Difference between revisions of "WebFund 2016W: Assignment 4"

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(Created page with "'''This assignment is still being developed.''' In this assignment you will create <tt>queryLogs.js</tt>, a program that will query the logs collection in the log-demo databa...")
 
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queryLogs.js should be called as follows:
queryLogs.js should be called as follows:


   node queryLogs.js [--output=<output file>] [--maxcount=<max number of documents to return>]  <criteria> [<projection>]
   node queryLogs.js [--results=<output file>] [--maxcount=<max number of documents to return>]  [--service="service query"]
      [--message="message query"]


Here is an example of a query that includes all the options:
Here is an example of a query that includes all the options:


   node queryLogs.js --output=out.txt --maxcount=10 '{"date": "Feb 17"}' '{"message": 1}'
   node queryLogs.js --results=out.txt --maxcount=10 --service="systemd" --message="[Ss]tarted"  


The above would return at most 10 matching documents and output them to out.txt. The documents would consist of all those with a date of "Feb 17", with only the message field being returned (i.e, the projection). The format of the output should be the same as the format returned from calling toArray on the [http://docs.mongodb.org/manual/reference/method/db.collection.find/ find()] query (see Key Logic below)  - an array of JSON objects.
The above would return at most 10 matching log messages and output them to out.txt. The log lines should be outputted as lines, not as objects (i.e., they should appear as they were before being stored in the database). The service and message queries should both be regular expressions and should be combined with a logical and if both are present.


===Arguments===
Note that all arguments are optional.  If neither --service or --message are specified, all stored log messages should be returned (up to --maxcount, if specified). If no --maxcount is specified, all matching records should be output. If no --results is specified, the output should go to standard out.  Thus, node queryLogs.js can be called with no arguments and should just dump all of the log messages (albeit potentially in an arbitrary order).
* The query is mandatory.  It should be a single string that follows the syntax of a [http://docs.mongodb.org/manual/reference/method/db.collection.find/ find() criteria object] except that the enclosing curly braces are optional.
* The output file should default to standard out.
* If no maxcount is specified then all matching documents should be returned.
* The projection should default to all fields.  The enclosing braces on the object should also be optional.


===Key logic===
===Scoring===
To process the query and projection strings you should:
* add enclosing curly braces if they are not present,
* convert the string to an object using [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse JSON.parse()], and then
* create a cursor object using [http://docs.mongodb.org/manual/reference/method/db.collection.find/ find()], giving it the supplied criteria and optionally the projection object, and
* retrieve all of the objects using toArray() on the cursor object (see examples of toArray() [https://www.npmjs.com/package/mongodb here]).
* report an error message to standard error saying "Error..." (start with the word Error and say whatever afterwards) if there are any problems with the operation.


===Scoring===
Points will be awarded as follows:
Points will be awarded as follows:
* 3 for doing the default find() properly using a query with braces
* 2 for --results
* 1 for handling missing curly braces
* 2 for --maxcount
* 1 for --output working properly
* 2 for --service
* 2 for limiting the records correctly
* 2 for --message
* 2 for the projection (returning only certain fields)
* 2 for functionality with missing arguments
* 1 for handling missing or malformed queries
Total: 10 points
Total: 10 points

Revision as of 15:26, 24 February 2016

This assignment is still being developed.

In this assignment you will create queryLogs.js, a program that will query the logs collection in the log-demo database for matching log entries. Please submit your answers as a single JavaScript source file called "<username>-queryLogs.js" (where username is your MyCarletonOne username). Please do not submit a zip file (i.e., no need for a node_modules directory).

In total, there are 10 points. The questions below will be automatically graded, so please follow the directions carefully.

This assignment is due March 2, 2016.

Syntax

queryLogs.js should be called as follows: 

 node queryLogs.js [--results=<output file>] [--maxcount=<max number of documents to return>]  [--service="service query"]
     [--message="message query"]

Here is an example of a query that includes all the options: 

 node queryLogs.js --results=out.txt --maxcount=10 --service="systemd" --message="[Ss]tarted"

The above would return at most 10 matching log messages and output them to out.txt. The log lines should be outputted as lines, not as objects (i.e., they should appear as they were before being stored in the database). The service and message queries should both be regular expressions and should be combined with a logical and if both are present.

Note that all arguments are optional. If neither --service or --message are specified, all stored log messages should be returned (up to --maxcount, if specified). If no --maxcount is specified, all matching records should be output. If no --results is specified, the output should go to standard out. Thus, node queryLogs.js can be called with no arguments and should just dump all of the log messages (albeit potentially in an arbitrary order).

Scoring

Points will be awarded as follows:

  • 2 for --results
  • 2 for --maxcount
  • 2 for --service
  • 2 for --message
  • 2 for functionality with missing arguments

Total: 10 points

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