Space Based Programming

Space based programming [email_address] @gojkoadzic http://gojko.net

Why should you care?
It helps us build applications that:
can scale out to lots of machines easily
can grow and shrink dynamically
have massive throughput
handle massive amounts of data

So what are spaces?
Data spaces are “network attached memory”, allowing us to read, put or take objects
Space takes care of redundancy, failover, transactions …
Alternatively, send tasks to the object and let it execute it.

The idea has been around for a while, but somehow has not caught on… however it’s coming back with a bang!

Another language named after a Lovelace

David Gelertner invents Linda in the 80’s
Distributed processing based on tuples
Orthogonal process coordination
Data coupling rather than process coupling

Sun Jini in the 90’s
Evolvable architectures, autodiscovery and lots of other flux capacitors nobody needed or knew how to use at the time…

Grid computing in 00's

Great for computations, but what about transaction processing?

Space-based systems will be key for cloud scalability

Products
http://coherence.oracle.com
http://www.gigaspaces.com
http://virtuoso.openlinksw.com/
http://www.almaden.ibm.com/cs/TSpaces/
http://www.jboss.org/infinispan

Command Pattern (GOF)‏
“ is a design pattern in which an object is used to represent and encapsulate all the information needed to call a method at a later time”... (wikipedia)‏

You need a recipient, probably an entity by ID

You need a “recipient”, probably an entity by ID A “command” with all the information required to run it

You need a “recipient”, probably an entity by ID A “command” with all the information required to run it And an “invoker” to do the job

And the command gets executed...

So what does it have to do with spaces?
“ ...makes it easier to construct general components that need to delegate, sequence or execute method calls” (also wikipedia)

You can use many invokers

And do loads of work in parallel

And you can do something more productive with your time...

So what does that have to do with spaces?
Space is where recipients reside and where you send commands
Lots of different processors run in the space, but from the outside appear as a single “mind”
This scales really well and it is virtually indestructible....

Space: all your objects

Processing units (=partitions)‏

GigaSpace data objects [SpaceClass] public class Message { [SpaceID(AutoGenerate=true)] public String MessageId {get; set;} [SpaceRouting] public String MessageType{ get; set;} ... }

Space Data Properties
[SpaceID] is unique for the class in Space
[SpaceRouting] determines the partition (defaults to space ID)
Indexes speed up queries
[SpaceProperty(Index=SpaceIndexType.Basic)]
[SpaceVersion] for optimistic locking
[SpaceExclude] are not serialized

Recipient (Command context)‏
Space object
Space ID is the entity ID
Routing ID is the same field

Commands
Space object
Space ID is a GUID (can be auto-generated)‏
Target recipient ID is the Routing ID

Processing Units
Worker thread pool
Template matches the command
Class matching
Property matching (if not null)‏
Works inside a PU container

Example processor [PollingEventDriven(MinConcurrentConsumers = 1, MaxConcurrentConsumers = 4)] internal class MessageProcessor { [EventTemplate] public Message TemplateForThisProcessor { get{ ... } } [DataEventHandler] public Message ProcessMessage(Message message) {.... } }

Processes
Contain one or more processing unit containers
Own a space partition
Run on the network, balanced, clustered, backed up

Coherence - distributed HashMaps
Works on POCO objects, but you can implement PortableObject for .NET/Java interop
void IPortableObject.ReadExternal(IPofReader reader)
{
firstName = reader.ReadString(0);
addrHome = (Address)reader.ReadObject(1);
....
void IPortableObject.WriteExternal(IPofWriter writer)
{
writer.WriteString(0, firstName);
writer.WriteObject(1, addrHome);

Works as a hashmap
INamedCache cache = CacheFactory.GetCache(“my map”);
cache.Add(key, value)
cache.Remove(key, value)
Also supports queries, notifications etc

Entry Processors – push code to objects
cache.Insert("BGD", new Temperature(25, 'c', 12));
IValueUpdater updater = new ReflectionUpdater("setDegree");
IEntryProcessor processor = new UpdaterProcessor(updater, 26);
object result = cache.Invoke("BGD", processor);

Key ideas to do it efficiently
Forget about n-tier systems
Group data together with all processes
Ensure that invokers have all the information needed to run (so no unnecessary serialization)‏
Ensure that the recipients are the correct aggregates for execution (so low contention during execution)‏
Use asynchronous persistence

That's it for now...
http://gojko.net
http://ukdotnet.ning.com
October 1st, Mike Hadlow on MassTransit

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Space Based Programming

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