#CSUC14

1. Web Services:
Encapsulation, Reusability, and
Simplicity
#CSUC14
Presented by
Wing Ming Chan, September 16, 2014
Upstate Medical University
chanw@upstate.edu
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2. Topics
 Encapsulation: data and data manipulation
hiding
 Usernames and passwords
 Creating phantom entities in Cascade
 Fully qualified identifiers
 Reusability: code ready to use without
modification
 AssetOperationHandlerService
 Asset and Property classes
 Simplicity: lines of code
 Cascade and AssetTree classes
 CascadeInstances and Report classes 2

3. Part 0: Three Questions
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4. Purposes
 Look for positive answers
 Reveal the problems
 Highlight the main issues
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5. Question 1
 How many of you can write a web service
program, doing something, anything, without
hard-coding the username and password
anywhere in your code?
 Main concern
 Security and encapsulation of sensitive data
 Access restrictions
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6. Question 2
 How many of you can work with the first node of
the second multiple field in a data definition
block, without looking at the read dump of the
block? Can you hard-code the location of the node
in you program?
 Main concern
 Encapsulation and reusability 6

7. Locating Nodes
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8. Question 3
 Besides the use of require_once or
include_once, how many of you can use a
single semi-colon in your code to do the following:
 Associate metadata set 1 with all folders in a site
(including Base Folder)
 Associate metadata set 2 with all files in the site
 Associate metadata set 3 with all symlinks in the site
 Requirements: no program-specific data allowed
in the required/included files; all information
related to metadata sets, folders, files, and
symlinks must show up in your code
 Main concerns
 Reusability and simplicity
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9. Part 1: Encapsulation
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10. The Typical Way of
Starting a Program
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11. Problems?
 Programs are tied with usernames, passwords,
and WSDL URL’s
 People can come and go
 Changes of passwords
 URL’s can change too (different instances)
 Passwords exposed
 Security
 A single program used by multiple users
 Usernames and passwords change depending on the
users using the same program
 Access restrictions
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12. Phantom: Episode I
 Detachment of structuredData from
dataDefinition in web services
 Created by web services
 Only affects data definition blocks (including those
plugged into pages)
 Can be created in pages, but haven’t figure out a way
to reveal the hidden content
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13. Data Definitions
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14. Data Definition Blocks
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15. REPLACING STRUCTUREDDATA
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16. Results
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17. Hidden Multiple Nodes
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18. Results
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19. The Other Side of the Same Coin I
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20. The Other Side of the Same Coin II
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21. Creating a Java Error
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22. A NIGHTMARE…
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 Pretend that I am you enemy
 What I can do to you:
 Detachment of data definitions from content types
 Assigning an empty string to a checkbox in data
definition blocks
 Data definition manipulation with phantom nodes
 How long will it take to solve the problem: Days?
Weeks?

23. Encapsulating Usernames and
Passwords: a Two-Step Approach
 Step 1: move usernames and passwords out of
programs to authentication files
 Step 2: hide usernames and passwords from the
system altogether
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24. Moving Usernames and Passwords
Out of Programs:
Using Authentication Files
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25. Authentication File Example
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26. Password-Protected Page
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27. Using Session
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28. Using Command-Prompt Arguments
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29. Authentication File:
Entry Point to Code Library
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30. The AssetOperationHandlerService
Class: Encapsulating Operations
 Encapsulation
 Username and password
 URL
 The SoapClient object and all operations
 All parameters required for operations
 The instance $service:
 Instantiated in the authentication files
 Passed from client code to code library
 Performs all basic operations in code library
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31. Fully Qualified Identifiers
 When working with data definition blocks or
pages, we need to work with nodes
 A fully qualified identifier of a node is the full
path of the node, including all the information
about ancestors and absolute position
 Example: pie;1;pie-is-sliced
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32. What Is Special About
Fully Qualified Identifiers
 Example: pie;1;pie-is-sliced
 The ;1 part following an identifier indicates that
the field is a multiple field
 ;0 means that the node bearing this identifier is
the first node in the set; ;1 means that the node
is the second node of the set
 Unlike array indexes, the fully qualified
identifier of a node never changes, no matter how
many cousins and siblings it has
 A more complicated example: main-field;
group;2;sub-group;1;text;3
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33. Why Fully Qualified Identifiers?
 They never change: can be hard-coded in
programs
 Easy node look-up
 Possible to use for and foreach loops
 Encapsulation of arrays and stdClass objects
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34. DATADEFINITIONBLOCK::GETIDENTIF
IERS
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35. Part 2: Reusability
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36. Why OOP?
 Encapsulation
 Hiding complicated program logic
 Hiding data and raw data structures
 Reusability
 The entire library consists of reusable code
 Easy object retrieval
 Providing look-up mechanism
 Setting and editing data and metadata, and
preventing unacceptable input
 Error checking and exception handling
 Inheritance
 Problems with web services 36

37. Problems with Web Services I
 It is possible to delete the value of a required
field using web services (e.g. in a metadata set)
 Cascade won’t complain when an unacceptable
boolean value is assigned to a field (e.g. fals
instead of false)
 An unacceptable boolean value is ignored
 Unlike dateTime (which is represented by an object)
 Cascade won’t complain when an unacceptable
string value is assigned to a dropdown
 An undefined item is introduced
 An empty string will also work
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38. Problems with Web Services II
 When a single-item checkbox is assigned an
empty string, Cascade won’t complain
 However, the associated data definition block
cannot be viewed (a Java error)
 The field should have been assigned the string
‘::CONTENT-XML-CHECKBOX::’ instead
 Phantoms we have met
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39. Problems with Web Services III
 Assignment of NULL vs. unset
When modifying temporal settings for scheduled
publishing (for a site, a publish set, or a destination),
assignments of the NULL value to properties won’t
work
 Instead, we must unset the properties
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40. ASSET AND PROPERTY
 Asset: an abstract class
 Other abstract subclasses: ContainedAsset,
Container, Block, Format, etc.
 42 concrete classes corresponding to 42 asset
types defined in the WSDL
 All methods have returned values
Method chaining possible
 stdClass objects within an asset are
represented by subclasses of Property
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41. Inheritance
 Reusability
 An asset class can be reused to deal with any assets
of the same type
Metadata-related classes can be reused in File,
Page, Block (and its subclasses), Format (and its
subclasses) and Symlink
Members in a parent class inherited by child classes,
avoiding repetition of code
 Separate code files
 Less code per file
 Easier to maintain
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42. Exception Handling
 All classes throw exceptions of various types
 Client code is expected to deal with exceptions
 Two modes of execution: strict and lenient
 To throw or not to throw? Cascade::getAsset
vs. Cascade::getX (e.g. Cascade::getPage)
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43. Part 3: Simplicity
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44. Writing Client Code
 Client code does not look like ‘normal’ Cascade
web service code
 No username and password
 No arrays of raw data or stdClass objects
 Chained method calls
 Handling of exceptions
 A lot shorter: simplicity!
 Normally, no use of new keyword
 Easy retrieval of asset objects
 Easy retrieval of associated objects of pages
 High level classes: Cascade and AssetTree 44

45. Retrieving an Asset Object
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46. Dumping an Asset Object
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47. Working With
A Data Definition Block
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48. Displaying Page-Related Information
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49. Setting Access Rights
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50. Setting Content Type
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51. Switch Content Type
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52. ASSETTREE
 A tree structure consisting of:
 Root container
 Children
 Sub-trees
 What it is good for:
 Creating reports
 Modifying assets of a certain type or types
 The AssetTree::traverse method
 Visits the root, every children of the root, and recursively all
sub-trees (depth-first traversal)
 Accepts global functions, parameters, and results array
(passed in by reference)
 Global functions as filters 52

53. ASSETTREE::TRAVERSE
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54. ASSETTREE::APPLYFUNCTIONSTOCHIL
D
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55. MetadataSet Associations
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56. Global Function Used
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57. Publishing Every Page in a Folder
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58. AssetTree Recipes
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59. Phantom: Episode II
 Detachment of structuredData from
dataDefinition in web services
 Created by changes of data definitions
 Affects web services only
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60. CascadeInstances:
The Ultimate Test for Simplicity
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61. REPORT:
ENCAPSULATING ASSETTREE
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62. Questions?
 Tutorial: http://www.upstate.edu/cascade-admin/
projects/web-services/
 Email: chanw@upstate.edu
 A web service user group?
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