Oracle Apex internals: template, source, conditional SQL storage

Abstract

While working with Apex I was building, backing up, customizing applications. I also had a few custom themes, theme-rebuilds. Now I need to update interfaces for 22 applications. Update includes custom CSS, JS'es, styles and HTML customizations for regions, region sources, templates, items, buttons. My applications contain hundreds of regions and items, its time to start digging Apex internals. Some of them can be found documented in forums, some of them I was not able to locate.

Warning

Any mistype or abuse may damage Apex IDE, usability, upgradability and your own application sources. Consider yourself warned.

General remarks

Flow_id - Apex application ID, consider always including in your query or at least limiting to a range below 4000.
Flow_step_id - application page ID.
Make database and application backups. At least copy some stuff to comments column.
If you have at least a couple applications most of the columns are self explanatory and follow same naming notation across all Apex tables.

Main Apex tables and their purpose

Apex schemas are named HTMLDB or APEX with trailing version number (examples: HTMLDB_020000, APEX_030200, APEX_040100, APEX_050000, dont recall if WEBDB had its own naming pattern). Tables are mainly starting with WWV_(FLOW) prefix.

WWV_FLOW_STEP_ITEMS - page items (like P101_USERNAME), I mainly use this table for mass item template changes (ITEM_FIELD_TEMPLATE), label alignment change (LABEL_ALIGNMENT), some very specific template changes (I use simple items to display clickable icons). My personally favorite field is TAG_ATTRIBUTES - custom HTML, CSS, Javascript code input.

WWV_FLOW_REGION_REPORT_COLUMN - report-type region column description and customization. I mainly use report columns for links with icons (COLUMN_LINKTEXT), other uses may include massive label or value alignment changes.

WWV_FLOW_ROW_TEMPLATES - report templates (not regions), I use them for massive HTML/CSS changes, class updates. Almost every column in this table is obvious and usable.

WWV_FLOW_STEP_BUTTONS - page buttons (obviously). I mainly use this table when I change button template (remember that application template ID's are different - I change one item in Apex, then update the rest based on changes in table). Column BUTTON_IMAGE. Can also be used for massive button alignment, condition or image changes.

WWV_FLOW_PAGE_PLUGS - hardest one to find or come up with, but also one of the most important ones - Region definition and sources. I do have some conditional SQL which displays certain icons (URL from webserver storage), I use PLUG_SOURCE column for mass updates when changing design templates. Can be used for condition, template or title changes.

WWV_FLOW_WORKSHEET_COLUMNS - this one may also be tricky to locate - interactive report region column desciptions. I mainly use this table for icon/image changes, mass link or interactive report column alignment changes.

Drupal performance improvement (valid for version 7)

Abstract

Drupal version 7, objective is to improve both Desktop and mobile versions of your website, improve SEO ratings like page loading speed, text to HTML ratio, number of CSS files, Javascript footprint size, overall page footprint size, number of files to load.

Improvement process

Drupal is module based CMS, so you are going to need only a couple of modules added to your installation. Each module and its use follows. Hopefully this article will be updated quite a few times.

PHP filter + Browscap

There are a couple of Drupal modules that allow hiding content based on device size (mobile or desktop). Tried quite a few Mobility modules, but none of them seem to work, where old or required modules like Cache to be turned off. And its not what I wanted.

In mobile versions I sometimes disable large slideshow blocks or page images, if you are up for that, here is what you do: download browscap, deploy it and enable both modules (PHP filter is native Drupal module). Open you block, enable PHP condition and paste this snippet:

<?php 
$mobile_agent = browscap_get_browser() ;
if($mobile_agent['ismobiledevice'] == "false"){return true;} 
?> 

Minify

This module simply removes all the unnecessary characters from your HTML and Javascript files. Compresses and creates copies of all you Javascript includes. This makes your files download faster. Some of the files are not being compressed due to their already small footprint, pay no attention to them. I will not describe how to use this module, its self explanatory. Once deployed you will find it under cache/performance management. Link for download. Suggesting enabling it when production ready since output HTML and JS files are hardly human readable.

Advagg

Full module name is Advanced CSS/JS Aggregation. This module combines (even cached) css files into a single file, which gives quite a few performance points in some of SEO evaluation tools. Combining your CSS files also reduces text/html ratio. Setup has quite a few tabs, but just follow the setup and enable CSS compression.

Summary

Usage of all these modules above may improve your website SEO evaluation by up to 10%. If not, then they will at least improve your page loading speed and overall performance compared to your competitors. Any feedback to this article is highly appreciated.

Oracle Apex Textarea printing with line breaks

Objective

Use Text Fields or Text Area fields for text input to build a document template generator. Oracle Apex version 4.

Problem(s)

With version 4 Apex introduced quite a few variable session handling changes, if you had a long experience with V3 - you will be stuck quite a few times. When you enter text in Rich Text editor or Text Area field and later try to print it in HTML area - either all HTML tags are exposed or removed. In the end you get plain text with different level of garbage. In V3 you could solve this by copying text to a simple Display Only item and use it hidden, then all the HTML tags could be prevented. Here are the three Text Areas used. Text with simple line breaks () or paragraph breaks (+) - which are invisible in UI of Text Area. 

Solution


In HTML area add <pre> and </pre> tags for the Text Area fields. Same tag applies if you change your item to read-only on display. Print preview looks great.

ImageMagick and ghostscript delegate problem: sh gs command not found

PROBLEM

Recent ImageMagick update kicked a little in the nuts. I mainly convert PDF to PNG and then use them for OCR. Here is how it welcomed me after an update to 6.7.2:

sh: gs: command not found
convert: missing an image filename

It works ok from a command line, but fails from Java or any external environments. At first the error may look like a command line syntax change, but it isnt, dont start moving your flags places or in-front/after PDF file - this is not the problem here.

SOLUTION

1) # which gs
2) locate delegates.xml file in your system
3) open the file for editing (# nano /etc/ImageMagick/delegates.xml)
4) find all occurrences of "gs", which will be simply put in html quotes:  <...>command=""gs" -q <..> and replace it with the output of you "which gs" result, in my case it looked like this: <..>command=""/usr/local/bin/gs" -q <..>. Leave the surrounding syntax intact.

After that just save the file and run you external command again. There will be around 10 occurrences, replace them all to be on the safe side, I suspect that its only PS configurations that had to be changed.

SSL certificate hash transition from SHA1 to SHA2. ORA-28857

Abstract

The SHA-1 cryptographic hash algorithm has been known to be considerably weaker than it was designed to be since at least 2005. As part of their SHA-2 migration plan, Google, Microsoft and Mozilla have announced that they will stop trusting SHA-1 SSL certificates. Google will begin phasing out trust in SHA-1 certificates by the end of 2014, while Microsoft and Mozilla will begin phasing out trust for SHA-1 certificates in 2016.

Problem(s)

If you are using Google Chrome - some https websites or services using SHA1 will not be opened and you will likely get an error displayed in article image. Another situation that you may bump into is Oracle Wallet. Looks like Oracle up to 11.2.0.2 doesn’t support SHA-2 based certificates. If you have a 10.x wallet and website changed its certificate to SHA2 - you will not be able to import it - you will get an error "some trusted certificates could not be installed". See image attached.
Also when connecting to such a site using UTL_HTTP.REQUEST you will end up with an ORA error: "Request Failed: ORA-28857: Unknown SSL error".

Suggestions

Upgrade Java, Tomcat and Oracle.

Dates to remember

November 2014 - SHA-1 SSL Certificates expiring any time in 2017 will show a warning in Chrome 39.
December 2014 - SHA-1 SSL Certificates expiring after May 31, 2016 will show a warning in Chrome 40.
January 2015 - SHA-1 SSL Certificates expiring any time in 2016 will show a warning in Chrome 41.
January 1, 2016 - Microsoft ceases to trust Code Signing Certificates that use SHA-1.
January 1, 2017 - Mozilla Firefox and Microsoft ceases to trust SSL Certificates that use SHA-1.

Services currently supporting SHA2

Apache server 2.0.63+ with OpenSSL 0.9.8o+
Java based servers using Java 1.4.2+
OpenSSL based servers using OpenSSL 0.9.8o+
Oracle Wallet Manager 11.2.0.1+
Oracle Weblogic 10.3.1+

Larry Ellison on self

“When you write a program for Android, you use the Oracle Java tools for everything, and at the very end you push a button and say, ‘Convert this to Android format.'” - Larry Ellison, 2013, CBS interview.

Oracle 10g on Centos 6.7 - x86 issues: ntcontab.o, snmccolm.o, ORA-27125

Abstract

Its getting harder and harder to install good old 10g on newer Centos versions. Last attempt on 6.5 was semi-problematic, with some extra packages missing, 6.7 deployment was even more challenging.

System specifications

Centos version (/etc/issue): CentOS release 6.7 (Final)
Oracle version: Version 10.2.0.1.0 Production (10201_database_linux_x86_64.cpio)

Problems and solutions

#1: Error invoking target 'ntcontab.o' of makefile

This error occurred around 65% in installation progress, aborting is not an option - more errors will follow and in the end whole process fails. Did some testing and it appears that one process is building the file, next one is instantly deleting it:

# cp /misc/oracle/product/10.2.0/db_1/lib32/ntcontab.o /misc/oracle/product/10.2.0/db_1/lib/

But in the end it looks like it was one of the following (where not needed in 6.5):

# yum install libaio-devel.i686 -y
# yum install zlib-devel.i686 -y
# yum install glibc-devel -y
# yum install glibc-devel.i686 -y
# yum install libaio-devel -y
# yum install ksh -y
# yum install glibc-headers

#2: /misc/oracle/database/product/10.2.0/db_1/sysman/lib/snmccolm.o: could not read symbols: File in wrong format

It might be that it may be solved with some more x86 packages thrown into the pile, I was not able to find the exact culprit. Many of the sources online simply telling to ignore this and fix it with 10.2.0.4 patch. Thats what we'll do: Ignore.

#3: ORA-27125: unable to create shared memory segment

Reason is unknown, it was thrown by DBCA with continuous installation process.
The solution is very simple, first check the oracle user group information:

[oracle@storage] $ id oracle 
uid = 500 (oracle) gid = 502 (oinstall) groups = 502 (oinstall), 501 (dba) 
[oracle@storage] $ more /proc/sys/vm/hugetlb_shm_group 
0 

Execute the following command as root, the dba group is added to the system kernel:

[oracle@storage] $ echo 501 > /proc/sys/vm/hugetlb_shm_group

Continue with DBCA, step will fail, but then retry DBCA, the problem disappeared and database was created.

#4: bonus problem, not Centos 6.7 related: You do not have enough free disk space to create the database

My bad was that I had 12TB storage mounted, looks like I missed the 10g storage requirement: 400MB, but less then 2TB. Found no other solution then to unmount /dev/sdb1, shrink it with gparted to get ~500GB space, ext4 it and mount the new device /dev/sdb2 to another mount point /oracle.

Conclusion

Move to 11i or 12c, its about time.