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About Objects and Security

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Currently, DX Storage understands only one application-level protocol, the Simple Content Storage Protocol (SCSP), which is a subset of the Hypertext Transfer Protocol, HTTP/1.1 used by web servers and browsers. While it is possible that additional access protocols will be added to DX Storage in the future, HTTP is the only protocol supported for the URI at this time. A DX Storage cluster is addressed using either the DNS name or the IP address of one of the nodes in the cluster. It doesn't matter which node is addressed initially, as long as it is accessible to the application on the network. Of course, if the addressed node has failed, or is offline for some reason, your URI might need to change. Note that it is not necessary that the node named in the URI be the same one that actually stored the object in the first place because any node can be asked to retrieve any object stored on any other node in the cluster. For unnamed objects, the UUID of an object to be retrieved from a DX Storage cluster is specified in the last component of the URI as a string of 32 case-insensitive hexadecimal digits. The length of the UUID string must always be exactly 32 characters (any leading zeros must be included). When storing an object for the first time, obviously there is no UUID assigned yet. Therefore, a WRITE request in SCSP includes just the first two components of the URI. After the data has been transferred and stored, DX Storage generates and returns a new UUID to the application. 1.8. About Objects and Security Starting with DX Storage version 5.0, you can optionally use security with named and unnamed objects. You can, for example, enable only users in a particular security realm to make changes to an object and prevent any other users from changing the object. You can apply security to buckets and to named or unnamed objects. The following figure shows a simple example of using security. In the example, the user Joe has access to the docs bucket where he can create named objects and user Jim has access to the videos bucket. Neither Joe nor Jim can write named objects to any other domain in the cluster (cloud.com). 1.8.1. The Basics of DX Storage Security DX Storage's security model uses the standard two-part approach of: • Authentication: DX Storage uses standard Digest Access Authentication as discussed in RFC 2617 to create one-way cryptographic hash algorithms to obscure identity information over the Internet while allowing a client (for example, a web browser) and the DX Storage server to exchange enough information to consummate authentication. DX Storage validates user names and passwords from a security realm, which is discussed in the next section. • Authorization: Provided a user authenticates successfully, the user's privileges are derived from the authorization specification associated with the object the user attempts to access. The authorization specification is discussed in the next section. Copyright © 2010 Caringo, Inc. All rights reserved 5 Version 5.0 December 2010

Section	Page
DX Object Storage Application Guide	1
Table of Contents	3
Chapter 1. Introduction to DX Storage Objects	6
1.1. Introducing Named Objects	6
1.2. Summary of Named Objects and Unnamed Objects	7
1.3. Common Named Object Terminology	7
1.4. About DX Storage Object Types	8
1.5. Bucket and Object Naming Rules	8
1.6. Simple Examples of Creating Buckets and Named Objects	8
1.7. Universal Resource Identifiers (URIs)	9
1.8. About Objects and Security	10
1.8.1. The Basics of DX Storage Security	10
1.8.2. Commonly Used Security Terminology	11
1.8.3. Basic Security Guidelines	11
1.9. Concepts for Unnamed Objects	11
1.9.1. Universally Unique Identifiers (UUIDs)	11
1.9.2. About Immutable Objects	12
1.9.3. About Anchor Streams	12
1.10. Document Typographical Conventions	13
Chapter 2. Connecting to a DX Storage Cluster	14
2.1. About the Primary Access Node (PAN)	14
2.2. Requirements for Node Accessibility	14
2.2.1. Using the DX Storage Software Development Kit (SDK)	14
2.2.2. Using Multicast-DNS (mDNS)	15
2.2.3. Using DNS Round Robin	15
2.2.4. Using a Pool of Static IP Addresses	16
2.2.5. Using a Single Static IP Address	16
Chapter 3. Application Best Practices	17
3.1. Using the Software Development Kit (SDK)	17
3.2. Dynamically Locating DX Storage Nodes	17
3.3. Optimizing Bucket and Domain Operations	17
3.4. Using HTTP Client Libraries	17
3.5. Handling Redirects	18
3.6. Using Range Headers	18
3.7. Multi-Threading	19
3.8. Using Persistent Connections	19
Chapter 4. Introduction to the Simple Content Storage Protocol (SCSP)	20
4.1. Mapping SCSP Operations to HTTP Methods	20
4.2. HTTP Overview	21
4.3. Requests and Responses	21
4.3.1. HTTP Response Codes	21
4.3.2. Redirect Responses	22
4.4. Formatting SCSP Commands for Named and Unnamed Objects	22
4.5. Undefined Responses from DX Storage	23
4.6. Normal Response Headers	24
Chapter 5. SCSP READ	27
5.1. Introduction to READ	27
5.1.1. Reading With Content Validation	27
5.1.2. Requestion Node Status and Cluster Capacity	27
5.2. Unnamed Object READ Details	28
5.3. Normal Responses to READ	28
5.3.1. Normal READ Responses for Named Objects	28
5.3.1.1. Normal READ Response for a Domain	28
5.3.1.2. Normal READ Response for a Bucket	29
5.3.1.3. Normal READ Response for a Named Object	29
5.3.2. Normal READ Response for Unnamed Objects	29
5.3.3. Other Normal READ Responses	30
5.4. Error Responses to READ	30
Chapter 6. SCSP WRITE	32
6.1. Introduction to WRITE	32
6.1.1. About the Expect: 100-continue Header and WRITE	33
6.1.2. About Replicate On Write	33
6.2. Named Object WRITE Details	33
6.3. Unnamed Object WRITE Details	33
6.4. Normal Responses to WRITE	33
6.5. Error Responses to WRITE	34
Chapter 7. SCSP DELETE	36
7.1. Introduction to DELETE	36
7.2. Unnamed Object DELETE Details	37
7.3. Named Object DELETE Details	37
7.4. Normal Responses to DELETE	37
7.5. Error Responses to DELETE	38
Chapter 8. SCSP UPDATE	39
8.1. Introduction to UPDATE	39
8.2. Unnamed Object UPDATE Details	39
8.3. Normal Responses to UPDATE	40
Chapter 9. SCSP COPY	41
9.1. Introduction to COPY	41
9.2. Unnamed Object COPY Details	41
9.3. Normal Responses to COPY	41
Chapter 10. SCSP APPEND	42
10.1. Introduction to APPEND	42
10.2. Unnamed Object APPEND Details	43
10.3. Normal Responses to APPEND	43
Chapter 11. SCSP INFO	44
11.1. Introduction to INFO	44
11.1.1. Getting Replica Counts	44
11.1.2. Getting Node Status and Cluster Capacity	44
11.2. Unnamed Object INFO Details	45
11.3. Normal Responses to INFO	45
11.3.1. Normal INFO Responses for Named and Unnamed Objects	45
11.3.2. Normal INFO Responses for Named Objects	46
11.3.3. Normal INFO Responses for Unnamed Objects	47
11.4. Error Responses to INFO	47
Chapter 12. Introduction to Object Security	48
12.1. About Security Roles	48
12.2. Security Realm Overview	49
12.2.1. Common Security Terminology	49
12.2.2. About Security Realms	49
12.2.3. About Realm Caching and Security	49
12.3. About Authorization Header Syntax	50
12.3.1. About Realm Names	51
12.3.1.1. About Realms and Buckets	51
12.3.1.2. About owner@ and @owner Syntax	51
12.3.1.3. About user@realm Syntax	51
12.4. Authorization Specification Examples	51
12.5. About Authorization Header Evaluation	52
12.6. Creating Realms	53
12.7. Updating the Realm on a Bucket	54
12.8. Administrative Override and Security	54
Chapter 13. Managing Security for Application Developers	55
13.1. What Application Developers Need to Know	55
13.2. About Bucket Authorization	55
13.3. Example: Creating Bucket Owners	56
13.4. Examples of Creating Buckets and Named Objects	56
Chapter 14. Managing Security for Domain Managers	59
14.1. What Domain Managers Need to Know	59
14.2. About Domain Manager Tasks and Responsibilities	59
14.3. Examples of Updating Domain and Administrator User Lists	59
14.3.1. Updating the Domain Realm	60
14.3.2. Updating the Domain Manager Realm	61
14.3.3. Updating a Realm Using PUT	62
Chapter 15. Using the Content-MD5 Metadata Header	64
Chapter 16. Using Lifepoint Metadata Headers	65
16.1. About Storage Policies	65
16.2. A Simple Lifecycle Example	65
16.3. Lifepoint/Lifecycle Specification	66
16.4. Constraint Types	66
16.4.1. Replication	67
16.4.2. Deletion	67
Chapter 17. Using the Allow Metadata Header	69
17.1. Overview of the Allow Header	69
17.2. Administrative Override	69
Chapter 18. Using Caching Metadata Headers	71
18.1. About Caching Headers	71
18.2. Using HTTP/1.0 Caching Headers	71
18.2.1. Last-Modified	71
18.2.2. If-Modified-Since	71
18.2.3. If-Unmodified-Since	71
18.2.4. Expires	72
18.3. Using HTTP/1.1 Caching Headers	72
18.3.1. ETag	72
18.3.2. If-Match	72
18.3.3. If-None-Match	73
18.3.4. If-Range	73
Chapter 19. Using Custom Metadata Headers	75
Chapter 20. Basic Content Integrity Assurance	76
20.1. Integrity Seals	76
20.2. Validating Reads	76
20.3. Application Initiated Hash Upgrading	77
Appendix A. Content Header Metadata	78
Appendix B. Sample Code and Client Library Behaviors with 100-Continue	80

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Version 5.0

December 2010

Currently, DX Storage understands only one application-level protocol, the Simple Content Storage

Protocol (SCSP), which is a subset of the Hypertext Transfer Protocol,

HTTP/1.1

used by web

servers and browsers. While it is possible that additional access protocols will be added to DX

Storage in the future, HTTP is the only protocol supported for the URI at this time.

A DX Storage cluster is addressed using either the DNS name or the IP address of one of the

nodes in the cluster. It doesn't matter which node is addressed initially, as long as it is accessible

to the application on the network. Of course, if the addressed node has failed, or is offline for some

reason, your URI might need to change. Note that it is

not

necessary that the node named in the

URI be the same one that actually stored the object in the first place because any node can be

asked to retrieve any object stored on any other node in the cluster.

For unnamed objects, the UUID of an object to be retrieved from a DX Storage cluster is specified

in the last component of the URI as a string of 32 case-insensitive hexadecimal digits. The length

of the UUID string must always be exactly 32 characters (any leading zeros must be included).

When storing an object for the first time, obviously there is no UUID assigned yet. Therefore, a

WRITE request in SCSP includes just the first two components of the URI. After the data has been

transferred and stored, DX Storage generates and returns a new UUID to the application.

1.8. About Objects and Security

Starting with DX Storage version 5.0, you can optionally use security with named and unnamed

objects. You can, for example, enable only users in a particular security realm to make changes to

an object and prevent any other users from changing the object. You can apply security to buckets

and to named or unnamed objects.

The following figure shows a simple example of using security.

In the example, the user Joe has access to the

docs

bucket where he can create named objects

and user Jim has access to the

videos

bucket. Neither Joe nor Jim can write named objects to any

other domain in the cluster (

cloud.com

1.8.1. The Basics of DX Storage Security

DX Storage's security model uses the standard two-part approach of:

•

Authentication

: DX Storage uses standard Digest Access Authentication as discussed in

RFC

2617

to create one-way cryptographic hash algorithms to obscure identity information over

the Internet while allowing a client (for example, a web browser) and the DX Storage server to

exchange enough information to consummate authentication.

DX Storage validates user names and passwords from a

security realm

, which is discussed in the

next section.

•

Authorization

: Provided a user authenticates successfully, the user's privileges are derived

from the

authorization specification

associated with the object the user attempts to access. The

authorization specification is discussed in the next section.