Hi Amareshwari, I am able to resolve the impersonation issue by disabling the feature in HiveServer2:
<property> <name>hive.server2.enable.doAs</name> <value>false</value> <description>Set this property to enable impersonation in Hive Server 2</description> </property> Thanks, On Mon, Aug 1, 2016 at 9:24 PM, amareshwarisr . <[email protected]> wrote: > For #1, the solution is to add the proxyuser groups and hosts as you have > done in #2. And I don't know of any other way to avoid proxy user > configuration from hadoop. > > For #4 - Lens submits to HiveServer2 over thrift, not through jdbc. > > > > On Tue, Aug 2, 2016 at 12:28 AM, Tao Yan <[email protected]> wrote: > >> Hi Amareshwari, >> >> 1. I tried restarting lensserver with --classpath /etc/hadoop/conf and >> in the mapred-site.xml removed the problematic property, then, it throws a >> different error: >> >> >> INFO org.apache.hadoop.hive.ql.exec.Utilities - >> BytesPerReducer=1000000000 maxReducers=999 totalInputFileSize=248 >> INFO org.apache.hadoop.hive.ql.exec.Task - Number of reduce tasks not >> specified. Estimated from input data size: 1 >> INFO org.apache.hadoop.hive.ql.exec.Task - In order to change the >> average load for a reducer (in bytes): >> INFO org.apache.hadoop.hive.ql.exec.Task - set >> hive.exec.reducers.bytes.per.reducer=<number> >> INFO org.apache.hadoop.hive.ql.exec.Task - In order to limit the >> maximum number of reducers: >> INFO org.apache.hadoop.hive.ql.exec.Task - set >> hive.exec.reducers.max=<number> >> INFO org.apache.hadoop.hive.ql.exec.Task - In order to set a constant >> number of reducers: >> INFO org.apache.hadoop.hive.ql.exec.Task - set >> mapreduce.job.reduces=<number> >> ERROR org.apache.hadoop.hive.ql.exec.mr.ExecDriver - Exception: >> org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.authorize.AuthorizationException): >> *User: test_user@GRID.****.COM is not allowed to impersonate test_user* >> ERROR org.apache.hive.service.cli.operation.Operation - FAILED: >> Execution Error, return code 1 from >> org.apache.hadoop.hive.ql.exec.mr.MapRedTask >> >> test_user is the user I used to do all the tests. >> >> 2. The error is caused by authorization failure of the Hadoop Httpfs >> service, so, I added the following configuration to the core-site.xml >> configuration in Hadoop configuration directory, which didn't work >> >> <configuration> >> <property> >> <name>hadoop.proxyuser.*test_user*.groups</name> >> <value>*</value> >> </property> >> <property> >> <name>hadoop.proxyuser.*test_user*.hosts</name> >> <value>*</value> >> </property> >> </configuration> >> >> I talked with Hadoop team and they told me the test_user is not a user >> group recognized by Httpfs service, in order to run my test, they have to >> create a new user group and deploy it in Hadoop cluster. So, they suggest >> me a work-around, which is to avoid using user proxy when submitting >> MapReduce job. >> >> 3. I tried to comment out the proxy user configuration and change >> HADOOP_HOME and HADOOP_CONF_DIR to point to my own Hadoop copy, and it >> didn't work. >> >> Is there a way to avoid using the proxy user and submit a mapreduce using >> my own user name? >> >> 4. When submitting a Lens query, I know the first step is to query Hive >> metastore, second step is to convert lens query to Hive query, third step >> is to hand over the converted hive query to the driver hive/hive1, what are >> the following steps? Does lens use a Hive JDBC driver to connect to >> HiveServer2, and then submit the query to HiveServer2? I didn't find any >> related log in Hive log files. >> >> Thanks, >> >> On Thu, Jul 28, 2016 at 8:37 PM, amareshwarisr . <[email protected]> >> wrote: >> >>> Tao, >>> >>> Can you try restarting lensserver with --classpath /etc/hadoop/conf >>> (whatever is your hadoop conf directory) ? >>> >>> Thanks >>> >>> On Fri, Jul 29, 2016 at 3:04 AM, Tao Yan <[email protected]> wrote: >>> >>>> Hi Rajat & Amareshwari, >>>> >>>> I followed all the steps and it still give me the same error, and >>>> HADOOP_HOME also points to local file system, not HDFS. However, I found >>>> our Hadoop Cluster has the following configuration in mapred-site.xml: >>>> <property> >>>> <name>mapreduce.application.framework.path</name> >>>> <value>hdfs:/*****/hadoop-2.6.1.*****.tar.gz</value> >>>> </property> >>>> >>>> The default value is empty, and clients will try to find the mapreduce >>>> archive from local filesystem, and then try to submit the mapreduce job. I >>>> think this is the root cause of the exception since it is the exact same >>>> file name in the exception error message. Is there any approach to avoid >>>> this error on the lens or hive sides? >>>> >>>> BTW, when user submit a lens query, will it invoke the hive/hive1 >>>> driver, and which in turns call hiveserver2? I saw it is calling >>>> 'org.apache.hadoop.hive.ql.Driver' in the server log, is it part of the >>>> hive JDBC driver or Thrift driver? >>>> >>>> Thanks, >>>> >>>> On Wed, Jul 27, 2016 at 11:12 AM, Tao Yan <[email protected]> wrote: >>>> >>>>> Hi Rajat & Amareshwari, >>>>> >>>>> Thanks very much for your suggestions. I will follow the steps. >>>>> >>>>> BTW, will you please send me the lens-site.xml and hivedriver-site.xml >>>>> files? >>>>> >>>>> It seems when I added the MySQL database configuration in >>>>> lens-site.xml, Lens can directly talk with MySQL, is that right? >>>>> >>>>> Thanks. >>>>> >>>>> On Wed, Jul 27, 2016 at 5:13 AM, amareshwarisr . < >>>>> [email protected]> wrote: >>>>> >>>>>> Tao, >>>>>> >>>>>> here are some points which can help you. >>>>>> - Default examples setup works only with single node setup. Not sure >>>>>> if you running in multinode cluster. >>>>>> >>>>>> - For missing htrace class, can you try adding htrace jar from hadoop >>>>>> libraries in LENSCPPATH >>>>>> >>>>>> Thanks >>>>>> >>>>>> On Wed, Jul 27, 2016 at 9:49 AM, Tao Yan <[email protected]> wrote: >>>>>> >>>>>>> Hi Lens Developers, >>>>>>> >>>>>>> I have been doing Lens POC for my team for a while, and encountered >>>>>>> several issues which prevent me from querying the example data. A >>>>>>> brief summary of the issues: >>>>>>> >>>>>>> 1. Lens Query Failed to execute. >>>>>>> 2. Partition data is not correctly loaded in hive. >>>>>>> >>>>>>> I have read through all the documents in Lens website, and followed >>>>>>> step-by-step the 20 minutes demo. Following are the details for the >>>>>>> first >>>>>>> issue: >>>>>>> >>>>>>> a. It failed to execute the Lens query, and returned the following >>>>>>> error: >>>>>>> >>>>>>> *lens-shell>query execute cube select product_id, store_sales from >>>>>>> sales where time_range_in(order_time, '2015-04-11-00', '2015-04-13-00')* >>>>>>> *26 Jul 2016 23:08:15 [Spring Shell] INFO cliLogger - Query handle: >>>>>>> 69f44b77-97e9-4500-b385-a1881e5c365e* >>>>>>> *26 Jul 2016 23:08:22 [Spring Shell] INFO cliLogger - User query: >>>>>>> 'cube select product_id, store_sales from sales where >>>>>>> time_range_in(order_time, '2015-04-11-00', '2015-04-13-00')' was >>>>>>> submitted >>>>>>> to hive/hive1* >>>>>>> *26 Jul 2016 23:08:22 [Spring Shell] INFO cliLogger - Driver >>>>>>> query: 'INSERT OVERWRITE DIRECTORY >>>>>>> "file:/tmp/lensreports/hdfsout/69f44b77-97e9-4500-b385-a1881e5c365e" >>>>>>> SELECT ( sales . product_id ), sum(( sales . store_sales )) FROM >>>>>>> newdb.local_sales_aggr_fact1 sales WHERE ((((( sales . ot ) = >>>>>>> '2015-04-11' >>>>>>> ) or (( sales . ot ) = '2015-04-12' )))) GROUP BY ( sales . product_id >>>>>>> ) ' >>>>>>> and Driver handle: OperationHandle [opType=EXECUTE_STATEMENT, >>>>>>> getHandleIdentifier()=8d1f3b8a-a660-472f-bfb7-32d6b73d0532]* >>>>>>> *Command failed java.lang.NullPointerException* >>>>>>> >>>>>>> >>>>>>> b. The server logs shows the following error: >>>>>>> >>>>>>> 26 Jul 2016 23:34:44 [f3f5c221-e099-4f8e-9c32-42733365d3b6] >>>>>>> [pool-19-thread-7] INFO org.apache.hadoop.hive.ql.exec.mr.ExecDriver - >>>>>>> Executing: /export/apps/hadoop/latest/bin/hadoop jar >>>>>>> /export/home/dev_svc/lens/apache-hive-0.13.1-inm-bin/lib/hive-common-0.13.1-inm.jar >>>>>>> org.apache.hadoop.hive.ql.exec.mr.ExecDriver -plan >>>>>>> file:/tmp/dev_svc/hive_2016-07-26_16-34-41_205_3382750706353330702-8/-local-10003/plan.xml >>>>>>> -jobconffile >>>>>>> file:/tmp/dev_svc/hive_2016-07-26_16-34-41_205_3382750706353330702-8/-local-10002/jobconf.xml >>>>>>> 26 Jul 2016 23:34:47 [f3f5c221-e099-4f8e-9c32-42733365d3b6] >>>>>>> [pool-19-thread-7] ERROR org.apache.hadoop.hive.ql.exec.Task - >>>>>>> Execution failed with exit status: 1 >>>>>>> 26 Jul 2016 23:34:47 [f3f5c221-e099-4f8e-9c32-42733365d3b6] >>>>>>> [pool-19-thread-7] ERROR org.apache.hadoop.hive.ql.exec.Task - >>>>>>> Obtaining error information >>>>>>> 26 Jul 2016 23:34:47 [f3f5c221-e099-4f8e-9c32-42733365d3b6] >>>>>>> [pool-19-thread-7] ERROR org.apache.hadoop.hive.ql.exec.Task - >>>>>>> Task failed! >>>>>>> Task ID: >>>>>>> Stage-1 >>>>>>> >>>>>>> Logs: >>>>>>> >>>>>>> >>>>>>> c. The session logs shows the following error(*** is used to replace >>>>>>> internal cluster' hdfs path): >>>>>>> >>>>>>> 2016-07-20 17:45:04,103 ERROR [main]: mr.ExecDriver >>>>>>> (SessionState.java:printError(572)) - Job Submission failed with >>>>>>> exception >>>>>>> 'java.lang.IllegalArgumentException(Wrong FS: >>>>>>> hdfs:/*****/hadoop-2.6.1.*****.tar.gz, expected: file:///)' >>>>>>> >>>>>>> java.lang.IllegalArgumentException: Wrong FS: >>>>>>> hdfs:/*****/hadoop-2.6.1.****.tar.gz, >>>>>>> expected: file:/// >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.fs.FileSystem.checkPath(FileSystem.java:645) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.fs.FileSystem.makeQualified(FileSystem.java:465) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.fs.FilterFileSystem.makeQualified(FilterFileSystem.java:119) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.mapreduce.JobSubmitter.addMRFrameworkToDistributedCache(JobSubmitter.java:455) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:143) >>>>>>> >>>>>>> at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1297) >>>>>>> >>>>>>> at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1294) >>>>>>> >>>>>>> at java.security.AccessController.doPrivileged(Native Method) >>>>>>> >>>>>>> at javax.security.auth.Subject.doAs(Subject.java:422) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1671) >>>>>>> >>>>>>> at org.apache.hadoop.mapreduce.Job.submit(Job.java:1294) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.mapred.JobClient$1.run(JobClient.java:562) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.mapred.JobClient$1.run(JobClient.java:557) >>>>>>> >>>>>>> at java.security.AccessController.doPrivileged(Native Method) >>>>>>> >>>>>>> at javax.security.auth.Subject.doAs(Subject.java:422) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1671) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:557) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:548) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.hive.ql.exec.mr.ExecDriver.execute(ExecDriver.java:420) >>>>>>> >>>>>>> at >>>>>>> org.apache.hadoop.hive.ql.exec.mr.ExecDriver.main(ExecDriver.java:741) >>>>>>> >>>>>>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) >>>>>>> >>>>>>> at >>>>>>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) >>>>>>> >>>>>>> at >>>>>>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) >>>>>>> >>>>>>> at java.lang.reflect.Method.invoke(Method.java:483) >>>>>>> >>>>>>> at org.apache.hadoop.util.RunJar.run(RunJar.java:221) >>>>>>> at org.apache.hadoop.util.RunJar.main(RunJar.java:136) >>>>>>> >>>>>>> >>>>>>> d. Hive Cli shows the following result: >>>>>>> >>>>>>> hive (newdb)> describe formatted local_sales_aggr_fact1; >>>>>>> OK >>>>>>> # col_name data_type comment >>>>>>> >>>>>>> order_time timestamp >>>>>>> delivery_time timestamp >>>>>>> customer_id int >>>>>>> product_id int >>>>>>> promotion_id int >>>>>>> customer_city_id int >>>>>>> production_city_id int >>>>>>> delivery_city_id int >>>>>>> unit_sales bigint >>>>>>> store_sales double >>>>>>> store_cost double >>>>>>> max_line_item_price float >>>>>>> max_line_item_discount float >>>>>>> >>>>>>> # Partition Information >>>>>>> # col_name data_type comment >>>>>>> >>>>>>> pt string Process time partition >>>>>>> ot string Order time partition >>>>>>> dt string Delivery time partition >>>>>>> >>>>>>> # Detailed Table Information >>>>>>> Database: newdb >>>>>>> Owner: null >>>>>>> CreateTime: Mon Jul 25 16:21:03 PDT 2016 >>>>>>> LastAccessTime: UNKNOWN >>>>>>> Protect Mode: None >>>>>>> Retention: 0 >>>>>>> Location: file:/tmp/examples/aggrfact1 >>>>>>> Table Type: EXTERNAL_TABLE >>>>>>> Table Parameters: >>>>>>> EXTERNAL TRUE >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.dt.first >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.dt.holes.size 0 >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.dt.latest >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.dt.storage.class >>>>>>> org.apache.lens.cube.metadata.timeline.EndsAndHolesPartitionTimeline >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.ot.first >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.ot.holes.size 0 >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.ot.latest >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.ot.storage.class >>>>>>> org.apache.lens.cube.metadata.timeline.EndsAndHolesPartitionTimeline >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.pt.first >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.pt.holes.size 0 >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.pt.latest >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.DAILY.pt.storage.class >>>>>>> org.apache.lens.cube.metadata.timeline.EndsAndHolesPartitionTimeline >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.dt.first >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.dt.holes.size 0 >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.dt.latest >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.dt.storage.class >>>>>>> org.apache.lens.cube.metadata.timeline.EndsAndHolesPartitionTimeline >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.ot.first >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.ot.holes.size 0 >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.ot.latest >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.ot.storage.class >>>>>>> org.apache.lens.cube.metadata.timeline.EndsAndHolesPartitionTimeline >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.pt.first >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.pt.holes.size 0 >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.pt.latest >>>>>>> >>>>>>> cube.storagetable.partition.timeline.cache.HOURLY.pt.storage.class >>>>>>> org.apache.lens.cube.metadata.timeline.EndsAndHolesPartitionTimeline >>>>>>> cube.storagetable.partition.timeline.cache.present true >>>>>>> >>>>>>> cube.storagetable.time.partcols pt,ot,dt >>>>>>> transient_lastDdlTime 1469574936 >>>>>>> # Storage Information >>>>>>> SerDe Library: >>>>>>> org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe >>>>>>> InputFormat: org.apache.hadoop.mapred.TextInputFormat >>>>>>> OutputFormat: >>>>>>> org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat >>>>>>> Compressed: No >>>>>>> Num Buckets: 0 >>>>>>> Bucket Columns: [] >>>>>>> Sort Columns: [] >>>>>>> Storage Desc Params: >>>>>>> field.delim , >>>>>>> serialization.format , >>>>>>> Time taken: 6.435 seconds, Fetched: 73 row(s) >>>>>>> >>>>>>> >>>>>>> Because the query is finally against the hive table >>>>>>> *local_sales_aggr_fact1, >>>>>>> which use the storage local:* >>>>>>> >>>>>>> <x_storage classname="org.apache.lens.cube.metadata.HDFSStorage" >>>>>>> name="local" xmlns="uri:lens:cube:0.1" >>>>>>> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; >>>>>>> xsi:schemaLocation="uri:lens:cube:0.1 cube-0.1.xsd "> >>>>>>> <properties> >>>>>>> *<property name="storage.url" value="file:///"/>* >>>>>>> </properties> >>>>>>> </x_storage> >>>>>>> >>>>>>> >>>>>>> *e. So, I tried to change the value from "file:///" to >>>>>>> "hdfs:/hadoop-host:port/", (similar to >>>>>>> examples/resources/local-cluster-storage.xml), which didn't work.f. I >>>>>>> also >>>>>>> tried to change the fact table >>>>>>> "examples/resources/sales-aggr-fact1.xml"'s >>>>>>> location from "/tmp/examples/aggrfact1" to HDFS path, and then add >>>>>>> partition, it failed with the error:* >>>>>>> lens-shell>fact add partitions --fact_name sales_aggr_fact1 >>>>>>> --storage_name local --path >>>>>>> examples/resources/sales-aggr-fact1-local-parts.xml >>>>>>> *Command failed javax.ws.rs.InternalServerErrorException: HTTP 500 >>>>>>> Request failed.-- * >>>>>>> >>>>>>> >>>>>>> Corresponding Server logs: >>>>>>> >>>>>>> *Caused by: java.lang.NoClassDefFoundError: org/htrace/Trace* >>>>>>> at >>>>>>> org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:214) >>>>>>> ~[hadoop-common-2.6.1.52.jar:na] >>>>>>> at com.sun.proxy.$Proxy89.getFileInfo(Unknown Source) >>>>>>> ~[na:na] >>>>>>> at >>>>>>> org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:752) >>>>>>> ~[hadoop-hdfs-2.6.1.52.jar:na] >>>>>>> >>>>>>> >>>>>>> g. I also tried to change the hive table's location from >>>>>>> file:/tmp/examples/aggrfact1 to a HDFS location, and the Lens query >>>>>>> returned the same error. >>>>>>> >>>>>>> >>>>>>> For the second issue. I tried to query the hive table directory and >>>>>>> found the data is not loaded, because in the examples, partitions' >>>>>>> location >>>>>>> is example/resource/..., which is not an absolute path from root '/', >>>>>>> so, I >>>>>>> changed it to an absolute path, and the hive query 'Select * from >>>>>>> newdb.local_sales_aggr_fact1' is able to return the data, but the >>>>>>> converted >>>>>>> lens query failed in the mapreduce stage because it cannot find the >>>>>>> local >>>>>>> filesystem path I assigned. >>>>>>> >>>>>>> B*TW, I use the company's hadoop cluster, with hadoop version >>>>>>> 2.6.1, I setup a hive on top of that using the version hive-0.13.1-inm >>>>>>> downloaded from Lens website, and setup a mysql database as the >>>>>>> metastore.* >>>>>>> >>>>>>> *Could you please help me resolve the above two issues? I really >>>>>>> appreciate that.* >>>>>>> >>>>>>> >>>>>>> *Tao Yan* >>>>>>> Software Engineer >>>>>>> Data Analytics Infrastructure Tools and Services >>>>>>> >>>>>>> >>>>>>> >>>>>>> 206.250.5345 >>>>>>> [email protected] >>>>>>> https://www.linkedin.com/in/taousc >>>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> -- >>>>> >>>>> *Tao Yan* >>>>> Software Engineer >>>>> Data Analytics Infrastructure Tools and Services >>>>> >>>>> >>>>> >>>>> 206.250.5345 >>>>> [email protected] >>>>> https://www.linkedin.com/in/taousc >>>>> >>>> >>>> >>>> >>>> -- >>>> >>>> *Tao Yan* >>>> Software Engineer >>>> Data Analytics Infrastructure Tools and Services >>>> >>>> >>>> >>>> 206.250.5345 >>>> [email protected] >>>> https://www.linkedin.com/in/taousc >>>> >>> >>> >> >> >> -- >> >> *Tao Yan* >> Software Engineer >> Data Analytics Infrastructure Tools and Services >> >> >> >> 206.250.5345 >> [email protected] >> https://www.linkedin.com/in/taousc >> > > -- *Tao Yan* Software Engineer Data Analytics Infrastructure Tools and Services 206.250.5345 [email protected] https://www.linkedin.com/in/taousc
