Explore how we can begin to move functionality from a typical RDBMS application to one that uses tools and frameworks like MongoDB, Solr and Redis. At the end, the architecture we've evolved looks similar to.........

1. Being RDBMS Free
DAVID HOERSTER
2014

2. About Me
C# MVP (Since April 2011)
Sr. Director of Web Solutions at RGP
Conference Director for Pittsburgh TechFest
Co-Founder of BrainCredits (braincredits.com)
Past President of Pittsburgh .NET Users Group and organizer of recent Pittsburgh Code
Camps and other Tech Events
Twitter - @DavidHoerster
Blog – http://geekswithblogs.net/DavidHoerster
Email – david@agileways.com

3. Traditional Architecture
Data persistence is central to application
Generally monolithic
Jack of all trades; master of none

4. Traditional Architecture
Client
Web
Server
App
Server
Data
Repository
Data Tables
Session
Cache (?)
FT Search

5. What if…
We could break some pieces out
◦ Flatten structures for querying
◦ Highly efficient search services
◦ Pub/sub hubs
◦ Remote caching with excellent performance
◦ Session management outside a DB for load balanced environments
How would app then be architected?

6. Search
How do you search?
◦ LIKE ‘%blah%’ ?
◦ Dynamic SQL
◦ Full-Text
LIKE and Dynamic SQL can be quick to create
◦ Tough to maintain
Full-Text gives power
◦ Limited in search options

7. Search
Number of search services out there like
◦ Lucene
◦ Solr
Lucene is a search engine
◦ Embed in apps
◦ .NET port (Lucene.NET)
Solr is search service
◦ Built on Lucene
◦ Connect apps to it

8. Searching with Solr
Disconnected from your application
Search content via HTTP REST calls
Can use SolrNet as a client
◦ https://github.com/mausch/SolrNet
Document-based

9. Searching with Solr
private readonly ISolrOperations<T> _solr;
public SolrSearchProvider(ISolrOperations<T> solr) { _solr = solr; }
public IEnumerable<T> Query(String searchString) {
var options = new QueryOptions() {
Fields = new List<String> {"title", "body", "lastModified" }.ToArray(),
Highlight = new HighlightingParameters() {
BeforeTerm = "<strong><em>",
AfterTerm = "</em></strong>",
Fields = new List<String> { "title", "body" }.ToArray(),
Fragsize = 100
}
};
var results = _solr.Query(new SolrQuery(searchString), options);
return results;
}

10. Evolving Architecture
Client
Web
Server
App
Server
Data
Repository
Data Tables
Session
Cache (?)
Search
Service
Query
Write

11. Data Storage
Typically, RDBMS is the de facto standard
◦ SQL Server
◦ MySQL
◦ PostgreSQL
◦ Oracle (Yikes!!)
But do you really need it?

12. Data Storage
Get all the orders for user ‘David’ in last 30 days
SELECT c.FirstName, c.MiddleName, c.LastName, soh.SalesOrderID, soh.OrderDate,
sod.UnitPrice, sod.OrderQty, sod.LineTotal,
p.Name as 'ProductName', p.Color, p.ProductNumber,
pm.Name as 'ProductModel',
pc.Name as 'ProductCategory',
pcParent.Name as 'ProductParentCategory'
FROM SalesLT.Customer c INNER JOIN SalesLT.SalesOrderHeader soh
ON c.CustomerID = soh.CustomerID
INNER JOIN SalesLT.SalesOrderDetail sod ON soh.SalesOrderID = sod.SalesOrderID
INNER JOIN SalesLT.Product p ON sod.ProductID = p.ProductID
INNER JOIN SalesLT.ProductModel pm ON p.ProductModelID = pm.ProductModelID
INNER JOIN SalesLT.ProductCategory pc ON p.ProductCategoryID = pc.ProductCategoryID
INNER JOIN SalesLT.ProductCategory pcParent ON pc.ParentProductCategoryID = pcParent.ProductCategoryID
WHERE c.FirstName = 'David'
AND soh.OrderDate > (GETDATE()-30)

13. Data Storage
Wouldn’t it be great if it were something like this?
SELECT FirstName, MiddleName, LastName, SalesOrderID, OrderDate,
UnitPrice, OrderQty, LineTotal, ProductName, Color, ProductNumber,
ProductModel, ProductCategory, ProductParentCategory
FROM CustomerSales
WHERE FirstName = 'David'
AND OrderDate > (GETDATE()-30)

14. Data Storage
Maybe a document database can be of use
Number out there
◦ MongoDB
◦ RavenDB
◦ Couchbase
Flattened structures without relational ties to other collections
Essentially object databases

15. Looking at MongoDB
Server can have databases
Databases contain collections (like a table)
Collections contain documents (like rows)
Documents can be structured, have constraints, have primary key

16. Working with Mongo’s C# Client
public class MongoContext<T> : IContext<T> where T : class, new() {
private IDictionary<String, String> _config;
private readonly MongoCollection<T> _coll;
public MongoContext(IDictionary<String, String> config) {
_config = config;
var client = new MongoClient(config["mongo.serverUrl"]);
var server = client.GetServer();
var database = server.GetDatabase(config["mongo.database"]);
_coll = database.GetCollection<T>(config["mongo.collection"]);
}
public IQueryable<T> Items {
get { return _coll.FindAll().AsQueryable(); }
}
}

17. Working with Mongo’s C# Client
Encapsulate my queries and commands
public class FindPageById : ICriteria<Page> {
private readonly String _id;
public FindPageById(String pageId)
{
_id = pageId;
}
public IEnumerable<Page> Execute(IContext<Page> ctx)
{
return ctx.Items.Where(p => p.Id == _id).AsEnumerable();
}
}

18. Working with Mongo’s C# Client
Invoke my query/command
public class TemplateController : IportalBaseController {
private readonly IContext<Page> _pages;
public TemplateController(IContext<Page> ctx) : base() {
_pages = ctx;
}
[HttpGet]
public async Task<IportalPageMetadata> Section(String cat, String page) {
var id = String.Format("{0}/{1}", cat, page);
var thePage = new FindPageById(id)
.Execute(_pages)
.FirstOrDefault();
...
}
}

19. Working with Mongo’s C# Client
Writing to Mongo is just as simple...
[HttpPost]
public async Task<Boolean> Post(Page page)
{
var userId = await GetUserId();
new CreatePage(page, userId)
.Execute(_pages);
_searchPage.Insert(page);
return true;
}

20. Evolving Architecture
Client
Web
Server
App
Server
Data
Repository
Some data (?)
Session
Cache (?)
Search
Service
Query
Write
Document
Repository
Write
Query

21. Session and Cache Data
Generally short-lived for users
Fairly static for cached data
Key/value stores can serve us well here
◦ Redis
Redis has two good .NET client libraries
◦ StackExchange.Redis
◦ ServiceStack.Redis

22. Using Redis
public class RedisSessionManager : ISessionManager {
private static ConnectionMultiplexer _redis = null;
private readonly IDictionary<String, String> _config;
public RedisSessionManager(IDictionary<String, String> config) {
if (_redis == null) {
_redis = ConnectionMultiplexer.Connect(config["session.serverUrl"].ToString());
}
_config = config;
}
public async Task<Boolean> CreateSession(String portalId, String userId, String fullName) {
var time = DateTime.UtcNow.ToString();
var timeout = _config.ContainsKey("session.timeout");
var vals = new HashEntry[] {
new HashEntry("userid", userId), new HashEntry("login", time),
new HashEntry("lastAction", time), new HashEntry("fullName", fullName)
};
await RedisDatabase.HashSetAsync(portalId, vals);
return await RedisDatabase.KeyExpireAsync(portalId, TimeSpan.FromMinutes(timeout));
}
}

23. Using Redis
public async Task<Boolean> ExtendSession(String portalId) {
var timeout = _config.ContainsKey("session.timeout");
await RedisDatabase.HashSetAsync(portalId, "lastAction", DateTime.UtcNow.ToString());
return await RedisDatabase.KeyExpireAsync(portalId, TimeSpan.FromMinutes(timeout));
}
public async Task<Boolean> ExpireSession(String portalId) {
return await RedisDatabase.KeyDeleteAsync(portalId);
}

24. Using Redis
At login:
await Session.CreateSession(portalid, UserHandle, fullName);
Upon log out:
await Session.ExpireSession(portalCookie.Value);

25. Evolving Architecture
Client
Web
Server
App
Server
Data
Repository
Some data (?)
Search
Service
Query
Write
Document
Repository
Write
Query
Session/
Cache
Service

26. Why Data Store
We’re left with a database with not much use
◦ Transactional data in document store
◦ Search documents in Solr
◦ Session, caching, etc. in key/value or caching service like Redis
What it probably ends up acting as is…

27. Evolving Architecture
Client
Web
Server
App
Server
Event Store
2-3 flat tables
Event data
Search
Service
Query
Write
Document
Repository
Write
Query
Session/
Cache
Service
Queue?

28. (D)Evolved Architecture
Client
Web
Server
App
Server
Event
Store
Search
Service
Query
Write
Doc
Repo
Write
Query
Session/
Cache
Service
Queue?

29. (D)Evolved Architecture
Pick and choose what components work best
Don’t use them just to use them
Proof-of-Concept / Prototype

30. Why look to be RDBMS free
Searching
◦ More than just full-text needs
Data
◦ Choose a system that you can model the business
◦ Not the other way around
Caching / Session Values / PubSub
◦ Offload necessary?
◦ Ensure performance
Maintenance and support big factors to consider