See also KIP-183.
This implements the following algorithm:
AdminClient sends ElectPreferredLeadersRequest.
KafakApis receives ElectPreferredLeadersRequest and delegates to
ReplicaManager.electPreferredLeaders()
ReplicaManager delegates to KafkaController.electPreferredLeaders()
KafkaController adds a PreferredReplicaLeaderElection to the EventManager,
ReplicaManager.electPreferredLeaders()'s callback uses the
delayedElectPreferredReplicasPurgatory to wait for the results of the
election to appear in the metadata cache. If there are no results
because of errors, or because the preferred leaders are already leading
the partitions then a response is returned immediately.
In the EventManager work thread the preferred leader is elected as follows:
The EventManager runs PreferredReplicaLeaderElection.process()
process() calls KafkaController.onPreferredReplicaElectionWithResults()
KafkaController.onPreferredReplicaElectionWithResults()
calls the PartitionStateMachine.handleStateChangesWithResults() to
perform the election (asynchronously the PSM will send LeaderAndIsrRequest
to the new and old leaders and UpdateMetadataRequest to all brokers)
then invokes the callback.
Reviewers: Colin P. McCabe <cmccabe@apache.org>, Jun Rao <junrao@gmail.com>
* Allow the Trogdor agent to be started in "exec mode", where it simply
runs a single task and exits after it is complete.
* For AgentClient and CoordinatorClient, allow the user to pass the path
to a file containing JSON, instead of specifying the JSON object in the
command-line text itself. This means that we can get rid of the bash
scripts whose only function was to load task specs into a bash string
and run a Trogdor command.
* Print dates and times in a human-readable way, rather than as numbers
of milliseconds.
* When listing tasks or workers, output human-readable tables of
information.
* Allow the user to filter on task ID name, task ID pattern, or task
state.
* Support a --json flag to provide raw JSON output if desired.
Reviewed-by: David Arthur <mumrah@gmail.com>, Stanislav Kozlovski <stanislav_kozlovski@outlook.com>
Expose a programmatic way to bring up a Kafka and Zk cluster through Java API to facilitate integration tests for framework level changes in Kafka Connect. The Kafka classes would be similar to KafkaEmbedded in streams. The new classes would reuse the kafka.server.KafkaServer classes from :core, and provide a simple interface to bring up brokers in integration tests.
Signed-off-by: Arjun Satish <arjunconfluent.io>
Author: Arjun Satish <arjun@confluent.io>
Author: Arjun Satish <wicknicks@users.noreply.github.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5516 from wicknicks/connect-integration-test
Reviewers: Bill Bejeck <bill@confluent.io>, John Roesler <john@confluent.io>, Guozhang Wang <guozhang@confluent.io>, Ryanne Dolan <ryannedolan@gmail.com>, Ismael Juma <ismael@confuent.io>
This patch adds a framework to automatically generate the request/response classes for Kafka's protocol. The code will be updated to use the generated classes in follow-up patches. Below is a brief summary of the included components:
**buildSrc/src**
The message generator code is here. This code is automatically re-run by gradle when one of the schema files changes. The entire directory is processed at once to minimize the number of times we have to start a new JVM. We use Jackson to translate the JSON files into Java objects.
**clients/src/main/java/org/apache/kafka/common/protocol/Message.java**
This is the interface implemented by all automatically generated messages.
**clients/src/main/java/org/apache/kafka/common/protocol/MessageUtil.java**
Some utility functions used by the generated message code.
**clients/src/main/java/org/apache/kafka/common/protocol/Readable.java, Writable.java, ByteBufferAccessor.java**
The generated message code uses these classes for writing to a buffer.
**clients/src/main/message/README.md**
This README file explains how the JSON schemas work.
**clients/src/main/message/\*.json**
The JSON files in this directory implement every supported version of every Kafka API. The unit tests automatically validate that the generated schemas match the hand-written schemas in our code. Additionally, there are some things like request and response headers that have schemas here.
**clients/src/main/java/org/apache/kafka/common/utils/ImplicitLinkedHashSet.java**
I added an optimization here for empty sets. This is useful here because I want all messages to start with empty sets by default prior to being loaded with data. This is similar to the "empty list" optimizations in the `java.util.ArrayList` class.
Reviewers: Stanislav Kozlovski <stanislav_kozlovski@outlook.com>, Ismael Juma <ismael@juma.me.uk>, Bob Barrett <bob.barrett@outlook.com>, Jason Gustafson <jason@confluent.io>
KIP-368 implementation to enable periodic re-authentication of SASL clients. Also adds a broker configuration option to terminate client connections that do not re-authenticate within the configured interval.
Add CreatePartitionsRequest.PartitionDetails similar to CreateTopicsRequest.TopicDetails to avoid references from `common.requests` package to `clients`.
Reviewers: Ismael Juma <ismael@juma.me.uk>
Development of EasyMock and PowerMock has stagnated while Mockito
continues to be actively developed. With the new Java release cadence,
it's a problem to depend on libraries that do bytecode manipulation
and are not actively maintained. In addition, Mockito is also
easier to use.
While updating the tests, I attempted to go from failing test to
passing test. In cases where the updated test passed on the first
attempt, I artificially broke it to ensure the test was still doing its
job.
I included a few improvements that were helpful while making these
changes:
1. Better exception if there are no nodes in `leastLoadedNodes`
2. Always close the producer in `KafkaProducerTest`
3. requestsInFlight producer metric should not hold a reference to
`Sender`
Finally, `Metadata` is no longer final so that we don't need
`PowerMock` to mock it. It's an internal class, so it's OK.
Author: Ismael Juma <ismael@juma.me.uk>
Reviewers: Viktor Somogyi <viktorsomogyi@gmail.com>, Dong Lin <lindong28@gmail.com>
Closes#5691 from ijuma/kafka-7438-mockito
Modified several classes' `equals` methods and simplified a complex method to
reduce the NPath complexity so they could be removed from the checkstyle
suppressions that were required with the recent move to Java 8 and upgrade
of Checkstyle: https://github.com/apache/kafka/pull/5046.
Reviewers: Robert Yokota <rayokota@gmail.com>, Arjun Satish <arjun@confluent.io>, Ismael Juma <ismael@juma.me.uk>
A call to `kafka-consumer-groups --describe --group ...` can result in NullPointerException for two reasons:
1) `Fetcher.fetchOffsetsByTimes()` may return too early, without sending list offsets request for topic partitions that are not in cached metadata.
2) `ConsumerGroupCommand.getLogEndOffsets()` and `getLogStartOffsets()` assumed that endOffsets()/beginningOffsets() which eventually call Fetcher.fetchOffsetsByTimes(), would return a map with all the topic partitions passed to endOffsets()/beginningOffsets() and that values are not null. Because of (1), null values were possible if some of the topic partitions were already known (in metadata cache) and some not (metadata cache did not have entries for some of the topic partitions). However, even with fixing (1), endOffsets()/beginningOffsets() may return a map with some topic partitions missing, when list offset request returns a non-retriable error. This happens in corner cases such as message format on broker is before 0.10, or maybe in cases of some other errors.
Testing:
-- added unit test to verify fix in Fetcher.fetchOffsetsByTimes()
-- did some manual testing with `kafka-consumer-groups --describe`, causing NPE. Was not able to reproduce any NPE cases with DescribeConsumerGroupTest.scala,
Reviewers: Jason Gustafson <jason@confluent.io>
Previously, we depicted creating a Jackson serde for every pojo class, which becomes a burden in practice. There are many ways to avoid this and just have a single serde, so we've decided to model this design choice instead.
Reviewers: Viktor Somogyi <viktorsomogyi@gmail.com>, Bill Bejeck <bill@confluent.io>, Guozhang Wang <wangguoz@gmail.com>
Relative paths in Gradle break when the Gradle daemon is used
unless user.dir can be changed while the process is running.
Java 11 disallows this, so we use project paths instead.
Verified that rat and checkstyle work with Java 11 after these
changes.
Reviewers: Dong Lin <lindong28@gmail.com>
We need to use the same lock for metric update and read to avoid NPE and concurrent modification exceptions. Sensor add/remove/update are synchronized on Sensor since they access lists and maps that are not thread-safe. Reporters are notified of metrics add/remove while holding (Sensor, Metrics) locks and reporters may synchronize on the reporter lock. Metric read may be invoked by metrics reporters while holding a reporter lock. So read/update cannot be synchronized using Sensor since that could lead to deadlock. This PR introduces a new lock in Sensor for update/read.
Locking order:
- Sensor#add: Sensor -> Metrics -> MetricsReporter
- Metrics#removeSensor: Sensor -> Metrics -> MetricsReporter
- KafkaMetric#metricValue: MetricsReporter -> Sensor#metricLock
- Sensor#record: Sensor -> Sensor#metricLock
Reviewers: Jun Rao <junrao@gmail.com>, Guozhang Wang <wangguoz@gmail.com>
- Removed Scala consumers (`SimpleConsumer` and `ZooKeeperConsumerConnector`)
and their tests.
- Removed Scala request/response/message classes.
- Removed any mention of new consumer or new producer in the code
with the exception of MirrorMaker where the new.consumer option was
never deprecated so we have to keep it for now. The non-code
documentation has not been updated either, that will be done
separately.
- Removed a number of tools that only made sense in the context
of the Scala consumers (see upgrade notes).
- Updated some tools that worked with both Scala and Java consumers
so that they only support the latter (see upgrade notes).
- Removed `BaseConsumer` and related classes apart from `BaseRecord`
which is used in `MirrorMakerMessageHandler`. The latter is a pluggable
interface so effectively public API.
- Removed `ZkUtils` methods that were only used by the old consumers.
- Removed `ZkUtils.registerBroker` and `ZKCheckedEphemeral` since
the broker now uses the methods in `KafkaZkClient` and no-one else
should be using that method.
- Updated system tests so that they don't use the Scala consumers except
for multi-version tests.
- Updated LogDirFailureTest so that the consumer offsets topic would
continue to be available after all the failures. This was necessary for it
to work with the Java consumer.
- Some multi-version system tests had not been updated to include
recently released Kafka versions, fixed it.
- Updated findBugs and checkstyle configs not to refer to deleted
classes and packages.
Reviewers: Dong Lin <lindong28@gmail.com>, Manikumar Reddy <manikumar.reddy@gmail.com>
Reviewers: Colin Patrick McCabe <colin@cmccabe.xyz>, Jun Rao <junrao@gmail.com>
Co-authored-by: Piyush Vijay <pvijay@apple.com>
Co-authored-by: Andy Coates <big-andy-coates@users.noreply.github.com>
This commit allows secrets in Connect configs to be externalized and replaced with variable references of the form `${provider:[path:]key}`, where the "path" is optional.
There are 2 main additions to `org.apache.kafka.common.config`: a `ConfigProvider` and a `ConfigTransformer`. The `ConfigProvider` is an interface that allows key-value pairs to be provided by an external source for a given "path". An a TTL can be associated with the key-value pairs returned from the path. The `ConfigTransformer` will use instances of `ConfigProvider` to replace variable references in a set of configuration values.
In the Connect framework, `ConfigProvider` classes can be specified in the worker config, and then variable references can be used in the connector config. In addition, the herder can be configured to restart connectors (or not) based on the TTL returned from a `ConfigProvider`. The main class that performs restarts and transformations is `WorkerConfigTransformer`.
Finally, a `configs()` method has been added to both `SourceTaskContext` and `SinkTaskContext`. This allows connectors to get configs with variables replaced by the latest values from instances of `ConfigProvider`.
Most of the other changes in the Connect framework are threading various objects through classes to enable the above functionality.
Author: Robert Yokota <rayokota@gmail.com>
Author: Ewen Cheslack-Postava <me@ewencp.org>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5068 from rayokota/KAFKA-6886-connect-secrets
This PR provides the implementation for KIP-285 and also a reference implementation for authenticating BasicAuth credentials using JAAS LoginModule
Author: Magesh Nandakumar <magesh.n.kumar@gmail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Arjun Satish <wicknicks@users.noreply.github.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4931 from mageshn/KIP-285
This KIP adds the following functionality related to SASL/OAUTHBEARER:
1) Allow clients (both brokers when SASL/OAUTHBEARER is the inter-broker protocol as well as non-broker clients) to flexibly retrieve an access token from an OAuth 2 authorization server based on the declaration of a custom login CallbackHandler implementation and have that access token transparently and automatically transmitted to a broker for authentication.
2) Allow brokers to flexibly validate provided access tokens when a client establishes a connection based on the declaration of a custom SASL Server CallbackHandler implementation.
3) Provide implementations of the above retrieval and validation features based on an unsecured JSON Web Token that function out-of-the-box with minimal configuration required (i.e. implementations of the two types of callback handlers mentioned above will be used by default with no need to explicitly declare them).
4) Allow clients (both brokers when SASL/OAUTHBEARER is the inter-broker protocol as well as non-broker clients) to transparently retrieve a new access token in the background before the existing access token expires in case the client has to open new connections.
* Set --source, --target and --release to 1.8.
* Build Scala 2.12 by default.
* Remove some conditionals in the build file now that Java 8
is the minimum version.
* Bump the version of Jetty, Jersey and Checkstyle (the newer
versions require Java 8).
* Fixed issues uncovered by the new version if Checkstyle.
* A couple of minor updates to handle an incompatible source
change in the new version of Jetty.
* Add dependency to jersey-hk2 to fix failing tests caused
by Jersey upgrade.
* Update release script to use Java 8 and to take into account
that Scala 2.12 is now built by default.
* While we're at it, bump the version of Gradle, Gradle plugins,
ScalaLogging, JMH and apache directory api.
* Minor documentation updates including the readme and upgrade
notes. A number of Streams Java 7 examples can be removed
subsequently.
* unify skipped records metering
* log warnings when things get skipped
* tighten up metrics usage a bit
### Testing strategy:
Unit testing of the metrics and the logs should be sufficient.
Author: John Roesler <john@confluent.io>
Reviewers: Bill Bejeck <bill@confluent.io>, Matthias J. Sax <matthias@confluent.io>, Guozhang Wang <wangguoz@gmail.com>
Closes#4812 from vvcephei/kip-274-streams-skip-metrics
Implement destroying tasks and workers. This means erasing all record of them on the Coordinator and the Agent.
Workers should be identified by unique 64-bit worker IDs, rather than by the names of the tasks they are implementing. This ensures that when a task is destroyed and re-created with the same task ID, the old workers will be not be treated as part of the new task instance.
Fix some return results from RPCs. In some cases RPCs were returning values that were never used. Attempting to re-create the same task ID with different arguments should fail. Add RequestConflictException to represent HTTP error code 409 (CONFLICT) for this scenario.
If only one worker in a task stops, don't stop all the other workers for that task, unless the worker that stopped had an error.
Reviewers: Anna Povzner <anna@confluent.io>, Rajini Sivaram <rajinisivaram@googlemail.com>
Added configs to ProducerBenchSpec:
topicPrefix: name of topics will be of format topicPrefix + topic index. If not provided, default is "produceBenchTopic".
partitionsPerTopic: number of partitions per topic. If not provided, default is 1.
replicationFactor: replication factor per topic. If not provided, default is 3.
The behavior of producer bench is changed such that if some or all topics already exist (with topic names = topicPrefix + topic index), and they have the same number of partitions as requested, the worker uses those topics and does not fail. The producer bench fails if one or more existing topics has number of partitions that is different from expected number of partitions.
Added unit test for WorkerUtils -- for existing methods and new methods.
Fixed bug in MockAdminClient, where createTopics() would over-write existing topic's replication factor and number of partitions while correctly completing the appropriate futures exceptionally with TopicExistsException.
Reviewers: Colin P. Mccabe <cmccabe@confluent.io>, Rajini Sivaram <rajinisivaram@googlemail.com>
This is a straight-forward change that make the name of the partition assignor to be aligned with Streams.
Reviewers: Matthias J. Sax <mjsax@apache.org>
Submitting a fail safe fix for rare IOExceptions on symbolic links.
The fix is submitted without a test case since it does seem easy to reproduce such type of failures (just having a broken symbolic link does not reproduce the issue) and it's considered pretty low risk.
If accepted, needs to be ported at least to 1.0, if not 0.11
Author: Konstantine Karantasis <konstantine@confluent.io>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4481 from kkonstantine/KAFKA-6288-Broken-symlink-interrupts-scanning-the-plugin-path
Dynamic update of listeners as described in KIP-226. This includes:
- Addition of new listeners with listener-prefixed security configs
- Removal of existing listeners
- Password encryption
- sasl.jaas.config property for broker's JAAS config prefixed with listener and mechanism name
**[KIP-145](https://cwiki.apache.org/confluence/display/KAFKA/KIP-145+-+Expose+Record+Headers+in+Kafka+Connect) has been accepted, and this PR implements KIP-145 except without the SMTs.**
Changed the Connect API and runtime to support message headers as described in [KIP-145](https://cwiki.apache.org/confluence/display/KAFKA/KIP-145+-+Expose+Record+Headers+in+Kafka+Connect).
The new `Header` interface defines an immutable representation of a Kafka header (key-value pair) with support for the Connect value types and schemas. This interface provides methods for easily converting between many of the built-in primitive, structured, and logical data types.
The new `Headers` interface defines an ordered collection of headers and is used to track all headers associated with a `ConnectRecord` (and thus `SourceRecord` and `SinkRecord`). This does allow multiple headers with the same key. The `Headers` contains methods for adding, removing, finding, and modifying headers. Convenience methods allow connectors and transforms to easily use and modify the headers for a record.
A new `HeaderConverter` interface is also defined to enable the Connect runtime framework to be able to serialize and deserialize headers between the in-memory representation and Kafka’s byte[] representation. A new `SimpleHeaderConverter` implementation has been added, and this serializes to strings and deserializes by inferring the schemas (`Struct` header values are serialized without the schemas, so they can only be deserialized as `Map` instances without a schema.) The `StringConverter`, `JsonConverter`, and `ByteArrayConverter` have all been extended to also be `HeaderConverter` implementations. Each connector can be configured with a different header converter, although by default the `SimpleHeaderConverter` is used to serialize header values as strings without schemas.
Unit and integration tests are added for `ConnectHeader` and `ConnectHeaders`, the two implementation classes for headers. Additional test methods are added for the methods added to the `Converter` implementations. Finally, the `ConnectRecord` object is already used heavily, so only limited tests need to be added while quite a few of the existing tests already cover the changes.
Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Arjun Satish <arjun@confluent.io>, Ted Yu <yuzhihong@gmail.com>, Magesh Nandakumar <magesh.n.kumar@gmail.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4319 from rhauch/kafka-5142-b
* KAFKA-3625: Add public test utils for Kafka Streams
- add new artifact test-utils
- add TopologyTestDriver
- add MockTime, TestRecord, add TestRecordFactory
Reviewers: Guozhang Wang <wangguoz@gmail.com>, Damian Guy <damian.guy@gmail.com>, Bill Bejeck <bill@confluent.io>
Enable dynamic broker configuration (see KIP-226 for details). Includes
- Base implementation to allow specific broker configs and custom configs to be dynamically updated
- Extend DescribeConfigsRequest/Response to return all synonym configs and their sources in the order of precedence
- Extend AdminClient to alter dynamic broker configs
- Dynamic update of SSL keystores
Reviewers: Ted Yu <yuzhihong@gmail.com>, Jason Gustafson <jason@confluent.io>
- Add capability to create delegation token
- Add authentication based on delegation token.
- Add capability to renew/expire delegation tokens.
- Add units tests and integration tests
Author: Manikumar Reddy <manikumar.reddy@gmail.com>
Reviewers: Jun Rao <junrao@gmail.com>
Closes#3616 from omkreddy/KAFKA-4541
* Use KafkaZkClient in ReassignPartitionsCommand
* Use KafkaZkClient in PreferredReplicaLeaderElectionCommand
* Updated test classes to use new methods
* All existing tests should pass
Author: Manikumar Reddy <manikumar.reddy@gmail.com>
Reviewers: Jun Rao <junrao@gmail.com>
Closes#4260 from omkreddy/KAFKA-5647-ADMINCOMMANDS
Author: Matthias J. Sax <matthias@confluent.io>
Reviewers: Ismael Juma <ismael@juma.me.uk>, Bill Bejeck <bbejeck@gmail.com>, Guozhang Wang <wangguoz@gmail.com>
Closes#4242 from mjsax/kafka-4857-admit-client
For ducktape: add Kibosh to the testing Dockerfile.
Create files_unreadable_fault_spec.py.
For trogdor: create FilesUnreadableFaultSpec.java.
Add a unit test of using the Kibosh service.
Author: Colin P. Mccabe <cmccabe@confluent.io>
Reviewers: Rajini Sivaram <rajinisivaram@googlemail.com>
Closes#4195 from cmccabe/KAFKA-5811
Previously, Trogdor only handled "Faults." Now, Trogdor can handle
"Tasks" which may be either faults, or workloads to execute in the
background.
The Agent and Coordinator have been refactored from a
mutexes-and-condition-variables paradigm into a message passing
paradigm. No locks are necessary, because only one thread can access
the task state or worker state. This makes them a lot easier to reason
about.
The MockTime class can now handle mocking deferred message passing
(adding a message to an ExecutorService with a delay). I added a
MockTimeTest.
MiniTrogdorCluster now starts up Agent and Coordinator classes in
paralle in order to minimize junit test time.
RPC messages now inherit from a common Message.java class. This class
handles implementing serialization, equals, hashCode, etc.
Remove FaultSet, since it is no longer necessary.
Previously, if CoordinatorClient or AgentClient hit a networking
problem, they would throw an exception. They now retry several times
before giving up. Additionally, the REST RPCs to the Coordinator and
Agent have been changed to be idempotent. If a response is lost, and
the request is resent, no harm will be done.
Author: Colin P. Mccabe <cmccabe@confluent.io>
Reviewers: Rajini Sivaram <rajinisivaram@googlemail.com>, Ismael Juma <ismael@juma.me.uk>
Closes#4073 from cmccabe/KAFKA-6060
A new mechanism was added recently to the Metrics framework to make it easier to generate the documentation. It uses a registry with a MetricsNameTemplate for each metric, and then those templates are used when creating the actual metrics. The metrics framework provides utilities that can generate the HTML documentation from the registry of templates.
This change moves the recently-added Connect metrics over to use these templates and to then generate the metric documentation for Connect.
This PR is based upon #3975 and can be rebased once that has been merged.
Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>
Closes#3987 from rhauch/kafka-5990
Adds new metrics to support health checks:
1. Error rates for each request type, per-error code
2. Request size and temporary memory size
3. Message conversion rate and time
4. Successful and failed authentication rates
5. ZooKeeper latency and status
6. Client version
Author: Rajini Sivaram <rajinisivaram@googlemail.com>
Reviewers: Ismael Juma <ismael@juma.me.uk>
Closes#3705 from rajinisivaram/KAFKA-5746-new-metrics
1. Raise AuthenticationException for authentication failures in admin client
2. Handle AuthenticationException as a fatal error for transactional producer
3. Add comments to authentication exceptions
Author: Rajini Sivaram <rajinisivaram@googlemail.com>
Reviewers: Vahid Hashemian <vahidhashemian@us.ibm.com>, Ismael Juma <ismael@juma.me.uk>
Closes#3928 from rajinisivaram/KAFKA-5947-auth-failure
This refactor achieves the following:
1. Breaks up the increasingly unmanageable `Protocol` class and moves schemas closer to their actual usage.
2. Removes the need for redundant field identifiers maintained separately in `Protocol` and the respective request/response objects.
3. Provides a better mechanism for sharing common fields between different schemas (e.g. topics, partitions, error codes, etc.).
4. Adds convenience helpers to `Struct` for common patterns (such as setting a field only if it exists).
Author: Jason Gustafson <jason@confluent.io>
Reviewers: Ismael Juma <ismael@juma.me.uk>
Closes#3813 from hachikuji/protocol-schema-refactor
Tom Bentley
Colin Patrick McCabe
Arjun Satish
Arjun Satish
Matthias J. Sax
Stanislav Kozlovski
Ron Dagostino
Rajini Sivaram
Ismael Juma
Randall Hauch
Anna Povzner
John Roesler
Manikumar Reddy O
Joan Goyeau
Andy Coates
Robert Yokota
Magesh Nandakumar
John Roesler
Jorge Quilcate Otoya
Guozhang Wang
Konstantine Karantasis
Matthias J. Sax
Colin P. Mccabe
Bill Bejeck
Jason Gustafson