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From "ASF GitHub Bot (Jira)" <j...@apache.org>
Subject [jira] [Commented] (QPID-8361) [Broker-J] Create a developer guide for Qpid Broker-J
Date Mon, 16 Sep 2019 13:39:01 GMT

    [ https://issues.apache.org/jira/browse/QPID-8361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16930553#comment-16930553
] 

ASF GitHub Bot commented on QPID-8361:
--------------------------------------

vavrtom commented on pull request #36: QPID-8361: [Broker-J] Create a developer guide for
Qpid Broker-J
URL: https://github.com/apache/qpid-broker-j/pull/36#discussion_r324157818
 
 

 ##########
 File path: doc/developer-guide/src/main/markdown/code-guide.md
 ##########
 @@ -0,0 +1,446 @@
+# Qpid Broker-J Coding Standards
+
+This article documents the standard adopted for Java code in the Qpid project.
+All committers are expected to follow this standard.
+
+## Executive Summary
+
+The main things for layout purposes in the standard are:
+
+ * Indent using four spaces. No tabs.
+ * braces always go on new lines, e.g.
+```java
+if (x == 5)
+{
+    System.out.println("Hello");
+}
+```
+
+rather than
+
+```java
+if (x == 5} {
+    System.out.println("Hello");
+}
+```
+
+Always add braces, e.g.
+
+```java
+    if (x == 5)
+    {
+        System.out.println("Hello");
+    }
+```
+rather than
+
+```java
+if (x == 5}
+    System.out.println("Hello");
+```
+
+Fields prefixed with underscores, e.g. `_messageCount`
+
+Spaces after keywords but no spaces either before or after parentheses in method calls, e.g.
+
+```java
+    if (x == 5)
+```
+
+rather than
+
+```java
+    if(x==5)
+```
+
+but
+
+```java
+    foo.bar(4, 5)
+```
+
+rather than
+
+```java
+    foo.bar( 4, 5 )
+```
+
+## Details
+
+### Introduction
+
+This document describes two types of coding standard:
+
+1. **Mandatory** standards must be followed at all times.
+2. **Recommended** standards should in general be followed but in particular cases may be
omitted
+   where the programmer feels that there is a good reason to do so.
+
+Code that does not adhere to mandatory standards will not pass the automated checks
+(or a code review if the guideline is not stylistic).
+
+### Source files
+
+This section defines the general rules associated with the contents of a Java source file
and the order
+in which the each part should be presented. No rules on programming style, naming conventions
or indentation are given here.
+
+1. Java source files must have a ".java" suffix (this will be enforced by the compiler) [mandatory].
+2. The basename of a Java source file must be the same as the public class defined therein
+   (this will be enforced by the compiler) [mandatory].
+3. Only one class should be defined per source file (except for inner classes and one-shot
uses
+   where the non-public class cannot conceivably be used outside of its context) [mandatory].
+4. Source files should not exceed 1500 lines [recommended].
+5. No line in a source file should exceed 120 characters [mandatory].
+6. The sections of a source file should be presented in the following order [mandatory]:
+   * File information comment (see rule 7 below).
+   * Package name (see rules 1 to 3 in the section 2.1 above and rule 8 below).
+   * Imports (see rules 9 to 10 below).
+   * Other class definitions.
+   * Public class definition.
+7. Do not use automatically expanded log or revision number provided by your source code
management system
+   unless it provides a facility to avoid "false conflicts" when doing merges due simply
to revision number changes
+   (which happens, for example, with cvs when branches are used). [mandatory]
+8. Every class that is to be released must be a member of a package [mandatory].
+    Rationale: classes that are not explicitly put in a package are placed in the unnamed
package by the compiler.
+    Therefore as the classes from many developers will be being placed in the same package
the likelihood of a name
+    clash is greatly increased.
+9. All class imports from the same package should be grouped together. A single blank line
should separate imports
+   from different packages [recommended].
+10. Use javadoc tags and use HTML mark-up to enhance the readability of the output files
[mandatory].
+
+### Java Elements
+
+This section gives advice on coding the various elements of the Java programming language.
+
+#### Class definitions
+
+This section gives guidelines for class and interface definitions in Java.
+The term class in this section is used more broadly to mean class and interface:
+
+1. Class names should start with a capital letter with every subsequent word capitalised,
+   for example: `DataProcessor` [mandatory].
+2. All classes should be preceded by a javadoc comment describing the purpose of the class
[recommended].
+3. Class-level javadoc comments should specify the thread-safety of the class [recommended].
+4. The name of exception classes should end in the word exception, for example: UnknownMungeException
[mandatory].
+5. Class names should in general not be overloaded. For example, defining a class "com.foo.bar.String"
+    should be avoided as there is already a class "java.lang.String" [recommended].
+    Rationale: adhering to this rule reduces the likelihood of confusion and means that the
use of fully qualified
+    class names should not be required.
+6. The definition of the primary class (i.e. the class with the same name as the java file)
should start in column 0
+   of the source file. Inner class definitions should be indented 4 spaces more than their
enclosing class [mandatory].
+7. Declare a class as final only if specialisation will never be required and improved performance
is essential.
+   With modern JVMs there in fact may be no performance advantage. Warning: use of final
limits code reuse [mandatory].
+8. For all but simplest classes the following methods should have useful definitions [recommended]:
+    ```java
+        public boolean equals(Object obj)
+        public int hashCode()
+        public String toString()
+    ```
+9. The order of presentation of the sections in a class should be [mandatory]:
+   * Variables
+   * Methods
+
+#### Variables
+This section gives guidelines for class and instance variable definitions in Java.
+In this section if a rule uses the term variable rather than instance variable or class variable,
+then the rule applies to both types of variable.
+
+1. The order of presentation of variables in a class definition should be [recommended]:
+    * private, protected, public: static final variables (aka constant class variables).
+    * private, protected, public: static variables (aka class variables).
+    * private, protected, public: final variables (aka constant instance variables).
+    * private, protected, public: variables (aka instance variables).
+    It should be noted that as javadoc will automatically order variables in a consistent
manner,
+    rigid adherence to this rule is not necessary.
+2. Variable modifiers should be presented in the following order: static, final, transient,
volatile [mandatory].
+3. The names of static final variables should be upper case with subsequent words prefixed
with an underscore [mandatory].
+   For example:
+    ```java
+    public static final int NOT_FOUND = -1;
+    ```
+4. When a subclass refers to a static final variable defined in a parent class, access should
be qualified
+    by specifying the defining class name [mandatory].
+    For example: use `ParentClass.MAX` rather than `MAX`.
+5. The names of variables (other that static final) should start with a lower case letter.
+   Any words that are contained in the rest of the variable name should be capitalised [mandatory].
+    For example:
+    ```java
+    String name;
+    String[] childrensNames;
+     ```
+6. Class and instance variables must be prefixed with an underscore (_) [mandatory].
+7. Variables must not be named using the so-called Hungarian notation [mandatory].
+   For example:
+    ```java
+    int nCount = 4; // not allowed
+    ```
+8. Only one variable may be defined per line [mandatory].
+9. Variable declarations should be indented 4 spaces more than their enclosing class [mandatory].
+10. All variables should be preceded by a javadoc comment that specifies what the variable
is for,
+    where it is used and so forth. The comment should be of the following form and be indented
+    to the same level as the variable it refers to [recommended]
+11. Never declare instance variables as public unless the class is effectively a "struct"
[mandatory].
+12. Never give a variable the same name as a variable in a superclass [mandatory].
+13. Ensure that all non-private class variables have sensible values even if no instances
have been created
+    (use static initialisers if necessary, i.e.`static { ... }`) [mandatory].
+    Rationale: prevents other objects accessing fields with undefined/unexpected values.
+
+#### Methods
+This section gives guidelines for class and instance method definitions in Java.
+In this section if a rule uses the term method rather than instance method or class method,
+then the rule applies to both types of method.
+
+1. Constructors and finalize methods should follow immediately after the variable declarations
[mandatory].
+2. Do not call non-final methods from constructors. This can lead to unexpected results when
the class is subclassed.
+   If you must call non-final methods from constructors, document this in the constructor's
javadoc [mandatory].
+   Note that private implies final.
+3. Methods that are associated with the same area of functionality should be physically close
to one another [recommended].
+4. After grouping by functionality, methods should be presented in the following order [recommended]:
+   * private, protected, public: static methods.
+   * private, protected, public: instance methods.
+    It should be noted that as javadoc will automatically order methods in a consistent manner,
+    rigid adherence to this rule is not necessary.
+5. Method modifiers should be presented in the following order: abstract, static, final.,
synchronized [mandatory]
+6. When a synchronized method is overloaded, it should be explicitly synchronized in the
subclass [recommended].
+7. Method names should start with a lower case letter with all subsequent words being capitalised
[mandatory].
+   For example:
+    ```java
+    protected int resize(int newSize)
+    protected void addContentsTo(Container destinationContainer)
+    ```
+8. Methods which get and set values should be named as follows [mandatory]:
+    ```java
+    Type getVariableName()
+    void setVariableName(Type newValue)
+    ```
+    Exceptions should be used to report any failure to get or set a value.
+    The "@param" description should detail any assumptions made by the implementation,
+     for example: "Specifying a null value will cause an error to be reported".
+9. Method definitions should be indented 4 spaces more than their enclosing class [mandatory].
+10. All non-private methods should be preceded by a javadoc comment specifying what the method
is for,
+    detailing all arguments, returns and possible exceptions [mandatory]
+11. The braces associated with a method should be on a line on their own and be indented
to the same level
+    as the method [mandatory]. For example:
+    ```java
+    public void munge()
+    {
+        int i;
+        // method definition omitted...
+    }
+    ```
+12. The body of a method should be indented 4 columns further that the opening and closing
braces associated with it [mandatory].
+    See the above rule for an example.
+13. When declaring and calling methods there should be no white space before or after the
parenthesis [mandatory].
+14. In argument lists there should be no white space before a comma, and only a single space
(or newline) after it [mandatory].
+    For example:
+    ```java
+    public void munge(int depth, String name)
+    {
+        if (depth > 0)
+        {
+            munge(depth - 1, name);
+        }
+        // do something
+    }
+    ```
+15. Wherever reasonable define a default constructor (i.e. one that takes no arguments)
+    so that `Class.newInstance()` may be used [recommended]. If an instance which was created
by default construction
+    could be used until further initialisation has been performed, then all unserviceable
requests should cause
+    a runtime exception to be thrown.
+16. The method public static void main() should not be used for test purposes.
+    Instead a test/demo program should be supplied separately. [mandatory].
+17. Public access methods (i.e. methods that get and set attributes) should only be supplied
when required [mandatory].
+18. If an instance method has no natural return value, declare it as void rather than using
the "return this;"
+    convention [mandatory].
+19. Ensure that non-private static methods behave sensibly if no instances of the defining
class have been created [mandatory].
+
+### Expressions
+This section defines the rules to be used for Java expressions:
+
+1. Unary operators should not be separated from their operand by white space [mandatory].
+2. Embedded ++ or – operators should only be used when it improves code clarity [recommended].
This is rare.
+3. Extra parenthesis should be used in expressions to improve their clarity [recommended].
+4. The logical expression operand of the "?:" (ternary) operator must be enclosed in parenthesis.
+   If the other operands are also expressions then they should also be enclosed in parenthesis
[mandatory]. For example:
+    ```java
+    biggest = (a > b) ? a : b;
+    complex = (a + b > 100) ? (100 * c) : (10 * d);
+    ```
+5. Nested "?:" (ternary) operators can be confusing and should be avoided [mandatory].
+6. Use of the binary "," operator (the comma operator) should be avoided [mandatory].
+   Putting all the work of a for loop on a single line is not a sign of great wisdom and
talent.
+7. If an expression is too long for a line (i.e. extends beyond column 119) then it should
be split after the lowest
+   precedence operator near the break [mandatory]. For example:
+    ```java
+    if ((state == NEED_TO_REPLY) ||
+        (state == REPLY_ACK_TIMEOUT))
+    {
+        // (re)send the reply and enter state WAITING_FOR_REPLY_ACK
+    }
+    ```
+    Furthermore if an expression requires to be split more than once, then the split should
occur at the same logical
+    level if possible.
+8. All binary and ternary operators (exception for ".") should be separated from their operands
by a space [mandatory].
+
+### Statements
+
+#### Simple Statements
+
+This section defines the general rules for simple Java statements:
+
+1. There must only be one statement per line [mandatory].
+2. In general local variables should be named in a similar manner to instance variables [recommended].
+3. More than one temporary variable may be declared on a single line provided no initialisers
are used [mandatory].
+   For example:
+    ```java
+    int j, k = 10, l;  // Incorrect!
+    int j, l;          // Correct
+    int k = 10;
+     ```
+4. A null body for a while, for, if, etc. should be documented so that it is clearly intentional
[mandatory].
+5. Keywords that are followed by a parenthesised expression (such as while, if, etc) should
be separated from
+   the open bracket by a single space [mandatory]. For example:
+    ```java
+    if (a > b)
+    {
+        munge();
+    }
+     ```
+6. In method calls, there should be no spaces before or after the parentheses [mandatory].
For example:
+    ```java
+    munge (a, 10);    // Incorrect!
+    munge(a, 10);     // Correct.
+     ```
+#### Compound Statements
+This section defines the general rules associated with compound statements in Java:
+
+1.  The body of a compound statement should be indented by 4 spaces more than the enclosing
braces [mandatory].
+    See the following rule for an example.
+2.  The braces associated with a compound statement should be on their own line and be indented
to the same level
+    as the surrounding code [mandatory]. For example:
+    ```java
+    if ((length >= LEN_BOX) && (width >= WID_BOX))
+    {
+        int i;
+        // Statements omitted...
+    }
+     ```
+3.  If the opening and closing braces associated with a compound statement are further than
20 lines apart
+     then the closing brace should annotated as follows [mandatory]:
+    ```java
+    for (int j = 0; j < SIZE; j++)
+    {
+        lotsOfCode();
+    } // end for
+     ```
+4. All statements associated with an if or if-else statement should be made compound by the
use of braces [mandatory].
+   For example:
+    ```java
+    if (a > b)
+    {
+        statement();
+    }
+    else
+    {
+        statement1();
+        statement2();
+    }
+     ```
+5. The case labels in a switch statement should be on their own line and indented by a further
4 spaces.
+   The statements associated with the label should be indented by 4 columns more than the
label and not be enclosed
+    in a compound statement. [mandatory]. For example:
+    ```java
+    switch (tState)
+    {
+        case NOT_RUNNING:
+            start();
+            break;
+
 
 Review comment:
   Is empty line is also mandatory? Empty line is not mentioned in description
 
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> [Broker-J] Create a developer guide for Qpid Broker-J
> -----------------------------------------------------
>
>                 Key: QPID-8361
>                 URL: https://issues.apache.org/jira/browse/QPID-8361
>             Project: Qpid
>          Issue Type: Task
>          Components: Broker-J
>            Reporter: Alex Rudyy
>            Priority: Major
>             Fix For: qpid-java-broker-8.0.0
>
>
> The developer documentation is currently scattered over various Qpid confluence pages.
It could be challenging for people interested in contributing to the project to find that
documentation. A developer guide could be added to cover such aspects as
> * Environment Setup
> * Building project
> * Running tests
> * Releasing
> * Architecture overview
> The following wiki pages are good candidates for inclusion into a developer guide:
> [High Level Architecture|https://cwiki.apache.org/confluence/display/qpid/High+Level+Architecture]
> [How To Build Qpid Broker-J|https://cwiki.apache.org/confluence/display/qpid/How+To+Build+Qpid+Broker-J]
> [Releasing Qpid Broker-J|https://cwiki.apache.org/confluence/display/qpid/Releasing+Qpid+Broker-J]
> The wiki pages below might be included as well
> [Java Coding Standards|https://cwiki.apache.org/confluence/display/qpid/Java+Coding+Standards]
> [Qpid Java Run Scripts|https://cwiki.apache.org/confluence/display/qpid/Qpid+Java+Run+Scripts]
> The developer documentation should be easy to modify, maintain and preview. Thus, it
can be written in  markdown or [asciidoc|https://asciidoctor.org/docs/asciidoc-syntax-quick-reference/].
The latter is also supported on github. 
> Potentially, it can be published on Qpid  project site as part of release process.



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