The document discusses multi-tenancy in Java applications, where a single application instance can serve multiple clients or tenants simultaneously. Isolating each tenant's data, customizations, and other information is challenging. Hibernate provides functionality for multi-tenancy configurations through annotations that specify tenant identifiers and data sources. Migrating to a multi-tenant architecture requires adjustments to caching, schema updates, and logging to properly attribute activities to tenants.

1. MULTI-TENANCY
in Java applications
@ladislavGazo
gazo@seges.sk

2. THE APPLICATION
user
|
bunch of JavaScript
|
service
|
domain model

3. IMPLICATION
user1 ... userN
|
same bunch of JavaScript
|
service
|
ONE database

4. ONE APPLICATION TO RULE THEM ALL
The term multi-tenancy in general is applied to software
development to indicate an architecture in which a single running
instance of an application simultaneously serves multiple clients
(tenants).
This is highly common in SaaS solutions.
Isolating information (data, customizations, etc) pertaining to the
various tenants is a particular challenge in these systems.

5. SPLIT ME NOW!
user1 -> BA, user2 -> BA, user 3 -> KE, user 4 -> ZA
|
again the same JavaScript
|
(almost) the same service
|
DB (BA), DB (KE), DB (ZA)

6. a lot of "tenant" dependent data - high volumes
performance
separation -> easier backup and restore
scalability of front-end and service layer

7. HIBERNATE IS THE EASIEST

8. MULTI-TENANT CONFIGURATION
<rprynm=hbraemlieac"vle"AAAE /
poet ae"ient.utTnny au=DTBS" >
<rprynm=hbraetnn_dniirrsle"vle"ksgshodlnecniuainMlieatdniireovr /
poet ae"ient.eatietfe_eovr au=s.ee.rdeei.ofgrto.utTnnIetfeRsle" >
<rprynm=hbraemlitnn_oncinpoie"vle"r.ient.evc.dccnetossi
poet ae"ient.ut_eatcneto_rvdr au=oghbraesriejb.oncin.p.
DtSucBsdutTnnCnetoPoieIp"/
aaoreaeMlieatoncinrvdrml >
<rprynm=hbraecneto.aaore vle"aacm/n/dch"/
poet ae"ient.oncindtsuc" au=jv:opevjb/r >
<rprynm=hbraemlitnn.aaoreietfe_o_n"vle"eal"/
poet ae"ient.ut_eatdtsuc.dniirfray au=dfut >

9. SWITCH IT ON
hbraemlieac
ient.utTnny

10. CONFIGURE WHERE TO LOOK FOR THE
CURRENT TENANT IDENTIFIER
hbraetnn_dniirrsle
ient.eatietfe_eovr

11. WHERE ARE MY CONNECTIONS?
hbraemlitnn_oncinpoie
ient.ut_eatcneto_rvdr
Hibernate's
DataSourceBasedMultiTenantConnectionProviderImpl
utilizes JNDI lookups

12. POINT TO JNDI ROOT FOR DATASOURCES
hbraecneto.aaore
ient.oncindtsuc

13. ... AND THE DEFAULT
hbraemlitnn.aaoreietfe_o_n
ient.ut_eatdtsuc.dniirfray
So in the end =
jv:opevjb/rdfut
aacm/n/dch/eal

14. BUT THERE ARE THINGS THAT DON'T WORK
EHCache configuration from previous version is different
Hibernate's internal schema update does not work
NPE !!! ........ who would have said that

15. MIGRATION

16. HIBERNATE EXPORTER
is not helpful

17. DO YOU HAVE ENVERS?
then you need custom exporter

18. IT IS EASY TO WRITE
but don't forget the AuditConfiguration
EbCniuainjaofgrto =nwEbCniuain)cniue
j3ofgrto pCniuain
e j3ofgrto(.ofgr(
uiNm,nl)
ntae ul;
Cniuainhbraeofgrto =jaofgrto
ofgrto ientCniuain
pCniuain
.eHbraeofgrto(;
gtientCniuain)
hbraeofgrto.ulMpig(;
ientCniuainbidapns)
Adtofgrto adtofgrto =Adtofgrto.eFr
uiCniuain uiCniuain
uiCniuaingto(
hbraeofgrto)
ientCniuain;
and use EnversSchemaGenerator at last

19. GET RID OF NPE BUG
{"ient.utTnny,
hbraemlieac"
"ient.eatietfe_eovr,
hbraetnn_dniirrsle"
"ient.ut_eatcneto_rvdr,
hbraemlitnn_oncinpoie"
"ient.oncindtsuc"
hbraecneto.aaore,
"ient.ut_eatdtsuc.dniirfray }
hbraemlitnn.aaoreietfe_o_n"

20. RUN THE EXPORTER FROM MAVEN

21. COMBINE IT WITH LIQUIBASE
version 3.0.6 contains feature to populate all tenant databases
Mlieatpigiubs
utTnnSrnLqiae

22. DON'T FORGET...
it is maintenable but generated SQL needs to be checked
existing databases must be moved to "point 0"

23. A BIT OF LOGGING
http://www.slf4j.org/faq.html#logging_performance
Importance of logging - using MDC to track requests
MCpt"eat,cinOg)
D.u(tnn" letrz;
lgjapne.totlyu.ovrinatr =AP[dIO61]-%5
o4.pedrsdu.aotCnesoPten
P %{S80}
-p
[t%{eat|Xrqetd]%:M%3.0{}-%%
%|Xtnn}%{eusI} F% -03c1
mn

24. AND THE MOST BORING...
DESIGN
your app to be multi-tenant

25. SEND TENANT IDENTIFICATION
in HTTP Header
use Filter to get it out
in Service parameters
using ThreadLocal variable
via tenant-URL-based service calls
rmi://localhost:12345/<tenant>/<service>
etc...

26. THANKS FOR LISTENING
@ladislavGazo
gazo@seges.sk