Space based programming

gojko@gojko.com@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