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 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.
Other than the zero depth approach, I believe users will be more
comfortable with Example 2 approach.
Shall we go ahead with it ?
> 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
