On 27 June 2013 02:34, Dishara Wijewardana <[email protected]> wrote:
> On Tue, Jun 25, 2013 at 4:52 AM, Ian Boston <[email protected]> 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. 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 <[email protected]> > > wrote: > > > > > On Mon, Jun 24, 2013 at 4:02 AM, Ian Boston <[email protected]> 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 <[email protected]> > > > > 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 < > > > > > [email protected]> 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 >
