containing error
types |
errors |
Varies |
TYPEREF<> |
Error types, starting with EC-NOMEM |
|
The TYPEREFs refer to the types defined in the error_space TYPESPACE. The types
define the first error_count errors, starting from the first non object-specific error, EC-NOMEM.
Any errors for which types are not defined have type void.
At this point, the handshake is complete and normal client-server communication can occur.
