The Healthz service provides access to the status of a path on the
system. Addtitionally it allows the implementor to provide path specific
diagnositic data into the status return.

Healthz is expected to work in conjunction with the component OC model.

ArtifactTrailer is the last message in the artifact stream.

Generic proto message artifact stream.
This proto tells the caller that the artifact stream
will be a stream of proto encoded messages that make up
the artifact. Each message must be deserialized by the caller
and there are no other assumptions about the number of
messages or length of the stream or how those messages are to
be reassembled.

`Any` contains an arbitrary serialized protocol buffer message along with a
URL that describes the type of the serialized message.

Protobuf library provides support to pack/unpack Any values in the form
of utility functions or additional generated methods of the Any type.

Example 1: Pack and unpack a message in C++.

Foo foo = ...;
Any any;
any.PackFrom(foo);
...
if (any.UnpackTo(&foo)) {
...
}

Example 2: Pack and unpack a message in Java.

Foo foo = ...;
Any any = Any.pack(foo);
...
if (any.is(Foo.class)) {
foo = any.unpack(Foo.class);
}
// or ...
if (any.isSameTypeAs(Foo.getDefaultInstance())) {
foo = any.unpack(Foo.getDefaultInstance());
}

Example 3: Pack and unpack a message in Python.

foo = Foo(...)
any = Any()
any.Pack(foo)
...
if any.Is(Foo.DESCRIPTOR):
any.Unpack(foo)
...

Example 4: Pack and unpack a message in Go

foo := &pb.Foo{...}
any, err := anypb.New(foo)
if err != nil {
...
}
...
foo := &pb.Foo{}
if err := any.UnmarshalTo(foo); err != nil {
...
}

The pack methods provided by protobuf library will by default use
'type.googleapis.com/full.type.name' as the type URL and the unpack
methods only use the fully qualified type name after the last '/'
in the type URL, for example "foo.bar.com/x/y.z" will yield type
name "y.z".

JSON

The JSON representation of an `Any` value uses the regular
representation of the deserialized, embedded message, with an
additional field `@type` which contains the type URL. Example:

package google.profile;
message Person {
string first_name = 1;
string last_name = 2;
}

{
"@type": "type.googleapis.com/google.profile.Person",
"firstName": ,
"lastName":
}

If the embedded message type is well-known and has a custom JSON
representation, that representation will be embedded adding a field
`value` which holds the custom JSON in addition to the `@type`
field. Example (for message [google.protobuf.Duration][]):

{
"@type": "type.googleapis.com/google.protobuf.Duration",
"value": "1.212s"
}

A Timestamp represents a point in time independent of any time zone or local
calendar, encoded as a count of seconds and fractions of seconds at
nanosecond resolution. The count is relative to an epoch at UTC midnight on
January 1, 1970, in the proleptic Gregorian calendar which extends the
Gregorian calendar backwards to year one.

All minutes are 60 seconds long. Leap seconds are "smeared" so that no leap
second table is needed for interpretation, using a [24-hour linear
smear](https://developers.google.com/time/smear).

The range is from 0001-01-01T00:00:00Z to 9999-12-31T23:59:59.999999999Z. By
restricting to that range, we ensure that we can convert to and from [RFC
3339](https://www.ietf.org/rfc/rfc3339.txt) date strings.

# Examples

Example 1: Compute Timestamp from POSIX `time()`.

Timestamp timestamp;
timestamp.set_seconds(time(NULL));
timestamp.set_nanos(0);

Example 2: Compute Timestamp from POSIX `gettimeofday()`.

struct timeval tv;
gettimeofday(&tv, NULL);

Timestamp timestamp;
timestamp.set_seconds(tv.tv_sec);
timestamp.set_nanos(tv.tv_usec * 1000);

Example 3: Compute Timestamp from Win32 `GetSystemTimeAsFileTime()`.

FILETIME ft;
GetSystemTimeAsFileTime(&ft);
UINT64 ticks = (((UINT64)ft.dwHighDateTime) << 32) | ft.dwLowDateTime;

// A Windows tick is 100 nanoseconds. Windows epoch 1601-01-01T00:00:00Z
// is 11644473600 seconds before Unix epoch 1970-01-01T00:00:00Z.
Timestamp timestamp;
timestamp.set_seconds((INT64) ((ticks / 10000000) - 11644473600LL));
timestamp.set_nanos((INT32) ((ticks % 10000000) * 100));

Example 4: Compute Timestamp from Java `System.currentTimeMillis()`.

long millis = System.currentTimeMillis();

Timestamp timestamp = Timestamp.newBuilder().setSeconds(millis / 1000)
.setNanos((int) ((millis % 1000) * 1000000)).build();

Example 5: Compute Timestamp from Java `Instant.now()`.

Instant now = Instant.now();

Timestamp timestamp =
Timestamp.newBuilder().setSeconds(now.getEpochSecond())
.setNanos(now.getNano()).build();

Example 6: Compute Timestamp from current time in Python.

timestamp = Timestamp()
timestamp.GetCurrentTime()

# JSON Mapping

In JSON format, the Timestamp type is encoded as a string in the
[RFC 3339](https://www.ietf.org/rfc/rfc3339.txt) format. That is, the
format is "{year}-{month}-{day}T{hour}:{min}:{sec}[.{frac_sec}]Z"
where {year} is always expressed using four digits while {month}, {day},
{hour}, {min}, and {sec} are zero-padded to two digits each. The fractional
seconds, which can go up to 9 digits (i.e. up to 1 nanosecond resolution),
are optional. The "Z" suffix indicates the timezone ("UTC"); the timezone
is required. A proto3 JSON serializer should always use UTC (as indicated by
"Z") when printing the Timestamp type and a proto3 JSON parser should be
able to accept both UTC and other timezones (as indicated by an offset).

For example, "2017-01-15T01:30:15.01Z" encodes 15.01 seconds past
01:30 UTC on January 15, 2017.

In JavaScript, one can convert a Date object to this format using the
standard
[toISOString()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString)
method. In Python, a standard `datetime.datetime` object can be converted
to this format using
[`strftime`](https://docs.python.org/2/library/time.html#time.strftime) with
the time format spec '%Y-%m-%dT%H:%M:%S.%fZ'. Likewise, in Java, one can use
the Joda Time's [`ISODateTimeFormat.dateTime()`](
http://www.joda.org/joda-time/apidocs/org/joda/time/format/ISODateTimeFormat.html#dateTime%2D%2D
) to obtain a formatter capable of generating timestamps in this format.

Credentials defines credentials needed to perform authentication on a device.

HashType defines the valid hash methods for data verification. UNSPECIFIED
should be treated an error.

Path encodes a data tree path as a series of repeated strings, with
each element of the path representing a data tree node name and the
associated attributes.
Reference: gNMI Specification Section 2.2.2.

PathElem encodes an element of a gNMI path, along with any attributes (keys)
that may be associated with it.
Reference: gNMI Specification Section 2.2.2.

Generic Layer 3 Protocol enumeration.

The gNOI service semantic version.