On Thu, Jun 27, 2013 at 4:26 AM, Ian Boston <i...@tfd.co.uk> wrote:
> On 27 June 2013 02:34, Dishara Wijewardana <ddwijeward...@gmail.com>
> wrote:
>
> > On Tue, Jun 25, 2013 at 4:52 AM, Ian Boston <i...@tfd.co.uk> wrote:
> >
> > > Hi,
> > >
> > > (I might have errors in the CQL, Cassandra schema and the functions
> need
> > > proper escaping)
> > >
> > >
> > > Example 1:
> > > Zero depth tree wiht UUID as the rowid or key.
> > >
> > > URL /content/cassandra/pictures/13f58d5c95c70b6f
> > >
> > > then the column family is pictures and the URL -> ROWID function just
> > > results in the ROWID being 13f58d5c95c70b6f and
> > >
> > > String cql = mapOfCassandraMappers.get("pictures").getCQL("pictures", "
> > > 13f58d5c95c70b6f")
> > > System.err.println(cql);
> > >
> > > where
> > > String getCQL(String cf, String path) {
> > > return "select * from "+cf+" where rowid = '"+path+"'";
> > > }
> > >
> > > yields:
> > > select * from pictures where rowid = '13f58d5c95c70b6f'
> > >
> > >
> > > 13f58d5c95c70b6f would be generated by the application when the user
> > > created a new picture (by upload).
> > >
> > >
> > >
> > > Example 2:
> > > User specified
> > >
> > > URL /content/cassandra/catalogue/capacitors/electrolytic/axial/16v/10uf
> > >
> > > String cql =
> mapOfCassandraMappers.get("catalogue").getCQL("catalogue", "
> > > capacitors/electrolytic/axial/16v/10uf")
> > > System.err.println(cql);
> > >
> > > where
> > > String getCQL(String cf, String path) {
> > > MessageDigest md = MessageDigest.getInstance("SHA1");
> > > String rowID = Base64.encode(md.finish(path.getBytes("UTF-8")));
> > > return "select * from "+cf+" where rowid = '"+rowID+"'";
> > > }
> > >
> > > yields
> > >
> > > select * from pictures where rowid = 'NzdlZmU4OTZmNGM4MzMwYzZ'
> > >
> > > If you want to find the parent then
> > >
> > > mapOfCassandraMappers.get("catalogue").getCQL("catalogue", "
> > > capacitors/electrolytic/axial/16v")
> > >
> > > select * from pictures where rowid = 'ZGFzZGZzZnNkYWZzYWRmc2R'
> > >
> > > And if the parent is stored in the property parent then
> > >
> > > select * from pictures where parent = 'ZGFzZGZzZnNkYWZzYWRmc2R'
> > >
> > > will generate a list of children. (Not sure about performance)
> > >
> > >
> > > Example 3:
> > > User is allowed to enter the RowID directly (identical to Example 1
> > > URL
> > >
> > >
> >
> /content/cassandra/cannesfilmfestival/TomCruiseCassino-20130402112345-ieb.jpg
> > >
> > > where
> > > String getCQL(String cf, String path) {
> > > return "select * from "+cf+" where rowid = '"+path+"'";
> > > }
> > >
> > > yields:
> > > select * from pictures where rowid = '
> > > TomCruiseCassino-20130402112345-ieb.jpg'
> > >
> >
> > This should be corrected as
> > select * from cannesfilmfestival where rowid = '
> > TomCruiseCassino-20130402112345-ieb.jpg'
> >
> >
> > >
> > >
> > > Does that make sense ?
> > >
> >
>
> Hi
>
>
> > Hi Ian,
> > I was in fact practicing some cql stuff in related to this response (with
> > cassandra cql terminal). This is quite a wonderful explanation for a new
> > comer like me. Thank you very much for the explanation again. Now it
> really
> > makes sense.
> >
>
> excellent!
>
>
> >
> > Other than the zero depth approach, I believe users will be more
> > comfortable with Example 2 approach.
> > Shall we go ahead with it ?
> >
>
>
> Yes, go for it. It will be interesting to see how hard it is to implement
> and how well (or not) it works. Remember, keep it as simple as possible and
> dont try and and cover every use case at the expense of getting a PoC
> working.
>
+1.
>
> However, dont forget, Unit tests mocked with Mockito are a quicker way of
> getting to working code, than no unit test coverage.
>
> Best Regards
> Ian
>
>
>
>
> >
> >
> > > Ian
> > >
> > >
> > >
> > >
> > > On 25 June 2013 05:29, Dishara Wijewardana <ddwijeward...@gmail.com>
> > > wrote:
> > >
> > > > On Mon, Jun 24, 2013 at 4:02 AM, Ian Boston <i...@tfd.co.uk> wrote:
> > > >
> > > > > Hi Dishara,
> > > > > Yes. 1 resource == 1 row.
> > > > > The columns within that row represent the properties of the
> resource.
> > > > > I suggest that you use standard property names where appropriate
> (eg
> > > > > sling:resourceType is the Resource.resourceType etc)
> > > > >
> > > > > The Resource itself should be adaptable to a generic
> > CassandraResource
> > > > > (which will probably implement Resource) which will have a map of
> > > > > properties containing all the columns of the cassandra row.
> (optimise
> > > > > later) A CassandraResource might look and feel like a Map<String,
> > > Object>
> > > > > or it might have a Map<String, Object> getProperties() method, or
> > > better
> > > > > still be adaptable to a Map. The essential think is dont hard code
> > the
> > > > > property names in the interface of CassandraResource for the
> moment.
> > ie
> > > > no
> > > > > getContentType() and no getMimeType(), as we dont really know what
> a
> > > > > CassandraResource will store.
> > > > >
> > > > > ResourceMetadata should be built from a subset of the
> > CassandraResource
> > > > > properties.
> > > > >
> > > > > You won't need to implement a ResourceResolver, only a
> > ResourceProvider
> > > > > (and Factory). I would use CQL in preference to other API methods.
> > > > >
> > > > > There is one thing that hasnt been mentioned, and thats the URL ->
> > > > > Cassandra Row mapping.
> > > > > There are several ways of doing this.
> > > > >
> > > > > eg:
> > > > > URL = /content/cassandra/<columnFamily>/<rowID>
> > > > > Cassandra Column Family = columnFamily
> > > > > Cassandra RowID = rowID
> > > > > or
> > > > > URL =
> /content/cassandra/<columnFamilySelector>/remainder/of/the/path
> > > > > Cassandra Cassandra Column Family =
> > > > > mapOfColumnFamilies.get(columnFamilySelector)
> > > > > Cassandra RowID = function(/remainder/of/the/path)
> > > > >
> > > > > or to take that one stage further
> > > > >
> > > > > public interface CassandraMapper {
> > > > > String getCQL(String columnFamilySelector, String path);
> > > > > }
> > > > >
> > > > Hi Ian
> > > > Thank you for the detailed explanation.
> > > >
> > > > OK. +1 for this approach with the mentioned flexibility.But I need a
> > > small
> > > > clarification. With this approach,
> > > >
> > > > URL = /content/cassandra/<columnFamilySelector>ROW-ID
> > > > ROW-ID - function(/remainder/of/the/path).
> > > > So you mean ROW-ID is something we have to programatically uniquely
> > > create
> > > > right ? like a UUID.
> > > >
> > > > What is this "/remainder/of/the/path" means ? Can you give an example
> > > with
> > > > real values in the context of a user who want to obtain a resource
> from
> > > > cassandra.
> > > > This is just for my understanding.
> > > >
> > > >
> > > >
> > > > >
> > > > > URL = /content/cassandra/<columnFamilySelector>/<remainderOfPath>
> > > > >
> > > > > String cqlQuery =
> > > > >
> > > > >
> > > >
> > >
> >
> mapOfCassandraMappers.get(columnFamilySelector).getCQL(columnFamilySelector,
> > > > > remainderOfPath);
> > > > >
> > > > > Which would allow us provided one or more implementations of
> > > > > CassandraMapper to map between URL and CQL.
> > > > >
> > > > >
> > > > > HTH
> > > > > Ian
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > On 23 June 2013 19:29, Dishara Wijewardana <
> ddwijeward...@gmail.com>
> > > > > wrote:
> > > > >
> > > > > > Hi Ian,
> > > > > >
> > > > > > What is the data mapping should be between Cassandra and Sling
> > > > resource.
> > > > > I
> > > > > > mean is a Sling Resource maps to a Cassandra Column ? Or Column
> > > Family
> > > > ?
> > > > > >
> > > > > > Because to get this Cassandra and Sling story correct we need to
> > > > finalize
> > > > > > this.
> > > > > > For an example what we eventually returns is a Sling resource.
> > > > Everything
> > > > > > that needs to fill in to create Sling resource should be stored
> in
> > > > > > Cassandra.
> > > > > > In a Sling resource,
> > > > > >
> > > > > > - Path - direct sling resource path
> > > > > > - ResourceType - nt:cassandra
> > > > > > - ResourceSuperType - ?
> > > > > > - ResourceMetadata - we can create this on the fly with the
> data
> > > > from
> > > > > > the corresponding column. At insertion, those need to be
> stored.
> > > > > > Following
> > > > > > are the ones which I thought might be useful by default to be
> > set
> > > > for
> > > > > > any
> > > > > > node. Please add if we need anything more.
> > > > > > - ContentType
> > > > > > - ContentLength
> > > > > > - CreationTime
> > > > > > - ModificationTime
> > > > > > - ResourceResolver - Do we need a resolver in this case ?
> > > > > >
> > > > > >
> > > > > > So I believe in CQL context, one ROW should represent a Sling
> > > > resource.
> > > > > If
> > > > > > that is the case for ResourceMetadata we might need a separate
> > column
> > > > to
> > > > > > store it since it has multiple values. I am not sure whether we
> can
> > > do
> > > > it
> > > > > > with CQL, but it should be possible with hector APIs may be.
> > > > > >
> > > > > > Appreciate your thoughts ?
> > > > > >
> > > > > >
> > > > > > On Wed, Jun 19, 2013 at 1:19 AM, Dishara Wijewardana <
> > > > > > ddwijeward...@gmail.com> wrote:
> > > > > >
> > > > > > > Hi Ian,
> > > > > > > I am starting this thread to keep track on things related to
> the
> > > GSoC
> > > > > > > project related milestone status updates and related
> discussions.
> > > > > > > So the first task over view will be as follows as per GSoC
> > proposal
> > > > > > > provided.
> > > > > > >
> > > > > > > 1. Implementing a CassandraResourceProvider to READ from
> > > Cassandra.
> > > > > > > Implementation Details [1]
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > [1] : Implementation Details:
> > > > > > >
> > > > > > > 1.A) Write a CassanrdaResourceProviderUtil which is
> basically a
> > > > > > > cassendra client which will facilitate all cassandra related
> > > > operations
> > > > > > > required by other modules (CassandraResourceProvider and
> > > > > > > CassandraResourceResolver).
> > > > > > >
> > > > > > > 1.B) Implementation of CassandraResourceProvider
> > > > > > >
> > > > > > > 1.C) Implementation of CassandraResourceResolver
> > > > > > >
> > > > > > > 1.D) Implementation of CassandraResource
> > > > > > >
> > > > > > >
> > > > > > > And I will start writing the CassanrdaResourceProviderUtil
> class
> > > > which
> > > > > > > will do basic add and get using hector API. Please provide any
> > > > feedback
> > > > > > > that will be useful to accomplish this task.
> > > > > > > So for this how does path mapping should be done. Because for
> > > > example,
> > > > > > the
> > > > > > > path of the cassendra node will not be same as the jcr node
> path.
> > > i.e
> > > > > > > provider will ask a node path /system/myapps/test/foo and where
> > > > should
> > > > > we
> > > > > > > return it from Cassandra. Aren't we have to first consider the
> > > WRITE
> > > > > > aspect
> > > > > > > to Cassandra ?
> > > > > > >
> > > > > > >
> > > > > > > --
> > > > > > > Thanks
> > > > > > > /Dishara
> > > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Thanks
> > > > > > /Dishara
> > > > > >
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > Thanks
> > > > /Dishara
> > > >
> > >
> >
> >
> >
> > --
> > Thanks
> > /Dishara
> >
>
--
Thanks
/Dishara
