Category: 6 how rules are used in streams

This chapter explains the concepts and architecture of the Streams apply process. An apply process is an optional Oracle background process that dequeues message s from a specific queue. These messages can be logical change records LCR s or user message s. An apply process either applies each message directly or passes it as a parameter to an apply handler.

An apply handler is a user-defined procedure used by an apply process for customized processing of messages. The LCRs dequeued by an apply process contain the results of data manipulation language DML changes or data definition language DDL changes that an apply process can apply to database objects in a destination database. An apply process applies changes based on rule s that you define. Each rule specifies the database objects and types of changes for which the rule evaluates to TRUE. You can place these rules in the positive rule set or negative rule set for the apply process.

If a rule evaluates to TRUE for a change, and the rule is in the positive rule set for an apply process, then the apply process applies the change.

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If a rule evaluates to TRUE for a change, and the rule is in the negative rule set for an apply process, then the apply process discards the change. If an apply process has both a positive and a negative rule set, then the negative rule set is always evaluated first. Subset rules are table rules that include a subset of the row changes to a particular table. A schema rule applies or discards either row changes resulting from DML changes or DDL changes to the database objects in a particular schema.

A global rule applies or discards either all row changes resulting from DML changes or all DDL changes in the queue associated with an apply process.

6 how rules are used in streams

For non-LCR message s, you can create rules to control apply process behavior for specific types of messages. An apply process is a flexible mechanism for processing the message s in a queue. You have options to consider when you configure one or more apply processes for your environment. The following sections discuss the types of messages that an apply process can apply and the ways in which it can apply them. Captured message: A message that was captured implicitly by a capture process.

A captured message contains a logical change record LCR. User-enqueued message: A message that was enqueued explicitly by an application, a user, or an apply process. A user-enqueued message can contain either an LCR or a user message. A single apply process cannot dequeue both captured and user-enqueued messages.

If a queue at a destination database contains both captured and user-enqueued messages, then the destination database must have at least two apply processes to process the messages. A single apply process can apply user-enqueued messages that originated at multiple databases. However, a single apply process can apply captured messages from only one source databasebecause processing these LCRs requires knowledge of the dependencies, meaningful transaction ordering, and transactional boundaries at the source database.

For a captured message, the source database is the database where the change encapsulated in the LCR was generated in the redo log. Captured messages from multiple databases can be sent to a single destination queue. However, if a single queue contains captured messages from multiple source databases, then there must be multiple apply processes retrieving these LCRs. Each of these apply processes should be configured to receive captured messages from exactly one source database using rule s.This chapter explains how rule s are used in Streams.

In Streams, each of the following mechanisms is called a Streams client because each one is a client of a rules enginewhen the mechanism is associated with one or more rule set s:. Each of these clients can be associated with at most two rule sets: a positive rule set and a negative rule set.

A single rule set can be used by multiple capture process es, propagation s, apply process es, and messaging client s within the same database.

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Also, a single rule set can be a positive rule set for one Streams client and a negative rule set for another Streams client. Figure illustrates how multiple clients of a rules engine can use one rule set.

A Streams client performs a task if a message satisfies its rule sets. In general, a message satisfies the rule sets for a Streams client if no rules in the negative rule set evaluate to TRUE for the message, and at least one rule in the positive rule set evaluates to TRUE for the message. Specify the changes that a capture process captures from the redo log or discards.

That is, if a change found in the redo log satisfies the rule sets for a capture process, then the capture process captures the change. If a change found in the redo log causes does not satisfy the rule sets for a capture process, then the capture process discards the change.

Specify the messages that a propagation propagates from one queue to another or discards. That is, if a message in a queue satisfies the rule sets for a propagation, then the propagation propagates the message.

If a message in a queue does not satisfy the rule sets for a propagation, then the propagation discards the message.

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Specify the messages that an apply process retrieves from a queue or discards. That is, if a message in a queue satisfies the rule sets for an apply process, then the message is dequeued and processed by the apply process. If a message in a queue does not satisfy the rule sets for an apply process, then the apply process discards the message. Specify the user-enqueued message s that a messaging client dequeues from a queue or discards. That is, if a user-enqueued message in a queue satisfies the rule sets for a messaging client, then the user or application that is using the messaging client dequeues the message.

If a user-enqueued message in a queue does not satisfy the rule sets for a messaging client, then the user or application that is using the messaging client discards the message. In the case of a propagation or an apply process, the messages evaluated against the rule sets can be captured message s or user-enqueued messages.

If there are conflicting rule s in the positive rule set associated with a client, then the client performs the task if either rule evaluates to TRUE. For example, if a rule in the positive rule set for a capture process contains one rule that instructs the capture process to capture the results of data manipulation language DML changes to the hr. Similarly, if there are conflicting rules in the negative rule set associated with a client, then the client discards a message if either rule evaluates to TRUE for the message.

For example, if a rule in the negative rule set for a capture process contains one rule that instructs the capture process to discard the results of DML changes to the hr. Streams client s perform the following tasks based on rule s:. A capture process captures changes in the redo log, converts the changes into logical change records LCRsand enqueues message s containing these LCRs into the capture process queue.

A propagation propagates either captured message s or user-enqueued message s, or both, from a source queue to a destination queue. An apply process dequeues either captured or user-enqueued messages from its queue and applies these messages directly or sends the messages to an apply handler.

6 how rules are used in streams

A messaging client dequeues user-enqueued messages from its queue. These Streams clients are all clients of the rules engine. A Streams client performs its task for a message when the message satisfies the rule set s used by the Streams client. A Streams client can have no rule set, only a positive rule setonly a negative rule setor both a positive and a negative rule set.In Streams, each of the following mechanisms is a client of a rules engine, when the mechanism is associated with a rule set:.

Each of these mechanisms can be associated with at most one rule set. However, a single rule set can be used by multiple capture processes, propagations, and apply processes within the same database.

In the case of a propagation or an apply process, the events evaluated against the rule sets can be captured events or user-enqueued events. If there are conflicting rules associated with a mechanism, then the mechanism performs the task if either rule evaluates to TRUE. For example, if a rule set associated with a capture process contains one rule that instructs the capture process to capture DML changes to the hr.

A system-created rule specifies one of the following levels of granularity for a task: table, schema, or global. This section describes each of these levels. You can specify more than one level for a particular task. For example, you can instruct a single apply process to perform table-level apply for specific tables in the oe schema and schema-level apply for the entire hr schema.

Capture the changes in the redo log for the specified table, convert them into logical change records LCRsand enqueue them. Capture the changes in the redo log for the database objects in the specified schema, convert them into LCRs, and enqueue them. Capture the changes to all of the database objects in the database, convert them into LCRs, and enqueue them.

6 how rules are used in streams

Propagate the LCRs relating to the specified table in the source queue to the destination queue. Propagate the LCRs related to the database objects in the specified schema in the source queue to the destination queue. All of the rule sets and rules created by these procedures use the SYS. When you create propagation rules for captured events, Oracle Corporation recommends that you specify a source database for the changes.

An apply process uses transaction control events to assemble captured events into committed transactions. To avoid unintended cycling of these events, propagation rules should contain a condition specifying the source database, and you accomplish this by specifying the source database when you create the propagation rules.

When you use a rule to specify a Streams task that is relevant only for an individual table, you are specifying a table-level rule. You can specify a table-level rule for DML changes, a table-level rule for DDL changes, or two rules for both types of changes for a specific table.

Here, every condition that begins with :dml is a variable. The value is determined by a call to the specified member function for the row LCR being evaluated.

So, :dml. For a capture process, these conditions indicate that the tag must be NULL in a redo record for the capture process to capture a change. Here, every condition that begins with :ddl is a variable. So, :ddl. This example instructs a Streams apply process to apply a subset of DML changes to the hr. These changes originated at the dbs1.

6 how rules are used in streams

Given these rules, the following list provides examples of changes applied by an apply process:.Twitch has exploded and has taken over a large chunk of online streaming. It's no longer just about video games, but also art and live performances There have been plenty of gamers that have hit the jackpot and made it big by creating content on Twitch, but it's not all fun and games - literally.

There are plenty of rules in place to protect both the streamers and the audience. Most of which are based on common sense, but the penalties have been criticized by some for being too harsh - Breaking any of the strict rules can and will result in a suspended or even terminated account.

They're not playing around. Let's take a look at 20 of the strictest rules Twitch streamers have to follow. It's one thing to stream content or activities meant to impersonate an individual or organization - it is prohibited, but you'll most likely get away with a short suspension.

But don't ever attempt to misrepresent yourself as a member of Twitch representatives! You might think it would be a funny way to prank someone, but Twitch has a zero-tolerance for this violation and it will result in an indefinite suspension. No one likes spoilers and Twitch is very strict on this. Some professional streamers do have access to game content and demos before the actual game is released and it can be tempting to raise viewership by streaming it.

This is a severe breach of Twitch's guidelines and can result in serious consequences. Any song or video that's playing in the background of a stream, especially a popular and paid-for stream, could potentially result in a copyright battle. If no recognition is given to the content used, this can quickly turn into legal issues as the streamer has not credited the sources that were used in the live stream.

The Twitch Services are technically not available to persons under the age of Anyone between the ages of 13 and 18 are only supposed to use Twitch under the supervision of a parent or legal guardian. However, there is no possible way of knowing how old the viewers are, so we suspect this rule is for Twitch to keep their hands clean just in case something were to happen. While Twitch does have some security measures in place to help protect user-uploaded content, they will not guarantee that any unauthorized copying, use, or distribution of this content by third parties will not take place.

Which of course means that all users have to agree that Twitch is not liable for any unauthorized use of your content. Pretty straight forward, really. Don't try to reverse engineer, modify, or in any way tamper with anything Twitch related.

Doing so will not be considered a prank and the punishment will be more severe than just a ban Viewers trust their favorite streamers enough to not call them out if they're "lurking. There's absolutely nothing wrong with this, but it can turn into a problem if streamers call out someone's username for doing it. Creators are role models and leaders of the communities they create or foster around them.In Streams, each of the following mechanisms is a client of a rules engine, when the mechanism is associated with one or more rule sets:.

Each of these clients can be associated with at most two rule sets: a positive rule set and a negative rule set. A single rule set can be used by multiple capture processes, propagations, apply processes, and messaging clients within the same database.

Also, a single rule set may be a positive rule set for one Streams client and a negative rule set for another Streams client.

A Streams client performs a task if an event satisfies its rule sets. In general, an event satisfies the rule sets for a Streams client if no rules in the negative rule set evaluate to TRUE for the event, and at least one rule in the positive rule set evaluates to TRUE for the event. In the case of a propagation or an apply process, the events evaluated against the rule sets can be captured events or user-enqueued events.

If there are conflicting rules in the positive rule set associated with a client, then the client performs the task if either rule evaluates to TRUE. For example, if a rule in the positive rule set for a capture process contains one rule that instructs the capture process to capture the results of data manipulation language DML changes to the hr. Similarly, if there are conflicting rules in the negative rule set associated with a client, then the client discards an event if either rule evaluates to TRUE for the event.

For example, if a rule in the negative rule set for a capture process contains one rule that instructs the capture process to discard the results of DML changes to the hr. These Streams clients are all clients of the rules engine. A Streams client performs its task for an event when the event satisfies the rule sets used by the Streams client. A Streams client may have no rule set, only a positive rule set, only a negative rule set, or both a positive and a negative rule set.

The following sections explain how rule evaluation works in each of these cases:. A Streams client with no rule set performs its task for all of the events it encounters. An empty rule set is not the same as no rule set at all. A Streams client with a positive rule set, but no negative rule set, performs its task for an event if any rule in the positive rule set evaluates to TRUE for the event. However, if all of the rules in a positive rule set evaluate to FALSE for the event, then the Streams client discards the event.

A Streams client with a negative rule set, but no positive rule set, discards an event if any rule in the negative rule set evaluates to TRUE for the event. However, if all of the rules in a negative rule set evaluate to FALSE for the event, then the Streams client performs its task for the event. If Streams client has both a positive and a negative rule set, then the negative rule set is evaluated first for an event.

If any rule in the negative rule set evaluates to TRUE for the event, then the event is discarded, and the event is never evaluated against the positive rule set.

However, if all of the rules in the negative rule set evaluate to FALSE for the event, then the event is evaluated against the positive rule set.Jump to main content or area navigation. Contact Us. There are over 3. Rivers supply our drinking water; irrigate our crops; power our cities with hydroelectricity; support fish and other aquatic species; and provide countless recreational and commercial opportunities.

Small streams such as headwater streams and their associated wetlands are equally important. These streams, including streams and wetlands that do not have water year round, play a key role in providing critical habitat, food and shelter for waterfowl, fish, and other aquatic species.

They also mitigate damage from floods, provide sources of drinking water, filter pollutants, and support economically important local and downstream recreational and commercial uses. Cities and town, farmlands, mines, factories, sewage treatment facilities, dams, and many human activities on the land have significant impacts on the quality of our waters.

Understanding the condition of rivers, streams, and wetlands is critical if we are to develop effective plans to maintain, manage, and restore them. National Aquatic Resource Surveys — Statistically-based surveys of the condition of the Nation's waters. Water Homepage.The world of Twitch is taking over the streaming world. From gaming and art to even live performances, Twitch is the go-to place for all your entertainment needs. But not just anyone can be a streamer, you need to follow all of these rules on this list if you want to make it out on top like some of the biggest names in gaming currently.

Hopefully, if you plan to start streaming your sick gameplay on Twitch, these rules will help you get a head start moving forward. Some individuals have tried to exploit Twitch by click-baiting and other nasty tricks to get more viewers, just take the high road and create an audience that sticks around no matter what.

By all means, dress how you want, but try to keep it simple and respectful for those watching. If anything this could end up making people unsub you and send you hate! Who wants that?

Resist the urge of self-promotion and stay humble! Instead of spamming the link to your Twitch and telling people to head over to your stream, reach out to other streamers on the same level as you and ask to collaborate. Grow your channel in a way that actually is unique and focuses on building a real audience that WANTS to support you. Would you want people to do that on your stream constantly? To the point the messages would just engulf the rest of the chat that actually wants to connect with you, no thanks.

If you want to catch the attention of a streamer, just be active in the chat like a normal person. Be respectful! Would you go up to someone in real life and yell at them in person? If you want to garner more attention on Twitch, just try interacting with the individual streaming, ask them questions you have and be engaging! Let them live their lives and watch the stream in peace! Many people in the streamer community that are viewers just want to watch a Livestream on Twitch in peace.

Kids are a huge audience to streamers so Twitch does prefer that you bite your tongue a bit if you can. Plus, it does tend to be a bit awkward when a streamer is constantly swearing nonstop, it always seems a bit too try-hard. Playing an intense battle in a game, we understand a few bad words might come out of your mouth.


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