CMIS

About 6 moths ago I was complaining about CMIS that it considers all requests which contain the same credentials (i.e. login and password are the same for all requests) as requests from the same client, and for all requests containing the same credentials CMIS uses the only one repository session, unfortunately we didn’t implement solution proposed in that blogpost – it is hard to maintain different passwords across clients, meanwhile we have started receiving concurrency-related errors, so, it was required to undertake something and I have found a solution – it is enough to replace just two classes in CMIS:

JMS high availability feature. Part II

Why I did recall a feature, which I have never used before and will never use in the future? The explanation is following: In order to refresh my memory I was reading installation guide for Content Server 7.3 and noticed following statement:

Actually, documentation does not explain what does mean “methods requiring trusted authentication”, it seems that remote JMS supports workflow methods only, but from any perspective this statement sounds weird, the problem is on that moment I already discovered vulnerability in Content Server which allows attacker to download $DOCUMENTUM_SHARED/config/dfc.keystore file, this file is very interesting because it allows to connect to Content Server as superuser (note the value of server_trust_priv flag):

[dmadmin@docu72dev01 config]$ keytool -list -v -keystore dfc.keystore 
Enter keystore password:  

*****************  WARNING WARNING WARNING  *****************
* The integrity of the information stored in your keystore  *
* has NOT been verified!  In order to verify its integrity, *
* you must provide your keystore password.                  *
*****************  WARNING WARNING WARNING  *****************

Keystore type: JKS
Keystore provider: SUN

Your keystore contains 1 entry

Alias name: dfc
Creation date: May 5, 2015
Entry type: PrivateKeyEntry
Certificate chain length: 1
Certificate[1]:
Owner: CN=dfc_zOkF5qKyACcQUjLJD2bt1y3dXr0a, O=EMC, OU=Documentum
Issuer: CN=dfc_zOkF5qKyACcQUjLJD2bt1y3dXr0a, O=EMC, OU=Documentum
Serial number: 4d23be10ce8e183732c451091e0e3dbf
Valid from: Tue May 05 16:03:10 MSK 2015 until: Fri May 02 16:08:10 MSK 2025
Certificate fingerprints:
         MD5:  8B:BD:5C:F6:18:9D:27:9F:28:A7:69:A4:45:AD:32:63
         SHA1: 37:CC:14:C7:3E:BA:8F:AF:CE:E8:E5:4E:D2:F5:01:AF:3E:B6:1D:3F
         SHA256: 88:FA:7A:04:F8:47:AE:88:AC:EB:D5:BE:28:80:A6:7E:21:51:34:86:A5:96:0E:FF:11:61:90:E9:EA:AC:B4:0C
         Signature algorithm name: SHA1withRSA
         Version: 1


*******************************************
*******************************************


API> retrieve,c,dm_client_rights where client_id='dfc_zOkF5qKyACcQUjLJD2bt1y3dXr0a'
...
08024be980000587
API> dump,c,l
...
USER ATTRIBUTES

  object_name                     : dfc_docu72dev01_3dXr0a
  title                           :
  subject                         :
  authors                       []: <none>
  keywords                      []: <none>
  resolution_label                :
  owner_name                      : dmadmin
  owner_permit                    : 7
  group_name                      : docu
  group_permit                    : 1
  world_permit                    : 1
  log_entry                       :
  acl_domain                      : dmadmin
  acl_name                        : dm_45024be980000222
  language_code                   :
  client_id                       : dfc_zOkF5qKyACcQUjLJD2bt1y3dXr0a
  public_key_identifier           : 5F6CF69241D4745C01C943BAD1AFFB027398EF32
  host_name                       : docu72dev01
  allowed_roles                 []: <none>
  allow_all_roles                 : T
  allow_all_priv_modules          : F
  principal_auth_priv             : T
  server_trust_priv               : T
  app_name                        :
  is_globally_managed             : F

So, there is a kind of interesting situation: official software is unable to take advantage of trusted authentication, but attacker can 🙂

But on the last week EMC published another interesting support note – JMS high availability feature does not work:

dfc.query.should_include_object_name

Have never thought that my colleagues may teach me something…

Yesterday I asked my colleague, who is trying to improve his skills in performance optimisation, whether he had any idea how to improve this SQL statement:

SELECT ALL dm_folder.r_object_id
  FROM dm_folder_sp dm_folder
 WHERE     (    EXISTS
                   (SELECT r_object_id
                      FROM dm_folder_r
                     WHERE     dm_folder.r_object_id = r_object_id
                           AND r_folder_path = :"SYS_B_00")
            AND (dm_folder.object_name = :"SYS_B_01"))
       AND (    dm_folder.i_has_folder = :"SYS_B_02"
            AND dm_folder.i_is_deleted = :"SYS_B_03")

and, surprisingly, the answer was: “Yes, I have seen something similar on support site – EMC suggest to set dfc.query.should_include_object_name and dfc.query.should_include_object_name properties, something like:

dfc.query.object_name_for_docbase[0]=<docbase_name>
dfc.query.should_include_object_name[0]=false


Well, as was expected both dfc.query.should_include_object_name and dfc.query.should_include_object_name properties are not documented, so let discuss the problem more thoroughly.

Imagine that we are maintaining following folder structure in our docbase:

\_CLIENT_1
  \_CLAIMS
  \_INVOCES
\_CLINET_2
  \_CLAIMS
  \_INVOCES
...
\_CLIENT_X
  \_CLAIMS
  \_INVOCES

i.e. for every client we create the same folder structure and when we want to store invoice for particular client we do something like:

create,c,dm_document
set,c,l,object_name
xxx
link,c,/CLIENTS/CLINET_1/INVOICES
save,c,l

the problem is that upon link call DFC calls IDfSession#getFolderByPath method to retrieve folder object with particular path, and inside IDfSession#getFolderByPath method DFC does following: it cuts off object name part from the path (i.e. everything after last ‘/’) and builds following DQL query:

SELECT r_object_id FROM dm_folder 
WHERE object_name='INVOICES' 
 AND ANY r_folder_path='/CLIENTS/CLINET_1/INVOICES'

such implementation is bit weird for two reasons:

  • when I do the same I just write something like “retrieve,c,dm_folder where any r_folder_path=”…” and do not bother myself about object name
  • Content Server has a build-in FolderIdFindByPath RPC command:
    API> apply,c,,FolderIdFindByPath,_FOLDER_PATH_,S,/dmadmin
    ...
    q0
    API> next,c,q0
    ...
    OK
    API> get,c,q0,result
    ...
    0c01d92080000105
    API> close,c,q0
    ...
    OK

    which generates following effective SQL statement:

    select r_object_id from dm_folder_r where r_folder_path = :p0

so, I have no idea why DFC performs extra logic here, moreover, in case of current DFC implementation we are getting overcomplicated SQL query and, sometimes database engine fails to build a good execution plan for this query (this is caused by dumb recommendation to set CURSOR_SHARING database parameter to FORCE and depending on docbase structure execution of such query may take minutes). Below are two possible execution plans for this query:

good (dm_folder_r is a leading table – querying dm_folder_r table by r_folder_path will always return not more than one row):

and bad (dm_folder_r is not a leading table – imagine that we have 1 million clients and hence 1 million INVOICE folders, so querying dm_sysobjec_s table by object_name first will return 1 million records):

in case of “retrieve,c,dm_folder where any r_folder_path=”…” execution plan is always good:

In 2011 (if my memory serves me right), I solved such performance problem by marking index on dm_folder_r(r_folder_path) as unique – in this case database engine always builds the correct execution plan because it knows that querying dm_folder_r table will always return not more than one row, however in recent versions DFC it is possible to disable it’s dumb behaviour by setting dfc.query.should_include_object_name and dfc.query.should_include_object_name properties – can’t understand why this wasn’t enabled by default.

OpenText rep promised further stagnation of Documentum

Pro Documentum

Check comments for Maybe OpenText will add value to Documentum after all:

Well,

Erik van Voorden: Nothing will change for documentum users. They will still get that same level of support as under EMC. Only the company name has changed.

how to treat such statements from a person, who have never worked before in ECM industry and doesn’t have great employment history? I would say: sometimes, it is better to keep silent, and in case of Documentum and OpenText there are a plenty of reasons to do that – take a look how it is possible to turn single phrase into blogpost.

At first, EMC support was always poor (I would rate it as 2 out of 5), moreover, after 2013 it became inadequate (1 out of 5), claiming that you are going to keep support on the same level is a worst advertisement ever –

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