This document provides an overview of the Open Data Protocol (OData). It introduces OData, including its background and purpose in addressing problems with data APIs. The key aspects of OData are summarized, including its use of URIs and conventions for queries. Methods for producing and consuming OData feeds using ASP.NET Web API and LINQ are demonstrated. Best practices for OData producers and consumers are outlined. The document encourages the use of OData to empower users and unlock new revenue from organizational data.

1. GAININGTHE KNOWLEDGE OF
THE OPEN DATA PROTOCOL
(ODATA)
ChrisWoodruff

2. WHO I AM?
ChrisWoodruff
MVP,Visual C#
Director at Perficient
Co-host of Deep Fried Bytes Podcast
@cwoodruff / cwoodruff@live.com
Skype: cwoodruff

3. YOUWILL LEARN:
 Understand the background of OData
 Have an understanding of the OData protocol
 How to produce an OData feed using WCF Data
Services
 How to produce an OData feed using ASP.NET
Web API
 How to consume an OData feed using LINQ

4. BACKGROUND
Knowledge of OData

5. QUOTE
Today, the tools for capturing
data both at the mega-scale
and at the milli-scale are just
dreadful. After you have
captured the data, you need
to curate it before you can
start doing any kind of data
analysis, and we lack good
tools for both data curation
and data analysis.
Jim Gray

6. Problem: Data APIs frequently
create more problems than
solutions
THISTALK IS ABOUT ONE SOLUTION.

7. SURVEY
…knows what the web is
…are comfortable w/ HTTP and
XML? JSON?
…have a basic understanding of
the term REST
…have created a Data API

8. Is there really a problem?
What is it?
QUIZTIME

9. FACEBOOK: WHAT FIELDSWILL I
GETWHEN I READ A POST?

10. FACEBOOK: HOW DOYOU LIKE A
POST?

11. How do developers
know what to do?
SO GIVENTHAT NOBODY KNEWTHE ANSWERSTOTHESE
QUESTIONS,

12. I GUESSTHEY USE DOCS

13. So is there really a problem?
Yes
DEVELOPERS DON’T HAVETIMETO ACTUALLY READTHE DOCS

14. Can OData Magically cure the
problem? No, but it can help.
LET’S SEE HOW

15. THE PROTOCOL
Knowledge of OData

16. THE BASICS OF ODATA
Feeds, which are Collections of typed Entities
OData services can expose Actions and Functions (v4),
Services (v3)
OData services expose all these constructs via URIs
OData service may also expose a Service Metadata Document

17. FULL SQL LIKE QUERY
“LANGUAGE”
HTTP Command
(Verb)
SQL
Command
GET SELECT
PUT UPDATE
POST INSERT
DELETE DELETE

18. THE $METADATA ENDPOINT

19. CONVENTIONS
http://services.odata.org/OData/OData.svc
_______________________________________/
|
service root URI
http://services.odata.org/OData/OData.svc/Category(1)/Products?$top=2&$orderby=name
_______________________________________/ __________________/ _________________/
| | |
service root URI resource path query options

20. URL CONVENTIONS
$filter
/Suppliers?$filter=Address/City eq 'Redmond‘
$orderby
/Products?$orderby=ReleaseDate asc, Rating desc
$top and $skip
/Products?$top=5&$skip=2
$select and $expand
/Products?$select=*,Category/Name&$expand=Category

21. COMBINING UEL CONVENTIONS
http://.../Players/
?$skip=10
&$top=2
&filter=substringof(‘Wood',nameLast)
&$orderby=nameLast%20desc
&$select=nickname,yearBorn,nameFirst
&$format=json

22. PAYLOAD CONVENTIONS
 Success and errorCodes
 200 OK, 201 Created, 415 Unsupported MediaType, etc
 Overall Format
 JSON
 AtomPub
 JSONVerbose
 Nuances
 PATCH, Null payloads, etc

23. JSON FORMAT
 Friendly to Javascript
 90% more compact than AtomPub
 Reads like a custom API
 Very little OData “gunk”

24. ATOM FORMAT
 Atom parsers exist in many frameworks
 Element fields can be mapped to their Atom
counterparts
 A good example of OData interoperability

25. WHAT ELSE CANYOU DO WITH
ODATA?
 Actions and Functions allow hypermedia-based
method calls (non-CRUD operations)
 Defined conventions for PATCH and deep insert
 Vocabularies

26. ODATA ISN’T ALWAYSTHE BEST
FIT
 OData may not be a good fit for highly opinionated APIs
laden with developer intent
 OData may not be a good fit for bulk data transfer
 OData may not be a good fit for the APIs that dramatically
different in shape than the backend

27. ODATA DOES NOT SUPPORT ALL
QUERIES
 OData doesn’t currently support aggregation
 You can’t ask for customers that have at least 2 orders
 OData doesn’t currently support filters expansions
 You can’t ask for a customer and only their orders placed in 2013
 OData doesn't support “graph” queries
 You can ask friend-of-a-friend type queries, but there are limitations

28. ODATA IS A STANDARD!!
 OASIS, ISO
 Ratified in March!

29. WHO USES ODATA?

30. WHAT DOES ODATA GIVE ME AND
MY ORGANIZATION?
Empower Internal
Power Users
Empower Existing and
Future Customers
Monetize Data for
untapped Revenue

31. CREATING FEEDW/
ASP.NETWEB API
Knowledge of OData

32. ASP.NETWEB API
DEMO

33. ODATA BEST PRACTICES
(PRODUCER)
 Always design your OData feed will server-side paging if your
entity collections hold large amounts of data.
 Looks at server-side validation of queries and data updates
based on the user credentials sent through HTTP

34. CONSUMING ODATA
Knowledge of OData

35. WHAT IF DATA API’S WERE LIKE…
LINQ?
 What are the last 50 invoices we sent?
 context.Invoice.OrderByDescending(i=>i.PostedAt).Take(50);
 What are the invoices from the last 24 hours?
 context.Invoice.Where(i=>i.PostedAt >
DateTime.Now.AddDays(-1));
 How many $1M invoices have we sent?
 context.Invoice.Where(i=>i.TotalAmount >= 1000000);

36. ODATA BEST PRACTICES
(CONSUMER)
 Use Query Projection to only bring back the entity properties
you or your app needs.
 Think about client-side paging even if their exists server-side
paging.
 Design and implement a client-side data caching function in
your app (unless sensitive data).

37. WHY AREWE EXCITED!!

38. WRAP-UP
Knowledge of OData

39. The demo projects can be found at:
github.com/cwoodruff/

40. RESOURCES
REST
http://www.ics.uci.edu/~taylor/documents/2002-
REST-TOIT.pdf
OData
http://odata.org
http://odataprimer.com

41. CONTACT ME
Chris “Woody”Woodruff
cwoodruff@live.com
Twitter @cwoodruff
Skype cwoodruff
http://chriswoodruff.com
http://deepfriedbytes.com