NAME
globus_gram_protocol - GRAM Protocol Definition The GRAM Protocol is
used to handle communication between the Gatekeeper, Job Manager, and
GRAM Clients.
The protocol is based on a subset of the HTTP/1.1 protocol, with a
small set of message types and responses sent as the body of the HTTP
requests and responses. This document describes GRAM Protocol version
2.
Framing
GRAM messages are framed in HTTP/1.1 messages. However, only a small
subset of the HTTP specification is used or understood by the GRAM
system. All GRAM requests are HTTP POST messages. Only the following
HTTP headers are understood:
· Host
· Content-Type (set to ’application/x-globus-gram’ in all cases)
· Content-Length
· Connection (set to ’close’ in all HTTP responses)
Only the following status codes are supported in response’s HTTP
Status-Lines:
· 200 OK
· 403 Forbidden
· 404 Not Found
· 500 Internal Server Error
· 400 Bad Request
Message Format
All messages use the carriage return (ASCII value 13) followed by line
feed (ASCII value 10) sequence to delimit lines. In all cases, a blank
line separates the HTTP header from the message body. All
application/x-globus-gram message bodies consist of attribute names
followed by a colon, a space, and then the value of the attribute. When
the value may contain a newline or double-quote character, a special
escaping rule is used to encapsulate the complete string. This
encapsulation consists of surrounding the string with double-quotes,
and escaping all double-quote and backslash characters within the
string with a backslash. All other characters are sent without
modification. For example, the string
rsl: &( executable = ’/bin/echo’ )
( arguments = ’hello’ )
becomes
rsl: ’&( executable = ´bin/echo´ )
(arguments = ´hello´ )’
This is the only form of quoting which application/x-globus-gram
messages support. Use of % HEX HEX escapes (such as seen in URL
encodings) is not meaningful for this protocol.
Message Types
Ping Request
A ping request is used to verify that the gatekeeper is configured
properly to handle a named service. The ping request consists of the
following:
POST ping/job-manager-name HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
The values of the message-specific strings are
job-manager-name
The name of the service to have the gatekeeper check. The service
name corresponds to one of the gatekeeper’s configured grid-
services, and is usually of the form ’jobmanager-<em>scheduler-
type</em>’.
host-name
The name of the host on which the gatekeeper is running. This
exists only for compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
Job Request
A job request is used to scheduler a job remotely using GRAM. The ping
request consists of the HTTP framing described above with the request-
URI consisting of job-manager-name, where job-manager name is the name
of the service to use to schedule the job. The format of a job request
message consists of the following:
POST job-manager-name[@user-name] HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
job-state-mask: mask
callback-url: callback-contact
rsl: rsl-description
The values of the emphasized text items are as below:
job-manager-name
The name of the service to submit the job request to. The service
name corresponds to one of the gatekeeper’s configured grid-
services, and is usually of the form ’jobmanager-<em>scheduler-
type</em>’.
user-name
Starting with GT4.0, a client may request that a certain account by
used by the gatekeeper to start the job manager. This is done
optionally by appending the @ symbol and the local user name that
the job should be run as to the job-manager-name. If the @ and
username are not present, then the first grid map entry will be
used. If the client credential is not authorized in the grid map to
use the specified account, an authorization error will occur in the
gatekeeper.
host-name
The name of the host on which the gatekeeper is running. This
exists only for compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
mask
An integer representation of the job state mask. This value is
obtained from a bitwise-OR of the job state values which the client
wishes to receive job status callbacks about. These meanings of the
various job state values are defined in the GRAM Protocol API
documentation.
callback-contact
A https URL which defines a GRAM protocol listener which will
receive job state updates. The from a bitwise-OR of the job state
values which the client wishes to receive job status callbacks
about. The job status update messages are defined below.
rsl-description
A quoted string containing the RSL description of the job request.
Status Request
A status request is used by a GRAM client to get the current job state
of a running job. This type of message can only be sent to a job
manager’s job-contact (as returned in the reply to a job request
message). The format of a job request message consists of the
following:
POST job-contact HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
’status’
The values of the emphasized text items are as below:
job-contact
The job contact string returned in a response to a job request
message, or determined by querying the MDS system.
host-name
The name of the host on which the job manager is running. This
exists only for compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
Callback Register Request
A callback register request is used by a GRAM client to register a new
callback contact to receive GRAM job state updates. This type of
message can only be sent to a job manager’s job-contact (as returned in
the reply to a job request message). The format of a job request
message consists of the following:
POST job-contact HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
’register <em>mask</em> <em>callback-contact</em>’
The values of the emphasized text items are as below:
job-contact
The job contact string returned in a response to a job request
message, or determined by querying the MDS system.
host-name
The name of the host on which the job manager is running. This
exists only for compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
mask
An integer representation of the job state mask. This value is
obtained from a bitwise-OR of the job state values which the client
wishes to receive job status callbacks about. These meanings of the
various job state values are defined in the GRAM Protocol API
documentation.
callback-contact
A https URL which defines a GRAM protocol listener which will
receive job state updates. The from a bitwise-OR of the job state
values which the client wishes to receive job status callbacks
about. The job status update messages are defined below.
Callback Unregister Request
A callback unregister request is used by a GRAM client to request that
the job manager no longer send job state updates to the specified
callback contact. This type of message can only be sent to a job
manager’s job-contact (as returned in the reply to a job request
message). The format of a job request message consists of the
following:
POST job-contact HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
’unregister <em>callback-contact</em>’
The values of the emphasized text items are as below:
job-contact
The job contact string returned in a response to a job request
message, or determined by querying the MDS system.
host-name
The name of the host on which the job manager is running. This
exists only for compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
callback-contact
A https URL which defines a GRAM protocol listener which should no
longer receive job state updates. The from a bitwise-OR of the job
state values which the client wishes to receive job status
callbacks about. The job status update messages are defined below.
Job Cancel Request
A job cancel request is used by a GRAM client to request that the job
manager terminate a job. This type of message can only be sent to a job
manager’s job-contact (as returned in the reply to a job request
message). The format of a job request message consists of the
following:
POST job-contact HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
’cancel’
The values of the emphasized text items are as below:
job-contact
The job contact string returned in a response to a job request
message, or determined by querying the MDS system.
host-name
The name of the host on which the job manager is running. This
exists only for compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
Job Signal Request
A job signal request is used by a GRAM client to request that the job
manager process a signal for a job. The arguments to the various
signals are discussed in the globus_gram_protocol_job_signal_t
documentation.
POST job-contact HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
’<em>signal</em>’
The values of the emphasized text items are as below:
job-contact
The job contact string returned in a response to a job request
message, or determined by querying the MDS system.
host-name
The name of the host on which the job manager is running. This
exists only for compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
signal
A quoted string containing the signal number and it’s parameters.
Job State Updates
A job status update message is sent by the job manager to all
registered callback contacts when the job’s status changes. The format
of the job status update messages is as follows:
POST callback-contact HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
job-manager-url: job-contact
status: status-code
failure-code: failure-code
The values of the emphasized text items are as below:
callback-contact
The callback contact string registered with the job manager either
by being passed as the callback-contact in a job request message or
in a callback register message.
host-name
The host part of the callback-contact URL. This exists only for
compatibility with the HTTP/1.1 protocol.
message-size
The length of the content of the message, not including the
HTTP/1.1 header.
version
The version of the GRAM protocol which is being used. For the
protocol defined in this document, the value must be the string
’2’.
job-contact
The job contact of the job which has changed states.
Proxy Delegation
A proxy delegation message is sent by the client to the job manager to
initiate a delegation handshake to generate a new proxy credential for
the job manager. This credential is used by the job manager or the job
when making further secured connections. The format of the delegation
message is as follows:
POST callback-contact HTTP/1.1
Host: host-name
Content-Type: application/x-globus-gram
Content-Length: message-size
protocol-version: version
’renew’
If a successful (200) reply is sent in response to this message, then
the client will procede with a GSI delegation handshake. The tokens in
this handshake will be framed with a 4 byte big-endian token length
header. The framed tokens will then be wrapped using the
GLOBUS_IO_SECURE_CHANNEL_MODE_SSL_WRAP wrapping mode. The job manager
will frame response tokens in the same manner. After the job manager
receives its final delegation token, it will respond with another
response message that indicates whether the delegation was processed or
not. This response message is a standard GRAM response message.
Note on Security Attributes
The following security attributes are needed to communicate with the
Gatekeeper:
· Authentication must be done using GSSAPI mutual authentication
· Messages must be wrapped with support for the delegation message.
When using Globus I/O, this is accomplished by using the the
GLOBUS_IO_SECURE_CHANNEL_MODE_GSI_WRAP wrapping mode.
Changes
2004-08-11 Added information about gridmap choosing