The epic 

Jira LegacyserverSystem JIRAcolumnskey,summary,type,created,updated,due,assignee,reporter,priority,status,resolutionmaximumIssues20jqlQueryissueKey in (SWC-4488,PLFM-4435,SWC-2329,WW-25,SWC-4588,WW-72)

The epic This is the main statistic that the users are currently looking for, it provides a way for project owners, funders and data contributor to monitor the interest over time in the datasets published in a particular project, which then reflects on the interest on the project itself and it is a metric of the value provided by the data in the project. This kind of data is related specifically to the usage of the platform by synapse users, since without being authenticated the downloads are not available. This is part of a generic category of statistics that relates to the entities and metadata that is stored in the backend and it's only a subset of aggregate statistic that can be exposed (

Introduction

It is clear that there is the need for the platform to provide some statistics about the usage of the data within synapse: discussions around various aspects and statistics to gather and expose have been going on for several years.

There are different statistics that the users are currently interested in and different levels of understanding of what should be exposed by the API. In particular we identified 3 main points that the users are focusing on and that are related but need clarifications:

1. Downloads count
2. Page views
3. Data breaches

Downloads Count

Introduction

It is clear that there is the need for the platform to provide some statistics about the usage of the data within synapse: discussions around various aspects and statistics to gather and expose have been going on for several years.

There are different statistics that the synapse projects owner and administrators are currently interested in and different levels of understanding of what should be exposed by the API. In particular there are 3 main points of discussion that are related but need clarifications:

1. Downloads Count
2. Page Views
3. Data Breaches/Audit Trail

Downloads Count

This is the main statistic that the users are currently looking for, it provides a way for project owners, funders and data contributor to monitor the interest over time in the datasets published in a particular project, which then reflects on the interest on the project itself and it is a metric of the value provided by the data in the project. This kind of data is related specifically to the usage of the platform by synapse users, since without being authenticated the downloads are not available. This is part of a generic category of statistics that relates to the entities and metadata that is stored in the backend and it's only a subset of aggregate statistic that can be exposed (e.g. number of projects, users, teams etc).

Page Views

This metric is also an indicator to monitor the interest but it plays a different role and focuses on the general user activity over the synapse platform as a whole. While it might be an indicator for a specific project success it captures a different aspect that might span to different type of clients used to interface on the Synapse API and that include information about users that are not authenticated into synapse. For this particular aspect there are tools already integrated (E.g. google analytics) that collect analytics on the user interactions. Note however that this information is not currently available to the synapse users, nor setup in a way to produce information about specific projects pages, files, wikis etc.

Data Breaches/Audit Trail

Another aspect that came out and might seem related is the identification of when/what/why of potential data breaches (e.g. a dataset was released even though it was not supposed to). This relates to the audit trail of users activity in order to identify potential offenders. While this information is crucial it should not be exposed by the API, and a due process is in place in order to access this kind of data.

Project Statistics

With this brief introduction in mind this document focuses on the first kind of data that can be collected and exposed by the API. While the number of page views and in general data collected about user interaction with the portal (and other clients) is an important aspect to consider we treat it as a different issue all together that can be tackled and discussed separately and that might be included in a future release as part of the statistics exposed by the API.

For the first implementation we do not plan to include the page views or analysis of anonymous user interactions in the statistics, but instead we will focus on the (synapse) user downloads only.

In the following we collect the various uses cases that were highlighted and a brief description of the current situation as well as a proposed API design to integrate in the synapse platform to expose the statistics.

Download Statistics

For the first phase we focus on exposing statistics about file downloads, in particular about download counts and count of users that downloaded a file.

Use Cases

The main driving use cases for the feature is to be able to monitor the overall dataset usage of the project as well as the usage of the single dataset overtime. 

We provide a list of use cases that were discussed with (internal) users of the synapse platform and from documents with some relevant use cases (See

...

• Use cases 5 and 11 are currently removed as it is not a request.
• Use case 6 is a nice to have, we might want to skip this in the first implementation.
• Use case 12 is a nice to have, not a priority.

Considerations

In general the idea is to collect data over the number of file downloads and the number of unique users that downloaded files within a project, providing some minimal filtering options. Additional filtering/data cleaning options that we might need to consider include: annotations, team exclusion (e.g. to reduce noise, I want to exclude from the statistics the users that are part of some administrative sage team ~ tricky as sage team users might actually work with the data). This might be part of a cleaning pipeline when we gather statistics and we might keep the filtering only at the level of time frame.

In the following we list some consideration about the use cases that we received:

• Aside from the count of downloads there is also the need to aggregate this data in a way that captures the trend of file downloads over time. For example the user is interested to see the number of downloads within a project or for a specific file grouped daily, weekly, monthly, yearly. There was no specific request to have averages but we could think of including it.
• Note that the information about the number of downloads might also appear in the file entities in a view, while no specific request was done for files (handles) linked in a table. In general the use cases focus on statistics about downloads over FileEntity.
• We might consider an additional dedicated permission that could be used to allow access to statistics (e.g. limiting its access by default). On the other end the use case for this is not defined, it should not be a problem to use the (computed) READ permission on the entity for statistics that do not contain identifiable data and expose aggregations only. We can start simple and use the canRead permission computed for entity (See Entity Permissions) and if needed in the future add a new type of permission specific for statistics (e.g. VIEW_STATISTICS ACCESS_TYPE).
  Note that if a file is not accessible to the user its statistics should not be accessible, if a folder is not accessible to the user the statistics about the files in the folder should not be accessible (unless the files have local permissions that allow access to them).
• Also note that the value of the statistics about a parent element (e.g. the project) should maintain consistency and include the count relative to the child objects no matter the permissions of the child objects (e.g. in other words if I change the permissions of a child entity, the aggregate information about the parent should not change).
• File entities are versioned, we would need to have a way to gather statistics for a specific version of the entity as well as the total among all the versions.
• File entities might have previews, we should avoid including in the count the downloads of the previews.
• Note from John: Is the team filtering really needed? It appears so from the doc 

  Lref gdrive file
  url https://docs.google.com/document/d/1t3OL3TnORZwpHOAgLuUt8NNUTLGjDuGj1UUrpggj54k/edit

  , but the actual statistics reported for downloads do not seem to filter by team (See screenshot below)
• Filtering the information might be contextual, for example filtering by a specific team might mean to filter by the current team members or depending on the team members at the time of the download: it seems that the users are oriented towards the first option, a team filter might be used to limit the statistics to a limited set of users. This poses an interesting question: should we limit the team filtering to teams with at least X users? (e.g. to avoid people misusing the statistics to identify specific user behavior). Also adding the option to filter the statistics by team adds a great deal of complexity in computing and storing the statistics.
• Use Case 12 is from Andrew L. for the dream challenges, is not a strong use case but a nice to have.

Current Situation

Currently the statistics about the file downloads are collected in various ways mostly through the DW, using /wiki/spaces/DW/pages/796819457 of the data collected to run ad-hoc queries for aggregations as well as through dedicated clients (See Synapse Usage Report).

• The process is relatively lengthy and requires non trivial technical skills
• The data is limited to a 6 months window, the current solution to this problem is to store incremental updates on an external source (cvs file on S3)
• The data cannot be easily integrated in the synapse portal or other components (in some cases the files are manually annotated with the number of downloads)
• The system has an all or nothing policy for accessing the data, that is (for good reason) only accessible to a specific subset of synapse employees, this does not allow the users of the synapse platform to access this kind of data without asking a synapse engineer

An example of usage report generated using the Synapse Usage Report written by Kenny Daily using the data warehouse:

Image Removed

Files and Downloads

Files in synapse are referenced through an abstraction (FileHandle) that maintain the information about the link to the content of the file itself (e.g. an S3 bucket). A file handle is then referenced in many places (such as FileEntity and WikiPage, see FileHandleAssociateType) as pointers to the actual file content. In order to actually download the content the synapse platform allows to generated a pre-signed url (according to the location where the file is stored) that can be used to directly download the file. Note that the platform has no way to guarantee that the pre-signed url is actually used by the client in order to download a file. Every single pre-signed url request in the codebase comes down to a single method getURLForFileHandle.

In the context of a project and project files downloads we are interested in particular to the entity of type FileEntity and the download request made for the associated file handles (which does not include the preview handle) specifically in the context of a particular project or file entity.

There are also different ways to actually get pre-signed urls for file handles that are exposed through the API. For the context of project and files download we are interested in specific operations, in particular there are several API endpoints that are used to request a pre-signed url to download the content of entities of type FileEntity (For a complete list of endpoints that reference file handles see Batch FileHandle and File URL Services):

...

/entity/{id}/file /entity/{id}/version/{versionNumber}/file

...

Allows to get a batch of pre-signed urls for a set of file handles. The request (BatchFileRequest) specifically requires the id of the object that reference the file handle id and the type of the object that reference the file handle (See FileHandleAssociation and FileHandleAssociateType)

...

Allows to get the pre-signed url of the file handle with the given id. The request must contain within the parameters the FileHandleAssociateType and the id of the object that reference the file. Similarly to the deprecated /entity/{id}/file will return a 307 with the redirect to the pre-signed url

...

The main aspect that we want to capture is that in general any relevant file download should include the triplet associateObjectType, associateObjectId and fileHandleId (See the FileHandleAssociation) that allows us to understand the source of the file download in the context of a request.

In the following we provide some basic download statistics computed for the last 30 days worth of data (as of 06/26/2019) as reported by the data warehouse:

"direct" downloads statistics

...

...

...

• /entity/{id}/file
• /entity/{id}/version/{version}/file

...

"Batch and bulk" Downloads

...

...

...

Proposed API Design

...

To this end we propose an API that integrates into the current /asynchronous/job API (See Asynchronous Job API) so that a client can send a request to compute certain statistics and wait for the final response polling the API for the result. This allows to offload the computation to a background worker keeping the API servers free of heavy computation. The two main objects that the statistics API will need to extend are: AsynchronousRequestBody and AsynchronousResponseBody that represent respectively the request for a background job and the response from the job (returned as part of the AsynchronousJobStatus).

Note: In the actual implementation we might have a generic SynapseStatistics interface used as a marker of any statistics request, for brevity in the following we simply refer to the EntityStatistics objects.

Request Objects

In the following we provide a list of object representations for requests of entity statistics:

<<abstract>> EntityStatisticsRequest <extends> AsynchronousRequestBody

Common parent object for a job request to compute statistics of an entity. This object is an AsynchronousResponseBody that will be sent to the /asynchronous/job endpoint in order to ask for the computation of a certain statistic.

...

DownloadStatisticsRequest <extends> EntityStatisticsRequest

The actual job request that extends the EntityStatisticsRequest to get the download statistics of an entity, this will be used to get download and users counts only.

...

DownloadBucketsStatisticsRequest <extends> DownloadStatisticsRequest

Extends the DownloadStatisticsRequest in order to compute the download counts (along with the unique users count) bucketed into a fixed amount of time, e.g. grouping by a given time frame, which allows to build an histogram and have the download trend over the specified time frame.

...

Response Objects

In the following we provide a list of object representation for the statistics API:

<<abstract>> EntityStatisticsResponse <extends> AsynchronousResponseBody

Common parent object for the response regarding a request for statistics on an entity. This object is an AsynchronousResponseBody that will be included as part of the AsynchronousJobStatus when requesting the status of the job.

...

...

DownloadStatisticsResponse <extends> EntityStatisticsResponse

Represents the response for a job request for computing the download statistics for an entity (In response to a DownloadStatisticsRequest).

...

DownloadBucketsStatisticsResponse <extends> DownloadStatisticsResponse

Represents the response for a job request for computing the bucketed download statistics for an entity (in response to a DownloadBucketsStatisticsRequest). Note that the response extends the DownloadStatisticsResponse so that it includes the total counts.

...

StatisticsCountBucket

The purpose of this object is to include information about the count of a certain metric within a specific time frame:

...

Endpoints

The API reuses the endpoints from the Asynchronous Job API (We could potentially add a dedicated /statistics endpoint just for clarity).

...

• DownloadStatisticsRequest
• DownloadBucketsStatisticsRequest

...

• DownloadStatisticsResponse
  or the 
• DownloadBucketsStatisticsResponse

...

• The entity specified in the request must be a project or a file entity (if not 400)
• The user should have view permission on the entity specified in the body (if not 403)
• The DownloadBucketsStatisticsRequest will be used to compute paginated results. The value of the "limit" parameter is restricted to a maximum value of 100.

...

Additionally we propose to have dedicated statistics endpoints to be consistent with the current API design that accepts the above requests:

...

• DownloadStattisticsRequest 
• DownloadBucketsStatisticsRequest

...

the main driving use case, that is:

• A funder and/or project creator would like to have a way to understand if the project is successful and if its data is used.

There are several metrics that can be used in order to determine the usage and success of a project, among which:

• Project Access (e.g. page views)
• Number of Downloads
• Number of Uploads
• User Discussions

Current Situation

Currently the statistics about a project are collected in various ways mostly through the DW, using /wiki/spaces/DW/pages/796819457 of the data collected to run ad-hoc queries for aggregations as well as through dedicated clients (See Synapse Usage Report).

First Phase Proposal

In a first phase we want to have a minimal set of statistics that are exposed from the synapse platform API that provides a way to fulfill the use case. In particular we identified the following aspects that allows to have an initial implementation that can be extended in a later moment if needed:

• Expose statistics about number of download and number of uploads
• Expose statistics about the number of unique users that downloaded and/or uploaded
• Statistics are collected on a per project basis (no file level statistics)
• Statistics limited to the past 12 months (without including the current month)
• Statistics aggregated monthly (no total downloads or total users)
• Statistics access is restricted through a new ACCESS_TYPE VIEW_STATISTICS, initially granted to project owners and administrators
• No run-time filtering

Files, Downloads and Uploads

Files in synapse are referenced through an abstraction (FileHandle) that maintain the information about the link to the content of the file itself (e.g. an S3 bucket). A file handle is then referenced in many places (such as FileEntity and WikiPage, see FileHandleAssociateType) as pointers to the actual file content. In order to actually download the content the synapse platform allows to generated a pre-signed url (according to the location where the file is stored) that can be used to directly download the file. Note that the platform has no way to guarantee that the pre-signed url is actually used by the client in order to download a file. Every single pre-signed url request in the codebase comes down to a single method getURLForFileHandle.

In the context of a project we are interested in particular to download (and/or uploads) of entities of type FileEntity and TableEntity (See What is a "download" in Synpase?) and the download request made for the associated file handles.

There are also different ways to actually get pre-signed urls for file handles that are exposed through the API. For the context of project and files download we are interested in specific operations, in particular there are several API endpoints that are used to request a pre-signed url to download the content of entities of type FileEntity (For a complete list of endpoints that reference file handles see Batch FileHandle and File URL Services):

The main aspect that we want to capture is that in general any relevant file download should include the triplet associateObjectType, associateObjectId and fileHandleId (See the FileHandleAssociation) that allows us to understand the source of the file download in the context of a request.

In the following we provide some basic download statistics computed for the last 30 days worth of data (as of 06/27/2019) as reported by the data warehouse:

"direct" downloads statistics

"Batch and bulk" Downloads

Proposed API Design

The current API design uses a polymorphic approach to access certain kind of objects, in particular related to Projects, Folders and Files (See Entities, Files, and Folders Oh My!), exposing a single prefixed endpoint for CRUD operations (/entity). This has the effect that a GET request to the /entity/{id} endpoint for a specific entity might return a different response type (See the Entity Response Object). For a first implementation we would need an endpoint to expose statistics about a project.

In general computing statistics might be an expensive operation, moreover in the future we might want to extend the API to include several different types of statistics. For the current use case we can potentially pre-compute statistics aggregates monthly for the projects so that we can serve them relatively quickly with a single lookup. While we cannot guarantee that all kind of statistics that will be exposed in the future can be pre-computed and will return within a reasonable response time to ease the clients integration we propose to have a dedicated endpoint that will return the statistics for a project within a single synchronous HTTP call.

If in the future we require more complex and/or expensive computation for certain statistics we can extend the API to integrate with the /asynchronous/job API (See Asynchronous Job API) in order to offload the computation to a background worker.

Endpoints

We propose to introduce a dedicated /statistics endpoint that will serve as main entry point to statistics requests. The project statistics are nested within this endpoint:

 The endpoint accepts the following optional URL parameters:

GET /statistics/project/syn123?downloads=true&uploads=false

Response Objects

ProjectStatistics

Represents the response for the project statistics request:

DownloadStatistics/UploadStatistics

StatisticsCountBucket

The purpose of this object is to include information about the count of a certain metric within a specific time frame (in this case monthly):

{
	"lastUpdatedOn: "2019-26-06T01:01:00.000Z",
	"downloads": {
		"lastUpdatedOn": "2019-26-06T01:01:00.000Z",
		"monthly": [{
			"startDate": "2019-01-06T00:00:00.000Z", 
			"count": 1230,
			"usersCount": 10
		},
		{
			"startDate": "2019-01-05T00:00:00.000Z", 
			"count": 10000,
			"usersCount": 100
		}]
	},
	"uploads": {
		"lastUpdatedOn": "2019-26-06T01:01:00.000Z",
		"monthly": [{
			"startDate": "2019-01-06T00:00:00.000Z", 
			"count": 51200,
			"usersCount": 200
		},
		{
			"startDate": "2019-01-05T00:00:00.000Z", 
			"count": 10000,
			"usersCount": 100
		}]
	}
}

Proposed Backend Architecture

In order to serve the statistics from the synapse API we need a way to efficiently access the statistics without heavy loading the web instances of the API.

Image Added

Kinesis Firehose

The idea is to use Kinesis Firehose to send the events we are interested in (e.g. file upload and file download) as json records, the kinesis stream will funnel the records to firehose that will be converted to the columnar format Apache Parquet (the table schema is created and managed in AWS glue) and stored to an S3 bucket.

For the first phase we collect statistics for download and uploads, for each type of event we will have a separate stream, an example of JSON object sent to the kinesis stream for a download event:

{
    "timestamp": "1562626674712",
    "stack": "dev",
    "instance": 123,
    "projectId": 456,
    "userId": 5432,
    "associationType": "FileEntity",
    "associationId": 12312
    "fileHandleId": 6789
}

Athena

Once the data is in S3 it can be queried with AWS Athena with standard SQL. For the JSON schema example above we can run an SQL query grouping for example by projectId (and filtering by timestamp) and counting the records as well as the distinct users (Note: Athena uses Presto as query engine, that supports approximate aggregations such as approx_distinct).

Athena can be accessed using the Amazon SDK directly in Java. This allows us to implement synapse background workers that periodically queries the data using Athena in order to compute and store manageable aggregates that can be queried directly from the synapse services.

Given that we will query the data stored in S3 month by month, we can partition the data directly so that Athena will scan only the needed records (See https://docs.aws.amazon.com/athena/latest/ug/partitions.html). We can define partitions directly in the S3 schema created by firehose and leverage Athena partitioning (through Hive, see https://aws.amazon.com/blogs/big-data/top-10-performance-tuning-tips-for-amazon-athena). For example using s3://prod.log.sagebase.org/fileDownloads/year=!{timestamp:yyyy}/month=!{timestamp:MM/day=!{timestamp=dd}/ when defining the firehose stream.

Statistics Tables

In a first phase we only provide monthly aggregates per project to the client, to this end we can store the monthly aggregates into RDS using dedicated statistics tables. If we need to store more fine grained statistics (e.g. daily, or at the file level) we can move in a later moment to a more scalable solution (e.g. DynamoDB seems a good fit). In the following we provide an initial guide on the tables that might be needed (not final, and most likely will change during the implementation).

In order to compute the monthly aggregates we want to make sure that the workers only queries a month worth of data at the time, in particular since we only expose the past months aggregation we do not need to gather the statistics for the current month and once the statistics for a given month are stored we do not have to recompute them (unless we specifically want to). For each type of statistics we store the timestamp of the last successful run for a given year/month into a dedicated table statistics_monthly_status:

Image Added

A dedicated worker can periodically query this table in order to get the months for which the aggregates still needs to be performed and submit a message to a dedicated queue that will be processed and polled by dedicated message driven workers. (Note that each time a worker runs, the query will need to scan all the data for the considered month as we need to get estimates on the number of unique users that downloaded/uploaded files on a monthly basis).

The monthly aggregates for each project is then stored into a dedicated table statistics_project_monthly:

Image Added

The table contains for each project, year and month the count of downloads, uploads, the number of unique users that downloaded and uploaded files as well as the last time the statistic for that particular month was updated (per download and upload). This table can be queried directly by the service layer in the synapse API in read only.

Statistics Workers

We will initially need a few different workers that will aggregate the statistics periodically using the Athena SDK:

• MonthlyProjectStatisticsWorker: Will run periodically to check the statistics_monthly_status table on the status of the past 12 months, if a month is missing or failed will push a message to a dedicated queue that will be picked up by the following workers.
• ProjectDownloadStatisticsAggregator: Process messages pushed by the MonthlyStatisticsWorker to (re)compute the statistics for a given month, run the SQL query on the S3 data for the downloads streams using Athena and updates the statistics_project_monthly table above.
• ProjectUploadStatisticsAggregator: Similar to the DownloadStatitisticsAggregator will perform the aggregation for uploads, updating the statistics_project_monthly table

The workers will potentially need to batch the query result into a smaller set, potentially running multiple transactions to save the data.

This initial setup will allow us to serve the statistics for a given project, but there might be some issues:

• Zero downloads/uploads problem: We can avoid storing unnecessary data for each project if for a given month there were no uploads or downloads, at the application level we can simply return a 0 count if the record is not in the table for a given month. This poses a problem since we cannot discriminate between a zero count or a "not yet computed" case. We can work around this by using the statistics_monthly_status table. If for a given project and month we never have downloads or uploads but we know that the month was processed we know that we had no downloads or uploads.
• Last update time: The last update time for a given statistics (download and/or upload) is valid only if the project has had in the last month at least one download or one upload. We can use the global last_update for the given statistics from the statistics_monthly_status table instead, but it's still an approximation: updating the statistics table might take some time, multiple transactions are potentially needed and even though the statistics for a given project can be retrieved the last_update might not reflect the fact that the worker is still in progress.
• Delays in the stream: Most likely there is going to be a slight delay between the time a record is sent to kinesis and the time it's stored in S3, we should take this delay into account and make sure we read ahead when we run the query for the month preceding the current one if we are within a given timeframe (e.g. at the beginning of the month we can aggregate data loading a short window of the data past the current month). 

Additionally we might want to store the initial date when we started collecting statistics, this would allow us to truncate the months past that date so that we can report an "unknown" status to the client.

Web Client Integration

The web client should have a way to show the statistics for a project or a specific file, some initial ideas:

...

• Have a dedicated menu item that leads to a statistics dashboard Might want to have a dedicated wiki widget that reuses the API(should be visible only to the project owner/administrator)