Featherweight Clients (Athens, 2012)

Fabio Simeoni
featherweight clients
a skinny stack for calling the infrastructure
TCOM
Wednesday, 23 January 13

2
outline
know thy clients
fat stacks
• gcore & gcore ‘redux
a sKINNY stack
• stubs, resources, IS clients
Skinny CLs
• framework support
Done-s &todo-s

3
clients
external
clients
infrastructure
GCUBE
service
INTERNaL
clients
client
stack
bad stacks can harm uptake
bad stacks can harm evolution
portlets
services
tools
WHAT's a bad stack ?
bad stacks can harm management

4
gcore STacks

5
full gcore stack
AXIS
globus
gcore
JDK
CLIENT
FAT
SKINNY
DEPS
~ 24 MB
client library
service STUBS
2004-2012

6
main issues
• awkward
• installed & configured on file system
no declarative management (e.g. via maven)
no embedding (e.g. in web-app)
• needlessly faT
• about 140 jars, only a fraction relevant
no cherry picking: unclear dependency graph
service-side bias: high “clash-factor”
• obsolete
• 2004 and older
• age increases further “clash factor”

7
retrospective
• a service stack, really
• pure client support is an afterthought
• oK if cLIents =gcore services
• issues become non-issues (e.g. install,config)
• ...or are platform issues (e.g. obsolete)
• a toothache otherwise
• unpresentable to external clients
• won’t let us develop internal clients on new platforms
adoption & evolution at stake

8
gcore “redux” stack
AXIS subset
globus subset
gcore subset
JDK
ghn-client-runtime
client library
CLIENT
FAT
SKINNY
~10 MB
service STUBS
2012-

9
how it works
• a subset of the gcore stack
• prunes what clients don’t need
• fully mavenized
• in gcube-externals, as closure of ghn-client-runtime
• embeds a teeny-tiny ghn distro
• just config files, including all servicemaps
• unpacks it on demand
• in temp folder, when client says so (CLientruntime#start())

10
properties
• friendlier
• hides FS installation&configuration requirements
automated dependency management now possible
embedding now possible
• leaner
• about 40jars, all relevant
client-only bias reduces “clash-factor”
• but...
still obsolete, it’s just a subset
still large, cherry picking remains unlikely
usage is not transparent (client must bootstrap)
just a clever hack

11
a new STack

12
why do we need...
• ...axis ?
• stubs depend on it
• implements ws-addressing
• ...Globus ?
• stubs depend on it
• gcore depends on it
• ....Gcore ?
• again, stubs depend on it
• knows how to manage scope
• knows how to make “gcore calls”
• knows how to model, discover, publish resources

13
Nov-Dec 2012
• fao shows clients don’t need axis stubs
• uses interfaces annotated with JAX-WS&JAXB
• JDK 6+implements them on-the-fly
• FAO proposes a new stack
• gcore-free, built on pure JDK support, lean
• CNR, CERN & ATHENS approve
• FAO&CNR deliver it in 2 weeks (“botox”)
• implement scope and call support outside gcore
• implement resources, discovery & publication outside
gcore
• add novelties in the process

14
featherweight stack
models
resources
IC-independent
model-independent
layer
discovers
resources
with Collector
publishes
resources
with registry
common-SCOPE
common-SCOPE-MAPs
common-gcore-stubs
JAX-WS
JDK
JAXB
regiStry-STUBS
registry-publisher
IC-STUBS
IC-CLIENT
common-gcore-RESOURCES
DISCOVERY-CLIENT
turns CALLS
into gcore calls
manages
call scope
manages
scope
configuration
8KB
20KB
20KB
16KB
160KB
16KB
24KB

15
featherweight stack
JDK CALLS
client library
CLIENT
FAT
SKINNY
<1 MB
2013-
DISCOVERY
RESOURCES
SCOPE
PUBLICATION

16
properties
• “normal”
• no FS installation or configuration
• no bootstrapping requirements
• maven-based, easily embedded
• skinny & standard
• less than 10jars, almost no 3rd party deps
• jdk provides runtime, parser, binding, etc.
• zero “clash-factor”
• modular
• calls without discovery & publication
• discovery without publication
• publication without discovery

17
more info...

18
the new STUBS

19
properties
• distribution
• a pure client-side artifact
• most likely embedded in cl, if one exists
• contents
• the “SEI”: stub interface, ann. with jax-ws
• i/o bean classes, ann. with jaxb
• handful of service-specific constants
• no SEI implementation, locators, ...
• development
• can be (largely) automated
• can be (fully) manual (more than doable)
• not a client concern !

20
the ACME service
WSDL
<definitions name="Acme"
targetNamespace="http://acme.org" ... >

! ......

" <portType name="AcmePortType">

...

" </portType>

...

<service name="s:AcmeService" xlmns:s="http://acme.org/service">
...
</service>

</definitions>
class AcmeConstants {
static final String serviceNS = "http://acme.org/service";
static final String porttypeNS = "http://acme.org";
static final QName name = new QName(serviceNS,"AcmeService");
static final String porttypeLN = "AcmePortType";
static final String gcube_class="VIPServices";
static final String gcube_name="Acme";
}
ACME
service
PROFILE
<Resource>
….
<Profile>
<Class>VIPServices</Class>
<Name>Acme</Name>
….
</Profile>
</Resource>
gCube
coordinates
web service
coordinates
constants

21
ACME SEI
@WebService(name=porttypeLN,
targetNamespace=porttypeNS)
public interface AcmeStub {
@SOAPBinding(parameterStyle=BARE)
String foo(String s);
...
}
WSDL
<definitions name="Acme"
targetNamespace="http://acme.org" … >

<types>
<xsd:schema targetNamespace="http://acme.org">

<xsd:element name="foo" type="xsd:string" />
<xsd:element name="fooResponse" type="xsd:string" />

...
</xsd:schema>
</types>

...
<portType name="AcmePortType">

<operation name="foo">
<input message="tns:foo"/>
<output message="tns:fooResponse"/>
</operation>

...

</portType>

...

</definitions>
JAX-WS SEI
MANUAL or AUTOMATic
GENERATION
complex I/O require
JAxB-ANNOTATED BEANS
WIKI TUTORIAL AVAILABLE

22
ACME descriptor
import static org.gcube.common.clients.stubs.jaxws.GCoreServiceBuilder.*;
class AcmeConstants {
static final String serviceNS = "http://acme.org/service";
static final String porttypeNS = "http://acme.org";
static final QName name = new QName(serviceNS,"AcmeService");
static final String porttypeLN = "AcmePortType";
static final String gcube_class="VIPServices";
static final String gcube_name="Acme";
static final GCoreService<AcmeStub> acme = service().
withName(name).
coordinates(gcube_class,gcube_name).
andInterface(AcmeStub.class);
}
constants

23
more info...

24
making calls

25
at a glance
SEI
STUBS
common-gcore-stubs
DESCRIPTOR ENDPOINT
address
URI or reference
returns STUB
IMPLEMENTATION
for client use
FETCHES WSDL
from service endpoint
(NET or cache)
obtains STUB
implementation
from jaws runtime
configures stubs
to make "gore calls"
to service endpoint

26
in code
import static …AcmeConstants.*;
import static org.gcube.common.clients.stubs.jaxws.StubFactory.*;
...
//some endpoint address
URI address = ...
//get a stub
MyStub stub = stubFor(acme).at(address);
//use stub
String outcome = stub.foo("...");

27
more info...

28
binding
resources

29
at a glance
resourcecommon-gcore-RESOURCES
describes
describes
reads &
writes
creates &
inspects object
profile

30
model classes
• HostingNode
• Software : services, libs, plugins
• ex. gcube service
• GcoreEndpoint
• ex. Running instance
• ServiceEndpoint : endpoints of non-gcore services
• ex. Runtime resource
• ServiceInstance : instances of (stateful) gcore services
• ex. resource property document
• GenericResource: any other resource

31
what’s new
• standard data binding
• now based on jaxb’s ri in JDK
• explicit alidation
• now exposed to clients
• no longer implicit AT binding time
• more regularity
• consistent API across property types
• equals() & hashcode() throughout
• less ad-hoc provisions (for good or bad)

32
what’s new
• more FLUENCY
• builder-style construction
• inlined creation
• less temp vars, less new() operators
• minimality
• e.g. no scope checks
• e.g. no encryption
• ...
• no logic beyond access & binding

33
read example
import static org.gcube.common.resources.gcore.Resources.*;
//bind
GCoreEndpoint endpoint =
unmarshal(GCoreEndpoint.class,...one of many sources...);
print(endpoint);
Element data = endpoint.profile().specificData();
//helper
XPathHelper xpath = new XPathHelper(data);
for (String p : xpath.evaluate("/my/prop")
...

34
write example
import static org.gcube.common.resources.gcore.Resources.*;
GCoreEndpoint endpoint = new GCoreEndpoint();
endpoint.scopes().add("/some/scope");
//fluent building
endpoint.profile().version("345").
ghnId("nodeid").
serviceId("serviceid").
serviceName("name").
serviceClass("class");
//inlined creation
endpoint.profile().newDeploymentData().
activationTime(Calendar.getInstance());
//inlined element creation
endpoint.profile().endpoints().add().nameAndAddress("name",...);
validate (endpoint);
//bind
marshal(GCoreEndpoint.class,...one of many sinks...);

35
more info...

36
discovering
resources

37
at a glance
IC-STUBS
IC-CLIENT
INformation
collector
query
result
parser
submit
parse
parsed
results

38
what’s new
• same core pattern
• prepare query beans, free-form or templated
• submit beans, get parsed results
• more modular
• queries don’t do parsing
• parser defined at submission
• can parse fine-grained results
• predefined parsers for all resource props
• more flexible templates
• results, variables, namespaces
• query templating not only for internal use

39
featherweight
client libraries

40
predeﬁned queries
import static org.gcube.resources.discovery.icclient.ICFactory.*;
//pick a predefined query
Query query = queryFor(ServiceEndpoint.class);

//pick client that knows how to parse those resources
DiscoveryClient<ServiceEndpoint> client = clientFor(ServiceEndpoint.class);

//execute query in current scope
List<ServiceEndpoint> endpoints = client.submit(query);
//consume results
...

41
conditions and results
SimpleQuery query = queryFor(ServiceEndpoint.class);
//customise query to return only database endpoints
query.addCondition("$resource/Profile/Category/text() eq 'Database'")
.setResult("$resource/Profile/AccessPoint/Interface/Endpoint/text()");

//client that does not parse
DiscoveryClient<String> client = client();

List<String> endpoints = client.submit(query);


42
aux variables
SimpleQuery query = queryFor(GCoreEndpoint.class);
//customise to return only some endpoints
query.addCondition("$resource/Profile/ServiceName/text() eq 'tree-manager-service'")
.addVariable("$entry","$resource/Profile/AccessPoint/RunningInstanceInterfaces/Endpoint");
.addCondition("$entry/@EntryName/string() eq 'gcube/data/tm/binder'");
.setResult("$entry/text()");
//client that does not parse

List<String> entries = client.submit(query);


43
custom namespaces
SimpleQuery query = queryFor(ServiceInstance.class);
URI uri = URI.create("http://gcube-system.org/namespaces/data/tm"));
query.addNamespace("tm",uri)
.addCondition("$resource/Data/tm:Plugin/name/text() eq '...'");
//client that parses instances
DiscoveryClient<ServiceInstance> client = clientFor(ServiceInstance.class);

List<ServiceInstance> instances = client.submit(query);


44
property JAXB parsers
.setResult("$resource/Profile/AccessPoint");
//client that parses access points
DiscoveryClient<AccessPoint> client = clientFor(AccessPoint.class);

List<AccessPoint> apoints = client.submit(query);


45
custom JAXB parsers
//customise to return property selection
.query.setResult("<perfect>" +
“<id>{$resource/ID/text()}</id>" +
"{$resource/Profile/AccessPoint}" +
"</perfect>");
DiscoveryClient<AccessPoint> client = clientFor(PerfectResult.class);
List<PerfectResult > results = client.submit(query);
---------------------------------------------------------------------------------
@XmlRootElement(name="perfect")
private static class PerfectResult {
@XmlElement(name="id") String id;
@XmlElementRef AccessPoint ap;
}

46
free-form queries
QueryBox query = new QueryBox(“...expression...”);
List<String> results = client.submit(query);

47
more info...

48
featherweight
client libraries

49
client libraries
client library
any cLIENT stack
client
discover call

50
gCore CLs
common-clients
common-gcore-clients
gCore
CL
other
cl deps
abstract
layer
gcore
binding
gcore stack

51
“pick a feather”
client library
GCORE stack
client
featherweight
stack
migration
version x.y.z version x.y+1

52
featherweight CLs
common-clients
common-FW-clients
gCore
CL
other
cl deps
abstract
layer
FWS
binding
featherweight
stack
NEW !
jaxws-
stubs

53
more info...

54
dones & todos

55
dones
• components
• all components
• cl framework binding
• documentation (almost) complete
• client migration
• tree manager library
• data transfer library
• search library
• species service library
• tree-uri-resolver

56
to-do
• known issues
• faults do not carry remote stacktrace
• cl FWk does not set timeouts, yet
• last few 3rd party deps not perfect
• components
• migrate encryption
• notifications ? how ?

57
conclusions
• gcore is quarantined
• only service-side
• calling gcube has become easy
• and leaves the smallest footprint
• gcube can evolve
• future services can target modern platforms
• enabling work can start to support them
• without painful, all-or-nothing migrations

Featherweight Clients (Athens, 2012)

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