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Minutes of Meeting, 13/11/2000 @ 9:00 |
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Location: UKC Computer Science Meeting Room |
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Present: ab11, pjm2, tdb1 |
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Absent: ajm4 |
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The communications between host and server were discussed |
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yet again. Paul argued that the TCP communications were |
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unnecessary, and UDP would suffice. Tim pointed out that the |
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general unreliability of UDP would make it hard for the |
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system to know whether a host had actually gone down, or |
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whether it was a network problem. Tim also pointed out that |
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the UDP packets may require sequencing, so the server knows |
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whether packets were missed - for alerting purposes. |
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In the end it was decided that a combination would be used, |
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with TCP used for heartbeats alongside the regular UDP |
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communications. Different alerts could be raised depending |
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on whether UDP packets weren't arriving, or the TCP |
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heartbeat fails (the latter being considered worse). |
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Discussion continued with Paul outlining the basic situation |
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with XML parsing. It was noted that various external java |
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classes would be required for parsing (SAX, and javax...). |
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This should not be a problem. |
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Finally the XMLPacket was discussed. It was noted that the |
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XML data must somehow be laid out in the XMLPacket, |
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retaining it's structure. The following was suggested, with |
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the data being stored as tuples in the XMLPacket. |
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[XML] |
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<data> |
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<value1>val1</value1> |
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<sub1> |
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<value2>val2</value2> |
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<value3>val3</value3> |
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</sub1> |
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</data> |
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[XMLPacket] |
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"data.value1", "val1" |
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"data.sub1.value2", "val2" |
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"data.sub1.value3", "val3" |
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This format makes it easy for the "end client" to extract |
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information, only knowing the format of the XML data. This |
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helps to ensure consistency across the system. |
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It was decided that some kind of Hash would be the quickest |
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way of storing (and accessing) these tuples of data. The |
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group agreed this idea would be best. |
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The lifetime and location of the XMLPacket is still an |
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uncertain area. We must ensure they are left for the Garbage |
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Collector when they are finished with. |
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Prior to the next meeting Paul will continue to investigate |
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the XML parsing, and work on that side of the Filter. Ash |
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will continue work on the host side (still in Java). AJ & |
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Tim will collaborate on the FilterManager, ParentFilter, and |
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possibly the CORBA side of Paul's filter system. |
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Finally, the group members (that were present) voted |
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unanimously that AJ will be doing the hard parts of the C++ |
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bits in the host. :) |
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Meeting was concluded @ 11:00. Next meeting booked for 11:00 |
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on Wednesday, until 12:30. Meeting with iau @ 13:30 on that |
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day. |
