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Syntax for Stringified Proxies

Synopsis

identity -f facet -t -o -O -d -D -s @ adapter_id : endpoints

Description

A stringified proxy consists of an identity, proxy options, and an optional object adapter identifier or endpoint list. White space (the space, tab (\t), line feed (\n), and carriage return (\r) characters) act as token delimiters; if a white space character appears as part of a component of a stringified proxy (such as the identity), it must be quoted or escaped as described below.

A proxy containing an identity with no endpoints, or an identity with an object adapter identifier, represents an indirect proxy that will be resolved using the Ice locator.

Proxy options configure the invocation mode:

The proxy options -t, -o, -O, -d, and -D are mutually exclusive.

The object identity identity is structured as [category/]name, where the category component and slash separator are optional. If identity contains white space or either of the characters : or @, it must be enclosed in single or double quotes. The category and name components are UTF-8 strings that use the encoding described below. Any occurrence of a slash (/) in category or name must be escaped with a backslash (i.e., \/).

The facet argument of the -f option represents a facet name. If facet contains white space, it must be enclosed in single or double quotes. A facet name is a UTF-8 string that uses the encoding described below.

The object adapter identifier adapter_id is a UTF-8 string that uses the encoding described below. If adapter_id contains white space, it must be enclosed in single or double quotes.

Single or double quotes can be used to prevent white space characters from being interpreted as delimiters. Double quotes prevent interpretation of a single quote a as an opening or closing quote, for example:

{zcode}
"a string with a ' quote"
{zcode}

Single quotes prevent interpretation of a double quote as an opening or closing quote. For example:

{zcode}
'a string with a " quote'
{zcode}

Escape sequences such as \b are interpreted within single and double quotes.

UTF-8 strings are encoded using ASCII characters for the ordinal range 32--126 (inclusive). Characters outside this range must be encoded using escape sequences (\b, \f, \n, \r, \t) or octal notation (e.g., \007). Single and double quotes can be escaped using a backslash, as can the backslash itself.

If endpoints are specified, they must be separated with a colon (:) and formatted as described in the endpoint syntax. The order of endpoints in the stringified proxy is not necessarily the order in which connections are attempted during binding: when a stringified proxy is converted into a proxy instance, by default, the endpoint list is randomized as a form of load balancing. You can change this default behavior using the properties Ice.Default.EndpointSelection and name.EndpointSelection.

If the -s option is specified, only those endpoints that support secure invocations are considered during binding. If no valid endpoints are found, the application receives Ice::NoEndpointException.

Otherwise, if the -s option is not specified, the endpoint list is ordered so that non-secure endpoints have priority over secure endpoints during binding. In other words, connections are attempted on all non-secure endpoints before any secure endpoints are attempted.

If an unknown option is specified, or the stringified proxy is malformed, the application receives Ice::ProxyParseException. If an endpoint is malformed, the application receives Ice::EndpointParseException.

Syntax for Stringified Endpoints

Synopsis

endpoint : endpoint

Description

An endpoint list comprises one or more endpoints separated by a colon (:).

An endpoint has the following format:

protocol option

The supported protocols are tcp, udp, ssl, and default. If default is used, it is replaced by the value of the Ice.Default.Protocol property. If an endpoint is malformed, or an unknown protocol is specified, the application receives Ice::EndpointParseException. The ssl protocol is only available if the IceSSL plug-in is installed.

Ice uses endpoints for two similar but distinct purposes:

1. In a client context (that is, in a proxy), endpoints determine how Ice establishes a connection to a server.
2. In a server context (that is, in an object adapter's configuration), endpoints define the addresses and transports over which new incoming connections are accepted. These endpoints are also embedded in the proxies created by the object adapter, unless a separate set of "published" endpoints are explicitly configured.

The sections that follow discuss the addressing component of endpoints, as well as the protocols and their supported options.

Address Syntax

Synopsis

host : hostname | x.x.x.x (IPv4)
host : hostname | ":x:x:x:x:x:x:x" (IPv6)

Description

Ice supports Internet Protocol (IP) versions 4 and 6 in all language mappings.

Support for these protocols is configured using the properties Ice.IPv4 (enabled by default) and Ice.IPv6 (disabled by default).

In the endpoint descriptions below, the host parameter represents either a host name that is resolved via the Domain Name System (DNS), an IPv4 address in dotted quad notation, or an IPv6 address in 128-bit hexadecimal format and enclosed in double quotes. Due to limitation of the DNS infrastructure, host and domain names are restricted to the ASCII character set.

The presence (or absence) of the host parameter has a significant influence on the behavior of the Ice run time. The table below describes these semantics:

There is one additional benefit in specifying a wildcard address for host (or not specifying it at all) in an object adapter's endpoint: if the list of network interfaces on a host may change while the application is running, using a wildcard address for host ensures that the object adapter automatically includes the updated interfaces. Note however that the list of published endpoints is not changed automatically; rather, the application must explicitly refresh the object adapter's endpoints. For diagnostic purposes, you can set the configuration property Ice.Trace.Network=3 to cause Ice to log the current list of local addresses that it is substituting for the wildcard address.

When IPv4 and IPv6 are enabled, an object adapter endpoint that uses an IPv6 (or wildcard) address can accept both IPv4 and IPv6 connections. This is true for all supported platforms except Windows XP and Windows Server 2003, where you must define separate IPv4 and IPv6 endpoints if you want the object adapter to accept both types of connections.

Java's default network stack always accepts both IPv4 and IPv6 connections regardless of the settings of Ice.IPv4 and Ice.IPv6. You can configure the Java run time to use only IPv4 by starting your application with the following JVM option:

{zcode:java}
java -Djava.net.preferIPv4Stack=true ...
{zcode}

TCP Endpoint Syntax

Synopsis

tcp -h host -p port -t timeout -z

Description

A tcp endpoint supports the following options:

UDP Endpoint Syntax

Synopsis

udp -v major.minor -e major.minor -h host -p port -z --ttl TTL --interface INTF

Description

A udp endpoint supports either unicast or multicast delivery; the address resolved by the host argument determines the delivery mode. To use multicast in IPv4, select an IP address in the range 233.0.0.0 to 239.255.255.255. With IPv6, use an address that begins with ff, such as ff01::1:1.

A udp endpoint supports the following options:

Multicast Interfaces

When host denotes a multicast address, the --interface INTF option selects a particular network interface to be used for communication. The format of INTF depends on the language and IP version:

• C++ and .NET (IPv4)
  INTF can be an interface name, such as eth0, or an IP address. Interface names on Windows may contain spaces, such as Local Area Connection, therefore they must be enclosed in double quotes.

• C++ and .NET (IPv6)
  INTF can be an interface name, such as eth0, or an interface index.

• Java
  INTF can be an interface name, such as eth0, or an IP address. On Windows, Java maps interface names to Unix-style nicknames.

  Ztop

SSL Endpoint Syntax

Synopsis

ssl -h host -p port -t timeout -z

Description

An ssl endpoint supports the following options:

Opaque Endpoint Syntax

Synopsis

opaque -t type -v value

Description

Proxies can contain endpoints that are not universally understood by Ice processes. For example, a proxy can contain an SSL endpoint; if that proxy is marshaled to a receiver without the IceSSL plug-in, the SSL endpoint does not make sense to the receiver.

Ice preserves such unknown endpoints when they are received over the wire. For the preceding example, if the receiver remarshals the proxy and sends it back to an Ice process that does have the IceSSL plug-in, that process can invoke on the proxy using its SSL transport. This mechanism allows proxies containing endpoints for arbitrary transports to pass through processes that do not understand these endpoints without losing information.

If an Ice process stringifies a proxy containing an unknown endpoint, it writes the endpoint as an opaque endpoint. For example:

{zcode}
opaque -t 2 -v CTEyNy4wLjAuMREnAAD/////AA==
{zcode}

This is how a process without the IceSSL plug-in stringifies an SSL endpoint. When a process with the IceSSL plug-in unstringifies this endpoint and converts it back into a string, it produces:

{zcode}
ssl -h 127.0.0.1 -p 10001
{zcode}

An opaque endpoint supports the following options:

Exactly one each of the -t and -v options must be present in an opaque endpoint.

See Also

• The Ice Protocol
• Object Adapter Endpoints
• Connection Timeouts