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This section provides general information about SCSP INFO that applies to both named and unnamed objects.

Table of Contents
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INFO is a request to the storage cluster to provide information about a specific object. The INFO message is identical in semantics to the READ request, except that the object (if found) is not returned in the response. If the referenced content is found in the cluster, only the meta-information about that object is returned in the form of response headers. The INFO request is formatted as a simple HTTP request using the HEAD method.

SCSP Method

HTTP Method

RFC 7231 Section

INFO

HEAD

4.3.2


title
Info

Note

SCSP allows HEAD requests with mismatched Accept-Encoding headers to receive responses as if the encoding matched that of the object. Swarm  Swarm relaxed this RFC restriction because a because a HEAD request returns no body contents, so there is nothing to encode. 

INFO for named objects

Code Block
languagexml
HEAD /mybucket/samplefile.txt HTTP/1.1
  Host: cluster.example.com
  User-Agent: Swarm Client/0.1

...

Normal responses to INFO

See SCSP Headers for a list of response headers.

The responses described in this section might be returned by the storage cluster in the case where the requested content was found. The content's meta-information can be returned directly by the node that received the request or the request might be redirected to another node in the cluster.

title
Info

Note

If you add ?checkIntegrity to HEAD and GET requests for the same object, different Content-Length values in the responses will display. This occurs because the HEAD response returns the Content-Length of the manifest rather than the object.

The following response indicates that the requested object was located, but that another node in the cluster will service the request for meta-information. Additionally, all future requests of this storage cluster should be made through the new access node until another 301 response is received. There is no message-body, so the content length is always 0. The value of the Location header indicates which node in the cluster should receive the redirect.

301 Moved Permanently

The client is expected to send another INFO request using the exact URI contained in the Location header.

Code Block
languagexml
HTTP/1.1 301 Moved Permanently
  Date: Wed, 1 Sept 2010 15:59:02 GMT
  Server: CAStor Cluster/v8b2
  Connection: close
  Location: http://node-ip/name-or-uuid?auth=2096EFA659295BBB819D1FECCE77D2EF
  Content-Length: 0

307 Temporary Redirect

The following response (307) is similar to the 301 response, except the client should continue to use the current node (the one generating this response) for future requests until further notice.

Code Block
languagexml
HTTP/1.1 307 Temporary Redirect
  Date: Wed, 1 Sept 2010 15:59:02 GMT
  Server: CAStor Cluster/5.0.0
  Location: http://node-ip/name-or-uuid?auth=2096EFA659295BBB819D1FECCE77D2EF
  Content-Length: 0

Normal responses for named objects

Code Block
languagexml
INFO response for a named object in a domain:
HTTP/1.1 401 Unauthorized
  WWW-Authenticate: Digest realm="cluster.example.com/_administrators", 
  nonce="05d0a60ee1f44361f449496505e05116", opaque="fd9c8e14e20fb7c13408c049b7d222af",     `
  stale=false,   `
  qop="auth",   `
  algorithm=MD5
  WWW-Authenticate: Basic realm="cluster.example.com/_administrators"
  Content-Length: 51
  Content-Type: text/html
  Date: Sat, 16 Oct 2010 00:23:24 GMT
  Server: CAStor Cluster 5.0.0
  Allow: HEAD, GET, PUT, POST, COPY, APPEND, DELETE
HTTP/1.1 200 OK
  Castor-System-Alias: ec87e3c7c410cc04fc4c838061898d9c
  Castor-System-CID: ffffffffffffffffffffffffffffffff
  Castor-System-Cluster: cluster.example.com
  Castor-System-Created: Fri, 15 Oct 2010 23:59:40 GMT
  Castor-System-Name: cluster.example.com
  Castor-System-Owner: admin@CAStor administrator
  Castor-System-Version: 1287187180.959
  Content-Length: 0
  Last-Modified: Fri, 15 Oct 2010 18:35:56
  GMT lifepoint: [] reps=16
  Etag: "da8bfbb04d089b9c22ae77747f327233"
  Date: Sat, 16 Oct 2010 00:23:24 GMT
  Server: CAStor Cluster/5.0.0

The initial 401 Unauthorized response is a normal initial response to HTTP authentication. Because access to a domain always requires administrator credentials, you will always see an initial 401 on an INFO on a domain.

Code Block
languagexml
HTTP/1.1 200 OK
  Castor-System-Alias: d36dfca69ba7752f4708b1fa9bf9918b
  Castor-System-CID: ec87e3c7c410cc04fc4c838061898d9c
  Castor-System-Cluster: cluster.example.com
  Castor-System-Created: Fri, 15 Oct 2010 18:36:05 GMT
  Castor-System-Name: bucket
  Castor-System-Version: 1287167765.255
  Content-Length: 0
  Content-Type: application/x-www-form-urlencoded
  Last-Modified: Fri, 15 Oct 2010 18:36:05 GMT
  Etag: "21641b39f4fdc1e86dc67e798a320980"
  Date: Fri, 15 Oct 2010 23:54:44 GMT
  Server: CAStor Cluster/5.0.0
HTTP/1.1 200 OK
  Castor-System-CID: d36dfca69ba7752f4708b1fa9bf9918b
  Castor-System-Cluster: cluster.example.com
  Castor-System-Created: Fri, 15 Oct 2010 22:09:19 GMT
  Castor-System-Name: file.txt
  Castor-System-Version: 1287180559.436
  Content-Length: 26
  Content-Type: application/x-www-form-urlencoded
  Last-Modified: Fri, 15 Oct 2010 22:09:19 GMT
  Etag: "c744aa90d375aa3e1f228f74b7960e54"
  Date: Fri, 15 Oct 2010 23:51:44 GMT
  Server: CAStor Cluster/5.0.0

The response for a named object is very similar to the response for a bucket except that Castor-System-CID is the identifier of the named object's parent (the bucket).

Normal responses for unnamed objects

The following response indicates that the node that received the request found the requested content and is returning meta-information about the object in the headers of this response.

Code Block
languagexml
HTTP/1.1 200 OK
  Date: Wed, 1 Sept 2010 15:59:02 GMT
  Server: CAStor Cluster/5.0.0
  Content-Type: image/jpeg
  Content-Length: (length of the content of the Swarm object) 
  Replica-Count: (number of replicas in cluster)
  [ application-meta-information ]

Error responses to INFO

The responses in this section may be returned by the storage cluster when the specified content cannot be found or there is a problem with the INFO request.

The following response indicates a problem with the INFO request, such as missing mandatory headers, invalid message body, or any other violation of HTTP/1.1 by the HEAD request. The reason for the error is included in the status line.

Code Block
languagexml
HTTP/1.1 400 Bad Request
  Date: Wed, 1 Sept 2010 15:59:02 GMT
  Server: CAStor Cluster 5.0.0
  Content-Length: 24
  Content-Type: text/html

Indicates that the requested object could not be located in this cluster:

Code Block
languagexml
HTTP/1.1 404 Not Found
  Date: Wed, 1 Sept 2010 15:59:02 GMT
  Server: CAStor Cluster 5.0.0
  Content-Length: 56
  Content-Type: text/html

 

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