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Data gathering scenario:
The 2 gathering options:
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Options
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Generalized options
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1
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Periodic listening, on changes for example in the SVN case listening for a commit.
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A Listening component needs an extra module in the target systems.
For further use we call it, periodic listening.
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2
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Using different libraries, API’S or connector per tool type. This will be also periodically.
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Database connection, SOA interface to gather the data directly from the database, or a SVN library to gather the SVN stats.
For further use we call it, periodic queries.
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The options above can be also applied on the other system adaptors.
Advantages between periodic listening and periodic queries:
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Periodic listening
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Periodically direct queries
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Advantage
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Description
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Advantage
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Description
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Small requests
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To listen on commits produce only small requests.
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Use of given and common ways to query the source systems.
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For example with direct database connections, or a SVN library to gather the stats.
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Free libraries and connectors mostly given.
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The SVN or database connectors for open source systems are mostly free to use.
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Disadvantages between periodic listening and periodic queries:
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Periodic listening
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Periodically direct queries
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Disadvantage
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Description
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Disadvantage
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Description
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A lot of requests to gather the needed information.
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Produces overhead.
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Need change for data access changes
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For example when the wiki always used a MYSQL database and the database gets changed to ORACLE the connector needs to be reconfigured.
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In other cases an extra plug-in need to be installed in the source systems to listen on changes.
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Produces overhead and extra costs and administration for the administrator of the system. (Updates etc.)
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Conclusion:
The conclusion is to use the query variant, because it uses given technologies without needed changes on the source systems. These techniques can be used for every source system. For example for the SVN with a simulated client or API calls, or in the WIKI case with read access on the Node database structure from the WIKI database.
Decision:
The second option the periodic query option can be used for every SVN server, Database or given API from the source systems and its fits the requested extensibility attribute. Can be used for SVN and in this range for every SVN related Server implementation. Mature Lib's are available to provide a secure and reliable wayretrieving data from SVN Repositories, databases or email, IRC communication channels. The use of connector classes can be made configurable to eliminate the named disadvantage for this option.
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21 Appendix - Data gathering scenario
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