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Fig. 4. Web Service Invocationretrieve, update, delete) pattern. This means that dierent HTTP methodtypes should be used depending on the action that should be executed on aweb resource. Mapping these types from a method signature is hardly possibleas the method semantics is not available to the mapper. Nevertheless,using other HTTP methods than originally intended is not prohibited perse. Possible negative eects that may arise concern eciency as some ofthe method types are considered being idempotent so that existing HTTPcaching can further be used.The architecture of the REST publisher is more complex than the WSDL publisher.It partitions work into two phases. In the rst phase the given componentservice interface is analyzed with respect to the methods that should be generatedand how these should be represented in REST (according to the descriptionsabove). The result is a list of methods with exact descriptions how these methodsshould be created in REST. This list is passed on to the second stage inwhich a Java class is generated for the REST service via bytecode engineering.The generator rst creates Java method signatures using the method name andparameter types produced in the rst phase. Afterwards, it creates Java annotationsfor the REST specic mapping information according to the JAX-RSspecication 5 . The publisher can directly pass this class to the REST container,which ensures that the service is made available.3.2 Integrating Existing Web ServicesIntegrating web services aims at making usable existing functionalities as componentservices (cf. Fig. 4). In this way access to external functionalities can bemasked and be used in the same way as other middleware services. Challengesin this integration are mainly limited to the question how an external servicecan be adequately mapped to the middleware and how it can be made accessibleto service clients. The conceptual approach chosen is based on wrapper components,which act as internal service providers for the external functionality.A wrapper component oers the external functionality as provided service with5 http://jax-rs-spec.java.net/29
an interface that on the one hand mimics the original service interface and onthe other hand complies to the asynchronous requirements of the middleware,i.e. in the simplest case the internal interface is the asynchronous version of theexternal interface. The implementation of the provided service is representedby a specic forward mechanism that dispatches the call to the external webservice. To resolve the synchronous/asynchronous mismatch a decoupled invocationcomponent is used. For each service call such an invocation component iscreated, which is solely responsible to perform the synchronous operation. Whilethe operation is pending the invocation component remains blocked but as it hasno other duties than performing the call this is not troublesome. This patternkeeps the wrapper component responsive and lets it accepting concurrent serviceinvocations without having to wait until the previous call has returned.WSDL Wrapper The WSDL wrapper component heavily relies on the existingJAX-WS technology stack. 6 One core element of this stack is a tool calledwsimport that is used to automatically generate Java data and service classesfor a given WSDL URL. The generated code can directly be used to invoke theweb service from Java. Based on this generated code the asynchronous serviceinterface has to be manually dened relying on the generated data types forparameters. For this reason no further parameter mappings need to be dened.The wrapper component itself declares a provided service with this interface anduses a framework call to dynamically create the service implementation.REST Wrapper The REST wrapper is based on JAX-RS technology but currentlydoes not employ automatic code generation. 7 Instead, the asynchronouscomponent service interface has to be created manually based on the RESTservice documentation. The interface denition should abstract away from theREST resource architecture and give it a normal object oriented view. The mappingof the component service towards the REST service is done with a mappingle represented as annotated interface. This annotated interface containsall methods of the original service interface and adds mapping information forthe same types of information that already have been used for publishing, i.e.for each method the URL for the REST call, the consumed and produced mediatypes, parameter and result mappings as well as the HTTP method type. Thewrapper component denition is done analogously to the WSDL version withone dierence. Instead of using a generated service implementation, the RESTwrapper uses a dynamic proxy that uses the mapping interface to create suitableREST invocations.6 http://jax-ws.java.net/7Automatic code generation can only be used for REST services that supply a webapplication description (WADL le) of themselves that represents the pendant to theWSDL le of an XML web service. Similar to wsimport, a tool called wadl2java isavailable that is able to create Java classes for data types and services of the RESTservice. A problem is that WADL has not reached W3C standard status and also isnot in widespread use in practice.30
Page 2 and 3: Proceedings of the Tenth Internatio
Page 4 and 5: OrganisationOrganising CommitteeMeh
Page 6: Table of ContentseJason: an impleme
Page 10 and 11: in Sect. 3 the translation of the J
Page 12 and 13: init_count(0).max_count(2000).(a)(b
Page 14 and 15: For instance, a failure in the ERES
Page 16 and 17: {plan, fun start_count_trigger/1,fu
Page 18 and 19: single parameter, an Erlang record
Page 20 and 21: 1. Belief annotations. Even though
Page 22 and 23: decisions taken during the design a
Page 24 and 25: Conceptual Integration of Agents wi
Page 26 and 27: Fig. 2. Active component structurep
Page 28 and 29: the service provider component. As
Page 32 and 33: 01: public interface IBankingServic
Page 34 and 35: tate them in the same way as in the
Page 36 and 37: 01: public interface IChartService
Page 38 and 39: implementations being available for
Page 41: deliberative behavior in BDI archit
Page 44 and 45: layer modules (i.e. nodes) can be d
Page 46 and 47: different methods to choose the cur
Page 48 and 49: also a single scheduler module, imp
Page 50 and 51: andom choice (OR), conditional choi
Page 52 and 53: - Dealing with conflicts based on p
Page 54 and 55: 5. Brooks, R. A. (1991) Intelligenc
Page 56 and 57: An Agent-Based Cognitive Robot Arch
Page 58 and 59: It has been argued that building ro
Page 60 and 61: EnvironmentHardwareLocal SoftwareC+
Page 62 and 63: a cognitive layer can connect as a
Page 64 and 65: can reliably be differentiated and
Page 66 and 67: 4 ExperimentTo evaluate the feasibi
Page 68 and 69: learn or gain knowledge from experi
Page 70 and 71: A Programming Framework for Multi-A
Page 72 and 73: exchange and storage of tuples (key
Page 74 and 75: Although some success [13] [14] hav
Page 76 and 77: as well as important non-functional
Page 78 and 79: component plans have been instantia
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A in the example) can evaluate all
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1. robot-1 issues a Localization(ro
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ACKNOWLEDGMENTThis work has been su
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The code was analysed both objectiv
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a conversation is following. Additi
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the context of a communication-heav
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Table 1. Core Agent ProtocolsAgent
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statistically significant using an
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to the conversation and has a perfo
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principal reasons. Firstly, it is a
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2. Muldoon, C., O’Hare, G.M.P., C
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In the following section we will at
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DevelopmentProductionHuman Readabil
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will then evaluate this new format
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encoder, it is first checked if the
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nents themselves. However, since th
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optimized for this format feature s
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Java serialization and Jadex Binary
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10. P. Hoffman and F. Yergeau, “U
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Caching the results of previous que
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querying an agent’s beliefs and g
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or relative performance of each pla
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were run for 1.5 minutes; 1.5 minut
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Size N K n p c qry U c upd Update c
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epresentation. The cache simply act
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6 ConclusionWe presented an abstrac
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Typing Multi-Agent Programs in simp
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1 // agent ag02 iterations (" zero
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3.1 simpAL OverviewThe main inspira
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3.2 Typing Agents with Tasks and Ro
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Defining Agent Scripts in simpAL (F
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that sends a message to the receive
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* error: wrong type for the param v
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Given an organization model, it is
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Learning to Improve Agent Behaviour
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2.1 Agent Programming LanguagesAgen
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choosing actions is to find a good
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1 init module {2 knowledge{3 block(
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of a module. For example, to change
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if bel(on(X,Y), clear(X)), a-goal(c
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mance. Figure 2d shows the same A f
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the current percepts of the agent.
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Author IndexAbdel-Naby, S., 69Alelc
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