System Introspection for System Analysis on Mobile Devices

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implementation of the designed communication interface. Messages betweenthe probe and the client are exchanged via a communication server.Figure 5.1: Overview of the designed architecture - On the left sideis the robot providing its components by using the Bon-SAI interface. Probe and client are connected via thecommunication server.5.1 Communication InterfaceTo handle the communication between the probe and the client a communicationinterface is designed to be implemented on the different entities. The ideabehind the interface is to capsule all needed communication overhead to thisinterface. Also by implementing the interface on both systems the same understandingof message exchange is guaranteed. The communication interfacecontrols the in<strong>for</strong>mation flow between connected entities and the communicationserver. The main functionalities that are needed are establishing aconnection to the communication server and the exchange of messages amongconnected entities. A handshake mechanism by sending a message and waiting<strong>for</strong> a response is used to acknowledge the connection between two entities. Tomonitor the connection between the entities a beacon is used. This beaconmust be exchanged to assure that both sides are available.Entities in this thesis are the probe and the client. At startup both entitiesmust connect to a connection server by using a connection configuration. Theconfiguration is distinguished from the source by using a configuration file.When the client is connected it sends a message to the probe requesting toestablish a communication channel. The probe acknowledges the request andadds the client to a list of known clients. This list is held by the probe <strong>for</strong>a whole runtime. Once the connection between probe and client is created,the client can request data of component threads controlled by the probe. Requestsare <strong>for</strong>warded to the components which send data to the client. Figure5.2 shows how a message is created and transferred from the probe over acommunication server to the client.21
Figure 5.2: Message exchange between probe and client - On theleft side is the component thread publishing new data <strong>for</strong>connected clients. The data is send to the communicationinterface that handles all the communication withthe communication server. The server itself <strong>for</strong>wards themessage to the client. The communication interface onthe client side notifies all observers. Each observer thenchecks the message and processes it if needed.Using Publish / SubscribeThe mechanism behind exchanging the data is using the publish/subscribeparadigm (Eugster et al., 2003). One entity subscribes to a publisher. Thepublisher collects data and <strong>for</strong>wards it to all subscribers. The probe offersservices and publishes their data on request. The client can subscribe to sucha service. In contrast to a standard implementation of the publish/subscribeparadigm the publisher also knows the subscriber and vise versa. A componentthread is not only acting as a publisher. Each component thread can alsoreceive commands which can change how the data is published. These commandsmay also change the state of a component thread. An example couldbe a component that has several parameters <strong>for</strong> changing the process of filteringthe data presented. The client knows the publisher and can directly sendcommands. Also this can be used to minimize the need of control overheadand decrease the delay between sending and receiving a command. Specificcommands are <strong>for</strong>warded to a component thread which can directly use thecommands <strong>for</strong> further processing.To notify entities of incoming messages, the communication interface is usingthe observer pattern (Freeman et al. (2004), pages 37-78). For the exchange ofdata between the probe and the client, each message created contains the TAGof the sending element and the TAG of the component that receives the data.A TAG is unique to the system and allows to identify its elements. Whenevera new message is received, the interface notifies its observers. Each elementobserving this interface checks if the message contains its TAG and then reads22
Page 1: Bringing System <s
Page 5 and 6: AbstractSystem <st
Page 7 and 8: output, so each component is offeri
Page 9 and 10: of the system and the decisions mad
Page 11 and 12: created a telelaboratory where two
Page 13 and 14: Like the telelaboratory there is a
Page 15 and 16: with a very high frequency which ma
Page 17 and 18: Due to improving technology the use
Page 19 and 20: Figure 4.1: ToBI platfor</s
Page 21 and 22: Figure 4.3: The architecture behind
Page 23 and 24: Figure 4.5: Typical instant messagi
Page 25: 5 System DesignThe
Page 29 and 30: Figure 5.4: Beacon running between
Page 31 and 32: Figure 5.5: Reading and processing
Page 33 and 34: data and only forw
Page 35 and 36: For example a developer can select
Page 37 and 38: Figure 5.13: Principle of tabbed na
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Page 45 and 46: is received containing the TAG of t
Page 47 and 48: The selected sensors give a good im
Page 49 and 50: 1 2 4 6 8 Listing 6.2: Example of t
Page 51 and 52: TabConfig - The Status ViewThe TabC
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Page 55 and 56: LoginController which also observes
Page 57 and 58: tends the JPanel class. The templat
Page 59 and 60: 7 EvaluationIn the previous chapter
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Page 63 and 64: Figure 7.1: Latency of receiving da
Page 65 and 66: For this thesis only a rough estima
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Page 69 and 70: 8 ConclusionsIn the context of this
Page 71 and 72: 9 OutlookGiven this new tool its no
Page 74: BibliographyBurrell, A. and A. Soda
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6.10 Main classes of the Java clien
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AppendixUse CasesUse Case 1: Connec
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Use Case 4: Disconnect from compone
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Use Case 9: Sending beacon to keep
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Figure 9.4: Latency of receiving da
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System Introspection for System Analysis on Mobile Devices

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