SAMMessage->header —
The header properties of the message.
Описание
SAMMessage
object$header;
The header property is a container for any system or
user properties that area associated with the message.
Properties may be assigned by the sender of a message to control the way
the messaging systems handles it or may be assigned by the messaging
system itself to tell the recipient extra information about the message or
the way in which it has been handled.
Some properties are understood by SAM in which case constants have been
defined for them. The majority of properties however are ignored by the
SAM implementation and simply passed through to the underlying messaging
systems allowing the application to use messaging specific property names
or to define its own "user" properties.
The SAM defined properties are as follows:
Property name
Possible values
SAM_MESSAGEID
When a message is received this field contains the unique
identifier of the message as allocated by the underlying
messaging system. When sending a message this field is ignored.
SAM_REPLY_TO
A string providing the identity of the queue on to which
responses to this message should be posted.
SAM_TYPE
An indication of the type of message to be sent. The value may be
SAM_TEXT indicating the contents of the
message body is a text string, or SAM_BYTES
indicating the contents of the message body are some application
defined format.
The way in which this property is used may depend on the underlying
messaging server. For instance a messaging server that supports the
JMS (Java Message Service) specification may interpret this value and
send messages of type "jms_text" and "jms_bytes". In addition, if
the SAM_TYPE property is set to SAM_TEXT the
data provided for the message body is expected to be a UTF8 encoded
string.
When setting the values of properties it is often useful to give a hint as
to the format in which the property should be delivered to the messaging
system. By default property values are delivered as text and the
following simple syntax may be used to set a value:
Пример #1 Setting a text format property using the default syntax
<?php $msg = new SAMMessage();
$msg->header->myPropertyName = 'textData'; ?>
If it is desired to pass type information an alternative syntax may be
used where the value and the type hint are passed in an associative
array:
Пример #2 Setting a text format property using a type hint
When passing a type hint the type entry should be one of the SAM defined
constant values as defined by the following table:
Constant
Type description
SAM_BOOLEAN
Any value passed will be interpreted as logical true or false.
If the value cannot be interpreted as a PHP boolean value the value
passed to the messaging system is undefined.
SAM_BYTE
An 8-bit signed integer value. SAM will attempt to convert the
property value specified into a single byte value to pass to the
messaging system. If a string value is passed an attempt will be
made to interpret the string as a numeric value. If the numeric
value cannot be expressed as an 8-bit signed binary value data may
be lost in the conversion.
SAM_DOUBLE
A long floating point value. SAM will attempt to convert the
property value specified into a floating point value with 15 digits
of precision. If a string value is passed an attempt will be made to
interpret the string as a numeric value. If the passed value cannot
be expressed as a 15 digit floating point value data may be lost in
the conversion.
SAM_FLOAT
A short floating point value. SAM will attempt to convert the
property value specified into a floating point value with 7 digits of
precision. If a string value is passed an attempt will be made to
interpret the string as a numeric value. If the passed value cannot
be expressed as a 7 digit floating point value data may be lost in
the conversion.
SAM_INT
An 32-bit signed integer value. SAM will attempt to convert the
property value specified into a 32-bit value to pass to the messaging
system. If a string value is passed an attempt will be made to
interpret the string as a numeric value. If the numeric value cannot
be expressed as an 32-bit signed binary value data may be lost in the
conversion.
SAM_LONG
An 64-bit signed integer value. SAM will attempt to convert the
property value specified into a 64-bit value to pass to the messaging
system. If a string value is passed an attempt will be made to
interpret the string as a numeric value. If the numeric value cannot
be expressed as an 64-bit signed binary value data may be lost in the
conversion.
SAM_STRING
SAM will interpret the property value specified as a string and pass
it to the messaging system accordingly.
Примеры
Пример #3 Setting properties as the sender of a message
<?php $msg = new SAMMessage('This is a test message');
// defining SAM specific properties... $msg->header->SAM_REPLY_TO = 'queue://test/replyQueue';
// defining arbitrary properties... // // a default string property $msg->header->myStringProp1 = 'a string property'; // a string property with a type hint $msg->header->myStringProp2 = array('another string property', SAM_STRING);
// a boolean property $msg->header->myBoolProp = array(FALSE, SAM_BOOL);
