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Syntax for Stringified Proxies
Synopsis
identity -f facet -e encoding -p protocol -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 is a well-known proxy; a proxy with an identity and an object adapter identifier represents an indirect proxy that will be resolved using the Ice locator.
Proxy options configure the invocation mode:
| Select a facet of the Ice object. |
| Specify the Ice encoding version to use when an invocation on this proxy marshals parameters. |
| Specify the Ice protocol version to use when sending a request with this proxy. |
| Configures the proxy for twoway invocations (default). |
| Configures the proxy for oneway invocations. |
| Configures the proxy for batch oneway invocations. |
| Configures the proxy for datagram invocations. |
| Configures the proxy for batch datagram invocations. |
| Configures the proxy for secure invocations. |
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 strings that are encoded as described in Object Identity, in particular, 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 string encoded like a Slice String Literal.
Likewise, an object adapter identifier adapter_id is a string encoded like a Slice String Literal. 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 as an opening or closing quote, for example:
"a string with a ' quote"
Single quotes prevent interpretation of a double quote as an opening or closing quote. For example:
'a string with a " quote'
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.
The -e and -p options specify the encoding and protocol versions supported by the target object, respectively. The Ice run time in the client is responsible for using a compatible version of the encoding or protocol, where compatible means the same major version and a minor version that is equal to or less than the specified minor version. If the -e option is not defined, the proxy uses the default version specified by Ice.Default.EncodingVersion.
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, ws, wss, 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 and wss protocols are only available if the IceSSL plug-in is installed.
Ice uses endpoints for two similar but distinct purposes:
- In a client context (that is, in a proxy), endpoints determine how Ice establishes a connection to a server.
- 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.
See Object Adapter Endpoints for examples.
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 and Ice.IPv6 (both enabled 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:
Value | Client Semantics | Server Semantics |
|---|---|---|
None | If | If |
Host name | The host name is resolved via DNS. Outgoing connections are attempted to each address returned by the DNS query. | The host name is resolved via DNS, and the object adapter listens on the network interfaces corresponding to each address returned by the DNS query. The specified host name is embedded in proxies created by the adapter if the endpoint specifies a fixed port. Otherwise, if the port is selected by the operating system, proxies will embed an endpoint for each address and the system allocated port. |
IPv4 address | An outgoing connection is attempted to the given address. | The object adapter listens on the network interface corresponding to the address. The specified address is embedded in proxies created by the adapter. |
IPv6 address | An outgoing connection is attempted to the given address. | The object adapter listens on the network interface corresponding to the address. The specified address is embedded in proxies created by the adapter. |
| A "wildcard" IPv4 address that causes Ice to try all local interfaces when establishing an outgoing connection. | The adapter listens on all IPv4 network interfaces (including the loopback interface), that is, binds to INADDR_ANY for IPv4. Endpoints for all addresses except loopback are published in proxies (unless loopback is the only available interface, in which case only loopback is published). |
| A "wildcard" IPv6 address that causes Ice to try all local interfaces when establishing an outgoing connection. | Equivalent to * (see below). |
| Not supported in proxies. | The adapter listens on all network interfaces (including the loopback interface), that is, binds to INADDR_ANY for the enabled protocols (IPv4 and/or IPv6). Endpoints for all addresses except loopback and IPv6 link-local are published in proxies (unless loopback is the only available interface, in which case only loopback is published). |
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.
Java's default network stack always accepts both IPv4 and IPv6 connections regardless of the settings of Ice.IPv6. Thus, in Java, an object adapter endpoint that uses the IPv4 wildcard will accept both IPv4 and IPv6 connections. You can configure the Java run time to use only IPv4 by starting your application with the following JVM option:
java -Djava.net.preferIPv4Stack=true ...
TCP Endpoint Syntax
Synopsis
tcp -h host -p port -t timeout -z --sourceAddress addr
Availability
The TCP transport is a built-in transport, it's always available.
Description
A tcp endpoint supports the following options:
Option | Description | Client Semantics | Server Semantics |
|---|---|---|---|
| Specifies the host name or IP address of the endpoint. If not specified, the value of | See Address Syntax. | See Address Syntax. |
| Specifies the port number of the endpoint. | Determines the port to which a connection attempt is made (required). | The port will be selected by the operating system if this option is not specified or |
| Specifies the endpoint timeout in milliseconds. | The value for | The value for |
| Specifies bzip2 compression. | Determines whether compressed requests are sent. | Determines whether compression is advertised in proxies created by the adapter. |
| Specifies the source address used by the connection. | The value for This option allows to specify the source address set in the IP packet. It doesn't necessarily imply that the operating system will use the network interface matching this IP address to send out the IP packet. This feature is not supported on Universal Windows (UWP). | Not supported |
UDP Endpoint Syntax
Synopsis
udp -h host -p port -z --ttl TTL --interface INTF --sourceAddress addr
Availability
The UDP transport is a built-in transport except for C++ and Objective-C static builds where it's only available to programs that explicitly register the UDP plug-in. See Using Plugins with Static Libraries.
Description
A udp endpoint supports either unicast or multicast delivery; the address resolved by 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. In IPv6, use an address that begins with ff, such as ff01::1:1.
A udp endpoint supports the following options:
Option | Description | Client Semantics | Server Semantics |
|---|---|---|---|
| Specifies the host name or IP address of the endpoint. If not specified, the value of | See Address Syntax. | See Address Syntax. |
| Specifies the port number of the endpoint. | Determines the port to which datagrams are sent (required). | The port will be selected by the operating system if this option is not specified or port is zero. |
| Specifies bzip2 compression. | Determines whether compressed requests are sent. | Determines whether compression is advertised in proxies created by the adapter. |
| Specifies the time-to-live (also known as "hops") of multicast messages. | Determines whether multicast messages are forwarded beyond the local network. If not specified, or the value of | N/A |
| Specifies the network interface or group for multicast messages (see below). | Selects the network interface for outgoing multicast messages. If not specified, multicast messages are sent using the default interface. | Selects the network interface to use when joining the multicast group. If set to * or not specified, the group is joined on all the local network interfaces. |
| Binds outgoing socket connections to the network interface associated with | The value for This option allows to specify the source address set in the IP packet. It doesn't necessarily imply that the operating system will use the network interface matching this IP address to send out the IP packet. This feature is not supported on Universal Windows (UWP). | Not supported |
Deprecated options
With the 1.0 encoding, UDP endpoints supported 2 additional options: the -e major.minor and -v major.minor options. These 2 options specified which encoding and protocol was supported by the endpoint. These two options are deprecated with the 1.1 encoding and are ignored (a deprecation warning will be emitted when parsed by the communicator stringToProxy method). The supported protocol and encoding is specified on the proxy with the 1.1 encoding.
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
INTFcan be an interface name, such aseth0, or an IP address. If using IPv6, it can also be an interface index. Interface names on Windows may contain spaces, such asLocal Area Connection, therefore they must be enclosed in double quotes.
- Java
INTFcan be an interface name, such aseth0, or an IP address. On Windows, Java maps interface names to Unix-style nicknames.
SSL Endpoint Syntax
Synopsis
ssl -h host -p port -t timeout -z --sourceAddress addr
Availability
The SSL transport is provided by a separate IceSSL plug-in.
Description
An ssl endpoint supports the same options as for tcp endpoints.
WS Endpoint Syntax
Synopsis
ws -r resource -h host -p port -t timeout -z --sourceAddress addr
Availability
The WS transport is a built-in transport except for C++ and Objective-C static builds where it's only available to programs that explicitly register the WS plug-in. See Using Plugins with Static Libraries.
Description
A ws (WebSocket) endpoint supports all tcp endpoint options in addition to the following:
Option | Description | Client Semantics | Server Semantics |
|---|---|---|---|
| A URI specifying the resource associated with this endpoint. If not specified, the default value is | The value for | The web server configuration must direct the given |
WSS Endpoint Syntax
Synopsis
wss -r resource -h host -p port -t timeout -z --sourceAddress addr
Availability
The WSS transport is a built-in transport and only enabled if an SSL transport is configured with the communicator. Like for the WS transport, the WS plug-in needs to be registered explicitly for C++ and Objective-C static builds. See Using Plugins with Static Libraries.
Description
A wss (Secure WebSocket) endpoint supports all ssl endpoint options in addition to the following:
Option | Description | Client Semantics | Server Semantics |
|---|---|---|---|
| A URI specifying the resource associated with this endpoint. If not specified, the default value is | The value for | The web server configuration must direct the given |
Bluetooth Endpoint Syntax
Synopsis
bt -a addr -u uuid -c channel -t timeout -z --name name
bts -a addr -u uuid -c channel -t timeout -z --name name
Availability
The Bluetooth transport is provided by a separate IceBT plug-in.
Description
Support for Bluetooth endpoints is provided by the IceBT transport plug-in. The plug-in enables the bt protocol by default; if the IceSSL transport plug-in is also installed, IceBT enables the bts protocol as well. A Bluetooth endpoint supports the following options:
Option | Description | Client Semantics | Server Semantics |
|---|---|---|---|
| Specifies the Bluetooth device address in the form | An address is required for proxy endpoints. The plug-in will throw | On Linux, the plug-in uses the address to select the Bluetooth adapter on which to listen for new connections. If no address is specified via the On Android, the plug-in ignores this setting and always uses the system's default adapter. In addition to a Bluetooth device address, |
-u uuid | Specifies the UUID of a service. | A UUID is required for proxy endpoints. The plug-in uses the UUID to search for a matching service at the specified device address. | A UUID is optional (but recommended) for object adapter endpoints. If this option is not specified, the plug-in generates a random UUID. The plug-in registers the service with its UUID in the local SDP registry so that clients can locate it. |
| Specifies the RFCOMM channel number of the endpoint. | Not supported in proxy endpoints – the plug-in always uses the service UUID to connect to a server. | This setting is optional on Linux. The value for This setting is ignored on Android – the system always selects the channel. |
| Specifies the endpoint timeout in milliseconds. | The value for | The value for |
| Specifies bzip2 compression. | Determines whether compressed requests are sent. | Determines whether compression is advertised in proxies created by the adapter. |
| Specifies the service name. | Ignored in proxy endpoints. | Associates a human-friendly name with the service's entry in the SDP registry. If not specified, the default name is |
Opaque Endpoint Syntax
Synopsis
opaque -t type -e encoding -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:
opaque -t 2 -e 1.0 -v CTEyNy4wLjAuMREnAAD/////AA==
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:
ssl -h 127.0.0.1 -p 10001
An opaque endpoint supports the following options:
Option | Description |
|---|---|
| Specifies the transport for the endpoint. Transports are indicated by positive integers (1 for TCP, 2 for SSL, and 3 for UDP). |
-e encoding | Specifies the encoding version used to encode the endpoint marshaled data. |
| Specifies the marshaled encoding of the endpoint in base-64 encoding. |
Exactly one each of the -t and -v options must be present in an opaque endpoint. If -e is not specified, the current encoding supported by the Ice runtime is assumed.