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AMPS Server Documentation 5.3.4
AMPS Server Documentation 5.3.4
  • Welcome to AMPS 5.3.4
  • Introduction to AMPS
    • Overview of AMPS
    • Getting Started With AMPS
      • Installing AMPS
      • Starting AMPS
      • JSON Messages - A Quick Primer
      • spark: the AMPS command-line client
      • Evaluating AMPS on Windows or MacOS
      • Galvanometer and RESTful Statistics
    • AMPS Basics: Subscribe and Publish to Topics
    • State of the World (SOW): The Message Database
      • When Should I Store a Topic in the SOW?
      • How Does the SOW Work?
      • Configuration
      • Queries
      • Atomic Query and Subscribe
      • Advanced Messaging and the SOW
    • Record and Replay Messages with the AMPS Transaction Log
    • Message Queues
    • Scenario and Feature Reference
      • Recovery Strategies
    • Getting Support
    • Advanced Topics
    • Next Steps
  • AMPS Evaluation Guide
    • Introduction
    • Evaluation and Development with AMPS
    • Tips on Measuring Performance
    • Next Steps
  • AMPS User Guide
    • Introduction
      • Product Overview
      • Requirements
      • Organization of this Guide
        • Documentation Conventions
      • Technical Support
    • Installing and Starting AMPS
      • Installing AMPS
      • Starting AMPS
      • Production Configuration
    • Subscribe and Publish
      • Topics
      • Filtering Subscriptions by Content
      • Conflated Subscriptions
      • Replacing Subscriptions
      • Messages in AMPS
      • Message Ordering
      • Retrieving Part of a Message
    • AMPS Expressions
      • Syntax
      • Identifiers
      • AMPS Data Types
      • Grouping and Order of Evaluation
      • Logical Operators
      • Arithmetic Operators
      • Comparison Operators
      • LIKE Operator
      • Conditional Operators
      • Working with Arrays
      • Regular Expressions
      • Performance Considerations
    • AMPS Functions
      • AMPS Function Overview
      • String Comparison Functions
      • Concatenating Strings
      • Managing String Case
      • Replacing Text in Strings
      • String Manipulation Functions
      • Date and Time Functions
      • Array Reduce Functions
      • Geospatial Functions
      • Numeric Functions
      • CRC Functions
      • Message Functions
      • Client Functions
      • Coalesce Function
      • AMPS Information Functions
      • Typed Value Creation
      • Constructing Fields
      • Aggregate Functions
    • State of the World (SOW) Topics
      • How Does the SOW Work?
      • Using the State of the World
      • Understanding SOW Keys
      • Indexing SOW Topics
      • Programmatically Deleting Records from the Topic State
      • SOW Maintenance
        • Creating a Maintenance Schedule for a Topic
        • Setting Per-Message Lifetime
      • Storing Multiple Logical Topics in One Physical Topic
    • Querying the State of the World (SOW)
      • Overview of SOW Queries
      • Query and Subscribe
      • Historical SOW Topic Queries
      • Managing Result Sets
      • Batching Query Results
    • Out-of-Focus Messages (OOF)
    • State of the World Message Enrichment
    • Incremental Message Updates
      • Using Delta Publish
      • Understanding Delta Publish
      • Delta Publish Support
    • Receiving Only Updated Fields
      • Using Delta Subscribe
      • Identifying Changed Records
      • Conflated Subscriptions and Delta Subscribe
      • Select List and Delta Subscribe
      • Options for Delta Subscribe
    • Conflated Topics
    • Aggregation and Analytics
      • Understanding Views
      • Defining Views and Aggregations
      • Constructing Field Contents
      • Best Practices for Views
      • View Examples
      • Aggregated Subscriptions
    • Record and Replay Messages
      • Using the Transaction Log and Bookmark Subscriptions
      • Understanding Message Persistence
      • Configuring a Transaction Log
      • Replaying Messages with Bookmark Subscription
      • Managing Journal Files
      • Using amps-grep to Search the Journal
    • Message Queues
      • Getting Started with AMPS Queues
      • Understanding AMPS Queuing
      • Advanced Messaging and Queues
      • Replacing Queue Subscriptions
      • Handling Unprocessed Messages
      • Advanced Queue Configuration
      • Queue Subscriptions Compared to Bookmark Replays
    • Message Types
      • Default Message Types
      • BFlat Messages
      • MessagePack Messages
      • Composite Messages
      • Protobuf Message Types
      • Struct Message Types
    • Command Acknowledgment
      • Requesting Acknowledgments
      • Receiving Acknowledgments
      • Bookmark Subscriptions and Completed Acknowledgments
      • Bookmark Subscriptions and Persisted Acknowledgments
      • Acknowledgment Conflation and Publish Acknowledgements
    • Transports
      • Client Connections
      • Replication Connections
      • Transport Filters
    • Running AMPS as a Linux Service
      • Installing the Service
      • Configuring the Service
      • Managing the Service
      • Uninstalling the Service
    • Logging
      • Configuring Logging
      • Log Message Format
      • Message Levels
      • Message Categories
      • Logging to a File
      • Logging to a Compressed File
      • Logging to Syslog
      • Logging to the Console
      • Looking up Errors with ampserr
    • Event Topics
      • Client Status Events
      • SOW Statistics Events
      • Persisting Event Topics
    • Utilities
      • Command-Line Basic Client
      • Dump clients.ack File
      • Dump journal File
      • Dump queues.ack File
      • Dump SOW File
      • Dump Journal Topic Index File
      • Find Bookmark or Transaction ID in Transaction Log
      • Find Information in Error Log or Transaction Log
      • Identify Type of AMPS File
      • List/Explain Error Codes
      • Query Statistics Database
      • Statistics Database Report
      • Storage Performance Testing
      • Submit Minidump to 60East
      • Obsolete Utility: Upgrade File Formats
    • Monitoring AMPS
      • Statistics Collection
        • Time Range Selection
        • Output Formatting
      • Galvanometer
      • Configuring Monitoring
    • Automating AMPS with Actions
    • Replicating Messages Between Instances
      • Replication Basics
      • Configuring Replication
      • Replication Configuration Validation
      • Replication Resynchronization
      • Replication Compression
      • Destination Server Failover
      • Two-Way Replication
      • PassThrough Replication
      • Guarantees on Ordering
      • Replication Security
      • Understanding Replication Message Routing
      • Replicated Queues
      • Replication Best Practices
    • Highly Available AMPS Installations
      • Overview of High Availability
        • Example: Pair of Instances for Failover
        • Example: Regional Distribution
        • Example: Regional Distribution with HA
        • Example: Hub and Spoke / Expandable Mesh
      • Details of High Availability
      • Slow Client Management and Capacity Limits
      • Message Ordering Considerations
    • Operation and Deployment
      • Capacity Planning
      • Linux OS Settings
      • Upgrading AMPS
      • Using AMPS with a Proxy
      • Operations Best Practices
    • Securing AMPS
      • Authentication
      • Entitlement
      • Providing an Identity for Outbound Connections
      • Protecting Data in Transit Using TLS/SSL
    • Troubleshooting AMPS
      • Planning for Troubleshooting
      • Diagnostic Utilities
      • Finding Information in the Log
      • Reading Replication Log Messages
      • Troubleshooting Disconnected Clients
      • Troubleshooting Regular Expression Subscriptions
    • AMPS Distribution Layout
    • Optionally-Loaded Modules
      • Optional Functions
        • Legacy Messaging Functions
        • Special-Purpose Functions
      • Optional SOW Key Generator
        • Chaining Key Generator
      • Optional Authentication/Entitlements Modules
        • RESTful Authentication and Entitlements
        • Multimethod Authentication Module
        • Simple Access Entitlements Module
      • Optional Authenticator Modules
        • Multimethod Authenticator
        • Command Execution Authenticator
    • AMPS Statistics
    • File Format Versions
  • AMPS Configuration Guide
    • AMPS Configuration Basics
      • Getting Started With AMPS Configuration
      • Units, Intervals, and Environment Variables
      • Working With Configuration Files
      • Including External Files
    • Instance Level Configuration
    • Admin Server and Statistics
    • Modules
    • Message Types
    • Transports
    • Logging
    • State of the World (SOW)
      • SOW/Topic
      • SOW/*Queue
      • SOW/ConflatedTopic
      • SOW/View
    • Replication
      • Replication Validation
    • Transaction Log
    • Authentication
    • Entitlement
    • Actions
      • Configuration for Actions
      • Choosing When an Action Runs
        • On a Schedule
        • On AMPS Startup or Shutdown
        • On a Linux Signal
        • On a REST Request
        • On Minidump Creation
        • On Client Connect or Disconnect
        • On Client Logon
        • On Client Offline Message Buffering
        • On Subscribe or Unsubscribe
        • On Incoming Replication Connections
        • On Outgoing Replication Connections
        • On Message Published to AMPS
        • On Message Delivered to Subscriber
        • On Message Affinity
        • On SOW Message Expiration
        • On SOW Message Delete
        • On OOF Message
        • On Message Condition Timeout
        • On Message State Change
        • On a Custom Event
      • Choosing What an Action Does
        • Rotate Error/Event Log
        • Compress Files
        • Truncate Statistics
        • Manage Transaction Log Journal Files
        • Remove Files
        • Delete SOW Messages
        • Compact SOW Topic
        • Query SOW Topic
        • Manage Security
        • Enable or Disable Transports
        • Publish Message
        • Manage Replication Acknowledgment
        • Extract Values from a Message
        • Translate Data Within an Action
        • Increment Counter
        • Raise a Custom Event
        • Execute System Command
        • Manage Queue Transfers
        • Create Minidump
        • Shut Down AMPS
        • Debug Action Configuration
      • Conditionally Stopping an Action
        • Based on File System Capacity
        • Based on an Expression
      • Examples of Action Configuration
        • Archive Journals Once a Week
        • Archive Journals On RESTful Command
        • Record Expired Queue Messages to a Dead Letter Topic
        • Copy Messages that Exceed a Timeout to a Different Topic
        • Deactivate and Reactivate Security on Signals
        • Reset Entitlements for a Disconnected Client
        • Extract Values from a Published Message
        • Shut Down AMPS When a Filesystem Is Full
        • Increment a Counter and Echo a Message
    • Protocols
  • AMPS Monitoring Guide
    • Statistics Types
    • Table Reference
    • Administrative Actions
    • Host Statistics
      • cpu
      • disks
      • memory
      • name
      • network
    • AMPS Instance Statistics
      • api
      • clients
      • config.xml
      • config_path
      • conflated_topics
      • cpu
      • cwd
      • description
      • environment
      • lifetimes
      • logging
      • memory
      • message_types
      • name
      • name_hash
      • pid
      • processors
      • queues
      • queries
      • replication
      • sow
      • statistics
      • subscriptions
      • timestamp
      • transaction_log
      • transports
      • tuning
      • uptime
      • user_id
      • version
      • views
  • AMPS Command Reference
    • Commands to AMPS
      • logon
      • Publishing
        • publish
        • delta_publish
      • Subscribing to and Querying Topics
        • subscribe
        • sow
        • sow_and_subscribe
        • unsubscribe
        • delta_subscribe
        • sow_and_delta_subscribe
      • Removing Messages (SOW/Topic or Message Queue)
      • heartbeat
      • flush
    • Responses from AMPS
      • sow: Content from Server
      • publish: Content from Server
      • oof: Content from Server
      • ack: Status from Server
      • group_begin / group_end : Result Set Delimiters
    • Protocol Reference
      • AMPS Protocol
      • Legacy Protocols Reference
    • Command Cookbook
      • Cookbook: Delta Publish
      • Cookbook: Delta Subscribe
      • Cookbook: Publish
      • Cookbook: SOW
      • Cookbook: SOW and Delta Subscribe
      • Cookbook: SOW and Subscribe
      • Cookbook: SOW Delete
      • Cookbook: Subscribe
  • Deployment Checklist
    • Ensure Sufficient Capacity
    • Apply System and AMPS Configuration
    • Create Maintenance Plan
    • Create Monitoring Strategy
    • Create Patch and Upgrade Plan
    • Create and Test Support Process
    • Conclusion
  • AMPS Clients
    • Performance Tips and Best Practices
    • C++
    • C#/.NET
    • Java
    • JavaScript
    • Python
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On this page
  • Basic Subscription
  • Subscription with Options
  • Subscription with Select List
  • Subscription with Content Filter
  • Conflated Subscription to a SOW Topic
  • Conflated Subscription to a Topic with No SOW
  • Bookmark Subscription
  • Rate Controlled Bookmark Subscription
  • Rate Controlled Bookmark Subscription with Maximum Gap
  • Bookmark Subscription with Completed Acknowledgment
  • Bookmark Subscription with Content Filter
  • Pausing a Bookmark Subscription
  • Resuming a Bookmark Subscription
  • Replacing the Filter on a Subscription
  • Subscribing to a Queue and Requesting a max_backlog
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  1. AMPS Command Reference
  2. Command Cookbook

Cookbook: Subscribe

This section presents common recipes for subscribing to a topic in AMPS using the Command or Message interfaces. This section provides information on how to configure the request to AMPS. You can adapt this information to your application and the specific interface you are using.

Command: subscribe

Basic Subscription

In its simplest form, a subscription needs only the topic to subscribe to.

Header
Comment

Topic (required)

Sets the topic to subscribe to. All messages from the topic will be delivered on this subscription. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Subscription with Options

In its simplest form, a subscription needs only the topic to subscribe to. To add options to the subscription, set the Options header on the Command.

Header
Comment

Topic (required)

Sets the topic to subscribe to. All messages from the topic will be delivered on this subscription. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Options

Subscription with Select List

In its simplest form, a subscription needs only the topic to subscribe to. To use a select list with the subscription, set the Options header on the Command to the select list specifier.

Header
Comment

Topic (required)

Sets the topic to subscribe to. All messages from the topic will be delivered on this subscription. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Options

Subscription with Content Filter

To provide a content filter on a subscription, set the Filter property on the command. The AMPS User Guide provides details on the filter syntax.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Filter

Sets the content filter to be applied to the subscription. Only messages that match the content filter will be provided to the subscription.

Conflated Subscription to a SOW Topic

To request conflation on a subscription, set the Options property on the command to specify the conflation interval. When the topic has a SOW (including a view or a conflated topic), there is no need to provide a conflation_key.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Options

A comma-separated list of options for the command. Set the conflation interval in the options. For example, to set a conflation interval of 250 milliseconds, provide the following option: conflation=250ms. To set the conflation interval to 1 minute, provide an option of: conflation=1m .

Conflated Subscription to a Topic with No SOW

To request conflation on a subscription, set the Options property on the command to specify the conflation interval. When the topic does not have a SOW, you must provide a conflation_key.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Options

A comma-separated list of options for the command. Set the conflation interval and the fields that determine a unique message in the options. For example, to set a conflation interval of 250 milliseconds for messages that have the same value for /id, provide the following option: conflation=250ms,conflation_key= [/id]. To set the conflation interval to 1 minute for messages that are the same, as determined by a combination of /customerId and /issueNumber, provide an option of: conflation=1m, conflation_key=[/customerId,/issueNumber].

Bookmark Subscription

To create a bookmark subscription, set the Bookmark property on the command. The value of this property can be either a specific bookmark, a timestamp, or one of the client-provided constants. The AMPS User Guide provides details on creating timestamps. Notice that the MOST_RECENT constant tells the AMPS client to find the appropriate message in the client bookmark store and begin the subscription at that point. In this case, the client sends that bookmark value to AMPS. The Bookmark option is only supported for topics that are recorded in an AMPS transaction log.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Bookmark

Sets the point in the transaction log at which the subscription will begin. The bookmark provided can be a specific AMPS bookmark, a timestamp, or one of the client-provided constants. AMPS also accepts a comma-delimited list of bookmarks. In this case, AMPS begins the subscription from whichever of the bookmarks is earliest in the transaction log.

Rate Controlled Bookmark Subscription

To create a bookmark subscription, set the Bookmark property on the command. The value of this property can be either a specific bookmark, a timestamp, or one of the client-provided constants. The AMPS User Guide provides details on creating timestamps. Notice that the MOST_RECENT constant tells the AMPS client to find the appropriate message in the client bookmark store and begin the subscription at that point. In this case, the client sends that bookmark value to AMPS. The Bookmark option is only supported for topics that are recorded in an AMPS transaction log.

To manage the message delivery rate to a bookmark subscription, set the rate option specifying the rate at which to replay messages.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Bookmark

Sets the point in the transaction log at which the subscription will begin. The bookmark provided can be a specific AMPS bookmark, a timestamp, or one of the client-provided constants. AMPS also accepts a comma-delimited list of bookmarks. In this case, AMPS begins the subscription from whichever of the bookmarks is earliest in the transaction log.

Options

A comma-separated list of options for the command. To control the rate at which AMPS delivers messages, the options for the command must include a rate specifier. For example, to specify a limit of 750 messages per second, include rate=750 in the options string.

Rate Controlled Bookmark Subscription with Maximum Gap

To create a bookmark subscription, set the Bookmark property on the command. The value of this property can be either a specific bookmark, a timestamp, or one of the client-provided constants. The AMPS User Guide provides details on creating timestamps. Notice that the MOST_RECENT constant tells the AMPS client to find the appropriate message in the client bookmark store and begin the subscription at that point. In this case, the client sends that bookmark value to AMPS. The Bookmark option is only supported for topics that are recorded in an AMPS transaction log.

The rate option specifies the rate at which to replay messages, while the rate_max_gap option specifies the maximum amount of time for AMPS to allow between messages.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Bookmark

Sets the point in the transaction log at which the subscription will begin. The bookmark provided can be a specific AMPS bookmark, a timestamp, or one of the client-provided constants. AMPS also accepts a comma-delimited list of bookmarks. In this case, AMPS begins the subscription from whichever of the bookmarks is earliest in the transaction log.

Options

A comma-separated list of options for the command. To control the rate at which AMPS delivers messages, the options for the command must include a rate specifier. For example, to specify that AMPS replays no faster than twice the original rate, include 2X in the options string. To specify that AMPS will go no more than 3 seconds without producing a message, regardless of the original replay timing, use a rate_max_gap of 3s. To provide the options described above, you would use the options string: rate=2X,rate_max_gap=3s.

Bookmark Subscription with Completed Acknowledgment

To create a bookmark subscription, set the Bookmark property on the command. The value of this property can be either a specific bookmark, a timestamp, or one of the client-provided constants. The AMPS User Guide provides details on creating timestamps. Notice that the MOST_RECENT constant tells the AMPS client to find the appropriate message in the client bookmark store and begin the subscription at that point. In this case, the client sends that bookmark value to AMPS. The Bookmark option is only supported for topics that are recorded in an AMPS transaction log.

To receive acknowledgment messages to a bookmark subscription, set the AckType on the command specifying the type of acknowledgments to receive. In this case, be sure to include the completed type.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Bookmark

Sets the point in the transaction log at which the subscription will begin. The bookmark provided can be a specific AMPS bookmark, a timestamp, or one of the client-provided constants. AMPS also accepts a comma-delimited list of bookmarks. In this case, AMPS begins the subscription from whichever of the bookmarks is earliest in the transaction log.

AckType

Sets the acknowledgment messages that AMPS returns. The AMPS clients typically request a processed acknowledgment for a subscription to verify whether the subscription succeeded. To receive a completed acknowledgment, which indicates the point at which replay is complete for the subscription, include completed in the set of acknowledgments requested. AMPS will return a message with a command type of ack and an ack type of completed at that point in the subscription.

Bookmark Subscription with Content Filter

To create a bookmark subscription, set the Bookmark property on the command. The property can be either a specific bookmark, a timestamp, or one of the client-provided constants. The AMPS User Guide provides details on creating timestamps. Notice that the MOST_RECENT constant tells the AMPS client to find the appropriate message in the client bookmark store and begin the subscription at that point. In this case, the client sends that bookmark value to AMPS.

To add a filter to a bookmark subscription, set the Filter property on the command. The AMPS User Guide provides details on the filter syntax.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Bookmark

Sets the point in the transaction log at which the subscription will begin. The bookmark provided can be a specific AMPS bookmark, a timestamp, or one of the client-provided constants. AMPS also accepts a comma-delimited list of bookmarks. In this case, AMPS begins the subscription from whichever of the bookmarks is earliest in the transaction log.

Filter

Sets the content filter to be applied to the subscription. Only messages that match the content filter will be provided to the subscription.

Pausing a Bookmark Subscription

To pause a bookmark subscription, you must provide the subscription ID and the pause option on a subscribe command.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

SubId (required)

A comma-delimited list of subscription IDs to pause.

Options (required)

A comma-delimited list of options for the command. To pause a subscription, the options must include pause.

Resuming a Bookmark Subscription

To resume a bookmark subscription, you must provide the subscription ID and the resume option on a subscribe command.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

SubId (required)

A comma-delimited list of subscription IDs to resume.

Options

A comma-delimited list of options for the command. To resume a subscription, the options must include resume.

Replacing the Filter on a Subscription

To replace the content filter on a subscription, provide the SubId of the subscription to be replaced, add the replace option, and set the Filter property on the command with the new filter. The AMPS User Guide provides details on the filter syntax.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

SubId (required)

The identifier for the subscription to update. The SubId is the CommandId for the original subscribe command.

Options

A comma-separated list of options. To replace the filter on a subscription, include replace in the list of options.

Filter

Sets the content filter to be applied to the subscription. Only messages that match the content filter will be provided to the subscription.

Subscribing to a Queue and Requesting a max_backlog

To subscribe to a queue and request a max_backlog greater than 1, use the Options field of the subscribe command to set the requested max_backlog.

Header
Comment

Topic (required)

Sets the topic to subscribe to. The topic specified can be the literal topic name, or a regular expression that matches multiple topics.

Options

A comma-separated list of options. To request a value for the max_backlog, pass the value in the options as follows: max_backlog= NN. For example, to request a max_backlog of 7, your application would pass the following option: max_backlog=7.

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A comma-delimited set of options for this command. See the section for a description of supported options.

A comma-delimited set of options for this command. See the section for a description of supported options. For example, to remove all fields except for /id and /ticker, you might use an option string of select=[-/,+/id,+/ticker].

subscribe
subscribe