VOS.DataSpaceFAQ

Data Space FAQ

What is a Data Space?

A Data Space is an atomic point of presence in cyberspace (Internet, Web, Blogosphere, Wikisphere etc.) for interacting with Data, Information, Knowledge, and Services. Its content may be imported from, or simply point to data in, other Data Spaces. In all cases the content is either transient (generated "on the fly") or persistent (supported by cache synchronization schemes).

What would you typically find in a Data Space?

You would find the following:

• Raw Data -- SQL, HTML, XML (raw), XHTML, RDF etc.
• Information (Data In Context) -- XHTML (various microformats), Blog Posts (in RSS, Atom, RSS-RDF formats), Subscription Lists (OPML, OCS, etc), Social Networks (FOAF), and many other forms of applied XML.
• Knowledge -- Domain specific Concepts and Terms available in transient or persistent forms expressed in RDF with Domain, Schema, and Instance Data serialized using formats such as RDF-XML, N3/Turtle, etc., e.g., FOAF, SIOC, and Atom OWL, amongst others
• Web Services -- REST or SOAP based invocation of application logic for context sensitive and controlled interaction with Data Space content

How do Data Spaces and Databases differ?

Data Spaces are fundamentally problem-domain-specific database applications. They offer functionality that you would instinctively expect of a database (e.g. ACID data management) with the additional benefit of being data model and query language agnostic. Data Spaces are for the most part DBMS Engine and Data Access Middleware hybrids in the sense that ownership and control of data is inherently loosely-coupled.

How do Data Spaces and Content Management Systems differ?

Data Spaces are inherently more flexible, they support multiple data models and data representation formats. Content management systems do not possess the same degree of data model and data representation dexterity.

How do Data Spaces and Knowledgebases differ?

A Data Space cannot dictate the perception of its content. For instance, what I may consider as knowledge relative to my Data Space may not be the case to a remote client that interacts with it from a distance, Thus, defining my Data Space as Knowledgebase, purely, introduces constraints that reduce its broader effectiveness to third party clients (applications, services, users etc..). A Knowledgebase is based on a Graph Data Model resulting in significant impedance for clients that are built around alternative models. To reiterate, Data Spaces support multiple data models.

What Architectural Components make up a Data Space?

• ORDBMS Engine - for Data Modeling agility (via complex purpose specific data types and data access methods), Data Atomicity, Data Concurrency, Transaction Isolation, and Durability (aka ACID).

• Virtual Database Engine - for creating unified views of heterogeneous RDF, SQL, XML, Free Text, and other data. This is all about Virtualization at the Data Access Level.

• Web Services Platform - enabling controlled access and manipulation (via application, service, or protocol logic) of Virtualized or Disparate Data. This layer handles the decoupling of functionality from monolithic wholes for function specific invocation via Web Services using either the SOAP or REST approach.

Where do Data Spaces fit into the Web's rapid evolution?

They are an essential part of the burgeoning Data Web / Semantic Web. In short, they will take us from data "Mash-ups" (combining web accessible data that exists without integration and repurposing in mind) to "Mesh-ups" (combining web accessible data that exists with integration and repurposing in mind).

Where can I see a Data Space along the lines described, in action?

My Blog Data Space:

1. Front Door (Web 1.0) via Home Page
2. Lounge (Web 2.0) via GData, OpenSearch, XQuery, and XPath
3. Floor Plan via FOAF and/or SIOC Ontology based RDF Data Sets (Graphs)
4. Rest of the House (Web 3.0 / Semantic Web / Data Web) via SPARQL Query Endpoint for My Data Space on MyOpenLink.net.

Some of RDF Data Sets exposed via My Data Spaces:

• My Weblog Data Space (exposed via FOAF? Ontology)
• My General Data Space (exposed via the FOAF? Ontology)
• My Weblog Data Space (exposed via SIOC? Ontology)
• My General Data Space (exposed via the SIOC? Ontology)

What about other Data Spaces?

There are several, classifiable by query method available:

Type 1 -- Generic Free Text Search over HTTP

Google, MSN, Yahoo!, Amazon, eBay, and most Web 2.0 plays.

Type 2 -- Generic Free Text Search, OpenSearch?, GData, and XQuery/XPath over HTTP

A few blogs and Wikis (Jon Udell, Kingsley Idehen, and a few others)

Type 3 -- RDF Data Sets and SPARQL Queryable

• SIOC enabled online points of presence
• PingTheSemantic Web Data Space

Type 4 -- Generic Free Text Search, OpenSearch?, GData, XQuery/XPath, and SPARQL

A few Semantic Web early adopter sites (but none include Free Text, XQuery/XPath, and SPARQL hitting endpoints within the same internet domain).

What About Data Space aware tools?

• OpenLink Ajax Toolkit - provides JavaScript? Control level binding to Query Services such as XMLA for SQL, GData for Free Text, OpenSearch? for Free Text, SPARQL for RDF, in addition to service specific Web Services (Web 2.0 hosted solutions that expose service specific APIs)
• Semantic Radar - Firefox Plugin
• PingTheSemantic Web Data Space
• PiggyBank

How can I manage my tags sets?

• Tag Administration: The ODS DataSpace Settings page contains a link to "Content Tagging Settings."
• Rule Set Edit: This page allows editing the rules which compose a rule set.
• Rules Sets: This is a scrollable list of tagging rules. Each is shown with its rule name. Each entry has a check box before it for selection for Remove, Up and Down links. Hitting the rule name link will show the text of the rule in the Add rule form above. Clicking Add will replace the original rule.

More information you can find here.

How do I Generate OAuth Keys for ODS Controllers (Web Services)?

OAuth is an open protocol to allow secure API authentication in a simple and standard method from desktop and web applications.

OAuth allows the user to grant access to their private resources on one site (the Service Provider), to another site (called Consumer). OAuth is about giving access to your information without sharing all of your identity.

In ODS you can setup Application OAuth keys from Settings->OAuth keys. There you can select Application name from the drop-down list and click the "Generate Keys" button. As result for the selected application will be shown the generated Token and Secrete values.

More information you can find here.

How to Give My Data Space Content Tags Meaning via MOAT Ontology?

MOAT (Meaning Of A Tag) provides a Semantic Web framework to publish semantically-annotated content from free-tagging.

MOAT Server is a application that serves tag meanings (in HTML, JSON or RDF/XML, using content negotiation for any Tag you request.

In ODS logged in as administrator, at Site Settings->Web Application Configuration you can define MOAT server with server URL and server key.

More information you can find here.

How can I set Content Tagging using MOAT?

In ODS logged in as regular user, at Settings->Content Tagging Settings you can add new rules for which defined tagging rules is used the MAOT feature for importing meanings.

More information you can find here.

How can I get a Personal URI?

Your own ODS Data Space Personal URI is valid for linking to/from any Linked Data service.

More information you can find here.

How do I set <a> links?

The settings for <a>++ links can be changed in ODS Framework UI->user name->Edit My Profile->Personal page, drop-down list "Show <a>++ links". The options scope is:

• disabled - this is the default;
• click - the anchor is opened when user clicks the RDF icon shown at the right of the link;
• hover - the anchor is opened when the cursor hovers over the RDF icon shown at the right of the link.

More information you can find here.

How can I use the WebDAV browse feature for ODS users browsing file content?

Virtuoso offers a short way to view ODS user's WebDAV file content. All you need to do is for existing ODS user to access the following url:

http://host:port/~<odsuser>/<name of the file>.

How can I use the WebDAV browse feature for ODS users browsing folder content?

You can browse the ODS user's WebDAV Public folder by accessing the following url:

http://host:port/~<ods-user>/Public. 

For ex.: http://demo.openlinksw.com/Public

How do I use Yadis?

Yadis is an authentication service discovery protocol allowing Compliant Clients (identity consumers or member-sites) to deductively determine authentication protocol options available from a service provider.

The ODS Yadis URL is:

http://host:port/dataspace/[your-ods-username]

More information you can find here.

How do I use OpenID?

OpenID is an open, decentralized system for user-centric digital identity. It works on the concept that anyone can identify themselves on the Internet the same way websites do - with a URI (sometimes called a URL or web address, somewhat inaccurately).

ODS supports the OpenID Authentication 1.1 and registration extension 1.0. ODS includes OpenID Server and client side implemented in the weblogs comments using AJAX. When posting a comment, a Web Site url is needed to be entered in order to be verified the authentication against a Server that supports OpenID. The implementation code is located in the openid.js and openid.sql files from the ODS package.

To see how it works, perform the steps from Weblog example.

What can I share in ODS?

In ODS you can share your contacts, bookmarks, files and folders, calendar event and tasks. For more information see here.

What can I publish in ODS?

In ODS you can publish your contacts, bookmarks, files and folders, calendar event and tasks. For more information see here.

Can my ODS account use the sparql-auth endpoint for executing queries?

Yes, ODS users can perform SPARUL over the SPARQL protocol after authentication at the http://host:port/sparql-auth endpoint. For more information you can see here.

Are Ubiquity Commands supported?

Yes. ODS and its applications support Ubiquity Commands. The full list of commands you can find here?.

Can I use OAuth for ODS Application Authentication?

Yes. Examples you can find here.

What Ubiquity Commands can I use to make publications and subscriptions within My ODS DataSpace?

A full list and examples of ubiquity publication and subscription commands you can find here.

Can I use the Virtuoso OAuth Test Tool for manipulating my ODS DataSpace data?

Yes. A tutorial and further information you can find here.

How to Register ODS User using OpenID2? Url?

Virtuoso supports OpenID2?. You can register ODS user using OpenID2? Url. A sample tutorial can be found here.

What is the proper way to query private data in a user's dataspace via the SPARQL endpoint?

When querying a data space via SPARQL you need to be aware of the target data sources which take the form of information resource (web doc) URLs or internal RDF Store Graph IRIs.

In ODS, when you create an account, you end up with a personal identifier (also known as a Web ID or Personal URI). The personal identifier is associated with an information resource that takes the form of a FOAF based profile page. Thus, if you want to query you own data space you simply need to aim you SPARQL queries at your FOAF profile page URL which takes the form: http:///dataspace/person/ .

On the other hand you can also SPARQL across the entire collection of public data hosted by an ODS instance if you scope your queries to the ODS data space Graph IRI: http:///datataspace .

You achieve the SPARQL scope via:

1. FROM clause of your SPARQL query (of the Data Source URL input filed presented in the /sparql endpoint UI)
2. Virtuoso SPARQL pragmas via: define graph-iri <http://cname/dataspace>

With the recent support of FOAF+SSL, the ACL capabilities of the ODS instance and its SPARQL endpoint goes beyond explicit ODS membership. Thus, if someone has a URI bound to a self-certified certificate where the public key component is written to their FOAF profile page, such individuals will also have SPARQL access to shared resources via an HTTPS based SPARQL endpoint.

See more information for ODS SPARQL OAuth.

Is OpenSocial API supported?

Yes. The ODS package contains OpenSocial data APIs about people and activities. More information and sample examples you can find here.

Is FOAF+SSL supported in OpenLink Data Spaces?

Yes. Full description and sample examples you can find here.

Can I Set FOAF+SSL ACLs?

Yes. This feature now is offered from the Virtuoso Authentication Server UI. More information and sample scenario you can find here.

How Do I Use the Virtuoso OAuth Test tool to manage my Data Space data?

Detailed Information and sample examples you can find here.

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