System Introspection for System Analysis on Mobile Devices

More documents

Recommendations

Info

and processes the data. Each observer is inactive as long as no messages are<strong>for</strong>warded. This allows the system to save resources normally used <strong>for</strong> activelymonitoring the communication (e.g. polling). Component threads do not needto permanently check if new messages have arrived. Figure 5.3 shows thecommunication flow by using the observer pattern.Figure 5.3: Communication flow with observer pattern - The communicationinterface listens to new messages from thecommunication server. New messages are <strong>for</strong>warded tothe interface. Once received, the interface notifies all observers.Each observer checks the message and processesthe data if needed.Monitoring the ConnectionTo assure that the connection between probe and client is permanently alive,a monitoring system is needed. To monitor the connection a beacon system isused. Henry et al. (1998) used a beacon to monitor the state of a spacecraft.The spacecraft sends tones with defined frequencies. From this frequency thestate of the spacecraft can be derived. For this thesis a similar approach is used.The idea of a beacon was to save system resources if the connection betweenthe probe and the client got lost. A beacon allows the probe to monitor theconnection to each client with minimal effect on the connection itself. Whenthe client connects to the probe, the probe will send a beacon to the client in agiven frequency. The client has to answer the beacon by sending a new beaconto the probe. This technique offers several advantages. It allows the probeto manage its component threads. If a client is disconnected due to missingbeacons all component threads sending data to the client can be notified aboutthe disconnect. Besides the beacon that is transferred additionally contains atimestamp, which allows to check the round-trip time between probe and client.It can also be used to synchronize the time on both systems. For example theprobe can act as time giver and provide its time to all connected clients. Figure5.4 shows the sequence of a single beacon exchange.23
Figure 5.4: Beacon running between probe and client - The probesends a beacon with a given frequency and waits <strong>for</strong> ananswer. When the client receives the beacon it sends ananswer in return.5.2 Probe - The Server SideThe probe is attached to the software of a robot and acts like a server publishingdata of the components of the robot. This data can be live observed byrequesting a component thread publishing its in<strong>for</strong>mation or logged to the filesystem <strong>for</strong> post-hoc-analysis. Two main features can be defined as followed:Live ObservationLogging Cyclecollects data of a component of the robot and<strong>for</strong>wards the data packed into messages to connectedclientscollects data of selected components and savesthem with a timestamp on the file system of theprobeFor both features several elements are needed to control the processes betweenprobe and connected clients. The probe implements the communicationinterface and every element of the probe observes the implementation. Theelements on the probe are using several lists to monitor which client is connectedto which element. Also some configurations can be applied by using aconfiguration file placed on the file system the probe. There are four controlelements designed <strong>for</strong> the probe:24
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 and 26: 5 System DesignThe
Page 27: Figure 5.2: Message exchange betwee
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
Page 39 and 40: 6.1 The Communication InterfaceThe
Page 41 and 42: 6.2 The Probe - Implementation of t
Page 43 and 44: stop all active processes of the co
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
Page 53 and 54: Each view adds a listener to the co
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
Page 61 and 62: Name Description CharactersSingleli
Page 63 and 64: Figure 7.1: Latency of receiving da
Page 65 and 66: For this thesis only a rough estima
Page 67 and 68: Laptop CPU load without Probe CPU l
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
Page 77 and 78: 6.10 Main classes of the Java clien
Page 79 and 80:
AppendixUse CasesUse Case 1: Connec
Page 81 and 82:
Use Case 4: Disconnect from compone
Page 83 and 84:
Use Case 9: Sending beacon to keep
Page 85 and 86:
Figure 9.4: Latency of receiving da
show all

System Introspection for System Analysis on Mobile Devices

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?