== Sequence Diagram


== Basic examples
The sequence `+->+` is used to draw a message between two
participants.
Participants do not have to be explicitly declared.

To have a dotted arrow, you use `+-->+`

It is also possible to use `+<-+` and `+<--+`.
That does not change the drawing, but may improve readability.
Note that this is only true for sequence diagrams, rules are different for the other diagrams.
<plantuml>
@startuml
Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

Alice -> Bob: Another authentication Request
Alice <-- Bob: Another authentication Response
@enduml
</plantuml>


== Declaring participant

If the keyword `+participant+` is used to declare a participant, more control on that participant is possible.

The order of declaration will be the (default) **order of display**.

Using these other keywords to declare participants will **change the shape** of the participant representation:
* `+actor+`
* `+boundary+`
* `+control+`
* `+entity+`
* `+database+`
* `+collections+`
* `+queue+`

<plantuml>
@startuml
participant participant as Foo
actor       actor       as Foo1
boundary    boundary    as Foo2
control     control     as Foo3
entity      entity      as Foo4
database    database    as Foo5
collections collections as Foo6
queue       queue       as Foo7
Foo -> Foo1 : To actor 
Foo -> Foo2 : To boundary
Foo -> Foo3 : To control
Foo -> Foo4 : To entity
Foo -> Foo5 : To database
Foo -> Foo6 : To collections
Foo -> Foo7: To queue
@enduml
</plantuml>

Rename a participant using the `+as+` keyword.

You can also change the background link::color[color] of
actor or participant.

<plantuml>
@startuml
actor Bob #red
' The only difference between actor
'and participant is the drawing
participant Alice
participant "I have a really\nlong name" as L #99FF99
/' You can also declare:
   participant L as "I have a really\nlong name"  #99FF99
  '/

Alice->Bob: Authentication Request
Bob->Alice: Authentication Response
Bob->L: Log transaction
@enduml
</plantuml>

You can use the `+order+` keyword to customize the display order of participants.

<plantuml>
@startuml
participant Last order 30
participant Middle order 20
participant First order 10
@enduml
</plantuml>


== Use non-letters in participants


You can use quotes to define participants.
And you can use the `+as+` keyword to give an alias to those participants.
<plantuml>
@startuml
Alice -> "Bob()" : Hello
"Bob()" -> "This is very\nlong" as Long
' You can also declare:
' "Bob()" -> Long as "This is very\nlong"
Long --> "Bob()" : ok
@enduml
</plantuml>



== Message to Self

A participant can send a message to itself.

It is also possible to have multi-line using `+\n+`.

<plantuml>
@startuml
Alice->Alice: This is a signal to self.\nIt also demonstrates\nmultiline \ntext
@enduml
</plantuml>



== Text alignment

=== Text of response message below the arrow

You can put the text of the response message below the arrow, with the `+skinparam responseMessageBelowArrow true+` command.

<plantuml>
@startuml
skinparam responseMessageBelowArrow true
Bob -> Alice : hello
Alice -> Bob : ok
@enduml
</plantuml>

[[#FFD700#TODO]] Link to Text Alignment on link::skinparam[skinparam] page.


== Change arrow style

You can change arrow style by several ways:
* add a final `+x+` to denote a lost message
* use `+\+` or `+/+` instead of `+<+` or `+>+` to have only the bottom or top part of the arrow
* repeat the arrow head (for example, `+>>+` or `+//+`) head to have a thin drawing
* use `+--+` instead of `+-+` to have a dotted arrow
* add a final "o" at arrow head
* use bidirectional arrow `+<->+`

<plantuml>
@startuml
Bob ->x Alice
Bob -> Alice
Bob ->> Alice
Bob -\ Alice
Bob \\- Alice
Bob //-- Alice

Bob ->o Alice
Bob o\\-- Alice

Bob <-> Alice
Bob <->o Alice
@enduml
</plantuml>



== Change arrow color

You can change the color of individual arrows using the following notation:
<plantuml>
@startuml
Bob -[#red]> Alice : hello
Alice -[#0000FF]->Bob : ok
@enduml
</plantuml>



== Message sequence numbering


The keyword `+autonumber+` is used to
automatically add number to messages.

<plantuml>
@startuml
autonumber
Bob -> Alice : Authentication Request
Bob <- Alice : Authentication Response
@enduml
</plantuml>

You can specify a startnumber with `+autonumber //start//+` , and
also an increment with `+autonumber //start// //increment//+`.


<plantuml>
@startuml
autonumber
Bob -> Alice : Authentication Request
Bob <- Alice : Authentication Response

autonumber 15
Bob -> Alice : Another authentication Request
Bob <- Alice : Another authentication Response

autonumber 40 10
Bob -> Alice : Yet another authentication Request
Bob <- Alice : Yet another authentication Response

@enduml
</plantuml>


You can specify a format for your number by using between double-quote.

The formatting is done with the Java class `+DecimalFormat+`
(`+0+` means digit, `+#+` means digit and zero if absent).

You can use some html tag in the format.
<plantuml>
@startuml
autonumber "<b>[000]"
Bob -> Alice : Authentication Request
Bob <- Alice : Authentication Response

autonumber 15 "<b>(<u>##</u>)"
Bob -> Alice : Another authentication Request
Bob <- Alice : Another authentication Response

autonumber 40 10 "<font color=red><b>Message 0  "
Bob -> Alice : Yet another authentication Request
Bob <- Alice : Yet another authentication Response

@enduml
</plantuml>

You can also use `+autonumber stop+` and
`+autonumber resume //increment// //format//+` to respectively pause and resume
automatic numbering.

<plantuml>
@startuml
autonumber 10 10 "<b>[000]"
Bob -> Alice : Authentication Request
Bob <- Alice : Authentication Response

autonumber stop
Bob -> Alice : dummy

autonumber resume "<font color=red><b>Message 0  "
Bob -> Alice : Yet another authentication Request
Bob <- Alice : Yet another authentication Response

autonumber stop
Bob -> Alice : dummy

autonumber resume 1 "<font color=blue><b>Message 0  "
Bob -> Alice : Yet another authentication Request
Bob <- Alice : Yet another authentication Response
@enduml
</plantuml>



== Page Title, Header and Footer

The `+title+` keyword is used to add a title to the page.

Pages can display headers and footers using `+header+` and `+footer+`.

<plantuml>
@startuml

header Page Header
footer Page %page% of %lastpage%

title Example Title

Alice -> Bob : message 1
Alice -> Bob : message 2

@enduml
</plantuml>




== Splitting diagrams


The `+newpage+` keyword is used to split a diagram into several images.

You can put a title for the new page just after the `+newpage+`
keyword.  This title overrides the previously specified title if any.

This is very handy with __Word__ to print long diagram on
several pages.

(Note: this really does work.  Only the first page is shown below, but it is a display artifact.)

<plantuml>
@startuml

Alice -> Bob : message 1
Alice -> Bob : message 2

newpage

Alice -> Bob : message 3
Alice -> Bob : message 4

newpage A title for the\nlast page

Alice -> Bob : message 5
Alice -> Bob : message 6
@enduml
</plantuml>



== Grouping message


It is possible to group messages together using the following
keywords:
* `+alt/else+`
* `+opt+`
* `+loop+`
* `+par+`
* `+break+`
* `+critical+`
* `+group+`, followed by a text to be displayed


It is possible to add a text that will be displayed into the
header (for `+group+`, see next paragraph __'Secondary group label'__).

The `+end+` keyword is used to close the group.

Note that it is possible to nest groups.

<plantuml>
@startuml
Alice -> Bob: Authentication Request

alt successful case

    Bob -> Alice: Authentication Accepted

else some kind of failure

    Bob -> Alice: Authentication Failure
    group My own label
    Alice -> Log : Log attack start
        loop 1000 times
            Alice -> Bob: DNS Attack
        end
    Alice -> Log : Log attack end
    end

else Another type of failure

   Bob -> Alice: Please repeat

end
@enduml
</plantuml>


== Secondary group label

For `+group+`, it is possible to add, between`+[+` and `+]+`, a secondary text or label that will be displayed into the header.

<plantuml>
@startuml
Alice -> Bob: Authentication Request
Bob -> Alice: Authentication Failure
group My own label [My own label 2]
    Alice -> Log : Log attack start
    loop 1000 times
        Alice -> Bob: DNS Attack
    end
    Alice -> Log : Log attack end
end
@enduml
</plantuml>

__[Ref. https://forum.plantuml.net/2503[QA-2503]]__


== Notes on messages

It is possible to put notes on message using the `+note left+`
or `+note right+` keywords __just after the message__.

You can have a multi-line note using the `+end note+`
keywords.

<plantuml>
@startuml
Alice->Bob : hello
note left: this is a first note

Bob->Alice : ok
note right: this is another note

Bob->Bob : I am thinking
note left
a note
can also be defined
on several lines
end note
@enduml
</plantuml>



== Some other notes


It is also possible to place notes relative to participant with
`+note left of+` , `+note right of+` or `+note over+` keywords.


It is possible to highlight a note by changing its background
link::color[color].

You can also have a multi-line note using the `+end note+`
keywords.

<plantuml>
@startuml
participant Alice
participant Bob
note left of Alice #aqua
This is displayed
left of Alice.
end note

note right of Alice: This is displayed right of Alice.

note over Alice: This is displayed over Alice.

note over Alice, Bob #FFAAAA: This is displayed\n over Bob and Alice.

note over Bob, Alice
This is yet another
example of
a long note.
end note
@enduml
</plantuml>



== Changing notes shape

You can use `+hnote+` and `+rnote+` keywords
to change note shapes.
<plantuml>
@startuml
caller -> server : conReq
hnote over caller : idle
caller <- server : conConf
rnote over server
 "r" as rectangle
 "h" as hexagon
endrnote
@enduml
</plantuml>



== Creole and HTML

link::creole[It is also possible to use creole formatting:]

<plantuml>
@startuml
participant Alice
participant "The **Famous** Bob" as Bob

Alice -> Bob : hello --there--
... Some ~~long delay~~ ...
Bob -> Alice : ok
note left
  This is **bold**
  This is //italics//
  This is ""monospaced""
  This is --stroked--
  This is __underlined__
  This is ~~waved~~
end note

Alice -> Bob : A //well formatted// message
note right of Alice
 This is <back:cadetblue><size:18>displayed</size></back>
 __left of__ Alice.
end note
note left of Bob
 <u:red>This</u> is <color #118888>displayed</color>
 **<color purple>left of</color> <s:red>Alice</strike> Bob**.
end note
note over Alice, Bob
 <w:#FF33FF>This is hosted</w> by <img sourceforge.jpg>
end note
@enduml
</plantuml>



== Divider or separator


If you want, you can split a diagram using `+==+` separator to
divide your diagram into logical steps.
<plantuml>
@startuml

== Initialization ==

Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

== Repetition ==

Alice -> Bob: Another authentication Request
Alice <-- Bob: another authentication Response

@enduml
</plantuml>


== Reference

You can use reference in a diagram, using the keyword `+ref over+`.
<plantuml>
@startuml
participant Alice
actor Bob

ref over Alice, Bob : init

Alice -> Bob : hello

ref over Bob
  This can be on
  several lines
end ref
@enduml
</plantuml>



== Delay

You can use `+...+` to indicate a delay in the diagram.
And it is also possible to put a message with this delay.
<plantuml>
@startuml

Alice -> Bob: Authentication Request
...
Bob --> Alice: Authentication Response
...5 minutes later...
Bob --> Alice: Good Bye !

@enduml
</plantuml>


== Text wrapping

To break long messages, you can manually add `+\n+` in your text.

Another option is to use `+maxMessageSize+` setting:

<plantuml>
@startuml
skinparam maxMessageSize 50
participant a
participant b
a -> b :this\nis\nmanually\ndone
a -> b :this is a very long message on several words
@enduml
</plantuml>


== Space


You can use `+|||+` to indicate some spacing in the diagram.

It is also possible to specify a number of pixel to be used.
<plantuml>
@startuml

Alice -> Bob: message 1
Bob --> Alice: ok
|||
Alice -> Bob: message 2
Bob --> Alice: ok
||45||
Alice -> Bob: message 3
Bob --> Alice: ok

@enduml
</plantuml>



== Lifeline Activation and Destruction

The `+activate+` and `+deactivate+` are used to denote
participant activation.

Once a participant is activated, its lifeline appears.

The `+activate+` and `+deactivate+` apply on
the previous message.

The `+destroy+` denote the end of the lifeline of a
participant.

<plantuml>
@startuml
participant User

User -> A: DoWork
activate A

A -> B: << createRequest >>
activate B

B -> C: DoWork
activate C
C --> B: WorkDone
destroy C

B --> A: RequestCreated
deactivate B

A -> User: Done
deactivate A

@enduml
</plantuml>


Nested lifeline can be used, and it is possible to add a
link::color[color] on the
lifeline.

<plantuml>
@startuml
participant User

User -> A: DoWork
activate A #FFBBBB

A -> A: Internal call
activate A #DarkSalmon

A -> B: << createRequest >>
activate B

B --> A: RequestCreated
deactivate B
deactivate A
A -> User: Done
deactivate A

@enduml
</plantuml>

Autoactivation is possible and works with the return keywords:

<plantuml>
@startuml
autoactivate on
alice -> bob : hello
bob -> bob : self call
bill -> bob #005500 : hello from thread 2
bob -> george ** : create
return done in thread 2
return rc
bob -> george !! : delete
return success

@enduml
</plantuml>



== Return

Command `+return+` generates a return message with optional text label.

The return point is that which caused the most recent life-line activation.

The syntax is `+return label+` where `+label+` if provided is any string acceptable for conventional messages.


<plantuml>
@startuml
Bob -> Alice : hello
activate Alice
Alice -> Alice : some action
return bye
@enduml
</plantuml>



== Participant creation


You can use the `+create+` keyword just before the first
reception of a message to emphasize the fact that this message is
actually __creating__ this new object.
<plantuml>
@startuml
Bob -> Alice : hello

create Other
Alice -> Other : new

create control String
Alice -> String
note right : You can also put notes!

Alice --> Bob : ok

@enduml
</plantuml>



== Shortcut syntax for activation, deactivation, creation


Immediately after specifying the target participant, the following syntax can be used:

* `++++` Activate the target (optionally a #color may follow this)
* `+--+` Deactivate the source
* `+**+` Create an instance of the target
* `+!!+` Destroy an instance of the target

<plantuml>
@startuml
alice -> bob ++ : hello
bob -> bob ++ : self call
bob -> bib ++  #005500 : hello
bob -> george ** : create
return done
return rc
bob -> george !! : delete
return success
@enduml
</plantuml>



== Incoming and outgoing messages

You can use incoming or outgoing arrows if you want to focus on a part
of the diagram.

Use square brackets to denote the left "`+[+`" or the
right "`+]+`" side of the diagram.
<plantuml>
@startuml
[-> A: DoWork

activate A

A -> A: Internal call
activate A

A ->] : << createRequest >>

A<--] : RequestCreated
deactivate A
[<- A: Done
deactivate A
@enduml
</plantuml>


You can also have the following syntax:
<plantuml>
@startuml
participant Alice
participant Bob #lightblue
Alice -> Bob
Bob -> Carol
...
[-> Bob
[o-> Bob
[o->o Bob
[x-> Bob
...
[<- Bob
[x<- Bob
...
Bob ->]
Bob ->o]
Bob o->o]
Bob ->x]
...
Bob <-]
Bob x<-]

@enduml
</plantuml>


== Short arrows for incoming and outgoing messages

You can have **short** arrows with using `+?+`.

<plantuml>
@startuml
?-> Alice    : ""?->""\n**short** to actor1
[-> Alice    : ""[->""\n**from start** to actor1
[-> Bob      : ""[->""\n**from start** to actor2
?-> Bob      : ""?->""\n**short** to actor2
Alice ->]    : ""->]""\nfrom actor1 **to end**
Alice ->?    : ""->?""\n**short** from actor1
Alice -> Bob : ""->"" \nfrom actor1 to actor2
@enduml
</plantuml>

__[Ref. https://forum.plantuml.net/310[QA-310]]__


== Anchors and Duration



With `+teoz+` usage it is possible to add anchors to the diagram and use the anchors to specify duration time.
<plantuml>
@startuml
!pragma teoz true

{start} Alice -> Bob : start doing things during duration
Bob -> Max : something
Max -> Bob : something else
{end} Bob -> Alice : finish

{start} <-> {end} : some time

@enduml
</plantuml>



== Stereotypes and Spots



It is possible to add stereotypes to participants using `+<<+`
and `+>>+`.

In the stereotype, you can add a spotted character
in a colored circle using the syntax `+(X,color)+`.
<plantuml>
@startuml

participant "Famous Bob" as Bob << Generated >>
participant Alice << (C,#ADD1B2) Testable >>

Bob->Alice: First message

@enduml
</plantuml>

By default, the __guillemet__ character is used to display the stereotype.
You can change this behavious using the skinparam `+guillemet+`:

<plantuml>
@startuml

skinparam guillemet false
participant "Famous Bob" as Bob << Generated >>
participant Alice << (C,#ADD1B2) Testable >>

Bob->Alice: First message

@enduml
</plantuml>

<plantuml>
@startuml

participant Bob << (C,#ADD1B2) >>
participant Alice << (C,#ADD1B2) >>

Bob->Alice: First message

@enduml
</plantuml>



== More information on titles

You can use link::creole[creole formatting] in the title.

<plantuml>
@startuml

title __Simple__ **communication** example

Alice -> Bob: Authentication Request
Bob -> Alice: Authentication Response

@enduml
</plantuml>
You can add newline using `+\n+` in the title description.
<plantuml>
@startuml

title __Simple__ communication example\non several lines

Alice -> Bob: Authentication Request
Bob -> Alice: Authentication Response

@enduml
</plantuml>
You can also define title on several lines using `+title+`
and `+end title+` keywords.
<plantuml>
@startuml

title
 <u>Simple</u> communication example
 on <i>several</i> lines and using <font color=red>html</font>
 This is hosted by <img:sourceforge.jpg>
end title

Alice -> Bob: Authentication Request
Bob -> Alice: Authentication Response

@enduml
</plantuml>



== Participants encompass



It is possible to draw a box around some participants, using `+box+`
and `+end box+` commands.

You can add an optional title or a
optional background color, after the `+box+` keyword.

<plantuml>
@startuml

box "Internal Service" #LightBlue
participant Bob
participant Alice
end box
participant Other

Bob -> Alice : hello
Alice -> Other : hello

@enduml
</plantuml>



== Removing Foot Boxes

You can use the `+hide footbox+` keywords to remove the foot boxes
of the diagram.

<plantuml>
@startuml

hide footbox
title Foot Box removed

Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

@enduml
</plantuml>



== Skinparam


You can use the link::skinparam[skinparam]
command to change colors and fonts for the drawing.


You can use this command:
* In the diagram definition, like any other commands,
* In an link::preprocessing[included file],
* In a configuration file, provided in the link::command-line[command line] or the link::ant-task[ANT task].

You can also change other rendering parameter, as seen in the following examples:

<plantuml>
@startuml
skinparam sequenceArrowThickness 2
skinparam roundcorner 20
skinparam maxmessagesize 60
skinparam sequenceParticipant underline

actor User
participant "First Class" as A
participant "Second Class" as B
participant "Last Class" as C

User -> A: DoWork
activate A

A -> B: Create Request
activate B

B -> C: DoWork
activate C
C --> B: WorkDone
destroy C

B --> A: Request Created
deactivate B

A --> User: Done
deactivate A

@enduml
</plantuml>

<plantuml>
@startuml
skinparam backgroundColor #EEEBDC
skinparam handwritten true

skinparam sequence {
ArrowColor DeepSkyBlue
ActorBorderColor DeepSkyBlue
LifeLineBorderColor blue
LifeLineBackgroundColor #A9DCDF

ParticipantBorderColor DeepSkyBlue
ParticipantBackgroundColor DodgerBlue
ParticipantFontName Impact
ParticipantFontSize 17
ParticipantFontColor #A9DCDF

ActorBackgroundColor aqua
ActorFontColor DeepSkyBlue
ActorFontSize 17
ActorFontName Aapex
}

actor User
participant "First Class" as A
participant "Second Class" as B
participant "Last Class" as C

User -> A: DoWork
activate A

A -> B: Create Request
activate B

B -> C: DoWork
activate C
C --> B: WorkDone
destroy C

B --> A: Request Created
deactivate B

A --> User: Done
deactivate A

@enduml
</plantuml>




== Changing padding


It is possible to tune some padding settings.

<plantuml>
@startuml
skinparam ParticipantPadding 20
skinparam BoxPadding 10

box "Foo1"
participant Alice1
participant Alice2
end box
box "Foo2"
participant Bob1
participant Bob2
end box
Alice1 -> Bob1 : hello
Alice1 -> Out : out
@enduml
</plantuml>




== Appendice: Examples of all arrow type

=== Normal arrow
<plantuml>
@startuml
participant Alice as a
participant Bob   as b
a ->     b : ""->   ""
a ->>    b : ""->>  ""
a -\     b : ""-\   ""
a -\\    b : ""-\\\\""
a -/     b : ""-/   ""
a -//    b : ""-//  ""
a ->x    b : ""->x  ""
a x->    b : ""x->  ""
a o->    b : ""o->  ""
a ->o    b : ""->o  ""
a o->o   b : ""o->o ""
a <->    b : ""<->  ""
a o<->o  b : ""o<->o""
a x<->x  b : ""x<->x""
a ->>o   b : ""->>o ""
a -\o    b : ""-\o  ""
a -\\o   b : ""-\\\\o""
a -/o    b : ""-/o  ""
a -//o   b : ""-//o ""
a x->o   b : ""x->o ""
@enduml
</plantuml>

=== Incoming and outgoing messages (with '[', ']')
==== Incoming messages (with '[')
<plantuml>
@startuml
participant Alice as a
participant Bob   as b
[->      b : ""[->   ""
[->>     b : ""[->>  ""
[-\      b : ""[-\   ""
[-\\     b : ""[-\\\\""
[-/      b : ""[-/   ""
[-//     b : ""[-//  ""
[->x     b : ""[->x  ""
[x->     b : ""[x->  ""
[o->     b : ""[o->  ""
[->o     b : ""[->o  ""
[o->o    b : ""[o->o ""
[<->     b : ""[<->  ""
[o<->o   b : ""[o<->o""
[x<->x   b : ""[x<->x""
[->>o    b : ""[->>o ""
[-\o     b : ""[-\o  ""
[-\\o    b : ""[-\\\\o""
[-/o     b : ""[-/o  ""
[-//o    b : ""[-//o ""
[x->o    b : ""[x->o ""
@enduml
</plantuml>

==== Outgoing messages (with ']')
<plantuml>
@startuml
participant Alice as a
participant Bob   as b
a ->]      : ""->]   ""
a ->>]     : ""->>]  ""
a -\]      : ""-\]   ""
a -\\]     : ""-\\\\]""
a -/]      : ""-/]   ""
a -//]     : ""-//]  ""
a ->x]     : ""->x]  ""
a x->]     : ""x->]  ""
a o->]     : ""o->]  ""
a ->o]     : ""->o]  ""
a o->o]    : ""o->o] ""
a <->]     : ""<->]  ""
a o<->o]   : ""o<->o]""
a x<->x]   : ""x<->x]""
a ->>o]    : ""->>o] ""
a -\o]     : ""-\o]  ""
a -\\o]    : ""-\\\\o]""
a -/o]     : ""-/o]  ""
a -//o]    : ""-//o] ""
a x->o]    : ""x->o] ""
@enduml
</plantuml>

=== Short incoming and outgoing messages (with '?')
==== Short incoming (with '?')
<plantuml>
@startuml
participant Alice as a
participant Bob   as b
a ->     b : //Long long label//
?->      b : ""?->   ""
?->>     b : ""?->>  ""
?-\      b : ""?-\   ""
?-\\     b : ""?-\\\\""
?-/      b : ""?-/   ""
?-//     b : ""?-//  ""
?->x     b : ""?->x  ""
?x->     b : ""?x->  ""
?o->     b : ""?o->  ""
?->o     b : ""?->o  ""
?o->o    b : ""?o->o ""
?<->     b : ""?<->  ""
?o<->o   b : ""?o<->o""
?x<->x   b : ""?x<->x""
?->>o    b : ""?->>o ""
?-\o     b : ""?-\o  ""
?-\\o    b : ""?-\\\\o ""
?-/o     b : ""?-/o  ""
?-//o    b : ""?-//o ""
?x->o    b : ""?x->o ""
@enduml
</plantuml>

==== Short outgoing (with '?')
<plantuml>
@startuml
participant Alice as a
participant Bob   as b
a ->     b : //Long long label//
a ->?      : ""->?   ""
a ->>?     : ""->>?  ""
a -\?      : ""-\?   ""
a -\\?     : ""-\\\\?""
a -/?      : ""-/?   ""
a -//?     : ""-//?  ""
a ->x?     : ""->x?  ""
a x->?     : ""x->?  ""
a o->?     : ""o->?  ""
a ->o?     : ""->o?  ""
a o->o?    : ""o->o? ""
a <->?     : ""<->?  ""
a o<->o?   : ""o<->o?""
a x<->x?   : ""x<->x?""
a ->>o?    : ""->>o? ""
a -\o?     : ""-\o?  ""
a -\\o?    : ""-\\\\o?""
a -/o?     : ""-/o?  ""
a -//o?    : ""-//o? ""
a x->o?    : ""x->o? ""
@enduml
</plantuml>


== Specific SkinParameter

=== By default
<plantuml>
@startuml
Bob -> Alice : hello
Alice -> Bob : ok
@enduml
</plantuml>


=== lifelineStrategy solid

In order to have solid life line in sequence diagrams, you can use:
* `+skinparam lifelineStrategy solid+`
<plantuml>
@startuml
skinparam lifelineStrategy solid
Bob -> Alice : hello
Alice -> Bob : ok
@enduml
</plantuml>

__[Ref. https://forum.plantuml.net/2794[QA-2794]]__

=== style strictuml
To be conform to strict UML (__for arrow style: emits triangle rather than sharp arrowheads__), you can use:
* `+skinparam style strictuml+`
<plantuml>
@startuml
skinparam style strictuml
Bob -> Alice : hello
Alice -> Bob : ok
@enduml
</plantuml>
__[Ref. https://forum.plantuml.net/1047[QA-1047]]__


== Hide unlinked participant 

By default, all participants are displayed.
<plantuml>
@startuml
participant Alice
participant Bob
participant Carol

Alice -> Bob : hello
@enduml
</plantuml>

But you can `+hide unlinked+` participant.
<plantuml>
@startuml
hide unlinked
participant Alice
participant Bob
participant Carol

Alice -> Bob : hello
@enduml
</plantuml>


__[Ref. https://forum.plantuml.net/4247[QA-4247]]__