1. HMA-S Final Presentation OGC 13-043 DSEO Protocol
D. Marchionni, Telespazio S.p.A.
June 11, 2014
HMA-S Final Presentation

2. Summary Status of the specification Protocol overview Interfaces
Requirements Classes
Conformance Classes & Tests
HMA-S Final Presentation

3. Status of DSEO Specification
OGC OGC Download Service for Earth Observation Products Best Practice (DSEO)
V1.0, Publication Date: 31/01/2014
Best Practice
What’s delivered:
The document: _OGC_Download_Service_for_Earth_Observation_Products.pdf
The schema files:
dseo.xsd
metalink.xsd
examples XML files
Schema file and examples not yet published on the OGC web site
HMA-S Final Presentation

4. Status of DSEO Specification
Document History:
Document submitted to OGC on 04/09/2013 (Esrin TC Meeting)
Motion for Electronic Vote approved on 23/09/2013 (BIDS DWG Meeting)
Electronic Vote
Started on: 05/11/2013
Completed on: 05/12/2013
Statistics:
YES: 24
NO: 0
Not Voted: 67
Approved Best Practice Document
HMA-S Final Presentation

5. Structure of the Document
The document has been prepared following the template from OGC (10-176r4_New_OGC_Document_Template_Draft)
Overview of the specification is provided at §6
The complete description of the protocol, including URLs, HTTP methods and XML messages is provided at §8
Requirement Classes provided in dedicated sections:
§9: Core Requirements Class
§10: On-Demand Download Requirements Class
Conformance Classes & tests provided in section §11:
§11.1: Core Conformance Class tests
§11.2: On-Demand Download Conformance Class tests
HMA-S Final Presentation

6. OGC DSEO Overview
The OGC Download Service For Earth Observation Products (DSEO) proposes as OGC Best Practice document the download protocol defined in ngEO ESA project.
The protocol supports the following scenarios:
The product is already available for download (on-line);
The product is under processing, but not ready yet (off-line / on-demand);
Additionally the following sub-cases are supported:
Product file available from multiple sources (parallel download);
The product is composed of multiple files, each possibly available from multiple sources (multiple download);
The product file is reachable via several HTTP redirections from the original URL.
Any combination of previous options.
HMA-S Final Presentation

7. OGC 13-043 DSEO Overview The DSEO protocol uses:
HTTP GET for all interactions;
HTTP redirections, in case of “virtual URL”;
Re-try mechanism according to specific HTTP returned codes, in case of on-demand products;
Metalink files for managing multi-file / multi-source download;
Key-Value Pairs (KVP) Encoding: the service operations receive parameters as list of key-value pairs in the request URL.
DSEO service operations:
GetCapabilities, in order to have compliance with OWS
GetProduct, the actual DSEO service operation
HMA-S Final Presentation

8. OGC 13-043 DSEO - GetCapabilities
GetCapabilities operation allows DSEO clients to retrieve the service metadata document from the server. This document specifies which operations can be invoked on the server, encodings, etc.
Request: it is a simple HTTP GET operation with KVP encoded parameters in the URL (service=DSEO, request=GetCapabilities, version=“1.0.0”, ...)
Example:
Response: the Capabilities XML document containing information about the service, supported operations, encodings, etc.
HMA-S Final Presentation

9. OGC DSEO - GetProduct
GetProduct operation allows DSEO clients to request a particular EO product identified by a URI.
Request: it is a simple HTTP GET operation with KVP encoded parameters:
Service: Service type identifier
Request: Operation name
Version: Standard version for operation
ProductURI: URI of the product to be downloaded.
Example:
HMA-S Final Presentation

10. OGC 13-043 DSEO - GetProduct GetProduct – Response: Response Name
HTTP Status
Response type
MIME Type
Description
Direct Download
200 – Ok
Binary
application/octet-stream
Product data
Metalink Download
XML
application/metalink+xml
Metalink file (Metalink.xsd)
Accepted Download
202 – Accepted
text/xml
dseo:ProductDownload Response (dseo.xsd)
Forwarded Download
303 – See Other
ASCII
text/html
See http specifications
Direct Download: single file on-line product;
Metalink Download: multi-file / multi-source on-line product (Multiple Download);
Accepted Download: off-line / on-demand download product;
Forwarded Download: external located product redirect information;
HMA-S Final Presentation

11. OGC DSEO - GetProduct
HMA-S Final Presentation

12. OGC 13-043 DSEO - Requirement Classes
As OGC Best Practice, the document shall include Requirement Classes.
Requirement Classes:
Core, regrouping all requirements for supporting direct download, multi file download (Metalink), multi source download (Metalink), redirection.
On-demand Download, inheriting from Core class and including the requirements for allowing download of product files not ready yet.
In this way we cover: servers supporting only already available products (Core class) and also servers supporting on-demand products (Core + On-demand Download).
HMA-S Final Presentation

13. OGC 13-043 DSEO - Conformance Classes
Conformance Classes: there is a 1:1 mapping between Requirement Classes and Conformance Classes, so we have:
Core (Conformance Class), regrouping all tests for verifying Core class requirements;
On-demand Download (Conformance Class), regrouping all tests for verifying On-demand Download class requirements.
HMA-S Final Presentation

14. OGC 13-043 DSEO - Conformance Tests
Conformance Tests: A conformance class is implemented via a set of conformance tests, each testing one or more requirements of the corresponding requirements class.
Core: contains the following conformance tests:
Capabilities
Capabilities request non-nominal conditions
Download of single file product
Download of multi-file product
Download of multi-source product
Redirected download of single file product
Product request non-nominal conditions
On-demand Download: contains the following conformance tests:
HMA-S Final Presentation

15. OGC 13-043 DSEO – Requirements & Conformance Statistics
Requirement Class
Core: 14 Requirements
OnDemand: 2 Requirements
Conformance Class
Core: 7 Conformance Tests
OnDemand: 4 Conformance Tests
HMA-S Final Presentation